hybridfree/eevblog-posts huggingface dataset:
Monitor not working - but screen undamaged - Page 1
Forum section: electronics / repair

author: Jungle-Jim
author_rank: Newbie
timestamp: February 03, 2022, 02:05:47 pm
content: Hi all(my first post here)I have a recent model Benq 32" monitor (PD3200U-T) - which is not working.* It is not totally dead - lights come on when you switch it on. There is no start-up display, or menuing etc - it is blank - but I think the backlight is working - eg the screen has a glow - like a normal screen when it's displaying black, but there is some backlight light glow coming through.* The screen itself is not damaged (the unit has no blemishes at all).* When the monitor starts, it doesn't display any sort of startup screen or menu (just that black screen with a faint glow from backlight). But pressing the menuing buttons on the front, it would appear that they still trigger something - such as the backlight going off and on and LEDs flashing on or off (even though nothing is displayed).* Nothing happens if connected via HDMI to devices.* All the electrolytic capacitors test ok (removed from the PCB).* No component on the two boards inside it look cooked or damaged, and there aren't any burning smells when it's on (or sounds eg noisy caps etc).Any suggestions of where to start, or previous experience which can point to solutions would be greatly appreciated.Thanks

author: abdulbadii
author_rank: Frequent Contributor
timestamp: February 04, 2022, 12:06:29 am
content: picturing it up hereMight be before T-CON which being fed by, i.e. video process circuit

author: TheMG
author_rank: Frequent Contributor
timestamp: February 04, 2022, 01:21:48 am
content: Like most monitors these days the main board is pretty much a one-chip solution, the processor/controller, video processing, I/O, and LVDS output to the TCON board are all from the same chip.Quote from: Jungle-Jim on February 03, 2022, 02:05:47 pmDo you mean if you plug the monitor in to a PC via HDMI, the PC does not properly detect the monitor? You would obviously need a PC with a second monitor or built-in display like a laptop to be able to see if it's properly detected or not.
Monitor Power Repair - Advise needed - Page 1
Forum section: electronics / repair

author: ohms law
author_rank: Contributor
timestamp: June 23, 2021, 10:48:05 pm
content: Good day all,I need the power of the collective internet to help me identify the best approach to fixing my Monitor.Problem this morning turned on the monitor it came on was dark and then screen was black - sound works fine as well as the PC know's it's there. I have 2 monitors connected to my PC.My Philips BDM 4065UC was flickered a few times before turning on.1.) Does anyone have a schematic for a 715G6985-P01-000-002R2.) anyone know what the common causes of this type of failurethanks in advance

author: bob91343
author_rank: Super Contributor
timestamp: June 23, 2021, 10:53:27 pm
content: Always test the power supply first.

author: Manul
author_rank: Super Contributor
timestamp: June 23, 2021, 11:17:13 pm
content: Also test if there is really no picture or just the backlight is not working, aka flashlight test.

author: ohms law
author_rank: Contributor
timestamp: June 23, 2021, 11:19:46 pm
content: The Logo comes on so there is picture - the logo is very dark howeverit's as if the backlight driver has failed now not sure where that would be and how to test that properly

author: Manul
author_rank: Super Contributor
timestamp: June 23, 2021, 11:30:51 pm
content: On the top left corner of your first picture where "RoHS" logo is.

author: shakalnokturn
author_rank: Super Contributor
timestamp: June 24, 2021, 07:48:56 am
content: Check for voltage on the LED supply as mentioned by Manul.Often a single defective LED is the cause.A megohmmeter or any supply with enough voltage and current limiting can be used for a quick LED string check. You must get the polarity right first time though.

author: Manul
author_rank: Super Contributor
timestamp: June 24, 2021, 12:37:35 pm
content: As shakalnokturn said, it is probably LED failure. You can measure ouput voltage (if I read correctly from picture it is marked +VLED and -VLED). Measure with backlight connector connected and then disconnected. If the voltages measured are very similar, that probably means that the LED strip is open circuit (could also be PSU failure, but unlikely). If the voltage is zero then it means PSU failed, LED strip is shorted or it could be a fuse (I see a fuse in the picture, presumably for backlight power output, small rectangular soldered on the board).Hope this helps to get started, but be careful of high voltages and don't harm yourself. Backlight voltage could be quite high, not to mention the main bulk capacitor of the PSU.
Monitor vertical shake - Page 1
Forum section: electronics / repair

author: Variuls
author_rank: Newbie
timestamp: June 07, 2020, 11:39:45 pm
content: Hi.I have one problem with my monitor (Philips).One video with problem:The monitor has fault with and without input signal.The problem is not immediate, it happens after being turned on for a few minutes.The power supply is discarded, it is external (19v 2.3A) and I have replaced it with other.I have replaced the large 47uF 100V electrolytic capacitor, but the same is still happening.A photo of the PCB:https://subefotos.com/ver/?0bafd4332447948890f5ccb1779ba46do.jpg
monitor wont turn on - Page 1
Forum section: electronics / repair

author: loordgek
author_rank: Contributor
timestamp: January 13, 2022, 08:41:42 pm
content: hii have a monitor that wont turn on i forgot the brand and model but i have the mainboard(sl-dvi-1004)i found out when i bridge source to drain on q2(P3098L top right) it turns on and i can turn it off witch the power button

author: loordgek
author_rank: Contributor
timestamp: January 14, 2022, 01:25:31 pm
content: brand: general touchmodel: rtl224when i disconect the lvds cable from the mainboard the backlight comes oni tried a panel swap with a aser al2216wthe panel from general touch works in the aser
Monochrome LCD Character Display Identification (Buffalo Terrastation) - Page 1
Forum section: electronics / repair

author: Mikek400
author_rank: Regular Contributor
timestamp: December 31, 2023, 07:13:15 pm
content: Happy New Year to Everyone!Have an LCD display that isn't working from a Buffalo Terra Station.My first guess is the LCD need replacement. Not being super familiar with LCD displays I'm reaching out too see if anyone can help.It is a 7 wire connection over a flat-flex connection. Not really sure if it is dot matrix or character.. It also lacks a reflector in the back because it is backlit.It has the markings 1B14C on the flat-flex but doesn't seem to give any meaningful results upon searching.I have attached pictures of the LCD below.I also attached a picture I found of a working one online if that helps any.Thanks in advance.

author: inse
author_rank: Super Contributor
timestamp: December 31, 2023, 08:18:49 pm
content: It’s a character display, you can see the separate blocks.7 wires is too less for standard 4bit interface, I assume it’s SPI

author: amyk
author_rank: Super Contributor
timestamp: December 31, 2023, 10:23:30 pm
content: That's a COG 16x2 character LCD, serial interface - either I2C or SPI. You'll have to analyse the circuit to determine the pinout.I could find 6 and 8 pin models, but haven't seen a 7-pin so far. Example:https://newhavendisplay.com/2x16-character-cog-lcd-fstn-display-with-no-backlight-3v/
MONTRE AMAZFIT, AIDE - Page 1
Forum section: electronics / repair

author: lionelkjh
author_rank: Frequent Contributor
timestamp: July 14, 2025, 01:15:37 pm
content: Hello; I have a broken AMAZFIT smartwatch; I can't turn it on and I have to use the charging base to start it.... Once removed from the charging base, it stops instantly.... When I put it back, the AMAZFIT logo appears and the time appears on the screen but I can't do anything more... I don't know how to factory reset it, and that's what I would need to do to repair it.... Does anyone know how to do this?? Thanks for your help

author: Haenk
author_rank: Super Contributor
timestamp: July 15, 2025, 06:29:17 am
content: Sounds like a dead battery (probably LithiumIon pouch).
More questions about a Tektronix TDS5054B scope - Page 1
Forum section: electronics / repair

author: acheaile
author_rank: Newbie
timestamp: January 02, 2022, 07:28:39 pm
content: Hi everyone,Compared to various photos over the web, i found my TDS5054B lcd screen to be off centered. It is the case at all time it seems (in bios, win2k boot splash screen & in windows/Tekscope application). If i connect an external monitor into the PC Interface board "scope only VGA out", it will be off centered also. But since on such monitor we can make adjustment via the OSD, if i change the horizontal position 7 pixels to the left, it looks perfect.I'm was wondering if it's possible to make those kind of adjustment on the scope itself. Also, on page 6-66 of the service manual they talk about TP1102 on the PC Interface board which would reset the 69000 video adapter. Does anyone experimented with this?Another thing also, i've tried to put 2GB RAM dual channel (2x 1GB) since i have some sleeping in a box. The scope would then boot perfectly, but the Tekscope application will crash in less than 5 minutes, telling about an Unrecoverable system error and need to restart the computer. A common error message it seems that other people already took a snapshot of it. I just put back the original 512MB RAM stick in place and everything is back to normal.Any ideas?Thanks!

author: acheaile
author_rank: Newbie
timestamp: January 04, 2022, 12:43:33 am
content: Replying to myself,The issue with the lcd screen that was off-center is now resolved. I did not figure out what was wrong exactly, but i took the time to pull out the display assembly of the scope and taking apart its components, and i even went to test the ccfl backlight to see if the 2 tubes were working alright (they was). Probably it was that cable that connect from the display interface board to the screen that would not be properly seated.. It was a great surprise after reassembling to see the display now perfectly aligned, and the colors seems more punchy also.Now for the dual channel memory, i think i should try it with a different cpu. The celeron with a 400mhz fsb is probably not a good match with dual channel system ram. I just cant remember....
More SMD identification fun! - Page 1
Forum section: electronics / repair

author: EHT
author_rank: Frequent Contributor
timestamp: September 05, 2025, 09:21:43 pm
content: Hello All!I'm trying to debug a dead board which has many voltage conversions. I'm looking for a switcher which may be taking 48V DC and down converting it to 5-12V or so. I can see the 48V coming in, but rest of the board is not showing DC voltage. In the process of working this out, I'm trying to indentify the main components. I've tested obvious ones (diodes, MOSFETs etc, and can't see anything obvious).So I have these two 8-pin SMD ICs shown in the same pic. Drawn a blank with Google and SMD websites it finds, so asking the expertsMarking "D4412 952A3" - just the one and it's close to where I can find the 48V. Suspect this is a switching IC. Possible this marking is 04412, see pic.Marking "01YK SAYA" - there are many of these, maybe an opto-isolatorThe only component I can find which doesn't look good is the 1FD memory backup capacitor which is showing some leaking.I was hoping one of the SMD sites would filter on the case type, which is the one definite thing!TiaChris

author: EHT
author_rank: Frequent Contributor
timestamp: September 05, 2025, 10:26:09 pm
content: Aha, "SAYA" looks like the code forTI LM5008Abuck converter!.. and D4412 maybe DS4412 which is an I2C DAC by Analog Devices - herehttps://www.analog.com/media/en/technical-documentation/data-sheets/DS4412.pdfThis would mean there are indeed loads of voltage conversions going on ...Claude found me the above!

author: fzabkar
author_rank: Super Contributor
timestamp: September 05, 2025, 11:28:10 pm
content: Quote from: EHT on September 05, 2025, 09:21:43 pmhttp://markingcodes.com/search/c/saya

author: EHT
author_rank: Frequent Contributor
timestamp: September 05, 2025, 11:32:00 pm
content: Great, thanks, that is better than the ones I found. On the other hand once i thought of asking Claude, it got both of these.
Mosfet  - Page 1
Forum section: electronics / repair

author: Eg3300401
author_rank: Contributor
timestamp: January 06, 2023, 12:44:29 am
content: Where can I buy this gpu mosfet

author: fzabkar
author_rank: Super Contributor
timestamp: January 06, 2023, 01:01:25 am
content: https://www.mouser.com/c/?q=CSD95481RWJDatasheet:https://www.ti.com/lit/gpn/csd95481rwj

author: Eg3300401
author_rank: Contributor
timestamp: January 06, 2023, 01:04:37 am
content: That's what I found when I looked it up, but will it work on a gpu?

author: fzabkar
author_rank: Super Contributor
timestamp: January 06, 2023, 01:26:25 am
content: Isn't it the same part?

author: Eg3300401
author_rank: Contributor
timestamp: January 06, 2023, 01:49:39 am
content: It's a different model I think because the one on the gpu is 95481rwj ti 05j p8f2

author: fzabkar
author_rank: Super Contributor
timestamp: January 06, 2023, 02:13:45 am
content: https://www.aliexpress.com/item/1005004118509582.html

author: Eg3300401
author_rank: Contributor
timestamp: January 06, 2023, 02:26:52 am
content: Thank you

author: coromonadalix
author_rank: Super Contributor
timestamp: January 06, 2023, 03:26:30 am
content: you pay 8 times its value ??https://www.ti.com/product/CSD95481RWJ/part-details/CSD95481RWJ?HQS=ocb-tistore-invf-dsrdinvf_prog_invf-invf-store-EDS-euhttps://www.electronicspecifier.com/product-centre/manufacturers/texas-instruments/part/59c8cf905a8ec97a5e8b515d

author: fzabkar
author_rank: Super Contributor
timestamp: January 06, 2023, 03:47:07 am
content: Quote from: coromonadalix on January 06, 2023, 03:26:30 amI only used that link to show the OP that the part was indeed the same.Edit:https://www.ti.com/packaging/docs/partlookup.tsp
Mosfet - Page 1
Forum section: electronics / repair

author: jmelect
author_rank: Newbie
timestamp: February 16, 2023, 06:15:29 am
content: Dear Members,I'm trying to repair a SMPS for a motor drive machine. The circuit uses a mosgate IC IR2110 driving a SPP17N80C3. I'm having problems with ringing on the chip and the mosfet. Is it possible that the noise is coming from installing a machined IC socket? The original design didn't use IC sockets. I'm using the IC socket to make the repair easier however if removing the IC socketwill reducethe parasitic and ringing noise I will try it.Thanks in advance.Jeff M.

author: wasedadoc
author_rank: Super Contributor
timestamp: February 16, 2023, 09:09:11 am
content: IMHO a chip socket, machined or otherwise, is unlikely to cause noise of that magnitude.
Mosfet identify help - Page 1
Forum section: electronics / repair

author: Jetbattalion
author_rank: Newbie
timestamp: July 12, 2024, 04:48:29 pm
content: Please help me identify this tv SAMSUNG 34-Inch SJ55W Ultrawide Gaming Monitor

author: fzabkar
author_rank: Super Contributor
timestamp: July 12, 2024, 05:25:47 pm
content: SY8286A, Silergy, 6A, 23V Input Synchronous Step Down Regulator, marking AWRxyz, QFN3×3-20:https://www.bulcomp-eng.com/datasheet/SY8286A%20(QFN20)%20-%20Datasheet%201.pdfhttps://uploadcdn.oneyac.com/attachments/userfile/53/35/1596012092177_3811.pdf

author: Jetbattalion
author_rank: Newbie
timestamp: July 12, 2024, 05:28:37 pm
content: Amazing work thank you ♥️
MOSFET multi-meter test accuracy - Page 1
Forum section: electronics / repair

author: mikec
author_rank: Contributor
timestamp: November 20, 2020, 01:16:48 pm
content: Hi,There are a couple of standard tests for MOSTFETs that use a multi-meter. For example:Using the multi-meter in DIODE test, turn on the MOSFET and measure the drain-source resistance. Turn of the MOSFET by shorting gate-source and measure drain-source resistance again.Other tests are generally checks for shorts/opens check body-diode etc, the first test above however seems to cover the actual functionality of the MOSFET.My question is using the test above if I verify that the MOSFET actually switches ON and OFF (and other basic tests like body-diode ok), can I conclude that the MOSFET in any switching application is OK and should be discounted as the problem in a faulty circuit/device?I currently repairing a circuit with 8 K2837 power MOSFETs (Transformer coupled Gate Drive circuit for an Inverter welder), 4 MOSFETs are split into 2 pair (paralled) for the HIGH-SIDE and the remaining 4 are split into 2 pair for the LOW-SIDE switching. At the moment I suspected a short-circuit is occurring at some point in the switching cycle (i.e. related to the MOSFETs), the control circuit seems to shut down and restart. Instead of probing the MOSFETs, I went with using my FLIR camera to watch the heating of the MOSFETs (didn't feel like probing the high-voltage circuits) and this did seem to point to unexpected behavior. 1 pair of the HIGH-SIDE got warm and the other pair didn't warm up, on the LOW-SIDE only 1 MOSFET of each pair warmed-up.I may have convinced myself from the thermal image that the MOSFETs must be damaged in someway and the basic MOSFET test above can't detect the issue. I am wondering are there some important measurements of the MOSFET for this particular application that are missed by the basic MOSFET test?

author: Manul
author_rank: Super Contributor
timestamp: November 20, 2020, 01:39:58 pm
content: If all mosfets are measured to switch correctly with a test circuit and multimeter, I would say it is unlikely, that they are the problem. Mainly because in high energy circuits any obscure failure would very likely escalate to catastrophic. You can not conclude this, but you can guess with high probability.I would suspect driver problem, possible shoot-through or some other problems down the line.

author: mikec
author_rank: Contributor
timestamp: November 20, 2020, 05:58:49 pm
content: Yes, I had kinda figured it was unlikely a failure that leads to something catastrophic, its just enough to pull the power down on the control and drive circuits.The shoot-through would be where a high-side FET has not turned off fully before a low-side FET has turned on, resulting in an almost DC short circuit?I guess in the end the MOSFET tests are pretty decent test, I'll assume for now MOSFETs are good and take a look at the drive circuits (which so far are looking pretty alright as well)
MOSFET Replacement - Page 1
Forum section: electronics / repair

author: TobyH
author_rank: Newbie
timestamp: May 31, 2019, 05:40:12 pm
content: Hi all, new member here, Please be gentleI am looking to repair a seat motor driver from my car. I've determined that two of the MOSFETs have died. I've been hunting around using the datasheet but just can't seem to find anything similar. The originals are now obsolete (the car is 19 years old!). Could anyone perhaps point me to something suitable that could be used?Original MOSFETs are Fairchild RF1S25N06SM (TO-263AB package). I have attached the datasheet if it helps (and if it works!)Any help is much appreciated. Thanks
Mosfet replacement, PJA138K vs compatbility with similar ones - Page 1
Forum section: electronics / repair

author: RayRay
author_rank: Frequent Contributor
timestamp: October 17, 2023, 08:23:53 pm
content: Hey Guys. I need to replace a faulty mosfet (PJA138K) that said, it'd take me less time to obtain BSS138Q or BSS138L instead.The question is, whether they're interchangable with the original or not. The datasheets are quite similar, but not entirely identical, so I just wanna make sure. I could still get PJA138K if it's a must, but it'd just take me longer to do so.Here are the datasheets for all 3:https://www.panjit.com.tw/upload/datasheet/PJA138K.pdfhttps://www.diodes.com/assets/Datasheets/BSS138Q.pdfhttps://www.onsemi.com/pdf/datasheet/bss138lt1-d.pdfWould appreciate your help.

author: tszaboo
author_rank: Super Contributor
timestamp: October 17, 2023, 09:31:25 pm
content: How is it used?

author: RayRay
author_rank: Frequent Contributor
timestamp: October 17, 2023, 09:47:30 pm
content: It's used on a computer monitor's t-con board, outputting to one of the flat cable connectors that goes into the final destination (left/right controller boards, that are attached the lcd itself with COF, chip on film cables). Hope that's sufficient, can't get more descriptive than that.

author: RayRay
author_rank: Frequent Contributor
timestamp: October 17, 2023, 10:07:38 pm
content: What do you think about this one?https://www.diodes.com/assets/Datasheets/DMN53D0LQ.pdfThe specs match the original more closely

author: RayRay
author_rank: Frequent Contributor
timestamp: October 18, 2023, 09:41:01 am
content: Ended up ordering DMN53D0LQ, should be fully compatible if judging by the datasheets.Will update if it worked at a later time
Mosfet went Rocketdyne - HOW TO - Replacing nearby componets that were toasted - Page 1
Forum section: electronics / repair

author: ThermallyFrigid
author_rank: Frequent Contributor
timestamp: January 19, 2022, 01:22:34 pm
content: Hello,I am working on a PCB where an SMD Mosfet burned furiously, taking out a few other nearby very small (maybe 0201) capacitors and very small SMD resistors so there is no hope of identifying them.No schematic is available.Obviously a careful cleaning with 90% alcohol and cotton swabs is a first step, but when that does not reveal any information?My question is what do you normally do in situations like this?Does it take a EE to determine what suitable component goes there? Do you guess? Of course, SMD caps usually have no markings any way and if you're replacing them it may be because they are defective and any readings you get are not necessarily accurate in identifying them anyway. Do you give up?Thanks

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 19, 2022, 02:04:07 pm
content: Easiest: replace board.Medium: replace identifiable components until it works. Mind, you'll need to replaceeverythingthat's toasted; likely the controller is dead, maybe the supply to it as well (sometimes there's an aux supply, as simple as a transistor or two, or as fancy as a whole other controller/regulator). Plus whatever caused this to die, which could be anything from overloaded output to bad electrolytics or tin whiskers. (Most SMPS should tolerate a shorted output, but it's a design issue that's easy enough to overlook.)Hard: trace the circuit, compare with known circuits. Offhand, it looks like it might be a bog standard UC3842 based offline SMPS. I don't get what the two series diodes are doing there, and the driver transistor (likely the resistors and transistor by the gate pin) probably aren't necessary, but eh, it depends, right? Failure could've been various things, including just overheating. '3842 is a current mode controller, safe against overload -- on an immediate (cycle by cycle) basis, but the transistor can still overheat and blow up. It's a control method that solves several ills, but far from every possible one.Tim

author: ThermallyFrigid
author_rank: Frequent Contributor
timestamp: January 20, 2022, 04:29:26 am
content: Quote from: T3sl4co1l on January 19, 2022, 02:04:07 pmExtremely helpful reply.Thank you much !

author: MegaVolt
author_rank: Frequent Contributor
timestamp: January 20, 2022, 01:11:25 pm
content: Quote from: ThermallyFrigid on January 19, 2022, 01:22:34 pmSearch for photos of the working device can help. Internet, forums ...

author: ThermallyFrigid
author_rank: Frequent Contributor
timestamp: January 22, 2022, 02:21:27 am
content: Quote from: MegaVolt on January 20, 2022, 01:11:25 pmThanks.Not only did I find photos....I found a NEW replacement board for about $11.00 delivered.No point in even a attempting repair.
Mosfets on monitor inverter board getting too hot - Page 1
Forum section: electronics / repair

author: Ahura Mazda
author_rank: Contributor
timestamp: May 01, 2021, 12:29:33 pm
content: Hello everybody, I came across one monitor which I was told makes buzzing sounds (for which I assume are inverter transformers), and sometimes wouldn't turn on. I have to say, with monitor working, I couldn't replicate the buzzing sound after replacing the bad caps, practically all of them, but I am worried about dark spots on the board indicating really high mosfet temperatures. After an hour, the enclosed box with the board isextremelyhot to the touch (the reason for bad caps, surely). The board dates back to 2006.I was thinking whether mosfetsQ5andQ6have degraded over time and their internal resistance has increased? Does replacing the mosfets with even lower Rds(on) could solve the issue or could there be another reason for such high temperatures? Could some asymmetry or something else I overlooked?Thank you, any suggestion would be highly appreciated.

author: madires
author_rank: Super Contributor
timestamp: May 01, 2021, 01:49:56 pm
content: MOSFETs can become hot by driving them too slowly, i.e. when they stay longer in the resistive part of their operation curve. You could check the quick-discharge based on Q3 and Q4, and also R11 which limits the drive current.

author: TheMG
author_rank: Frequent Contributor
timestamp: May 02, 2021, 08:01:20 pm
content: I'm guessing that monitor has very high hours of use on it?A lot of older monitors do run quite hot and that's just the way they were designed, to keep the costs down as well as the physical size, so not much in terms of heat dissipation, and that type of PCB material does discolor like that over time with elevated temperatures.Also I believe I read somewhere that as the CCFL lamps age their operating voltage increases slightly, and they run hotter.

author: Ahura Mazda
author_rank: Contributor
timestamp: May 02, 2021, 08:54:11 pm
content: Quote from: TheMG on May 02, 2021, 08:01:20 pmWell, that is interesting, I couldn't find the info regarding the operating votage increase, that is interesting and would explain this if true. And yeah, I'm not sure for hours used, but it is safe to assume so.QuoteMmm, that is true. I don't know how to check for quick discharge, but I did remove the top metal cover which was enclosing the board (literally making it like an oven) and I did use it all day today to see whether buzzing would return. And, the temps now seem quite reasonable. Still fairly hot, yes, but much warmer than before.The main source of temps as I've observed today is the switching transistor on live side. Since the monitor won't be on much daily, I really don't want to bother with making suitable heatsink for it.Thank you for your help.

author: JayArr
author_rank: Contributor
timestamp: May 04, 2021, 05:59:24 am
content: I would replace all four lamps and don't forget the high voltage caps, C13 and C14.
Motherboard 5V rail issue - Page 1
Forum section: electronics / repair

author: bogdan2014
author_rank: Regular Contributor
timestamp: April 07, 2020, 10:18:39 am
content: We have this older computer at work that has a strange issue. When powered up, it doesn't POST or boot, but every LED that lights up "pulses" like the 5V rail was pulled into protection. I have checked it with a multimeter and indeed the voltage drops in cycles, but the other rails are absolutely fine. The power supply does not go into protection itself, it continues to power the rest of the computer (fans and hard drives work). Something probably pulls the rail but not enough to trigger the overcurrent protection. I have replaced the power supply and the same issue occurs.I have eliminated almost everything that might cause an issue outside of the motherboard, even the RAM, I have also replaced some leaky caps. What can I possibly do to salvage it?I would scrap it but it's the only one we have that works in that configuration.

author: Rasz
author_rank: Super Contributor
timestamp: April 07, 2020, 11:52:02 am
content: Quote from: bogdan2014 on April 07, 2020, 10:18:39 amstart with model of the boardremove everything out of the case and plug just the bare minimum
Motherboard - Electronic Behaviour - Page 1
Forum section: electronics / repair

author: gabrimor
author_rank: Newbie
timestamp: November 29, 2020, 01:59:06 am
content: Hi!I Bought a dead motherboard, months ago. It was an Asrock Z77 Extreme 4, which is a high end motherboard.I knew it was defective.Tried to start the motherboard with the motherboard bower button. Nothing happened.Jumped the PSU and the motherboard started.Since this event, the PC works normally.And no, I don't have to jump the psu anymore. Now power button works.An Asrock Z77 Pro 4 from a friend showed the same problem.I tried the same solution.Dice. The motherboard are working again, and he doesn't need to short the psu anymore. It was just one time.What you think about it?For me, it's not something related with chips. Looks like an electronic problem, from a mosfet, a cap...Thank you!

author: retiredfeline
author_rank: Frequent Contributor
timestamp: November 29, 2020, 02:05:15 am
content: Quote from: gabrimor on November 29, 2020, 01:59:06 amYou lucky devils. :+

author: Rasz
author_rank: Super Contributor
timestamp: November 29, 2020, 11:06:42 am
content: probably first steps ofhttps://www.eevblog.com/forum/repair/mainboard-suicide-after-sleep/as described by me inhttps://www.eevblog.com/forum/repair/mainboard-suicide-after-sleep/msg2983902/#msg2983902problems start off with mild symptoms of not wanting to power up, but later turn to power supply starts but nothing happens. Asrock used to RMA those boards without question suggesting they knew exactly where they screwed up.

author: gabrimor
author_rank: Newbie
timestamp: November 29, 2020, 05:10:58 pm
content: Thank you Rasz!I gave a read in your links, ans I think my problem is similar, but maybe, a little different.My friends Z77 Pro 4 is turned on and off many times a day, and, last night, the psu was off the wall.It was off the wall for around 18 hours, and today, turned on normally.Hard to explain, don't you think?Thank you for the support!
Motherboard has no power - Clevo W650SC - Page 1
Forum section: electronics / repair

author: vcolella
author_rank: Newbie
timestamp: April 23, 2024, 06:07:41 pm
content: Hello all,I've been for some time now trying to troubleshoot this Clevo W650SC laptop motherboard. It has no power, no charging lights, nothing. Now please bear in mind I don't have much experience with this stuff, so looking for some info online I decided to search for shorts.Luckily I've managed to find thisservice manual.VIN is not shorted and I'm reasonably convinced of a short on VDD3. I've desoldered most mosfets, disconnected coils and removed some caps without success in pinpointing the faulty component. The lowest resistance I could find was near ME and BIOS ROM (U27, U28), but desoldering these didn't fix the short.Any ideas on how to go forward ? Thanks in advance !

author: amyk
author_rank: Super Contributor
timestamp: April 24, 2024, 04:11:11 am
content: Current-limited power supply and a thermal camera.

author: vcolella
author_rank: Newbie
timestamp: April 24, 2024, 04:27:54 pm
content: Unfortunately a thermal camera is not really an option right now

author: modoran
author_rank: Regular Contributor
timestamp: April 24, 2024, 10:51:38 pm
content: Then use IPA to see what is getting hot. Is not as fast as a thermal camera, but it will din the job.Inject 1V and a lot of amps into the circuit.

author: vcolella
author_rank: Newbie
timestamp: April 25, 2024, 12:21:20 am
content: Alright ! Just ordered a rosin short "detector", will try that as well as IPA. Any suggestions on where to inject the voltage ?

author: amyk
author_rank: Super Contributor
timestamp: April 25, 2024, 04:27:26 am
content: Apply power via VIN, since anywhere else could risk backfeeding and damage (there are often "discharge FETs" used to pull rails to ground quickly if the power sequencing determines they shouldn't be on yet.)
Motherboard not booting up Issue - ASRock IMB-150 - Page 1
Forum section: electronics / repair

author: Electro Man Bot
author_rank: Newbie
timestamp: February 14, 2024, 09:55:03 pm
content: I have an ASRock motherboard (IMB-150) with Mini-Sata Solid State Drive. I have removed the SSD card and re-inserted. After re-inserting the device will not boot up. During boot up error displayed "Reboot and select proper boot device or insert boot media in selected boot device and press any key".Connections on motherboard and ssd card look in good condition, no signs of wear or damaged connections.During boot up I have pressed F2 to select UEFI setup menu, mSATA 3IE is listed as boot device with no other option available.Anyone have some advice on how to repair/diagnose/fault find..?Thanks in advance for any help..

author: Jwillis
author_rank: Super Contributor
timestamp: February 15, 2024, 01:17:17 am
content: Did you try clearing the CMOS. This will reset the Bios to default. The manual will show which pin header is used for this.

author: paddySparks
author_rank: Newbie
timestamp: February 15, 2024, 08:04:01 am
content: Jwillis is right. Try to clear the cmos. If you cant find the pin as he suggests to reset then take out the coin batt. leave out for a about a minute then put back in and retry.
Motherboard repair - Page 1
Forum section: electronics / repair

author: Fuscus
author_rank: Newbie
timestamp: November 08, 2022, 12:10:04 pm
content: Hello, I've got this Asus Sabertooth motherboard which has got the 1st pci-e slot not working. All 3 others work just fine in their respective x8,x16 modes. I measured 12v and 3.3v, clock, the capacitors on each lane, everything's in check. I resoldered the small part of the slot where the input voltages are but still no success. Any idea what could I check next?

author: bidrohini
author_rank: Regular Contributor
timestamp: November 09, 2022, 11:18:27 am
content: Have you tried all the videos available in youtube? There are different models of your mentioned motherboard I can see.

author: Rasz
author_rank: Super Contributor
timestamp: November 10, 2022, 04:23:38 am
content: how did it stop working? have you tried x1 card in it? First slot is usually directly wired to cpu, might be bad cpu, bad cpu socket etc
Motherboard repair - Page 1
Forum section: electronics / repair

author: gtrak
author_rank: Newbie
timestamp: March 09, 2021, 07:28:46 pm
content: Hello folks, I have a ASUS X399 motherboard. I blew it up by plugging in a PCI-E card backwards when off, shorting some standby voltage. I smelled some smoke, and now the power button does nothing. I think I found what I blew up! I found a hard bubble on top of the top transistor in that pictured cluster.I have a picture from a replacement board, but can't seem to identify the component.Can you fine people help? If it's really as easy as replacing this, it's definitely worth a shot for me to try it.WAG71??

author: james_s
author_rank: Super Contributor
timestamp: March 09, 2021, 07:39:42 pm
content: I found one hit for the WAG marking that sounds promising, PDTA144VT which is a PNP transistor in a SOT-23 package.

author: gtrak
author_rank: Newbie
timestamp: March 09, 2021, 09:59:00 pm
content: I was able to source some PDTA144VT,215, will give it a try, thanks!

author: perieanuo
author_rank: Frequent Contributor
timestamp: March 10, 2021, 02:03:00 pm
content: any pnp 'big' enough will pass the test ... or not
Moto G4 plus charge port continuity?? - Page 1
Forum section: electronics / repair

author: leewald
author_rank: Newbie
timestamp: June 15, 2019, 06:54:31 pm
content: I'm attempting to replace the charge port on a Moto G4 Plus and I think I have continuity issues. The charge port has 5 pins that connect to 5 solder pads on the board. Should any of the 5 pads on the board have continuity to ground? Right now only one pad doesn't show continuity to ground. This doesn't sound normal, right?Thanks
Motobatt Big Boy battery charger/tender - Page 1
Forum section: electronics / repair

author: timg11
author_rank: Contributor
timestamp: June 30, 2025, 10:35:54 pm
content: I have a Motobatt Big Boy battery charger/tender that has failed.I saw thethread here about the Battery Tender, and thought I check to see if anyone had ever repaired the Motobatt?The symptom is no LEDs, no output. The power transformer measures an open primary. There are some burned components on the PC board. Maybe those components failed, then caused the power transformer to open? If anyone has worked on these, do you know if the transformer has a thermal fuse that could be repaired as in this video?As shown, a fuse can sometimes be located and replaced by cutting away some of the tape.Possibly the transformer could be replaced, but it's now difficult to know the output voltage.I'll keep looking, but I thought I'd check here to see if anyone has experience.

author: floobydust
author_rank: Super Contributor
timestamp: July 02, 2025, 11:39:53 pm
content: We want pictures. I haven't seen a battery tender using a mains transformer for many years. It's all SMPS now.
Motor Controller - Broad Ocean KNSAH064001 - PCBEP1000) - Page 1
Forum section: electronics / repair

author: jheatac
author_rank: Regular Contributor
timestamp: June 15, 2024, 06:34:39 pm
content: Disclaimer - I'm very much a novice and don't know a whole lot about what I'm doing.Looking at a motor controller for the inside fan on a hotel style air conditioner. As the title indicates, a Broad Ocean KNSAH064001.It wasn't working - obviously. It blew a couple traces and I'm trying to figure out what is the cause and what is the effect.I have removed the two capacitors C101 and C102. Both check acceptably - They are 220uf @ 250v. Check at 208/209 and 0.21 ESR Both of these have damage to the wrapper from the heat, I would suspect. If they were the cause, and blew the side out of them, I'd expect the readings to indicate they are failed or the the tops to have vented.I removed the 10uf/50v capacitor above IC101. It isn't labeled or was labeled before the fire and gone now. It is shorted. It connects Vdd and Source on IC101 I am suspecting this is the cause.The side is also blown out of IC101. This is a VIPer12A IC. It appears that at least one of the source pins is burnt off at the trace that lead up to failed 10uf/50v capacitor.On the back of the board, SMD diode D103 has its guts hanging out. It appears to be across Vdd and Source.I'm not asking anyone to spend more than a minute or two. This isn't a critical situation, just a learning moment for me. I have a replacement board installed already, I just looked to see if I could repair this one because the new board is ~$130. With the extensive damage, I'm not sure repair is justified other than personal satisfaction.Thanks to all.

author: MathWizard
author_rank: Super Contributor
timestamp: June 17, 2024, 03:28:02 am
content: I'd say it looks repairable, if you can manage the soldering, and get close enough new parts. Is the black thing on the right of the VIPer IC an inductor ? It could read as a short to a lot of DMM's. Overheating MOSFET's, I've seen them get cooked and blow up.It doesn't look like a big circuit, I'd take a DMM, and make a schematic, even in a simulator. Even just the main stuff connected around the IC. A lot of these chips have pretty similar external circuits, and they might even be exactly like what's in a datasheet. There's not many circuits in this datasheet tho.Whats under the heatsink, some motor driver ??
Motor driver circuit fault - Page 1
Forum section: electronics / repair

author: sncnal
author_rank: Newbie
timestamp: June 01, 2022, 06:02:49 am
content: Hi 👋This pcb is control to motor speed(rpm) to laboratory centrifuge device. We have problem, I set speed 4000 rpm but its not going to above 90rpm. Once V15 and V16 mosfets were short but i changed it. It is still the speed isnt going tk above 90 rpm.Thanks

author: fzabkar
author_rank: Super Contributor
timestamp: June 01, 2022, 08:23:28 am
content: Do all the motor phases measure the same resistance?

author: sncnal
author_rank: Newbie
timestamp: June 01, 2022, 09:57:03 am
content: Yes bro, I checked it
Motorcycle low fuel thermistor - Page 1
Forum section: electronics / repair

author: MarginallyStable
author_rank: Regular Contributor
timestamp: April 26, 2023, 09:12:18 pm
content: My low fuel level indicator stopped working, and searching online seems to be a common issue. It uses a thermistor submerged/un-submerged depending on fuel level, and relies on self heating.I have not verified on my bike yet, but it has been claimed that the self heating current is sourced from 12V through a 116ohm series resistance, and a thermistor resistance of <160 ohms is required to set the low fuel alert.The recommend thermistor is 2K@25degC, B=3468K. My calculations say that this will have to get to 100degC to trip the alert.Now the question, is this a reasonable temperature to have inside the (almost empty) gas tank?Anyone have a better thermistor recommendation for this application?

author: floobydust
author_rank: Super Contributor
timestamp: April 27, 2023, 04:44:51 am
content: What package is the thermistor in, i.e. epoxy drop or glass DO-41? How does it get cooled by the gasoline, in a plastic thermowell?There are two issues to confirm, one is the available fault current that the 116ohm resistor limits ~120mA is fine, and two the thermistor open air temperature well below any flash point.The low fuel lamp threshold is important to know.

author: MarginallyStable
author_rank: Regular Contributor
timestamp: April 27, 2023, 04:53:17 pm
content: Did some measurement last night:-Open circuit voltage: 10.5v-Closed circuit current: 78ma-Light trips at about 170ohmsOriginal is mounted in a metal capsule, with holes allowing the gas direct contact to cool.The recommended is a hermetically sealed glass thermistor, plan to attempt to non-destructively replace back into the original capsule.

author: MarginallyStable
author_rank: Regular Contributor
timestamp: April 27, 2023, 04:57:55 pm
content: One other thing to mention, took several R/V measurements. And they are defiantly non-linear, so the assumption that is a simple series resistance is incorrect.

author: floobydust
author_rank: Super Contributor
timestamp: April 27, 2023, 08:19:25 pm
content: 10.5V open-circuit is kind of a dead battery? At 78mA that's around 135 ohm pullup in the module perhaps.At 170 ohms to activate, MF58 DO-41 glass 1kΩ@25°C B=3958 would be at 71°C. I find 1kΩ ref. thermistors are more popular.2kΩ@25°C B=3468 would be at 105°C, seems pretty hot.
Motorola 04s75 obsolete no dataheets what is it? - Page 1
Forum section: electronics / repair

author: 460voltclub
author_rank: Contributor
timestamp: April 29, 2020, 05:50:13 pm
content: I am fixing 1988-1994 Ford EEC-IV PCM (power control modules) for members on another forum for free. The circuit boards are made by Motorola, and populated with Motorola, Intel and Texas Instruments components.I believe that some of these component parts are proprietary and designed just for Ford and were not available commercially.The Motorola 04s75 is a TO-220 package with no pin designations. I don't know its function so what tests can I do to determine what it is?It is getting very hot with 10.4 dcv to the left pin, 5.6 DCV to the center pin, and 10.62 DCV to the right pin. It is supplied or is supplying a 16 pin DIP IC that I can get the data sheet but I have to buy 100 of them to get it.Thank you for any information.

author: fzabkar
author_rank: Super Contributor
timestamp: April 29, 2020, 09:02:23 pm
content: It seems to be a PNP transistor (BCE), probably acting as the pass transistor in a 5.6VDC linear supply.On second thoughts, Vbe is too low for the transistor to be switched on.
MOTOROLA GM900 CUTS TX DURING SPEECH - Page 1
Forum section: electronics / repair

author: Armando1989
author_rank: Contributor
timestamp: November 17, 2021, 09:56:41 pm
content: Hi guysIm not sure if anyone is familiar with these radios however ive bumpt into something ive never seen before. During tx radio intermittently stops tx with my speach on microphone, 😳specially when talking loud near microphone. I see tx led blinking and transmitter on/off as i talk. At first i changed the frequency as i though it might be pll being unlock but seems it does at all frequencies ive tested... Low mid and highest rangeAny 💡?Thanks in advance

author: TheBay
author_rank: Unknown
timestamp: November 17, 2021, 11:07:18 pm
content: Could be a few things, have you checked the voltage on the PSU while this happens?Have you got the Motorola CPS or RSS software and a cable, there may be something strange with the programming or a GPIO setting.

author: Armando1989
author_rank: Contributor
timestamp: November 20, 2021, 02:33:56 pm
content: Hi!Ive indeed tested with 2 different psus working just fine. I have motorola rss and rib to program radio, ive programed different frequs of low and high ends and problem is persistent. Rss has a mainteinance alignement tx but just for reference adjustment and some other adjust related with maximum deviation. I just talk to microphone and as i talk loud red tx blinks and stops transmitting...

author: geggi1
author_rank: Frequent Contributor
timestamp: November 20, 2021, 04:13:45 pm
content: Check the values for transmit timeout.Check also the power output because you might have problems with the PA.http://manuals.repeater-builder.com/mo-files1/-GM%20Series/GM900%20service%20manual%206802100U61-O.pdf

author: Armando1989
author_rank: Contributor
timestamp: November 21, 2021, 08:59:11 am
content: HiI will check timeout and lower tx power however:Are u sure modulation has to do with tx spuuttering?As i know timeout will follow certain time before stops, but no random on/off tx blinking as you shout or talk to microphone.Thanks in advance!Br

author: m3vuv
author_rank: Super Contributor
timestamp: November 21, 2021, 11:43:26 am
content: Hi,i dont know if it helps but i had the same issue with a kenwood ts-50 years ago,only did it on 40m,it was rf getting into the rig due to a faulty antenna trap,as soon as i fixed the trap it worked fine!

author: Armando1989
author_rank: Contributor
timestamp: November 21, 2021, 07:25:30 pm
content: HelloDid some advances... not a matter of the power amplifier, nor pll and frequency deviation thats for sure 100%... Its related with audio processing...I entered service aid menu and check asfic tx settling timmer, increasing it causes tx led stops later and blink slower when talk loud to microphone, reverse happens when decreasing it. Its like audio processing is clipping when talk near mic or loudand causes tx diseable and enable again...So im not sure about this feature is doing but for sure is related with this symptom, i wonder if this iss normal and happens in other gm900, but its weird thing for meBR
Motorola TYA324 IC - Page 1
Forum section: electronics / repair

author: chronos42
author_rank: Regular Contributor
timestamp: November 29, 2020, 10:42:45 am
content: Hi together,I found an NOS operation amplifier chip in my stock, that is kind of mystrious for me.The chip was manufactured 1980 an has the old Motorola logo on it. It is clearly recognized as a LM324 or LM2904 from a chip tester.But why is it labeled asTYA324 instead of LM 324? What is TYA meaning? I cannot find any information about a TYA 324. Is there something special with this chip or why this strange labeling?Does anyone have any information about it?

author: fzabkar
author_rank: Super Contributor
timestamp: November 30, 2020, 08:25:37 am
content: I couldn't find anything on the TYA324P, but I did find lots of TYA chips made by Motorola. Most of them appear to have equivalents with regular part numbers.FWIW, here is a Motorola document dated 2004 which mentions the TYA7805CTV and TYA7809CTV 3-terminal regulators:https://www.onsemi.com/pub/docs/pcn/13701.pdfThe above regulators were used in Sony CRT TVs:https://www.google.com/search?q=filetype%3Apdf+filetype%3Apdf%20TYA7805CTV

author: chronos42
author_rank: Regular Contributor
timestamp: November 30, 2020, 10:14:54 pm
content: Thank you for your answer.Maybe these parts are made for consumer products, cheaper but with less quality screening?I don't know. But the fact, that this chip simply does not not exist in the Motorola databooks let me believe that this was a kind of custom manufactoring, cheaper, but mayby slightly out of the standard specifications for a LM324, so it could not be sold as a LM324. But good enough for consumer stuff.The most annoying thing is, that I have no idea how this part came in my stock....