hybridfree/eevblog-posts huggingface dataset:
Crt tube pinout - Page 1
Forum section: electronics / repair

author: awesomechapro
author_rank: Contributor
timestamp: December 11, 2022, 02:14:24 pm
content: Hello all, I am trying to repair a dead crt monitor and have gotten stumped on the pinout of the crt tube itself. It is a Samsung A34KQV42X. Does anyone know the pinout of this tube, or can help me figure it out? I have identified the heater pins, but that’s it.

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 11, 2022, 03:18:10 pm
content: Can you find the service manual for it? I found one that is supposed to have this CRT inside, maybe it helps.
CRT Tube Rerference - Page 1
Forum section: electronics / repair

author: glaird
author_rank: Newbie
timestamp: September 30, 2025, 12:15:13 am
content: Is there a database or some sort of reference for CRT tubes?I have a 17" B&W crt tube, part number 17ST5490C that I would like to see a data sheet for. I would like to replace the tube and I can buy a 17ST5490C3--I would like to know what the '3' suffix means.This crt tube is used in a motorola video monitor in a bowling alley automatic scoring system. I used to have these monitors rebuilt by Scotty Avitt at Hawkeye Picture Tube, but he has since closed. I have also bought some of these crts from Video Display Corporation, but I think they no longer sell them.Thanks,Greg Laird

author: Andy Watson
author_rank: Super Contributor
timestamp: September 30, 2025, 01:01:30 am
content: Try this site:https://frank.pocnet.net/It is the most comprehensive site that I know for valve/tube data. If it's not there, it probably hasn't been put on the web.

author: glaird
author_rank: Newbie
timestamp: September 30, 2025, 08:26:09 pm
content: I did look at the site and I didn't find the crt listed. This crt, the 17ST5490C, was a tube I used to replace a Sylvania 16VAJP4 crt. I think that Hawkeye Picture Tube did the initial cross for me. I can't find the 16VAJP4 on the site either.Thanks for your suggestions.

author: TimFox
author_rank: Super Contributor
timestamp: September 30, 2025, 08:29:49 pm
content: Does this work for you?https://crtdatabase.com/Frank's is a wonderful site for vacuum tubes, but I don't believe it ever showed CRTs.

author: glaird
author_rank: Newbie
timestamp: October 01, 2025, 02:05:12 pm
content: I have already looked at that site. I didn't find either CRT number.Thanks though.
CRT TV has brightness problem, need help to identify what is causing it - Page 1
Forum section: electronics / repair

author: nahuel0909
author_rank: Newbie
timestamp: July 04, 2023, 05:29:27 pm
content: Hi!I have a Philco PM2014 (I attached the manual of the PM2024 model, which is the closes thing to my model I could find and they seem to be pretty similar).The issue happens when I'm using the TV on AV mode, it does not seem to happen on cable mode.Basically the screen goes brighter and dimmer randomly, usually after a few moments of usage the screen might go noticeably brighter and it will stay that way for some time. Then the brightness might go down again and stay that way for a few moments, then it might go dimmer than normal, so on and so on. It's very noticeable and annoying.I already took it to someone who repairs a lot of these old TVs and he didn't find anything wrong and I belive this is because he tested the TV on cable mode, so my conclusion is that this only happens on AV mode. I don't know how weird this is but it might help identify the issue?The things I did is cleaning the TV inside and messing around with the flyback transformer but nothing changed.Also I'm pretty sure it's the TV and not my AV devices because it happens both with my PC that I connect using an HDMI to RCA adapter and with my PS2 as well.If you need any information or pictures I can provide to help identify the issue let me know.Thanks!

author: james_s
author_rank: Super Contributor
timestamp: July 04, 2023, 06:51:45 pm
content: It sounds a lot like the effects of Macrovision analog copy protection, is the source material copy protected movies? Do you have any other displays that accept analog composite video to check with?

author: nahuel0909
author_rank: Newbie
timestamp: July 06, 2023, 11:54:07 pm
content: I'm pretty sure its not any copy protection involved here

author: james_s
author_rank: Super Contributor
timestamp: July 07, 2023, 06:12:30 pm
content: I just can't see how the fault would happen only using the baseband video input and not going through the tuner, the tuner will output a baseband video signal. I would look at anything in the input chain from the A/V jacks to whatever switching selects which input is used.
CRT TV Repair: image jitters and shakes horizontally left and right - Page 1
Forum section: electronics / repair

author: luke.simon
author_rank: Newbie
timestamp: August 08, 2020, 03:32:37 am
content: Seethis video of the symptom. The video shows a 240p resolution Playstation 1 game, connected to the TV over high quality component video cables (ypbpr), and the game is paused. The image is supposed to be completely stationary with no movement, no animation, but the blue clothing of the character is clearly jittering or shaking or rippling left and right. I have tested this exact same set up on other CRT TVs that I own, I have confirmed there is no movement in the image. On the other CRTs that I own, the character’s blue clothing does not move or animate.I thought it might be a bad liquid electrolytic capacitor, so I replaced every single electrolytic capacitor, and tested to see if the issue was fixed. The issue persists even after replacing all of the electrolytic capacitors.There are no other issues with the TV. The jitter seems to be the most pronounced where the scanline is brighter. In the video linked above, the character’s blue clothing is very bright blue and the jitter is very clear. For bright red the jitter is slightly less obvious, and for bright green it is the least obvious. However, the jitter does exist for red, green and blue, though it is the most pronounced for blue. White uses all 3 colors so bright white is also as noticeably jittery as bright blue.I thought it might be an issue with the horizontal deflection circuit, so I used the 240p test suite to display horizontal white lines for each illuminated scanline in a 240p resolution, and then I tuned the horizontal position in the TV service menu to see if the edges of the illuminated scanlines jittered at the left and right ends of each illuminated scanline and there is no visible jitter! This suggests the issue is not with the horizontal deflection circuit because otherwise the ends of the illuminated scanlines would stop and start early and late with the jitter.Is the issue with the RGB color signal path? I am new to CRT repair, so any tips on how to approach this would help.

author: Skatino
author_rank: Newbie
timestamp: May 03, 2025, 05:25:55 am
content: Quote from: luke.simon on August 08, 2020, 03:32:37 amHello, i have the same issue with a Panasonic Quintrix CRT.Did you manage to fix your problem ?
CRT Video to Digital monitor compatability issue - Page 1
Forum section: electronics / repair

author: DonT
author_rank: Newbie
timestamp: January 22, 2025, 08:47:41 pm
content: I have a Video output from a PCB with no capability for adjusting it's Vertical signal. I tried several digital displays but all have the top and bottom line of data not displaying. I tried selecting all aspect ratios with no success. Horizontal is perfect.Is there a scalier which will help?

author: coromonadalix
author_rank: Super Contributor
timestamp: January 23, 2025, 01:57:52 pm
content: what is the item who provide the video photos etc ... you don't provide much to helpcould be impedance signal or many things

author: DonT
author_rank: Newbie
timestamp: January 27, 2025, 07:51:19 pm
content: The signal is created from a Printed Circuit board which is on an electron Microscope manufacture by JEOL LTD. They do not provide any information on this output. This output goes to a box which has no adjustment other than brightness. This box or Circuit is made by Teli in Japan 9M10N BE1198A9

author: benj38
author_rank: Frequent Contributor
timestamp: January 27, 2025, 09:56:00 pm
content: As @coromonadalix says, we need more information. Given that we are talking about quite uncommon equipment, with no documentation according to what you say, I would try to look at the ICs on the PCB and read their datasheets. If you are lucky, this may pin down some of the information you need. Some photos of the PCB may help us suggest which ICs are the important ones to investigate.

author: Whitefoot
author_rank: Contributor
timestamp: January 28, 2025, 08:57:09 pm
content: It might conceivably be a PAL/50Hz video output feeding to NTSC/60Hz monitors, or maybe some other video mismatch.
crystal frequency  - Page 1
Forum section: electronics / repair

author: salviador
author_rank: Regular Contributor
timestamp: May 14, 2024, 11:59:52 am
content: Does this crystal have a frequency of 33.6MHz?This quartz is connected to a CC1120

author: ftg
author_rank: Frequent Contributor
timestamp: May 14, 2024, 02:14:33 pm
content: If it is connected to the pin 32 of the CC1120, then it very much could be a 33.6MHz crystal oscillator.It might be a TCXO if the device is doing some long range narrowband stuff on 868MHz or 900MHz bands.TI CC1120 datasheet does give 33.6MHz as the maximum typical value for the reference oscillator.The oscillation frequency should be relatively easy to confirm by probing the output pin with an oscilloscope.1. Section 4.9, on page 14https://www.ti.com/lit/ds/symlink/cc1120.pdf

author: salviador
author_rank: Regular Contributor
timestamp: May 14, 2024, 04:01:25 pm
content: Exactly it is on pin 32 as external TXCO.Unfortunately I don't have the original to take measurements, I only have a photo of an original one.It works in a frequency of 869.203500 MHz2FSk modulation.I put a TXCO of 33.6M. I tried to clone with flipper zero but strangely the pinball machine doesn't replicate the right code!I also wrote on the flipper forum with all the settings but no one responds. I do not understand the issuehttps://forum.flipper.net/t/2fsk-baud-rate-2400-problem/25427
Crystal Impedance Meter Saunders & Associates 150B - Firmware wanted - Page 1
Forum section: electronics / repair

author: rwweichler
author_rank: Newbie
timestamp: June 28, 2022, 09:52:34 pm
content: Hello everyone,the Crystal Impedance Meter Saunders & Associates 150B has been discussed here already in 2018. I hope, some of the contributors from that time still have their device and are willing and able to help me.I had bad luck with mine. I wanted to use my instrument to get the parameters of the crystal in an Rb Standard in order to compensate the ageing and to set up the oscillator again to its specifications.During the measurenents the blocking capacitor OC56 across +15 V and -15 V at the output stage of the measurement oscillator got a short and has drawn a high output current from the power supply. This led to a significant increase of the +5 V rail (the crowbar circuit triggered way to late), and several logic-ICs were killed. Among them are the EPROMs, too, of which I unfortunately didn't take any backups.Now I would like to ask whether someone could provide me the EPROM files from his/her instrument. I'd really appreciate a positive feedback. Everything else is still available at moderate costs from eBay and Digi-Key, but without the firmware I won't be able to get the unit running again.My instrument has been made probably in 1980, and the FW version 1700 is quite old. I wouldn't mind about other FW versions. From what I've learnt, the FW versions relased over the time are compatime with the HW versions. Even the FW used in the successor model 150C should be working.If you are interested, attached is are the screenshots of the digital and analog PCBAs with the location of the broken capacitor. I found another leaky one, it might be an idea to check them all.Thanks so far and kind regards,Rolf
CS5340-CZZ ADC white noise troubleshooting - Page 1
Forum section: electronics / repair

author: FranciscoPerez
author_rank: Newbie
timestamp: July 20, 2023, 11:20:48 am
content: Hi,This is my first post here, long time analog electronics repairer and builder, a customer brought an acoustic guitar amplifier for repairs. The amplifier makes use of some digital circuitry to provide reverb effects, which is producing a high white noise.Managed to trace down the problem down to U201 /RST Input (CS5340-CZZ) Analog to digital converter. Shorting C222 gets rid of the noise but turns off the amp effects, since /RST input is at low level, of course.I removed C222 and R201, and the noise was still present. However, with those componentes removed, when I tap U201 pin 9 with anything metal (a multimeter probe, screwdriver etc) Noise goes away and I can get the amp to work as expected.What do you guys think could be causing this? I'm quite new to digital circuits, and do not have access to an oscilloscope. Replaced R201 with a jumper and C222 with a new cap, but the problem remains.Thank you for your help.Best regards,Fran

author: coromonadalix
author_rank: Super Contributor
timestamp: July 20, 2023, 04:57:38 pm
content: unless STC 809 is defective change c222 and try again ?? rst line should not affect things like thatits a power management deviceu201 could be defective ??do you have a scope to check the 5v line, it could be noisy ...you have many filetirng capacitors around u201, changing them could be helpful

author: Kleinstein
author_rank: Super Contributor
timestamp: July 20, 2023, 05:06:22 pm
content: Having the ADC in reset is not really helping with noise, more like turn off the path.Connecting the pin to some metal parts may either reset the chips and this way change some settings (e.g. amplitude to small). Another possibilty ,may be connecting the metal part via the reset pin and C222 to ground to keep EMI away from the circuit. It may thus be worth checking the shielding and ground connection.

author: FranciscoPerez
author_rank: Newbie
timestamp: July 21, 2023, 10:10:56 am
content: Thank you guys.Already Changed C222 without success. STC809 should not be defective, since removing R201 and therefore disconnecting the STC809 from the /RST input does not make any difference and the noise is still there. I don't have access to a scope, but I doubt the 5v line to be noisy given the noise is not constantly there, and disapears after poking pin9 with some metal part.It might well be a defective u201, but hope not, since I'd hate to remove and solder a new one, being such tiny chips.I'm about to try changing some filter capacitors around U201, as well as playing with shielding around it and see if that helps.Thank you!Fran
CSA8000 modules - Page 1
Forum section: electronics / repair

author: cncjerry
author_rank: Unknown
timestamp: December 23, 2019, 01:55:45 am
content: I have a CSA8000 I've repaired. Now I am looking for electrical modules. Can they generally be repaired or hacked to work?I assume there is some amplifier right on the frontend that get's blown. Seeing that they are good to like 50gig, they would be almost impossible to repair, I assume. But if it is an amplifier, what about replacing it with something less expensive? I know you won't get 50gig or anything calibrated out of just any old amp, mmic, etc but if I was interested to up to 4gig or maybe just to screw around, is there something I can do with these blown modules?I rebuilt this CSA8000 and it is still sitting all over my lab in pieces because I've been waiting to find a module that will at least let me test it. Of the 6 or 8 ports, at least 4 are reporting ok. So I figure if I get a module or two, it will at least get some lines on the screen. These things were meant for high-speed telecom line testing, something that though I worked in telecom for years, I will never plug an OC48 into it. The TDR modules are $3k+. I got the CSA800 for $150, I think I have another $50 in it, and I would love to see it at least put up a trace.ThanksJerry
CSA8000 - Page 1
Forum section: electronics / repair

author: cncjerry
author_rank: Unknown
timestamp: July 12, 2019, 05:21:04 pm
content: so I can pickup a CSA8000, looks in good shape but needs disk and OS repair. No modules and that's the issue. Are there any low-cost modules for this unit? An answer to this question might be, "...oh yeh, all you need to do is purchase one of these broken ones on ebay, swap out the whatever, and then you have a working module."Every module that works looks like it costs about $2k or more. I assume none of the other modules work in it that would be in the 11801, for instance?Thanksjerry
Ctek battery charger MXTS 40 - Page 1
Forum section: electronics / repair

author: najrao
author_rank: Regular Contributor
timestamp: February 18, 2024, 11:24:53 am
content: Got this only to see what is inside, and repair if possible as necessary. The elaborate case with buttons and display is taken off for later.First, I don't see any hv bulk cap after the rectifier. The 'top' picture does show 4 unpopulated circles for caps, but these are decapitated by someone who was in earlier. They are bulk (all in parallel), but on the lv side. I must determine if 1000uF 35V 105C ×4 would refill the spaces correctly.Even with a small internal fan, 40A to rectify and 660W to handle on the primaries of the two transformers together appears to be a tall order for the heat sinks. Let us see.I shall revert to this after I get time to do some study. If you have seen this charger before, do let me know what to expect. Thank you.Edit: there is no fan provision. Mistook the the header socket on PCB, goes to external thermistor temperature sensor.Edit: I fitted 4×1000uF 50V in the vacant positions. Should probably be 2200uF 35V, per my analysis, but had no stock.Edit: Fuse was blown and shorted by previous genius. Replaced.Edit: Invisible track fault on PCB had blown a TL2575HV (intermittance causing loss of connection to ground pin). Replaced by stock 2576 not HV.If any of you have this charger, request check rating of capacitor to determine if more than 4000uF is needed. This is the main and only energy storage and filter. Thanks.

author: najrao
author_rank: Regular Contributor
timestamp: February 26, 2024, 01:56:35 pm
content: Not interesting to anybody, apparently. But I shall put down my findings so far for posterity, and perhaps once again seek your indulgence to find answers.The two phase "PFC" is actually a rather neatisolatingflyback, using a UCC38060 for PWM. With two separate 'coupled' inductors, aka transformers, it puts out up to 660W of dc at 52.5V (sic). No synchronous rectification, just STTH's to do the job. Regulation is in the secondary part, usingthreeparalleled TL431's, two of which are identical and are indeed set up forexactly52.5V. Perhaps some funny redundancy to prevent overvoltage. The third is more complex, but does not influence the setpoint of control. All three feed into justoneoptocoupler(PC817).So I changed the dc bus caps to 63V 1800uF×3. I also added a zener follower to limit the voltage to the auxiliary switcher 2576, to 37V.There are no further stepdown converters after the 52.5V bus!There are two more mosfets on the heatsink, yet to understand what they do. No more inductors or rectifier diodes.The charging control by software seems to work as should. So does the pretty display.I just can't fathom how to charge a 12 or 24V battery from a stiff 52V bus without further conversion. I tested with a 12V 10Ah battery for a few minutes, and it works! Can anyone?Edit: Horrible oversight on my part - failed tonoticehuge inductor with twisted wire 10AWG winding. Straightforward stepdowner after all.
CTEK MXS 7.0 Battery Charger - What Is The Burnt Out Resistor? - Page 1
Forum section: electronics / repair

author: mackembazza
author_rank: Newbie
timestamp: April 14, 2022, 09:35:44 pm
content: I have a CTEK MXS 7.0 which died. Resistor R1 has burnt out so I can't see all of the coloured rings and was wondering if someone on here new the value. The first ring is yellow, second is totally burnt, 3rd might possibly be black (but can't be sure) then 4th and 5th are gold. If 3rd ring is definitely black then I know it's likely to be 40, 43 or 47 Ohms. Hoping someone can confirm please?

author: yanalesch
author_rank: Contributor
timestamp: April 15, 2022, 08:04:10 am
content: Does your circuit look like in the picture I found online? And is it the same resistor that burnt?If yes, reffering to this german forum:https://www.7-forum.com/forum/archive/index.html?t-167268.htmlIt is an 33 Ohms resistor with ~ 1 Watt . The early revisions had an 24 Ohms resistor, and later revisions got an 33 Ohms resistor. But it is unlikely that the resistor is the culprit, you may consider to track which components are in series to it. In the forum I refered to the mosfet also was defective.

author: mackembazza
author_rank: Newbie
timestamp: April 16, 2022, 03:07:31 pm
content: Quote from: yanalesch on April 15, 2022, 08:04:10 amUnfortunately that one is different. Mine is a bigger resistor, probably 2 or 3watts, and is hidden under a heatsink. Thanks for your suggestion.

author: yanalesch
author_rank: Contributor
timestamp: April 16, 2022, 05:27:03 pm
content: Maybe the images in this threads can help you:http://www.ittsb.eu/forum/index.php?topic=937.0https://www.mikrocontroller.net/topic/351174
Cullpower Power Supply (from Mikrotik Router) - what is DP81 chip? - Page 1
Forum section: electronics / repair

author: cte
author_rank: Regular Contributor
timestamp: January 12, 2024, 10:53:59 pm
content: The network router in the basement was not working and I found its wall wart was hotter than it should be. When you work with electronics you get a feeling for if something something is getting too hot, even when it is encapsulated in a plastic case.As expected there was no power at the output (it is rated 24 V DC / 1.2 A). After opening the device forcefully, I found the schottky diode on the secondary side shorted. Everything else seems okay. So I wanted to know what was heating up.With primary power applied, the SMPS runs in intermittent mode as it should be due to the shorted secondary side. But the MOSFET on the heatsink gets very hot. I measured over 100°C after a few minutes. Probably not the best design I guess.I already replaced the wall wart by something I had floating around, so this is not a repair issue. More kind of a informational post-mortem analysis.And... maybe someone has a clue aboutchip identification: I was curious about the 6-pin control IC labeledDP81 OH18.It's a TSOP6 package with GND on pin 1, feedback on pin 2, output on pin 4 and Vcc on pin 5.I guess it is a clone ofNCP1250 by ON Semibut is there no kind of search engine for those SMD chip markings? Octopart and Duckduckgo had no clue. Google finally pointed into the right direction...

author: cte
author_rank: Regular Contributor
timestamp: January 12, 2024, 10:58:15 pm
content: (forgot to include the identification plate)

author: fzabkar
author_rank: Super Contributor
timestamp: January 12, 2024, 11:41:18 pm
content: DP2281, Depuw.com (Shenzhen Developer Microelectronics Co., Ltd), High Performance Current Mode PWM Controller, marking DP81, SOT23-6:https://compatel.hu/images/Controller/DP2281.pdfhttps://vi.aliexpress.com/w/wholesale-dp81.html
Current clamp hall sensor IC - Page 1
Forum section: electronics / repair

author: Simon123
author_rank: Regular Contributor
timestamp: May 01, 2024, 06:11:12 pm
content: Hello!I have this current clamp with broken hall sensor ic (Leads cracked off from the, cant solder to it)Could anyone help me with identifying this SMD hall sensor? Current clamp is TECPEL DMC039 aka. extech 380941It looks like it says .Q.Thank you in advance, Simon

author: floobydust
author_rank: Super Contributor
timestamp: May 01, 2024, 07:34:05 pm
content: Similar Hall sensor was ID'd in this thread, there's a link to some parts to confirm marking code.https://www.eevblog.com/forum/repair/fluke-337-clamp-meter-hall-sensors/msg5350238/#msg5350238

author: Simon123
author_rank: Regular Contributor
timestamp: May 01, 2024, 07:38:01 pm
content: Saw that. Mine appears to have all 4 pins of same width.

author: Simon123
author_rank: Regular Contributor
timestamp: May 01, 2024, 07:47:46 pm
content: Found this tho, which might be it.https://www.akm.com/content/dam/documents/products/magnetic-sensor/hall-element/in-sb-ultra-high-sensitivity/hw105c/hw105c-en-datasheet.pdfCan't find where to buy it tho.
Current limit on Agilent 6673A PSU activates with a few second delay - Page 1
Forum section: electronics / repair

author: jgorsk
author_rank: Regular Contributor
timestamp: September 06, 2020, 03:44:35 pm
content: The current limit on my HP 6673A PSU activates with a few second delay.The PSU allows drawing higher current than the programmed current limitfor about 5s and then switches to constant current mode with the correctcurrent limit value.Is this normal on this type of PSU?

author: madao
author_rank: Frequent Contributor
timestamp: September 06, 2020, 05:09:37 pm
content: my 6653A (35V 15A), is very fast in regulation and change from CV (constant voltage) to CC (constant current) (less than one 1ms )I think: it is not OK.greetingsmatt

author: jgorsk
author_rank: Regular Contributor
timestamp: September 07, 2020, 07:08:27 pm
content: Thank you for your reply but the 6673A is probably different than the 6653A in the way CC modecontrol circuit works. The time constant of the CC mode control circuit is much longer in 6673A.It looks like switching to CC mode is supposed to take that long and the PSU allows for for the outputcurrent to exceed the programmed current limit for some time. The smaller the output current'overshot' the longer the time for CC mode to kick in.Can someone who has the 6673A power supply confirm this please?

author: 3141592
author_rank: Regular Contributor
timestamp: July 18, 2021, 11:07:30 am
content: I know this is a bit late, but yeah it works the same in our unit too. I was also worried about this. Another thing to maybe look out for is oxidation of the spade connectors, near the current shunt, which resulted in unreliable current measurements in our case.
Current sensing/Power take off socket. - Page 1
Forum section: electronics / repair

author: Mark241
author_rank: Newbie
timestamp: October 07, 2023, 02:29:34 pm
content: Hi. First post.Does anybody have reference to and point me in the right direction of a small Pcb which will fire a 1400w vacuum motor once the power tool trigger is operated from the power take off socket.The board is messing about in that when switched to current sensing mode, operation of the tool causes the motor to cycle on/off rapidly. The voltage coming off the board is cycling on and off.In normal mode, the vacuum starts and runs fine - no cycling. Motor is fine.Thanks..
Cushman CE-5 Filter and Power Supply Board Repair  - Page 1
Forum section: electronics / repair

author: DaneH3
author_rank: Contributor
timestamp: October 15, 2020, 04:35:10 am
content: I made another post about this Communications Monitor at one point, but I am now creating a new thread for a new problem since I've done a lot since then.For context, I am repairing a Cushman CE-5 Communications Analyzer that has working standby power but does not run otherwise once turned on.I narrowed the issues down to the power delivery boards, A12 and A13 that are responsible for rectification, filtering, and regulation of the three voltage busses. +20V, +5V, and -12V.When first testing the machine before I replaced any components, both the +20V and +5V busses coming from A12 were outputting roughly 0V. The -12V buss was showing the appropriate voltage.I have since replaced ALL of the electrolytic capacitors on both A12 and A13. This brought back power to the +20V buss which is now showing the correct voltage.There is still no +5V buss voltage (0V)Starting from the top, the AC voltages coming from the transformer were within specifications before they enter the A13 rectifier and filter board. The voltages coming from A13 are all within ±0.5V of their required voltage butpin 5 of A13 shows +13.3V, but should be +17.5V. Does this imply that some of the rectifier diodes are bad?So my questions boil down to:- Should I try replacing the rectifier diodes on A13 to see if that brings the +17.5V DC output back up to spec?- Would the out of spec voltage for pin 5 on A13 cause the +5V buss to lose output?- What should I try troubleshooting/checking on A12 to try and figure out how to restore the +5V buss?Thanks in advance!I don't have much experience with voltage regulators, and this one is even more foreign to me due to its age.I have attached all of the related schematics. The entire manual can be found athttps://bama.edebris.com/download/cushman/ce5/ce5-1973.pdfas well.

author: bob91343
author_rank: Super Contributor
timestamp: October 15, 2020, 05:40:13 am
content: CR5 might be shorted. Or CR4.

author: DaneH3
author_rank: Contributor
timestamp: October 15, 2020, 05:56:11 am
content: Quote from: bob91343 on October 15, 2020, 05:40:13 amWhat might be the best way to test CR5 and CR4 in-circuit?

author: bob91343
author_rank: Super Contributor
timestamp: October 15, 2020, 10:15:56 pm
content: If they are shorted you will measure short with an ohmmeter, in or out of circuit.
Custom Probe for MI Model 904 Gaussmeter - Page 1
Forum section: electronics / repair

author: enut11
author_rank: Super Contributor
timestamp: June 07, 2020, 08:28:47 pm
content: I have a Magnetic Instrumentation (MI) model 904 Gaussmeter that came without a probe and would like to get it working.Have not been able to find any info or manual online.I believe this type of instrument uses a Hall Effect chip. These chips normally have 3 pins: power, ground and output.You can see from the photos that the probe socket has 4 wires so maybe the fourth is a shield.Our local supplier (Jaycar) has a UGN3503U sensor that I will try. It needs a nominal 5v supply.Ebay has the following linear chips on offer:https://www.ebay.com.au/itm/10-PCS-AH49E-TO-92S-AH-49E-LINEAR-HALL-EFFECT-IC/122490059728https://www.ebay.com.au/itm/4PCS-HAL401SF-A-Encapsulation-SOT89-3-Linear-Hall-Effect-Sensor-IC/372247259357I have never used a Hall chip so any feedback from the Forum would be appreciated.**NOTE: This thread is now in the PROJECTS section **
Cutting out laptop HP. - Page 1
Forum section: electronics / repair

author: cleanworkbench
author_rank: Regular Contributor
timestamp: August 30, 2020, 07:34:51 pm
content: The laptop has had a new rechargeable pack , it went to 100% a few times but over a short period just wouldnt seem to hold a charge , just plain shut off.Any issues with a HP 6735s charging ?.If the laptop has,nt been cleaned of dust is it prone to overheating and thermally tripping off ?.Any info appreciatedThanks

author: wraper
author_rank: Unknown
timestamp: August 30, 2020, 07:48:41 pm
content: You "new" battery is a recycled crap with controller which was reset.

author: TheMG
author_rank: Frequent Contributor
timestamp: September 01, 2020, 03:41:32 pm
content: Is the "new" battery pack a new genuine HP replacement from a reputable source? Or is it some cheap 3rd-party replacement from an unknown source (eBay, Amazon, or similar)?
CW2500 epoxy discontinued - best replacement? - Page 1
Forum section: electronics / repair

author: Peacefrog
author_rank: Contributor
timestamp: June 19, 2025, 05:02:54 am
content: I have previously used the Chemtronics CW2500 epoxy to repair lifted traces, but was surprised just now to find it has been discontinued. Has anyone found a suitable replacement? The advantage of CW2500 was always held to be that it could withstand high temperatures. Thanks!
CyberHome CH-DVD 300 DVD player no power repair - Page 1
Forum section: electronics / repair

author: poot36
author_rank: Frequent Contributor
timestamp: December 04, 2021, 10:20:25 pm
content: Lets take a look at why it will not power on.Outside pictures attached.

author: poot36
author_rank: Frequent Contributor
timestamp: December 04, 2021, 10:22:04 pm
content: Inside pictures, can you spot the issue yet?

author: poot36
author_rank: Frequent Contributor
timestamp: December 04, 2021, 10:22:50 pm
content: Power supply board.

author: poot36
author_rank: Frequent Contributor
timestamp: December 04, 2021, 10:24:52 pm
content: Lets replace that bad cap, and the tester says... bad.Replacement cap in second picture.

author: poot36
author_rank: Frequent Contributor
timestamp: December 04, 2021, 10:25:38 pm
content: All working now. Green power light it a bit hard to see. The bad cap was on the 5V rail that was also part of the feedback section of the power supply so no wonder it would not power up. This unit takes a 12V and 5V rail to operate.

author: CaptDon
author_rank: Super Contributor
timestamp: December 05, 2021, 04:26:52 am
content: That sure was a shit load of pictures and posts just to see a bulging bad capacitor? I own two of these both with the same identical problem. It is a pain in the ass to get them to open the tray if they sit a few days!! I found that leaving a worthless CDR in the tray when not using the unit seems to help. They are VERY unique because there is a super simple button press hack that makes them 'region free'!!! That is why I own two!!

author: poot36
author_rank: Frequent Contributor
timestamp: December 06, 2021, 12:25:02 am
content: It also has a serial port but I am not sure what it does as this was a friends unit and I was only asked to fix it not turning on.
CyberPower 1500VA UPS Conductive glue, - Page 1
Forum section: electronics / repair

author: CaptDon
author_rank: Super Contributor
timestamp: May 04, 2025, 07:45:04 pm
content: I have a 1500VA UPS which usually sits dormant and unplugged. I plug it in to charge for a day about once a month. Its main use is for power when I go to hamfests in the sell mode to be able to power up my equipment for sale. Lately it has been making that 'Hot Electronics' smell. I decided to have a look. There were several gobs of the rubberized glue that turns conductive and sure enough there was a chunk that had burned and was making sparks. It was conducting from what looked like line voltage sensing resistors to a grounded pin of an opto-isolator. Glad I caught it before the unit got wrecked!!! I like this unit because it will 'black start', no need for previous line input!! I also shot the 12VDC fan with some WD-40 to stop the fan from 'chirping'. Cheers mates!!
CyberPower UPS Capacitor Replacements - Page 1
Forum section: electronics / repair

author: ParadiseStudios
author_rank: Newbie
timestamp: July 17, 2019, 09:14:19 pm
content: https://www.eevblog.com/forum/beginners/aftermarket-ups-replacement-batteries-are-they-worth-it/I've followed the topic above and received help from the posters so I decided to include it in this post as a reference. I'm mainly including this here for other people searching the internet so they can find it and find help also. I'm also hoping some experts here can weigh in on some insights they might have in relation to both soldering components and repairing UPS units.I've had a couple CyberPower 1350AVRLCD UPS battery backups for around 7 years. I should have replaced the batteries earlier in their life but instead I let them degrade and die. They got to the point where they would shut the computer down while the electricity was still on. After much research, I decided to purchase a CP1290 from PowerSonic. I replaced the batteries in one unit and it beeped when I turned it on without AC power. I turned it back off and decided to try it in an outlet. When I plugged it into the wall, it sizzled inside and puffed out a lot of smoke. I opened it up completely to see 2 blown capacitors on the board. I was informed that the caps were likely toasted before I plugged it in. "During the time frame that the unit was inoperable it had cooled down and when I plugged it into electricity with not fully charged accumulators, they got loaded and overheated rapidly, releasing pressure and gases." So assuming that was the reason and I didn't purchase the wrong batteries, I am replacing the bad caps and an IC chip, as per suggestion by another forum. I will also be replacing the same components in my second unit before replacing the batteries, assuming I can handle the soldering jobs.Here are the parts that I will be replacing. Is there a specific way the Viper22 goes on the board, like the capacitors do? Does anyone know anything about accumulators? After replacing the parts below will it be safe to plug this thing in to AC power? How would one go about charging accumulators? Leaving the batteries inside for a day or 2 before plugging it in? Maybe with the new parts inside everything will work as it is supposed to but I'll be plugging into power outdoors and watching it closely for a while before bringing it into my house.https://www.digikey.com/product-detail/en/nichicon/ULD1H220MDD1TD/493-16251-1-ND/7365024C1https://www.digikey.com/product-detail/en/nichicon/UCY2D330MPD1TD/493-4806-1-ND/3129143C3 & C6https://www.digikey.com/product-detail/en/stmicroelectronics/VIPER22ADIP-E/497-7694-5-ND/1852690Viper22Thank you for letting me post this here, I appreciate the helpful knowledge I have acquired thus far.
Cyberpower UPS CP1500EPFCLCD repair - Page 1
Forum section: electronics / repair

author: Simonv92
author_rank: Newbie
timestamp: April 10, 2024, 04:46:08 pm
content: Hi all!I have a Cyberpower ups CP1500EPFCLCD (europe version) with a damaged cpu (probabily after some problems with the usb com port).The cpu on the board is an ST STM32F102C8T6, but I don't have the source code to program a new one.There's a way to obtain the binary code for the cpu? Or does any one of you have one unit to read the code?Thank you very much!Best regardsSimone

author: coromonadalix
author_rank: Super Contributor
timestamp: April 10, 2024, 10:14:27 pm
content: it depends if someone has the same ups and can or could read the mcu if it is not locked from being readand for sure you will never get a source codeyour chances are pretty much zero at this point, only time will tell

author: fmashockie
author_rank: Frequent Contributor
timestamp: April 11, 2024, 01:13:20 pm
content: What do you mean the CPU is damaged? I think what you're asking is, is it possible to flash the chip - flashing is the process of reading a programmed microcontroller (MCU) and taking that programming code to program another MCU. The STM32 series is typically pretty easy to flash. There are a lot of resources on how to do it. Of course as long as it is not read-protected. You won't know until you try (unless someone else has already tried with this make/model UPS).I ask what you mean by damage because it is still possible to flash a faulty MCU depending on where the fault is. For example, I've flashed MCUs successfully that have a couple bad IO pins. But obviously if the whole chip is dead, you're not going to be able to perform this procedure.Here's a video I did on flashing a STM32 series MCU utilized in the APC BR1500G UPS. I go through how to flash the MCU using STM's free software and a UART-USB cable. As you can see, APC did not read-protect their MCUs for this model UPS. You'd be surprised how many companies don't. Good luck!

author: coromonadalix
author_rank: Super Contributor
timestamp: April 11, 2024, 02:14:00 pm
content: oh if they haven't locked it good for the OPjust grab a cheap programmer interface and maybe in time, someone may or will post the mcu content ...
D882 NPN Transistors Keep Burning After Motor Replace - Page 1
Forum section: electronics / repair

author: FShahid
author_rank: Newbie
timestamp: September 17, 2019, 08:21:26 am
content: Hi everyone, this is my first post here. Previously I been on badcaps forum for computer-related repairs.I have a rechargeable dc fan which runs on 12V Lead-Acid battery. It has been running great for last 4 years until recently when the motor went dead.I think when motor died it put load on two D882P NPN transistors and fried it. The person who was using it told me that fan started making noises and was slowing down and smell starts to come.Upon opening and inspection of the motor it is found that both carbon brushes were gone, so I went ahead to find replacement motor in the market.However I searched each and every shop but couldn't find exact replacement one, possibly due to the voltage rating and the shape of motor.Somebody then searched in shop and gave me similar replacement motor, slightly shorter (about 1 cm) but same diameter motor.I bought it and also bought four D882 NPN transistors (extra 2 just in case). Upon replacing and installing the motor I tested it. The fan has three speeds. The fan started working for like half a minute and the speed was adjustable too but after some time within a minute the smoke starts coming out of the replaced D882 transistors. I quickly powered it off and inspected it was very very hot, and one of them was completely fried. One thing to note that when it starts to smoke the fan was running at same speed (not ajdustable) no matter what speed I select so I guess the transistor was fried by then. I replaced the fried one with another transistor and same thing, it worked fine for half a minute (with speed adjustable) then start heating up rapidly that it smoked.I guess the seller gave me motor that is meant to work at lower voltages which is why at 12V it is taking more current than the transistor can handle.So if anyone could suggest what replacement NPN transistors I shall buy next so that it can handle the new motor load. I'm thinking TIP141 can work but not so expert in electronics...Datasheet for D882:https://www.st.com/resource/en/datasheet/2sd882.pdf(The original one in rechargeable fan was D882P and the replacement I got is NEC D882)Datasheet for TIP141 which I think can work but then the DC Current Gain difference is too much:https://www.onsemi.com/pub/Collateral/TIP140-D.PDF
DAB water pump inverter repair - Page 1
Forum section: electronics / repair

author: bogdan2014
author_rank: Regular Contributor
timestamp: July 05, 2019, 12:12:38 pm
content: Greetings,I'm trying to repair a DAB "esybox" water pump that shows an error which according to the manual is indicating one of the following issues:- blocked motor (excluded)- fault on the IGBT drivers or final stage- firmware problem- output current reading circuit issues (soldering joints, components etc)According to the owner, the pump stopped working after the mains supply went down for a while.I started by checking the transistors and the gate driving portion up to the gate drivers (IRS21084). Apart from a strange diode configuration, everything seems ok.The current measuring section is done with 0.1ohm resistors and what seems to be LM393 comparators. The resistors are fine.I'm tempted to replace the driver ICs since there's no way of checking them anyway, and those are the most sensitive parts out there. But I want to eliminate anything else as much as possible.
Daewoo AKF–4306W or Korean Electronics Corp KCC–607V Tuner Module Data Wanted! - Page 1
Forum section: electronics / repair

author: Chris56000
author_rank: Frequent Contributor
timestamp: November 15, 2024, 01:22:33 pm
content: Hi!Can any of our Chinese or South Korean friends help me with a datasheet for a KEC "KCC–607V" AM/FM Tuner Module OR provide me with a schematic for the Daewoo AKF–4306W car radio that I believe uses this module please?. . .I need the information to help repair a Lin Classik/230 Mark I (NOT the "Knect" versions!) with no f.m., and Linn are absolutely snotty about giving any sort of help, let alone circuit or other technical data – they don't even put specifications in the Owner's Booklet!Chris Williams. . .PS!. . .One in Chinese or Korean will do as I can OCR and translate it!
Daewoo VCR / DVD combo not loading tape. - Page 1
Forum section: electronics / repair

author: DaveMX5mk1
author_rank: Contributor
timestamp: March 06, 2021, 12:38:20 pm
content: Hi, I have a Daewoo DF--4700P VCR / DVD recorder.I haven't used it for a while but wanted to transfer some old VHS tapes to DVD. It worked okay to start with but now when I put a tape in it dosen't load. The load motor dosen't turn at all. If I push the eject button again nothing happens and I have to take the cover off the unit and manualy wind the mechanism back to get the tape out. When a tape is inserted after about 5 seconds the display says ERR and the unit switches off.The motor itself is working as if I put on an external supply ( having dissconected the cable to it ) it drives normaly.The power supply outputs look fine except the +14 volt supply is at 16 volts but as this is a unregulated suppley with only 1 diode and capacitor in it I think this must be normal.I've cleaned and checked the mode switch as much as I can and the four switched outputs go between 0 and 5 volts as the switch is turned.The service manual says to check for 5 volts on pin 63 of IC501 which is the load motor control signal and I'm only getting 0.5 volts here. If this is missing it says to check the 14 volt supply and D825, which is the rectifier diode for the 14 volt supply, and this seems okay as stated above apart from being 16 volts. The manual gives no other information as to what to do if this 5 volts is missing. I don't know if the output of pin 63 is truely an output or if it switches to ground and the voltage is coming from the deck. The 14 volt supply mentioned above goes to the deck. I can't find a circuit diagram of the deck so I'm not sure whats going on in there.The drum motor and spindle motor both turn when the unit is switched on so I guess these are working.I've inspected the cassette deck and can see no sign of damage. I think it is some form of T-MECHA deck.Has anyone any ideas as to what else I could try?The unit seems to be electricaly the same as a Sanyo HVR-DX625 if that helps.Thanks for looking.Dave.( in the UK )
Daikin AC remote screen fades out. Not weak batteries. - Page 1
Forum section: electronics / repair

author: wilfred
author_rank: Super Contributor
timestamp: May 24, 2025, 04:42:54 am
content: I have an AC remote that suddenly is unable to show a full screen of segments. I tried new batteries and even connecting a power supply. I found two pads accessible from the battery compartment labelled "reset". I tried shorting them with and without power connected but nothing changed.When I insert batteries after power has been disconnected for about 30 seconds and for about 1/4 second the display tries to light up but it never manages the whole display and fades away within a second or two.The timing of it made me think a capacitor is involved since it fades out the display. But also it isn't an even fade out uniformly across the entire display. The only non surface mount capacitor is the 100uf electro on the rear of the PCB. I removed it and it measures spot on but I still replaced it.It's weird and I will get a universal replacement, but I'm still curious about it.

author: Whales
author_rank: Super Contributor
timestamp: May 24, 2025, 07:15:26 am
content: Dirty contact between PCB and LCD, supposed to be resistive but is now capacitive?

author: wilfred
author_rank: Super Contributor
timestamp: May 25, 2025, 01:49:56 am
content: Quote from: Whales on May 24, 2025, 07:15:26 amI thought that and separated it. It was well stuck to the PCB. But a day later without power I replaced the batteries just to verify the current status before removing the LCD to clean the contacts. It now seems to work. If it fails again I'll get in and give the contacts a clean.My motto is "Don't die wondering" but I may have to. It has always had batteries fitted except for the brief period to replace them.

author: BradC
author_rank: Super Contributor
timestamp: May 25, 2025, 02:32:31 am
content: If the LCD is "fading out" perhaps the processor is turning on some segments then ceasing to function. LCDs get funky when subjected to DC. Intermittent crystal or something?

author: wilfred
author_rank: Super Contributor
timestamp: May 25, 2025, 09:46:06 am
content: Quote from: BradC on May 25, 2025, 02:32:31 amIt really does look like the processor tries to startup and fails.I tried looking again for others experiences. I did find this video. I don't recommend watching it, but basically it shows a similar fault and replacing the crystal But it also shows cleaning the PCB including the LCD contact area. So it is hard to say which was the solution.I have a crystals somewhere so I will try this when I find them and if the remote stops working again. Which I expect it to since I haven't done either yet.