Vintage CD player repair : Philips CD 371 AKA Radiola CD 1371 - Page 1
Forum section: electronics / repair

author: Vince
author_rank: Super Contributor
timestamp: April 13, 2021, 06:48:12 pm
content: Hello world,Among the 20 old cheap broken CD players I bought the other day.. is this little thing. I bought it for 10 Euros, a Radiola CD1371. Looked like a cheap random player to me, but bought it just because somehow I found it cute, and wanted to diversify my experience, and also it had an uncommon fault : seller said it was working/playing CD's fine, but the display was not displaying anything, never. So works, but going blind...Then when I popped the hood, was surprises to see a swing arm in it, a CDM 4/11, along with a TDA 1541A DAC !That's when Gyro told me that this little thing was actually nothing less than an old Philips CD 371, pure and simple, simply wearing a "Radiola" badge... because, I learned soon after, Radiola was actually a brand owned by Philips. So makes sense. This old Philips is worth a lot more than the 10 Euros I paid for it.. even found one on Ebay for 500 USD / 400 Euros, yikes !Could really do with some cash at the moment but... I am not going to sell it for a profit. I am now very fond of this thing, especially know I know it's a technically interesting player. So, am keeping it for sure !So... ater testing, here is what I found :1) Display does not work indeed, completely kaput. Gyro already told me it was a common problem on this player. The couple 7 segments LED displays, are driven by decoder which sports a serial interface to the CPU on the main board. Decoder goes south but the displays are fine. IIRC, Gyro said the faulty decoder chip can be replaced by an off the shelf decoder that's still available today ? Is that right ?2) Unlike what the seller said, the player won't read CD's. Seller is surprised, said it was working fine "last time" he tested it... now "last time" can be ages ago I guess... but regardless of how long that may be, I guess at least we can assume that if the pickup was good "last time".. it should still be good now, since it has seen no use/wear at all during that period of rest. The guy really was very decent, I will give him the benefit of the doubt, at least until proven otherwise, of course...So for now, we will consider that the problem could be due toA) The storage period causing trouble : electrolytic caps gone bad ?B) Physical damage during the transport.Here is what happens. Initial conditions : no CD present, tray closed, player at rest, and CD clamp/top part removed so I can see what the pickup is doing.Then I press the PLAY button and here is the sequence of events that that I witness, i chronological order1) Something strange from the get go : the tray motor runs for one second, in the direction where it wants to close the tray, which is already closed.....2) Laser turns on3) Spindle turns for one second or so, a CD revolution or so, while the focus servo goes up and down full range, once. Trying to focus then, I assume...4) Spindle stops for a split second5) Spindle turns again for one second or so, while the focus servo goes up and down full range, once... I guess performing a second attempt at focusing.6) This fails so spindle stop, and laser is turned off.Then if I press PLAY again, the whole sequence is carried out again.In the video below, I press PLAY a few times. A disc is present so you can't see the pickup, and the disc does not stop when spindle is de-energized, due to the inertia of the CD of course, but if you pay attention you can see the CD slow down a little bit then speed up again when the player does its second attempt at focusing.You can also hear that the CD is rubbing a bit.. don't know where it comes from.. the clamping arm I guess ? Not sure it would be enough to cause the player no to read the disc ? I mean the disc looks like it's turning quite effortlessly no ?...Still, would be cool if it didn't rub at all of course, but I don't know what I can do to fix that, in practice...Should I try to fix this before the fixing the display, or the other way around ?I have a Toshiba with a CDM 4/11 transport too, so I guess plug and play.. could swap transports to at least be 100% certain the problem comes from this, rather than some problem on the main board.So here we go... let's try to save this cute little Philips shall we....

author: Gyro
author_rank: Super Contributor
timestamp: April 13, 2021, 07:08:07 pm
content: Yay, the impatient little bugger gets his wish at last!I'd investigate the power rails first. The failure mode of the LED display is usually to lose the odd segment, not blank, which makes me suspect an issue with the +5V rail.The disc seems to be starting and stopping fine. You occasionally get a scraping sound from the disc clamp if the white nylon cage catches the edge of the clamp disc. Nothing serious, it just needs a little grease. If the clamp is badly worn then it can cause the transport to vibrate, but I don't see / hear that. It's a good idea to lubricate the hinge points and clamp with a little plastic grease.It might be worth a gentle clean of the lens too (at least this one has one!).P.S. The case looks in pristine condition, always a good sign (the PCB too).

author: Gyro
author_rank: Super Contributor
timestamp: April 13, 2021, 07:27:51 pm
content: Another thought. That Axial 47uF electrolytic (2546) located underneath the transport is notorious for failure, causing laser power stability issues. I would replace that immediately (as you have the transport out). A radial part is fine as long as you lay it flat.This could easily cause initial focus lock issues. Never attempt to change the laser adjustment without replacing this capacitor first.P.S. You can quickly replace the electrolytic without removing the PCB, just snip the existing leads at the body and tack on a radial one. Just don't apply heat for long enough to loosen the PCB solder joints.

author: shakalnokturn
author_rank: Super Contributor
timestamp: April 13, 2021, 07:51:33 pm
content: Yep Gyro knows his classics!To me it sounded like a slipping sound in your video, I'd check that the clamping is correct. I can't remember for sure but no doubt Gyro will chime in, I think there is a metal ball pivot between the white plastic and the black clamping disc.Maybe check that isn't lost or seized in old grease.Other than that usual checks... Swing arm swings freely, state of flex at the back plastic clamp on the lower right of the transport.

author: Gyro
author_rank: Super Contributor
timestamp: April 13, 2021, 08:00:15 pm
content: Haha, thanks shakalnokturn.Yes, there is a metal ball on the top of the black disc clamp shaft which bears on the underside of the main sprung flap. The white nylon bit is there to hold and centre the disc clamp when it is released and when it is dropping down onto the spindle hub and CD. If the two pivot points between the white nylon carrier and the main flap are a bit tight, it won't sit level and will slightly rub on the disc clamp. Everything just unclips.Earlier transports used a slightly rounded blunt plastic end instead of a metal ball. These tended to wear badly and cause the whole transport to shake.EDIT: Just reading back to the first post - Don't swap in the Toshiba transport at this stage, best to break one at a time.Another Edit (I miss a lot of questions):QuoteThe shift register/decoder is built into the display. It is easy to replace with a decode chip and standard common anode LED display though. The decoder is a (NS/Microchip MM5450 / ST M5450).

author: Vince
author_rank: Super Contributor
timestamp: April 13, 2021, 08:39:58 pm
content: Thanks guys for your input ! I knew I could count on Gyro's love of this little thing, and Shakal's total inability to go bed before 4AM !Gyro, it's too late : I have ALREADY swap transport with the Toshiba, see picture !At first, before doing that, I tried easing the pressure on the disc by removing the spring that holds the clap down. Not much difference...Once I had swapped the transport...the Philips worked just fine with the Toshiba guts....So... bad news. I was already so much in love with that beautiful piece of art that is this white cast resin CDM 11/4, and now it's dead, probablyWell I guess there is still a faint ray of hope for the white one.. maybe ?Shakal did say to make sure the swing arm was moving freely and.... actually I did compare the two transports and did notice a difference. The black one, which works, has a significant " springiness " to it, feels healthy, iif I shall say ? I mean if I pull it with my finger to its outer stop, fully outward, then release my finger all of a sudden... the pickup races to the inner stop and makes quite a loud "bang" as it impacts (sorry for brutalizing it, though). Also, if I hold the pick-up by hand to the inner stop, then release my finger.. the pickup will stay in place, but the white/defective one will bounce a little, move back 10mm or so, and stay there, strange. The white one is more sluggish, feels tired. Not as responsive or bouncy. I can feel the black one has good force to it, whereas the white one is very weak, like it was 100 years old. Nothing against 100 year olds, but the black one in comparison feels like it's 20 year old..I see no actual spring in the CDM, so t's just the magnetic magic that gives it its springiness, even when powered off ??So how does one proceed to "clean" a swing arm ? Don't want to mess with the thing and ruin it, out of ignorance....Can it be safely dismantled, then clean old grease if I see some, and add some new grease.. .which again I don't have so will have to do with machine oil for now, at least for debugging purposes. Worked fine on the Pioneer...Clamp : no metal ball anywhere. Both the Toshiba and Philips are constructed 100% the same way. Below pics of the Toshiba clamp as an illustration.There is just that white plastic thingy that keeps the spindle clamp in place while allowing to move, and also has some spring action to keep it centered.Both clamps look in the same condition / state, both move very freely. Both have remains of very dry and crusty grease, for sure, but still appears to move perfectly freely none the less.Condition of the Philips : yep, all the white plastic parts are like new, bright white, really like new. The Toshiba OTOH, all the parts are significantly yellowed. Maybe the owner was a smoker...I see that there is a small PCB under the swing arm, so there is some hope that the problem comes from there rather than the pick-up itself...But first, I need to give the swing arm its springiness back ! Tell me how I should proceed to do a good job of it, what tragic mistakes not to make if any.Making progress anyhoo !Here is a video where I compare the "health" of the two swing arms, one after the other. First the black one, that works, then the defective one.

author: Vince
author_rank: Super Contributor
timestamp: April 13, 2021, 08:45:37 pm
content: Quote from: Gyro on April 13, 2021, 08:00:15 pmThanks a lot for the details. So the displays do need to be replaced, was mistaken. But they zare nothing special as you said so should not be difficult to find an appropriate replacement... come to think of it, I do have a bunch of brand new green 7 segments LED displays in my drawers... 25 year old now, didn't think I would get to use them one day ! Will check dimensions and polarity...BTW, when you edit your past messages I don't get notified, so I miss the nice new content... spotted it purely out of luck, as I glanced over previous messages just out of... I don't know what, but I did....

author: Vince
author_rank: Super Contributor
timestamp: April 13, 2021, 08:49:17 pm
content: Forgot : did clean the lens on both transports, at the very beginning of the troubleshooting. Made zero difference. But, at least I know I can rule this out of the equation, which is always nice. The less variables there are, the happier I am.OK almost 11PM, going to bed. See you tomorrow evening for more swing arm action...

author: Gyro
author_rank: Super Contributor
timestamp: April 13, 2021, 08:59:38 pm
content: The white CDM isn't necessarily dead, certainly give it the benefit of the doubt. The swing arm does look a tiny bit stiff, not too bad though. The springiness actually comes from the flexi-print ribbon, there is no physical spring. The white movement is closer to what I am familiar with actually.No don't dismantle the swing arm suspension. If you release the clamping leaf springs (with the ball in the middle, it will affect the vertical angle of the swing arm (it will be at different height at each end of the swing. The service manual does have the alignment procedure, but is involves 'eyeballing' it with a transparent disc and a linear light source (like a florescent tube). I've never done it, and never quite understood it from the picture.It is normally sufficient to lubricate the ball to swing-arm pivot points with a tiny drop of silicone oil as Philips recommend. A small amount on the the tip of a darning needle for access.As I mentioned before, it might just be a dirty lens, or the laser drive is marginal due to that electrolytic capacitor.Most CDM4s are black by the way, the earlier ones were just using up stock of the CDM2/10 white mouldings I think.

author: Gyro
author_rank: Super Contributor
timestamp: April 13, 2021, 09:01:10 pm
content: Quote from: Vince on April 13, 2021, 08:49:17 pmHaha, good progress for one evening. Good night.

author: Gyro
author_rank: Super Contributor
timestamp: April 13, 2021, 09:13:30 pm
content: Quote from: Vince on April 13, 2021, 08:39:58 pmThe metal ball is on the top end of the spindle clamp shaft (you're showing the bottom). Yes, the three springy arms are to centre the clamp so that it goes down smoothly onto the hub and disc. Dry crusty grease is normal at that age, it's enough to just make things a little sticky. You can gently pop the white carrier out of the main flap. You'll then see the ball and be able to clean up better.

author: Vince
author_rank: Super Contributor
timestamp: April 13, 2021, 09:31:25 pm
content: Not in bed just yet ! Within 5 minutes though !Wanted to add a quick little something / erratum before I call it a day : I realized I fucked up my springiness test ! The black one, plugged into the Philips player.. was actually powered UP !!If I remove power, it behaves just like the white one, but still feels much stronger/healthier...So the springiness is not magic after all , just the flat flex ?!Feeling stupid.........................Lens : I just wrote above that I cleaned them both long ago, with no improvement at all, don't you read ?!Laser blue cap.. hmm yes good point, might be good enough to get a healthy laser going, but maybe not good enough to get a weaker laser going... will definitely look into that indeed, I promise ! I don't have a new cap to replace it with though.. only 30 year old salvage caps, which are likely just as bad or worse... no ESR meter at hand to actually check for the condition of the cap. Yes, I am looking into getting a tester in the short term, I am fed up not being able to know what I am doing with old caps, I am sick of it. Will try one of my old caps anyway. Won't be new but it will probably be a different state of bad, so might manifest as a slight difference in overall behaviour of the drive, which would therefore confirm the problem and motivate me to spend 2 hours riving to town center and back, to go get a new cap at my local electronics shop...Or maybe if the value of the cap is not that high, I could cobble an equivalent cap with a bunch of FILM caps.. there tend to still be good even after decades, they don't degrade, so old film caps might still be plenty good enough to get the laser going. I don't know.. trying to do my best to make progress !Maybe I could plug the white one into the Toshiba player, hence with a cap in a different state of bad, might spot a difference in behaviour this way.Cleaning swing arm : thanks fr the big warning and glad I asked !!!OK, won't take ANYTHING apart.. .just doing my best to clean and lubricate it IN SITU !Clamp : OK my bad, will take that stuff apart to try and see that bloody metal ball....REALLY going to bed now, see ya !

author: Gyro
author_rank: Super Contributor
timestamp: April 13, 2021, 10:03:09 pm
content: Just to get a head start on you for tomorrow!!!Quote from: Vince on April 13, 2021, 09:31:25 pmHa, yes, that would explain it!QuoteThere isn't anything particularly special about that cap, it's not low ESR or anything. It's just that that particular range of axial Philips ones have a reputation for drying out and losing capacitance. A salvage one will probably be ok for testing. If your DMM has a capacitance range, a value check would be good enough.QuoteI would be tempted not to swap the transports too much at this stage. Firstly there is the risk of ESD damage, and secondly, the possibility that there might be a significant difference in laser current setting.

author: Gyro
author_rank: Super Contributor
timestamp: April 14, 2021, 09:34:56 am
content: If you have the CD371 basically working (producing audio?) using the CDM4 from the Toshiba, it's probably a good time to turn your attention to the display problem.Note: For future search purposes the Toshiba model is XR-9128 - It took me ages to track it down in your previous repair threads last night.The main board microcontroller is clearly receiving +5V and working as you have CD operation and key scan, so the problem is limited to a front panel or interconnects. Time to remove the front panel PCB and check for +5V. I think there's a fusible resistor on the +5V rail (the CD371 has fusible resistors on the individual supplies of every IC!). If no supply is present, then it could be a dry joint or ribbon cable problem. If it is present at the display, then it's either a completely dead display or problem with the 3-wire serial interface (data, clock and data enable) again, dry joint or ribbon cable. It's easy to continuity check back to the microcontroller pins.As I mentioned before, the display data interface is very simple, the display decoder is a 35 bit shift register. You basically set the first bit high, followed by 34 bits of display segment states. Once the 35th bit reaches the end of the shift register, it latches the following 34 bits and outputs to the relevant pins. There is no multiplexing, it's a straight one to one match with the common anode display segments. The MM5450 datasheet gives better detail.This page gives full details of the correspondence between the data bit, and display segment (or LED), together with an example of replacing a broken display with separate MM5450, ordinary displays and some stripboard...http://audio.etata.hu/2010/12/17/nsm4202/I've also attached a copy of the pin mapping table for reference (just in case the page ever goes away). Note that I have edited this - the original shows Bit 34 as not used. From looking at the CD472 front panel circuit, I think Bit 34 is the IR remote indicator of IR equipped players (CD372 / CD472). Note that the CD371 front panel PCB also has an unpopulated footprint for an IR receiver.

author: Vince
author_rank: Super Contributor
timestamp: April 14, 2021, 10:01:26 pm
content: OK it's late and I am super tired so I will have to keep it short...Spent a few hours on the thing. Did as Gyro suggested , didn't even touch the CDM, spent all my time on the display/front panel board.Took it out of the front panel, power up.. and go figure, by some miracle it DID display some stuff !!!So it's not dead...To cut a long story short, I fiddled with the thing for hours, tried everything a brain can think of. Tried all the easy stuff, nothing worked.No bad connection no bad solder joint, no broken traces.. only found a couple 22k resistors that went open circuit, but there role is not vital, they are in parallel with the two decoupling caps (yes blue Philips..) , bleeder resistors to make sure the display goes off instantly when the user powers the unit off, I presume ?The blue Philips I pulled one leg off, to test them reliably. Indeed you wee right Gyro, these bloody caps do lose a lot of capacitance of time ! In this case almost 50% !!! Supposed to be 47uF, bot measured about 26uF... still, power suply looks good on the scope, no excessive ripple or voltage drops, nothing that I would worry about.Then scope the serial interface, pics attached.What I found interesting is that the CPU refreshed/overwrites the display constantly, whether or not there is an LED that needs its status changed. IT just spits out the same data frame over and over again, go figure.Scopes the Chip Enable pin (active low it appears). It refreshes the display at about 30Hz. Active for about 4ms out of a period of 32+ ms or so.The clock signal is gated by the MCU accordingly, so it spits out 4ms bursts of pulses. Clock runs at 14kHz. A pulse lasts about 70us, so... yes, I counted the pulses one by one, there are 56 of them ! 56... for a 35 bit register ?! How can that work ? What am I missing ? What's the point ? The MCU is well aware that the register is only 35 bits long, so why bother shift it 56 times ?! Eh ?Then the data frame. Perfectly stable and consistent, nothing wrong there. if I press the repeat or pause button, which have their dedicated discrete LED, I can see a bit in the frame go on and off. If I switch to "time" mode, then I can see the last bits of the frame change every second, in a counter like pattern, as expected.So the CPU is definitely sending proper data, no worries. It's the display module that's bad. More precisely, I would say the decoder (chip on board, big black blob behind the LED digits) is fine, since I managed, for 30 seconds to have it behave perfectly and I had alllll the LEDs and digits working perfectly. Didn't last long though. Most of the time it displays partial garbage and partial sense. often it won't display anything at all. It's completely random.Point is. I know the module is getting good data, all the time... 30 times a second. I also know the LED displays are good. I also know the decoder itself and shift register are good, since it worked once, and works partially most of the time. So... can only be a bad bond between the LED digits and the chip output pins. When the display is all dark and "frozen", unresponsive... it comes back to life when I press hard with my finger on the LED displays.So, bad luck... I can fix the bad joints of course, no access. So will need to do like the guy you linked the website of, and replace the chip. Looking at his pictures (he doesn't mention this particular point in the text), it looks like he managed to reused the existing LED display.For the rest of his project, it looks so messy and horrible, there is no way, no way in hell that I am inflicting this to my lovely player, or to my eyes really, as it hurts so much. At least it works, I get that... but still.So I think it should be possible to make replacement module using a surface mount chip...stuck behing the display, just like the original chip on board.. except replacing chip on board by a surface mount chip. Sadly the MM5450 according to the datasheet I pulled, is not available in surface mount packages. There is a PLCC package which could be surface mounted, but I guess it would be too thick to fit, couldn't clear the front panel board I fear.So will have to search see if I can fiund a comparable chip in a surface mount package.Goal is to make a replica of the existing module, ie NO ugly wiring... zero wiring. Just the LED displays soldered to the custom PCB, and the decoder chip soldered directly to the PCB, with traces linking the two. zero ugly wire. If I can't find a suitable chip, I don't see why we couldn't just daisy chain a few bog standard 8 bits shift registers ?! The advantage of the M5450 though, being it allow to control the intensity/current of the display with a single pin...Anyway, this sounds like good fun, but it's time consuming and I have not made a PCB in 15 years... times travels faster than light eh....So it will have to wait... house work is the priority.So now that the display problem has been diagnosed.. tomorrow I will get back to the CDM.. see if I can get it working...Midnight, exhausted, good night and see you tomorrow for the next and probably last (for now) episode....

author: shakalnokturn
author_rank: Super Contributor
timestamp: April 14, 2021, 10:42:09 pm
content: https://www.diyaudio.com/forums/digital-source/259790-nsm4202a-led-display-module-replacement-philips-sony-cdm-transports.htmlBuilt modules can be found for 35€, maybe less, on Aliexpress.Regarding the 56/35 bit enigma, possible that the CPU is ready for 6 digit displays (time + track N°) just the excess data is dismissed on the 4 digit models. Besides isn't the MM5450 a workaround with hardware similar but not identical to the original design?Maybe you could get away with a couple of these:https://www.st.com/resource/en/datasheet/stp16dpps05.pdfOrhttps://www.njr.com/electronic_device/PDF/NJU3716A_E.pdfOr four 74 family 8 bit SIPO shift registers...I'd probably go for a PIC, some code and a multiplexed LED drive to simplify the PCB layout...

author: Gyro
author_rank: Super Contributor
timestamp: April 15, 2021, 10:11:52 am
content: Sorry to hear that it is the display module, I feared that it might be but (because it was totally blank) I hoped not. Responding to physical pressure is a sure sign of a bond wire failure on the blob-top IC, which i think was the general issue with them.Yes, looking again at the page I linked, the guy did re-use the existing display LEDs by tacking onto the rear of the display module. Personally I would have used finer wires, which might have made it neater! Yes the smallest package for the MM5450 is PLCC.I found another site where the author has really gone to town on designing pin compatible replacement display modules...https://www.bramjacobse.nl/wordpress/?p=171I notice that some of the ebay replacements (I didn't look at Aliexpress) are populated PCBs which re-use the plastic moulding from your original display - still cost more than you paid for the player though. I think these designs are lifted from the above site.@shakalnokturn: I suspect that NS did use the same die for both the display and the IC, they originated both, and the display does bring out the relevant external LED drives on pins. No way to be sure of course. I can't find the display datasheet anywhere on the web (I will try my old NS databook collection) but one of the block diagrams on the above mentioned site looks identical.By the way, the CD471/CD472 use the MM5848 which has the same functionality, but with high voltage outputs to drive their VFD displays, making them interchangeable on the same main board (only the transformer is different, having extra windings).Very interesting findings on the serial data stream. I had never thought to actually scope it, but was expecting it to only update the track data on track change (obviously it would need to be more often on time display). The extra data bits are curious. As shakalnokturn suggests, it may be for extra digits - although the player defaults to track number display and this includes Index so is already 4 digits long. It does explain why the display enable signal (which just internally gates to clock inside the IC), otherwise the 35th bit latch scheme would only need data and clock to operate (the CD47x front panels use a diode-OR scheme to gate the clock as there is no data enable pin).One of the reasons that I like these players is that they offer opportunities to be used in a home project. The CD tray and loader mechanism are separate from the case moulding - if you look at later models (the CD610 for instance), things like the loading motor mount are part of a molded 'web' which is part of the case moulding (the PCB smd parts are accessed from below, but it is a pain to get at top side parts).The separate mechanics makes it very easy to integrate the whole assembly into your own constructed case, with brushed Aluminium, Wood etc. (take your pick!) front panel. There is plenty of front overhang on the tray so all that is needed is a slot in the front panel. The front of the tray is even removable (Rotel substituted a metal one). The tray mechanism is also the simplest design of all the players, no cams or transport movement, just one belt and gear wheel. You could then implement just the front panel controls that you wish - for instance, a minimalist 2 digit display to just display track number, minimal controls for eject, play, pause, stop, and maybe track selection (although you could just make these functions available on the IR remote).Such a case would make it easier for quality modifications, move the DAC to a separate PCB with separate analogue supplies and bigger DEM circuit decoupling capacitors. You will find that the higher-end, much more expensive versions of the player (from Philips, Marantz, Arcam, and others) made such changes, but the actual circuit changes are minimal, mostly additional supply regulators and minor component quality changes. S/PDIF is also available as a output on the SAA7220 (parts just not populated on the PCB), making it suitable as a Transport.The reason that so many manufacturers' models were based on the CD373layout is that it uses I2C interface. This made it much easier for them to customise lots of differentiating features and variations - very handyifyou have your own front panel tooling facilities, custom multiplexed VFD sourcing capabilities etc. but much harder from the DIY perspective. This PCB also has a very strange placement of the TDA1541A DAC - right at the front of the PCB, well away from the analogue opamp I/V converter and filters. It's not ideal to have long, noise susceptible analogue tracks when the DAC has a settling time of 1uS and feedback is involved! The CD371 layout is much more logical (and accessible).This is all stuff that I have every intention of doing - I just haven't got around to it yet!Sorry, that was a bit of a wall of text.

author: Gyro
author_rank: Super Contributor
timestamp: April 15, 2021, 10:54:45 am
content: Just to round off, I though I would document the changes that I have made to my CD472 as they currently stand. These have had a major impact on sound quality (as I said, the differentiation between higher end and lower end models (as long as they used the same transport and DAC was very small in component changes).Firstly, circuit and ground noise is a big factor. The SAA7220 is a power hungry and noisy device for instance. The board layout does benefit from the entire top side being ground plane but it has quite a lot of slots due to components.1. Clock. I replaced the simple crystal on the SAA7220 with a canned oscillator. Clock stability is key, and the on-chip oscillator isn't good due to it being a noisy IC. Clock improvements were made by Arcam and others.2.Replacement of IC electrolytic decoupling capacitors on the main power rails, DAC and opamp local supplies. The ones on the CD371 are the minimum that Philips could easily use. In particular, I used a large OSCON on the SAA7220 sypply for minimum ESR.3. Replacement of the DAC DEM smd ceramic filter capacitors with PPS smd ones. Filter capacitor values have an effect on sound quality. Phillips and Marantz went from 100nF ceramic to 220nF film capacitors on their high-end models. Arcam used 220nF with 470nF for the two most significant bits.4. Replacement of the opamps. Basic- mid range players use LM833, higher end use NE5532. Both are pretty old designs now. I inserted socketed OPA2134s, not optimal, but they were what I had at the time. There are some ADI opamps which are faster and probably a better speed match for the I/V conversion stage. I Removed the headphone opamp - it was fixed level anyway.5. Removal of the output muting transistors and replacement with a muting relay. While the muting transistors shouldn't affect anything on paper, they do have an effect. Higher end players used muting relays (N/C contacts to ground the outputs).6. Bypassing the output coupling bipolar electrolytic capacitors. Possibly age is a factor, but bypassing does improve things. BTW, it is helpful to use 'Vero' style push fit PCB pins (intended for stripboard) inserted from the underside of PCB for access to signals. This minimises the risk of track damage and minimises the number of times that the board needs to be removed.EDIT:7. I forgot, replaced the In4002 rectifier diodes with fast, soft recovery types - another noise source.8. Arcam inserted 390R series resistors in the I2C signal between the SAA7220 and TDA1541A, this reduces noise injection into the TDA1541A die (I have seen other implementations where attenuators are used to reduce the signal swing to TTL levels). I haven't tried this yet.I've attached some photos. Sorry, I had the flash on. The mods are rather messy, but functional.

author: shakalnokturn
author_rank: Super Contributor
timestamp: April 15, 2021, 11:01:28 am
content: Walls of text don't scare Vince!

author: Gyro
author_rank: Super Contributor
timestamp: April 15, 2021, 11:20:11 am
content: He is rather good at them!

author: Gyro
author_rank: Super Contributor
timestamp: April 15, 2021, 11:37:05 am
content: Just to show how overboard I have gone previously with the TDA1541A - this one is standalone, with slave clocking of the CD player (as transport) and data re-syncronisation. The result is very detailed, but lacks the bass quality of the CD472.Please bear this aberration in mind when listening my advice!

author: shakalnokturn
author_rank: Super Contributor
timestamp: April 15, 2021, 12:02:52 pm
content: SRPP output stage? I had that as a project for some (or no) day.

author: Gyro
author_rank: Super Contributor
timestamp: April 15, 2021, 12:17:49 pm
content: No, they're standard cathode (LED) biased triode gain stages using former Soviet 6S45Ps. Plenty of gain for passive resistively loaded TDA1541A outputs (20R) and nice low output impedance.Taking the photo jogged me into waking it up again. On listening again, it is pretty magical, (even the bass).It makes me realise that I still have some work to do on the analogue supplies on the CD472!

author: Vince
author_rank: Super Contributor
timestamp: April 15, 2021, 06:08:13 pm
content: Wowwwwwww..... little did I know what I would find on here once back home !So much info in there... no way I can reply to everything so... just a big thanks for all the links info and pictures, a gold mine.Looks like my 10 Euros CD player is now the star of the show, and will be turning into a long term mod project.... that will end up costing me 300 Euros at the end. Definitely can't afford that at the moment, nor the time to do all that. But, this thread will now be my bible and I can read your messages later on when I have time and money to tinker with this player.You both went very wild, deep into mods ! I like to make fun of audiophools, and I would hate to become one... but you are both electronic guys, rational and tehcnical people, so I trust you to draw the line between what is actual facts, science.. .and just plain paranoia or "religious" audio faith....So might mod my player here and there at some point, just to see if I can actually hear a difference. You do, so maybe my brain will too...However, my brain is not trained to appreciate quality sounds. Am 43 and all I have had for now are a pair of shitty Altec Lansing small amplied speakers connected to the on-board sound chip of my 15 year old desktop computer motherboard.....Only 4 months ago did my dad give me these shitty Toshiba speakers to go with the Philips CDC486 I fixed for him, now mine. And the amp that goes with it, cheap low end Sony amp, that I bought defective for 10 Euros. So I guess it must output crap, but I wouldn't even know, not having heard any other amp / speakers...I guess brain needs to make side by side comparisons to train itself and spot the good from the bad...Might happen sooner than I expected : last week, an old grand-pa on his electric bicycle, as he went past my house, noticed my lab and collection of old vacuum Tek scopes through the window. Parked his bikes, and sticked his head onto the window, trying to get a better view. I didn't know if I should call the police, or grab a hammer to get him out of the way.... I opted for the friendly approach. Glad I did. Guy is an old electronic guy, studied electronics in the early '80s. He was a bit into audio stuff himself. He scrapped a shit load of old electronics stuff just the other day, wished we had met a few weeks earlier so he could donate all that to me ! What a waste, a tragedy. But, he still have a little bit of stuff left. He showed me pics, will bring the stuff with his car this week-end. He will donate to me 3 pairs of loudspeakers. Some crappy/ obscure ones branded "Boston" he said, but also decent 3 way stuff a pair of Technics, and a pair of Marantz, in nice wooden cabinets. It's bound to be much better than my crappy small 2 way low end Toshiba speakers so... maybe I will a difference with his speakers. He did say however that speakers don't age well so they might degraded and not perform well ?! Well, it's all free so who cares. Will plug them in and see what happens !Also some modern junk, jsut so I can salvage the electronic board from them and ditch the rest : a big 5.1 "home theater" 2x100 Watts IIRC, and also a couple DVD players, and also a small old Sony CRT monitor, like old CRT TV/monitors, always a bunch of cool power resistors and high voltages caps to salvage. Love CRTs....Guy came back to my house a minute ago, and gave a little something already, see pics : an antic " QUAD " pre-amp, model 33.I gather QUAD was high-end audio, like NAD ROTEL etc ?Look at that thing, with DIN input connectors at the back not RCA's ?! Took a pic of the inside just because I love you so muchHuuuuuu... just checked the interweb... this antic QUAD 33 preamp is actually known to the world ? Found one for sale on Ebay for.... 1200+ Euros ?!https://www.ebay.fr/itm/Vintage-Quad-33-Controle-Pre-ampli-Tres-Bon-Etat-Entierement-Revise/373522379328.. because it's in good nick and serviced. "as is" units still sell apparently for 275/350 Euros, still a fortune !I will happily "service" it and give a good clean, for the extra 1,000 Euros !But mine is missing a button at the front, so the audio people will probably deem that my unit is therefore worth nothing anymore, or maybe 10 Euros for parts !For 1250 Euros though, worth the trouble of 3D printing one and going to te trouble of trying to give it some patina to make it look legit !Anyway, back to the little Philips.As for the display, l now understand it was a third-party off the shelf unit used in a gazillion old players, and that they all go bad 30 35 years later. Hence why apparently so many people are trying hard to find a work around, and the "market" is so large that some sell ready made units on the interweb.So, in retrospect... it was given that my module would be bad !I still think I would go through the trouble of designing my own module though, though that will be sped up by all the work that these people have already done. Mainly, it looks like the first guy, who managed to salvage and reuse the original LED display, had horrific DIY electronic skills. On the othe hand, the guys who designed their own PCB, and surface mounted the 5450 PLCC like I was thinking I could do.. did not reuse the existing display. There replacements don't please me. Segments don't have the same shape, and color matching with the surround discrete LED's could be a nightmare.So, what I retain from all the info/links you gave me on that subject is :1) Yes it's possible to make a replacement module, so no need for a extra board with tons of ugly wires. It can be made to look as clean tidy and compact as the original.2) it IS possible to reuse the original display, since that guy managed to do it...3) Surface mounting a PLCC 5450 can indeed do it, it fits, just.So if I ever get the motivation to make my own module, then I would target a surface mounted PLCC 5450 + reusing the original display.If I can't, well might as well buy a ready made module, but it sucks.. that would be a defeat...But at least it would get the player working again, would be a clean technical solution, quick solution, and not cost a mega fortune, and not cost me any R&D time. So whatever I end up doing, at least I can sleep on both ears : this particular problem has already been tackled and solutioned, great....So now I am left with the CDM not working. Let's see if some cleaning and a replacement laser capacitor will improve things.... stay tuned !No Gyro, as you have gathered by now, I am not at all afraid of text walls. I am rather afraid of people who are incapable of erecting one !How the hell could you and Shakal have conveyed all the useful information you gave me.... in a one liner tweeter style ? Information needs SPACE !!!Bandwidth these days is CHEAP ! There is no good reason to restrain your thoughts...99,9% of the internet bandwidth is porn, spam and useless crap on youtube and social media... let's use the remaining 0.1% to write useful stuff !!!

author: Gyro
author_rank: Super Contributor
timestamp: April 15, 2021, 08:30:04 pm
content: I though it might be a nice little surprise for you.Your CD371 has the makings of a nice little project. It has all the same relevant parts as some of the really-expensive-on-ebay high end players (ok a few of them use the selected S1 grade part, but not all, and there isn't much difference.I still think you could make up a replacement display using an MM5450, and a bit of stripboard - as an interim step to your final metal cased monster! Enough to be useable anyway, and you only really need to connect up two digits (only 15 wires)... or none at all if you just want music out of it!Yes, there is a fine line to be drawn on this forum between good solid engineering and Audiophool accusations. I stick with the former, but I am sometimes surprised by what my ears tell me and the sound suddenly becomes 'right' or 'special', it makes the effort worthwhile. A good differentiator in approach is not buying ridiculously expensive components!As I mentioned before, it is surprising how much grading in sound quality and product positioning that the likes of Philips, Marantz etc. could achieve with really very minor component changes, it's really a happy accident that they put such a nice transport into the relatively cheap 371/471 series. The TDA1541A is so good that they must have actually had to 'engineer down' the sound quality on cheaper units! It all changed later with the lower quality and cost TDA1543 and then sigma delta (Bitstream in Philips language) DACs that they designed for lower production cost and better yield - sound quality was a secondary consideration. If you compare the THD+N and dynamic range specs with the earlier DAC, it is clear. Cost was the main driver. Likewise with Burr-Brown and their transition from Multi-bit to sigma delta.Look at some of the high cost Philips based players on ebay and download their service manuals - you will be surprised.It sounds as if you have come into contact with a nice... and generous, person. Yes, Quad is a long established (probably around 70-80 years old by now) quality British HiFi manufacturer, one of the best and far higher than Rotel and NAD (NAD were the 'good value for money, affordable' new kids back in the '80s) - if your new friend mentions electrostatic speakers, or Quad II valve amps, be very humble! Yes the Quad 33 preamp can go for serious money, particularly if accompanied by the matching 303 power amp. Enough to finance personal project costs, or to enjoy. Yes 'service' in this context means replace the electrolytics and clean the contacts, leaving as much original as possible.I'm glad the information from both of us has been helpful [EDIT: and you contributed some useful data too!]. It's been quite therapeutic to actually write it down and re-discover some of it - I purchased an MM5450 today in preparation for the master plan implementation!

author: shakalnokturn
author_rank: Super Contributor
timestamp: April 15, 2021, 08:35:56 pm
content: Nice gift that Quad... I see there's a fistfull of blue Philips and plastic ERO? electrolytics in there. Another topic on the way.Depending on the size of the Sony monitor I'd hold on to it. Some HP TE used Trinitron CRT's that are usually way overtime.

author: Vince
author_rank: Super Contributor
timestamp: April 15, 2021, 08:36:17 pm
content: OH !Just realized, at the back of that QUAD preamp unit, it reads "Made in Huntingdon, England " ?!Wow, now that brings some memories !!!Used to live there !Moved to the UK for 3 years to do my BEng degree in electronics, between 1998 and 2001.Uni was located in Hatfield, Herts, north London, but for my "Sandwich" / placement year, I found a position in a small company in Cambridgeshire, in a little village by the name of Saint-Ives, which is right next to Huntingdon ! My boss at the electronics R&D dept. lived in Huntingdon.. little did I know that QUAD was located there as well !Might have paid a visit had I known.Company was called Webtec, still in business today. Actually I still have the business card of my R&D boss in my Wallet, 20+ years later ! LOLhttps://en.webtec.com/Even found a couple pictures of the prototype I was developing... feels like yesterday but was 21 years ago ?! Time fliesRuns on this back then fancy PIC thing, a state of the artFLASH micro-controller with in circuit programming, and built-in EEPROM ! WOW !!! Sounded like a revolution compared to the Intel 8051 I cut my teeth on at school just a couple years earlier !I remember it was a PIC 16F876 or 877 can't remember. It was so atrocious to program that I missed the old 8051 so much.At the very beginning of my placement, before I was given this then state of the art PIC, I dabbled briefly with a 17CXX IIRC, an antic PIC with a glass window to erase its internal EPROM ! Would spend most of my day waiting for the small UV eraser on my desk to clear the bloody thing so I could change a line of code and give it a try ! What a pain that was !

author: Vince
author_rank: Super Contributor
timestamp: April 15, 2021, 09:13:28 pm
content: Quote from: shakalnokturn on April 15, 2021, 08:35:56 pmOnly one blue Philips that I can see. As for the ERO ones.... you have not yet taught me about them... which ones are they ?The small radial ones, in a perfectly cylindrical plastic body, either black or orange ? Lot of them indeed. Just noticed one of them let the magic smoke escape !!! A black one, located from what I guess must be the power supply board. Right next to the big blue Philips.QuoteOh no, I had only a brief look at it on his smartphone, he took a crappy pic. From that brief look, it looked to me like a tiny minuscule portable monitor... like a portable TV or something, but I am sure he said it was a "monitor"... looked light brown, either that or extremely yellowed beige... looked anti, crusty, an extreme piece of junk no-one on earth would want near him. But he said he would bring me all the stuff this week-end, so I will be able to know for sure, and report back of course !

author: Vince
author_rank: Super Contributor
timestamp: April 15, 2021, 09:39:58 pm
content: Quote from: Gyro on April 15, 2021, 08:30:04 pmYeah you and Shakal had me grow very fond of this little bugger, I love it now, want to fix it and mod it and enjoy it.. not going to sell it, no no no...QuoteHmmmm....... either I am weak person and/or you have a lot convincing power but.... OK let's do something real quick... thinking of it, it really doesn't look that complicated/long to do. Will order one or two of these chips and some prototyping board... but just a few wires, not ugly mess... just a proof of concept thing, to motivate me to go further and make a nice PCB afterward...QuoteYeah, it's also my approach in life in general.... the more money someone tries to steal from me, the more suspicious and reluctant and demanding I become !QuoteI like how life likes to surprise you sometimes !To be fair I highly doubt he has any clue about the value of this QUAD 33 ! He told me it was a NAD not a QUAD, to begin with !To him it's just old junk he wanted to get rid of... and as he said, he was happy to give it all to me to make use of and enjoy in one way or another, rahter than resorting to dump it all. He said he was kinda sad we didn't meet just a short while ago as he dumped 100 times more stuff, and has only a tiny bit still left to give me ! Yeah, he seems a kind person, I quite like him even before he gave me this valuable QUAD 33 !Well, as I said, with the missing button it's probably not worth much anymore sadly. Not that I intend to sell it anyway.. now I know it's valuable, I want to keep it !Will service it and see if I can get it going again.QuoteYeah I am always happy to hear from you and Shakal, you know your stuff and are passionate, yet not audiophools thanks to your technical/electronic background. So I always enjoy learning from lots of stuff you two, 1st class knowledge served on a silver plate, can't complain I have it easy !Keep it coming !OK let's work a bit on the transport, see if I can get it going or not... that will be for tomorrow... 23H40 here again, time flies, still haven't had dinner, too late now, straight to bed !

author: Gyro
author_rank: Super Contributor
timestamp: April 15, 2021, 09:42:05 pm
content: Quote from: Vince on April 15, 2021, 08:36:17 pmIt is indeed a small world!

author: Vince
author_rank: Super Contributor
timestamp: April 16, 2021, 07:51:13 pm
content: OK, let's be quick... 21H00 here and must go to work tomorro morning at 5AM, so alarm clock set at 3H30 AM ! I should already be in bedSo quick...Worked a little bit on the player this evening, on the CDM this time.1) First tried to oil the top bearing of the pickup... to no available : somehow I just cannot find my bottle of machine oil ! Now I understand that my bench right now is a complete cluster fuck, I get that but still, it's big enough that I should be able to see it eh ? I swear I saw it yesterday just standing right in front of me by the scope.... but spent 15 minutes searching for it, no luck. It just has vanished in thin air, I am baffled... I am sure it's right there looking at me, screaming " Hey I am sure, can't you see or what ?! ". I am sure.2) So next item on the list, was to check the blue Philips cap on the laser drive. Cut on leg of it so I can measure it reliably. Was nto disappointed. As you suggested these caps like to lose capacitance, indeed ! Supposed to be a 47uF one, measured at 20uF !So happy to have found the problem, I replaced it with an equally old one from my stock, but not regular radial one not a Philips of course... and it measured at 51uF so I called it good enough, at least for a quick test. It's only rated at 16V when the Philips one was rated at 25V but since it is fed by the TTL output of the decoder chip, I very much doubted that it would see anywhere near 16V anyway. Not ideal OK, but still, for a quick 2 minute test, good enough. Was very disappointed when I tried to play a CD and it made no difference whatsoever !3) So next item in the list was laser drive. I moved the laser adjustment pot just a hair CCW, and it made things worse. So turned it CW a hair... now works just fine, I have audio coming out !!!Maybe during shipment the trimmer got disturbed a tiny bit, enough to upset the player.However I am not happy about the fact that it turns out that the trimmer is turned ALL THE WAY CW ?!I only barely moved it to get the drive to work, I swear, so that means it was already 98% turned CW.. strange ! I guess it's designed so that at the factory the player works with the trimmer set about half way, would make sense no ? Maybe some douche bag "serviced" this player in the past, " screwdrivered " it, worn the laser out doing so, so now you have to turn up the power to the max just to get enough laser output for playback to work ? Hmmm... not looking good. Poor CDM is on its last leg then, I guess. .. could die any day, makes me sad.Anyway, there is still one BIG problem with the CDM :it works.... but only for 2 minutes at a time ! Ever encountered something like this guysI mean, it does a weird thing, here goes :1) Press PLAY, starts on the button, plays music just fine.2) After a couple minutes or so, sound cuts out abruptly. No skipping whatsoever, it just cuts out all of a sudden3) Then the turntable motor loses its mind and the disc starts to accelerate, accelerate, like a jet engine wannabe4) After a couple seconds, the disc stops, fast (brakes are applied).At this point, I can press PLAY again, immediately, and the player will play the music just fine, as if nothing weird at all had just happened !... but after a couple minutes again it will speed up the disc, then stop it... then I can press PLAY again and the cycle repeats !It is very repeatable. I didn't time it, but it feels like it always takes the same amount of time for it to cut out and accelerate the disc. At a rough guess I would say 2 minutes or so. Could time it if need of course...Also, I swapped transport, and the black one for the Toshiba, does not misbehave. I let it play for like 10 minutes, changing tracks from first to last, then back to middle, to try to upset it... but no, it just works.So, the white CDM is most likely at fault, not the main board. Making progress none the less !At least now I know the pickup is probably just fine (other than the laser being close to dead), since it plays fine for 2 minutes, then plays fine again as soon as I press PLAY again just after the mishap.Also, even if the pickup was somehow showing this weird behaviour, it still would not explain why the disc speeds up, would it ? I mean if I were the decoder chip, and the pick-up was sending me garbage... I would just stop playback and stop the disc, that's all... how would accelerating the disc make things any better !So, my first guess is that the problem is not the pickup, but simply the turntable driving chain that's bad. OF course it's all a closed loop, everything is interdependent, I get it but... since we know the problem lies in the transport, not the main board, and since the pickup works fine for the first 2 minutes... my bet would rather be on the PCB that's at the back of the CDM, since it controls the turntable motor, and nothing else. Service manual gives the schematic for this board. There is plenty of stuff on there, so one of the components must be bad.. would you agree with me, thus far ?!I could swap the control board with the black / Working CDM to confirm this. Had a look, looks quick and easy and does not disturb the alignment of the pickup. It's well separated, great.If it is confirmed that the board is bad, then I can start to trouble shoot this board. There is a lot of stuff on it so could be anything.. 4 op-amps, 4 bipolar transistors,, a dozen resistors, 6 caps but all sub uF / low value ones, so probably ceramic or film, not troublesome electrolytics. Still, have seen film caps go bad, an ceramic caps as well, given the right circumstances.....but there is also I see, two HALL EFFECT sensors ?! Hmmmm.... these things do go bad, in general... don't know about CD transports, but they sure go bad in laptop computers where they detect the closure of the lid, and they sure go wrong in the ignition system of all my old cars !Now, the fact the the problem has a definite "timing" aspect to it, fails after 2 minutes, every time, then "reset" itself once the motor is stopped and I press PLAY again....I guess excludes any thermal effect ? I mean the timing would be more random I guess. Plus, it probably could not reset itself so fast, pretty much instantly. So it looks to me as if this timing aspect would more due to a capacitive thing going one somewhere, that would be reset once the main board cuts power to the control board. So one of those small caps might be very leaky or something.I really don't know, trying to make sense of this weird behaviour is not easy with my very recent and limited experience.... so please speak up my dear friends, tell me your thoughts !Hmmm. ... just thinking of the laser drive circuitry. Guess I was wrong, laser output pin of thje decoder is probably not logic level, has to be analog and varying since it's in a closed loop using the "monitor" diode. So yeah maybe the trimmer being all the way CW to get normal operation is not necessarily a worn out laser, maybe it's just some problem in the driving circuitry, something is off, causing the trimmer to have to be fully CW even with a healthy (enough) laser. Worth investigating... though it won't cause my main problem discussed above, so I won't spend on it for now. Fix the control board first.. laser driver second.Anyway, please tell me your thoughts on it as I could really use your help !Now rushing to bed, almost 10PM already, not much sleep left for me, oh boy, gonna be tough getting up at 3H30, ohhhhh dear ....

author: Gyro
author_rank: Super Contributor
timestamp: April 17, 2021, 10:21:15 am
content: Well getting sound is an excellent step forward.It sounds as if you have one known good (black) CDM4 and one suspect (white) CDM4. I guess this gives you the choice of players for a project - the Toshiba if you want the CD373 style I2C front panel interface, and the CD371 if you want the simple front panel interface. I fully understand that you would like them both working.I too would have hoped that the axial capacitor would have corrected the problem. Yes, I would have expected the laser current pot to be somewhere nearer the mid position for normal operation. The only way to accurately set the current, of course is to follow the procedure on page 4-2 of the CD371 manual - setting the voltage across resistor 3508 TP1 and TP2 to be 50mV and then doing the fine adjustment. I would strongly recommend this if you decide to swap be Black CDM4 into the CD371 to avoid blowing the laser due to over-current.The spindle runaway symptom is a curious one. All of the normal causes would be main PCB based rather than individual transport related, for instance, losing the 11.2896MHz clock from the SAA7220, or maybe a DRAM chip fault. It sounds as if the 6805 microcontroller f/w is detecting the runaway and stamping on the brakes. I suppose it might be caused by loss of data but I've never seen it!I suppose an intermittent ribbon cable connection from the main PCB to the brushless motor PCB might cause such a problem, but it's difficult to think that instant recovery on pushing the play button would be so repeatable,Yes, you should be able to swap the brushless motor PCB between the transports - I've never done it, but the mounting pillars of the bottom bearing bracket are a close tolerance fit into the matching holes in the transport, so it shouldn't cause misalignment. It is a 4 pole motor with 2 hall devices. It if difficult to think of a fault that could make it run away rather than stop. The only adjustment pot on the board is a control voltage sensitivity pot, but I think if that went open circuit, it would cause the motor to stop, not run away. Those hall motors are very reliable though.The Marantz CD75 Mk2 service manual includes checking procedure for the brushless motor, with waveforms and measurements (and pot setting) on page 4-5. Don't ask me why, of all the manuals, they decided to put it in just this one manual - or how many years it has taken me to notice it!It is downloadable fromhttps://www.freeservicemanuals.info- it's actually listed as the Philips CD75 MK2 (in keeping with the very intimate family!)...https://www.freeservicemanuals.info/en/servicemanuals/viewmanual/Philips/CD75MK2/None/None/482272522118/.My gut feel though, is that the White CDM4 has some sort of laser pickup problem. Try closely following the laser adjustment procedures by the book. If you can't achieve the stated values, then it's laser is probably dying. I will include my usual warning about ESD on the flexi-print ribbon when hanling the transports!On the upside, it is possible to transplant the laser assembly from a cheap CDM4/19 equipped player - I wouldn't be surprised if you already had one in you now considerable collection!

author: shakalnokturn
author_rank: Super Contributor
timestamp: April 17, 2021, 01:23:22 pm
content: Otherwise a spare is available here:https://www.leboncoin.fr/collection/1814733077.htm?ac=206978287No clue about ESD precautions though.

author: Gyro
author_rank: Super Contributor
timestamp: April 17, 2021, 03:56:30 pm
content: That's a good price, I think that is from a CDM2 transport though (the Marantz CD45 used a CDM2/29). Not a show stopper, and good value considering that it includes the servo board that is built into the CDM2/29. Useful for spares.There are a few main board component differences between using the CDM2 and CDM4 due to different laser/monitor diode and focus coil sensitivities. These are documented nicely in the CD471 /00R/00B/01R/05R/07R service manual (specifically) which covers the transition period between the use of the CDM2/10 and CDM4/11 in the CD471. If you look at the top right corner of the servo schematic page, there is a table of component differences (marked **) - it's a useful general reference for converting other players between the two transports. You will be able to find all the necessary passive components on the servo board in the listing.You can find the relevant issue of the CD471 service manual here...https://elektrotanya.com/philips_cd471.pdf/download.htmlOf course, this makes it impossible to do direct swaps back and forward between the two.P.S. I did actually wonder earlier whether the end-stop position of the laser adjustment pot on the CD371 with the white CDM4 might be due to some mismatch with the main PCB expecting a CDM2, or the white CDM4 being fitted with a CDM2 laser, or some combination (if that isn't too confusing!). It would be worth double checking the relevant component values on the PCB - for instance, the pot value and its series resistor are one of the differences.

author: Vince
author_rank: Super Contributor
timestamp: April 17, 2021, 05:45:56 pm
content: Thanks again chaps for the infos and links. Good find Shakal for the spare parts...Quote from: Gyro on April 17, 2021, 10:21:15 amOh yes I definitely like the Toshiba very much, have grown fond of it already. So I will do everything I can to get the white transport working so I can get both players in business. It is completely out of the question to use the Toshiba as a parts unit to keep the Philips going....QuoteAcutally from what I understand, the " fine " adjustement is precisely setting that 50mV...I meant to do it, but problem ! As you can see i the manual... the adjustment is intended to be carried out by playing a TEST CD, so with a particular audio content. Presumable a single / sinusoidal tone, of god knows what frequency and amplitude. Or maybe it's wide band white noie, who knows. Point is, it's not made to be performed by playing some random music... so I am screwed right there, Bohemian Rapsody just won't cut itAlso, they say 50mV, but 50mV WHAT ? DC ? "RMS"/sine calibrrated cheap DMM ? or TRUE RMS ? Peak ? Peak to Peak ? using a scope then ?!At least the procedure makes it clear that the base position for the trimmer should be about midway, so there is definitely something fishy about my player.QuoteYes been thinking that too. Could easily figure it out though : with the black CDM in place, I could just set the trimmer to see at what point it start skipping the audio ? That would mean that this particular position of the trimmer is where the laser is safe, barely getting enough juice to work properly ?If even the black one rrequires teh trimmer fully CW like the white one, then most likely both pickups are fine and the problems on the main board... but again as said previously, without the test CD and more precision about what they mean by "50mV", adjusting the trimmer would not be pertinentThe spindle runaway symptom is a curious one.That's my luck ! You have 100 times more experience than me yet somehow I get an obscure fault that even you have never encountered !Well, OTOH it makes it an interesting one to troubleshoot then, we will all learn something from it !I suppose an intermittent ribbon cable connection from the main PCB to the brushless motor PCB might cause such a problem, but it's difficult to think that instant recovery on pushing the play button would be so repeatableYes, bad connection would not be repeatable like clock work...QuoteHmmm.... there is a one, full page about this in the CD371 service manual, haven't you seen it ?! It's almost at the very end of the manual. Page 44 out of 46.QuoteI guess it's not impossible... start with the most plausible causes failure before resorting to fancy exotic explanation... dying lasers being such a common thing on these old players, I guess it's good starting point...We could for example imagine that the laser being on its last leg, based on the trimmer being fully CW, maybe after 2 minutes of being powered, it heats up and that disturbs it somehow, and takes away its last breathe of light. Then the player stops the disc and cuts off the laser, so it cools down and then the cycle repeats again. Since the junction of the laser is obviously tiny, it could explain that although its a thermal issue, the time scale involved is fairly short.This, I can investigate. Again playing with the trimmer with the black trimmer will tell me if the trimmer fully CW is due to a worn out laser on the white CDM, or a problem on the main board. If I had a transparent disc, I could check if the laser goes of by itself when the sound cut occurs. No transparent CD here though... But maybe I could hardwire the base of the transistor to Vcc to keep the laser powered up artificially, in the absence of a CD. I don't know...QuoteOh no ! Still have not thought of buying paper clips !!I try to be as careful as can be though, of course. Just before pulling the cable, I ground both my hands by touching the BNC connectors on my scopes,then when I pull the cable I make sure I never touch the exposed metal / terminals, with my fingers. Once the transport is out, I grab my pair of tweezers, I ground that hand again via the scope, then I short all the pins on the flat flex using the tweezers. Then I set the transport aside.Yes, I really WANT to buy paper clips, but every time I got to the supermarket I fucking forget !!![quote}On the upside, it is possible to transplant the laser assembly from a cheap CDM4/19 equipped player - I wouldn't be surprised if you already had one in you now considerable collection!Hmmm.... taht would be useful indeed ! I do have a couple Technics players (the ones with the " MASH "DAC), which do have swing arms in them. They are definitely looking more recent than then old Philips 371 so I guess the CDM must be the one your referring to ! Will check shortly....

author: Gyro
author_rank: Super Contributor
timestamp: April 17, 2021, 07:22:01 pm
content: Quote from: Vince on April 17, 2021, 05:45:56 pmYou're right, the 50mV is the fine adjustment (I was mistaking it with the fine focus) - the master is beginning to make mistakes!From memory, this is a DC measurement. In the absence of the Philips test disc, you can just use a decent quality audio CD (data is data - you won't get problems with strong modulation on Bohemian Rhapsody it will look the same as any other signal). The test disc just a 'standard' for the reflectivity of a normal CD. Just make sure you don't use a CDR, that would definitely give the wrong value due to different reflection. You could try a few audio CDs and check that the reading is in the same range. The reading needs to be correct on Audio CDs anyway - these are what it spends its time playing, not test discs.QuoteThat's the spirit!QuoteI am indeed slipping! I must have seen it in the past, but was looking through the CD75 the other day and noticed it among the tests and adjustments in the front of the manual where I hadn't noticed it before. It's not normally something that you need to go looking for with these motors (my excuse anyway!).QuoteNo no!... pulling the transistor base high will put maximum possible current (limited only by the safety resistors) through the laser, it will guarantee that you find the blown laser that you are looking for! The TDA5708 regulates the Laser current (via the transistor) based on its input from the laser monitoring diode (the laser current pot works by reducing the current from the monitor diode that the TDA5708 sees).Do you have a stack of blank CDRs anywhere? These normally include a transparent disc at the top of the blank discs as protection. That's where I got mine from. Unfortunately it won't help you see the laser output at the point of failure though (it is obviously producing output when you first press play).You could try using the 'service positions', unfortunately you may be hampered by lack of working display. If you read carefully, it seems that in service position 1, the laser will stay on after pushing one of the <<search buttons. These may allow you to keep the laser illuminated long enough to observe the failure. Make sure you view the laser from a distance, nowhere near the focal point, that dim red glow is very bright in the IR spectrum. Another idea is to watch the output of the laser monitor diode (maybe tack a wire on at the laser adjust pot). You may be able to see the diode output reducing, or more likely, suddenly drop as when the laser control loop is no longer able to maintain output.QuoteAs long as you are taking reasonable care, you should be ok. The Laser does have a capacitor and resistor across which should provide a little protection. I'm not sure how sensitive the photodiodes are though. The problem is that once the transport is out, it is mostly plastic so it is difficult to find a decent ground reference before touching the ribbon.Good luck with the CDM4 search!

author: Gyro
author_rank: Super Contributor
timestamp: April 17, 2021, 08:00:58 pm
content: Just a couple of thoughts.1. The spindle runaway. Once in play mode, the SAA7210 will try to maintain its FIFO (held in the DRAM) as about (I think) 75% by adjusting the spindle speed to bring in more or less data. If data stops, due to the laser dropping out, itmightramp the speed up to maximum. I don't know what the microcontroller does in this situation and how it decides when to hit the brakes.2. If you like the Toshiba so much, you could use it as the basis of sound quality improvements (the schematic is the same as the CD371 in all quality relevant aspects), there is no difference. You can of course delay this until your other equipment is improved to the point where it makes a difference. The CD371 is most useful when implementing your own player as a project.

author: Vince
author_rank: Super Contributor
timestamp: April 17, 2021, 08:42:57 pm
content: OK, just spent an hour fiddling with the player. I think I nailed it. You were right, looks definitely like the laser/pickup on the white CDM is on the verge of dying, on its last leg, last toe even. Here is what I did, which led to that conclusion...1) swapped control boards. Takes literally 30 seconds, it does not interfere in away way with the delicate assembly of the pickup, so no risk whatsoever to screw this up, even a child could do it. I put the good control board from the black CDM, into the white/faulty CDM. Result : played fine for 5 minutes, was looking good but....then got a very scratchy sound for a few seconds (sounded just like a 30 year old dirty volume knob or something...), then sound became normal again, then shortly afterwards it did its usual thing, sound cut out, discs speed went through the roof, and then it stopped. This alone is interesting... it did stop, but unlike yesterday where it would fail after a couple minutes, here it took a little bit more time. So it's not that repeatable after all.So looked like the control board was not at fault... hence has to be the pickup somehow, as you suggested. Tried to wind back the trim pot for the laser adjustment. It was 100% CW, but backing it just a split hair made it stop working. It really needed to be 100% to work, and even then I still got that scratchty sound at some point. So might suggest a worn out laser...2) So, I then swapped CDM. That is, I installed the black CDM with the control board from the white one. Would it fail then ?Laser trimmer was still set 100% CW. At first it was weird : the CD was detect properly, the player would play it, disc was rotating along happily, looked all normal except... I had NO sound coming to my headphones whatsoever ! Eh ?! Player seems happy with the plckup since the disc is spinning normally...so why no sound ?! I then started slowly turning the laser trimmer CCW to see if that CDM too needed 100% trim, or not. Answer is : NO !!!As the CD was spinning with no sound, as I was winding back the trimmer, at some point sound came back !!!So I guess the laser was over driven and the eye pattern must have looked all clipping and saturated or something ?! Then I kept turning the trimmer CCW until sound would start having problems. At some point it started producing the same scratchy sound that I had before with the white pickup. So looks like this player does not skip the audio when laser is too weak.. instead it makes this scratchy sound. Why not...Point is : it started becoming scratching when the trimmer set about .... MID WAY !!! YESSSS !!!!!So clearly the driver circuitry on the main board is fine, and a decent laser works fine at about 50% trim, no worries. Slight nuance : there is some "hysteresis" to this... I mean : at 50% trim, the CD will NOT play, won't detect teh disc. Need to increase the trim a bit, I don't know 75% maybe, far from 100% though. Same thing when I try to change tracks : at 50% trim I often run into problems, player can't manage and stops the disc. So in practice I have to set it to more than 50% to have ti detect/start discs reliably. Still, sounds reasonable to me... 50% is for a brand new laser, this one is 30 year old !! And it still plays fine at 50%, needs the extra turn only for detection and track changes, won't blame him ! No ? What do you think ?!3) Once I had rewind the trimmer to halfway or thereabout, and started getting that scratchy sounds... I rewound it even further, very slowly, to see what would happen. Glad I did : guess what happens if you do that and you lose the signal for good ? YES, player spins the disc super fast then stops it !So this behaviour was indeed indicative, at least on this particular player, of a weak/lost signal !!!So with all that, I came to the conclusion that both control boards were fine, and it's just a completely worn out pickup on the white/Philips CDM.Will look inside my two Technics players to see what reference CDM they use, and report back. You will tell me if I can plug them safely into the little Philips...Anyway, making progress so quite happy despite the bad news !

author: Gyro
author_rank: Super Contributor
timestamp: April 17, 2021, 09:02:22 pm
content: Good test strategy - it sounds as if you have a good handle on the situation now, particularly the runaway effect of insufficient laser output (I don't think I've ever wound one back that far during operation). I would beware of running the black one at the end-stop any more though, it will probably shorten its life. Yes, too much power will probably cause the photodiodes or input circuitry to saturate.Good news on the motors - I think you can probably see what I mean about the size of those shafts compared to the average brushed motor.

author: Vince
author_rank: Super Contributor
timestamp: April 17, 2021, 10:42:42 pm
content: Quote from: Gyro on April 17, 2021, 09:02:22 pmWell yes of course ! Now I know it works fine somewhere between 50/75%, not going to burn it at 100%.... plus that will never happen anyway : now that the diagnosis has been established for the Radiola / white CDM, I don't have any reason to mess with the good black one from the Toshiba : So I put it back inside the Toshiba whee it belongs, and put the Toshiba player all back together ! While I was at it I put some contact cleaner in the tray switch taht was causing me random weird problem the other day.. and exercised the switch 100 times by hand. Should take care of the problem, we shall see in the long run. Gave it a test ride, seems to work fine. Just love this player, don't think I want to mess with it. Will rather use the Radiola as a test bed. Needs a new pickup anyway already, and extensive work to get the display running again. So... it's already going to be Frankenstein-ized anyway, so might as go the extra mile and use it as a test bed for audio improving mods like the two of you have made.QuoteYes, generally speaking these brushless motor inspire so much more confidence than the shitty tiny skinny brushed ones. Plus the brushless look cool (how scientific is that for an argument !) and beefy, indestructible, and easy to take apart, and larget diameter. They probably have more torque than the shitty brushed ones. And that one piece cast resin piece is nice too, especially sexy in white. I can't get enough of looking at it. There must be something weird in me... or maybe that's what it is to be a "nerd"So be it, I am what I am ...Anyway, with the Toshiba all buttoned up, I could free some space on the work bench.... just enough to lay my two swing arm Technics players.See picture.... they are similar models but not the exact same. The tray mechanism is 99.99% the same as the old Philips, incredible. Only tiny difference so as to accommodate the mounting points of the later CDM transport, but that's about it ! So for example I could reuse the tray, tray switch linkage pieces, motor, gear and belt to fix and old Philips !QuoteGood !!! Just checked my Technics players, they both have that CDM4/19 in them !!!Looks indeed like shittier construction, and shitty looking brushed motor... but the swing arm and pickup look like a carbon copy of the CDM 4/11 indeed !So.... time to swap swing arms with the Technics.... tomorrow !Good night....

author: shakalnokturn
author_rank: Super Contributor
timestamp: April 17, 2021, 11:28:17 pm
content: I suppose the runaway is what you get when the SAA7210 can't recover the clock correctly from the input stream. I don't know why it would react specifically that way though.On other players I've noticed that you can often trigger the speed runaway by getting the VCO adjustment too far off.Agreed that the laser seems to be on its last leg, all the same in case it came from a smoky environment (any brown/yellow deposit if you wipe the tray with IPA? No not beer!) you may want to re clean the lens or as a last attempt remove it to clean the under-side and prism. I can remember doing it on a swing arm model before, can't remember which though.

author: Vince
author_rank: Super Contributor
timestamp: April 18, 2021, 12:00:18 pm
content: Cleaned it again, still get the scratchiness every now and then, but it's been running for 20 minutes so far, and still going so...not dead but not trust worthy either to me.... Still, working plenty well enough to now let me turn to the display problem, that's for sure.Not a smoker CD player it seems, no residue when cleaning the CDM, and all the white plastic parts in the mechanism, all look brand spanking new, snow white... whereas in the Toshiba all these parts are significantly yellowed.I just checked the eye pattern from the white CDM so I have a reference point so I can assess the improvement (hopefully) when swapping the swing arm with a CDM 4/19. Glad I did.. see below.Used a x10 probe. Laser trimmer again set to 100% or else it just won't work as per usual. This results in a roughly 2Vpp signal, which is excellent given the service manual suggests "around" 1.5Vpp. Now, from working on a previous player, can't even remember which one, posted it on EEVBlog though (maybe the CDM12.1 I replaced in my dad's 3 disc carousel changer from his crappy Philips integrated stereo system) I noticed that I could reduce the laser output A LOT before it would start misbehaving. I remember something like 100mV ! At 100mV the eye pattern was still looking good and still playing fine !Now, with the white CDM here, look what happens (second picture) : 2Vpp at 100 trim. Then I rewind the trimmer juuuuuuuust a split hair, to get it to produce this scratchy sound just before it stops working altogether and stops the disc. See what's the result ? Amplitude has not changed, still a very healthy 2Vpp.. HOWEVER the eye pattern becomes extremely blurry, can't even see it anymore, it's like a fuzzy cloud, an aurora borealis or something !So the problem is not a weak HF signal, it's strong (needs 100% trim though, of course...), it's a " blurriness " problem ?! Focus problem rather than weak laser?! I guess either way it does not matter... pickup still needs replacing... but the point is to understand what's going on, as much as getting the player working properly and reliably...

author: Vince
author_rank: Super Contributor
timestamp: April 18, 2021, 02:40:31 pm
content: OK swapped the swing arms with one of my two Technics CDM 4/19. Just like the spindle motor control board, it's a 2 minute of a few screws and that's it.With that "new" swing arm, the Philips worked (which is a good start...), and according to the eye pattern, it worked much better, in that although it's tired as well and needs near full trim to be able to detect a disc and switch track reliably, at least when it's playing and you rewind the trimmer so to speak, it does not die instantly with that aurora borealis pattern. Instead, as you would expect, it still plays but of course the HF signal amplitude progressively decreases, but still looks like a clean/stable eye pattern, and at some point obviously it loses sound. It loses sounds at an amplitude of about 1 volt, which is much better than the original arm/pickup. However as said before, although it can still play music fine at this level, its not strong enough a signal to be able to detect a CD when you insert it, or to change tracks. For that, you still need to get near full trim, which gives 2Vpp like the original arm. Looks like 2V must be what the HF amp is capable of producing. Past that point, if you keep turning the trimmer to get the last 5% out of it, amplitude does not increase anymore. Does not clip or distort either. Instead what happens is that the DC offset decreases, by about one volt from where it used to be. So to the sweet spot I guess is to set the trimmer to 95% where I get that 2V amplitude, where the disc detection works reliably, and just before the offset starts sinking.Worked fine then after a short while things suddenly started wreaking havoc. A would lose the HF signal completely, and the pickup/Arm would make a faint " clic clic clic clic "sound indefinitely. Looks like I fried the laser for good eh ?! Yes, paper clips buy I will...So swapped swing arms again, to give the white CDM its original arm back. I set the laser trimmer very precisely using the scope, using the "technique" described above.... and well, seems to work "fine"... for the 30 minutes that I tested it, changing tracks often to try and provoke a failure.So I will leave it at that for now, and now switch to the display problem.Will get that MM5450 in DIP package first, some prototyping board and cobble something crude, quick 'n dirty with just the first couple digits as Gyro suggested. Just as a proof of concept. If I can get that working then that will motivate me and I will get a PLCC version of that chip and go through the trouble of designing a replacement PCB for that module, using the original displays.

author: shakalnokturn
author_rank: Super Contributor
timestamp: April 18, 2021, 03:50:00 pm
content: Until now it sounded like a weak laser, now with your latest measurements I'm not so sure...

author: Gyro
author_rank: Super Contributor
timestamp: April 18, 2021, 04:37:02 pm
content: You're becoming quite the CDM mechanic! I'm glad you didn't run into any problems with the arm swap procedure.I'm with shakalnokturn... slightly confused. It would be really unlikely to get two CDM4s with weak lasers - but please do buy some paperclips! So it is only the CDM from the Toshiba that doesn't require 95% on the laser adjustment pot?1. A couple of random thoughts. Did you check the component values to confirm that the PCB is definitely CDM4 'ready' (values from the CD471 manual)? I'm not sure quite how that would tie in with the various transports but this CD seriesdidspan the transition form CDM2 to CDM4. At least confirm the marked value of the pot.2. In the case of correct playback but inability to initially detect the disc, have you tried adjusting the focus offset? If you do, then carefully mark the wiper position so that you don't run into problems with a tweaking both pots at the same time. I may make use of the baseplate drilling diagram myself - I suspect that it holds for the CD371 too.Now you at least have proper operation then yes, it sounds a good plan to have a go at the display project.Just out of interest, I have attached a project article from Elektor Magazine from back in 1992, which illustrates the way it was possible to purchase CD player OEM kits from Philips. Several small fledgeling manufacturers got a start into CD products this way. I forgot I had this.

author: shakalnokturn
author_rank: Super Contributor
timestamp: April 18, 2021, 08:01:27 pm
content: A couple if thoughts on your last measurements...I'm leaning towards a tracking or VCO problem but it's merely more than an educated guess at this point.Maybe worth checking the small electrolytics around the SAA7210, power supply decoupling and VCO section.Testing the doubtful transport in the working Toshiba could also help further diagnostics. Taking care of not abusing laser power and possible component differences of course as Gyro mentioned.

author: Gyro
author_rank: Super Contributor
timestamp: April 18, 2021, 09:03:50 pm
content: Quote from: shakalnokturn on April 18, 2021, 08:01:27 pmAgreed, I think it's the only way to move forward if you want to be sure of the situation.

author: Vince
author_rank: Super Contributor
timestamp: April 19, 2021, 03:36:14 pm
content: Quote from: Gyro on April 18, 2021, 04:37:02 pmThanks, but that would be a rather shady backyard mechanic then !I didn't observe any procedure for the arm replacement... didn't even think of reading it... thought it was pertaining only to pickup replacement, not complete arm sub-assemblies. My bad indeed.I simply unscrewed the bearing backplate as they call it, and screwed it back on, no more no less, and all went well. I mean the eye pattern before/after is 100% the same... it it were that sensitive, I would have expected wild degradation (or improvement !) of the eye pattern or player behaviour, but saw none whatsoever. Sheer luck ? .... I mean, the procedure says that you can adjust the angle by moving the back plate then securing it into place with the screws. Trouble is that this plate cannot move. It was stuck in place once I had removed the screws. Had to pry it off to get it to come off the CDM ! So much for adjustments....QuoteI am VERY confused... so if you are only "slightly" confused, that's good !QuoteI have to say I was surprised as well that the other arm required almost full trim to be reliable...QuoteI am true to my word. See below.QuoteI don't know what the Toshiba requires. When I tried I was not back then scoping the eye pattern hence not fiddling with the laser trimmer... so it was therefore using full trim too, since it was to that and I had not touched it yet at that time.QuoteJust realized... there is an addendum toward the end of the manual... it gives all the CDM4 specific changes. New main board schematic and new laser adjustment procedure too !The CDM4 schematic does not say what is the value of the laser trim, sadly. However on the first/ CDM2 schematic, it's 1K , and my board I have a 4,7K ! So I guess that means it's been updated for the CDM4 and all ought to be well... ought to.QuoteNo ! ... because I don't have a good understanding of how this trimmer affects the operation of the drive. I don't touch things that I don't understand.... and since you have not taught me that part yet, I carefully avoided messing with it....QuoteI just did !since you talked about it, I somehow considered it meant I was allowed to !Quote.. did not work. All I have is big white tyre marker... it's too big and the ink is too fluid : as so as I touched the trimmer, the ink by capillarity instantly spread all around the wiper shaft, rendering the exercise futile....But since there is a procedure to adjust focus anyway, I though worse case scenario is I screw things up and so what, I just reset the trimmer using the procedure... that's what it's there for after all...so I looked at the eye pattern and turned the focus trimmer a split hair either direction. Zero change. so turned a couple hairs.. still no change.Turned it dozen hairs... still no change. turned it wildly, full lock on both sides.... still no bloody change ! So I just put it back mid-way.No matter how you set the focus trimmer, from 0 to 100%, it does not affect IN ANY WAY SHAPE OR FORM, the eye pattern NOR the behaviour of the drive, ie it doesn't drop sound, no skipping, no disc stopping. Still the exact same performance when detecting CD's or changing tracks... this focus trimmer has absolutely NO EFFECT whatsoever ?!!!Makes zero sense, you will agree... so it's like the trimmer is open-circuit or something.. which is extremely unlikely of course.Maybe some nearby electrolytic cap leaked and corroded/cut a trace related to the trimmer ? Doubt it, the top side of the board looks pristine...[quote}Just out of interest, I have attached a project article from Elektor Magazine from back in 1992, which illustrates the way it was possible to purchase CD player OEM kits from Philips. Several small fledgeling manufacturers got a start into CD products this way. I forgot I had this.Wow that was cool, thanks !Didn't know about such things ! I doubt any major manufacturer would do that today... that was very nice from Philips indeed !!!That said, by the time you have added the time and money required to R&D and build prototypes, then your own final product... you would be better off buying an off the shelf player I suppose ! But still, it would the DIY guy to design his very own unique player if he fancied that.

author: Vince
author_rank: Super Contributor
timestamp: April 19, 2021, 03:48:49 pm
content: Quote from: shakalnokturn on April 18, 2021, 08:01:27 pmYes I think it's time to pull the main board so I can inspect it closely on both sides. Check for corrosion/leaked caps, and whatnot.Time also to check the basics : all the power rails. Maybe one is bad and affecting the performance and operation of the big analog chips.Worth recapping all that area of the board. Not that many caps anyway so should be fairly quick and cheap.QuoteYes that sounds like a plan, should tell us some things indeed... will do that. Poor Toshiba, I have only just put it back together... going to strip it again. Not sure he will forgive me.....Will open the Toshiba and solder wires so I can check the eye pattern while experimenting with the transports.QuoteWill take note of the HF signal amplitude with the Toshiba's original CDM, so I can reset it to where it was, after my experiments, then I will set it half way and swap transports.

author: Vince
author_rank: Super Contributor
timestamp: April 19, 2021, 05:34:49 pm
content: OK, live results, Toshiba is playing music as I type this.... soldered wires to check the eye pattern, and checked trimmer position and overall behaviour.In short : easy, it was 100% as the white CDM was in the Philips ! 98% trim... ie full lock then back a tiny bit to get rid of the unwanted offset that appears at full lock, and no more. Amplitude 100% same as well : 2Vpp. Behaviour too : if I try to go 100%, additionnal offset appears and playback/disc stops. If I rewind the trimmer, it behaves 100% like the CDM4/19 I pinched from my Technics : I won't get an aurora borealis, but rather I will get the expected progressive drop in signal amplitude, until it starts making this scratching noise then stops. Level wise, again 100% like the Technics : it stops working when I get to about 1Vpp.So looks like the Technics was 100% fine until it died suddenlyAlso show that the Philips laser trim set at nearly full lock is not that weird....Also, check the manual, the CDM4 addendum. Revised procedure for coarse/baseline adjustment; you need to measure the total resistance formed by the trimmer and its series resistor. The latter is 100ohms and the trimmer is 4.7k. so that means the trimmer must be set at 900ohms, that's only 19% ! Take into account the worse case scenario when including tolerances (assuming say 5% for the series resistor and 20% for the trimmer), then that's a 5640ohms trimmer with a 105ohms series resistor. 895 / 5640, that's about 15% !!! So you are already near fully lock CW !Add variations in laser output, then once you do the fine adjustment yeah, being dead close to full lock is not at all improbable, eh ?!OK, so now that I know how the Toshiba performs, eye pattern amplitude and trimmer setting...I can remove its CDM and replace it with the white one.... taking a deep breath... what will we find.... STAY TUNED FOR THE NEXT EPISODE... NEXT WEEK ! In the mean time you can subscribe to my channel and donate on Patreon to support my channel, new cool merch coming soon !No not my kind, all too common these days....

author: Vince
author_rank: Super Contributor
timestamp: April 19, 2021, 05:55:11 pm
content: Due to a rebellion among my Patreon supporters, I decided to unveil the next episode much earlier than I originally meant to. So here goes :What does the white CDM when it runs in the Toshiba ? Place your bets, I'll come back in 5 minutes.......[5 minutes later]So... what does it do.... it does... it does.....100% what it did in its original Philips player, no more no less, carbon copy !I.e. :1) Needs 98/99% trim to work.2) If you just breath on the trimmer to rewind it half a bees dick, it will give you an aurora borealis and cut out/stop the disc immediately, so you don't get to see what the eye pattern would do for lower trimmer settings. Amplitude when working, again 100% the same, 2Vpp, just like the original Toshiba CDM.SO !Looks like the white CDM is not all that bad after all, and that the extreme laser trimmer setting is somehow normal for these players when they got switched to CDM4 in mid air ?What do you think, shall we leave it at that and just take it as a learning experience for the next CDM4 enabled CD371 that we come across ?!Shall we move on to the display problem now, or not ?

author: Gyro
author_rank: Super Contributor
timestamp: April 19, 2021, 08:02:37 pm
content: Quote from: Vince on April 19, 2021, 05:55:11 pmThat's Patreon supporters for you!Well that was quite a stream of posts, lots to digest. your last post seems to sum up the situation well though - the white CDM with / without the CDM4/19 replacement arm behaves the same on the Toshiba and the CD371. That's what we wanted to know, and rules out a lot of potential failure points / differences between the two players.I haven't checked the laser pot position on my CD472 - frankly I'm a bit scared of doing so as the wiper has been in the same position for all of its long life, but I will look tomorrow.I'm wondering if there were some later changes introduced later on in the era of mass market CDM4/19 players to give a more centred pot position, I'll go through my library of SMs. It seems very risky for volume production that there would be so little adjustment range.I think the focus offset adjustment is far less critical, and is aimed mainly at getting initial focus, rather than focus tracking. I have only played with that pot once before, on a Rotel player with definitely dying laser, it had some effect there, but minimal.Your arm replacement procedure, even if humble, seems to have been fine. Theoretically you should go through the whole transparent disc, 'florescent light' procedure, but as long as the spring went back in the same position, I don't think it's that critical - as long as the arm is swinging visibly level, it should remain well within the focus range.I think you have established that the Toshiba and CD371 PCBs are close enough that it rules out any gross fault on the CD371. Of course it may be that neither of them is working optimally and could do with some electrolytic PSU capacitor replacements, but good enough for now I think.BTW, as well as looking at the eye pattern, the other useful indicator is to monitor the EFAB signal from the SAA7210 to the SAA7220 (SAA7210 pin 36 / SAA7220 pin 4). This is the indication of a raw uncorrected error which causes the SAA7220 to go into error concealment (interpolation) mode. You would expect a few pulses on any good CD, but it is a much more sensitive (earlier) indication of things getting into trouble than audible distortion.In short, for now I would agree on 'good enough' and proceed with the display mod.P.S. Well done on finally acquiring the paper clips (yours must be the only home in Europe that doesn't have one hidden down the back of the sofa or a desk drawer!), I hope you have now applied them to all arms not in captivity!

author: shakalnokturn
author_rank: Super Contributor
timestamp: April 19, 2021, 11:10:54 pm
content: On the swing arms swapping:I've done it before too on CDM2's / CDM4's it is easy and there really isn't room for adjustment.If you do the same on a CDM0 or CDM1 you're in for some fun though...

author: Gyro
author_rank: Super Contributor
timestamp: April 20, 2021, 09:15:21 am
content: Yes, they had optimised much better for mass production by that stage. As long as you don't snap the two little plastic locating pegs when you remove the spring plate it's fine (otherwise it gets like the earlier ones!). Gently lifting up the two little metal spring tabs helps you remove it without struggling and gently bending them back down allows them to line up spring against the pegs again.

author: Vince
author_rank: Super Contributor
timestamp: April 20, 2021, 06:25:15 pm
content: OK, so let's move on to the display problem now. Wil order the DIP version of the chip, some decent prototyping board, and do a quick and dirty proof of concept, before spending more money and time for a polished final product. While I am waiting a month or two for that stuff to arrive from china, let's look at the stuff that my new grand pa electronic friend brought to me last saturday, as he promised he would.Well I alraedy told you what he would bring, but now we can have a closer look. Shakal was curious about the monitor, and I want to hear your opinion if any, on the speakers he gave me. Wrote down the info I could find tagged on them.First we have some junk, which I have already taken apart and dumped the cabinets. A huge 5x100W 5.1 amp made by Hyundai, which apparently don't make just cars. Their amp is made as cheaply as their cars, as ugly as well, so I had absolutely no remorse whatsoever taking it apart even though gran pa told me it works. I did not even bother turning it on as I have no use for a 5.1 home cinema amp, and even if I did, I would get something decent... Luckily, despite the ultra cheap design (almost shocking really, was surprised it could be THAT crap, really), it was full of cool things to salvage, not least was a huge toroïdal transformer, a million and half tactile switches for the front panel, some big ceramic packed resistors, a pair of big Nichicon caps, relays... this thins is tremendously more valuable and interesting for its parts than it is as a complete product !Then a couple DVD players. A Samsung and a Hitachi. Actually inside it was not that crap at all, you had your money's worth. The pickup had a cool die cast metal body. I did try both of them quickly, with an audio CD. Perforamance was terrible.Turned out once I was inside, that they used the exact same chassis. So I have two of every board !That's for the junk.Now for the speakers. He gave me 4 of them. Wrote all the details and took pictures. I don't doubt that any of them would be 10 tiems better than my crappy small Toshiba speakers that came with a super low end stereo system.Yesterday after work, paid a visit to the local electronics shop down town, as I am fortunate to have one. I guess one of 5 remaining in France...Bought 5meters of audio cable so I can hook these speakers to my amp. The Toshiba speakers didn't need cables as they came with thier own cable hardwired, coming out of the cabinet.Section-wise, talked a bit with the guy. We settled on a cable section of 0.75mm2. Should be plenty enough for the mere 20% volume setting I am using on the amp.Also bought a 2.5m long RCA to RCA male cable, so I can at last plug a CD player (or anything) under test on the bench, to my amp on the shelves. This way I can have the cable readily accessible on the bench when I need it, and I can just select the TAPE input on my amp to switch to the device under test. Quite convenient, like it.So here is for the speakers.1) A pair of large ones. MAde by " Boston Acoustic", made in USA, model HD9. Guy tried to educate ignorant me quickly. Said it was a 2 way system even though it looks like a 3 way one. The biggest "speaker" at the bottom (missing on one, and broken on the other...), is actually not connected to the sound source, no electrical connection. Said it was called a "passive" speaker. If I understood him well, the ideai is to reuse some of the internal acoustic pressure inside the cabinet, to the front/outside. This was you get a little bit more acoustic pressure outside, so a better efficiency for a given input power. Something like that ?!They are broken and are crap anyway he said, so will salvage what can be, the filter(s), and dump the rest. Might keep the individual speakers though, as they are bound to sound much better than the myriad of crappy small speakers I salvaged from old TV sets and such...2) A single speaker/baffle. Said it's not meant to be used as pair. There is still the sticker from the thrift shop he got it from, which says it's a "central" speaker. Also, the orientation of the logo at the front, and of the sticker at the back, suggest that it's meant to sit flat, horizontally, not vertically like your usual pair of speakers. So I guess it's meant to be used in a 5.1 system ? Not sure what I can do as a lone speaker ? Still have full bandwidth ? It has a Tweeter along with too medium sized speakers, so might do it. Has a port at the back too, as can been seeon on the pictures. Could use it as test speaker for example ? It's decent looking, decent build quality and compact, so easy to store and put on the bench if I wanted to connect it to some piece of gear quick and dirty ? I don't know... kinda cute so trying to find a use for it, a justification for keeping it...Anyway, here is the info : Made by "Studo Lab" 6 ohms not 8, model " Cine 02.2 Cent " . Its name kinda suggest it's indeed for a cinema amp, and does it also implies it's worth only 2 cents ?!Power rating : 150W , yeah right..... Chinese Watts I guess...3) A pair of Marantz speakers : Model HD 493. 70Watts. Designed and Manufactured in the UK, it says. They are very compact. Two way system with a port at the front. Guy said it was called a " Reflex "design ? Said it was meant to tune a resonance at some frequency, so that you would get more bangs for your buck, better efficiency. Same goal as the passive speaker then, but different technique ?Sadly one of the speakers is missing the piece of cloth/ fabric that covers the cabinet. However it still has the frame that snaps onto the cabinet, it's only the fabric itself that's missing. So I guess one can buy standard replacement fabric, and I could reline both speakers with new fabric ?4) Last one. A pair of Technics, model SB-C7, rated at 80Watts. Made in Spain. 3 way system this time, and no passive speaker or reflex port. Just a plain simple 3 ways system.So to sum it up, the sound lad is not suitable as it's central / lone speaker. Boston ones are crap and broken anyway, and too large for my bench anyway. And I don't need big power. So I am left with either the 3 way Technics or the 2 ways reflex Marantz. Any preference ? Will try both. The Marantz is quite more compact than the Technics, so it's got that going for it, as I bench space is at a premium. And it's designed and made in England. Technics are made in Spain !Will try both of them of course, to see, uh, hear them and decide which one I prefer. Maybe one of the is damaged / degraded after years of sitting in his shed, so I won't even have a choice....Now let's end with the monitor, Shakal was curious... turned out to be a good surprise. It's not as crap as I thought it was, from the crappy picture he showed to me on his smartphone the other day. It's indeed a Sony, and indeed a monitor, not a TV. No connection at the back for an antenna, no built-in antenna... just a monitor.Among the stuff he gave me, there is a video camera, looks like a security camera ? Camera is a Bosch model LTC 0455/11 with an LTC 3364/60 lens mounted on it.Monitor is model PVM-9000ME, colour, and with a cool Trinitron tube!!!It's small enough to be portable (has a beefy non fold-able/removable carry handle on top of it), yet large enough to be comfortable, you don't need a microscope to look at it, nor do you need to stick your nose to the CRT.So looks like this monitor is designed to display CCTV camera imagesMonitor has all sorts of weird proprietary connectors at the back, be it for the mains power plug that's non standard, or the plug for the battery pack. Has a DC barrel jack for an external power adapter as well. Input is BNC only, with a switchable 75ohms impedance. Guess that means it can be used as a high-impedance input too ? Anyway, Video stuff uses 75ohms not 50, I know at least this muchIt's so tempting to do a quick test, and power the monitor and hook it to the camera !!!I do have a 75ohm BNC cable, because when I asked my local shop for a coax cable to work on a frequency counter I was repairing, he gave me that cable... once back home I eventually realized it was 75ohms video cable, not 50ohms !!!!The camera has quick connect power terminal : just shove a bare wire in it, press a tab, and it locks the wire into place, convenient. Needs 24V AC or 12V DC. Could easily power it with my lab power supply, then.As for the monitor, easiest I think is to power it with mains voltage, with a couple crocodile clips in the power socket... I like to live dangerously.Will try to do that this evening, stay tuned !

author: Vince
author_rank: Super Contributor
timestamp: April 20, 2021, 06:27:34 pm
content: Sony Monitor and Bosh Camera.

author: Vince
author_rank: Super Contributor
timestamp: April 20, 2021, 07:02:54 pm
content: YEAH, RESULT !!!Shoved two wires at the back of the camera, connected to my lab power supply, 12V DC, draws 250mA or so. Thought hell, I can check the camera by itself, no need for a monitor just yet... I can just hook the camera straight to the scope and see what I get !I get a nice composite signal, appears to work, it's alive !!!Scope is looking at itself albeit its composite self !I like the composite video signal, sexy waveform, and looks so cool on an analog scope, could look at it all day !

author: Gyro
author_rank: Super Contributor
timestamp: April 20, 2021, 07:04:48 pm
content: Quote from: Vince on April 20, 2021, 06:25:15 pmYou're ordering a salvaged e-waste MM5450 from China?

author: Vince
author_rank: Super Contributor
timestamp: April 20, 2021, 07:07:27 pm
content: Quote from: Gyro on April 20, 2021, 07:04:48 pmGoogled the chip and only results were from shady Ebay and Amazon etc, none of the major retailers like Farnel etc... do you mean you managed to find one from a trustable / reputable vendor ??

author: Gyro
author_rank: Super Contributor
timestamp: April 20, 2021, 07:13:46 pm
content: Strange, they're available brand new from Farnell, RS etc. here...https://uk.farnell.com/microchip/mm5450yn/ic-led-display-driver-5450-dip/dp/2510523?st=mm5450Also a couple of ebay sellers here. Actually cheaper than Farnell / RS for a new ST M5450 (makes a change!).https://www.ebay.co.uk/itm/1-M5450-34-segment-LED-driver-IC-MM5450-M5450B7-MM5450N-5450-40-dip/280329718174I don't know if they ship to France.

author: Vince
author_rank: Super Contributor
timestamp: April 20, 2021, 07:43:00 pm
content: Oh yeah you are right, looks like Google is being paid by Ebay and Amazon for returning only their results and ignoring the main vendors !Just checked Farnell and TME, they both have it, in stock, and both the DIP and PLCC versions !Thanks for waking me up, never trust Google, check by yourself !Farnell is abusing, selling the DIP version at 6,17 Euros before tax, so way more expensive than Ebay. But still affordable of course. They carry 3200 DIP packages in stock !and only 500 of the PLCC one. Clearly someone at Farnell is thinking... they must check Ebay to see what niche market there is for such or such chip, among the DIY electronic people, and they decided to sell that chip ! No small business I guess.Somehow, TME which is much smaller than Farnell, sell this chip for way less than Farnell !Only 4,30 Euros (before Tax again), for the DIP package and only 3,14 Euros for PLCC !Hmmm... TME here I come ! Need to order some bits and bobs as well for another project, and also I broke my Weller soldering tip, need a new one. Just need a pack of cheap but decent FR4 prototyping boards, but this kind of stuff usually is prohibitively priced unless you go to Ebay and co. So these may take more time to come. Will try to find some from a local / European vendor so I can get them fast.

author: Vince
author_rank: Super Contributor
timestamp: April 20, 2021, 08:15:55 pm
content: Cool for the chip, looks like there will be some action much sooner than expected in the display department then !!!Plugged the camera to the monitor... was easier than expected, because turns out the weird mains socket is not proprietary after all !It's strange one that I now recall seeing, once... just once before. It's a 3 wire version of the slim 2 / flat 2 wire standard plug you get on any domestic appliance... like the CD players fdor example ! So grabbed a power cord from a CD player on the bench, plugs right in ! The earth pin is just not connected of course, but the power cord plugs in that socket perfectly !So that was cool.Excellent surprise, monitor works just fine, and picture quality of the combo camera + monitor is excellent ! Does not show on mly pictures of course, since my camera does not play well with CRT of course, but you will have to take my word for it. In the second picture I take a close up shot of the power supply feeding the camera, and the picture on the screen is as sharp and real looking as I can see it with my own set of eyes ! Looks superb. Actually picture looks truly exceptional for macro shots like this, but looks crappy / bluury from a distance. Maybe I could help it with the two controls available on the lens, but sadly one of them is broken. The screw snapped when I tried to un do it. So there must be a couple threads stuck inside, that keep the control from movingThe " W -- T " control works. IT's the other one marked " N --- [infinite symbol] " that's stuck to the " N " end of the adjustment range.The macro performance is so good that the camera can focus with perfection onto the imperfection embedded on the objective lens itself !!!Monitor has PAL / SECAM setting, so I guess the camera must use one of these protocols...Not versed into video stuff as you have gathered, but I get a picture regardless of the setting ! The only difference I can see is that when setting the monitor to PAL, I get a colour picture, and when I set it to SECAM, it is forced to black and white. Other than that...The monitor of course is not brand new, so every now and then it goes haywire and I lose the picture. I guess some caps need changing in there, and some solder joints looked at ?!.....But basically it works, camera has fantastic macro capabilities and that Trinitron tube is s sharp, a joy to look at.I am definitely keeping these two !I already have a use for it ! I was given for free an oold portable HP serial protocol analyzer (HP 4951C), with a built in keyboard, floppy disk and a tiny green CRT.. that's completely burnt out !But... the unit has a BNC output at the back for an external monitor ! From memory it uses some weird protocol but after some research, it's pretty much compatible with the american NTSC standard. Voltage levels may differ that's about it. If I can find an NTSC to PAL / SECAM adapter for chip on evil bay, I could maybe get it to display on that cool Trinitron monitor and the picture would be so much better and so much larger.

author: tautech
author_rank: Super Contributor
timestamp: April 20, 2021, 10:16:49 pm
content: Nice scores Vince.Certainly the Marantz vented (reflex) speakers will be the ones to keep but the Technic's should be OK too providing none of their bass speakers haven't been damaged from too much power.The Sound Lab unit is certainty a centerfrontspeaker for use in a surround sound setup.

author: shakalnokturn
author_rank: Super Contributor
timestamp: April 21, 2021, 12:59:07 am
content: Cute monitor looks early 80's, see now you've turned it on you've softened, should have taken it apart first!I'm curious on your conclusions listening to the speakers, place them with tweeters about head level and not right against a wall (placement can make a whole difference in sound) make sure you get the polarity (phase) same on left and right sides.I've heard some very good 2 way speakers but usually prefer 3 way, the improvement is usually obvious when listening to brass instruments.A pity for the Boston's they looked decent too... The rest is awful but could still have it's sacrificial use for crash-testing amplifiers.

author: Gyro
author_rank: Super Contributor
timestamp: April 21, 2021, 11:01:12 am
content: Yes, some reasonable speaker finds. I don't know anything about the Technics. The Marantz ones probably sound warm and laid back. Boston Acoustics were (are) a name. The probably have decent tweeters and midrange drivers. You might try looking for a pair of low cost woofers - the remaining one should give you the impedance. Having a midrange driver should ease the quality requirements on the woofers.Edit: Sorry, I didn't read your post properly, I didn't realize that the Boston ones had passive radiators - also known as Auxiliary Bass Radiators (ABR). They take the place of a reflex port, with controlled mass and resonance. You could try blanking the holes and experimenting with different lengths of plastic pipe as a substitute (or stuff the holes with a sheet of high density foam).

author: Vince
author_rank: Super Contributor
timestamp: April 21, 2021, 10:06:50 pm
content: Quote from: shakalnokturn on April 21, 2021, 12:59:07 amYes, you are 100% right. I have softened. I am not proud of that. I must work on that, so that it never happens again. Take apart I must.QuoteAsking me to comment on audio stuff is like asking my mum what she thinks of Shannon's theorem. It's not really relevant...I know squat about audio and don't even possess the vocabulary to describe how I feel about this or that aspect of the sound. I am both utterly incompetent, as well as being unable to convey my thoughts so....But well, somehow I do have some feelings so I will try to explain them. Feelings, not scientific facts...First, I took apart the broken Boston. Broken and too big. I have run out of space in the house, and am not looking for a speaker "project"....I accompanied them to their last house, the dump yard. Of course I salvaged everything that could be, ie the speakers, connector at the back, and the filter inside.QuoteThat's exactly how it turned out to be, by sheer luck. Put the speakers on the bench, and I when I sit on the chair, my ears are just level with the tweeters. How lucky eh ?!QuoteYep. Put them at least 20cm away from the wall.QuoteYep thought of that. A bit of a pain since the cable is all black ! No red stripe anywhere. One of the wires has the insulator squeezed, it's been flattened a bit, if that makes sense. So if you look closely you can see it. Or you can feel it as well.Then I installed my new 2.5m audio cable to connect the CD371 on the bench, to the amp. Then flipped a coin to decide which of the Marantz or the Technics I would try first. The Technics won. They sounded like shit, I mean like there is something seriously wrong with them, broken or something. Sounded like the mid-range speaker was gone. Put my finger on it and indeed it seems dead. The bass and tweeter, I could feel they were vibrating. Had to pump up the volume a lot to get a decent output. Singer voice sounded super weird and faint, like he was speaking from a mile away. Super weird sound. Checked the speaker on the other side of the bench... same problem. Suspicious.Then Tried the Marantz to compare, same problem. Hmmm...Tried using my "regular" CD player, the CDC 486.. and oh miracle, sounds fine now. So there is a problem with the CD371 on the bench, which I would investigate later.So I did my testing with the CDC 486 (TDA 1543) since it was working.The first thing I noticed with the Marantz was that I felt it had too much bass, so shaved it a little using the tone control on the amp.Then at one point I heard the tweeter misbehave for a split second, was having trouble reproducing something. Occurred only once though...was specific to that particular moment of that particular song....Not into classical music so not much into brass instruments. Prefer 70's/'80's pop/rock. Listened to my favorite singers, Daniel Balavoine and Queen, for an hour. Then same songs using the Technics. First thing that striked me with the Technics, in the first seconds, was the lack of "excess" bass the Marantz had, and also felt more comfortable / at ease with the high pitch stuff but.... but.... what annoyed me is that it sounds... "flat". Sorry, I told you I don't possess the terminology !I mean, it sounds technically better, bass and treble, but it sounds... flat. Dull. It's like looking at a picture printed on paper. It represents a nice landscape, but you can't be fooled : you know it's not the real deal, it's nothing compared to being there for real and experiencing it with all your sense and in 3D. Same here. It's like all the bits and pieces that constitute the voice of the singer and the music... are all equal, not one standing out. Like there is no depth to the picture, like an army of soldiers all lined up walking in unison. It's all well organized and pretty, but... it's not "moving", it's boring... no emotions.But then after a while listening to these speakers I convinced myself it was better this way....But it's impossible to compare without the possibility to instantly switch back and forth from one set of speakers to the other, in an eye blink... because honestly after listening to one hour of the Marantz, then an hour later listening to the same songs with the Technics.. brain has long forgotten how it sounded with the Marantz. So, short of having a magical switch to do instant side by side comparison, I did the next best thing : after I had spent an hour listening to the Technics, I ended the show with a song I like particularly and where every improvement in sound reproduction is beneficial and brings more emotion to my brain cells. It makes it easier to spot the good and bad of the two speakers. Once I had played that song on the Technics, I rushed to rewire the Marantz and rushed to the CD player to play again the same song. This way my brain still had some recollection of how it felt to listen to that song on the Technics. Pressed PLAY again.... and wow, yes, my first impression was right. Marantz has its shortcomings explained above, but it also instantly made the voice sound much better to me. Not flat anymore. Felt clearer, sharper, like looking at that landscape in 3D not 2D. All the little elements that constitute the voice and music, seemed like individual characters that lived their own life, the little soldiers were suddenly freed. The voice sounded more "real", like the singer was there in my living room talking to me.So I opted for the Marantz because of that. They are technically not perfect but I don't care about technical perfection, music is about feelings, emotions, and the Marantz extract notably more emotions and thrill out of Daniel and Queen, than the Technics. So... Marantz it will be on the bench. Plus, they are a fair bit smaller than the Technics, which is a plus since bench space is at a premium...Then I wanted to try the CD371 to see if its TDA1541 would make an audible difference. It clearly did (placebo effect ?!...). Had the same effect to me that I felt when going from the Technics to the Marantz. Felt yet again a bit more "real", more "alive".That means I found the problem with the CD 371 crap sound.... turned out not to be the CD player. I eventually realized that this strange weird sound... I had already heard it before somewhere !!! Yes, I had exactly, 100% the same sound pattern when I was fixing my Sony amp headphone jack, if you remember ! Back then Gyro found the problem : bad/missing ground for the return path of the head phone. So, I checked my brand new RCA cable, grabbed my DMM and checked the cable. Did not take long to confirm my suspicion ! Ground problem indeed ! I get 2 ohms resistance between both ends of the inner conductors / center pins of the RCA plugs. On both channels.However when I tested ground, the outer ring/shell.... on the white connectors, a solid open-circuit, and on the red channel, a bit random, either open circuit, or one or two Mohms...So I grabbed my old (much shorter....) cable, and hey presto, problem fixed. So I could try the CD371 now, and found it an improvement over the TDA1543 of my CDC 486.I guess now, the next step is to get a decent amp. My Sony is really a bottom of the barrel piece of crap. I am curious to see if I notice a difference with a decent amp.Midnight here, time to be to bed. Shakal however, being 120° out of phase, is only just about to wake up, he might soon be reading this I think....Anyway, time to fix this display problem on the CD371 so I can button it up and use it as a regular player, for single disc stuff at least. Still enjoy my 6 disc changer when working on the house or on the bench where I don't fancy stopping my work every 45 to 60 minutes to replace a CD.Anyway, quite happy to have a half decent installation. Nice to listen to all my old CD's with decent sound. Just closing my eyes and enjoying the songs a bit loud without distortion. Thrilling....Can't wait to have decent amp, preferably broken and super cheap, of course!Now need to go back to the electronic shop down town, armed with DMM, and ask for a replacement cable... hopefully that will work this time...

author: tautech
author_rank: Super Contributor
timestamp: April 21, 2021, 10:42:55 pm
content: The Technics crossover caps are probably sick.

author: Vince
author_rank: Super Contributor
timestamp: April 22, 2021, 06:25:41 pm
content: "Cross over" caps ?! Lemme Google that... oh, fancy name for the filter board ?!Google served me this page :QuoteA company that specs /designs and make (get made I guess...) their own audio caps.They say that film cpas are best, and that aluminium electrolytics are the worst, and that bipolar electrolytics are even much worse than regular polarized ones. Guess what I have in the Technics ? 100% bipolar electrolytics, mouarf..... it's not just made in spain then.. .it's also designed on the super cheap as well ?! Crap....See pics. 3 caps on the board, all bipolar electrolytics.Brand : " ROE " or " RDE ", not sure how to read their logo...Series : " EKT "Temperature range : 105°CVoltage rating : 63V for all three.Capacitance values : 1,8uF 2,2uF and 10uFMeasured them, they all read spot on. Can't see any bulging a the top. No sign of leakage on the board either, though could be hidden underneath the caps since they are sitting really flush with the board, so would need to desolder them to be sure. However typically if they are dried out, capacitance value goes up, I find...Went back to the electronics ship in town. Guy replaced the faulty audio cable no worries. We tested all 4 wires for continuity before I left, to keep me from having to come back again...Just fitted to it to the lab, works fine, great. I am now much more comfortable to test audio gear, cool....

author: Gyro
author_rank: Super Contributor
timestamp: April 22, 2021, 06:58:43 pm
content: Aged electrolytic crossover capacitors tend to make speakers sound dull rather than bright (note that all capacitors in crossovers are bipolar types, you can't substitute polarised ones). 3-way speakers can have issues with phase and matching in the transitions between drivers in the vocal mid-range range depending on the quality and complexity of their crossovers and crossover frequencies. With small speakers it is often easier to manage the single crossover point and integration of two drivers than three.I suspect that the Technics speakers are more technically 'accurate' and may reveal more about other parts of the chain (the Amp for instance), the drivers may also integrate better at greater listening distance than close up.As I mentioned, I remember Marantz speakers as being warm and inoffensive - not necessarily accurate, just nice to listen to. Regarding the excessive bass output, that may be down to placing them too close to the wall. One very quick and simple experiment that you can carry out is to take your socks off (or even use clean ones!) and stuff one into each of the reflex ports, turning them into resistive ports. That should lower the bass output and extension.It's a shame about the Boston Acoustics ones - I actually saw some pretty positive user comments about them on the web. Maybe you could mount the salvaged drivers in some smaller basic MDF cabinets.

author: tautech
author_rank: Super Contributor
timestamp: April 22, 2021, 08:21:01 pm
content: What Gyro said ^.Bipolar electrolytics have been used in crossovers forever however like any electrolytic they do degrade but as yours tested OK for value they might also need their ESR checked against new ones. Not been down that rabbit hole.....

author: Vince
author_rank: Super Contributor
timestamp: April 22, 2021, 10:44:07 pm
content: Thanks for all the info gentlemen, you never fail to deliver !Planning on getting an ESR tester pretty soon, so when I do I will be able to check those caps. If bad I will see how much it would cost to replace them with quality audio graded caps but I fear they would only be available from some audiophool website that ells them at 10 Euros a piece, so that would be a no-no. I am not a milk cow...Plenty of clean socks I don't use over here, don't know what to do with them, now I know !WIll keep all the Boston parts in one place and label them so I don't forget what they are in the future, when I will stumble pin them...However designing a new cabinet to go with these parts, is an art and science in itself which I obviously don't possess. Today at the electronics shop, while waiting for over an hour, I noticed an old, thick book solely dedicated to cabinet/speaker design... just skimmed the surface and it made my head hurt...Would still potentially like to build my own cabinet / speakers one day, as I like fine wood working, another hobby of mine, and have any kind of particle board in disgust. So would like a cabinet in plain wood using a species that I like the color and look/pattern of. Unfortunately, from old memory, I seem to remember reading that particle board, though disgusting and cheap/crap for the wood enthusiast like me... is actually much better for cabinet design than plain wood, to its better mechanical characteristics. An perfectly even material, with known specs, that's perfectly even/homogeneous material, etc etc... I can understand that, but it sucksCovering it with a fake plastic film imitating the look of wood is just adding insult to injury !So I don't know....One thing is for sure and you seem to agree with it... is that I need to get a better / decent amp ! Again I guess it's gonna have to be (?) something from the late '80s early '90's ? Open to suggestions...Woud like something with lots of stuff in it. A big toroïdal transformer because I love looking at them, and lots of discrete power transistorsWant a quality front panel too. MY Sony amp has really crap looking/feeling plastics, horrible. Ideally would want a machine black painted or anodized thick aluminium sheet as the front panel, and aluminium knobs to suit. It's the complaint I have with the old CD players... nice electronics but crappy bottom of the barrel plastic front panel. It's not impossible to make plastic front panel look with a decent quality factor, look and feel... but it's more effort and money and I guess CD players were not sold for enough money to make such an effort a viable option... I guess they though nobody would want to pay more for a better quality front panel...See you later....

author: tautech
author_rank: Super Contributor
timestamp: April 23, 2021, 12:16:05 am
content: https://uk.farnell.com/webapp/wcs/stores/servlet/Search?catalogId=15001&storeId=10151&langId=44&categoryId=700000100508&st=non%20polarized%20electrolytic&beginIndex=3&showResults=true

author: Gyro
author_rank: Super Contributor
timestamp: April 23, 2021, 11:39:06 am
content: Quote from: Vince on April 22, 2021, 10:44:07 pmYou might look at the details of some of the smaller speakers in the same range - eg.the HD7 (I didn't look extensively) to see if they use the same drivers - only the bass driver is relevant when it comes to the cabinet details. The smaller ones all seem to be sealed enclosure rather than reflex (or ABR), so you wouldn't need to worry about port tuning, just the overall volume and add some fibre filling. You can get iron-on real wood veneers and glue films these days that make finishing a lot easier than it used to be, particularly on small cabinets.Then you can try designing and building some serious speakers...P.S. Yes, even with fine wood working skills, particle board (of one type or another) is better for speakers as it had excellent dimensional stability (you don't want movement and small gaps opening up with humidity changes. It also has higher mass and damping properties. You could always make 'composite' cabinets with MDF lining and real wood exterior though. The best of both worlds.

author: Vince
author_rank: Super Contributor
timestamp: April 23, 2021, 02:12:43 pm
content: Quote from: tautech on April 23, 2021, 12:16:05 amYep but these are generic ones. All the audio boy keeps yelling that the wrong choice of cap makes of breas and amp or speaker, that's why they use fancy expensive "audio grade" caps, some brands specialize i audio caps and make nothing but that...Not knowing where the facts end, and where audiphoolery begins... it's hard to say, being clueless.At the very least, to be safe, I would need to find the exact same brand and model/series of cap. Or at least find the datasheet for them and try to find a suitable replacement.

author: Vince
author_rank: Super Contributor
timestamp: April 23, 2021, 02:26:30 pm
content: Quote from: Gyro on April 23, 2021, 11:39:06 amHmm yes, forgot about that possibility. Not perfect as it would still be particle board inside, but at least from the outide it would be pleasing... or not, if the veneer is the kind that's so thin it come as a rooled sheet. If so, same problems as laminated plastic /false wood : the edges never look right, you can tell it's not plain/solid wood, and with time dirt gets between the edges and it shows more and more.. then the edges start peeling off and breaking into pieces, and the show is over.From memory, in the golden ages of veneer in the 18th century in France, veneer was about 3mm thick (1/8") at the very least. It was more of a thin panel than a malleable thin sheet (which back then they probably would not industrial means of producing anyway, I guess...).So I could make a particle structure covered in proper/thick veneer. This way the joints along the edges would look "propre", would not look fake, and would age well. Not falling apart or splitting apart.QuoteYeah sounds like fun...QuoteGaps along the edges would be I would have thought, easy enough to fix, by depositing a bead of sealant inside the cabinet, all along the edges ?!Picture looks "mionstruous"... 1kW speaker otr something ?!Is that one you made yourself, it's your home ?

author: shakalnokturn
author_rank: Super Contributor
timestamp: April 23, 2021, 03:25:18 pm
content: I'd bet Gyro's speaker is lowish power with high efficiency, wasn't able to identify the woofer though.The fuss about the crossover caps is I think mainly a question of Q factor and ESR. Of course electrolytics age more than others over time.The Russian rectangular can paper-oil capacitors have a good reputation for crossover use in the audio world.

author: Vince
author_rank: Super Contributor
timestamp: April 23, 2021, 04:21:33 pm
content: Wow, so now I need to learn Russian to be able to buy caps for my speakers... this is quickly getting out of hand !!

author: Gyro
author_rank: Super Contributor
timestamp: April 23, 2021, 04:58:19 pm
content: Quote from: Vince on April 23, 2021, 02:26:30 pmNo , veneer isn't what it used to be, unless you cut your own of course - not impossible for small cabinets I suppose, although the composite idea would probably be better for mitred joints (my veneer runs so that there is no visible joint where you would expect to see an exposed mitre). I did at least use a proper glue method rather than film or Iron-on.QuoteTrue, real wood still doesn't have the same damping properties though, the long grain fibres make it resonant along the length, you could use extensive internal bracing though. Ply is another material that is used on some high quality speakers, that blends good rigidity and damping.QuoteYes it is - and I made another one just like it.As shakalnokturn says, they are very efficient and very easy to drive. It's a fallacy that big speakers mean massive speakers (unless you're talking stadium PA stacks or something). I think the drivers are rated at 50W, but you'd never go there. Doing things efficiently means fewer compromises. In comparison, I think I read that the Boston M9s were rated at 130W (all RMS). To get the same output (volume and frequency response) from a small speaker means more losses, ultimately turning into heat, it's just physics.Quote from: shakalnokturn on April 23, 2021, 03:25:18 pmThe drivers are Tannoy 12" HPD dual concentrics (horn tweeter diaphragm in the rear, with the centre magnetic pole piece and cone forming the horn). I bought them for about £25 many years ago, needing new surrounds. Similar driver pairs go for around £1000 on ebay these days, out of my budget. I built the cabinets as tapered transmission lines rather than the traditional Tannoy bass reflex. I would have liked to go for one of their horn designs, but there's no way they would have fitted sensibly in the room! These are about as compact as you can sensibly go.I built the Aluminium ribbon upper tweeters from scratch. I used Samarium Cobalt magnets from abigold server HDD (much easier with Neodymium these days). The ribbon came from Polystyrene capacitors, turned to length (ribbon width) in a lathe and then carefully unwrapped and corrugated between gear wheels.QuoteAgreed, my crossovers are full of them! the round ones too. Excellent capacitors.Sorry, I've taken the thread as far OT as you do Vince!

author: Vince
author_rank: Super Contributor
timestamp: April 23, 2021, 05:12:12 pm
content: Quote from: Gyro on April 23, 2021, 04:58:19 pmWell, no need to apologize, OT is where you discover people's talents and interesting unexpected stuff.I now know you are very deep into audio, much more than I could ever imagine. So I know who to turn to for any audio stuff...For local needs I have Shakal, he lives not too far away from me, IIRC... well, not at the other end of France anyway.Maybe I should pay him a visit, bring my CD371 and CD's, so I can listen to them on some of his speakers, see how good it can sound. Then try my CDs on his modded old Philips to compare with my stock one.... I don't know.You and Shakal should exchange e-mail addresses and marry each other. You seem to be on the same wavelength. Audio wavelength of course... You would give birth to lots baby speakers and baby CD players and amps. I would pick some of them and grow them in my house.Yeah sounds like a cool idea....

author: Gyro
author_rank: Super Contributor
timestamp: April 23, 2021, 05:55:47 pm
content: Quote from: Vince on April 23, 2021, 04:21:33 pmThe stocks of former Soviet era military warehouse stuff available on ebay, from places like Ukraine, can be a treasure house of high spec parts. Obviously you need to be selective, but hermetically sealed components and things like valves (tubes) don't really care about spending decades in cold warehouses as long as they are kept dry. Some parts have long since become completely unobtainable new here, for instance large value polystyrene and Silver-Mica capacitors.The output valves for my amplifier cost about£4£6 each, compared to £100 or more for the more well known audiophile (not even audiophool) types, much more rugged too. Of course, you need to design these things in, they're not just pin compatible (actually, some of the lower power ones are). Unfortunately, sellers have become more knowledgeable about what they have so prices have slowly climbed over the years, but there are still serious bargains, and it means that they are also able to include more information.Haha, it sounds as if you do need Shakal near you, just to select the treasures from the trash in your ongoing acquisitions.He's clearly very knowledgeable when it comes to audio!

author: Vince
author_rank: Super Contributor
timestamp: May 02, 2021, 07:37:38 pm
content: Hmmm... sometimes you get lucky : went through my pile of CD players, to see what could be sold, what was working.... last week I put that Sony CDP-C305 5 disc changer for sale, at 40 Euros, just because I am daring. Market here is completely flooded with old CD players, so I expected never to sell it, or to sell it in 6 months once I had dropped the price progressively down to 15 euros max....But, what do you know ? Less than a week after advertising it, I got a guy interested last night, saying he would come in person today ! And he DID show up ! Picked the player and did not even try to bargain me !So, got my 40 Euros, in just a few days, truly unbelievable.What's more : I of course let him play some CD's to see for himself that it was working fine. Said the sound was really nice on my Marantz speakers.... and he instantly spotted my pair of Technics speakers I had put in the background along the wall. Asked immediately if they were for sale !Asked if he could listen to them. OK why not. I wired them in place of the Marantz. Played Bohemian Rhapsody as it's a nice song to test speakers, we agreed on that. Said they sounded nice, even if the Marantz were better.Insisted again that he would be interested if I would sell them to him... said OK will do some research to see what would be a fair price, and get back to him soon.Technics SB-CS7 they are. Turns out there is quite a bit of info on these things, and a few for sale, so I was able to figure out what a decent price would be. More than I expected. I told the guy 80 Euros for the pair. Some sell them well above 100, other at 60... but he could listen to them and hear for himself that they were working fine. Buying them at 60 online then having to add 30 more Euros to package them properly and get them shipped, 90 Euros in all... and then you have absolutely no guarantee whatsoever that they will be in good shape/sound OK when you try them ! So 80 Euros for a pair that's local to him, no shipping, and he knows for a fact that they work fine... sounds a fair price to me. Waiting to hear back from him.Also, he said he has a couple CD players that don't work, said he could not find anybody to fix them, so asked me if I would accept to have a look at them !Hey, business is coming in fast !So, 40 Euros in just a few days for this player I paid only 5 Euros shipped for, and that I fixed in 30 minutes without even having to buy any part... excellent deal.Guy was well impressed with my stack of 20 players and my 20 tube Tek scopes.Sadly not many of my players are economically repairable. The few that do work are actually those that I want to keep, pfff...I have a Philips CD824 (from 1990) which I like the design of. Seems to sell for a lot of money on Ebay, 85 at the cheapest, a couple at 120/125 Euros, and one at 280 Euros on offer. Mine works fine, but the drawer is kaput, its gear shattered into pieces like glass. Think I might have found replacement kit (gear+ belt) on Ebay/China for under 5 Euros shipped. Of course I won't know for sure if the gear fits, until I have received it. In 6 months maybe... china stuff is cheap but always takes a month minimum to arrive, it's annoying...If it works, then with a 5 Euros fix, I am good (paid 30 Euros for the player IIRC). If I can sell it for 100 Euros or so, that will be some easy money.I will miss it as I like its design and keypad to get direct access to tracks, a neat feature as I find it painful doing long jumps on a CD. Have a CD I like with 19 tracks on it. Getting to track 19 directly is a time consuming and frustrating exercise on a normal player, as the player "stops" at every track along the way. Keypad is a revolution...I don't know why they are so expensive... OK they have a swing arm, but crappy shitty looking CDM4/19. Nowhere near as sexy as my white CDM4/11DAC is.. not a TDA, but an "SAA" something...Anyway, was nice meeting that guy, good quick business. Now here is hoping he will buy the Technics speakers ( = a quick buck and less clutter in the lab/living room) and pay me to fix his 2 broken CD players.

author: Vince
author_rank: Super Contributor
timestamp: May 02, 2021, 07:38:53 pm
content: No haven't forgotten about the CD371... going to order the shift register chip and some proto boards, want to experiment real soon with that...

author: Gyro
author_rank: Super Contributor
timestamp: May 02, 2021, 08:04:39 pm
content: We're going to start charging you for advice!It sounds as if you managed a good deal there.The Philips CD824 has an SAA7321 Bitstream (delta sigma) DAC, you might want to compare and contrast with the TDA1541A models. The gear wheel problem is common on Philips / Marantz players of a certain age - Philips used a lubricant that was incompatible with the plastic of the gear wheel, making it become brittle. I'm not sure when this became a problem, I've never experienced it on any of my players. I use a plastic grease for lubrication (Electrolube SPG*). The problem has led to a thriving market in new replacement gears though - it is getting easier to find them closer to home.*RS and Farnell sell it, unfortunately TME don't.

author: Vince
author_rank: Super Contributor
timestamp: May 02, 2021, 08:37:16 pm
content: [ Fixed 1,001 typos in previous message.... ]Quote from: Gyro on May 02, 2021, 08:04:39 pmOK, will do as soon as I get its drawer fixed...QuoteIndeed, countless ads on Ebay China for replacement gears for the old Philips... but not so much luck for Sony players or more recent Philips Players.Other than my CD824, have 4 Sony players and a recent Philips 5 disc changer, all in need of a gear here or there. None for saleQuoteAh, thanks for the explanation, explains indeed why there is such a market for these players nowadays...QuoteWow, lucky you ! Have only 20 players yet no less than 6 of them have a problem with one gear or another !QuoteThanks for the ref, was going to ask. Need to get some of that stuff now that I work on old consumer stuff....Too bad TME don't have it, was gonna order from them for the shift register as way cheaper there....

author: Vince
author_rank: Super Contributor
timestamp: May 03, 2021, 04:32:20 pm
content: What do you know ! I received the replacement gear today ! Took only 2 weeks to arrive, faster than in PRE-covid times, go figure !The Philips CD824 now works !Drawer makes a horrible noise though... not sure if it's due to crappy Chinese tolerances, or the total lack of grease on that gear since it's brand new, or the fact that everywhere I look in the drawer mechanism, all I can see is dark brown, bone dry, rock hard grease... need to clean all that, and empty a bucket of fresh plastic grease everywhere. Gonna order some...Other contributing factor I suspect, is the mechanical design itself ?! I mean, the gear is very wobbly. It simply snaps into a recess, it's very loose to begin with. Very cheap and shitty design if you ask me !In contrast, in my Technics players which feature the same CDM4/19 and drawer mechanism, it's much better designed I find : the gear is the same, but mounted in a different way : does not snap into plastic recesses. Instead, like you would a gear in normal times.. it's mounted onto a beefy metallic shaft. Gear is perfectly guided, zero wobble, zero play... just spins smoothly, perfect.Another cheap looking thing on CD824, I find, is the shiny black finish of the drawer bezel. Makes it look very cheap/plasticky, and also looks out of place compared to the rest of the front panel that's flat black (which is what I like personally. Hate shiny finishes). They also placed the "OPEN" button on the drawer bezel itself ! Looks weird, and ergonomics is poor, especially when you want to CLOSE the bloody drawer. There is no" CLOSE " button... Pushing the "OPEN" button again does nothing. So either you have to brute force the drawer and push on it to force it to close, or you pressed the "PLAY" button, which again ergonomics wise is poor : what if I just want to load the CD and its TOC, but not start playing right away ? Can't do that.So really, to me at least, it appears every aspect of the drawer thing, is poorly designed and implemented in this player... it's my biggest gripe with this player.OK, so now it works, so let's test it against a TDA1541. The CD371 has its guts all over the shop right now, so instead I pulled the Toshiba.Stacked the Toshiba on top of the CD824. Powered both players with their own power cable. This way I can swap from one player to the other, as fast as humanly possible : play a song, stop player, retrieve CD, open drawer of next player, press PLAY, and while it's loading the song, hurry to switch the audio cable at the back of the players. It's the best I could figure out to minimize waiting time between hearings. To make it faster/better, I could buy another audio cable so that both players are wired at the same time, and I have only to press a button on the amp to instantly switch the source. Would also need to make a copy of the test CD so that I can have the same audio CD in both players at the same time. This way I won't have to swap discs. I can just preselect the song on both players, press PAUSE on the second player. Then once I am finished listening to a song on the first player, I can just press PLAY on the second player, press the corresponding source button/selector switch on the amp, and that's it ! This way, I guess I can have a very tiny dead time between hearings. Like a coupe seconds. Would need to rip a few CD's in a lossless format like FLAC, I guess ? Of course I have already my entire collection of CD's on my computer, but back when I ripped them all, was like 20 years ago IIRC. Back then my computer didn't have quite enough storage capacity to contemplate FLAC, so instead I compressed using OGG, because 20 years ago they said OGG was better than MP3, IIRC...Just checked, I ripped them back in the day in OGG 160kbps. A 4 minutes track weighs about 5MB.Anyway. So I first listened to the CD824 then the Toshiba.Again, I am not qualified to talk about audio, so just my personal feelings with my personal unofficial vocabulary, sorry it that makes no sense to anybody.We are close to audiophool territory so arm your BS detector as wellOK now that all due precautions have been taken... here is what I thought :At first, thought it sounded super nice, was surprised. then after a few minutes I analyzed my feelings and figured it felt like it was a bit hollow, and like it was applying some artificial digital special effects to the sound, that made it sound attractive at first, but in retrospect felt unnatural. Felt like a Hollywood movie : lots of action, special effects by the pallet, you get attracted to it like a sweet/candy, and enjoy it while the movie lasts but you know it's just cheap emotions, you know it's not real, it's all fake and overdone.Then I rushed as fast as I could to swap the CD into the Toshiba. Sound felt less spectacular, but more natural, the music and the singer voice sound more real, and more present, like they were in your living room playing and singing live. Provided more emotions, real ones, not fake.Played a few of my favorite tracks from Daniel Balavoine : " Tous les cris les SOS" , " Le blues est blanc " , "Un enfant assis attend la pluie", and the Toshiba gives a shiver down the spine and brings a tear to the eye. I know, I am too soft, I know...At the end of the day I guess it doesn't make much sense to pretend that one DAC is "better" or "worse" than another... it just depends on what type of music you like to listen to, and your personal preferences.. it's like for girls or cars...Searched ebay for decent proto boards locally so I can get fast shipping compared to China. Found that ad :https://www.ebay.fr/itm/164167899811?hash=item26392b5aa3:g:N6QAAOSwFpNc9Mkc2,50 Euros for a set of 4 FR4 board of varied dimensions. The largest one looks like it would be just large enough to accommodate the DIP version of the shift register along one of the long edges, taking about one half of the board, and the other half would be enough space I think to fit the 7 segment LED displays.The other boards I can reuse for whatever other project later, not a waste.Shipping is about 4.50, twice as much as the board, but well that's the price to pay for local/fast shipping...Might buy some from China as well so that I can have a larger stock for cheap. China also gives more choices, I can get larger boards there:https://www.ebay.fr/itm/183544234631

author: Gyro
author_rank: Super Contributor
timestamp: May 03, 2021, 05:45:03 pm
content: Congratulations, you have a good ear (and not in an audiophool way). That's a very good summary of the difference between the TDA1541A and later Bitstream players. The Bitstream ones are very 'in your face' - immediately impressive, but lacking in subtly. It's abitlike 'Shop mode' on TVs, it makes the colour more vivid so that the TV stands out in the store, but you would be uncomfortable using this setting normally. Given that you are listening to the Toshiiba in it's original stock mode, with no improvements, your experience is hopeful.One problem with the Bitstream DACs is that Philips integrated everything on-chip, including the audio opamps, which are not of the greatest quality as it is a mostly digital chip fab process, and you can't get around them. All sigma delta DACs need noise shaping etc to work though. The TDA1541A, by contrast gives you the direct output of the bit current switches, making it much more possible to optimise the analogue filtering and output design, as you will see in Arcam players for instance (compared to the standard Philips reference design) - it would be nice to see the actual Toshiba schematic.Your photo shows what I mentioned about the mechanics of the later players - that web structure of plastic, holding the drawer motor, slotted-in gear etc. This makes it impossible to keep the transport and loading mechanism as single unit, they are completely tied into the case moulding. Yes, noisier drawers are normal.The display is nice though - it makes the player look more expensive. The differentiation on these players is all down to styling, display and number of buttons with maybe the s-pdif output populated on some models.Hopefully you can see the value of the CD371 as a basis for a project (whilst enjoying the Toshiba).P.S. Did you ever post a picture of the Toshiba PCB? I can't remember.

author: Vince
author_rank: Super Contributor
timestamp: May 03, 2021, 07:33:45 pm
content: Quote from: Gyro on May 03, 2021, 05:45:03 pmWow, I am stunned ! I can't believe that I managed to convey something worthwhile with my word salad, especially given my total ignorance of the appropriate terminology, not to mention the language barrier of course, being a Frog. Either I got very lucky, or YOU have a talent for making sense of my salad. You must a very selective / High Q filter taht's able to discern a faint signal lost in an ocean of noise. Gyro is one hell of a fine piece of lab equipment !QuoteSounds better and much more concise when it's you telling it !Good analogy with the TV !QuoteWow, very interesting indeed ! Thanks for that. Cold technical/engineering fact, that hold water, that actually make sense...the anti-thesis of audiophoolery that's religious-like, faith-based tales that spread like a virus and can never be killed.Nice to see that even though enjoying audio is very much an irrational / subjective feeling, there are none the less some actual technical reasons that can put some sense in that picture, and I enjoy every bit of such information, keep it coming !!!QuoteAt first I didn't want to spend the 5 bucks websites wanted for the service manual, both out of principles (in 2021, paying for a 30 year old schematic... really ?! Who does that ! ), and also because it would eat a good chunck of any profit margin I could hope for, when reselling the player. But that was back when I got it. Now is different... I know I will keep that player, it's my baby.. so, spending 5 mere Euros to get to learn its guts in detail, sounds like cheap and worthwhile. So I think I will cough the 5 Euros....QuoteYep, all show and no go as they say !Almost got me ! ... but looking at the thing in detail and in an objective manner... freed me. Now I am "ready" to sell it, and hopefully quite a good profit in the process, seeing for how cheap I got it and how much it seems to fetch on Ebay !QuoteYes. The CD371 is indeed a good candidate. I mean all the mods are clearly documented for it, by Shakal at least how did it on his. Plus, the poor thing is already going to be butchered in order to work around the unrepairable stock LED display module... so I would rather not butcher both players !Prefer to keep the Toshiba stock and fiddle with the CD371. This way I can also use the Toshiba as reference when assessing mods I do to the CD371. I will always have a stock 1541A to come back to when needed, when I want to.[quote}P.S. Did you ever post a picture of the Toshiba PCB? I can't remember.Yep I did, a while back. You looked at it and figured it must be based on CD473 board, if just based on the odd placement of the DAC, far away from the final op-amps. You also said that it was not, though, a C473 board since one of the big chips was unpopulated on the Toshiba : the one in the very bottom right corner of the PCB. Said it was an EEPROM used to store data to implement the "FTS3/ favorite tracks feature, which the CD473 has, but the Toshiba doesn't have.I just looked at the board view of schematics in the CD473 manual, indeed it appears to confirm all that you said. Same layout ads the CD473 with just the EEPROM unpopulated.Would still buy the Toshiba manual anyway, to be 100% sure of every details of the schematic, and get the Toshiba specific parts, like the front panel stuff.Attaching again the Toshiba main board picture, to keep you from having to rewind this thread....Went to order the shift register on TME.... TOO LATE, now says out of stock, and adding to boot "WARNING : HARD TO GET !!! "Should have hurried. So now back to Farnell, where it's much more expensive.. that's life. Well at least I get to buy the plastic grease, so it's not all bad. That stuff must be made of solid platinum : 20 Euros for a 30cc syringe, REALLY ?!In all fairness, given how sparingly the stuff is meant to be used, even that 30cc syringe will probably outlive me !

author: Gyro
author_rank: Super Contributor
timestamp: May 03, 2021, 07:45:29 pm
content: Thanks for the compliments!Ah yes, I remember now - the depopulated 473, stock Philips PCB. In that case there's no need to spend the 5 bucks, we know what the schematic is. We also know that Toshiba didn't do anything special to achieve the sound - that's a good thing!P.S. Shame about TME, at least buying it and the grease (and a few other bits?) might get you past the free shipping threshold, which should offset the difference in cost. Yes 30cc goes a very long way!P.P.S. The front panel will be using the standard CD473 I2C interface. Philips might have done a custom micro for their keys / display but very possibly not. It's easy the reverse engineer the buttons anyway.P.P.P.S () I just noticed one small difference in your photo - Toshiba used a crystal for the microcontroller clock rather than a ceramic resonator (stock Philips). Potentially one less source of jitter superimposed on the GND / +5V supply rail relative to the transport clock? I don't know, but it cost them a little extra to do that, interesting.

author: Vince
author_rank: Super Contributor
timestamp: May 03, 2021, 08:57:04 pm
content: Quote from: Gyro on May 03, 2021, 07:45:29 pmYep I do need a few other bits and bob for a tiny design project for a friend, long overdue.However it shouldn't be needed to get passed the threshold at all. Haven't ordered anything from Farnell in a very long while (2+ years ?....) due to my house move fiasco, but IIRC threshold to get free shipping is only 15 Euros (before tax I think). In other words, ordering the grease ALONE is enough to get free shipping !Yes, you are right, free shipping at Farnell means I get to save 8 Euros over TME, since their shipping fee never goes away.So that more than offsets the silly price difference on the register chip. So it's not that bad ordering from Farnell in the end, I guess.Will complete my order tomorrow. For now.....

author: Vince
author_rank: Super Contributor
timestamp: May 04, 2021, 07:13:45 pm
content: OK, some display action !Since that guy on that website implied that he managed to salvage the original display, I gave it a try. I assumed it must be surface mounted, so I applied some heat at the back of the PCB with the hot air station, see what that would do. Nothing, won't come off.Turns out it's not soldered to the PCB ! The "display" that we see is in fact a mere bit of plastic, held by 3 pegs that are heat welded at the back of the PCB. I snapped them off with a sharp blade, and the "display" came off instantly, no drama.The LEDs are not part of the plastic housing.. they are completely separate, soldered directly to the PCB, as individual LEDs. The LEDs themselves aren't even packaged as such. They are just bare dies bonded directly to the gold plated tracks on the PCB. I took a macro shot of the dies, you can clearly see the tiny fragile bonding "wires" that connect the anode of the die to the golden trace on the PCB, the common anode trace. Like it were an integrated circuit... looks so cool, I so wish I could afford a decent microscope with a camera, to take much better shots of this. No, no USB "microscope" for me, want an actual stereo microscope with a port for a camera.I tested all the LEDs with my DMM... some of them won't work. So can't reuse it. Would not have been fun anyway, trying to reuse the existing PCB with its routing... So next best thing I guess is make my own PCB and solder tiny SMD LEDs. Well, that's were I would really need a microscope then !Aligning so many so tiny packages would not be possible with a naked eye. Not with MY eyes at any rate, don't know about yours...Problem : a bare die can just about fit inside the "slots" in the plastic housing.. but a PACKAGED LED hmmm... not sure there exists an SMD LED with a package so tiny that it would fit in the existing slots....I tried to eye ball the dimensions of the slots with my calipers. I would say they measure about 3x1mm. So I would need a package that's smaller than that, so I can be sure it will fit, even if I don't get the alignment perfect, which of course I won't.Failing all that, I guess I can try to find a replacement display, like people did on that other website. Sadly the shape of the segments of the display they came up with, is different, and I don't like it. Will see what I can find on Farnell website.... if I can't find anything, never mind. Would still complete my order and use displays I have in stock, even though they are 4 times larger. Still good enough to go past the proof of concept stage.... if successful then I can worry about finding an appropriate display.Anyway... making some progress at least....

author: Gyro
author_rank: Super Contributor
timestamp: May 04, 2021, 07:29:27 pm
content: Ah yes, I maybe should have pointed out that the LEDs would by chip-on-board with bond wires. A lot of LED displays are (/were) done the same way. If all the bond wires are visibly intact, then it may be that the output pins of the chip on the back are shorting them. The actual diode test voltage reading on the DMM will tell you.I think I mentioned before that there are replacement display PCBs on ebay that re-use the existing plastic part, so there ought to be enough space for modern SMD LEDs. Here's an example (see the description and second picture)...https://www.ebay.co.uk/itm/294024117929

author: Vince
author_rank: Super Contributor
timestamp: May 04, 2021, 07:54:27 pm
content: Thanks for the link ! Exactly what I need then !SMD LEDs already soldered perfectly aligned, PCB already done, cane re-use my existing housing for a perfectly OEM look... 27.50 Euros + 10 Euros shipping, 37.50 Euros for a perfect solution with zero R&D and production cost, turn key solution... it' s a no brainer.Still, for the fun of it, I would still like to cobble quick and dirty proof of concept with a DIP package and proto board and whatever LED display I have on hand... then when I am done with the fun part, I will just order that PCB on Ebay to get the bloody player fixed quickly and properly, and move on to the gazillion other things that I have to do.

author: tautech
author_rank: Super Contributor
timestamp: May 04, 2021, 08:08:09 pm
content: 16x 0603 LED's and possibly a little work with a Dremel might save you ~30 Euro.

author: Gyro
author_rank: Super Contributor
timestamp: May 04, 2021, 08:12:27 pm
content: Quote from: Vince on May 04, 2021, 07:54:27 pmAh ok, I was thinking that you would choke at the price (still half the price of a potentially unreliable NOS display though).You might want to use this other link instead as it specifically states MM4202A (same seller)....https://www.ebay.co.uk/itm/294024117929P.S. The proof of concept display will be good if you decide on the 'project' approach in a more substantial cabinet. You could do things like bigger digits for the Track vs Index digits (Minutes / seconds in time mode). Also having a choice of display colour.I notice that the ebay display has the option of Red LEDs too.

author: Gyro
author_rank: Super Contributor
timestamp: May 04, 2021, 08:17:15 pm
content: Quote from: tautech on May 04, 2021, 08:08:09 pmYes, that is certainly an alternative solution. Earlier in the thread we were discussing the MM5450 IC which provides the logic functionality (the MM4202A display is intelligent) allowing the choice of any common anode 7 segment displays. The cost of the IC needs to be factored in.EDIT: I'm not sure whether anyone has ever figured out whether it is the COB driver IC or the LED dies themselves that fail in these old displays (presumably the former in this case as it didn't lightanysegments).

author: Vince
author_rank: Super Contributor
timestamp: May 04, 2021, 08:45:26 pm
content: Quote from: tautech on May 04, 2021, 08:08:09 pmTHe problme is the chip not the LEDs... the bonds inside the big black blob are intermittent, I can't fix that. Replacing the few dead LED's I (probably) fuckd up when handling the module after I had removed the plastic housing, will not fix the chip...Need a new PCB with a replacement chip. That means R&D costs and time, messing with tiny LEDs to ling them up, don't have a microscope etc. Once you factor everything in, 37.50 Euros for a turnkey perfect solution, is fucking CHEAP !!!There is no way I could come up with the same product for less money, and all the time spent doing it is priceless too, I have fucking a millions other things to do !No no... Nooooooo 37.5 Euros is a life saver ! Plus, it's not ending up in some chinese ebay seller, instead it goes to some Philips CD player enthusiasts in the Netherlands who took the time to do all the work and bothers selling it on ebay to help others. I am more than happy supporting that kind of people.I have plenty of other custom design projects to spend my time and money on, don't worry !This module just isn't one of them...

author: Vince
author_rank: Super Contributor
timestamp: May 04, 2021, 09:01:12 pm
content: Quote from: Gyro on May 04, 2021, 08:12:27 pmIt's a total no brainer, one would have to be a fool to think he can come up with the same product for much cheaper, for a one off, unless he does not count his time or much anything really. I am old enough now that I am starting to value TIME much more than I did 20 years ago, for sure...QuoteExact same link / ad that you posted earlier !You got it right the first timeQuoteNope I don't fancy spending time and money doing my own cabinet, which would look amateur and junk at best, I guess.... however I sure am disappointed that CD players manufacturers, no matter how high-end, all had cheap crap chassis and front panels. None of the billions of CD players that hav come to exist meet my expectations, how ever basic they are. The quality factor of the cabinet hardly ever matched the quality of the audio. Cabinet was always an afterthought it seems. EIther that, or doing a decent cabinet would cost so much in material and tooling that the final price of the product would be staggering even for a high-end player, and nobody would have bought them...Anyway, even though I won't be making a custom cabinet, I still want some quick fun cobbling together a DIP package shift register on a proto board. Not costing much, not going to take much time at all.. just some quick cheap fun, then move on to the next problem !Only custom things I seriously envisage as I said earlier, would be customs speakers with a home made / custom wooden cabinet, so I can have speakers I actually enjoy looking at as well as listen to.

author: shakalnokturn
author_rank: Super Contributor
timestamp: May 05, 2021, 06:44:05 am
content: You should start looking for a Studer / Revox CD player.You're not going to like the price though...

author: Gyro
author_rank: Super Contributor
timestamp: May 05, 2021, 04:48:45 pm
content: Quote from: shakalnokturn on May 05, 2021, 06:44:05 amAren't we all!Edit: Actually, looking at the Studer A727 service manual, the post-TDA1541 I/V and analogue filter circuit (fixed level output) is pretty much identical to the Philips CD371! Likewise the Revox B226. The devil is all in the detail - PSU rails, grounding etc.

author: Vince
author_rank: Super Contributor
timestamp: May 05, 2021, 05:44:28 pm
content: Hmmmm... I don't even want to check prices for these things, I have no intention to spend money I don't even have, for a nice cabinet, I am happy neough with my plasticky Radiola and Toshiba....OK, trying to order from Farnell.... looks like the bastards have changed their policy ! No free shipping anymore above 15 Euros... there is now no minimum order, but a fixed 10,68 Euros "fee" that applies no matter what.TME has no fee but a fla shipping charge of 9,48 Euros...So, all in all... TME and Farnell now have similar policies, and I will be lose 10 Euros no matter where I order from and no matter how large the order is. Sucks !So I checked, just for fun, a local / small electronics shop, in the next big town 40 miles away. They have a website I order there from time to time. I am stunned : they DO carry this bloody MM5450 shift register !!!http://www.e44.com/composants/composants-actifs/circuits-integres/circuits-analogiques-mixtes/drivers-led/nmos-ic-led-display-driver-dip40-MM5450N.htmlOf course more expensive than Farnell, but not by all that much : 9,50 Euros vs 7,40 for Farnell. Shipping is only 3,50 Euros, not 10,68 !!! And free pickup if you can get to their shop. It's 40 miles away does not make economical sense in my case.So... fuck Farnell !!!!Too bad for the Electrolube SPG, will have to find some elsewhere, in smaller and cheaper quantities...or another brand. Looks like Molykote makes some plastic grease too. Many flavours at that, hard to chose :https://www.lubricantspecialty.com/categories/application/plastic-lubrication

author: Gyro
author_rank: Super Contributor
timestamp: May 05, 2021, 06:39:35 pm
content: That's a shame, I think many of the suppliers are sneaking in delivery charge changes again. Gone are the days when RS used to have free delivery on all orders for instance.I'm sure a Molykote plastic grease would be fine too, I think I've seen it specified for some linear pickup systems. The only real requirements are to stick well to slippery plastics, not migrate, and of course, not have chemicals that degrade sensitive plastics (that one can take about 20 years to find out!).

author: Vince
author_rank: Super Contributor
timestamp: May 07, 2021, 07:30:43 pm
content: OK I am losing it... when I read Farnell's terms and conditions, I understood you got the 10,68 Euros fee no matter what. Now, I put all the bits I wanted in the shopping cart just to see, and when it states clearly at the top of the shopping cart that the 10,68 Euros fee goes away for orders above 30 Euros (before tax, so 36 Euros or so incl VAT). Indeed, tehy did not charge me anything..... so I ended up ordering from them in the end, so the Electrolube SPG plastic grease will be here soon, yeah... can't wait to taste the stuff ! Given how expensive it is, it HAS to taste delicious, HAS TO !I am now officially 54,14 Euros poorer. 40% of that just for the grease, ahem....Well at least I have a life long supply of the stuff, handy, and a large 100x160 proto board that can alwyas be reused for lots of things, and of course I bought all the bits I needed for the little design project I am doing for a friend. So not so bad in the end...Wanted to buy some 63/37 0.8mm solder, but looks like it's defunct. 60/40 rules the market. Even then, cost bloody 25 Euros for a small 100gram spool ! This has to be a joke... so did not buy any. Maybe COVID is an alround excuse across the vendors to doubles prices.... will wait for COVID to go away and the economy to recover, before checking prices again...Can't wait to receive my order and to wire up that shift register see what I can come up with !They did warn me that shipping times were affected by COVID, but I doubt it would delay my order by more than a couple days over normal. We shall see...Anyway, stay tuned, some action soon !

author: Vince
author_rank: Super Contributor
timestamp: May 09, 2021, 04:34:45 pm
content: Hmmm... that's a weird one. Maybe you people can enlighten me...I just managed to fix another player in the stack. Have a couple twin brothers : a Sony CDP-C335 and a C365. Both have a damaged plastic gear, but not the same one. So I can make one good player out of the two. Which one gets to live and which one gets to be the donor, was obvious : the 365 was damaged during transport, big crack in the bottom left corner of the front panel. Also, the Sony logo at the front is missing, somehow. Plus, it's lesser spec than the 335 : 335 has head phone jack at the front, with volume control. 365 has no jack. So, I fixed the 335. Works like a charm, been playing music for a couple hours at least now, flawlessly. However of course I wanted to check the amplitude of the eye pattern to see where it's at.My problem is that when I connect the scope to the RF output to check the eye... the player somehow all of a sudden fails to detect the discs ! If I disconnect the scope, start playing music, then while it's playing I connect the probe to the scope... a couple seconds later, the player can't read the disc anymore (time counter stops) and the player stops the disc !Oh dear...I thought maybe a ground issue, but precisely to avoid that, I powered the CD player from my isolation transformer. Plus, I shouldn't even need to do that, since the player has no ground connection, and linear power supply so the transformer already isolates the player.So I thought, maybe the RF signal is very weak, and the scope probe in x1 mode is too much of a load, weakens the signal just enough to make the signal too small for the player to maintain operation.Fair enough.. at a time base of 500ns I should not be using x1 anyway, I guess... so I switched to x10 to increase the impedance of the probe.... still no luck, no change.The RF is checked directly at the output of the pickup, as per the manual, rather than at the output of the Rf amplifier.. probably because looking at the schematic, teh RF amplifier is not accessible, looks to be embedded inside the main decoder chip. Still, even then, the manual says that I should be getting a strong signal, 1,2V or something... so there is some kind of amplification going on in the pickup itself ?!...Anyway, I don't understand what's going on... I fear I might have to sell this player without being able to know the amplitude of the eye, and that makes me feel uncomfortable.... don't want the player to "magically" stop working once the buyer gets it. Well, assuming someone wants to buy it of course !Any similar experience or ideas on the subject ?!....

author: Gyro
author_rank: Super Contributor
timestamp: May 09, 2021, 05:28:26 pm
content: I certainly wouldn't expect it to work with the probe on X1, too much loading.With X10 it really depends how much loading the signal will take - It could be that the 10M input resistance is upsetting the DC bias point of the signal for instance. It should work with the scope set as specified in the service manual though.Sorry, Sonys aren't my area!

author: Vince
author_rank: Super Contributor
timestamp: May 09, 2021, 05:51:10 pm
content: Yeah my problem with teh loading hypothesis, is that well, the manual tells you to scope on that particular test point, so should not be any problem.They don't even tell you to use x10. They even states to set the scope attenuator to 200mV/DIV, which implies the probe is set to x1 not x10...I am not CD player racistIf I were, I would never have bought a little Radiola and Toshiba, and would have missed on the best stuff !Maybe Shakal will have an idea...

author: shakalnokturn
author_rank: Super Contributor
timestamp: May 09, 2021, 07:34:23 pm
content: I've run into the problem before not being able to scope the eye pattern at x1 and having to switch to x10 to not disturb the player.Probe and scope input capacitances are worth considering as well as any close source of interference that may be injected by hooking the probe.What amplitudes if any were you able to measure probing at x1 and x10?What model is the pickup?How picky is the player on dirty/scratched CD-R discs?

author: Vince
author_rank: Super Contributor
timestamp: May 09, 2021, 08:15:32 pm
content: Quote from: shakalnokturn on May 09, 2021, 07:34:23 pmHmmm.... if it's that sensitive a thing, then I am thinking the problem might come from the fact that it's not possible to scope the RF directly (unless I put the scope vertically on its side.. doubt it would operate happily this way....) .. so I did what I always do : I solder two long wires to the test points (RF and ground), so that I can put the player in its normal position, and have the wire coming out on the sides.. then I can hook the probe to the end of these wires. Wires are quite long as a consequence... I don't know, 40 or 50cm maybe.I could try using some coax cable instead of mod wires, or solder tiny wires on the board, only 3 or 5cm or so, just enough to be able to grab them with the scope probe.. but then the probe would be sitting under the player... so I would need to raise the player feet by a few centimeters so that the probe can lay underneath it without being squeezed or shorting anything on the PCB...Yeah, I will try that.... tomorrow. Too late and tired this evening.QuoteCould not measure anything, not enough time, the player fails way too quickly once I connect the probe to the scope....Seems to fails equally fast whether I use x1 or x10 though.QuoteIt's a common Sony KSS-140A.QuoteHave not tried any CDR, would need to make one. Don't even know if I have blank CDRs left.... will search in my boxes of stuff see what I can find....

author: shakalnokturn
author_rank: Super Contributor
timestamp: May 09, 2021, 08:54:47 pm
content: I'd definitely review the probing method, above 1MHz the loose wires are going to give you unpredictable results.AFAIK the KSS-140A has no integrated amplification, only diodes.As a side note and I think I mentioned it on one of your other topics: If the player uses a small double-sided PCB attached directly under the transport it is usually worth checking (in most cases replacing) the 3 SMD electrolytics on the hidden side. This involves desoldering the motor terminals. I'll usually make the most of it to clean the position switch contacts too.

author: tautech
author_rank: Super Contributor
timestamp: May 10, 2021, 02:29:19 pm
content: It may be an idea to get a low input capacitance 100x probe as typically they're down ~6pF ....that's if you have sufficient scope input sensitivity for LV work.The additional voltage rating may also be useful when you come to fix that stack of CRO's you have Vince.

author: Vince
author_rank: Super Contributor
timestamp: May 10, 2021, 05:59:38 pm
content: Quote from: shakalnokturn on May 09, 2021, 08:54:47 pmYep that was it indeed, problem fixed !I measured my wires.. were 40cm long, so 80cm total to pick up noise and crap (and add parasitic capacitance).I trimmed the ground wire (not really ground actually, if you look at the schematic) to the bare minimu, 4 or 5cm, just so I have enough to grab it with the alligator ground clip of the probe. Then the wire for the RF signal, I disposed of entirely, and probed the test point directly with the tip of the probe. Was kinda doable if I tilted the player 30°... at that angle apparently it can still play CD's just fine, and it gives me just about enough clearance to see what I am doing, and gently aim the probe where I want it to go. You must no shake or all hells are loose.. but it's doable. Given that you fully know what to expect on the scope, it's already set as required to be able to se the waveform, so you don't need to fiddle with the controls. I just lift the player with noe hand and hold the probe underneath the player with the other hand, and look at the scope at the same time... no shaking allowed...Doing that, it worked perfectly. I could see the eye pattern just fine, even in x1 not x10, and the player was playing perfectly fine, reliably.So lesson learned... long wires to check the eye do (can, at least), matter to the point of sometimes keeping the player from reading the disc.Oh yeah, forgot the most important... the amplitude of the eye is 1.0Volt, well withing spec (0,8V to 1,4V), so I won't be touching anything, works fine. I can button it up and put it up for sale....Well OK, will try and burn a CDR to see what it does, if just out of curiosity, though one is not supposed to read a CDR on an old player so a potential customer can't possibly complain if CDRs don't work well, or even at all.QuoteI don't recall you mentioning that, but my memory is very lousy so...I of course do remember though, you and Gyro mentioning the blue axial Philips on the laser drive. But that's about it.Yep there is a board stuck under the mechanism. Sony always calls it the " BD " board, whatever they mean by that....In this player I see if pretty much integrated the entire player .. servo/motor driver, decoder, and even the DAC, featuring built-in digital filtering/processing. So the transport actually outputs directly analog L/R audio signals ! Only thing that's left on the main board is a chip that amplifies both channels at the same time (no discrete / individual op-amps) and that's about it...

author: Vince
author_rank: Super Contributor
timestamp: May 10, 2021, 06:29:31 pm
content: Quote from: tautech on May 10, 2021, 02:29:19 pmYep, sensitivity is key. Most scopes are 5MV, some 2mV, but the noise floor is high so in practice it's hard to measure with decent accuracy, or get an exploitable / clean /stable enough waveform for signal below 10mVpp, I find. Of course in storage mode I can apply some averaging to help, but the eye pattern looks crap, unusable in storage mode. Only analog mode can represent it properly. YMMV.. but my old Fluke/Philips combiscope just can't make a good job of it in storage mode.QuoteWell regular probes are given for 600Vpp IIRC, so plenty good enough no ? Voltages in the old Tek scopes is about 500V max depending on model.But that's DC, and for DC I have my 10kV HV probe that I can hook up to my DMM anyway, so that takes care of it. I bought it when I restored my first old Tek, the little type 317. It had CRT HV problem, HV was dying as it warmed up, so I bought the probe so I can take measurement to help with troubleshooting, and then let me calibrate the anode voltage properly.But yeah, generally speaking I would love to have lots of special purpose probes for the scope.A mini current clamp for my DMM, to check device consumption. AC current probe for the scope to check switching supplies, or check noise on power rails or what have you.Then a HV diff probe like the one Dave sells, so I can probe on the primary side of an SMPS when I work on whatever device... or to check HV in my old Tek scope as you said, when not referenced to ground. Or just as precaution to avoid blowing my scope(s)....But it all costs money. Other problem is that I heard of someone down under in New Zealand who buys ALL probes for sale worldwide, so the supply is running dry because of him ! Can't remember his name. I think he sells Siglent stuff over there, maybe you know him ?!I think an HV Diff probe would be my next probe purchase, when money permits.Then a current clamp, both for the DMM and the scope.

author: Vince
author_rank: Super Contributor
timestamp: May 10, 2021, 08:40:06 pm
content: Found the few CDR discs I have left, burned one, filled it completely with a random selection of my favorite songs.Improved my probing technique... now safer and hands free : raised the four corners of the polayers with boxes of screws. They are all the same size and are large enough for the player to be stable, but small enough to free enough space on the sides for the probe to stick out. Then sat the probe on a spool of solder to support its weight and bring level with the player.... then I could play all I wanted with the player while playing with the scope.So, this 30 years old player reads CDR just fine thank you very much !!!! Who said they couldn't...And my CDRs are 15 year old (if not more) and I bough the cheapest crap I could find that day at the supermarket, IIRC...Yet, works just fine !I burned the disc at the slowest speed the software would allow, which is x8. Still quite fast if you ask me. Seems like yesterday when a x4 CD player was a state of the art ultra fast piece of gear for your computer...I noticed that the eye pattern as expected, decreased a bit in amplitude, at shy under 800mV, which is the minimum the service manual calls for (was 1.0 with anormal/pressed disc). Also noticed somehow, and I don't have an explanation for that one, that the closer you get to the outer of the disc... the weaker the signal becomes. Not by much of course, but enough that it caught my eye. The inner / first track is almost 800mV as I just said, and the last track at the end of the disc, is more like 600mV. So that is below spec. Still, even that last track plays just fine, never misses a beat, and fast forward/rewind work perfectly, fast and smooth.So basically even with a slightly weak signal, it can read a CDR perfectly reliably, still snappy, perfectly responsive.So I can sell that one with total peace of mind... will even be able to advertise its CDR capabilities despite its old age.

author: shakalnokturn
author_rank: Super Contributor
timestamp: May 11, 2021, 06:27:28 am
content: Quote from: Vince on May 10, 2021, 05:59:38 pmYes BD board it is, attached you a couple of stolen photos, see the less populated side having SMD Nichicons?It was here, maybe not emphased enough though:https://www.eevblog.com/forum/repair/vintage-cd-player-repair-sony-cdp-291-with-transport-issues/msg3531316/#msg3531316

author: Vince
author_rank: Super Contributor
timestamp: May 11, 2021, 06:32:48 pm
content: Quote from: shakalnokturn on May 11, 2021, 06:27:28 amAh yes, I seeeeee !The dreaded SMD caps...Just looked on my poayer, see below. None of these caps. Instead they used more modern Tantalum/polymer caps ? The small axial black packages...Have 4 of them. 3 on the visible/accessible side of the PCB (6,8uF 10V), and one on the hidden side (4,7uF 10V).According to the schematic, they all decouple the +5V rail for the digital stuff (DAC and decoder) only. Not meant for the servo/motor driver IC. That one uses only the +7FV rails and it does not feature any electrolytic.Oh, about the pickup... I said it was a KSS-240A.. was a bit quick. Now that I took a close look while removing the BD board... turns out it uses a KSS-390A instead. Schematic says that the player can be supplied with either pickup.

author: ebastler
author_rank: Super Contributor
timestamp: May 11, 2021, 07:14:13 pm
content: Quote from: shakalnokturn on May 05, 2021, 06:44:05 amStuder/Revox made great tape recorders, for a hefty price.But aren't their CD players just rebadged Philips players (for a hefty price)?Philips CDM drives, same TDA1541s, same op-amps, ...?

author: Vince
author_rank: Super Contributor
timestamp: May 11, 2021, 08:12:41 pm
content: Yep maybe, I don't know... the point of this old message you dug out was not about their technical merits (if they are old Philips inside then that's rather good ! ), but only about the overall build quality and quality feel of their cabinets/chassis/ front panels.

author: Gyro
author_rank: Super Contributor
timestamp: May 11, 2021, 08:30:53 pm
content: Yes, their I/V and audio filter stages are stock Philips circuits. They are probably better in terms of PCB routing, grounding, supply rail noise etc. Pretty subtle stuff though.Edit: Sticking my head above the parapet again now shakalnokturn has done a good job on the Sony.

author: ebastler
author_rank: Super Contributor
timestamp: May 11, 2021, 08:53:45 pm
content: Quote from: Vince on May 11, 2021, 08:12:41 pmHey! What's six days in the fast-paced world of vintage CD players?I dunno... I feel that Revox realized that they had not much to add to this new game of digital audio (except for a loyal customer base willing to pay a premium price for well-designed mechanisms). It does not look like they actually tried to make their versions of the CD players perform better than the Philips originals. They could at least have given them different analog stages if they had wanted to.When it comes to build quality of the chassis and front panel, nothing beats a Philips CD 100 in my view: Massive die-cast chassis, and a one-piece top and front panel which looks and feels like it is milled from a solid block of aluminium. (It probably isn't...) The Philips engineers probably wanted to play it safe in their first CD player, and they did a very nice job.

author: Vince
author_rank: Super Contributor
timestamp: May 12, 2021, 05:30:59 pm
content: Excellent timing : just received my Farnell order. Just before bank holiday Thursday, and the week-end (I work on Friday).So I have both the bits, and some time... some action real soonProtoboard and shift register for the CD371, Electrolube SPG to pamper the CD824 before I put it up for sale, and other bits for my other little design project.Life is good

author: Vince
author_rank: Super Contributor
timestamp: May 13, 2021, 04:11:12 pm
content: Can't beliece it, that CDP-C335 is ALREADY sold ?! I have not even had time to advertise it yet !... Remember the CDP-C305 I sold a days back for 40 Euros, no questions asked ? Was a miracle in its own right... a new miracle happened. I forgot to remove the ad. Was long lost in the abyss of the search results of course, yet somehow last night someone left me a message asking when it would be possible to drop by to test AND buy the player ?! I said sorry already sold, but have his big brother ready for sale if you like, CDP-C335.Guy showed up an hour ago, and did buy it, again 40 Euros, not even trying it discuss the price !Said his own CD player, also a Sony 5 disc changer, packed up just yesterday, his daughter was very sad about this, so daddy rushed online to see what he could find locally... was so happy to find a nearly identical player, tested and "warrantied"...He even brought his old broken player for me to have a look at ! Guy stayed 20 minutes while I was having a look at the thing, in case it was something obvious. Couldn't fix it on the spot, so he said I can keep it !It's a Sony CDP-CE375. Similar but 10 years newer than the CDP-C335 I just sold him.So here I go, hoping to fix it for cheap and make a quick buck from it.Symptoms : drawer does not open, and the player makes a continuous motor noise, never stops.First checked the carousel motor. Its belt was very loose. Replace it with what I could find in my donor drives... a belt that's way too tight, but at least it "works". Good enough for diagnostics purposes.Drawer still would not open, and still that horrible motor noise... found it was the other motor, the one that drives the big "loading" gear as Sony calls it. Easy diagnosis : it's belt was so tired/loose that it flew off of the wheels ! Found the belt laying at the bottom of the chassis...Replaced it with yet another belt from yet another donor drive... belt is much more "fresh", but sadly too long. Still kinda works : the drawer can now be opened and closed. So, Two belts that need replacing, but temporary replacements are good enough to carry on troubleshooting.... because, no, it STILL does not work... this puppy is sicker than your average drive, yet it's 10 years younger hmmmm....Remaining symptoms : the player just will not stop rotating the carousel ! Looking at what's going on on the VFD display while looking at what the carousel is doing... it looks like the player fails to detect the presence of discs : it just spins endlessly trying to reach, say, slot number #3 of the carousel, but it never can't find it !I also notice that it does pause, very briefly, a split second, at each disc.. which is normal. What is not normal I find, is that whenever it pauses to try and (fail to) detect a disc, the carousel is NOT lined up with the CD transport ! Nope, it stops right in between two slots.So that might be a clue ?! Maybe the carousel can't be placed in just any location ? Might need to "synchronized" to the tray, somehow ? I never had this typt of problem with previous carousel changer, so I am not sure this is it...There is a infra-red detector inside the tray, so might want to look at that. Also a switch protruding from the mechanism, into the bottom side of the tray. Might be worth checking that one too.Sorry Gyro, I know you don't love Sony's all that much, but this one is saleable I think so I will try to fix it.. will pay for the part to fix the CD371, see it that way, a necessary evil !Will try and download the service manual, see how it works exactly.At least there is something I recognized straight away : it sports the usual ' BD' board ! Looks like they used that one for 20 years !Any suggestion on where I might go to buy an assortment of rubber belts of various sizes ?!

author: Gyro
author_rank: Super Contributor
timestamp: May 13, 2021, 04:39:08 pm
content: Quote from: Vince on May 13, 2021, 04:11:12 pmAs long as you keep getting rid of them, I'm happy.No real suggestions on the belts. the local UK CPC arm of Farnell (a company acquisition) sells them but not as assortments and probably not useful for France...https://cpc.farnell.com/w/c/audio-visual/av-spares/prl/results?st=belt

author: Vince
author_rank: Super Contributor
timestamp: May 13, 2021, 05:11:42 pm
content: Thanks for the link, at least it shows what's available and at what kind of price.Most of them are noted as "UNBRANDED", which mean that copany buys them for 5 pennies a piece from China and sells them for 50 pence or a pound, in the UK. So might as well get them straight fro China for much less., if I can find a seller.Price on that site are still reasonable though, would make a repair economically viable (depending on how much they charge for shipping...), ASSUMING one ca know for sure what lenght he needs, so that he doesn't have to buy half a dozen of them of various size, hoping one of them would fit.So that's my next question : how do you determine what lenght you need ? Measuring the old belt might not be reliable as it's tired and stretched, eh ?Measuring the inside lengh of the belt, by wrapping a piece of string around the two wheels ? But then, say, you measure 100mm. You would need a belt that's a bit SHORTER than 100mm, so that it makes good contact, has some springiness/elasticity, does not slip etc... no ?So, is there a rule of thumb to determine that ? Like, I don't know... buy a belt that's 10 or 20% shorter than the measured length ?Point is, how to be 100% sure what length you need... so that you know that if you pay shipping for one single belt... at least you are guaranteed that the money is well spent and the belt will work well.Shakal may have a French / local seller in Frog land ? Or an address on the interweb other than the UK so we don't have to pay import taxes and god knows what taxes now apply ?!Found the service manual, let's see how the carousel and disc detection work...

author: Gyro
author_rank: Super Contributor
timestamp: May 13, 2021, 05:49:54 pm
content: Ha yes, belt length is a tricky one. There are all sorts of calculators for V-belts (the power transmission kind where the belt runs on the inner sides of the pulleys rather than the bottom of the groove), these usually have tensioners too.I found a lot of hits for 'belt length', most of them as the above, but there are others from spares suppliers, eg.https://www.turntableneedles.com/How_to_measure_find_right_turntable_tape_player_rubber_drive_beltWith relatively low loads and stretchy belts there probably a reasonable amount of leeway. The link above mentions 3-5% shorter than the belt path. Maybe use cotton rather than string to ensure that you get to the bottom of the groove. If too tight, it might cause additional wear and friction but probably not failure. I don't know if, or how quickly, a tight belt might stretch to a more comfortable fit.P.S. Belt kits do seem to be available on ebay: eg. (obviously a UK one)https://www.ebay.co.uk/itm/402580537942.

author: Vince
author_rank: Super Contributor
timestamp: May 13, 2021, 06:00:46 pm
content: Already making progress !Service manual pretends that if you short some test point on the main board, to ground, it forces the unit to play a CD. Does not say whether that requires the tray to be present and connected up, though....So what the heck, let's give it a try ! I removed the tray, disconnected its cable altogether. 100% out of the way.Grabbed a test lead, connected that test point to ground, well, the chassis.Shoved a CD inside the CDM, clamped it by hand, turning the loading gear manually.Then I powered up the beast and crossed fingers and toes... SUCCESS !!!The player indeed plays the CD, not bothered in the slightest by the absence of the changer mechanism !Plays just fine, no skipping, detects the CD promptly, can change tracks no problem.This player works just fine !So that's great. Now I am 100% sure that the problem lies 100% in the changer mechanism, not the player per se. So I can rule out the player core, it works like a charm.That means it also worth trying to fix this carousel issue, because I now know that once fixed, there won't be more troubles down the line.Me happySo let's see what's wrong with this changer...

author: Gyro
author_rank: Super Contributor
timestamp: May 13, 2021, 06:04:47 pm
content: It looks a lot less cluttered like that!

author: Vince
author_rank: Super Contributor
timestamp: May 13, 2021, 06:30:20 pm
content: Yeah, I much prefer it this way, much better accessibility/serviceability !!Thanks for the info belt-wise. Boy so there are dedicated "calculators", so my question was not that dumb then... it's a real concrete problem...

author: Vince
author_rank: Super Contributor
timestamp: May 13, 2021, 09:36:31 pm
content: Hmmm.... 23H15 here, giving up on the thing for today.There are two IR sensors on the tray, well table as they call it in the manual. I like to call it the tray/drawer.. because a drawer coming out of the slot in the front panel makes much more sense than a freaking dining TABLE coming out of the same orifice !Me thinksThanks to the schematics, it was all easy to test, at least from an electrical point of view... handling these carousel changers while trying to service/troubleshoot them, is a major PITA.Anyway, I managed to test both of them, and to rule out any interconnect/wiring issue, I probed the sensor signals right on the main board PCB, their final destination.1) One is an integrated emitter/receiver, with some shaping circuitry inside, so it output a clean digital signal out of the box. It detects the position of the carousel as it turns. I get a clean logical signal, and it comes and goes as expected when I insert an object between the receiver and emitter. So that one works just fine.2) Other one detects the presence of a disc in the current slot. This one is less sophisticated. A discrete LED and photo-transistor held side by side in a little plastic holder. Pull-up in the transistor collector as you do. So I was expecting a varying analog voltage, and I do get that. I get 5V with no CD present, as expected, then as I bring a CD closer and closer to the sensor, voltage decreases, great, and when I lay the CD on the sensor, I get almost zéro Volt. 0.15V or so. Good enough for the CPU to consider that a low level logic signal, so am pleased.So.... I am NOT happy that these two sensors work, because they were the most plausible suspects, so now I must dig much deeper to get to the real cause of the problem, so more hours and headaches ahead !!! :-(But well, as I say, the harder it is, the more you learn.... so let's keep digging.I checked also the micro-switch that detects the position of the tray. It works fine. Also an encoder that detects the psition of the loading gear.. appear to be doing sensible stuff, I called it good. Opening and closing the tray works fine now anyway, but I thought I would check anyway just for completeness and peace of mind...So, why the hell does the carousel keep turning all the time ?! My next though would have been.. yet again a cooked motor driver IC, like I have in that other player. BUT.... I doubt it is that, because... it does not always turn in the same direction. Instead, it does a very predictable dance : it rotates 2 slots worth CC, then changes direction and rotates yet another 2 slots worth in the other direction, then again 2 slots in the oter direction, etc etc... does it this cycle 4 times it seems, then it stops and the unit displays "ERROR" on the VFD display, and even blinks it to make sure you pay attention.So, since this no erratic dance, it means it's the CPU commanding the carousel, in a determined, voluntary way. So for now, I would say that sensors and motor driver are fine.... and I am left with zero clue as to what to check for next !I would love to have an error code number to be displayed, but it just says "error" that's all. Plus, the service manual does not seem to list error codes anyway. Also, manual is written in Chinglish language(really, Sony ? You even saved money on manuals ?!) which does not help me understand what the service modes actually have to offer me in terms of diagnostics aid...23h35, going to bed. Might wake up tomorrow with a bright idea, you never know...

author: Vince
author_rank: Super Contributor
timestamp: May 13, 2021, 09:39:34 pm
content: Oh, and I forgot.... the rotary encoder/knob on the front panel that's used to select the track you want to play... it's acting up, great !!!According to the schematics it's a mechanical one, not optical. So there is a remote hope that I can try some contact cleaner, but if that does not do it, I won't be selling that player with a dodgy encoder... don't want negative feedback !Won't replace it either of course, would eat any profit I might hope to make when selling the thing.

author: Gyro
author_rank: Super Contributor
timestamp: May 14, 2021, 10:03:49 am
content: Quote from: Vince on May 13, 2021, 09:36:31 pmI did wonder why the tendency towards multi disc players - you wouldn't find any self-respecting vinyl addict using an autochanger turnable (remember those?)You seem to have covered everything that I would have thought of ie, check the sensors - I suppose you checked the signals right back to the micro pins (just in case it has a bunch of dry joints). Likewise the encoder. I don't know if it's possible for the gears / sensors to get out of sync? It depends whether somebody else has already tried to fix it. Just a thought.It's irritating when it's 'deliberately' doing the wrong thing - from your description of the backwards / forwards it sounds as if it is definitely searching for a sensor input that it is not getting (sensor out of sync, dining table position out by 180 degrees?)QuoteHopefully you mean 'Japlish', unless Sony were so cheap that they subbed out their design and manual writing too!P.S. From my past career, I am experienced in understanding and writing in Konglish. Of course, without the 'lish element I am totally screwed! This probably explains my difficulty with Californian, which bares only a passing resemblance to English.

author: Vince
author_rank: Super Contributor
timestamp: May 15, 2021, 12:10:26 pm
content: Sorry for being late... worked on the thing 'til almost midnight last night, was exhausted, too late and tired to report back.Quote from: Gyro on May 14, 2021, 10:03:49 amThere seems to be a pattern indeed, judging but the success of my two 5 disc changers. Also, the guy over at 12voltvids repair channel on YT , commented about this very thing. He too noticed an appetite for 5 disc (carousel) changers (not sure about 6 disc cassette changers though), which he can only explain this way : "You get that hot chick at home, turn the machine on at the start of the date and just forget about it. You dont want the music to stop suddenly while in the middle of.... ahem. ". I don't know.Personally, I do enjoy my old Philips CDC486 6 disc cassette changer. Whenever I work on, the lav it always takes hours on end, I just want some background music. I just hit PLAY when I start working, and power the thing off at 2AM when I am too tired to work on the bench and decide to go to sleep.I really don't fancy having to stop what I am doing every hour or so, to swap CD's ! I just hit PLAY and forget about it. Using a single disc player and getting it it to repeat the disc endlessly, is not a satisfactory option I am afraidQuoteGyro, big mistake here !You are assuming that people are trained and passionate audiophiles ?!Obvisouly nothing could be further from the truth, otherwise CD player manufacturers would never have been able to sell hundreds of millions of their CD players for a couple decades !Also, audiophiles tend to seek perfection (something they can't even define in accurate technical terms) for the sake of it. Most people do things to achieve a goal, not for the sake of doing something as such.The goal of listening to music is to get emotions. Will I have zero emotions if I listen to my favorite songs on a TDA1543 and be flooded with tears wit ha TDA1541 ?! No of course. The later will be more a little more enjoyable, but I would still enjoy my music on the former, as I am doing right now as I am writing this. Because the emotion in the music is not conveyed by its technical perfection... thank god there is more to music than numbers and maths. There is irrationality.Would you not love you other half if she got a cold and her voice sounded different than when you first met her ? I hope not.. because there is more to her than just he voice. You won't dump her or divorce because her voice sounds a little different.So, it's functionality first. As long as the changer put out sound, it's good enough for people.So maybe I could specialize in 5 disc players, knowing they sell better than the single disc ones.Single disc one I could specialize in the old Philips like my CD824, ie old enough to interest Philips collectors/speculators, therefore command decent/worthwhile prices, but too crap technically to be of any value to me, so I am not tempted to keep them for myself and therefore lose money rather than make any...Yeah, maybe with these two kinds of players, I could make buck here and there from time to time, can't hurt, I need every penny to build my house.QuoteAlmost. Accessibility is a pain on this unit, so I did the best I could in my first / quick attempt : I probed on the main board, on the top side of the connector.But since the signals were OK there, I dug farther and pulled the (single sided) main board so I could check the underside (where the CPU is soldered). NO dry joints, traces in perfect condition. The sensor for the turn table is digital and goes straight to the CPU pin. However the signal for CD detection is analog and does not go straight to the CPU. In between there is a PNP transistor and a couple resistors, that invert the polarity of the signal. I checked the output of the inverter, works just fine.So, the CPU does get good table and disc sensors signals. I don't think there is any synchro to be done for the carousel. Manual does not talk about it, and underneath the carousel you can see lots of slots/slits for the optical sensor, carefully laid out to encode the position of the carousel. The whole point I think is precisely to let the CPU figure out by itself the position of the carousel.QuoteIt indeed looks like such "complex" and repeatable behaviour can only emanate from the CPU, something clever... however I am slowly considering that it may not be the case....somehow ?I mean, I am so clueless and baffled, that I am now considering any possibility, as long as it gets the thing fixed ! LOLHere are the things that would make it strange if it were the CPU at fault : the problem is present at ALL times... even if :1) I put the unit in table maintenance mode.2) I open the tray.3) If disconnect the front panel, and the CDM / BD board. leaving nothing but the main board connected to the turntable motors and sensors. In that case, I would expect the CPU at power up to be somewhat disturbed by the lack of front panel and CDM / player, at least sufficiently disturbed to decide there must be something better to do right now, than play again with that bloody turntable...A corrupted CPU firmware ? I guess that's very low on the list...Things that may point to a H/W issue :1) When the carousel moves from one slot to the next.. and back again, between two slots it always, consistently kinda stops, but not really : it slows down to a crawl, makes a sorry "grinding" noise while moving extremely slowly, like a millimeter a second... then all of a sudden starts moving fast, smooth and quiet again... and the cycle repeats. So, this means the CPU is would be programmed to be able to generate analog voltages to command the motor driver IC, so that it can vary the speed. Sound unlikely....2) I sometimes, sometimes, notice that the other motor, the "loading" motor as they call it, the one that opens the tray... well sometimes it TOO does some completely weird things. "analog" kind of things.... Both motors are driven by the same chip.... chip that drives nothing but these two motors...So since I am desperate and the sensor/CPU basic checks lead to nowhere, I am now starting to get at the bottom of things :1) I had to replace the loading motor belt, and carousel belt, since the original belts were too tired / loose to work at all.I dismantled 4 CD players, hoping to find belts in them that would do the job. All I could find where belts that were either a tad too long hence useless, or way too short, like half the size (not kidding). Yet, even at half the size, they would stretch and not break. So, given no alternative for now, I used these super tight belts.So, to rule out a problem with these belts, or a tired motor say, I tested the table outside the CD player. I powered the carousel motor and loading gear motor directly with my lab power supply. Result ? My super tight belts work just fine. Carousel turns effortlessly, smoothy and quiet. The loading motor works fine too. Healthy, smooth.... works just fine.So now I can rule out any belt motor or gear problem. The mechanical stuff does work fine !So if it does funny things, it can only be the electronic stuff commanding it.2) Now next on the list : I will try to power the motor driver IC board (it's not part of the main board), independently, to see if it does funny business or not.I mean, it uses the same kind of driver IC that failed in that other Sony player I am currently fixing as well (waiting for china to deliver that chip...) So maybe the chips from this manufacturer are just crap...The cycling nature of the carousel movements might be explained by a capacitive effect of some sort, potentially ? Potnetially.3) if the driver board does not misbehave on its own, then next thing to do is plug the driver board back to the mainboard, and scope the input signals of the driver IC, to see if they correlate with the misbehaviour. IF they do, the CPU is sending them. If they don't... the driver board/chip is doing it on its own.So, planning on do that this afternoon. Stay tunedQuoteAh well, you know more than I do so... maybe Japlish it is, maybe !Tell me your thoughts : here are below the 3 pages of the manual that pertain to the maintenance mode...

author: Gyro
author_rank: Super Contributor
timestamp: May 15, 2021, 04:36:27 pm
content: Yes, that's Japlish - itwasdesigned in Japan. Very grammatically correct short phrases (some errors this case), and no accidental substitution of inappropriate words, but shows the typical lack of underlying detail that helps explain what's actually going on.Ok, I take your point on the multi-disc players - I remain to be convinced that the benefits outweigh the added complexity though.

author: Vince
author_rank: Super Contributor
timestamp: May 15, 2021, 04:58:14 pm
content: Quote from: Gyro on May 15, 2021, 04:36:27 pmYes, complex they are, and worst of all a royal pain to work on, and way too many gears of fancy shapes. just begging for trouble.Much prefer the 6 disc cassette changers. Simpler and easier to work on.OK, I just soldered and labeled 13 wires... to the connector on the motherboard that goes to the table. This way I can probe any power rail or I/O signal while the unit is assembled, in a working state....That showed that the back and forth movement of the table is indeed commanded by the CPU. Driver board I powered up stand alone, nothing happened, which is good. So either the CPU has lost its mind and therefore the player is good for the scrap pile... or I need to spend more time experimenting, trying to understand how this changer works, in greater detail.However it looks like the motors sound tired... but since I know for a fact that they aren't, that means the driver chip might have weak outputs...Its power rail, negative 10Volts, is solid, no problem there, hence I am suspecting the chipAgain, I could test for this, standalone, to isolate that driver board from the player. Will do that...But... I have a bigger problem right now : the way too tight/small belt I fitted to the carousel motor.... just snapped.. didn't last long.So now, I really do need to order proper belts if I want to go any further.... hoping to find super cheap ones on-line, let's see what I can find...Shakal if you know of a place that sells this stuff in France or Europe (ie not the UK anymore...), please share !

author: shakalnokturn
author_rank: Super Contributor
timestamp: May 15, 2021, 08:26:06 pm
content: I can get you belts cheapish through ASWO on my next order and forward them through snail mail if needed.If you give me the approximate dimensions I'll list you the closest available.As Gyro suggested the most likely may be something mechanically out of sync but I haven't looked at the SM for further clues.

author: shakalnokturn
author_rank: Super Contributor
timestamp: May 15, 2021, 08:43:05 pm
content: Looking at your pictures there are sync holes for the tray ejection and transport lifting, I don't see much for the disc selection though.How is the turning platter disc numbering encoded on the hidden side? Single slot for each? Unique sequence for each position? With one disc loaded have you checked that the reflective sensor works as intended.Once again when testing optical sensors beware of ambient light, I've been caught out a couple of times. Sometimes it's worth turning your workbench light away or off while testing.Other than that maybe check CPU power, reset, clock.

author: Gyro
author_rank: Super Contributor
timestamp: May 15, 2021, 08:50:38 pm
content: Quote from: shakalnokturn on May 15, 2021, 08:43:05 pmGood point, I remember getting caught out by that one on a VCR.

author: Vince
author_rank: Super Contributor
timestamp: May 15, 2021, 09:00:39 pm
content: Thanks for your kind offer Shakal !Hopefully I won't have to bother you on that one.. just check Ebay without any hope, but what do you know... it's not just old Philips players that attract belt sellers... looks like Sony stuff is popular too, my luck !Found a guy in Germany that sells both belts in a kit, for 11,45 Euros shipped.https://www.ebay.fr/itm/274719912069?hash=item3ff6953085:g:FMoAAOSwwlVgTiIoStill 100 times more expensive than what it costs, but since I don't have any relative in the Chinese belt factory, 10 Euros it will have to be. Still kinda reasonable, for 2 belts. If that's all I need to fix the unit then I should be able to make a profit on the thing.Of course if you can get them for 2 or 5 Euros, I would go with you instead !.. but I would have to get the length right, whereas if I get the kit, hopefully I won't have to worry about it...OK will buy that, and if they don't fit well, will measure and contact you...Sync wise, manual gives instructions regarding the loading gear, but nothing about the table/carousel. I will check the loading gear sync then, though I have no reason to believe that the guy who gave that drive to me messed with that... all he did was pop the hood so he could retrieve his CD's that were stuck inside, that's all...What the heck, manual is "only", 3.3MB, so should be able to attach it here, let's seee....This drive is exceptional.... not in good way though : just checked the procedure to adjust the laser drive and check the eye pattern.Manual says that... uhhhhh.... " the drive is designed so that it does not need to be adjusted " !!!!So they tell you how to check the eye diagram, but if it's out of spec then tough luck, can't adjust anything !

author: Vince
author_rank: Super Contributor
timestamp: May 15, 2021, 10:47:08 pm
content: oops, our messages collided...Quote from: shakalnokturn on May 15, 2021, 08:43:05 pmLooks like there is a unique sequence for each disc. For each disc there is a series of tabs that make up slits for the sensor. One disc has 2 tabs so one slit, next one 3 tabs so 2 slits etc, up to 5 slits. So it adds up nicely, makes sense...Disc number one i snot the one with one slit, but who cares, the CPU is free to number them internally as it wishes...QuoteYes I checked carefully for that in a previous message. The sensor for the platter as you call it, gives a TTL digital signal. Works just fine. When I put an object between the receiver and the emitter, it dos switch between ground and +5V as expected.The disc detection sensor is analog though, and it works fine too. when no CD is present I get 5V as expected, and as I progressively get the CD closer and closer to the sensor, the voltage decreases (photo transistor with a pull-up resistor) down to almost ground (0.15V, good enough) when CD is positioned on the platter, as it's meant to be. Signal then goes to the main board where it is inverted by a PNP transistor, then goes to the CPU pin. That part works too.QuoteGood point... tried that, no change at all. Not really surprised since I tested the sensors with full lighting and even this way, they work perfectly fine... but worth keeping in mind for future repairs...Anyway, played with the thing for a bit. Since the table belt has snapped, I turned the carousel by hand, for long minutes, in one direction, then in the other... opening the tray.. closing it.. pressing " PLAY "... tried to see if I could get it to react in some way... and it did react !1) Normally, after doing it's carousel dance a few times, 3 or 4 cycles can't remember, it would then stop and display 'ERROR3. Wel, I noticed that as long as keep turning the carousel by hand regularly, it never gives up and never throws ERROR. It just keeps trying. So I guess that means it sees "some" activity from the platter sensor, which causes the drive to insist.2) With one single disc present, I noticed that it would eventually "build" it'sd map of what slots were empty or not, and after a while turning the carousel, eventually at some point the VFD display would acknowledged the fact that indeed, there is only oe disc present, and it would also get the number right. I put the disc in slot #2, and that's what it displayed. So that's encouraging !3) I managed, twice, after great effort, lots of patience, lots of turning, pushing buttons.... to make it CLAMP a disc, spin it a read it !!!! TWICE !Right now it's playing !So it CAN do it...However, the loading gear is SOOOOOO weak , that it barely can clamp the disc or operate the tray !! ... even though it tested just fine when I powered the motor directly with my lab supply ! So weak that I am sure it tried to clamp the disc several times but I didn't even notice it because it was so slow to gete moving that the player gave up and started trying to rotate the carousel again.Then tried putting 5 discs in the carousel, fully loaded. IT seems to recognize that all slots are occupied : display says so.So it's encouraging.The first thing now is to sort this belt problem once and for all. So I will order those belts.Then see why the loading gear ss so weak, unable to operate without assistance, even though the motor works super fine.Until I receive the belt, there is no point doing further test I think.... so I will get back to you once I have those belts. But since I will buy them from Germany, hopefully I should receive them in just a few days, not a few weeks...Tomorrow, something different on my plate : must work on all the paper work and drawings for the building permit of my garage/workshop. It got refused a couple years ago, the complained about a dozen things... need to rework it and submit it again... need the garage to store all my electronic gear somewhere else than the living room !Stay tuned.....

author: Vince
author_rank: Super Contributor
timestamp: May 16, 2021, 09:34:54 pm
content: OK, did work on thje building permit, pfff... did some work on the dry walls in the toilets though, almost there ! so was not totally unproductive...Worked on the player a bit more in the end ! Because... as I was gathering all the screws and bits in a box, to store the thing while waiting for the belts... what did I see on the bench ?! A belt that was the perfect size for the table motor ! Way too short for the loading gear motor, but just the right size for the table, hooray !So I was back in business, hence I could not help but resume troubleshooting...Worked on the loading gear motor to try and se why it's so weak. Noticed suspicious joints on the driver board, precisely at that motor connector ! Fixed that promptly. Definitely better now, but still far from good, definitely not acceptable. It's having an extremely hard time getting started. Once the drawer is on the move, it gets easier and moves at a normal speed. So it's better, but still need some work.Soldered a couple wires to the two output pins of the driver IC (a BA6780 ) so I could watch the output voltage in real time as the motor is working.No wonder it's so weak/useless :1) When I ask the player to open the drawer : at startup, it gets 3,7Volts or so, wayyy too low to do useful work ! Once the drawer is finally moving, voltage increases to 6V and it opens up at a normal speed, I would say.2) When I then ask to close it, again I get 3,7V at startup, very slow start, but then it does not get better, it goes slow al the way til the end, have to push by hand it to help it, then when it's fully retracted and motor is going to stop, it gets 2+ Volts.I don't know what voltage it's SUPPOSED to get. Tried to figure it out. The data sheet shows that there is a pin that let's you adjust just that. However it does not give details on how it works, how to calculate the thing. The schematic shows that this pin is set by a voltage divider between the supply voltage and another pin no the chip, which outputs an internally regulated voltage.of 4.6V. Problem is : the supply voltage for that chip can be pretty much anything. In this CD player it's a single rail, negative. Runs purely on negative 10V rail (yet can take TTL level inputs from the CPU...).so how can it generate a positive voltage reference, from a negative rail and nothing else ?So that means basically I can't trust this datasheet... so I can't know for sure how much voltage the chip is set to output.Yes, I hear you... "Look Vince, what do you bother retro-engineering this thing, all DC voltages are noted on the schematic, just read ! ".Yeah ? Really ? Schematic says that the outputs are -12.6V and +12.6 V !!! How plausible is that when the chip has a single -10V supply ?!!!Even funnier : look at the schematic for the main board, precisely the 7805 regulator (hence +5V) for the CPU, what does it say ? Input voltage of NEGATIVE 10V, and output of +7.1V !!! Now how much should I trust DC voltages in these schematics, please, tell meLooks like they put as much effort/care in these schematics as did in the translation job !So... I don't know what freaking voltage this motor is supposed to get ! Best I can say is : "maybe 6V, because that's what I measured when the tray was moving at what looked like a normal speed, plus it's what the schematic says... so maybe it's correct at least for these 2 pins...So, why does it get only 3.7V at startup, or all the way when retracting the drawer ?Checked the - 10V power rail, it's solid, does not drop when the motor. So maybe the chip's output are weak, don't put enough current ? Datasheet says 1.5 Amps or so max current, but they don't say it's including both motor drivers, or if it's per motor. When I tested the motor on my bench power supply, had no weak start, but the supply of course can supply 3 amps.What I am thinking is that it might be combination of two things, perhaps :The belt I put as I said, is wayyy too short, so might give the motor a hard time since these have so little torque. It can still do it with the bench supply, but maybe requires more current than the driver IC in the player, can supply.So maybe once I put the appropriate belt on it, motor will require less current, the driver IC will be able ti supply, and voltage will go up, and motor will be happy againI don't know... but I am not wasting time chasing red herrings... I will leaved it at that until I can replace the belt and reassess the situation...That was for the loading motor.Then I worked a bit on the sensors. I told you they tested fine, even in ambient light, when I did a static test and checked with a DMM.So, next step, I scope these signals while the carousel was turning, to get real world data... see below.The table sensor gives clean TTL pulses as you would want/expect.Then the disc sensor, which gives an analog voltage. We can see that it gives a clean, sharp negative pulse (inverted into a positive pulse by the time it gets to the CPU), like clock work, every time a disc passes over the sensor. Looks good to me ?!..........Yes, yes.... I did try putting the cover back onto the unit so that it's dark inside the thing... that does not change anything at all.Every once in a while, really rarely, the carousel slows down not in between discs, but very near the axis of the spindle. When it did this, I forced the carousel (takes quite a bit of force, the bugger is very strong) to be aligned perfectly with the spindle, and hey presto it clamped the disc (extreeeeeeemly slowly, though) and it played music !So for now, I will say that :1) loading mechanism and its sensors work just fine, just need to fit the proper belt.2) problem is limited to the table, player just can't detect the position of the table, despite receiving what looks like clean and valid signals from the relevant sensor. It's still a mystery to this day....Nearly midnight, gotta work tomorrow like the rest of you, so good night !

author: tautech
author_rank: Super Contributor
timestamp: May 16, 2021, 10:01:02 pm
content: Thinking out loud.........Would the tray and carousel sliders/bearings/bumpers/guides benefit with some of that special plastic grease you have ordered ?

author: Vince
author_rank: Super Contributor
timestamp: May 16, 2021, 10:07:23 pm
content: Have already applied the stuff everywhere in there !Somehow the slider and loading gear were completely void of any grease, like the factory back then didn't deem necessary to use any, hmmm.....

author: shakalnokturn
author_rank: Super Contributor
timestamp: May 17, 2021, 12:00:46 am
content: For your slow tray wait for the right belt as decided. Too tight and you get a lot of extra friction on the plastic axis in some cases.On the platter have you checked "S200 rotary encoder, table address detect"? If there are both electromechanical and optical sensors for platter angular position there is a possibility that the mechanical sync is bad or that a switch has a bad contact.Is the 6 conductor FFC in good condition, breaks aren't always easy to see.I can get most small "square" belts for 0.5 to 1€ (excluding VAT and postage).

author: Vince
author_rank: Super Contributor
timestamp: May 17, 2021, 06:07:26 pm
content: Quote from: shakalnokturn on May 17, 2021, 12:00:46 amOh great, that sounds like a reasonable price ! So that means I wasted 10 Euros on Ebay, my profit margin could have been much better !Oh well, that will be for next time !QuoteYep I checked it yesterday (pics below), because it's name sounds "promising".. Table.... Adress.... sounds good !I opened it to check the internals of it, Looks fine to me. All 3 "fingers" are in good shape, still "springy". They make a reliable contact when I checked all 3 fingers for continuity with the DMM. I put some contact cleaner in the thing anyway, can't hurt.Quote... that encoder actually does not encode the angular position of the platter/carousel, at all. It's not even located on the table like the other two optical sensor. Nope, that encoder is linked to one of the loading gears, on the chassis. So it can tell the CPU in what "state" the loading mechanism is, but that's it. It can not tell the CPU the position of the carousel...But, I checked it anyway, for good measure, and because I have run out of ideas....QuoteYes I checked it a few days ago. Looks like new and all 6 conductors check good for continuity. Also, the wave forms I attached in my previous message where scoped on the motherboard, so the entire signal path is taken into account.Have something new on my plate as of 30 second ago. A neighbour just brought me a dead beefy industrial 3 phase motor speed controller he bought decades ago. Telemecanique "Altivar".. a boat anchor. Said I could have it for parts if I help him wire another a newer controller he bought as a replacement. Old too, but newer, Altivar n° 5. I am not into electromechanical stuff but well, it's still made of electronic components hey...Lots of good stuff to salvage in the thing. Beefy power resistors, beefy diodes and transistors, or thyristors rather I guess... beefy caps, beefy everything really !Who said nerds are not social people..... having my lab on display by the living room window, actually intrigues and attracts people, they come to me... it turns me into a sociable person, who would have thought...

author: Vince
author_rank: Super Contributor
timestamp: May 17, 2021, 07:51:35 pm
content: Huuuuu...... just checked that CD player on Ebay.... goes for 60 to 100 Euros or so, "as is"...A serviced unit might be worth more than the 30/40 Euros that I thought, then !My first 2 players as well... I sold them so quickly, and the buyers didn't even remotely attempt to lower the price... it's suspicious ! Maybe I could have sold them for 50 or 60 Euros ?! Sounds a bit high to me but well, will try next time, see what happens... nothing to lose !Motivates me to dig deep to try to fix that mysterious table issue...

author: shakalnokturn
author_rank: Super Contributor
timestamp: May 19, 2021, 07:19:18 pm
content: I don't know how you do it... I've been trying to sell a working Kenwood DP-850 with new belts and refreshed solders for 35€ shipped for over a year now! Actually I handed it over to an acquaintance who has a vintage HiFi store today, maybe he'll get rid of it.

author: Vince
author_rank: Super Contributor
timestamp: May 19, 2021, 07:45:08 pm
content: That looks like a nice player, would not mind having it !Looks a lot like my old Toshiba.35 Euros INCLUDING shipping ?! Shipping is 10 Euros or so, not including the packing material ! Even if you got the player for free which I am sure you didthat's only 20 Euros for your time and belts... for ove ra year of waiting ?! Not worth your time indeed !Maybe I just got lucky then. The two buyers happened to be local and their player quit the day before.I will see how my other players will be doing when I finally have them fixed... probably won't get as lucky !Well if they don't sell I will just keep them for parts and move on... I bought them all only to get experience, not to make money... if I can shift some of them to recoup some of my "investment" great, but if not, won't cry. Selling 2 players at 40 Euros already recoups a significant part of the 300 Euros I spent in these 20 or so players...Just received today a CDM12.1, hoping that would fix my Philips CD 720. Just like last time I ordered a CDM12.1, ad says it's "NEW".. but clearly isn't at all... crusty looking wires and solder joint crusty everything... and they did NOT even short the pickup flat flex !NOT holding my breath on that one, but well, might work well enough for me to dare putting the drive up for sale...Philips CD824 is ready for sale. Tray gear and belt replaced, fresh plastic grease everywhere, did help make the drawer mechanism sound a bit less shitty.

author: shakalnokturn
author_rank: Super Contributor
timestamp: May 19, 2021, 08:38:54 pm
content: Quote from: Vince on May 19, 2021, 07:45:08 pmF'ing eBay has become a right rip-off, I used to ask for at least partial refunds in similar situations, now most sellers accept returns so unless you're willing to pay to return and expect them to be honest when they weren't from the start... You're stuffed!Now I live with the bought defects and lost money, give negative feedback and move on.I just avoid eBay when possible, I've had better customer support from AliExpress in the past years.I'll have a quick look at that Pioneer CD player previously mentioned tonight, I'll let you know if there's a spare lens going soon. I have a Sharp CD to check too.Need to get some stuff out of the way to buy more dead TE.Missed a MX54 at 25€ on Leboncoin this afternoon, the seller said a lot of people had asked... Really?

author: Vince
author_rank: Super Contributor
timestamp: May 19, 2021, 09:24:01 pm
content: Quote from: shakalnokturn on May 19, 2021, 08:38:54 pmDidn't have much choice but to buy on Ebay, got it for 10 Euros shipped.. anything more than that and I would sell the CD player at a loss (assuming I can manage to sell it, that is...). So it was either I tried this, or not spend any money on it and just consider it a parts unit...But hell, maybe it works ! LOL Previous one was used too yet it worked just fine. So maybe I will get lucky with this one too...QuoteYeah there are other web sites / places indeed. Bangood or god knows what else, but it's a pain having to create multiple accounts and check 10 different sites for each and every time you need the slightest little thing.. OK I am lazy I guess...QuoteThanks, crossing fingers !Worse case, since I have absolutely nothing to lose, I was toying with the idea of, please forgive me... pull a lens from whatever parts unit I have laying around, and see how it breathes some life into the Pioneer !QuoteSame here ! I am starting to feel the urge to get rid of all these CD players and get more TE !QuoteWow !Good deal indeed ! I didn't even see that ad ! Got removed instantly. I missed two marvelous TE deals too, the past few days. Posted on TEA about it. Still crying.There is a nice MX 53C in pristine condition in its original box, with its test leads and booklet/manual, for 40 Euros. That is (still available) a nice opportunity too, but sadly the seller says he won't ship... WHY ? Not that it's fragile or heavy or large....So I gave up on it.... but I already have a dozen MX 53/54/56, so I guess I don't really need yet another one... It's so hard to be reasonable with TE !

author: shakalnokturn
author_rank: Super Contributor
timestamp: May 20, 2021, 08:48:55 am
content: Quote from: Vince on May 19, 2021, 09:24:01 pmI inquired on that Tek 224 too, didn't have a chance either... At least the seller bothered to respond.The Pioneer CD player seems to be working. (I'll have to check the audio output some time all the same.)The original pickup was sensitive to vibration at the best, laser power had to be turned down to detect CD, but the hidden side of the lens was dirty so I assume that it had been turned up at one point.Anyway I unstuck the lens again to fit it on the pickup from the sacrificial 6 CD player. Much better!I think your plan to throw the odd lens on the pickup and see how it goes is reasonably insane.I measured the lens I had although my Pioneer pickups differ slightly from yours. Inner diameter: 6.33mm, outer diameter: 7.33mm, overall hight: 3.41mm, focal distance: 4mm approx.

author: Vince
author_rank: Super Contributor
timestamp: May 20, 2021, 09:50:30 pm
content: Quote from: shakalnokturn on May 20, 2021, 08:48:55 amI like your styleMight give it a try, nothing to lose...Plus the front panel being cracked I can't sell it any way... so it's all just for the fun and curiosity to see what might happen...Philips CD720 : before replacing the CDM12.1, I tested the unit again, as it's been 2 weeks now since I last touched it. Player had random difficulties detecting or playing a CD. But today it worked just fine ?! Could even handle my test CDR no problem !Okay, I do remember that I did spend some time fiddling with the laser trimmer to try to get it to behave as best it would... but I can't remember that I managed to get it working 100% right.... otherwise why would I have ordered a replacement CDM ?! I Think I losing it...Checked the eye pattern, got almost one Volt. Not not bad for a 30 year old player, and plenty enough in practice to read CD's just fine.But, I replaced the CDM anyway, if just to see if the "new" one, that looks even more crusty than the original one, would work at all.It does work, and the eye pattern strangely, is 100% the same amplitude. Player behaviour too. It's like I did not replace it.... so I left that "new" CDM in place, and will keep the original one in a safe place... the CDM is common place so it will probably be handy one day...However a new problem arose while I was testing the bloody thing : somehow I now had sound coming out only of the left speaker, nothing from the right speaker !Turned out to be a break in the audio cable... yes, this player is so cheap that it does not even have RCA audio jacks at the back... it's got an audio cable hard wired, sticking out of the player (same for the power cord !). I HATE hard wired cables, a pain !!!It connects to the motherboard via a little 4 way connector.If nothing else, I needed female to female RCA adapters so I can plug that cable to my test cable that goes to the amplifier ! A pain ! Of course I don't have such genre changers.. so I made some up, using RCA jacks I had laying around, salvaged from god know what... they have funny colours to them, must be video jacks not audio, but who cares... it works well enough...Removed that connector, cut 10cm worth of cable to get rid of the break, soldered the 4 wires directly to the motherboard where the connector used to be... yeah I know it's crap... but I wanted to get this thing to work right now, and for as little money as possible... it's super crap layer and I have zero remorse sorry !There is obviously a beefy strain relief plastic thingie that clips in the chassis, so it's OK....So, that player now works fine, I can put it up for sale !!!Next. This evening I received the belts for the Sony changer... new loading belt is much skinnier than the one I put... but it's conform to the original, so I tried to trust it...Glad I did. Tray and clamping mechanism now work perfectly, and even better : the PLAYER / changer now works like a charm ! Carousel works just fine now, this mysterious problem that got me to pull my hair out, is GONE !Unbelievable... a (very) tight belt was enough to take the loading mechanism to a crawl and also induce weird problems with a mechanically unrelated carousel ! I guess the loading mechanism being so weak, caused many timing issues that confused the CPU, did not know how to handle them.Lesson learned ! That was an interesting repair then, glad I did it ! Now I know what a tight belt can cause ! Was also fun going to town testing in detail the two optical table sensors, analog and digital. Also, taking the encoder apart.So that's great !But.... I still have 3 lesser problems :1)Player can read a pressed/ normal CD just fine, but no joy whatsoever with my test CDR. Sadly as the manual states that you can check only check the eye pattern, but that there are no adjustments provided ! So that's too bad. I will just have to accept it and carefully NOT talk about CDR compatibility when I put it up fr sale....It's funny though, that this ONE modern player, marketed in 2001, only modern one I have... is modern enough to be CDR "enabled"... yet it can't handle them... whereas alllll my other players, which are 10/12 years older, can ALL read my CDR jsut fine even though they are not supposed too !I guess it only foes to show that yet again.... newer does not always mean better....2)The track selection rotary encode on the front panel that's playing up.... can't possibly sell it like this. Need to have a closer look at it. Hopefully it's not sealed and I can spray some contact cleaner in it... or else I would have to take it apart or drill a tiny hole in it... but I have never done it, so hoping I won't screw it up3)Even more annoying, see this short video clip I made, a mechanical problem with the tray :It makes a horrible noise when it closed (it's fine/quiet when opening). Looks like the gear that catches and drives the tray, has problems catching the track underneath the tray.I don't know why... all these gears in the loading mechanism are quite beefy and in perfect shape, not damaged teeth what so ever, and it's all greased.At first I though OK that's because I did not put back all the screws that secure the metal brackets that keep the tray in place on both sides... so I put back all the screws.... but no change, still makes the same noise.I guess I don't understand how to put the tray properly back in place ? It is a bit of a complex mechanism, especially with the " Ex-change" feature, where you can open the tray WHILE a CD is playing...So I need to work on these issues, then it's going for sale as well...

author: shakalnokturn
author_rank: Super Contributor
timestamp: May 20, 2021, 10:30:58 pm
content: Quote from: Vince on May 20, 2021, 09:50:30 pmQuote from: Vince on May 20, 2021, 09:50:30 pmThanks, I'm sure this one was a purely unintentional mistype. Like your style too anywayQuote from: Vince on May 20, 2021, 09:50:30 pmThe best I've found for those situations without disassembling or replacing is to stand the axis upwards, trickle a small amount of white spirit down it, rotate plenty until you feel a difference, trickle some contact cleaner the same way, rotate plenty.The grease stiffens enough to cause problems.Quote from: Vince on May 20, 2021, 09:50:30 pmIIRC that's typical of a bad mechanical sync the driving gear is probably a tooth or two ahead (or late). I've also seem some trays that would vibrate on their worn plastic sliding guides, some grease usually does the trick here.

author: Vince
author_rank: Super Contributor
timestamp: May 22, 2021, 09:28:29 pm
content: Quote from: shakalnokturn on May 20, 2021, 10:30:58 pmTypo it is, of course !Had to be a typo because I didn't even know that word existed at all !Had to look it up... now thanks to you pointing out my typo, I added a new word to my vocabulary... though not sure I would get to use it, seeing I never heard or read that word since 1998 when I moved to the UK. But Mnem over on TEA likes to use weird words and expressions so maybe he will use it one day and I can say AH, I KNOW THAT ONE !Quote from: shakalnokturn on May 20, 2021, 10:30:58 pmTook the front panel board out to have a look at the encoder. It was pouring out what looked like perfectly fresh/good grease out the shaft. So I was rather dubious that its misbehaviour would be caused by crusty grease or dirty or corroded contacts inside. So, since I am lucky and it turns out it's NOT a sealed encoder, I immediately proceeded to open it to see what I could find inside. Glad I did. It was immediately apparent that the grease and contacts were just fine, and that the problem was most likely rather mechanical in nature : see macro shot of the thing below. There are 4 contacts/wipers in the thing, one in each corner. The two bottom ones (circled in green), which each have 3 "fingers", look fine. They are electrically connected together and form the "common" pin of the encoder. However the wipers in the top left and top right corner, which correspond to the two "channels" of the encoder (circled in red) look out of whack eh ? They each have two fingers. The left wiper has its fingers collapsed, touching each other. The right wiper had its fingers spread apart , forming a Vee shape. So I bent all these fingers back into shape, then bent all fingers of all 4 wipers a little upward, to make sure I get a good contact/spring action on the shaft. Then put it all back together and I am glad to report that it now works SO MUCH better and more reliably ! I consider this a fix. Works plenty well enough for me to sell it without shame.That's the first time I ever take an encoder apart, never mind try to fix it, never mind successfully ! So it's quite encouraging ! I therefore won't hesitate to do it again if need be. It's quick and easy to do. Just need good eyes and a very tiny flat head screw driver.Quote from: shakalnokturn on May 20, 2021, 10:30:58 pmFound the problem for that one too ! Not a sync problem. I was simply missing a little plastic piece !See picture... there is a little black plastic bearing/bushing/roller whatever ever you want to call it, that mounts atop the axis of the gear that drives the tray. With this piece in place, the gear is now perfectly sitting inside the track under the tray, no play, no bending possible... works like a charm, problem solved !!I fond this plastic piece laying on the bench, not knowing WHERE it came from ! Was wondering where the hell it was supposed to go... was totally clueless. Then I thought hey, looks like maybe it could fit on top of the gear ? It fit perfectly ! So I checked the manual for the relevant exploded view of the mechanical stuff, and yes indeed, it show this piece in there, no doubt !So, since it was looking good, I put the tray i place, powered the thing on, and it worked perfectly first time ! It was that simple !I was not doing anything wrong, I was just missing a stupid little part without knowing !I guess it must have stuck (due to the grease) to the underside of the tray, when I initially removed it. That way I did not notice it. Then after handling the tray 2 dozen times on the bench while working on the player, the little bastard must have come off and fell onto the bench... for me to notice much later then wonder where the hell it came from !Anyway. all problems solved, this player is fixed ! I put it all back together, just need a little clean before I take pictures of it, then off for sale !Pickup is tired I think, since it can't read my CDR, and is on the slow side at detecting regular pressed CD's... but well, laser can nont be adjusted on this particular unit, so I will have to leave it like that. it works none the less, so sorry, will sell it like this...So in the end, all it needed was a couple belts, and the encoder taken apart ! too bad I spent 10+ euros to buy the belts on ebay rahter than getting them from you... I just wasted a good part of my profit margin, too bad. Luckily the drive was given to me, so cost me zero. So any money I make above 10 Euros, is profit.I am thinking sometimes of registering a side business, a "fake" one, just an empty shell, just so I can have a registration number so I can be eligible for a "pro" account with spare parts suppliers like you do. From what I gather, it takes only a few clicks on the interweb to register a small business, it's free and you don't pay any taxes if you don't make any significant money. So it should not cost me anything to have a "business"... would need more digging to confirm this, though, or course !So I have managed to fix 3 more Cd players then... that Sony changer, third one, then the Philips CD824, then the super mega crappy Philips CD720.Let's try to flog all that now !See, Gyro ? I am getting rid of them, bit by bit !

author: Vince
author_rank: Super Contributor
timestamp: June 05, 2021, 10:52:45 am
content: Shakal you won't believe it ! I did it AGAIN : I have just sold that Sony changer !First too at an incredible 40 Euros in just a few days and without even any attempt at negotiating the price... doing it once was incredible enough, but doing it twice is... a statistical oddity ?! too good to be true.well, now it's not two but 3 in a row !Given that at 40 Euros the first two sold so well, I increased the price this time to a silly high 65 Euros, just to see what would happen !Got lots of "views", 50 or so, amazing in itself, but no takers, nobody contacted me. After only 7 days I lowered the price a bit to 60 Euros, still through the roof.https://www.leboncoin.fr/image_son/1988296127.htmGuess what ? Last night, only 4 days after updating the price, AGAIN a guy took it, full price, no questions asked no nothing ! He didn't even message me, he simply clicked the "buy" button on my ad page, that's it !!!How can that be !3 identical stories in a row, it's beyond the laws of physics ! I think I just found me a new job !Good thing because I am about to lose my current one... they are dicks and I need to quit real fast before my mental health goes haywire.Now need to go out today to buy some packing material so I can package it properly, as promised in my ad...

author: shakalnokturn
author_rank: Super Contributor
timestamp: June 07, 2021, 10:42:52 am
content: You must be kidding, either that's a lot of good luck or something in your adverts reassures buyers.I suppose mentioning that players have been serviced and that you'll accept returns does help in some way but maybe the most reassuring is seeing all the test equipment in the background... It gives you the impression that they're coming from a repair shop. Your pictures actually made me want aCD playeroscilloscopeI have a nice JVC XLV-264 to sell I'll try a higher price on that one, unfortunately I have less of an electronics lab than you do, I won't be able to have a nice TE background in my photos...I remember your topic on the Radiola CD player with a defective LED driver, funnily I'm trying hard to save a DSO (that doesn't want to be saved), last night troubleshooting problems in the front-end PCB I ran in to two M5451 shift registers. Obviously here they're not used to drive a display.https://www.eevblog.com/forum/testgear/gould-ultima-nicolet-accura-dso-software-needed/msg3582435/#msg3582435(One of the longest and least captivating TE repairs of all times, all the same I did get a little more input than for the OX 2000 DSO...)

author: Gyro
author_rank: Super Contributor
timestamp: June 07, 2021, 07:38:39 pm
content: Quote from: shakalnokturn on June 07, 2021, 10:42:52 amIt may seem strange now, but that wasthisthread.

author: shakalnokturn
author_rank: Super Contributor
timestamp: June 07, 2021, 07:56:51 pm
content: Quote from: Gyro on June 07, 2021, 07:38:39 pmYes, I realised that just after postingDidn't care to correct myself, feeling that getting confused on the topic was saying something anyway.I vote the topic should be renamed: "Vince's CD players...(To be continued)"

author: Vince
author_rank: Super Contributor
timestamp: June 07, 2021, 08:15:39 pm
content: Quote from: shakalnokturn on June 07, 2021, 10:42:52 amYes I try to put in my ads everything that I would want to see if I were a buyer. There is a gazillion old CD players for sale but none that inspire any level of confidence. So I try to instill as much confidence as I can... I think that's what makes them stand out and it appears to work. So, I keep in that vein...QuoteHey look what appeared just now :QuoteBeen a while since an affordable 700 series has been for sale !As for me I am waiting for a TDS 784D (or better yet a more rare 794D...) one day, when I am rich and no other priorities.QuoteHmm... a few for sale on Ebay. Usually prices on Ebay are inflated, yet this particular model seems to sell for very littleOne for 39 Euros on offer, another for 25 Euros "buy it now"...QuoteI can't quite believe that !You are the pro, I am just the hobbyist here !Only decent piece on my shelves is the TDS544A but YOU sold me that one !Oh yes, I have a cool TDS 694C, 3GHz 10GSps on each of the 5 channels... but of course like of the 694C, the trigger IC's are cooked so it can only trigger manually or from the external input. But still cool !! I can always get en external trigger circuit and hook it to the external trigger input...There is still lots of basic TE I don't have ! For one you have a cool EPROM reader, indispensable tool !And you have a life time experience fixing stuff, I can't buy that !QuoteI sense a bit of sarcasm here ?!Yes, YES, I will get round to wiring that chip and get the player to display something other that garbage, I promise !!! I apologize deeply for the delay, I know I suck !QuoteHmm, interesting indeed...QuoteWow.....just.... wow.... I admire your perseverance on that one !!!!I had my share of GOULD scope last summer, never again. Just crap, utter crap, no more... no more !That one is decent spec but not worth your time... so much time spent and hair pulled because of it already ! You will never get your money back, give up before it drives you completely insane !Even if you manage to fix it, nobody will want it, or not for a a lot of money anyway... A TDS 500 Tek with similar spec no problem, but a GOULD.... it's like you old Lecroy scopes, IIRC they did not sell easily (have you actually managed to sell them BTW ?! )I am thinking that making a profit is not your primary goal... I think it's more a mix of masochism and the love for a good technical challenge, and hating giving up. You just can't take NO for an answer !!!I mean, how many people do you know that would fix a TDS 500 CRT with a Minitel fly back transformer ? You're the only one my friend !!I do admire you for that... my Minitel hero.QuoteI have given up on Metrix scope. They just are junk and made NOT to be fixed/serviced. I hate them, I don't touch them, not even with a barge pole, even a super long telescopic one...no. Just... no. Not to mention the consistent lack of service manuals. Metrix just didn't give a shit about serviceability.I would even say it's worse that than that GOULD 1604 I fixed last summer, and that does say something !!!

author: Vince
author_rank: Super Contributor
timestamp: June 07, 2021, 08:17:53 pm
content: Quote from: shakalnokturn on June 07, 2021, 07:56:51 pmOh, so there was no sarcasm above then, sorry !QuoteNo no no, I WILL get round to fixing the Radiola, I promise ! I have bought and received all the parts, gotta do something with them now !

author: shakalnokturn
author_rank: Super Contributor
timestamp: June 08, 2021, 11:23:16 pm
content: Let me help you take this even further off-topicYeah I saw that TDS 754D. If he'd let it go for 200€ maybe...I have enough scopes for now and just spent some money on a (hopefully working) spectrum analyser.I'm not much of a pro lately, haven't been finding much time for electronics. I do have a decent weight of TE, just nowhere to expose and use it conveniently for now.A pitty for your TDS 694C, are you aware of this:https://www.eevblog.com/forum/testgear/least-expensive-but-reliable-used-market-scope-with-at-least-1-ghz/msg791170/#msg791170I think I've seen more detailed information around on that solution, maybe not specifically on the 694C though. If curious ask around...I'd be curious to see if an alternative fix to the trigger could be done with something like an ADCMP580 (/581/582) if someone with a working scope can document the ins and outs of the original IC.You probably don't even need that fast a comparator as long as jitter is low enough.You're right, Gould and Metrix belong in the same nut sack, the best Gould I've had so far was a Hitachi rebrand.The idea of the Gould Ultima 500 isn't that bad, just the way they've stitched the wretched thing together is pretty degrading, besides the one I was sold was a compilation of defective parts.SWMBO said the same as you: "you're wasting your time, it's an unknown model no one will buy it"Anyway you're right I won't take a NO from a machine. Either it ends repaired or axed. I'm getting there slowly... (Looking for the axe right now)Yes I sold the LeCroy's 9344C, 9354, 9450, Metrix OX2000 (easier than expected).Also the Tek 2230, TDS 320, Hameg HM203-7.

author: Vince
author_rank: Super Contributor
timestamp: June 10, 2021, 05:20:11 pm
content: Quote from: shakalnokturn on June 08, 2021, 11:23:16 pmYeah bring it on, I like it when you talkdirtyOT to me !QuoteHmm yeah, dreaming of one all the time, but sadly cheap defective old HP units still cost fortunes even broken, so once you dial in the gamble they represent, it's not worth it, might as well buy a brand new one for not much more, that works ou of the box, more reliable, and comes with a guarantee.QuoteShame... last summer when I was sweating rfioxing this horrible Gould scope, you said you were performing your talent on the dining table because the new house was still not finished ?!That's extreme... lab room still not habitable ? Still no bench, still sharing space with the chicken and salad ?QuoteAh yes I had forgotten about that ! Yes I must try it one day ! But I need to use a decent hot air station if I want to stand a chance of success. MY cheap 40 Euros station just won't cut it, I would just ruin the board...Need a "Quick" station or its recent clone from Atten, which I saw priced as low as 150 Euros ?!MIght have been a promotion don't know, but still.Price has now become affordable so I will definitely get one in the not too distant future.QuoteWow, how do you know the pinout and functionality of that chip is the same as the proprietary Tek chip ?! Quite a gamble eh ?!Or you mean use that chip as an external circuitry feeding the external trigger in put of the scope, as I suggested yesterday ?QuoteA wise wife it must be, she is a keeper !QuoteI will send you an axe to shorten the agony, just tell me your favorite colour !QuoteOh, quite successful then ! All the Lecroy sold in the end, good !Didn't know you had a 2230. I contemplate one just to complete my Tek 2000 series "collection"... but have obviously zero need for it given I have a 2232 already... which is in need of a little TLC / fixing up when I get time for it... beam just won't focus, scope did not like its year spent in storage... neither did my rack mount type 5111A that's now extremely ill, poor little thingCDM12.1 ..... the 30 year old salvage one that the Ebay china seller pretended to be NEW. I let it pass originally, 2 weeks ago when I received it. Didn't want to bother. So I left no feedback good or bad, just ignored the guy.Unfortuantely (for him), yesterday he sent me an (automated I guess) e-mail ASKING me to leave feedback, and even going as far as INSTRUCTING me to leave a 5 STAR feedback !! This guy is provoking me ?! Is he suicidal or what ?!So this time I obliged and left a minus 20 star review, with a comment telling it how it is, basically " RUN AWAY !! Kepp your money, prenteds its new but is clearly a 30 year old crusty salvaged unit, and the pick-up flatflex is not even shorted/clamped !!! KEEP YOUR MONEY RUN AWAY as fast as you can !!! ".Guy replied saying hey you can't leave me negative feedback, it will hurt my business badly !!! Let me give you a partial refund (paid 10 Euros for the thing), let's talk !!.Did not reply. Today he wrote again, BEGGING me to find a solution, to discuss, call me his "friend" (eh ?!), and this time offering a FULL refund...I am done with this guy, I won't reply to any of his messages. He fucked with me and asked me for my feedback, now he needs to be held accountable for his actions ! That's life sorry bob ! But I am not worried for the Ebay "reputation" of his business.... I am sure one of his Chinese buddies already has developed some virus/malware that can manipulate the Ebay servers to removed negative reviews from this account all by magic !!!How can these scum bags of sellers fuck with people and seriously expect to be get a 5 star review with just a couple Euros refund ? Do they think they can buy people with some silver money ? Really ?You can keep my 10 Euros my "friend", and also keep my negative review, FUCK YOU !!!!!

author: shakalnokturn
author_rank: Super Contributor
timestamp: June 11, 2021, 12:22:01 pm
content: Quote from: Vince on June 10, 2021, 05:20:11 pmStill the same uncomfortable situation, not moving fast.Quote from: VinceI get plenty done with my Atten 858D+ sometimes a little preheat from underneath makes all the difference. I find the tool would gain a lot by having a supple silicone cable. Make sure you train on disassembling various types of PCBs.Quote from: VinceNeither really... I seriously doubt the ADPCM580 has a similar pinout, functionality I expect to be very close.I wasn't thinking of use on Ext Trig. either, but rather fitting it in the scope in place of the defective Tek trigger IC's, either dead-bug style or on some kind of adapter board/flex.Quote from: VinceI sold all the LeCroy's I wanted to sell, still have a DDA-120, LT354, 9354M, 9354L, 9344, 7200, shattered 9384...Funny your 2232 is out of focus, when I switched my 2230 on after almost 2 years storage because I decided to sell it, it was out of focus too, checked all the high value resistors, cleaned PCB and other obvious stuff but it turned out that replacing the Murata HV multiplier solved the problem. Although working, the replacement part was far from new, this further motivated me to sell the scope ASAP...Quote from: VinceI'm not sure how eBay functions these days, all I know is that I much dislike it on the whole. I recently gave negative feedback for that non-new PCI9050 bought for the Gould DSO, next time I checked the negative feedback had been removed... I then tried the "want to return goods" procedure saying that either I wanted money back or to leave them the feedback they deserve. I'm meant to be refunded (maybe) even if I have no intention of returning the part.Anyway, let's get back to CD player LED drivers....

author: Vince
author_rank: Super Contributor
timestamp: September 18, 2021, 12:05:29 am
content: OK... 3+ months later, I am back on CD players !I have run out of luck selling them. The first 3, the 5 CD changer Sony players sold extremely well, in a matter of days and for top money, 50/60 Euros... then and bit later I managed to sell the crappiest of all my players, the Philips CD720 IIRC, for 35 Euros, a miracle.But the Philips CD824 that I spent 10+ euros to replace the gear/belt kit for the tray... doesn't want to sell, even though I advertise it half the price they go for on Ebay. So I might try to sell it on Ebay instead...But well. I have run out of luck. There is just no money to be made with these things, can't find parts, and when you can it still doesn't make any financial sense to buy them...So I got rid of an entire pile of them. All those that were not economically repairable, ie all of them...Salvage all the circuit boards of course, a box full of them now, and scrapped the rest.Makes for some much needed room.So other the CD824 which I will sell one way or another, those that are left I am going to keep I think. Still, that's half a dozen of them !- Philips CDC 486 6 disc changer, of course, since that's my youth/family player, that I fixed for my dad last X-mas and that he gave to me. It's my daily driver that plays every morning when I shower and every time I work at the bench.- Another of the same : stumbled upon it, 50 Euros, like new, lower miles than mine, works perfectly and even came with the original remote. Dad lost our one. So that's super. So I bought that one for parts, to make sure I can keep mine going for a long time.- My two old rebranded Philips CDM11/4 + TDA 1541A : the Radiola CD371 and the Toshiba XR-9128.Then a couple outsider that I may keep or not in the long term, but will keep for now :- Technics SL-PJ25 (non working) because of its cool and exotic engineering : its linear pickup motor, and its robustness, built like a tank.- Thomson LD300 (non-working). Again luck of the draw. Found it cute and looked weird at the front. Looked more like an industrial or professional bit of kit than a consumer grade device... though I am sure it's consumer stuff... I guess. Upon receiving it, that impression was reinforced. Weights a ton despite it's small size, and the back of the unit tells you about the power and wavelength of the laser inside with a big yellow "caution" pictogram... I have yet to see a consumer player that tells you about the wave lenght of the laser inside...IIRC when I powered it up, didn't work and display was showing garbage. Popped the hood to have a quick look. Found that there was a massive crack/physical damage to the main board ! So obviously many traces must be broken... So this player is also a little challenge : can I manage to fix the circuit board ? Can I fix this player ?...Will give it a try. if I fail it will probably end up being scrapped like all the others...So now all I needed to be done with my CD player saga, was to button up the little Radiola so I don't have tons of parts spread all over the shelves, so I can frees some space and tidy things up in the lab.I did buy the big DI shift register chip and proto board to try and play with that, see if I could revive the LED display. But I gave up on that. Too much other stuff to do, I am moving on. So I ordered the turn-key replacement you pointed me to on Ebay. 37.5 Euros shipped. Just received it today.Well made. doesn't use the MM54XX big shift register though. Instead the guy used an 8 micro an Atmel AVR and a couple standard shift registers to assit it. He mus be programming them in situ because you can clearly se the foot print for the programming header...Soldered it, works just fine now, except for the discrete LED corresponding to the " REPEAT "button, which refused to light up. I have not bothered to probe around to see whether the diode had failed or if the module was at fault, because I had more pressing matters to deal with : tried playing a CD. Worked at first... for 10 seconds, then stopped. Works erratically. Sometimes detects teh CD, sometimes not... well you get the picture, same as before.I tried tweaking the laser trimmer but it was already to the max. I remember now... the player used to work only when the trimmer was at 99M. 100% would not work, 98% neither...so you just had to fart it to stop working.Now I remember I swapped swing arms with the Toshiba and we concluded it was not the swing arm at fault, IIRC.... so I tried swapping the swing arm from a CDM4/19 IIRC. Can't remember what was the outcome, was so long ago.Anyway this player doesn't work so I wasted 37.5 Euros on that display module. I am done with it, lost patience, moving on.Well I will keep it anyway, can't sell it like that, or for so little money it's not work it. Plus I grew fond of it anyway...So I think I will keep it for parts and am thinking of "upgrading", to a CD400 series, it's bigger brother, the one you've got and modified. IIRC I saw one that had a retractable keypad you can use to key in the track number you want and jump straight to it. I like this feature a lot as it's a pain otherwise to to " long jumps " so to speak. So one day might get one of these players.Anyway, thanks chaps for teaching me about CD players, learned a lot it was fun.Think I am done with trying to repair consumer stuff, it's waste of time and no money to be made. I woud still do it to fix my OWN stuff of course, or have a QUICK look at stuff friends bring me, but no more.For example I would like to find me a nice amp to go with my CD player. Following Shakal's advice I bough the cheapest broken half decent amp I could find, that bottom of the barrel Sony, for 15 Euros shipped... and it does the job. But now I would like something nicer. Better quality front panel/controls/plastics, more stuff inside : Sony is pretty much empty... just a single chip STK design... wold like one with a nice toroïdal transformer and lots of power output transistors....Don't know about brands models so might look for an old Yamaha "natural sound", and go from there. Of course a defective unit for 30 Euros max !Anyway. Gonna give that little Thomson a quick go then that will be the end of my journey in CD player land. Was fun, I don't regret it...