hybridfree/eevblog-posts huggingface dataset:
Help Identify A Component - Page 1
Forum section: electronics / repair

author: The Doktor
author_rank: Regular Contributor
timestamp: December 23, 2023, 02:00:24 am
content: The component I'm trying to identify is a 6-pin dip IC from a microwave oven control board. The board has a Motorola logo, and is marked 1979, 1475E01, 80C-F, and a few other minor markings.Chip is 6 pin, with pins 1,2,4, and 6 connected. All 6 pins are present. It is marked as follows:[Motorola logo]01S638026I've had no luck with google. Knowing what it is would be helpful, as there are a few resistors which have obviously been severely overheated connected to it. I thought bridge rectifier, but I usually see those connected on 1,3,4,and 6 with the unused pin positions unoccupied.ThanksEd

author: wraper
author_rank: Unknown
timestamp: December 23, 2023, 02:04:04 am
content: Can you post a photo? 6 pin sounds like optocoupler.

author: wraper
author_rank: Unknown
timestamp: December 23, 2023, 02:08:00 am
content: I found 01S63 in this document mentioned among other optocouplers

author: The Doktor
author_rank: Regular Contributor
timestamp: December 23, 2023, 02:17:15 am
content: Optocoupler was my second guess.

author: wraper
author_rank: Unknown
timestamp: December 23, 2023, 02:17:19 am
content: Seems to be optotriac, here is what I found about 01S63A. Should be similar to very common MOC3021.Quote
Help identifying 3.5mm connector part number - Page 1
Forum section: electronics / repair

author: Sparker
author_rank: Regular Contributor
timestamp: October 05, 2019, 02:34:05 pm
content: Hello!I need some help with identifying the part number of the 3.5mm audio connector on this printed circuit board.I've looked through Digikey and Mouser and couldn't find a direct match for it.It's a PCB from the front panel of a Fractal Design Define PC case. Only after a year of use the audio output connector has stopped working properly.Any help would be appreciated!
Hello, can you help me to fix my UT139E multimeter please - Page 1
Forum section: electronics / repair

author: Wael_SY
author_rank: Newbie
timestamp: September 08, 2020, 08:20:26 am
content: Hello, can you help me to fix my UT139E multimeter please.This video explain the problem :https://drive.google.com/file/d/1fwmag8HaSDEyc82Ig0HRGywlxoDaO-bd/viewThank you.

author: daedalux
author_rank: Contributor
timestamp: November 11, 2020, 10:09:40 am
content: The only thing i have discovered about this meter after failure is that when turning it on while pushing the round buttons you enter calibration mode.

author: Asterix
author_rank: Contributor
timestamp: November 12, 2020, 01:45:51 am
content: Hi!I think it needs calibration. I am not en expert on that.I do wonder if maybe it was dropped? Or the battery might have leaked?Or some liquid damage?If the problem was caused suddenly i would suggest to check that.
Hello everybody and HELP! Vacuum cleaner reassembly. - Page 1
Forum section: electronics / repair

author: Verge
author_rank: Contributor
timestamp: November 02, 2024, 06:40:45 pm
content: I am sure that "a" goes to "5" and "b" goes to "6".... the rest I'm not sure so...Aptitude test: IF WE FAIL, THE SUCKER BURNS!So help us God...a5,b6,

author: coppercone2
author_rank: Super Contributor
timestamp: November 02, 2024, 06:48:49 pm
content: man just use a broom its not worth it

author: Verge
author_rank: Contributor
timestamp: November 02, 2024, 06:53:45 pm
content: ....bzzzzzzzzz .... / shhh...shhh...shhh...shhh...shhh...... I'm getting a new one but I thought it would be a nice project to resurrect it... for cig ashes in the smoking area.plus: I cannot solder a broom

author: Gyro
author_rank: Super Contributor
timestamp: November 02, 2024, 09:07:32 pm
content: What the hell happened?That black wire looks as if it's been through a hedge backwards rather than tinned and soldered.

author: Verge
author_rank: Contributor
timestamp: November 02, 2024, 09:51:28 pm
content: yeah! ... I've drained the battery by attaching it directly to the motor...) savage... I know...It was prepared for recycling but I had a change of heart.If it's too difficult I'll probably make something else with the motor but all components are still functional.

author: coppercone2
author_rank: Super Contributor
timestamp: November 02, 2024, 11:57:02 pm
content: draw a schematicyou did the first step now its time for paper

author: eurgenca
author_rank: Regular Contributor
timestamp: November 03, 2024, 07:33:14 am
content: Hi, could be.M- and M+ motor - and +B- and B+ battery - and +C- and c+ charger - and +

author: Verge
author_rank: Contributor
timestamp: November 03, 2024, 10:55:46 am
content: coppercone2ooooh... I see what you're doing!!!true If I wouldn't been too old [in psy-sociology I'm like you are now in electronics (... probably; )]In electronics I am at the level of battery+switch+bulb ... I look at the tiny monsters on the PCB...I'm from Eastern Europe though and that means that I've burnt my fair share of circuitseurgencaThanks! I'll put them like that and try to figure the circuit out, I'll let ya'll know.P.S. I'ts cool the feeling of figuring things out ... true?

author: Verge
author_rank: Contributor
timestamp: November 03, 2024, 09:58:10 pm
content: Massive success!!! WE'VE DONE IT! ... It's aliiiive! Many thanks to eurgenca for my first electronics course.... it was written on the board HAHA! what a noob I am,I sure have an electronist's heart because I loooove soldering ... the solder getting into the wire... what a satisfaction!Thanks and have a nice life,see you at the next project.V.

author: Analog Kid
author_rank: Super Contributor
timestamp: November 03, 2024, 11:28:40 pm
content: Quote from: Verge on November 03, 2024, 09:58:10 pmYes, that is satisfying, isn't it? When the solder just all of a sudden soaks into the hot connection, all smooth and shiny ... mmmmm.
Hello, help me identify burnt power supply elements Techsolo TP-730 - Page 1
Forum section: electronics / repair

author: trek1203
author_rank: Newbie
timestamp: July 08, 2024, 07:08:56 am
content: PFC - CM6805BG

author: m k
author_rank: Super Contributor
timestamp: July 14, 2024, 05:44:11 pm
content: Pretty hopeless without a schematics.J2 can be zero ohms jumper, R18 same as R19.Bottom pair of transistors can be the same, but upper pair is something else.R45 could be 581.Quite a zap.It can have taken with it some others also that have no external marks.

author: asis
author_rank: Frequent Contributor
timestamp: July 14, 2024, 07:45:16 pm
content: Hi,Look at the standard diagram - it will be easier to navigate (page 14).https://semiconductors.es/datasheet-pdf/938655/CM6805.html

author: DavidAlfa
author_rank: Super Contributor
timestamp: July 14, 2024, 08:05:10 pm
content: Probably the primary switching transistors shorted and the HV (300V+) went everywhere, pretty sure there're lots of other roasted stuff.
HELP!!! BMS? Lithium battery pack common fault mobility scooter - Page 1
Forum section: electronics / repair

author: tomcolesy
author_rank: Newbie
timestamp: March 13, 2023, 06:37:10 pm
content: Hey guys. First post for me.I currently have quite a few battery packs that are fitted into mobility scooters. The pack is self is in a box with 2 fittings. It is also fitted with a BMS. One for the load of the scooter and the other for the charger. I am getting a reading on the charger port but the load is showing nothing. Both ports if connected to a charger is allowing the pack to charge. It seems that this is a common fault on these batteries as I have had this on numerous occasion. What I have found strange in the past is I have removed the BMS and charged the pack. After refitting the BMS it has worked. Other times it hasn't. I am unsure if it is the BMS at fault or it is just me being stupid. I'm really stuck at the moment and any input would be greatly appreciated.Thanks in advanceTom

author: Swake
author_rank: Frequent Contributor
timestamp: March 13, 2023, 09:59:08 pm
content: Have you switched it off and back on?Our crystal balls aren't working anymore. How do you think we can help with the massive amount of information you provide?What scooter? What battery? What charger? What BMS? configuration? Schematic? Pics?

author: abdulbadii
author_rank: Frequent Contributor
timestamp: March 14, 2023, 03:06:28 am
content: have ensured all are cleans, every conductive connections is 100% unrusted ?good if image inserted here

author: SMdude
author_rank: Frequent Contributor
timestamp: March 14, 2023, 03:28:07 am
content: Check that all cells in the pack are reading the same voltage. If you have a cell gang that is down/up in voltage, the BMS will not allow it to run.Typically if a cell gang is out of balance with the rest, there will be a weak cell amongst them.When making/rebuilding packs, you need to make sure the ESR of the cell gangs match. And for this reason, you cannot just replace a bad cell.
HELP! dbTechnologies B-Hype 15 Speaker burned IC - Page 1
Forum section: electronics / repair

author: Aller
author_rank: Contributor
timestamp: November 17, 2022, 01:33:27 am
content: Hi Everyone!Does anybody have a schematic for the Power Supply board for dbTechnologies B-Hype 15 Speaker? The IC "U1" is blown beyond recognition (see picture), so maybe just the chip code? Board E356428 SY-JLH -02. PLEASE!

author: DavidAlfa
author_rank: Super Contributor
timestamp: November 17, 2022, 02:39:21 am
content: Try finding the FCC ID on the product sticker, sometimes they have nice internal pictures.Hard to tell, a larger picture of the board might give more hints.

author: Audiorepair
author_rank: Frequent Contributor
timestamp: November 17, 2022, 09:51:47 am
content: dB used third party Digipro boards in some of their speakers, as do RCF.If it's a Digipro board it will probably be marked as such, so maybe widen your search to Digipro and/or RCF, you might get lucky.This one attached I know is used in both RCF and dB.(The entire service manual is too big to post here)Try here:https://elektrotanya.com/showresult?what=db-technologies&kategoria=All&kat2=All

author: Audiorepair
author_rank: Frequent Contributor
timestamp: November 17, 2022, 11:50:51 am
content: Ah, should have checked before posting, your speaker is a low powered low priced unit, so will probably have a small unknown SMPS.I have had similar chips come in blown up, and have been able to find the piece that blew off with its markings completely intact!One caveat, though, an increasing number of these SMPS controller IC's are now unavailable anywhere in the world from any reputable supplier.So the only option is a questionable one from China.When that doesn't fix the problem, you will be in an unenviable position of not knowing whether its just a fake chip that doesn't work, or there is some other problem, or both.

author: Vicus
author_rank: Regular Contributor
timestamp: November 23, 2022, 09:23:32 pm
content: Never repair a b-hype. Can you post a wider view o the damaged area?

author: fzabkar
author_rank: Super Contributor
timestamp: November 23, 2022, 09:49:36 pm
content: I notice that the Digipro circuit has an APFC section. If the damaged IC is an APFC controller, then it may be possible to bypass this section.

author: Vicus
author_rank: Regular Contributor
timestamp: November 24, 2022, 01:38:02 pm
content: B-hype speaker don't use digipro module.

author: djvitaha
author_rank: Newbie
timestamp: October 01, 2024, 05:44:45 am
content: A lot of time has passed since the post, but still: U1 - IR2156SFrom the power supply board-gain db technologies b-hype 12 I think it's the same thing.Maybe someone already has a scheme? There is a need.
Help! How to modify the maximum output current of Huayi 7142 voltage tester? - Page 1
Forum section: electronics / repair

author: luyu
author_rank: Newbie
timestamp: April 02, 2025, 05:51:29 am
content: Recently purchased a Huayi 7142 voltage tester, AC maximum output current indicator is 20mA, but the actual can only set 3mA, help friends how to modify this? Thank you!

author: Swake
author_rank: Frequent Contributor
timestamp: April 02, 2025, 07:44:56 am
content: This thing is sold under multiple brands. Extech is one of them.Manual attached.Some instructions about setting current at the end of page 18 and continues on page 19.Might also be related to calibration. They call it 'correction' in the manual. Bottom of page 51 speaks about AC current.There seem to be 2 measurement ranges for current. The first range is 3.5mA. Could not find out if this is autorange or need manual selection.

author: luyu
author_rank: Newbie
timestamp: April 02, 2025, 08:33:51 am
content: Thank you!Here are some additions to the machine model。

author: luyu
author_rank: Newbie
timestamp: April 02, 2025, 08:46:56 am
content: Thank you for your answer！After reviewing the documentation you provided, the problem still hasn't been resolved.

author: Swake
author_rank: Frequent Contributor
timestamp: April 02, 2025, 10:59:06 am
content: Does it allow to change the setting to something lower, like 2mA?Would you have a brand/model that does not support 20mA?Have you inspected the internals to verify if there are jumpers for selection or something similar?There does not seem to be much information available about this device. Please document as much as you can. Take detailed pictures of everything and certainly the PCBs front and back. Try identifying as much components as possible to allow for a later repair.

author: coromonadalix
author_rank: Super Contributor
timestamp: April 02, 2025, 11:08:16 am
content: i would have said re read the manual and understand the settings and operation(s) if it really does the 20ma settings or as written, it as ranges to set ?some seems to be modifiable, some could be locked down ... or need to be unlockedi had one of these from Gw Instek, man this one was complicated to set, a before, an under test, and after test settings, rotate knob to set .... each time it was sent to cal labs, it was a 15-20 minutes re putting all the configs ..or find the "clones" manuals and try to figure out the settings too

author: luyu
author_rank: Newbie
timestamp: April 02, 2025, 12:31:31 pm
content: hiSet the current equals or less than 3manoneOnly a pair of jumpers were found for whether the screen is enabled or notMachine photo supplement：

author: luyu
author_rank: Newbie
timestamp: April 02, 2025, 12:35:22 pm
content: hiThe relevant manuals have been read and tried, but no solution has been found
[Solved] Kikusui KSG4100 Sig Gen Circuit diagram needed - Page 1
Forum section: electronics / repair

author: SuomiKiwi
author_rank: Newbie
timestamp: May 14, 2024, 04:38:13 pm
content: This is a shot in the dark as I have been unable to turn up any schematics of this 25 year old sig gen. I purchased this off eBay and it works..mostly. I have the operations manual which is great but not so good for fault finding. The unit cannot change frequency, modulation, amplitude using the rotary dial. It all works fine with manual data entry so its just a minor annoyance..but still. Its really useful to tune the output manually. In any case I dissasembled the front panel, hoping for an easy fix but its not to be. I can still chase the logic states around the front panel with a scope but a schematic would be really useful, can anyone help? Kikusui themselves couldn't help me as they told the product was discontinued 25 years ago and is not supported...no surprise but no offer of a manual from the archives came either.

author: coromonadalix
author_rank: Super Contributor
timestamp: May 14, 2024, 04:52:45 pm
content: ask directly at KikusuiUnder an non disclosure agreement they could accept to send you schematicsThey did for a few EEVblog members here for psu's ... me included

author: SuomiKiwi
author_rank: Newbie
timestamp: May 14, 2024, 05:40:36 pm
content: Thanks, I did try that but got the following response;KSG4100 of Signal Generators is very old model and the model was discontinued since over 25 years ago.Unfortunately, we finished repair support and providing technical documents for this model.Sorry for the inconvenience but thank you for understanding.So looks like hand drawn schematic time for me....

author: SuomiKiwi
author_rank: Newbie
timestamp: May 15, 2024, 04:57:07 pm
content: Handchasing the logic lead me to the CPU which is housed in one of the internally screened modules. A hard reset using the unlabelled switch on the CPU fixed the problem. Kikusui thoughtfully provide an access hole to the resetswitch so actually no need to even remove the screened cover. The service manual would have saved me a ton of time but we got there in the end.
Help! Stuck for IC data - Page 1
Forum section: electronics / repair

author: najrao
author_rank: Regular Contributor
timestamp: December 03, 2020, 12:40:54 pm
content: To save a life, would anyone in the know decode this IC for me?I cant even identify the logo. The legend says LS4001S.Thanks a million.

author: aqibi2000
author_rank: Regular Contributor
timestamp: December 03, 2020, 01:35:58 pm
content: LS —> ON Semi Conductor is the manufacturerIf you search IP4001S you’ll see it’s a 5 channel motor driver ICData sheet uploadedhttps://datasheet4u.com/mobile/509005/IP4001S.htmlI take bitcoin and PayPal

author: najrao
author_rank: Regular Contributor
timestamp: December 03, 2020, 02:01:09 pm
content: How is that for service! Thanks aqibi2000.How is one to know LS is used by ON ?

author: aqibi2000
author_rank: Regular Contributor
timestamp: December 03, 2020, 04:56:19 pm
content: https://www.google.co.uk/amp/s/www.ultralibrarian.com/resources/blog/2020/09/15/list-of-ic-manufacturer-codes-ulc/amp/

author: fzabkar
author_rank: Super Contributor
timestamp: December 03, 2020, 06:46:11 pm
content: According to this site ...https://monitor.net.ru/forum/threads/87762/page-2LS4001S=IP4001IP4001=KA9259Dhttp://www.ic72.com/pdf_file/k/54143.pdf(KA9259D)
Help !!!! Query on PNP voltage regulator on a HK subwoofer - Page 1
Forum section: electronics / repair

author: rfengg
author_rank: Regular Contributor
timestamp: December 28, 2022, 05:15:52 pm
content: Hi there,Was trouble shooting a HK subwoofer and found a broken MMBT 4403 BJT which caused the subwoofer to not produce any sound......changed the transistor (B-E junction was open) and she sings again.I had access to the subwoofer service manual but cannot get my head around the implementation the simple circuit which I have attached.-7VSB is fed to the collector of the MMBT 4403 PNP transistor and between the base and collector there is a 1K resistor. There is a 7.5V Zener to ground and as the voltage is only -7V, the zener is cutoff.In this scenario , how does -7VSB appear at the emitter? What exactly is the purpose of this implementation?thanks

author: Chris56000
author_rank: Frequent Contributor
timestamp: December 28, 2022, 06:25:57 pm
content: That circuit is a negative mirror–image of the common NPN emitter follower regulator used with positive supplies!Even if the supply voltage is too low to enable the zener diode to conduct, it will still produce an output, because the base voltage of the transistor will only be about 0.1 to 0.2 V above the collector, relative to positive earth, and the emitter/base junction of the transistor will be forward biassed, because the cathode of the emitter/base diode goes to a point more NEGATIVE than its emitter, so you will get the forward emitter voltage drop of a PNP transistor, giving an emitter voltage of about –6.4 V.Think of it as you would with the usual NPN emitter follower stabiliser, but with positive voltages replaced by negative ones!Chris Williams

author: wasedadoc
author_rank: Super Contributor
timestamp: December 28, 2022, 06:28:58 pm
content: Quote from: rfengg on December 28, 2022, 05:15:52 pmZener diode followed by emitter follower. What don't you understand?The input on the left side is labelled -7 Volts. That does not necessarily mean it is -7 Volts. It means that it is the raw input which will be used to provide the -7 Volts on the output side.

author: Audiorepair
author_rank: Frequent Contributor
timestamp: December 28, 2022, 06:34:24 pm
content: Either the -7vSB on the left side is a typo or is misleading at best.

author: rfengg
author_rank: Regular Contributor
timestamp: December 29, 2022, 02:16:11 pm
content: Thanks Chris......I tried this on the breadboard using a PNP BJT after ensuring that the -7VSB was indeed only -7V by measurements taken on the subwoofer.So the zener is indeed cutoff completely but I failed to recognise that the emitter is pulled to a higher voltage thru the load connected to ground which indeed forward biases the BE junction.Thanks for your inputs
Help 18s BMS with 18 wires connection - Page 1
Forum section: electronics / repair

author: marce002
author_rank: Regular Contributor
timestamp: May 16, 2025, 01:52:20 pm
content: Hello this is Ecooter brand motorcycle and need to test bms working ok and if posible locate uart or tx rx capabilities but first i want to connect it!!!it only have 18 wires to be used in 18s !! so how do i connect?if i connect as usual the last cell will not be monitored right? missing last wire?if 18s and 18 wires what to connect first? the battery - pack ? or the 1st positive cell?

author: tunk
author_rank: Super Contributor
timestamp: May 16, 2025, 02:49:43 pm
content: An uneducated guess - common ground? I.e. the18 wires goes to the positive ends of the cells?I guess you could test and see if the rightmostresistor is connected to ground (through a transistor).

author: marce002
author_rank: Regular Contributor
timestamp: May 17, 2025, 11:52:21 am
content: yes i have connected the " -" gnd bat pack (72.4v) to a black thick wire labelled " -pack " and the 1st positive to b0 the next + to b1 and so on . last wire is for 18th cell + ...okbut the volt output is not 72v but 68.4 and tjis is wrong!!

author: tunk
author_rank: Super Contributor
timestamp: May 17, 2025, 12:04:52 pm
content: A fully charged li-ion cell is 4.2V, fully discharged 3.0V.68.4V is 3.8V/cell which is a bit more than half charged.

author: marce002
author_rank: Regular Contributor
timestamp: May 17, 2025, 01:18:14 pm
content: i know that... what im saying here is the fact that the output volt is different from the packpack itself is 72vbms charger/power output is 67vthey should be the same..mosfets are ok... cells are 4.0 +- .2v

author: marce002
author_rank: Regular Contributor
timestamp: May 18, 2025, 01:16:05 pm
content: To be clear the output Vol pack alone is 72v as expected ok? but connected to BMS from -PACK to b18 last positive is 67.7v!!! why??A green led remains on onboard i do not what it means maybe a balance on progress of my 18s 1p 18650 test pack below... it does not seem to charge either.

author: ME
author_rank: Frequent Contributor
timestamp: May 19, 2025, 05:09:09 am
content: What is the battery chemistry lifepo4 or colbalt?

author: inse
author_rank: Super Contributor
timestamp: May 19, 2025, 04:20:02 pm
content: Why do I only count 17 balancing resistors?

author: tunk
author_rank: Super Contributor
timestamp: May 19, 2025, 04:26:15 pm
content: Quote from: inse on May 19, 2025, 04:20:02 pmSo I thought at first, but number 18 is a bit upwards to the left.

author: marce002
author_rank: Regular Contributor
timestamp: May 19, 2025, 05:29:02 pm
content: chem is liion 18650...yes 18 resistors one is misplaced... maybe 17s.?? why so hard to understand how to make it work... i cant find any info , maybe a bit old board but anyway i should make it work... i have reveived dismantled. green led still on it is doing some kind of balancing maybe because cells are no more 4.0 but around 3.8 now... main problem still is CANT ACCEPT 75V CHARGE AND CANT see 72v at output (3 black wires joined i guess -P -C and another one) is 68.3v but the pack is 72v
Help about fousrite 2i4 - Page 1
Forum section: electronics / repair

author: cyj
author_rank: Newbie
timestamp: July 09, 2021, 05:45:54 am
content: Hello, I tried to repair my 2I4. But I lost C39.C38.C40.C41.C42.C43.C81.C113.L12,L13.L10,L9,L4. Do you have any relevant parameters? Forgive my English is not very good. Thank you
Help about Repairing my laptop - Page 1
Forum section: electronics / repair

author: EbarlaS
author_rank: Newbie
timestamp: May 17, 2022, 03:40:52 am
content: Hi everyone. I am trying to identify the problem of my old laptop. I upload part of aschematic of the laptop which i am thinking that is causing the error.The schematic is showing power plane reg 3/5v.In the schematic, circuit has 19.5v at IN pin when i check the c169 cap. And mosfet U15, U12 has power like 19.5v also but there is no voltage at gates. L15 and L13 have no voltage which must be 5v and 3.3v always.So my question is the circuit shorted and dead that why no voltages or anything else could be possible.And if this curcuit is the problem i will try to replace. Can u tell me codes meaning on them.Maxim 17020 ETJ 950 + ITOZI found onlineMAxim 17020 ETJ 848 + NTATSo is it okay to replace with this one?It will be great if i can get help thanks everryone who can advice me..

author: unknownsoldier90
author_rank: Contributor
timestamp: May 17, 2022, 11:47:42 am
content: What Laptop are you trying to repair?What about the first 2 input MOSFETs, are they fine?I would also recommend the badcaps Forum, there are many specialists.

author: EbarlaS
author_rank: Newbie
timestamp: May 17, 2022, 01:45:54 pm
content: Hi.. my laptop dell 1750First 2 mosfet are fine 19.5v present after that no power in the 3.3v 5v power supplies..Thanks for the advice i can try the other forum.

author: unknownsoldier90
author_rank: Contributor
timestamp: May 17, 2022, 02:43:59 pm
content: Test the mosfets in diode mode without power.It isn’t guaranteed that they are okay, they can be shorted.Also measure the resistance to ground on the big coils. Possibly a faulty capacitor. If you find a rail which has low resistance try to insert voltage (1v, 1a) and see what is becoming warm.

author: fzabkar
author_rank: Super Contributor
timestamp: May 17, 2022, 09:22:04 pm
content: Are the two supplies being switched on? Check the ON1/ON2 pins (pin #14 = 5V enable, pin #27 = 3V enable).

author: EbarlaS
author_rank: Newbie
timestamp: May 18, 2022, 06:55:06 am
content: I think the problem is more complicated than i can fix. I was thinking since no 5v 3.3v present the problem could be that driver or around but when i check the graphic card the caps around are shorted. Almost all connected +1.05v power lane, they are shorted. Both sides of the caps connected to ground which is not possible, i removed some and checked they were okay. From this driver 5v leading to U49 Circuit which is +1.05v which is connected to grapic card and cpu i guess.All shorted so dont know if it is the card or somethin else.I am putting the diagram of U49 chipset and graphic card.I am not so sure if this is right or not but i remove u49 and mosfet but sshort was still there..Thanks for the advices

author: fzabkar
author_rank: Super Contributor
timestamp: May 18, 2022, 05:34:41 pm
content: A GPU core typically has a very low static resistance of less than 1 ohm.
Help / advise on HP 8714ET network analyser repair  - Page 1
Forum section: electronics / repair

author: matthieu.e
author_rank: Regular Contributor
timestamp: November 14, 2023, 11:08:53 pm
content: Hello,I have an opportunity to buy a HP8714ET network analyser with 1 error on self test :Main DRAM tests failed.I attached the screenshoot. I need one but don't know if I should buy this one.Is it something fixable or should I avoid this unit ? Do you think I can still use it with this problem ?Thank you

author: Stray Electron
author_rank: Super Contributor
timestamp: November 14, 2023, 11:27:06 pm
content: I'm not familiar with the 8714 so I can't advise you but did you look to see if there is a service manual for it? IMO, the availability of those is one of thegoodthings about HP equipment. Also since it's DRAM, I wonder if there is a memory backup battery in the unit that has died?

author: matthieu.e
author_rank: Regular Contributor
timestamp: November 15, 2023, 10:02:24 am
content: Hello, yes I am checking the service manual right now.I think I will buy this unit and see 1 if it is usable with the problem and 2 if it is fixable.I will post more picture when I got itHere is the service manual :https://keysight-docs.s3-us-west-2.amazonaws.com/keysight-pdfs/8712ES/8712ET+ES+and+8714ET+ES+RF+Network+Analyzers+Se.pdf

author: matthieu.e
author_rank: Regular Contributor
timestamp: November 15, 2023, 10:08:49 am
content: From what I see in the service manual I will need to check the CPU board.I will need to check this part :"DRAM control circuitry U412-U414, DL401DRAM data interface chips U406-U409, U421-U424 DRAM address MUX U427-U432DRAM SIMM (J401)"

author: jwet
author_rank: Frequent Contributor
timestamp: November 16, 2023, 03:15:21 am
content: Older equipment has actual component level, service manuals with full schematics, etc. What you posted is kind of module level but this is what they did around 2000, even HP stopped publishing all that detail and adopted a Depot Level Module Repair Model. I would generally rather have a bit older box with good docs than the later model. I have an HP4195 Network and Spectrum Analyzer that is old school and fully documented and an HP4396B that is an equivalent newer model that has the module only repair. Its never broken but it will be a tough repair when it does. For old equipment that is popular, modules are sometimes available, especially for higher failure rate times. An ebay search will usually give you a hint.Having said all that, a DRAM failure doesn't sound like a real tough thing to run down RAW DOG without component level docs. Hopefully, the built in test didn't just stop on the first fault and after you get your DRAM fixed, you'll have more.Good Luck.

author: Tubes
author_rank: Newbie
timestamp: November 28, 2023, 09:35:10 am
content: I think the DRAM module is failed. That is 32MB SIMM 72pins module. You can get it from an old computer or ebay.
Help Agilent E4406A Pulling down the power supply not starting - Page 1
Forum section: electronics / repair

author: jessejgm
author_rank: Newbie
timestamp: April 11, 2024, 08:18:41 pm
content: I have one E4406A with the same problem. I didn't disassemble it. I saw comments that could be the power source. Do I check the power source directly?It has the same characteristic sound. And it does the same as the video in these links. Strange that before it was working perfectly.https://groups.io/g/HP-Agilent-Keysight-equipment/message/137005https://groups.io/g/HP-Agilent-Keysight-equipment/message/131835I will tell you the tests I did.I turned off all the accessories.I did a good cleaning.I only left the motherboard with the fan controller.I replaced all the 100k 1206 and 150k 1206 resistors. Same problem. I measured the old resistors and checked that they were good, and put them back in.The source LED turns on (green), but I hear a noise when it pulses.The red LEDs on the fan control board sometimes light up (red) and sometimes not.Same problem continues.HiI'm doing as it says in the manual.I don't have the tensions. And every time there is a pulse it resets the voltages. Both + and -.The processor LEDs always blink.

author: m k
author_rank: Super Contributor
timestamp: April 21, 2024, 02:37:15 pm
content: Short whining sound with pulsing power LED is many times an overloaded power supply.
Help calibrate-adjust a Fluke 185 - Page 1
Forum section: electronics / repair

author: giosif
author_rank: Frequent Contributor
timestamp: July 07, 2019, 07:59:26 pm
content: Hello,I have a Fluke 185 meter IbelieveI repaired but which is still displaying the "Uncal" message.And readings are also off, so it definitely needs recalibration.Anyone on the forum (UK based) who has the right gear and would be willing to help recalibrate this meter, please?I'd normally try to do this on my own, but I don't have the right equipment (i.e. calibrator) and, even more, this type of meter also requires Fluke's Met/Cal software to perform the calibration.I've asked Fluke (as well as Tektronix) if they could at least tell me the commands sent via the IR port to initiate and perform the calibration, but they ultimately couldn't/wouldn't provide the info.Thanks!

author: giosif
author_rank: Frequent Contributor
timestamp: July 11, 2019, 06:55:45 pm
content: Bump, please
Help, converting PLaystation 1 power supply to 220v - Page 1
Forum section: electronics / repair

author: OverclockVintage
author_rank: Contributor
timestamp: November 26, 2021, 07:10:18 pm
content: My Playstation one is of the model SCPH 90001, the bulk capacitor that it came with is a 47uf 350v, while most 120v Playstation ones comes with a 120uf 200v, so i wonder what capacitor should i use to convert it from 120v to 220v, should it be a 47uf 450v? Also i do have some 87uf 400v, wil it work? I know that the varistor, iscap and fusible are all rated at voltages of 250v or more, so i should just replace the bulk capacitor right? Thanks.

author: fourtytwo42
author_rank: Super Contributor
timestamp: November 26, 2021, 07:25:00 pm
content: Why not use an auto transformer like everybody else who has this problem because your list of parts so far is way to small (meaning its much more complex than you think).

author: fzabkar
author_rank: Super Contributor
timestamp: November 26, 2021, 07:25:56 pm
content: I wouldn't do this. In my experience the only time such a conversion is feasible is when the design allows for it. Typically these dual voltage designs have two bulk capacitors in series. When 120VAC is selected, a link is connected between AC neutral and the junction of the capacitors. This acts as a voltage doubler. For 240VAC operation, this link is removed.I could be wrong, and it could be that the design has enough leeway to do what you are proposing, but I doubt it.

author: ambrosia heart
author_rank: Regular Contributor
timestamp: November 27, 2021, 12:00:39 am
content: what capacitor should i use to convert it from 120v to 220v, should it be a 47uf 450v? Also i do have some 87uf 400v, wil it work?Never do this. Several important points need to be considered.0.Starting resistors rating1.EMI filter rating2.Large cap rating3.Mosfet rating4.photo-Coupler choice5.Most Important: design of switching transformer~~~magnetic saturation.If you want to ruin your stuff at fast rate, just do it.
Help diagnose LCD picture problem - Vestel 17MB82-2 - Page 1
Forum section: electronics / repair

author: shakalnokturn
author_rank: Super Contributor
timestamp: October 12, 2021, 11:24:11 am
content: TV repaired a few weeks ago for a dead backlight LED. After some hours of use the backlight is still good it now has lost the picture.Model:Brandt B3220HDLED (Vestel 17MB82-2 based. Mediatek MT5820LUNU)Panel:VEL_LCM VES315WNDS01_IPS11_32185_MB95T-Con:LSC320AP01-L03 (SM4108 based.)I'm looking for a little guidance to decide where the trouble is coming from.The symptoms came suddenly one day at power-up from standby, before there were no picture defects.I'm suspecting the panel electronics which are unfortunately bonded to the panel itself, single COF is bonded to glass obviously but also to T-Con board.Things I've done so far:Disconnected and reconnected LVDS at both ends.Applied light pressure and torsion while powered to LVDS connectors and T-Con.Scoped the LVDS lines, there is activity and changes in stream if I bring up the TV's menu.I didn't see anything move on LVDS cable's "SCL_I" and "SDA_I" lines these lead to IC1 (SM4108) through a few resistors.Are these lines actually used for communication between MT5820 and SM4108?Measured DC values of test points that had names looking power related on T-Con. (Yes, the fuse is OK...)VIN: +11.8V (Input from LVDS cable)VDD1: +3.26VVDD1L: +3.26VF_VCOMR: +6.68VVCOM: +6.68VF_VCOM: +6.7VVCST: +6.1VHAVDD: +8VVONE: +28.3VAVDD: +16VVCC: +3.27VVOFFE: -9VVSS: -7.44VI know I'm going to spend more time on this than the TV's worth but the learning experience is quite valuable to me.

author: shakalnokturn
author_rank: Super Contributor
timestamp: October 14, 2021, 12:09:00 am
content: I've made more measurements but still don't know what to make of all this...DC values at test points:CV0: +6.63VVREFL_L: +0.228VVREFL_H: +7.057VVREFU_L: +8.26VVREFU_H: +15.097VConfirmed that LVDS interface looks good except for non differential lines SCL_I, SDA_I that never change state. Should they?Also scoped some test points close to the T-Con to COF bonding, I didn't see much happen on points CK1_1, CK1_2, CK2_1, CK2_2.Either there's no movement there or the frequency is much too high to show on my scope (500MHz probes and FE bandwidth), problem is I don't know what to expect there in normal conditions...Anyone have any clues or suggestions on what to measure next?A datasheet or any schematic containing the SM4108 could be helpful also.

author: shakalnokturn
author_rank: Super Contributor
timestamp: October 14, 2021, 12:13:13 am
content: More test points...
Help Diagnose Samsung Odyssey+ VR HMD - Page 1
Forum section: electronics / repair

author: joystik
author_rank: Contributor
timestamp: March 09, 2020, 03:12:13 am
content: Hi guys. Looking for your help again.Tl;Dr: I screwed up and sent 12v on the usb power to the oddysey HMD. Now only recognized as usb 2.1 device instead of 3.0 or 3.1 like before.I got this VR HMD from samsung on sale from amazon. However, I had problems and wasnt getting recognized as a monitor, only the usb 3.0+ device, so I searched everywhere and the most likely cause was insufficient power from USB ports. Bought a PCIe USB 3.0 dual port card with molex power connector for it, but the power connector came off when I applied a little force. So, I went ahead and soldered back on...but, backwards().To be honest, I felt really proud with the solder job, until I connected the hmd, and nothing happened, wasnt recognized at all. So, I disconnected it and connected a usb flash drive, which blew up immediately. I checked the card again and noticed the inverted connector and soldered it properly this time.Checked with another flash drive, and worked ok. Tested all other ports and all of them were ok. The HMD, however, is recognized but only in USB 2.1 mode, not in 3.0 like before.I disassembled the HMD and checked the PCB, which looks pretty intact. No notieceably burnt components or traces. I opened up the cable connector, which has a pcb and some components, but same here. No burn signs.I have no experience troubleshooting USB issues. I suspect there must be an issue with the usb hub controller (GL3510), but I dont know how to test it.If anyone could walk me through it, I would really appreciate it.Attached are the pictures for the USB + HDMI (single) connector and both sides of the main pcb.

author: joystik
author_rank: Contributor
timestamp: March 12, 2020, 05:12:11 pm
content: Ok, so I have looked all over google and have found the GL3510, but it is QFN64. However, the one on the board seems to be QFN48. What are the chances that the old chip may be compatible pin for pin with the newer GL3523, which does come in QFN48?
Help diagnose Sonic Gear 2.1 woofer no bass - Page 1
Forum section: electronics / repair

author: Mikey5791
author_rank: Contributor
timestamp: November 10, 2020, 10:15:00 am
content: Yesterday when i switched on my pc to play some mp3 on this speaker, i noticed the music is coming from two side speakers but the bass(woofer) speaker no sound. Normally the bass will "pop" pump out some vibration. I fed dc3v to woofer speaker red and black wire at sp near cap c23, it had some speaker crackling sound. Fyi, the woofer speaker positive side is traced to 4th leg of Tda2030 audio power amp at the bottom middle of img095833 while negative side is traced to yellow 104 cap at c27.I opened up the inside and checked pcb(img 095833) on ac input got 12.6v at left side big cap(near J2) but no ac detected from the rightside big cap. They are both 3300uf 25v electrolytic cap. Using my cap meter, the leftside cap measured 3330uf while the rightside cap measured 2780uf.Using my dmm, i do voltage check at 8 pin amp 4558 (those 2 pcs on heatsink) by positive red probe on pin 8 and negative black probe on pin 4. Got 18.7vdc on both amp.Another voltage check on tda2030, positive red to pin 5 and black negative to pin3 on all 3 pieces shown 16.3vdc. is this good?I did 200ohm resistance test on those tda2030 by pin4 output to pin3 ground, the tda2030 near subwoofer speaker line showed 5.4(is this low?). The other two tda2030 on heatsink showed high resistance(1) and i can feel the heat sink warm to touch during power on voltage test.Appreciate very much for anyone kind comment and suggestion on making the bass to come back again. Thank you in advance.

author: Mikey5791
author_rank: Contributor
timestamp: November 15, 2020, 11:40:53 pm
content: Also checked the control board where the volume, treble and bass pot are located. During main power on, i use my finger to touch lightly on the vr3 bass white wire and able to hear hum from the bass speaker. Tracing back the white wire of vr3 bass pot is connected to pin 1 of tda2030 near c23. This is the woofer ic. Using dc resistance scale on my dmm, i put positive probe on pin 1 tda2030 (input pin) and negative probe on centre tap of transformer black wire, then turning the bass knob to minimum anti clockwise. The resistance reading is zero. Then i slowly turn the bass knob clockwise to max bass, the dc resistance goes up to 48k ohm. Looks like the woofer ic input pin is working.Anyone out there can help to guide me on what to check and to do next?I am really out of clue now.
Help Diagnosing ASRock Taichi X570 Motherboard - Page 1
Forum section: electronics / repair

author: AlexForTheWin
author_rank: Newbie
timestamp: December 21, 2022, 03:26:08 am
content: Hi all! I picked up a nonfunctional ASRock Taichi X570 motherboard that someone threw away. My main goal is it to repair and use it. But even if it's not possible, I'd like to learn about the process.I'd very much appreciate some guidance.Here are the steps I've taken to diagnose the board:When I initially tried to power the system on with the CPU and some memory, it would spin the CPU fan for a fraction of a second before shutting off. No POST code. I tried with two different power supplies that worked in other systems. So its not the power supply. And the CPU is brand new so it can't be that either.Next step was to take off all the shroud pieces to get a better look at the board. To my surprise, now the CPU fan runs and the board displays the code 00 (fault with the CPU.)I couldn't see any obviously blown components. So I pulled out an out analogue ohmmeter and started probing capacitors.There is a cluster of 5 capacitors near the CPU power connectors (seen in image 5.) I measured the resistance between each lead and ground. The negative leads all read 0 ohms and the positive around 12 ohms. The resistance across each of these capacitors is also around 12 ohms. The resistance isn't rising like you'd expect when the capacitor is charging. Is the 0 ohm read indicative of a short on the board?There is a line of 6 capacitors by the motherboard connector (seen in image 4.) Probing these gave similar results. All the negative leads read 0 ohms. Two of the positive leads read 3 ohms and other four read 12 ohms. This has me confused, because the motherboard can power the lights, CPU fan, and the BIOS chip. Are the capacitors unrelated to the parts of the board receiving power?Lastly, I probed the 17 capacitors surrounding the CPU (seen in image 2). Again, their negative leads all read 0 ohms. The positive leads read 2 ohms and the resistance across the capacitors also read 2 ohms. As a sanity check, I probed random capacitors around the board. And some of them had reasonable resistances on the negative lead between 10-20 ohms.I don't know what the next step is. I couldn't find any board schematics. I'm guessing I follow the traces on the board and probe other components.Where should I be looking now? Any suggestions appreciated.Thank you.

author: coromonadalix
author_rank: Super Contributor
timestamp: December 21, 2022, 11:14:20 am
content: you miss all the heatsinls on the photoThe supply section and the chipset one, have you removed them ?could be a failed bios update ?

author: AlexForTheWin
author_rank: Newbie
timestamp: December 21, 2022, 11:02:33 pm
content: Yes, I removed them to get a better look at the board. Figured it wouldn't get hot enough to cause damage if the CPU doesn't run.It was the BIOS, as you said! The fix was as simple as performing a USB flashback. Not sure if the BIOS was corrupted or if my CPU was not supported by the original BIOS version.Thank you!
Help diagnosing DC Motor Speed Controler - Page 1
Forum section: electronics / repair

author: gilligan
author_rank: Contributor
timestamp: November 15, 2019, 11:02:37 pm
content: It was blowing fuses.Put the meter to it and the center pin of these "Mosfets"? are shorted to each other, which is the AC line... which would blow fuses obviously.Looking around I can't really find the datasheet on that A69104 but looking at the rest of the circuit to see if it is something else (because both of them are shorted from center leg to left leg) I find that the MOV is shorted as well. This is going between the two center pins which would explain why they are shorted. Maybe the left and center should test shorted on that A69104?I know these aren't the best pictures but it's what I got right now.

author: Andy Watson
author_rank: Super Contributor
timestamp: November 16, 2019, 12:27:53 am
content: A69104 - they're not MOSFETs, they're SCRs, thyristors.https://www.radwell.co.uk/en-GB/Buy/KB%20ELECTRONICS/KB%20ELECTRONICS/A69104Allegedly the same as a S4020Lhttps://www.futurlec.com/Diodes/S4020L.shtmlI would expect to measuresomethingbetween the gates and cathodes - it depends on the circuit.Quote from: gilligan on November 15, 2019, 11:02:37 pmAre the SCRs still shorted when the MOV is removed from the circuit ?

author: gilligan
author_rank: Contributor
timestamp: November 16, 2019, 09:00:16 pm
content: Didn't have my desoldering iron with me, will pull it next week and see.I did find a thyrister datasheet when I was googling the part number, guess I want wrong to take a look at that.Thanks

author: gilligan
author_rank: Contributor
timestamp: November 20, 2019, 02:48:09 pm
content: Ok, so the MOV is NOT bad, it reads wide open with a DMM.The SCRs are still shorted with the MOV removed from the circuit.

author: gilligan
author_rank: Contributor
timestamp: November 27, 2019, 10:06:53 pm
content: Bump
Help diagnosing UNI-T UT139C - Page 1
Forum section: electronics / repair

author: Ragnarokkr
author_rank: Newbie
timestamp: July 11, 2019, 03:39:35 pm
content: Hello,I have an issue with my UT139C where I can't couple into the AC metering modes, pressingselectonly gives a bit higher pitch beep and as shown in the attached picture, the LCD goes all in.Funny thing is that it only affects the AC modes, DC works fine as far as I am aware. Board and contacts have been cleaned with PRF6-68, original fuses are intact.I'm totally at a loss, anyone able to help?

author: Ragnarokkr
author_rank: Newbie
timestamp: July 16, 2019, 07:49:57 am
content: Bump
Help drivers Tektronix TDS5000 (NO B) for Windows 2000. - Page 1
Forum section: electronics / repair

author: Ivan_Vetrov
author_rank: Contributor
timestamp: June 02, 2017, 01:08:14 am
content: I try to replace the motherboard on a chip 810. Installed the Intel G865GLC board gave a PCI IRQ routed error 02:0f:00 . I took another motherboard Gigabyte GA-8IG1000MK , the error disappeared. Now it's problematic with the drivers of the Tektronix interface Windows 2000. The front panel was installed using the 5054B .The front panel installed . Drivers PowerPC from 5054B not work . Now I'm looking for a driver board PowerPC from TDS5000 (not B) . Please , if anyone has a TDS5054 (not B) Windows 2000 copy these drivers to me .

author: wxddjc
author_rank: Newbie
timestamp: November 29, 2020, 03:20:15 pm
content: I have TDS5054（No B）ISO ，but I don't know how to send to you.

author: Wahyueko
author_rank: Contributor
timestamp: August 09, 2022, 10:00:11 pm
content: Can you send for me?

author: coromonadalix
author_rank: Super Contributor
timestamp: August 09, 2022, 10:11:35 pm
content: use a file sharing site ?? onedrive account, google drive ?? mega ??