hybridfree/eevblog-posts huggingface dataset:
Case 87638864 instrument cluster - Page 1
Forum section: electronics / repair

author: diag7919
author_rank: Contributor
timestamp: February 07, 2024, 04:17:27 pm
content: I need some help.. I have 2 components I can't identify, first is the SOT457? Q5 (transistor?) With markings 9V 7.8... I also have a LCD module, it's 28p and it has just 8 thick bars in the display.. I tried to read the code etched on the end of the glass and the best possible match is M4183 N32002, although the last set of numbers is very tricky to read.. this is out of a skid steer made by Case, it's sealed, was sealed, which broke the LCD but other than that it's fairly dead, just 2 lights come on, nothing elsewhere... Oh, I do also have a 8p device which is etched MXRE L0DA, no idea what that's doing.. any help would be very much appreciated.. most would see it's sealed and suggest just replacing it but I like a challenge.. might have bitten off more than I can chew..

author: fzabkar
author_rank: Super Contributor
timestamp: February 07, 2024, 04:41:21 pm
content: XN04211, Panasonic, NPN dual transistors, 50V, 100mA, 300mW, marking 9V, SOT23-6:https://media.digikey.com/pdf/Data%20Sheets/Panasonic%20Semiconductors%20ICs%20PDFs/XN04211_Rev_Nov_2011.pdfhttp://markingcodes.com/search/c/9vLP2951ACMM, Texas Instruments / National Semiconductor, Adjustable Micropower Voltage Regulator, 2.3V - 30Vin, marking L0DA, VSSOP-8:https://www.ti.com/lit/gpn/LP2951-Nhttps://www.alibaba.com/product-detail/LP2951ACMM-LP2951ACMMX-NOPB-L0DA-LODA-MSOP_1600086122414.html(photo)http://markingcodes.com/search/c/L0DA

author: diag7919
author_rank: Contributor
timestamp: February 08, 2024, 08:41:46 pm
content: Fantastic, thanks for reply.. made some progress, no clock, crystal?, hence dead uP.. no luck with the LCD mind, been searching on/off all day.. might be a custom part?.. think my solution, replace it with a LED bar graph (guts out of a eBay fuel level Meter)
Casio-CTK-810, which potentiometer is this? - Page 1
Forum section: electronics / repair

author: htm
author_rank: Regular Contributor
timestamp: September 21, 2021, 11:39:52 am
content: HiThe potentiometer is broken on a friends music keyboard.He would like to know the part number and rating for replacement.He couldn't find any specs online.Can you help us find it?Some numbers i got from him. not sure where they were located;69308726RK09K12C0D0WEVM3SSX50B53Pics of the potentiometerCheers

author: htm
author_rank: Regular Contributor
timestamp: September 27, 2021, 06:45:08 pm
content: Thanks for the 118 views.i'm replying myself, to nudge this question up once, just once. Hoping for an idea where to start

author: tunk
author_rank: Super Contributor
timestamp: September 27, 2021, 07:04:13 pm
content: It might help if you post some resistance values, maybe start, middle and end.

author: fzabkar
author_rank: Super Contributor
timestamp: September 27, 2021, 07:08:06 pm
content: I found it in a service manual for the Casio PX-700. Unfortunately there are no resistance values.https://elektrotanya.com/casio_px_700.pdf/download.html(page 20)

author: SeanB
author_rank: Super Contributor
timestamp: September 27, 2021, 08:10:11 pm
content: Are you sure the pot is faulty, and not just the obvious dry joints on the solder to the ribbon cable, which is probably the reason the push button function is intermittent or not working at all.

author: Audiorepair
author_rank: Frequent Contributor
timestamp: September 27, 2021, 08:14:48 pm
content: It's a stereo volume pot, the resistance value is not likely to be particularly critical.10k Log would probably do fine.Trouble is, you'll struggle to find that 5-pin footprint off the shelf.In fact I'd go as far as to say you won't.Casio do actually sell spares. Or at least they did the last time I bought pots from them.Or you could try and hard wire any stereo pot in there if you could find a way of attaching it to the panel.

author: floobydust
author_rank: Super Contributor
timestamp: September 27, 2021, 09:44:14 pm
content: It would be an AlpsRK09Kseries part, Panasonic also made them, the 9mm potentiometer.Harder to find with a switch but they are out there. Many chinese knockoffs as well.

author: andy3055
author_rank: Super Contributor
timestamp: September 27, 2021, 10:23:24 pm
content: Remove it from the board and follow the diagram to measure the individual sections. Pins 1 and 5 should be one and pins 1 and 4 should be the other. If they are both equal, you should be able to find a stereo or dual pot with the same values. However you have to figure out if they are linear or log. If the values are different, you have a problem!Like someone else mentioned, why do you think this is faulty anyway? It may need cleaning if at all, which is easy once it is off the board.

author: fzabkar
author_rank: Super Contributor
timestamp: September 27, 2021, 10:36:03 pm
content: https://au.mouser.com/datasheet/2/15/rk09k-2018422.pdf(datasheet)https://au.mouser.com/ProductDetail/Alps-Alpine/RK09K12C0D0U?qs=%2Fha2pyFaduhaKTkn6BKskFmb846wvFCzmvLGdv3CfwJsT9%252BlBDfPwg%3D%3D(RK09K12C0D0U, similar?)
Casio electronic calculator - Page 1
Forum section: electronics / repair

author: 001
author_rank: Super Contributor
timestamp: August 10, 2019, 03:04:22 pm
content: HiMy main gear is Casio FX-991ES ELECTRONIC calculatorDisplay contrast is adjustable by menuBut digits looks blue at any contrast value, not blackCan I replase polariser etc to get black digits?

author: Kean
author_rank: Unknown
timestamp: August 10, 2019, 03:12:53 pm
content: How does this belong in Test Equipment category?

author: 001
author_rank: Super Contributor
timestamp: August 10, 2019, 03:13:47 pm
content: Quote from: Kean on August 10, 2019, 03:12:53 pmBecouse it is my test equipment

author: Gyro
author_rank: Super Contributor
timestamp: August 10, 2019, 07:53:01 pm
content: Almost certainly not, without destroying it.

author: benj38
author_rank: Frequent Contributor
timestamp: August 12, 2019, 02:35:01 pm
content: I have successfully replaced LCD polarizing films in the past (though not on this specific calculator).The good thing is that you can easily tell if it is indeed the polarizing film by simply placing a good polarizing film between your eyes and the LCD and observe if the contrast improves. Note that you should try this with the film rotated at different angles.One can usually find replacement polarizing films for cellphones very cheaply on eBay. One such film would probably be several times bigger than the calculator LCD, thus allowing you to try again if you mess it up the first time.The polarizing film has one side coated with glue, and if done carefully it can be applied by hand to a small display, such as one used in a DMM or calculator, without introducing any air-bubbles. Removing the old polarizer can be easily done with the help of a hot-air gun and a razor blade. Clean the leftover glue with isopropyl alcohol.Note that the new polarizing film comes with an almost invisible protective film that should be removed when done (usually the protecting film can be identified by some printing on its edges: e.g., two thin lines) .The usual disclaimer follows: try it at your own risk, You may do more harm than good if you are not careful, or if your particular LCD turns out to be the exception.
Casio FX-7500G graphics calculator repair - Page 1
Forum section: electronics / repair

author: Falowod_Jerzy
author_rank: Newbie
timestamp: November 29, 2021, 07:41:43 pm
content: Hi. I’m trying to repair my Casio fx-7500g graphics calculator, which suffered a drop while back and now part of display is not working properly. It can still do some calculations, so I think processor and memory is still good. I still tried putting on new solder to theirs pins, but it did not help to solve the issue.I’ve checked ribbon connection between two boards, because it was the most suspicious for me due to broken hinge which I’ve already glued together. It is over EPROM chip labelled uPD27C256AG and under black sticker. It has pins labelled from 1 to 31. I’ve made a measurement and most of them has resistance of about 30 Ohms, but couple last have somewhere around 50 Ohms. So I think that connection is good.While I was touching board to see if it changes anything, I discovered that if I put my finger somewhere around capacitors C104, C30Ps and blue oscillator, some more lines starts to appear (once I managed to get whole display working for a second), but calculator appears to crash. So I redone those connections as well. It also did not help. I checked oscillator with my oscilloscope (which is 20yr old and probably out of calibration) and if I measured it correctly it has 20MHz output signal, while datasheet states that it should have 2MHz. Also I desoldered one C30P capacitor for measurements and it showed 37pF, so it put it back because it looks good to me and i do not have a raplecement.What I should try next? Or maybe this osclillator is the problem? I’m out of ideas.

author: andy2000
author_rank: Frequent Contributor
timestamp: November 29, 2021, 07:52:08 pm
content: Based on the diagonal line running across the screen, it's clear that the display is cracked.

author: Falowod_Jerzy
author_rank: Newbie
timestamp: November 29, 2021, 08:07:16 pm
content: Quote from: andy2000 on November 29, 2021, 07:52:08 pmI don't think it is crakced, I can get vertical lines to show up on the blank portion of the screen, while touching pcb somewhere around the oscillator and capacitors. And also I think that there wouldn't be any horizontal lines below that diagonal line if it was cracked. Maybe it's broken, but i don't think that sympoms of that are clear.
Casio fx-82TL display weird problem. - Page 1
Forum section: electronics / repair

author: ktulu
author_rank: Regular Contributor
timestamp: August 06, 2025, 08:45:27 am
content: Hello.I picked from trash a Casio fx-82TL scientific calculator. Had all the case screws missing.Inside looks mint. Absolutely no visible faults, corrosion or such on either side of the PCB.To my surprise when I inserted a battery it did nothing. At first glance.After some measurements, the calculator probably works. Current draw is normal, more complex calculations take longer time to execute.However the display stays blank.Connecting the scope to LCD lines, the waveforms look all distorted. (1-3.mp4)The lower part of the common/backplane and segment waveforms are brocken up and pulsate in 50Hz rythm.When I put my fingers on the display tracks (all have solder mask) the hum hugely increase. (4.mp4)I repeated this on one of my other/different Casios, and it has no influence at all.This looks to me like the reference point of the bias voltage generator circuitry is floating?There are 7 100nF caps. Replacing them changed nothing.Both sides of C2 measure a normal square wave. (C2-1.jpg, C2-2.jpg)All waveforms are referenced to negative rail.I have never encountered such a fault on any LCD device ever.It would be a big help if somebody could take some scope measurements on his/her fx-82TL. I'm especially interested on both sides of C1-C7.

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: August 09, 2025, 12:10:28 am
content: Many times the problem is the main IC connections under the blob of epoxy.The way it is built is why they fail. Sometimes pressure will work for a while.Jeff

author: ktulu
author_rank: Regular Contributor
timestamp: August 10, 2025, 02:26:54 pm
content: Unfortunately pressure doesn't help. I tried heating and freezing the blob before, without any change.When I touch one end of the LCD ribbon, and I have the ground lead of my scope connected to the negative battery terminal, i get some pulsating ghosty image and I'm able to see the first few characters partially.
Casio FZ sampler - EL backlight problem - Page 1
Forum section: electronics / repair

author: Peacefrog
author_rank: Contributor
timestamp: July 04, 2023, 06:43:25 pm
content: I am repairing a power board in a Casio FZ-20M sampler - and while I've got the 5V, 12V, and 15V rails up and working the EL backlight doesn't seem to be doing what I'd expect.The schematic is attached - the circuit is powered by the 5V rail, and I'd expect it to be putting out 90V AC - but it actually measures 140Hz 9V AC without a load. I've tested the caps, resistors, and transistors and all seems in range.I wonder if I'm missing something, as I'm not too familiar with how the circuit works - could anyone help me diagnose? In particular, I'm wondering if this needs a load in order to work correctly. Thanks!

author: RoGeorge
author_rank: Super Contributor
timestamp: July 05, 2023, 06:20:50 am
content: In the collector of the 2SD400F should be stable DC voltage. If yes, check all 5 components between B, E and pin 7 of the transformer, including the transistor. Together they make an oscillator. The worst would be to have short-circuit turns in the transformer, but let's hope not. I would check or replace the 5 components first.

author: fzabkar
author_rank: Super Contributor
timestamp: July 08, 2023, 05:29:03 am
content: I would test the transformer out-of-circuit. Apply a sinusoidal input between pins 2 & 3 and measure the output between pins 2 & 5. (Of course, do the easy stuff first.)

author: Peacefrog
author_rank: Contributor
timestamp: July 11, 2023, 03:03:47 pm
content: I was able to find a spare scrap board with the same inverter, and it's fired right up after transplanting in the transformer.The one problem - *without* load (which I understand is not advisable, so I haven't been leaving it powered this way long), I measure ~240V AC and 1.4kHz - am I safe to connect the backlight, in the belief that this will drop? I'd expect it more in the ~120V AC / 160Hz(?) range.
Cat5 Video Rx Unit - Page 1
Forum section: electronics / repair

author: olliez0r
author_rank: Newbie
timestamp: August 17, 2020, 01:43:45 pm
content: Hi guys,Long time reader first time poster etc etc...My knowledge is pretty sparse but I'm confident when armed with a small amount of knowledgeGot a UTP video Tx/Rx (not IP/switched) set at work for sending VGA over large distances.Had two of the Rx units fail - they're supposed to receive power over the UTP cable (direct from the Tx unit), but can take 12v separately; have tried and the LED doesn't light and video signal doesn't work under either condition.I'd like to think it's as simple as a fuse on the board, but there's some components that I'm not sure how to identify.Picture attached - the component in the bottom right does not have continuity - could this be it? The (assuming) fuse under the DC jack is fine, but I wouldn't expect this to have any impact on the standard power input anyway.Any advice is appreciated; work can't afford to buy replacements for these as they're surprisingly expensive.Cheers,Ollie

author: macboy
author_rank: Super Contributor
timestamp: August 18, 2020, 04:05:11 pm
content: The component circled in red is a fuse. It should read at most a few ohms, in either direction.The component circled in green is a reverse protection diode. If power is connected backwards, then this short circuits the power supply (preventing reverse voltage reaching the devices) and blows the fuse. In one direction, this diode should measure something around 600 mV (+/- 200 mV) using the diode test of your multimeter. In the other direction it must measure as open. If shows continuity in both directions, it is bad. If it doesn't measure good (~ 0.6 V) in the forward direction, it is bad.
Cause of distortion by harmonics - Page 1
Forum section: electronics / repair

author: notadave
author_rank: Contributor
timestamp: September 12, 2019, 11:31:25 am
content: Is there a way to tell the cause of distortion from the harmonics?I looked at a bad (just crap straight out of the factory) Chinese preamp and found that it had little 2. and 3. harmonics but real bad 4.Without having had opened the case, I was baffled. I had seen 3. and other odd harmonics but never 4.That raised the question whether there are some wise rules from experience or theory as to what to look for as the cause.Usually you can not see anything wrong on the scope so you have to go by the spectrum alone.I am looking for something like:strongest harmonic:likely cause:Firstrelax this is what you wantedSecondsaturation towards one polarityThirdsymmetric limitingForthasymmetric supplyFifthsame as 3.EvenasymmetryOddsymmetric limitingThere should be a list of things to check/look for.

author: PKTKS
author_rank: Super Contributor
timestamp: September 12, 2019, 11:36:15 am
content: If your audio is using these "new" things with SMPS or class-D gizmos.Forget it. They are just noisy oscillators producing vast amount of harmonics.Any audio forum will confirm that TUBES and real LINEAR good PSUswill do your audio the way it should be.But these devices are long gone considered vintage...go figure if high-fi devices are vintage now...Paul

author: notadave
author_rank: Contributor
timestamp: September 15, 2019, 01:01:39 pm
content: Quote from: notadave on September 12, 2019, 11:31:25 amTurns out, that in this case the input was a NPN with the load at the collector (Common emitter), that had a very small base current and low resistor at the base. A tiny signal was enough to turn the BJT off.The supply was not the cause.The simplest fix was not to raise the OP current but to increase the input resistance.
CCD/CMOS CAMERA borescope - milwaukee m12 m-spector - Page 1
Forum section: electronics / repair

author: shockpoint
author_rank: Contributor
timestamp: November 15, 2024, 01:37:55 pm
content: Hi,I am repairing a borescope - the 8 year old M12 M spector from milwaukeeAfter taking the camera end apart, I found that there are 4 wires, typical of a borescope:- video- 3.3 volts- GND- LEDI terminated the connections again and tested itWhile it works, the camera sensor is ridiculously out of focus.The camera sensor is one of those PCB modules that has the grooves on the lens that allow you to twist it open to access the CMOS/CCD panelI tried cleaning it with alcoholApart from being out of focus, there doesnt seem to be any static or noise so i dont think its because of lack of shielding of the video wire during the testing phaseDoes anyone have any ideas? Ive no idea how these cmos work so I don’t know where to start looking to make the image more in focus. It recognises color, light and dark but its like really short sighted for lack of a better descriptionThank you
CD Drive Repair HPC-3LX - Page 1
Forum section: electronics / repair

author: JoergR
author_rank: Contributor
timestamp: October 08, 2022, 08:53:28 pm
content: Hi all,I'm trying to repair my inlaws Sharp XL-T300H stereo - a compact thing of only emotional value. It appears the CD Pickup is broken. CDs were turning and read, but the audio was distorted. Audio on FM works fine, so I think it's not a problem with the audio system itself.The laser pickup is a HPC-3LX 20N which appears to be a standard part. I got a replacement part HPC-3LX30N (note the difference) from eBay that looks identical to the part I removed from the unit. Upon putting it in, CDs would not even start to turn anymore and the display shows "No CD"So now I have two questions forum members may be able to answer:1) Does anyone know if an HPC-3LX 30N should work in place of the original HPC-3LX 20N?2) If it should work, how can I test conclusively, if the replacement part I got is actually working?Thanks a lot for any help.Best,Joerg

author: fzabkar
author_rank: Super Contributor
timestamp: October 08, 2022, 10:37:06 pm
content: Laser assemblies are shipped with a solder blob to protect them against ESD. You need to desolder this blob before installation.

author: JoergR
author_rank: Contributor
timestamp: October 09, 2022, 06:26:42 pm
content: Thanks for the reply, that is interesting. Could you be more specific as to where such a solder blob is to be found / removed? I've attached an image of the pick up unit I removed and the new one looks identical - also on the solder side - the only differnence being the 30N instead of the 20N on the sticker.

author: fzabkar
author_rank: Super Contributor
timestamp: October 09, 2022, 06:39:50 pm
content: I don't know if all laser pickups are shipped with a blob these days, but here is one example:

author: JoergR
author_rank: Contributor
timestamp: October 11, 2022, 08:18:41 pm
content: Thanks so much - one really needs to know what one is looking for to actually see it!Removing the blob and the unit works again.Do you know why these blobs are there? I suppose they shorten the laser diode. Are there any other typical components that feature this kind of protection?Thanks so much, my inlaws will be thrilled ;-)

author: fzabkar
author_rank: Super Contributor
timestamp: October 11, 2022, 08:52:50 pm
content: I don't recall seeing these blobs in other scenarios, but I haven't seen everything. :-)I assume that the blobs straddle the laser's terminals, but I've never examined them closely. All I know for certain is that the blobs protect against ESD during shipping and handling.

author: JoergR
author_rank: Contributor
timestamp: October 12, 2022, 03:44:11 pm
content: Well, still some mysteries to explore. Thanks again anyhow!
CD player analogue servo circuits - Page 1
Forum section: electronics / repair

author: laureng
author_rank: Newbie
timestamp: July 28, 2025, 05:37:52 am
content: Is there anyone here with experience with analogue servo circuits?Attached is part of a tracking circuit from an 80's era CD player (Yamaha CD-3). The tracking error signal from the laser pickup is passed through op-amp IC202B to driver IC203B which goes back to the pickup to drive the tracking coils.What I don't get is the mess of transistors TR207, 208, 209 and 210. TR207 can be driven by the servo IC's "tracking off" (TROF) output, which I suppose shunts the tracking error signal to ground and effectively switches off the tracking coils (straightforward). But TR208, 209 and 210 look like a kind of feedback with the involvement of 10uF cap C208. What does that do?Anyway, just trying to understand these schematics better so I can diagnose and repair these old machines. This one has a good feed motor and driver but the sled is reluctant to move, which I'm wondering is due to high leakage current in old electrolytics (in another part of the schematic - not shown).Cheers!

author: xavier60
author_rank: Super Contributor
timestamp: July 28, 2025, 01:37:02 pm
content: They limit the DCV applied to the tracking coil to about 1.2V, plus or minus. Positive voltage turns on TR210. Negative voltage turns on TR209.Either of which will turn on TR208 which in turn, turns on TR207, reducing input voltage to the opamp.Edit: A likely reason for this would be protect the tracking coil from excessive heating in case of a sled-feed stall.
CD player VFD fault symptomatic of other problems? - Page 1
Forum section: electronics / repair

author: Noidzoid
author_rank: Regular Contributor
timestamp: March 30, 2020, 02:09:12 pm
content: CD Player - Musical Fidelity X-RayThis is the problem on the surface, could this be the driver for the VFD causing a problem?If so, is it possible that whatever the problem could be linked to the unpredictable jumping the player does when playing a CD?The KSS-240A assembly has been replaced (which made it behave better but not cured).The rails and guides have been dismantled, cleaned, re-greased and reassembled.Or is it more likely that these two faults are unlinked.Many thanks for any interest taken

author: TheMG
author_rank: Frequent Contributor
timestamp: March 31, 2020, 06:31:07 pm
content: It's like the correct voltage is not being applied to the grids in the VFD to keep the segments that are supposed to be off, fully off. VFDs are multiplexed in sections and function much like a vacuum tube.This could be a driver issue but since you say there are other faults with the unit, I would suspect likely a power supply problem. Check all power supply voltages to see if they are correct, and also measure the amount of ripple on each output. Probably some bad capacitors causing a high ripple and voltages out of tolerance.

author: Noidzoid
author_rank: Regular Contributor
timestamp: March 31, 2020, 07:38:06 pm
content: Thanks TheMG, I'll start thereI think I have already asked this but it can't hurt to ask again. Does anyone know where I can find aservicemanual for the X-Ray?

author: AndyC_772
author_rank: Super Contributor
timestamp: April 01, 2020, 07:32:51 am
content: I had a very similar problem on a DAT machine. Turned out to be a failed Zener diode in the power supply, which meant that two voltages which were supposed to be different, weren't.
CDJ-3000/UXJCB6 Jog Wheel Rotation Not Detected - Page 1
Forum section: electronics / repair

author: kylec
author_rank: Newbie
timestamp: October 12, 2025, 12:51:36 am
content: Two CDJ-3000/UXJCB6 were tested and fully functional prior to open/closing to be cleaned. Mostly used an air compressor, a careful brushing to spot clean stubborn dust.Both units no longer detect jog wheel rotation. They do detect jog wheel touch. Everything else works fine.I've tried reseating the FFC cable from the jog dial section to the display section.The second I did wearing gloves.Thetroubleshooting section of the service manualpoints to a defective "Encoder Plate" but there is no mention of an encoder plate in the rest of the manual. I was instructed in another group to 'refitthis pieceto make sure the plastic is between the sensor'. Could someone clarify if this is the "Encoder Plate" or tell me what it is?Next time I'm in the units I will be trying what was suggested and making sure the holes in the Jog Dial and the Sensor are aligned.Has anyone had and solved this problem before?Does anybody have any general advice for working on these jog wheels/CDJs 3000's they think could be helpful?Last: I'm new to repairing Pioneer equipment and I would be super grateful if anyone could share other communities with this more specific subject.Thank you all in advance.

author: fenugrec
author_rank: Frequent Contributor
timestamp: October 12, 2025, 12:38:39 pm
content: I worked on an old CDJ-100 a while back, different principle though, not really applicable (those used a plain off-the-shelf rotary encoder with mechanical contacts which eventually go bad).In your case the small PCB you showed would have two optical sensors with a small offset, and what I presume they call the 'encoder plate' would be some sort of disk with holes or notches that need to go through the slot in the optical sensor block of that small PCB - think "interrupted beam sensor". The two sensors being offset inside that block, you get a quadrature output, just like any plain rotary encoder.
CDVG_E440 chip info? - Page 1
Forum section: electronics / repair

author: Erik Lander
author_rank: Newbie
timestamp: January 17, 2024, 01:27:35 am
content: I am debugging an intermittent problem on a 1998 volkswagen instrument cluster. The MCU that runs this thing has a logo of ITT and a part number of CDVG-E440 then other numbers below that. Has anyone here ever heard of this chip or family? A fairly exhaustive crawl of the net has yielded precisely nothing. I did find out that ITT Microelectronis was acquired by Micronas in 1997, but there is no info about any ITT legacy devices on their website. Any clues will be most appreciated.Erik Lander

author: coromonadalix
author_rank: Super Contributor
timestamp: January 17, 2024, 01:55:24 am
content: well it may be custom made, i've seen on some VW threads year 2010 questions about this mcu, and sadly no answers ??you shoud try on some VW forums ??good luck

author: Erik Lander
author_rank: Newbie
timestamp: January 17, 2024, 02:54:40 am
content: Thanks for the pic, that's the chip. I hadn't considered the possibility of a custom chip, I have searched the VW forums and while there are lots of threads about problems with clusters using this chip, there is no useful info. There are whispers about it being a Programmable System on a Chip - PSOC but even VW's volume wouldn't seem to amortize a full custom design, more like a semi custom arrangement of function blocks around a core. Big NRE up front but easily justified for a couple hundred thousand units.And there were comments about professional shops that repair these clusters being able to talk to that chip, which indicates that they had sort of cracked it. I'm not interested in reverse engineering it, just enough to determine if the problem lies elsewhere. The tach and speedo are stepper motors, and the drivers are inside the chip.I was hoping to not have to start from zero on this, I do have a benchtop lab at home, fast scopes, logic analyzers etc, but not really suited to mobile applications. Perhaps time to buy a Picoscope.Erik

author: coromonadalix
author_rank: Super Contributor
timestamp: January 17, 2024, 03:20:16 am
content: sometimes people find or hack stuff as you know, and get a good experience out of this, maybe some found out the protocols, or a way to connect a jtag an spi programmer etc ... or found out some rare datasheet or even some people at VW may have leaked some stuffor even uncap the icanything is possiblewe dont know ...
CEC DX51 digital to analog converter pops when music starts - Page 1
Forum section: electronics / repair

author: penmarker
author_rank: Contributor
timestamp: September 06, 2024, 10:06:57 am
content: Hi everyone hope everyone is doing great.I acquired this DAC and looking for a popping solution.The right channel will pop whenever audio starts playing. It can be replicated by either play/pause or turning volume up from 0.(Picture 1)There are a pair of CHAMP Modules (red, horizontal with many LEDs) which I assumed was the cause. After swapping the cards the popping did not swap so it could be up stream.The three boards (vertical) are Decoder board, Digital Filter board, and DAC board.(Picture 2)The dac uses 4 PCM1704 chips.No service manuals are available and information is sparse.The DAC board also has 2 kinds of tantalum caps. One is marked 47 10V. Another is marked 47 10g.What does the g stand for?Aside from the popping and slightly higher noise floor compared to modern DACs, it sounds good.Need some help to nudge where I should start prodding.Pop appears on both hot and cold out. RCA and XLR both pops
CEC P85 - Unknown Component - Page 1
Forum section: electronics / repair

author: 2X
author_rank: Frequent Contributor
timestamp: September 25, 2023, 05:36:55 pm
content: Hello,I have the below component on a power supply but I can't understand what it is. I measured it with 121GW Multimeter with diode mode (15V scale) and the results didn't give me a clear picture of what exactly is this component.http://www.smdmark.com/en-US/search/code?id=P85]http://www.smdmark.com/en-US/search/code?id=P85http://markingcodes.com/search/c/P85https://en.wikipedia.org/wiki/Small-outline_transistor]https://en.wikipedia.org/wiki/Small-outline_transistor

author: fzabkar
author_rank: Super Contributor
timestamp: September 25, 2023, 05:41:40 pm
content: BC860 or BC869 ?http://markingcodes.com/search/c/cechttps://www.ebay.co.uk/itm/166134805524https://i.ebayimg.com/images/g/RXoAAOSwKNliWMdM/s-l1600.jpg(photo)BTW, it's P85, not P58.

author: 2X
author_rank: Frequent Contributor
timestamp: September 25, 2023, 06:01:22 pm
content: Thanks for the reply. The P85 means something? I will go with the BC869 because it is the same in electrical characteristics with the BC860, but the BC869 is available for buying in many places.One more thing... there where the multimeter shows approximately 10V... why shows 10V and not OL?P.S. My mistake P58.

author: fzabkar
author_rank: Super Contributor
timestamp: September 25, 2023, 06:11:25 pm
content: I'm guessing that "85" is a YW (Year/Week) date code.I'm not familiar with your meter.

author: 2X
author_rank: Frequent Contributor
timestamp: September 25, 2023, 06:13:37 pm
content: Many thanks for your help.

author: Swake
author_rank: Frequent Contributor
timestamp: September 25, 2023, 08:41:00 pm
content: Was it still soldered on the PCB when you measured it? If that is the case then that 10V reading is interference from other components on the board.If you want to make 100% certain it reads ok, then you measure it removed from the board.You mention that you want to buy some. Is this because you think it is broken and want to replace it? I don't think it is broken because on your schematic between left pin and middle pin you measure a junction (0.7V), and from the left to the right pin too. That sounds like a transistor to me.

author: Swake
author_rank: Frequent Contributor
timestamp: September 25, 2023, 08:42:25 pm
content: Datasheet for BC869

author: 2X
author_rank: Frequent Contributor
timestamp: September 25, 2023, 10:56:55 pm
content: Quote from: Swake on September 25, 2023, 08:41:00 pmThe measurements that I 've done was with the component removed from the PCB. I too beleive that is a tranzistor.
CEM Clamp Meter High power consumption - Page 1
Forum section: electronics / repair

author: amindavid11
author_rank: Contributor
timestamp: July 30, 2022, 06:17:37 pm
content: Hello!I recently bought what appeared to be an unbeatable deal,https://www.ebay.com/itm/185384482305.It worked fine but the low battery light came on after a few minutes of use, I checked the power consumption andstrangely that problem only happens sometimes when changing modes on the meter, and sometimes it does not happen. The only way for the current consumption to go back to normal is to turn it off and back on again and hope that the high current consumption does not come back.Any help or clues would be appreciated.
CEM DT-9912 - Page 1
Forum section: electronics / repair

author: lionelkjh
author_rank: Frequent Contributor
timestamp: February 23, 2021, 04:14:58 pm
content: Good morning all! I am looking to find 2 voltage regulators (marked: U4 and U5), for an ST-9912 multimeter; the original regulators are not the correct ones. I have attached the pictures of the multimeter. Thank you for your help.

author: TiN
author_rank: Super Contributor
timestamp: February 24, 2021, 03:50:23 am
content: This ain't repair section. You'd have better luck if move thread to Repair, thanks.
CEM DT-9989 multimeter repair - Page 1
Forum section: electronics / repair

author: Mr Evil
author_rank: Regular Contributor
timestamp: October 06, 2023, 03:49:35 pm
content: Recently I picked up my CEM DT-9989 multimeter, and noticed that the back was loose. I thought that maybe the screws had somehow worked themselves out, but 5 of them just span around when trying to turn them in either direction. On unscrewing the one non-loose screw and removing the back, it bacame clear what had happened: the screws screw into plastic pillars, 5 of which had snapped off.The meter was an ex-display model, so I don't know what sort of treatment it had before I got it, but it has mostly just sat on my desk in the 8 years I've owned it, never being dropped or roughly handled, so I don't know what caused the plastic to fail. All 5 pillars snapped off at the same place, just above the PCB. It's disappointing that they didn't use brass inserts in the first place, given that this was an expensive piece of kit, even when not-new.Since there was still a few mm of each pillar remaining, I tapped the holes in them and fitted some brass standoffs in their place. M3x12mm (+6mm male threads) fitted exactly. I used epoxy on the male threads to make sure they can't unscrew when I take the back cover off again.And now it's back together securely. Maybe there's something wrong with the plastic itself, and something else will fail in the future, but for now it's useable again.
[SOLVED] - CEPEM IX3 induction hob power board schematic. - Page 1
Forum section: electronics / repair

author: shakalnokturn
author_rank: Super Contributor
timestamp: October 15, 2019, 01:05:42 pm
content: I have an induction cooker that fails to detect the pan.The IX3 induction is a French/German design from the mid '90s that was used on many induction cookers until around 2005.Sauter SED3N1 and Thermor 1448X1 are both based on this design.To avoid the hassle of a little reverse engineering I'd need the component level schematics for the power board 7942-2391.I know it must exist as there is one ancient post on this forum with a partial schematic of the housekeeping supply part of the board.Thanks...

author: shakalnokturn
author_rank: Super Contributor
timestamp: November 07, 2019, 01:51:18 pm
content: Aide toi, le ciel t'aidera...The board i was trying to fix I had been given with unknown history.One of the output switching relays was charred (a common problem) and there were many weak solders.Before testing the PCB I set out to replace the relay and refresh the worst solder joints.On first test when it failed to detect the pan I guessed that the output current measurement was the cause.laying a spare inductor linked to an oscilloscope on the defective side of the hob revealed that there was no output to the inductor at all, so obviously if there is no output there is no current to be measured...I checked all the housekeeping supply voltages to be OK. (-6V, +9V, +12V) Then spent a while drawing a partial schematic from a parts PCB I had hanging around.Once my schematic was complete enough I started probing with my isolated scope, first on the working PCB to know what to expect.On the defective PCB I was getting output from the UC3524 up to the collectors of Q3 and Q4 but nothing on the driving transformer primaries that are only separated by a 47ohm resistor.A shorted transformer or shorted Q5/Q6 MOSFETS could have been the cause.It wasn't, after scratching my head and probes at this for a few hours, I spotted it: A tiny solder link (that maybe I caused myself) between R11 and R12 on the transformer side shorting out the two opposite windings...So this topic was an adventure and waste of time from and for me, myself and I but make the most of it now I've gone to the trouble...
Ceramic Cooktop Switch - EK755 - Failed touchless switch - Page 1
Forum section: electronics / repair

author: fabfab
author_rank: Newbie
timestamp: March 08, 2022, 05:11:29 pm
content: Hi.I need a little help. My Ceramic Cooktop Siemens EK 755 has a 'touchless' switch to switch on the outer / bigger heating element for bigger pots and pans.You touch the glass and below the glass there is the switch.The problem - it does not work anymore. I replaced it with the second one > Everything works fine. So its definitly the switch 75.12000.153 62791002 62662003.I have litte understanding which component could have failed, but are able to replace them.Do you have a clue, which component has failed?I attached a pictures of the switch and the heatmark. I forgot to make a picture of the second backside where the relay (between 4 and 4a) is.Can you give me a hint, where to start looking / what to replace?Thank you very much for your expert advice.

author: fzabkar
author_rank: Super Contributor
timestamp: March 08, 2022, 08:14:18 pm
content: Is there a 1uF 250VAC film capacitor underneath the larger PCB? I'm expecting to see a transformerless supply for the IC on the switch/lamp PCB.The pinout of the ribbon cable seems to be as follows:relay drive output from SOIC-8 ICDC positivelamp supply positiveDC negativeThe burnt (?) component appears to be a zener diode which sets the supply voltage for the IC. It would be part of the transformerless supply. It often goes short circuit in this topology.

author: fabfab
author_rank: Newbie
timestamp: March 14, 2022, 10:35:56 am
content: Dear fzabkar,thank you for your answer. I currently don't have the possibility to make more pictures.Do you think it is worth/possible to replace the ZenerDiode? Or did the short circuit do more damage?What kind of Zener Diode would I need?Thank you

author: fzabkar
author_rank: Super Contributor
timestamp: March 14, 2022, 04:28:16 pm
content: Measure the voltage between DC positive and DC negative at the ribbon connector on the working unit. That will be the voltage of the zener diode.

author: fzabkar
author_rank: Super Contributor
timestamp: March 16, 2022, 08:14:09 pm
content: This is the kind of transformerless circuit you should expect to see on the other side of your PCB:https://www.eevblog.com/forum/repair/coffee-grinder-failing-motor-ok-but-electronics/?action=dlattach;attach=1440436;image
C/ESR Measurement - Page 1
Forum section: electronics / repair

author: jdragoset
author_rank: Frequent Contributor
timestamp: October 06, 2019, 12:51:08 am
content: Any thoughts on a decent(affordable) C meter that also displays ESR?I'm currently using a Tenma 72-960 LCR meter that displays "D" with capacitance measurement, where I'm advised that ESR = 1/D.

author: DimitriP
author_rank: Super Contributor
timestamp: October 06, 2019, 01:30:25 am
content: Practically free (or about $10-$20 US ) you can't beat the component tester found on ebayNext step up will be the PEAKLCRAtlas ESR70 tester unless you are building satellites or medical equipment in which case the sky is the limit

author: DimitriP
author_rank: Super Contributor
timestamp: October 06, 2019, 01:45:43 am
content: ...and in case anyone is wondering the "sky" starts at about 13Khttps://www.keysight.com/en/pd-1452259-pn-E4981A/capacitance-meter?nid=-34124.798589.00&cc=US&lc=eng

author: mr.fabe
author_rank: Regular Contributor
timestamp: October 06, 2019, 02:15:39 am
content: The Peak LCR tester will not measure produce an ESR measurement and in-circuit measurements are not recommended. You will need to discharge capacitors prior to testing like most LCR meters. It will test capacitance, inductance, and resistance at a few different frequencies. If you are looking for a decent unit that can measure capacitance and ESR, my vote would go to the Peak Atlas ESR70. The unit discharges caps up to 50V, does in-circuit measurements, and you can use different test probes (alligator, hooks, probes, etc.). I also have the inexpensive MESR100v2 that does a good job with reading ESR but that it. The leads are short, you need to discharge caps before testing, and no capacitance measurements.
CF-IDE40 V.EO knockoff? - Page 1
Forum section: electronics / repair

author: mictas
author_rank: Regular Contributor
timestamp: June 27, 2024, 06:17:38 am
content: Well after picking up an eBay order, I have been left feeling a bit off.My grand master plan is to use one of the CompactFlash card or buy a larger one for use in one or two older desktop computers and/or a laptop.The interface adapter I was sent isn't 100% same as on the eBay listing, apart from the bent pins on the eBay listing I can see a resistor under the CompactFlash slot, but with the unit shipped to me, it has a capacitor.Was this anything I might need to switch out or should it be safe to use as is?
CH341A Black usb fry - Page 1
Forum section: electronics / repair

author: noobitynoob
author_rank: Newbie
timestamp: March 21, 2020, 05:28:32 am
content: Hello experts,I recently received my new CH341A miniprogrammer. I followed all steps to get ready, found my target chip, MXIC MX 25L4006E chip that I think is the target I wanted to test reading from.The target chip board was powered down for many days.I connected my 25 series 8 pin through the adapter and locked it in, pretty straight forward. Pin 1s were all aligned with careful attention, as well on the chip (still on the board).I was attempting to get the second led to signal that it had found the chip, I reseated a few times. I left the usb device plugged in, and the clamp on the board while reading some notes, and about 30 seconds passed and I got a "Pop" and some sweat smelling ozone, definitely from the CH341 itself, not the target board, or the host USB controller/port luckily.The USB port on the host controller is still operable for other devices, but now my CH341A is not detected by the OS (linux) - where it was previous. However, the LEDs both light up now, clamp on target chip or not.I've read about a fix here -https://www.eevblog.com/forum/repair/ch341a-serial-memory-programmer-power-supply-fix/msg1323872/#msg1323872but this was more about preventing damage to the target chip, not the USB device itself. It's the closest issue I can find that maybe someone else has had but seems distant from my issue.Being a noob at this, I'm wondering if anyone else has encountered this?FYI - I was plugged into a USB 3.0 port if that matters, I thought that the 5v would be OK, but I'm sure there's some reason why that might matter for these small devices.Any help or advice on similar issues or where to go next with this? Of course, I can just buy a new one (A green one is already on the way for me to also destroy) but figured I would ask here. Or at least start a thread if others also run into this. It's so cheap it isn't worth fixing so maybe folks don't ask.Thanks

author: pupa
author_rank: Contributor
timestamp: May 27, 2020, 08:25:31 pm
content: Can you see what fried on the CH341A board? If you smelled something then you should be able to see something I hope. How was it connected when it happened? USB3 5V is the same as any other USB port. You cannot easilly fry the CH341A with the USB5V. Please add photo and/or more info if you still need help.Read this link about the CH341A Power supply issues blowing chips.https://www.eevblog.com/forum/repair/ch341a-serial-memory-programmer-power-supply-fix/
CH341A Programs Correctly but BIOS Still Won't Work  - Page 1
Forum section: electronics / repair

author: shuten
author_rank: Newbie
timestamp: December 06, 2022, 06:56:14 am
content: hi all, so i have an acer XC-605 desktop which i believe had a bad bios flash.i setup an ssd for it and it didnt get recognized in the bios so i attempted a bios update with the provided gui from acers website (going from P11.A2 to P11.B4). i rebooted and it seemed the bios update was successful but when i turned off the pc, it would no longer turn on properly and gave me one long beep (fan goes on, maintains power but no display etc, seems to fail post).i tried a bunch of stuff like reseating ram etc and tried to reflash from usb but since nothing worked i eventually just bought a ch341a and tried to manually flash it.so when i connect the clips and run the ch341a software, everything looks fine, i can read the chip (MX25L6473E) and write to it, and the software verifies and shows me successful prompts, however the PC still does not start up. i no longer get the beep at startup so i know something definitely changed, but i still get nothing on display.i tried multiple programmer software and various bios versions but get the same results.ive used, asProgrammer, NeoProgrammer, CH341A programmer by Shichang Zhou, but no difference.even tried changing the chip size in the software to 4MB since the bios file is 4MB.mobo model is MS-7869 v1.0 for referenceim sure it must just be something im missing but i have no idea, anyone have any ideas or suggestions?thank you!