The Curse of the Old Music CD Player: Optics or Motors? - Page 1
Forum section: electronics / general

author: .o:0|O|0:o.
author_rank: Regular Contributor
timestamp: November 06, 2010, 08:12:44 am
content: I am about to open up several faulty music cd players (protable and small kitchen type stereos). They all seem to have a similar problem, the "signs and symptoms", as it were, are very similar, and all of the units just seemed to have died of old age; i.e., they never sustained any trauma or damage.When you put the CD in, the base motor rotates for a while and the other motor moves the laser diode up and down a couple of times before failing to establish a connection, and eventually it eventually gives up. Some units display "error", some display "no disk", some just turn off.While the CD is spinning, you can even skip through the tracks, but the system is never able to lock on to the selected track.In my opinion, there is nothing wrong with the control electronics or the processing side, but that the problem lies either with the motor(s) or with the optics.When repairing old equipment one of the first things I look at is the electrolytics near heat sources like power transistors. Nearly every TV I have fixed had failed due to a "dried out" cap.My understanding of electrolytic caps is that they have a mean life expectancy of 10-12 years, which makes capacitors a legitimate concern. Hence, sometimes people just recap an old board without too much investigating. However, I am not convinced it is the capacitors, because the problem seems to by the same for each unit (so then why that same capacitor when these devices are low powered and don't get that hot?).I have looked on the internet for some clues, but I didn't find anything of substance. It seams most people just throw away their old CD players and buy a new one (I use an MP3 anyway, so please don't suggest buying one as an answer). I could quite easily throw them in the bin and forget about them, but then I would still be left in ignorance about this problem.My reasoning tends towards the diode or phototransistor having deteriorated over time, so a disk is detected but the system effectively behaves like the CD is scratched or dirty (which is not the case having tried with multiple CDs - obviously).What is the best way of testing my theory (the diodes), without an oscilloscope? I have some old working CD-ROM drives and could possibly exchange the diodes, but I was wondering if there was a better way, since it may not be the diodes at all, maybe the motor or driver circuit.What do people think?.o:0|O|0:o.P.s. Someone once suggested that the expiry date is built into the system (like the Blade Runner movie), but I think that is unlikely, though technically possible.

author: Simon
author_rank: Unknown
timestamp: November 06, 2010, 08:34:48 am
content: it is the laser diode. I have been banging on about this for ages. I personally have made a choice to not buy any more CD players because they are deliberately made with weak laser diodes and they fail often after only 3 months. I replaced the cd drive in 2 of my dads HIFI systems, the drive cost half the cost of the whole system and took my up to 2 hours to replace making it unviable. My dad now uses a computer CD drive I rigged up for him plugged into an old amplifier, ok he canot skip tracks back and forward he can only play the whole cd but that is all he needs and the damn thing does not keep breaking,naturally the fault is those bastard manufacturers in china and yes they are bastards !. if I were the uk government I'd have all cd players examined before allowing import. they bang on about us being green with energy but don't have problem with millions of electronic devices going to landfill because they were made to fail.end of rant !

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 06, 2010, 09:00:28 am
content: one var resistor need to be tuned to get back to the "tune", the problem is, you need to find which. i'm suspecting some voltage reference has been off calibration value

author: qno
author_rank: Frequent Contributor
timestamp: November 06, 2010, 09:51:39 am
content: Have you tried to clean the laser lens with some alcohol?Check out the motor wires, sometimes the tiny plugs on the wire cannot handle the startup current of the motor anymore.If the logic does not get correct data within a few seconds it stops.If it works after some fumbling on the connector the contacts are burned.

author: Simon
author_rank: Unknown
timestamp: November 06, 2010, 10:24:56 am
content: cleaning the laser helps in the beginning but after that it is a permanent problem. generally the CD will spin but will not read the CD and will report no disk

author: Polossatik
author_rank: Frequent Contributor
timestamp: November 06, 2010, 10:46:30 am
content: I must say I agree with you, most cd players I seen seam to give up after a while and most of the time it seams like a alignment / focus problem - unable to find the disk. I hardly seen any cd player really going dead from other problems.Funny thing is that it's seams not limited to the "real cheapo" but any standard consumer grade player (including older music player that where relativly expensive in the early 90's) and that older CDROM drives (when those things still costed $$$) seams to be less affected (anecdotal evidence of course).Even those who still work seam to take longer after some years to "catch" the disk or don't play some (copied) disks anymore who worked before and work on other models (aldo that might be the writable cdrom deteriorating)In case you did not saw it yet In thehttp://www.repairfaq.org/sam/cdfaq.htmthere is a nice flow on how to start debugging.Alsohttp://www.repairfaq.org/sam/laserdio.htm#diolpv1bmight be of interest.Needless to say, watch out, even a cdrom laser can provoke eye damage!

author: Simon
author_rank: Unknown
timestamp: November 06, 2010, 10:55:13 am
content: home written disks are not as reflective as commercially written disks hence they are the first to not be read, the more you can tell the difference between the written and unwritten section of the disk the less reflective it is.

author: Polossatik
author_rank: Frequent Contributor
timestamp: November 06, 2010, 11:04:53 am
content: Quote from: Simon on November 06, 2010, 10:55:13 amThe point I try to made about that is that they seam to work less good with cdr's after while (assuming here you write a new cdR disk or verify the disk in other players - aka trying to rule out the disk) ,suggestingthe focusing ability of the cd player diminished after time .I do agree you cannot rule out the disk, every cdr type has a own reflective characteristic and cheapo CD's deteriorate really fast , but it's at least giving a hunch.

author: g***!
author_rank: Contributor
timestamp: November 06, 2010, 11:20:28 am
content: The only thing which has'nt been mentioned here, as is a very common source of disc reading errors, is the motor bearings. In the players with the small chinese motors, if you slowly, carefully tip the player on its side when the disc is spinning...the reading ability will dramatically improve with the cd player playing while the disc is in a vertical position. On a few occasions it has been necessary to replace both the laser, and the motor. (a complete mechanism can be cheaper) Hope this helps....

author: Simon
author_rank: Unknown
timestamp: November 06, 2010, 11:25:57 am
content: yes thats another possibility, if the disk wobbles because the motor bearing in knackered it will not be able to read it. I don't think the player looses the ability to focus, the lenses probably do not move but the laser does wear out and the bearings could wear out. either way it is the fault of the Chinese manufacturers that deliberately use poor quality parts.

author: orbiter
author_rank: Frequent Contributor
timestamp: November 06, 2010, 11:43:37 am
content: In a couple of Aiwa systems I've worked on I've seen mainly laser failure, but also on a couple of others I noticed that the ribbon cable that supplies power I signals to/from the laser/motor assy, have suffered broken wires within the shielding where it flexes.And as mentioned.. Do watch out for the laser!! I looked into one once by accident and a couple of days later wondered why I'd had a massive headache for two days

author: Simon
author_rank: Unknown
timestamp: November 06, 2010, 11:47:17 am
content: so basically general poor quality construction

author: orbiter
author_rank: Frequent Contributor
timestamp: November 06, 2010, 12:11:43 pm
content: Quote from: Simon on November 06, 2010, 11:47:17 amIt is. As you'll very rarely find problems like this with the likes of Rega, Leema or Naim type eqiupment.

author: Simon
author_rank: Unknown
timestamp: November 06, 2010, 12:20:55 pm
content: yea I even had a philips portable player fail in months

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 06, 2010, 01:12:25 pm
content: you people just dont get it! why dont you people go back and read carefully whats the OP said, is it disc problem? i onced use a "manual to fix ps2 cd reader" on my car lcd cd/dvd player. should i re-mention my previous post? i have a bunch of "scraped" cd/dvd players here, all the same exactly as the OP said. if you people havent fix one, why dont just you put "its just only my speculation" at the end of your every posts!cleaning laser lens? you just want to make it worst! and i've put my eyes right directly to the laser, and i can say the warning is both "bullshit" and "not bullshit"however... pollo's post is the most relevant.

author: g***!
author_rank: Contributor
timestamp: November 06, 2010, 02:31:14 pm
content: A few points I would like to add...Don't use alcohol on the lens, it may damage it...I simply use a cotton bud dampened with water....Weak lasers are almost impossible to diagnose correctly without specialized laser testing equipment...Quickest just to substitute a known good laser. Some people adjust the laser current, but in my experience the laser diode fails after a few months. I try to eliminate the motor first, if the bearings are ok, then check motor run up speed, if its too slow it gives a no disc error. As far as adjustments go, most cd players now dont have any, except for laser current. This is not specupation, I fix them for a living! And avoid looking into the laser...I only did that once!

author: cybergibbons
author_rank: Frequent Contributor
timestamp: November 06, 2010, 04:05:13 pm
content: Quote from: Simon on November 06, 2010, 11:25:57 amThe laser module has active focusing elements, and frequently these will suffer problems with alignment.

author: .o:0|O|0:o.
author_rank: Regular Contributor
timestamp: November 06, 2010, 04:14:01 pm
content: Thanks for your replies. I tend to play my CD collection in CD players so they tend to be original (who bothers making fake CDs with all the mp3 players around?). The reason for skipping tracks as soon as you press play is to access another sector on the disc - this works when there is a scratch over one particular song, but this is not the situation anymore. The lens over the diode does seem to move up and down as though it can't focus enough (the lens is clean, I used a no residue spray after an air duster).1) I am thinking that either the diode is not emitting enough light anymore2) or that the calibration for the focusing mechanism has drifted due to mechanical wearing (or precision component drift)3) or that the main motor does not spin fast enough anymore and lags behind the diode (a timing issue). The rotation seems balanced....Which you pretty much suggested in your posts. Regarding number (1) I was thinking that the manufacturers might be intentionally selecting low power diodes to stop them from being extracted and misused, and that they operate them at the top of their specification to compensate, which leads to the same problem for every player I have owned.I am about to place a CD-ROM diode into the music player. It was a bugger to extract, but it is fairly similar in size. I imagine that the CD-ROM diodes have to be of superior quality in order to read at much greater speeds than the music players. Hopefully the player will be able to supply enough current to the new diode.If the new diode doesn't switch on enough or at all would there be any way of accessing the batteries for a little added power through a simple resistor capacitor circuit? It appears that the diode stays on a constant current while in operation (no pulsing or anything complicated) , or would the current control be flexible enough as it is..o:0|O|0:o.P.s. Nearly all my discmans have been Sonys, because as a child when I took things apart I realised that Sony used SMT while everyone else was using poorly soldered crooked components on cheap resin boards. I had very little knowledge at the time but Sony always seemed to be a few years ahead.

author: cybergibbons
author_rank: Frequent Contributor
timestamp: November 06, 2010, 04:34:07 pm
content: I love the totally uninformed ranting about product design and Chinese manufacturers again.No one in their right mind imports anything into the UK that will not last 12 months or more. You can just walk right back into the shop and insist they repair, replace or refund during this time. No shop wants to replace a product 4 times, as there is no way that a CD player that lasts 12 months would cost 4 times more to manufacture than one that lasts 3 months.If you throw away something if it breaks in 3 months, you aren't taking advantage of consumer protection laws, and the retailers and manufacturers aren't punished for poor quality goods. This is your own fault.If you are fed up with replacing your CD player frequently, then simply spend more money in the first place. Naim players are built and priced for idiots with more money than sense.Everything in this world is produced to a price point. Consumers demand cheap products, and they also frequently upgrade their products. If it was found that a CD player is replaced every 3 years, why design the laser to last longer than that? They have been doing this with car engines for a long time now - take the MA10 engine used in Nissan Micras. Upwards of 90% of these will die between 115-130k miles. This is because they designed the engine to a price point, and did it very well. They could have spent twice as much on the engine to get 200k miles out of it, but by that point, no one wants the rest of the car.I've worked on the analysis of the lifetime of a complex telecommunications system. To meet specs, there had to be a high chance (it was tightly defined, but not worth going into it here) that each system would run for 5 years without a hardware failure. We didn't want to make the system more expensive than it needed to be, so approached the task from several angles:* How cheap can the components, parts and processes be before MTBF suffers? We were surprised at the minimal gains made by more expensive parts, especially with the semiconductors and mechanicals.* If we theoretically redesigned the system to have less solder joints, resistors, fewer backplane connectors, but fundamentally the same,would this be be a cheaper solution that more expensive parts and processes?* If the system was redesigned to have more redundancy and fallbacks, would this be better than any of the above solutions?* If testing was improved so that the systems going out were more reliable, would this be cheaper?A lot of thought went into it, and I am sure a lot of thought goes into a CD player or iPod.

author: JohnS_AZ
author_rank: Frequent Contributor
timestamp: November 06, 2010, 04:56:46 pm
content: cybergibbons touched on a point that most people not involved in manufacturing ever really understand.Most everyone thinks of quality in terms of finish, performance, and longevity.In manufacturing terms 'quality' only has one definition: "Meets designed requirements"If a product doesn't meet requirements, it's a failure.If a product exceeds requirements, it's most often pointing at waste and excess in manufacturing, also a failure.The thing is people tend to think of quality in terms of absolute metrics and never factor in cost.Fluke manufactures DMMs that cost north of $400, and they are high quality.Chinese manufacture DMMs that cost $4, and factoring for cost, they ARE high quality as well.It's as if people are saying the quality of their Ford car is terrible because it doesn't go as fast as a Ferrari.It's been said a billion times ... "You get precisely what you pay for."

author: Unknown
author_rank: Unknown
timestamp: November 06, 2010, 05:17:45 pm
content: Quote from: JohnS_AZ on November 06, 2010, 04:56:46 pmIf published specifications (marketing) were closer to the internal design requirements, this would be less of an issue. And that's often an issue with those $4 products. For the buyer, if a DMM is sold as being able to measure up to 1000VDC, and dies with 300VDC, that's bad quality, even if it was only designed to look good on the shelf and not actually be used. Same with a DMM with 0.3% accuracy that's actually 0.5% off. If manufacturers want to use design requirements as justification, they should publish them. If you print on the box that the TV is designed to last three months, you won't get as many complaints if it dies after that time.

author: .o:0|O|0:o.
author_rank: Regular Contributor
timestamp: November 06, 2010, 05:34:53 pm
content: When portable CD players were popular, I used to go for the Sony models, which were more expensive. They had more features, looked better designed, felt better and they actually were better designed, if you opened them up. They were way ahead of AIWA or Panasonic or even Philips in using SMT in their walkmans and discmans, making them lighter more compact and with better battery life (even double that of competitors at the time -- now I am sure it is no longer as clear as that).The point of the original post should not be missed: all portable music cd players seem to fail in the way explained, even the expensive ones. Hi-Fi CDs tend to last longer, but then I tend to listen through portable gear far more.When I talk about quality of the diode, I am not ranting. The CD-ROM diode and motors obviously have to meet higher requirements.(Your point is not always true either; the same item can sell at very different prices when people are not completely informed and though better built, CD-ROM players are often cheaper than music cd players. Company reputations are buily on offering good quality at reasonable prices and those that can't provide both don't do well over the long term. The cost of the product depends on many fctors (labour, expertise, etc.). Just because something passes a standard to enter the UK, doesn't make it of high quality by default. All sorts of crap has made it to the UK.)I am talking about old products that were good at the time. When a cheap piece of crap brakes it is no surprise!I don't mind if people want to rant as well, but any technical advice would be appreciated.Thanks in advance,.o:0|O|0:o.

author: orbiter
author_rank: Frequent Contributor
timestamp: November 06, 2010, 06:24:45 pm
content: Quote from: shafri on November 06, 2010, 01:12:25 pmNot a very nice way to address people if I may say so.

author: .o:0|O|0:o.
author_rank: Regular Contributor
timestamp: November 06, 2010, 11:58:44 pm
content: ...Anyway, I managed to switch the diode in the end - very fiddly and only for days you are feeling very patient... Tomorrow I will close it up and see if it worked. Its a shame these diodes don't have part no.s printed on them as it would be interesting to know what the power rating differences are.EDIT: I should have tested it while it was still in the unit. Nevermind....No lets see if this thing works!.o:0|O|0:o.

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 07, 2010, 01:06:26 am
content: Quote from: orbiter on November 06, 2010, 06:24:45 pmmaybe i have a bad dream the other night, sorry if it hurts.Quote from: JohnS_AZ on November 06, 2010, 04:56:46 pmi learnt this in U! i never practice it but i'm very well understand it. Its mechanical thing, but i think its very the same with any production incl EE. If you want longer lasting, you put more "metal" in it, when you want to set it to fail at some period of time, "reduce" the metal, hence reducing the "price".ps: toys nowadays... dont use metal anymore!

author: sonicj
author_rank: Frequent Contributor
timestamp: November 07, 2010, 05:37:25 am
content: i recently repaired the superdrive in my macbook pro. it started to have problems initially only when writing to the disc. eventually it would neither read nor write to dvd nor cd. disassembled 1/2 of the computer, opened up the drive, cleaned the lens with zeiss wipes and a loupe (normally would have used a denatured alcohol that doesn't leave residue or everclear, but thats all i had at the moment), further disassembled the unit to gain access to the rails, cleaned old lube off with kimwipes & cotton swabs, relubed rails with triflow synthetic grease and a toothpick, reassembled. everything works as new!Quote from: shafri on November 06, 2010, 01:12:25 pmthis is very, very bad idea! just because the radiation emitted is not within the visible light spectrum or does not cause immediate pain or discomfort does not mean it is safe to look at.-sj

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 07, 2010, 07:30:15 am
content: Quote from: sonicj on November 07, 2010, 05:37:25 ami guess you worked in "sahara". i never had dust issue. use a blower is the safest bet. usually a lil bit of small dusts wont affect the performance, i guess the others suggestion about the laser diode is the most affecting part of the operation.i said it both bull and not coz a quick look wont damage your eye, but overdoing it could. the light is irritating tough. just did it once, just to try... and to tell the world. i'm still ok here with both eyes workingand IIRC there is no discomfort or headache afterward, but for the young player, my suggestion is to just follow the warning. there are other more brilliant method to test the laser.

author: sonicj
author_rank: Frequent Contributor
timestamp: November 08, 2010, 12:31:45 pm
content: Quote from: shafri on November 07, 2010, 07:30:15 amthis form of failure is common for apple slot-load drives.

author: .o:0|O|0:o.
author_rank: Regular Contributor
timestamp: November 09, 2010, 04:28:52 pm
content: These laser modules are incredibly fragile, and very easy to damage irreversibly. However, in comparison to the cheaper modules, those found in CD-ROM players are built like tanks (see pics).I pretty much determined right from the start that it wasn't a dust issue from the behaviour of the system -- and apparently, from one of the repair faqs posted (thanks for that), the light emitted isn't affected that much by the amounts of dust that might enter the unit over time. In fact, it is interesting to note that the laser diode isn't actually situated directly under the collimating lens but hidden away under to a side at at 90 degree angle, so that the beam is reflected off an inclined reflective strip through the lens. The lens is raised and lowered using a delicate solenoid based mechanism.The problem I had was that the diode had failed. I don't know what the rating was for this particular diode, but they seem to be rated at far lower than your typical LED, at around 7 mA, perhaps someone can correct me if I am wrong. I didn't want to risk damaging the good laser by adjusting the trimmer which I imagine is there to limit current, so I "simply" (it wasn't) transplanted the better diode into the circuit ...and it works!I don't know if anyone else has noticed this, but some CD players use light on the red spectrum and others use blue. Since CDs are made to a certain specification I would imagine that both are equally effective, but that perhaps the photodiode might have to be matched according to the wave~length. However, blue photon's are more energertic than red ones so I was wondering if there would be any advantages to using blue over red.....o:0|O|0:o.

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 09, 2010, 05:23:17 pm
content: Quote from: .o:0|O|0:o. on November 09, 2010, 04:28:52 pminitially its already been damaged while u open it, so what do u got to lose by adjusting the trimmer? and u got the hassle of dissambling the diode unit.good info though, now i know, replacing diode could fix it... how do you know which diode replacement is good/compatible for the unit? i have many cd/dvd player/rom here, each unit got different laser unit, how to see the diode spec?

author: .o:0|O|0:o.
author_rank: Regular Contributor
timestamp: November 09, 2010, 07:32:07 pm
content: Shafri:By tampering with the trimmer with the faulty diode still inserted I wouldn't have learned much more if anything and it would have added further uncertainty if, after inserting the functioning diode, it didn't work.Unless there is a part number and associated data sheet, the only way of knowing for sure that you have a suitable replacement (assuming the two diodes are uknown to you) is through measurement. The problem with measuring forward current and associated output is that you may damage the device....The metal casing of the CDROM module acts as a heatsink for the diode. The plastic module from the crappy stereo system does not serve that purpose and as a result you have a dead diode after far less use. Unfortunately I couldn't swap the entire module, so I will probably end up with another dead diode eventually..o:0|O|0:o.

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 09, 2010, 11:37:25 pm
content: i mean how do you get a diode from another model to be working on another model? are they the same part number? (the diode)?

author: sonicj
author_rank: Frequent Contributor
timestamp: November 10, 2010, 04:31:04 am
content: Quote from: shafri on November 09, 2010, 11:37:25 pmscrewdriver, spudger, dremel, loupe, skill, luck, epoxysometimes a electronic device has to die in order for others to live on. common computer drives are rarely "worth" the repair effort. regardless of the outcome, taking them apart to learn to how they work gives you the knowledge, skills and confidence to take on repair challenges of more valuable devices.-sj

author: .o:0|O|0:o.
author_rank: Regular Contributor
timestamp: November 10, 2010, 10:14:48 am
content: Quote from: sonicj on November 10, 2010, 04:31:04 amI have destroyed CDROMs and CD players before so I had the feeling it would be possible to effect an easy switch between the two parts. Luckily there was no epoxy involved and I was able to ease the diode out with a small screwdriver. The diodes were of similar dimensions, which made it all a lot simpler. The hardest part was desoldering and resoldering the pins from the flexi and then reassembling the stereo.The stereo was built so poorly inside that it is probably not a design to go by, but I noticed that instead of using an integrated full-wave/ bridge rectifier, they used a small board with discrete components: 4 diodes, 1 electrolytic and 4 ceramics. I have seen these modules before, but I would have thought it would be cheaper to use an integrated rectifier. Furthermore, they used 4 ceramics at that stage, considering the cheap construction (I have a Philips amp that uses something similar, but only requires 1 ceramic between Vout and ground). It looked like they bought a bunch of different modules from different places, wired them together and jammed everything into a deceptively charming little enclosure. Not designed to last, which is a shame because most individual components tend to have a good ten years in them if used properly. I wonder how many components they used unnecessarily.I guess the reason people don't return the products 4 times within a year is because they last long enough for people to discard the proof of purchase and are so cheap in the first place that it is hardly worth the hassle six months to a year down the line. I once bought a pair of Chinese in-the-ear type ear phones for a few pounds. I didn't expect the sound to be great, but I was a bit surprised when picking them up a few months later the foam/sponge which had gone hard crumbled between my fingers..o:0|O|0:o.

author: Time
author_rank: Frequent Contributor
timestamp: November 10, 2010, 05:23:09 pm
content: A smaller wavelength will let you resolve smaller images. This is due to optical effects like diffraction which impact focusing spot size. So naturally a blue laser can read much more tightly packed data off a disc which in the end allows for more information per disc. Photon energy is proportional to wavelength so I guess it isn't incorrect to say its the energy that gives you a better resolution. Its more accurate to say wavelength.Do not stare into laser diodes. Especially the ones from optical drives. Those warnings are not bullshit and if you think so keep staring into them and report back.