hybridfree/eevblog-posts huggingface dataset:
[fixed] repair HP 8662A Synthesized Signal Generator, power down - Page 1
Forum section: electronics / repair

author: tagchen
author_rank: Contributor
timestamp: January 14, 2020, 01:52:09 pm
content: the generator was on the shelf for a long time and was for waste.Error, very short reaction after use power switch. many of HP or Agilent tools always power on in standby power supply, same her.i have the operator and service manual part II, part number 08662-90069 from april 1999 (supersedes juni 1996)deviceinsidepower supply,second error in my device is the green transformator on A7A3. this solder pads needed resoldering, some of pins lose connection.schematic, error detectthe 5.2V Overvoltage fed from secandary transformator over current sense resistor. if this not running, nothing running.A7A2 is the dedicated power secure board (today is one chip), but in my device was the error in this.TP3 needs high if all correct.to fix needed that the device can start up. to do that needed to start up the driver flip flop. but her is blocked on board A7A2 NOR 14025 (U5B Pin3,4,5 needed low, red marked), from A7A1 High voltage shutdown (9,5V shutdown, TP6) and (5.2V, TP1) Overvoltage detector. Duty cycle generator is working fine.the thyristor q19 goes up if detect correkt voltage from A7A3 transformator 5.2Voltage sense and put down to LOW, but my was defect.But for me i solder an switches inside to disconnect q19 and high voltage detect and but 5.2v from external power supply and pull the NOR up and pulsed the transformator correctly.i changed the caps to long life new one.Q19 -> part nummer 1884-0201, 2N5061U7 -> part nummer 1820-1745, Nor 14025U3 -> part nummer 1826-0192, LM320H-15power, detect card with upgrade two switches to fix the error A7A2.test with other cards outside, power card.i give in the 5.2V for Overvoltage detector, if the voltage is to low on R12 A7A2 -15V (U3 give -14.8V and first i think was good, later i change in new one and -15V perfect)bypass highvoltage detect with switch to GND.ok device is running and measure more. Q19 test outside and doent work, changed in new.After that, the device cant power up without 5.2V external, tested some oft elements and change some caps, nothing. Later i changed U3 -15V and all was fine.schematicsmall battery fix

author: tagchen
author_rank: Contributor
timestamp: January 14, 2020, 03:09:34 pm
content: A7A2A7A2 part listA7A3 block
[fixed] repair HP 8720B Network Analyzer, power down, display rotate - Page 1
Forum section: electronics / repair

author: tagchen
author_rank: Contributor
timestamp: January 14, 2020, 11:45:54 am
content: the HP 8720B Network Analyzer has power down after power lost inhouse. Sometimes the display rotate 180° (with assignment from side buttons).first open device and check for odor and defects. nothing.disconnect cableClean and Gage all Connectorsstep by sep one card out, see wich card is the problem.in me case nothing, after clean and reconnect all is running.for display error (rotate 180° with assignment of front buttons, overhead install?)change some small caps on cpu board and digital board.https://doc.xdevs.com/doc/HP_Agilent_Keysight/HP%208719D,%2020D,%2022D%20Service%20guide.pdf
[Giveaway] FX-888D Mains Board Replacement - Page 1
Forum section: electronics / repair

author: gbrown128
author_rank: Newbie
timestamp: January 16, 2020, 02:53:13 pm
content: Hi Folks,I recently had to replace the mains power board mounted to the transformer of my FX-888D. Rather than pay the £20 to Hakko I tacked my own design onto a JLCPCB order. The design is up here, along with some photos:https://github.com/gbrown128/FX-888D-Transformer-PCBI have 4 spare, so I thought I'd offer to post them out to anybody who can use them. Drop me a message and I'll post them out from the UK free of charge!As to why I needed it - I have a 120V model, so it runs off a step-down box. That box also has a 240V outlet on the front that accepts the US plug!I didn't have a good soldering iron to swap out the fuse with, so traces got ripped and it was all a bit messy!I hope this is useful to someone!
[HELP] 20011 CIVIC instrument cluster How to Light-up the LED indicators? - Page 1
Forum section: electronics / repair

author: ActiveRegion
author_rank: Contributor
timestamp: May 31, 2022, 04:00:17 am
content: This may sound basic to others. I have something in mind but i want to get others opinion as well to reinforce it.So basically, i have a civic instrument cluster detached from the car.I just want to check ALL the LED indicators if they are working. I want to know where to hook-up the 12V power supply so all the indicators light up.I have theschematics, and thepin-out(36 pins), and thepic of the instrument cluster(i got from the internet) showing all indicators lighting up with 2 wires connected at the back. Which tells me, this can be done. Also, the pin-out shows the ground connection but there is no +12V or BATT connection as most pin-outs do, this is where all my confusion and hesitation comes from.IMAGES OF THE SCHEMATICS AND PINOUTS:https://imgur.com/a/j4MHImySo my mind tells me i connect the +12V line of the Power supply to the White Line since it is where all the Anode of the LED is connected as shown in Schematics Page 2 and 3. I just want people to agree on this as well? What do you think. Thank you.

author: Kim Christensen
author_rank: Super Contributor
timestamp: May 31, 2022, 04:47:37 pm
content: Quote from: ActiveRegion on May 31, 2022, 04:00:17 amIt looks like pins 17&18 (brown & white) are the ignition & battery (+12V) supply lines with 15&16 (black) being ground. Most of these instrument clusters will light up all lamps for a few seconds and zero the gauges when 1st powered on. So with ground on pins 15&16, I'd apply +12V to pin 18 (white BATT) and then also apply +12V to pin 17 (brown IGN).
[Help] Absaar / Halfords 12V battery charger - Page 1
Forum section: electronics / repair

author: 1980s_john
author_rank: Contributor
timestamp: January 26, 2025, 08:29:16 pm
content: Hello,I've got a faulty 12V lead-acid battery charger, it is branded Halfords but the PCB is made by Absaar, and has part number FA31. It is labelled as a a smart charger that can be left connected to act as a battery saver. The mains transformer outputs 14V AC as an input to the PCB, and the right hand green power LED comes on but there is 0V on the output. I've checked all the big rectifier diodes OK, the circuit looks quite involved, the main active components I've noted as:LM324N - op ampLTV827 - dual opto couplerBUZ11 - MOSFET (three in parallel)BC327 - NPN transistor (three)various zenor diodesHas anyone seen this charger circuit before please? I was thinking of tracing out the circuit to try and help diagnose the fault(s).Thanks,John

author: Poroit
author_rank: Frequent Contributor
timestamp: January 27, 2025, 05:41:05 am
content: G'day 1980s_john,I have not seen your model but there are lots of similar circuits online that should guide you.Does the LM324 have its Supply Voltage?

author: 1980s_john
author_rank: Contributor
timestamp: January 27, 2025, 10:12:35 pm
content: Thanks, I checked the LM324 and no it didn't have any supply voltage. Turns out it is fed from the battery out leads - so no battery = charger not enabled. Feeding some volts (via a blocking diode) into the battery leads and the charger started up fine. I can't find the instructions for the charger, but it seems common that intelligent chargers need to be connected to a battery before they start up.Thanks again for the nudge, sorry to have thought the charger was faulty - just user error!Regards,John
[Help] Dell XPS 9560 Not booting | No-Battery-Voltage/Charger-is-not-recognized - Page 1
Forum section: electronics / repair

author: IamSynthetiC
author_rank: Regular Contributor
timestamp: December 28, 2021, 06:03:51 pm
content: Greetings,Recently i traveled to another city and i took my laptop with me. I used it there and it worked fine up until the last day when i packed up and took the ferry back home ( Laptop was charged 100% and shoved into my backpack ). While on the ferry (6h after packing aprox. ) i took my laptop out only to find it hot to the touch, and it would not boot (the light would come on for 1-2 seconds, sometimes more, and then it would die).While home i measured the battery only to find it at 0V (BMS probblem ?). I tried to charge the latptop with my DELL charger and it would not charge. I tried taking the battery off and itwould bootwhile plugged in, but itwould not reconize the charger, and it would drop the CPU clocks to 0.6 GHz.I've read that a Dell laptop does not boot with a dead battery, and so that would seem to be the source of my problems. But the fact that the charger is not recognized worries me because it would not charge the battery, good or bad.So i am left with four possible theories :The battery is dead, and the charger is just glitchingThe charger is dead (conveniently) and it would not charge a discharged batteryBoth are deadDC Plug problemas far as the DC Plug is concerned, i tried to "spy" on the data line of the charger with my osciloscope but i saw no communication. I know it uses single-wire-protocol but i could find no info on this specific application.What do you think ? Anyone has any similar experience?Thank you for your time.Happy Holidays.

author: abdulbadii
author_rank: Frequent Contributor
timestamp: December 29, 2021, 07:36:41 am
content: must work identify BMS or get a nearest schematic, did find the burnt short ?# 1 must be dropped as it's too absolutely yes
[HELP] Does anyone have a Agilent DSO80k that can help me out? - Page 1
Forum section: electronics / repair

author: sprit
author_rank: Regular Contributor
timestamp: October 09, 2025, 02:20:43 pm
content: Hello everyone, have a nice day.Is there anyone here who is using the Agilent DSO80K series who can take a picture of the infiinium drivers for me?I have a DSO81204B that has a broken motherboard (PC), I am trying to repair it by replacing the motherboard but I am having some Driver issues. I may be missing some drivers. I can't remember what drivers my old one was loading so I need someone to take some pictures for me so I can refer to them.The drivers I got from an old backup on my hard drive. A member who has a DSO8k took some pictures for me but I am not sure if it is the same for the 80k series. It seems like I am missing some drivers or they are missing so I need your help.Below is the image that a member who owns DSO8k sent me, now I just need to find an image of the DSO80Kto compare.Thank you very much everyone.Feng

author: sprit
author_rank: Regular Contributor
timestamp: October 11, 2025, 11:14:40 am
content: :'( Can anyone help me?

author: coromonadalix
author_rank: Super Contributor
timestamp: October 11, 2025, 12:48:57 pm
content: be patient and politeyou have already some threads going on, do not push or put pression on members here, if some can or will help you will know

author: Sorama
author_rank: Frequent Contributor
timestamp: October 11, 2025, 01:00:52 pm
content: If there would be a driver missing, you would see some devices with question mark.Do I don’t think a missing driver is the issue.

author: coromonadalix
author_rank: Super Contributor
timestamp: October 11, 2025, 01:06:15 pm
content: yes theses shown drivers are installed and not missingthere are programs who will backup drivers and export them, that way you can re install somewhereon his other threads he need to find the related motherboard drivers, it is possible if you calm down and do proper search(s), it's a pc based scope, if the pc is not right scope will not work

author: sprit
author_rank: Regular Contributor
timestamp: October 11, 2025, 02:37:18 pm
content: HiAs you can see in the picture I attached the driver is called Infiinium Memory Controller, and it has 5 loaded. I searched some more threads about the 54831d and 54845, they also have additional drivers for the channels (4 channels 4 memory drivers).I am just looking for pictures of these DSO80k devices just to compare with mine to see if there are any differences.I think it's definitely a driver issue. I've modded the drivers for newer hardware and it worked (partially).I've checked all the hardware involved and made sure they're working properly. Installing extra or missing drivers will cause BSOD or failure to boot. So I just need someone with a scope like this to take a picture of which infiinium drivers are loaded after booting, that's all.Thank youFeng
[HELP] Hantek DSO5202P bricked – looking for kernel.bin, rootfs.ubi, recover.ubi - Page 1
Forum section: electronics / repair

author: crazybike63
author_rank: Newbie
timestamp: September 10, 2025, 04:18:57 pm
content: Hello everyone,I recently acquired a used Hantek DSO5202P digital oscilloscope that was left in a bricked state after a failed firmware update. I have full access to the UART console via J801 and can enter the U‑Boot recovery menu (EmbedSky Bootloader).Unfortunately, the .up update file from Hantek’s official website is not usable via the bootloader — it expects raw firmware files:kernel.binrootfs.ubirecover.ubiThese can be flashed via the U‑Boot menu options , , , and would allow full system recovery.If anyone has a dump of a working DSO5202P, or can extract these files from their device, it would be incredibly helpful.I’d be happy to flash the official firmware .up once the system is running again.Thank you in advance! 🙏— User trying to rescue a perfectly good oscilloscope from the bin

author: gnif
author_rank: Unknown
timestamp: September 10, 2025, 05:42:04 pm
content: I don't have one of these devices, but I did a bit of digging anyway for you.The update from Hantek is .tar.gz file encrypted using gpg with password `dso5000p`, this password is specific to updates for this series. Unfortunatly upon unpacking it it does not contain what you are looking for, it literally is just a update that copies a new version of several files to the internal file system.In short, you're going to need a full firmware dump to recover this.
[help]DEVICE FOR MAGNETOTERAPY - Page 1
Forum section: electronics / repair

author: phantom
author_rank: Contributor
timestamp: May 29, 2025, 11:10:24 am
content: hi to all, i'm trying to fix this device...(i'm a newmbie of electronics)here you can find the manualhttps://www.manualslib.com/manual/3275354/Igea-Biostim-Spt.html?page=16if you go to the troubleshooting page, you can find my error: the last one.i've check the solenoide and it is ok. with or without the solenoide, i've always the same error.i think i should see something with the probe of the oscilloscope (that i'm trying to learn) on the solenoide. but i can't see anyhing:the solenoide is directly connected to an IGBT (Good)https://www.alldatasheet.com/datasheet-pdf/pdf/163161/STMICROELECTRONICS/STGF10NC60KD.htmland it is connected to an Half-Bridge Gate Driverhttps://www.onsemi.com/download/data-sheet/pdf/fan7380-d.pdfthe driver is directly connected to the processorhttps://www.nxp.com/docs/en/data-sheet/LPC1759_58_56_54_52_51.pdfi think i should see some pulses on the pin 2 of the fan7380. but i can't see anythingi'm not able to do anything more....is it game over? should i check something else?thank you very muchps the board is powered @12v/0,8 a

author: gunther_p
author_rank: Newbie
timestamp: June 13, 2025, 11:42:02 am
content: Hi,Quoteso the problem is the "red fixed light and a acoustic signal"?Quotehow did you check?The solenoid is J2?If I interpret the images in the manual correctly, the cable soldered at J2 connects to a plug and then to a coil. Could there be a poor connection or something similar at the plug?
[help]TONOMETER! - Page 1
Forum section: electronics / repair

author: phantom
author_rank: Contributor
timestamp: May 23, 2025, 09:09:40 am
content: hi to all! i'm trying to repair this tonometer...i don't know the history...problem is that numbers don't appear at all.the double led when i power on the board, is flashing...so i think the motherboard is on and workingyou can read the manual herehttps://www.manualslib.com/manual/1722075/Haag-Streit-At-900-D.html#product-AT%20900%20Dit says"Switch the tonometer on by pressing the functionkey briefly. We recommend checking the display ele‑ments regularly to ensure they are functioning whenswitching the tonometer on. [8.8.8] appear shortly andthen each individual LED segment lights up, follow‑ing by the software version: a 3‑digit number. At thesame time, the red and green displays will flash alter‑nately."i've test all 7 segment numbers and are oknumbers are controlled byMCU MSP430F437i have 3,45v on pin 1 and pin 52transistors seems good , resistences too...is it very unlikely, for me, that 3 transistor are broken at the same time...i don't know what can i check.....this is the best i can do with my knoweledge...can you help me??P.S. sorry for my english

author: daisizhou
author_rank: Super Contributor
timestamp: May 23, 2025, 11:40:02 am
content: If you wish to have your repaired, it is recommended that you obtain a Haag-Streit AT 900 D service manual.Usually Instructions or Use Manual focus on usage.good luck

author: phantom
author_rank: Contributor
timestamp: May 23, 2025, 01:02:09 pm
content: thank you for your reply.impossible to find service manual. it's because of this, that i've open this thread

author: daisizhou
author_rank: Super Contributor
timestamp: May 23, 2025, 01:26:08 pm
content: Quote from: phantom on May 23, 2025, 01:02:09 pmBiomedical engineers usually haveMaybe this is a wrong way of suggesting

author: darkspr1te
author_rank: Frequent Contributor
timestamp: May 24, 2025, 09:26:18 am
content: If you have a scope then probe the output pins from the mcu before the resistor, after, after the transistor and see if it does do POST signalsdarkspr1te
[HELP REQUEST] BIOS Password Reset On Toshiba Satellite Radius E45W-C4200X - Page 1
Forum section: electronics / repair

author: Donllc
author_rank: Newbie
timestamp: June 13, 2020, 03:58:17 am
content: I have a laptop that I am trying to help a family member get back into since they forgot their BIOS password (boot) but I can not locate the jumper pins to reset it.I've also tried letting it sit off the power cord for a few days (no cmos battery and internal battery is dead), holding down the shift key on boot, and using TOSHIBA/Toshiba/toshiba as an override password without any luck.Am I missing something?

author: coromonadalix
author_rank: Super Contributor
timestamp: June 13, 2020, 02:25:40 pm
content: I think you posted on many websites, you got no answers ?do you have something like this on your mobo

author: LDMarin
author_rank: Newbie
timestamp: September 22, 2020, 10:33:27 pm
content: Just short JRST2501 while booting and it will wipe the password. Hope it is still useful for you.

author: Donllc
author_rank: Newbie
timestamp: September 24, 2020, 11:00:47 pm
content: Different model.

author: Donllc
author_rank: Newbie
timestamp: September 24, 2020, 11:04:20 pm
content: I can't express how much I appreciate your response. Not sure how I missed those pins but nonetheless you had the working solution to this problem. Once again thank you, and I would also like to suggest making a Youtube channel to share this valuable info or at least uploading to ifixit.com!!
[in repair now] repair HP 8114A High Power Pulse Generator 100V/2A - Page 1
Forum section: electronics / repair

author: tagchen
author_rank: Contributor
timestamp: January 17, 2020, 09:29:10 am
content: hi, actually, or more an long time repair, i repair an HP 8114A.problem, selftest "no trigger signal for output board" , output relais doesnt work (generator say its on, but is off).i use the generator for extremly high power (...-120KW) LIDAR prototypes and the problem is you don't get another generator for money either, mostly low power.i measure the procedure from service manual with sperated transformer and scope but the big white transistor and GND resistor blow up.change transistor, but i have no idea about resistor (test 1K), sme problem with selftest.after that, i pick out the voltage boards and measure testpoints, -17V and 12V are mistake. after that checked power supply pcb outside and all voltage are ok--> must problem on output board.i will spend some money for schematic and check again. acually no ideas that i can do next. and other projects.

author: Mike112
author_rank: Newbie
timestamp: February 04, 2020, 04:35:48 am
content: Did you find a schematic? I'm working on fixing the same unit with the same problem right now and am looking for a service manual

author: tagchen
author_rank: Contributor
timestamp: January 21, 2021, 12:38:31 am
content: no. I have contact HP / Agilent but she havent the shematics. So cant buy.
[Longwei K3010D] Max voltage has dropped from 30V to 11V - Page 1
Forum section: electronics / repair

author: czesio666
author_rank: Contributor
timestamp: February 26, 2025, 01:12:22 pm
content: Hi everyone.I have a problem with Longwei K3010D power supply. I have made some minor repair inside, just tighten front connector. Then I have tried to power it on and residual-current device cut off the power. Probably I have made short circuit with metal cover. Removed and assembled once again. Now power supply is working but I cannot adjust voltage to 30V. In whole range of knob adjustment it goes only to 11,5V. Adjustment is linear and there is no dead zone.Any ideas where could be the problem? I guess that somewhere could be a faulty joint.MCH K305D DC POWER SUPPLY schematic
[solve]CPU atx power supply soft start up voltage drop down problem - Page 1
Forum section: electronics / repair

author: AkibUddin
author_rank: Contributor
timestamp: December 13, 2022, 02:41:01 pm
content: Hi,try to find out ee 19 Flyback Toroidal High Frequency Transformer secondary soft start up voltagedrop 12v to 150mv. Now confusing about it, cause it is also PWM section from PWM ic using 817 optocoupler , now what i do ?
[Not electronics, but adjacent] Repairing/rpelacing worn knobs - Page 1
Forum section: electronics / repair

author: klausman
author_rank: Regular Contributor
timestamp: May 13, 2025, 07:05:03 pm
content: So I am repairing a Luxman L-215 amp. It's mostly in good condition, but the owner asked me to replace those infernal twist-lock speaker terminals. I can deal with that fine.However, also broken (in away) are the control knobs on the front. They're flaking their lacquer/finish,badly:Any ideas on how to fix this? An original replacement set would be ideal, but that's very unlikely to happen any time soon.

author: thephil
author_rank: Regular Contributor
timestamp: May 13, 2025, 07:22:30 pm
content: The only options I can think of are spray paint and Chinese replacement knobs of roughly the same size.And maybe browseMend it Mark's YouTube channel – if you are lucky you may find a similar situation there.

author: wasyoungonce
author_rank: Frequent Contributor
timestamp: May 14, 2025, 12:02:35 am
content: Aliexpress is your best bethttps://www.aliexpress.com/item/1005007476855828.html?src=google&pdp_npi=4%40dis!AUD!0.90!0.72!!!!!%40!12000040911290948!ppc!!!&albch=shopping&acnt=272-267-0231&isdl=y&slnk&plac&mtctp&albbt=Google_7_shopping&aff_platform=google&aff_short_key=UneMJZVf&&albagn=888888&ds_e_adid=738012934484&ds_e_matchtype=search&ds_e_device=c&ds_e_network=g&ds_e_product_group_id=2403836566736&ds_e_product_id=en1005007476855828&ds_e_product_merchant_id=5408146766&ds_e_product_country=AU&ds_e_product_language=en&ds_e_product_channel=online&ds_e_product_store_id&ds_url_v=2&albcp=22318332228&albag=177676186793&isSmbAutoCall=false&needSmbHouyi=false&gad_campaignid=22318332228

author: CatalinaWOW
author_rank: Super Contributor
timestamp: May 14, 2025, 04:34:04 am
content: Depends on your skills. If the knobs are sound just refinish. You could probably have an auto body shop so this for you. Broken knob where all the pieces exist can be glued back together and then refinished. If you have one intact example you can resin cast copies or model it and 3D print. Metal caps and rings can be machined and fixed in place.

author: klausman
author_rank: Regular Contributor
timestamp: May 17, 2025, 06:31:41 pm
content: Went with a refinish:The odd rose-color metallic is as close as I could get it to the front of the amp itself. And of course with spray paint, the eternal rule is: make it many very, very thin coats, that way, you don't get runners, and in-between coats, you can do mild corrections with a scotchbrite pad and gentle patience.

author: thephil
author_rank: Regular Contributor
timestamp: May 17, 2025, 07:31:58 pm
content: Wow– great job!

author: CatalinaWOW
author_rank: Super Contributor
timestamp: May 17, 2025, 10:12:30 pm
content: Nice finish. If you are a museum or collector having an exact match to the original is the gold standard, though it may be hard to know what the original was because all current examples are aged. For the rest of us, looking good is the standard and you have more than achieved that.
[Part identification] Siemens PLC output board repair - Page 1
Forum section: electronics / repair

author: Rutherberg
author_rank: Regular Contributor
timestamp: August 21, 2019, 10:18:18 am
content: Hi,I'm on a Siemens PLC output board (board ref 812 2298 01-, PLC model Simatic S5-100U), the "fault" led of that board is on when using the PLC. It is not a slot problem, other board worked fine in the same slot.I identified the faulty part, it is a SMD in parallel with the input cap on the power supply rail, and it is in short circuit.The package seems to be a SOD-80, marked "2222" all around the part. Probably a surge protection part, but I can't find any informations about it.Here are some pictures :https://www.dropbox.com/sh/fn01nqzu8qwz9v4/AACLUskmBHj4l6z6YH_wRcdTa?dl=0Furthermore, the 10A fuse is blown, is there a way to determine if it is a fast acting or a slow blo ?Thanks !

author: goaty
author_rank: Regular Contributor
timestamp: August 21, 2019, 10:50:18 am
content: I guess its a spark gap / overvoltage protection.Reverse polarity protection is unlikely.

author: fzabkar
author_rank: Super Contributor
timestamp: August 22, 2019, 08:22:36 am
content: The adjacent 22uF capacitor is rated for 50V, so that might provide a clue (a voltage measurement would be better). I'm guessing that the arrestor could be replaced with a transient voltage suppressor, eg a TVS diode, transil, etc. However, I would think that gas arrestors would tend to be more robust and more likely to recover from an overvoltage.https://au.mouser.com/datasheet/2/315/ABA0000C1151-947454.pdf

author: Rutherberg
author_rank: Regular Contributor
timestamp: August 22, 2019, 09:30:44 am
content: The power supply module for this PLC is 24Vdc.So a TVS of about 35V should do the trick, right ? Or should I narrow it to near 24V ? It's an output module so there is no ultra sensitive parts on that board...Thanks !

author: Brutte
author_rank: Frequent Contributor
timestamp: August 22, 2019, 09:37:30 am
content: I'd use something that passes around 1mA at rated voltage.

author: fzabkar
author_rank: Super Contributor
timestamp: August 22, 2019, 10:16:35 pm
content: A 24V unidirectional TVS diode will do the job. That's it's standoff voltage. It's breakdown voltage would be considerably higher.I would consider an SMCJ24A or SMBJ24A or SMAJ24A, depending on the physical dimensions.https://m.littelfuse.com/~/media/electronics/datasheets/tvs_diodes/littelfuse_tvs_diode_smcj_datasheet.pdf.pdf
(Possibly) Zener diode identification. - Page 1
Forum section: electronics / repair

author: Aller
author_rank: Contributor
timestamp: February 11, 2023, 08:26:15 am
content: Hi Everyone. I have a shorted diode marked15A 435. It's most likely a Zener, considering its place in the circuit and that it was connected with the anode to the ground. I tried to find its reverse voltage value on the internet without success. Can anybody help? This board is a part of the Caterpillar control system. The board number isCAT 106-1154. Does anybody have any insight on this board? The board doesn't have any designators; in fact, it doesn't have any silk screen. The only symbols (generic diode and the "+" signs next to capacitors) are etched from the copper plane and are (I feel) for polarity only rather than any specific markings. Pictures attached. The diode's very bad quality (dark) photos are due to the barely readable markings, so I had to play with lighting under the microscope to show anything.

author: fzabkar
author_rank: Super Contributor
timestamp: February 11, 2023, 04:30:37 pm
content: It's probably a 15V unidirectional TVS diode, something like a P6KE15A.

author: MathWizard
author_rank: Super Contributor
timestamp: February 11, 2023, 07:56:28 pm
content: Is that a SMPS there on the right, that transformer and diodes and mosfets, and a controller chip?In computer SMPS, I've seen a lot of 18 and 36V protection zeners in gate drive circuits, auxiliary low voltage windings, and some of the sensing circuits. But there's also reverse polarity diodes around some of the main transformer windings.
[QUESTION] Defective Factory CH341A, which changes to do? - Page 1
Forum section: electronics / repair

author: md5001996
author_rank: Newbie
timestamp: July 09, 2024, 07:13:32 am
content: Anybody know which components to replace?I see that Quartz crystal oscillator is 13Mhz (it says TXC 13.CUS37) must be 12Mhz, and C5 must be replaced with a 15~30pf capacitor (because that 0 ohm is a resistance acting as bridge). Although i do not know the size of C6 capacitor (must be 20pf)Also, i dont know if C4 has the correct capacitor, because is small and must be 4.72nf.Can someone validate me if it will work as I have it? and if not, what components to change besides the ones I named?Maybe I'm wrong, that's why I ask here to know what to do really and not to lose my CH341a that I can not return to Amazon, since it arrived to me after 2 months.Things I understand I should do after changing the wrong components:* Do the mod from 5.5 to 3.3v by installing a switch that connects the VCC leg of the CH341A and switch between 5v (C2) and 3.3v (C1).* The WP /HOLD mod (which I am not clear on what it fixes, but I would like to make the mod to ensure more compatibility). Although it seems that my ch341a has different tracks than other users, so i will need a new image to do correctly the mod in my ch341a. Besides that, I don't know which resistor value would be the ideal size for the mod ( 472, 271 or any libreboot recommended between 1k to 10k ohms ?)Swich mod and wp /hold mod photos are not mine (it's todo photos). Any help will be appreciated!

author: m k
author_rank: Super Contributor
timestamp: July 14, 2024, 05:42:27 pm
content: https://pdf1.alldatasheet.com/datasheet-pdf/view/1132609/ETC2/CH341A.html
[RIGOLDS1102E] Rotary/Buttons repair and cooler removal - Page 1
Forum section: electronics / repair

author: zulunation
author_rank: Contributor
timestamp: April 25, 2022, 11:03:58 am
content: hiall.After almost 10 years of using DS102E i faced with a problem with knob rotators and buttons.So all they should be replaced.I wrote a letter to rigol support center asking for repair parts but received no answer.Maybe anyone knows part numbers for rotary knobs and buttons?Also i would like to share my idea of replacing a cooler inside oscilloscope with a huge radiator.i have removed the cover and it seems that the only warm part of oscilloscope is PSU.I am not 100% sure about that. I don't have any infrared camera to check that.Maybe anyone has any information about that?It would be nice to remove cooler and make it completely silent.I see that tektronix scopes within the same category are without coolers. That gives a hope.DS1102E is really good scope for me the only drawback is cooler noise...Maybe someone have upgraded it?
[SOLVED] HP 54645A PSU fault - Page 1
Forum section: electronics / repair

author: andymcc
author_rank: Newbie
timestamp: May 27, 2021, 01:33:09 pm
content: I just wanted to leave a note here in case it helps anyone in the future searching for a fix. The other day my 54645A scope failed to power-up, without any warning. It seemed to be a PSU fault.Via a lucky stroke I came across an 11 year old post on an Agilent forum saying the poster had found resistor R27, 330K/~600mW had gone high and replacing it fixed the PSU.Sure enough, that was the exact same fault and fix for me !I think it's possible the same PSU may have been used in other 54600 series models, so I'll list them here for search purposes:54600B54645A54645D54602B54610B54615B54616B54616C

author: xavier60
author_rank: Super Contributor
timestamp: May 28, 2021, 01:49:19 am
content: Where I live, the 240VAC mains is hard on HV resistors. I used VRW37 resistors in my 54645A,https://au.mouser.com/datasheet/2/414/VRW-1528257.pdfFrom memory, there is also a 1MΩ resistor that can fail. I'll double check the next time I open it up.
[Solved] ChangHong LCD/LED TV boot loop repair. - Page 1
Forum section: electronics / repair

author: shakalnokturn
author_rank: Super Contributor
timestamp: October 28, 2021, 08:53:34 am
content: This 28" LCD TV had been picked from the dumpster about a year back.When first powered it worked well, after a few hours test on a restart it went into a boot loop. Sometimes leaving it loop long enough it would finally work.The board used in this TV is TP.SIS231.P83.A quick search on internet returned that corrupt / defective SPI flash was common, one of many reports here:https://www.eevblog.com/forum/repair/broken-tv-(teac-lev3992fhd)/msg1084131/As the symptoms, matched mine I went looking for a firmware dump and new EEPROM.The ChangHong website has the latest firmwares updates available if you have the barcode and serial number on the back of the TV, mine didn't. Looking through pictures on internet I found a couple of serial numbers of similar 28" models and downloaded what seemed to be the right firmware. Updating the original EEPROM through USB made no difference so I wrote a new EEPROM with the universal programmer. TV would come on with access to menus but DVB-T reception was unusable my conclusion was that the FW wasn't the right version... TV got pushed aside for a year or so...Clearing-up a little the other day pushed me to have a last attempt before letting it go for good. This time I started with the basics (as one should rather than looking for the answer on internet before thinking...) and checked the power rails.A couple of LDO regulators had slowly varying 3.3V on their input and not quite stable 2.5V outputs (tested with DMM).I couldn't trace where the 3.3V supply was until I downloaded a similar TV's schematic (TP.SIS231.PT85) which showed that my unstable 3.3V should have been 5V.5V switching regulator was giving 5V, the problem was P-MOS QM32 (WPM2341A) used for 5V standby switching near LVDS connector.
[SOLVED] Tektronix MDO4000/MSO4000 Series Oscilloscope Front Panel Repair – Succ - Page 1
Forum section: electronics / repair

author: Isan
author_rank: Newbie
timestamp: October 10, 2025, 01:38:10 pm
content: Hi everyone,I’d like to share a successful repair story involving the front panel of a Tektronix MDO4104B oscilloscope. This solution is also applicable to other models in the MDO4000/MSO4000 series.The front panel on our department’s oscilloscope suddenly stopped responding. We sent it out for repair, but unfortunately, it came back unrepaired. We were told that the front panel replacement was no longer available and that we should discard the unit — a device worth nearly€20,000!Determined not to give up, we started researching online and came across a helpful thread on EEVblog:Link:-Tektronix MSO4054 - no boot  + not working front panel A special thanks to@dbatorfor sharing key insights that made this repair possible.Symptoms Observed:Front panel buttons and knobs were completely unresponsiveThe oscilloscope booted automatically upon connecting the power cable (without pressing the power button)Diagnosis & Repair:The issue was traced to the front panel microcontroller, which communicates with the main MPU and handles user input. Following the steps in the EEVblog thread and adding some of our own, we were able to successfully repair the unit.Repair Guide:I’ve compiled a detailed tutorial including:Step-by-step instructionsHigh-resolution photosRequired software and hardware toolsFirmware and microcontroller programming detailsYou can download the complete guide as a PDF along with all necessary files in the attached ZIP archive.Attachment :-Tektronix Repair Guide ZiP FileContents:Repair Guide PDFFirmware filesReference imagesMicrocontroller programming toolsI hope this helps others facing similar issues. Feel free to ask questions or share your own experiences!Best regards,Iqbal Singh Sandhu

author: coromonadalix
author_rank: Super Contributor
timestamp: October 10, 2025, 02:39:28 pm
content: thks
[trying out ChatGPT] ZyXel GS1005HP PoE Switch repair - scorching hot coil - Page 1
Forum section: electronics / repair

author: faekjarz
author_rank: Regular Contributor
timestamp: March 05, 2024, 06:22:29 pm
content: Gidday, Daves!You're all Daves, as far as i'm concerned.…lovely stuffI'm repairing a ZyXel [CyCell, CyberCell] Switch, a GS1005HP with PoE+ feature.Symptoms:scorching hot coil/inductor (part of the 57V PoE supply circuit), beyond 160°C, adjacent components heat-affectedFor the fun of trying out shiny new tech, i've attempted to figure out the correct coil/inductor, using Microsoft Copilot (ChatGPT). The results are not exactly meaningful, for a novice like me. I've documented my rather turbulent ride on the Fediverse (aka Mastodon), see also the related threadhttps://layer8.space/@platymew/112043595783702798.I do live in Germany, but i'm asking in general: which coil/inductor would qualify as a proper replacement part.If i recall correctly, the guy in the (German, Austrian accent) Video used a 100µH inductor. Even the OEM/ODM left a comment in their Video, mentioning a known issue with certain batches. They didn't quite explain what the actual fault was, though.I'm looking forward to your comments and thoughts.(I intend to re-sell the fixed item on eBay, so my quality standards are quite high - it needs to be reliable - i intend to replace the heat-affected parts nearby as well.)EDIT: the point is, that i really don't know enough about ferrite coils / inductors. The droids i'm looking for have 2 leads, 2 poles, ~13mm diameter, a width of ~6mm, and an estimated up to 1mm² conductor.
(Vintage) Nortronic 811 Sound Analyzer - Page 1
Forum section: electronics / repair

author: arno
author_rank: Contributor
timestamp: June 14, 2019, 05:51:03 pm
content: Dear folks,it is vintage electronics time again. The Nortronic (now called 'Norsonic') 811 sound analyzer is dated around 1975 and can measure sound pressure levels and even room reverb time. See the attached picture. Luckily I have the complete schematic, which is around 30 pages. In there are 20 cards in a row.My unit has an odd issue, which I could not repair: Card no. 20 (see attached schematic) is the so called sample generator, which generates pulses for the (analog!) band pass filters, depending on the frequency you choose on the panel.At room temperature the unit generates almost an rectangle signal. When heating up the marked transistor (AE254) just a little bit, suddenly the card starts working as intended.So my two questions are: Does anybody have a datasheet for the AE253/254 transistors? What could possibly cause this problem? I have already swapped caps, diodes and measured all resistors (they were all good).Thanks in advance!

author: arno
author_rank: Contributor
timestamp: June 30, 2019, 04:45:53 pm
content: Dear all,seems like this will become a bigger project. Have not found the issue yet.I will redraw the whole schematic of the unit with KiCAD, whenever I have some free time.You will find it on github:https://github.com/adaeuper/nortronicStarted with card no. 5 (a 40 dB amplifier) today.Best wishes
**Hantek DSO4254C Won’t Boot – Stuck After USB Recovery Attempt - Page 1
Forum section: electronics / repair

author: j@cs
author_rank: Newbie
timestamp: July 30, 2025, 10:29:57 pm
content: Hello everyone,I recently purchased a Hantek DSO4254C oscilloscope via AliExpress. Upon first power-up, the device showed erratic behavior: the front panel buttons blink intermittently, and the scope randomly reboots or freezes — it never enters a usable state.I contacted Hantek support, and they sent me a USB recovery package. I followed their instructions precisely:Used an 8GB USB stick, formatted as FAT32Copied all provided files to the root directoryInserted the USB and powered on the scopeThe screen shows options F1, F2, F3 — but regardless of which option I press, nothing happens. No firmware update, no boot process, just a frozen screen.Since then, Hantek has stopped responding to my emails, and I’m left with an unusable scope.Has anyone encountered this issue before? Is there any known workaround (e.g., UART console access, JTAG, or internal recovery methods)? Any help or documentation would be greatly appreciated.Thanks in advance!–José Alfredo
0.5 pitch BGA. Reballing the chip or the board? - Page 1
Forum section: electronics / repair

author: Buriedcode
author_rank: Super Contributor
timestamp: December 14, 2023, 06:28:13 pm
content: I plan on removing a memory chip from a phone and mounting it on an adapter board. Without a preheater and decent microscope I can't see me having any hope of soldering the chip onto another phone's doner board, but the adapter board I bought has a footprint for it and nothing else - plenty of space around it and not much ground plane to suck away heat from the hotair.This adapter board already has balls on the pads that *look* pretty neat and level. So my question is, can I just remove the bumps from the chip, using wick to create a clean flat surface, brush with flux and solder onto the new board? Effectively having solder balls on the PCB rather than the chip. As long as the boards balls are even I can't see this being a problem - but I'm not overly experienced with BGA, having only done a few before and only at 0.8mm pitch.My only worry is, I don't know what alloy these PCB solder balls are, so I was wondering if I should just remove those and add my own with a stencil and solder paste (and leaded solder paste just to make life a bit easier).

author: frogblender
author_rank: Regular Contributor
timestamp: June 12, 2024, 02:54:53 pm
content: @Buriedcode... did you attempt this? Transplanting a 0.5mm BGA does not sound like fun. Curious how it went...
1.8v adapter to ch341a, remod WP, HLD via res for QE - Page 1
Forum section: electronics / repair

author: surfwrite
author_rank: Newbie
timestamp: June 09, 2022, 01:42:55 pm
content: How to convert a 1.8v adapter and separate WP and HLD with resistors to VCC to read and write QUAD QEWill it be possible to save a flash dump, because the adapter's transmitter is one way directionalDoes it make sense to remod WP and HLD on both the ch341a itself and on the 1.8 adapterDid anyone have pictures of the WP and HLD conversion via resistors on the 1.8v adapterThanks to you

author: m k
author_rank: Super Contributor
timestamp: June 13, 2022, 10:11:28 am
content: You have to unpack your message a bit.Acronyms are good but problem is that you need a direct hit before message goes through.Seems that here general audience wasn't wide enough.
1 pole or 2 poles switch for small angle grinder - Page 1
Forum section: electronics / repair

author: gg64
author_rank: Regular Contributor
timestamp: December 17, 2020, 07:57:42 pm
content: Hey,I am trying to fix a small angler grinder.I tried to get the OEM part for the switch could not find it (4terminals/2poles Normal Closed, way off center switch).Photos will be provided in the next post.No ground wire is provided and I am not sure why.I found a potential workaround that is to used those kind of microswitch.I found a 10 (3) A 250VAC seller from germany on ebay.Here is the listing:https://www.ebay.fr/itm/323907219752I got some with small lever, small lever with "wheel".I tried two alongside of each other. But it barely working but it would be really handy if I can use only one.(I can adapt it with plastic PCL since this is an air intake the temperature is most likely not going above 62°C anyway).It is safe to only use one pole switch on a small angle grinder ?Or 2 poles switch are meant to avoid giving shock to the user if something goes wrong during grinding ?Thanks you.

author: rvalente
author_rank: Frequent Contributor
timestamp: December 17, 2020, 08:59:52 pm
content: That up to debate but....Usually angle grinders are double insulated devices, so yes, its safe to switch just one phase to turn it of.Being double insulated the protection conductor (grouding) may not be required, that may change from standard to standards but here in brazil is not (also here, the neutral is grounded so is always a low impedance path)If you run on hot + neutral (120ish) try to cut the hot (mains)Many single insulated 230ish appliances only switch one phase like: hair driers, toasters and microwave ovens

author: gg64
author_rank: Regular Contributor
timestamp: December 17, 2020, 09:27:44 pm
content: Hey,here are some photos of the old switch:Does anyone know where I can find one of those ?

author: gg64
author_rank: Regular Contributor
timestamp: December 18, 2020, 12:02:21 am
content: Well I used one switch with a small lever with "wheel" + some PCL plastic + some drilling to make way for the lever + 3 mm steel wire to hold everything together but allowing this to be removed.I think it is turning the right way.Are you guys interested in this thing photos ?EDIT: photos

author: rvalente
author_rank: Frequent Contributor
timestamp: December 18, 2020, 04:34:19 pm
content: For the price of these machines nowdays I think you went the correct way.Here in brazil if the field or the armature windings goes bad its not worth fixing. Usually the next thing to fail are the bearings
1 year old ATX PSU Silverstone ET550-G cannot power on again after thunderstorm - Page 1
Forum section: electronics / repair

author: hansmuller
author_rank: Newbie
timestamp: May 03, 2019, 04:16:41 pm
content: Hello all,The PSU was running when a lightning bolt struck far away. turned off and cannot power on again.so probably overvoltage exposed.I opened the PSU to replace the fuse. it is a ceramic one, there I cannot see on first sight if it is blown. Also removal seems unnecessarily difficult as it is soldered and no holders that may clamp it.Did a sight inspection and did not see anything apparent.As i do not have good soldering equipment, do you recommend to bring it to technician to solder replace the T10A fuse?What else maybe to check before that?with best regardsHans