hybridfree/eevblog-posts huggingface dataset:
Midea Power Control Board from Springer Air Filter - Page 1
Forum section: electronics / repair

author: vidarr
author_rank: Frequent Contributor
timestamp: May 26, 2020, 06:01:43 pm
content: The main board for my air filter broke. I know one resistor was bad and the capacitor next to it released its smoke. I replaced two capacitors and the resistor, but nothing changed, doesn't work.This board is pretty simple compared to other things I tried to fix, so maybe this is a good time to learn how to troubleshoot component to component. I watched a few videos about this type board, but they fixed their boards by changing the same capacitors and resistor I did. Looks like that was the "common problem". I can't find anyone going further than that.Can someone give me an idea about some kind of next step? I circled the replaced parts with new (in red).Thanks!

author: fzabkar
author_rank: Super Contributor
timestamp: May 27, 2020, 02:17:16 am
content: I suspect that the LNK306P may have failed and sent the full rectified mains voltage to the load.There is an application circuit in the datasheet (Fig 5, page 4):https://www.es.co.th/Schemetic/PDF/LNK304-306.PDF

author: vidarr
author_rank: Frequent Contributor
timestamp: May 27, 2020, 04:45:22 pm
content: Thanks for your input. I downloaded the data sheet and checked it out. Of course, it had to be the most complicated part.First, do you think it fried everything after the IC in the circuit? I guess I can try to figure it out with a DMM, but if it is obvious, that would be great to know.Also, on the data sheet, it has L1 an inductor, but on the circuit it looked like a resistor and had colored bands. I replaced it with a 2.2k resistor. Did I make a mistake?data sheet:Inductor L1Choose any standard off-the-shelf inductor that meets thedesign requirements. A “drum” or “dog bone” “I” core inductoris recommended with a single ferrite element due to to its lowcost and very low audible noise properties.Thank You!
MIDI/USB IC ID   HTB03 - Page 1
Forum section: electronics / repair

author: Audiorepair
author_rank: Frequent Contributor
timestamp: October 17, 2024, 07:55:55 am
content: Hi,can anyone identify the IC marked HTB03 in this photo?This is the MIDI over Ethernet part of a horribly cheap chinese piano/mother keyboard the owner would like to get working just as a mother keyboard.Neither functions work at the moment because this IC is shorted.Ta.Edit: Sorry, thats actually MIDI over USB.
Miele Induction cooktop repair KM5731 error 32 - Page 1
Forum section: electronics / repair

author: adam1213
author_rank: Regular Contributor
timestamp: July 17, 2021, 07:49:41 am
content: The cooktop would frequently turn off when turned on and give error 32. Once it had decided to play nice and was powered up it cooked as usual.i found some repair info for it online and it worked a treat. Essentially there were some bad capacitors. Added own picturesI probably should still replace the flat flex cable that looks a bit burned. Its working fine. As I don't have one / know the part for know I just swapped the cable with the cable on the other side of the board in order to get more life out of the parts.for anyone attempting a similar repair a few tips: don't touch the white circles, the bus bars in where the power connects to the board need removing to remove the pcb.I personally decided to go with this capacitorhttps://au.rs-online.com/web/p/aluminium-capacitors/7621689/https://www.stereo.net.au/forums/topic/107339-replacement-or-better-capacitor/https://miele-induction-cooktop-error-codes.peatix.com/https://www.klusidee.nl/Forum/topic/storing-fe32-miele-inductie-kookplaat-km5732.97663/https://www.klusidee.nl/Forum/topic/storing-fe32-miele-inductie-kookplaat-km5732.97663/page-2The cooktop is powered by at ATMEGA32-16AU which features 4 PWM channels, 8 channel ADC (for temperature sensors, reading feedback to determine if there is a pan etc, inductive button interface)
Miele Vacuum Cleaner Problem - Page 1
Forum section: electronics / repair

author: Sefton Dave
author_rank: Newbie
timestamp: October 13, 2022, 10:43:49 am
content: Hi all, this is my first post in the hope that someone may be able to me and maybe educate me!Our Miele Vacuum Cleaner came to a sudden stop the other day. Looking round on the internet I found that a common problem with this make is that the centre pin of the onboard triac blows off the circuit board. On inspection I can see that the centre pin of the BTB16-600BW triac is not connected to anything.My problem is that I cannot find where it was connected, or maybe it is wired correctly, just using 2 pins?Every circuit that I look at uses the 3 pins, A1-A2-GateThanks. Dave.

author: JimmyJo
author_rank: Contributor
timestamp: October 13, 2022, 11:13:14 am
content: The tab of a TO220 package and the center pin is the same piece of metal. In this design, it looks like they are using the tab connection, going thru the heatsink.It also looks like there is a cracked joint on pin 3(right most pin when part numbers are in the correct orientation) of the triac. If you have a soldering iron, reflow all joints with a bit of flux.
Miele Vacuum HEPA TT 2000 / S591 (?) - pulsing motor, fixed. - Page 1
Forum section: electronics / repair

author: EHT
author_rank: Frequent Contributor
timestamp: June 13, 2020, 11:23:47 pm
content: I just fixed this Miele vac; i thought worth reporting because it's worth fixing IMO. The machine is very well engineered and quite easy to take apart. It is also possible to buy various spares, although annoyingly I can't find the front panel which has broken (hence gaffer tape in pic..). The model number plate has worn off on mine but it seems like it is an S591 or similar. This model has an electronic motor speed controller.The fault on mine was that at more than about 1/3 of max speed it would pulse on/off at about 1Hz. To start with I thought it could be physically blocked but turns out it was the controller board.The controller seems to be anST ST7LITE, however, in my model it is an 18-pin DIP so not exactly the same as this one but the circuit is pretty similar to the application circuit on p9.The motor is regulated by a BTB16 600BW triac mounted on a small PCB on the motor. Failure of this is apparently common. I expected a failure of the TRIAC would make the unit completely dead; i checked it anyway using a bench PSU, LED and resistor on the gate. It was fine. New motors are available but of course not economically viable as a complete unit.Next, with ref to the schematic on p9, I found the zener in place of ZD1 isa 24V one. I checked with a scope (isolated scopemeter) and found the voltage on the zener was not 24V, and when the unit started pulsing it was dropping quite low making the VCC supply to the micro go to low, then it would presumably brown-out and restart.Fault was the 220n X2 cap providing the power, it was reading about 100n. Due to the way it was mounted it was necessary to find the exact same part, which isKEMET Part Number: R46KN322040H1M.There are someshowing how to disassemble Miele vacs.
Mijing m-triangel LWS-301 bga laser - Page 1
Forum section: electronics / repair

author: PKTKS
author_rank: Super Contributor
timestamp: April 04, 2022, 07:37:19 am
content: Just came to my attention this small laser bga tool... any solid opinion welcome...Mijing m-triangel LWS-301 bga livre ic dissembly cpu degumminghttps://a.aliexpress.com/_m0n59c6Paul
MILLER BIG BLUE 400PX FAILURE - Page 1
Forum section: electronics / repair

author: HUGOMAN
author_rank: Regular Contributor
timestamp: April 03, 2022, 01:29:21 am
content: Hithere is no welding, after checking the control voltage board i found a short circuit in a diode, but the problem is the Q2 was removed by someone else and i don't know what's the original part it seems a transistor but which reference ?

author: HUGOMAN
author_rank: Regular Contributor
timestamp: April 03, 2022, 05:50:38 pm
content: Hello to EveryoneThe board model is 214945, the damage is in Q2 since it disintegrated with the failure.If anyone has the map available, I would appreciate your cooperation in finding the Q2 part number. Thank you for your attention.Thank YouCordially!

author: PaulAm
author_rank: Frequent Contributor
timestamp: April 04, 2022, 03:18:36 pm
content: At least at some time, Miller provided schematics. I know they'd rather sell you a new board for $2K, but have you tried contacting them?

author: HUGOMAN
author_rank: Regular Contributor
timestamp: April 04, 2022, 05:00:29 pm
content: At least, even i can't find a board schematic, if someone have the same board to see what part number? i do some reverse eng i am sure that it will be a bipolar transistor not mosfet, also this transistor is drived directely by lm555...i just ask if someone has a photo of this board or already have an experience on this board he will know already the part number !Thanks
Miller MIG Welder NOOB Repair Question - Page 1
Forum section: electronics / repair

author: frostheave
author_rank: Contributor
timestamp: November 12, 2023, 11:03:43 pm
content: Hi All, hope this isn't too dumb a question. I'm a noob at troubleshooting and am looking for some confirmation.I have a Miller 350P Aluminum MIG welder with no output to the external push pull gun motor. I found that the negative lead of the motor connects to RC14 Pin6 which connects to Q24 in the attached picture. Does the damage visible to Q24 look like it has caused it to fail?I will be contacting Miller Welding tomorrow to see if I can purchase a schematic, or at least a part number for Q24. Am I headed down the right road?

author: p.larner
author_rank: Frequent Contributor
timestamp: November 13, 2023, 01:13:31 am
content: that q4 looks toasted,no numbers tho,good luck,maybe remove it and test tho with a cheapo chineese component tester?.

author: frostheave
author_rank: Contributor
timestamp: November 13, 2023, 06:19:41 pm
content: Thanks p.larner. I agree, Q24 looks bad.I got a hold of Miller and the part is a Fairchild FDD3682 N-Channel MOSFET. Cheap, 10 for 10$ USD. They are on the way.Now I'll brush up on my troubleshooting skills and see if I can test the remaining MOSFETS in circuit. Also, I need to find out the recommended way of removing conformal coating before desoldering/soldering.

author: KG7AMV
author_rank: Frequent Contributor
timestamp: November 21, 2023, 04:38:09 am
content: My Experience with miller is if you call tech support and ask nicely and know know what you are doing and you have machine serial #, Board # and revision # if it is out of warranty and or production revision they will generally give schematic and bom. Miller has always supported the self/independent repair of their machines.

author: frostheave
author_rank: Contributor
timestamp: November 28, 2023, 03:11:58 am
content: Very good. I will ask again tomorrow. Thanks.

author: frostheave
author_rank: Contributor
timestamp: December 05, 2023, 04:49:33 pm
content: So, just to complete this thread. By the way, I was able to compare readings betweenthe failed board and a known good PC-1 board. That was a big help.* 350P Aluminum Welder had HELP 6 code and push pull gun motor did not turn* Replaced Q23 and Q24 on board PC-1* HELP 6 code cleared but gun motor still did not run* Replaced D5, D6, and R264 on board PC-1* Welder now works as normalQ23 and Q24 are FDD3682 MosfetsD5 and D6 are P6SMB15A-E3/52 DiodesR264 is a LRC-LR2512LF-01-R200-F Resistor

author: KG7AMV
author_rank: Frequent Contributor
timestamp: July 23, 2024, 05:21:16 pm
content: Quote from: frostheave on November 13, 2023, 06:19:41 pmMiller has been great at supporting #righttorepair providing schematics and component level information.I am Glad you were able to fix it.
miller xms 403 current sensor - Page 1
Forum section: electronics / repair

author: rodrigopires
author_rank: Regular Contributor
timestamp: March 20, 2023, 10:38:51 pm
content: I'm repairing a miller xms 403 welding machine that displays help 1 error, that is a fault in the input current sensor. I looked around and everything looked ok. Disconnected j2-1 from the board and the error disappeared, but when I connect it again the error pops up. What could be causing this?White wire is phase and black wire is sensing.

author: peb
author_rank: Newbie
timestamp: March 21, 2023, 04:00:33 am
content: It looks like your board is partially damaged (left to L1-2 clamp). Can't some copper tracks on the other side be broken?I would check the foil capacitors on the board.I have solved a problem in the past where the capacitors degraded over time and only had about half of their original capacity.The image is not sharp, probably to the right of the POS label (prime suspect..) and above R7 label.
milwaukee 0222-1 corded drill repair and part identify - Page 1
Forum section: electronics / repair

author: Pete66
author_rank: Regular Contributor
timestamp: June 28, 2021, 02:53:12 pm
content: Hello,I have an old milwaukee 0222-1 hole shooter corded AC drill.I was wondering if anyone knows what is the part circled in picture 2 and what is its purposeThe service parts document calls it a "remote electronic assembly"Is this the part that controls the variable speed?I thought the variable speed triac circuitry was built into the actual switch.Thanks

author: jpanhalt
author_rank: Super Contributor
timestamp: June 28, 2021, 03:12:07 pm
content: It agree it is part #45 (remote electronic). I suspect the "remote" part derives from it being separate from the speed control switch. It is part of the variable speed electronics.

author: bdunham7
author_rank: Super Contributor
timestamp: June 28, 2021, 03:16:02 pm
content: I'd assume it's the triac, plus some bits and bobs. You can look at the switch assembly and see what is there.The part is obsolete, but there's a seller on Amazon that appears to have a few left. I don't know how easy it would be to make your own and fit it in there.https://www.amazon.com/Remote-Electronic-Assembly-Part-Number/dp/B001R5H1BI/ref=cm_cr_arp_d_product_top?ie=UTF8
Milwaukee battery fusible link? solder repair - Page 1
Forum section: electronics / repair

author: armandine2
author_rank: Frequent Contributor
timestamp: November 04, 2024, 09:38:39 pm
content: ..this guy hasn't filled me confidence - but i guess a version of this might do the job.I will discharge the battery first.

author: wraper
author_rank: Unknown
timestamp: November 04, 2024, 09:54:15 pm
content: Don't. At least salvage fusible element from automotive fuse (or put a whole fuse if it fits), or something like that. It's a serious risk of fire/explosion. YouTube dude is a dumbass for doing it, and thrice the dumbass for showing it to others with no safety warning. Also there seems to be corrosion on PCB which needs to be fixed as it's a hazard too.

author: armandine2
author_rank: Frequent Contributor
timestamp: November 04, 2024, 10:47:47 pm
content: ..this guy may be a better guide - time to assemble the kWeld

author: jerryk
author_rank: Regular Contributor
timestamp: November 04, 2024, 11:11:54 pm
content: I just used a 60amp Maxifuse by Littlefuse and soldered it in on my Dewalt 5 AH batteries. You have to cut the blades off but in the end you do have power rating of your repair FWIW.Jerry

author: armandine2
author_rank: Frequent Contributor
timestamp: November 05, 2024, 08:45:20 pm
content: ...a fix, with some surprises.It was agreed a fuse  soldered to the existing fusible plating area was the wise move....my little/fine Metcal soldering iron was happiest with this lead free soldering task...on the charger I got four lights sooner than I imagined, after those longer two hours discharging it at 1 -2 amps...to check the battery i used my Makita impact wrench with a battery adaptor - with its torque adjustable, luckily for me I set it low to start with.
mini-MELF diode ID - Page 1
Forum section: electronics / repair

author: TheMG
author_rank: Frequent Contributor
timestamp: June 18, 2024, 01:12:14 am
content: Is there any way to accurately identify mini-MELF diodes?The ones I'm looking at look basically identical to this picture:https://www.mouser.com/images/marketingid/2021/img/173270389.png?v=070223.1037(single black band and no other markings).This is for a Tripp-Lite SU1500RTXL2UA I am trying to repair for someone. Of course, schematics are unobtainium. The diodes that have gone short form a bridge rectifier rectifying the output of a current sensing transformer. There is another current sensing transformer in the UPS also with a set of 4 identical looking diodes which aren't shorted, these measure around 0.48V forward drop with a multimeter, so I know they are not SCHOTTKY (forward voltage too high) and based on their function in the circuit they would not be zener diodes either, so most likely standard silicon diodes of some kind.However... no idea about other parameters such as reverse voltage rating or if they are standard or fast recovery time (if that even makes any difference), that type of thing. Based on this current sensing circuit's purpose in providing current feedback to the PFC boost regulator, probably safe to say we're dealing with relatively low currents.Any ideas on what a suitable replacementmightbe for these mini-MELF diodes?
Mini-USB Connector and Pads Ripped Off from PCB. What Glue to use? - Page 1
Forum section: electronics / repair

author: niconiconi
author_rank: Frequent Contributor
timestamp: November 11, 2020, 02:55:07 am
content: Simple question: I have a Mini-USB connector completely ripped off from the PCB. All four mechanical pads were gone. Which type of glue should I use to securely glue a new connector back together?

author: ataradov
author_rank: Super Contributor
timestamp: November 11, 2020, 03:20:27 am
content: Epoxy and only epoxy.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 11, 2020, 04:58:59 am
content: Cyanoacrylate and baking soda?

author: ataradov
author_rank: Super Contributor
timestamp: November 11, 2020, 05:02:50 am
content: Quote from: Alex Eisenhut on November 11, 2020, 04:58:59 amIt is mechanically pretty weak. Plus it does not really stick to the metal.
miniDSP 2x4 HD USB DAC+DSP repair. - Page 1
Forum section: electronics / repair

author: djsb
author_rank: Super Contributor
timestamp: August 18, 2024, 06:22:00 pm
content: This topic is to log my attempt to repair my miniDSP 2x4 HD USB DAC+DSP which has suddenly stopped outputting any sound. It has been turned on for a while, so maybe something in the power supply has developed a fault.https://www.minidsp.com/products/minidsp-in-a-box/minidsp-2x4-hd?gad_source=1I will first attach a few PCB photo's in order to aid orientation. There are no official schematics or other service information that I am aware of, so I have to try to fix this by doing some research and investigation on my own. I have made some initial checks on the op amp and linear regulator voltages, and they seem OK. I don't know where the negative supply for the audio op amps comes from. My next on the list for checking is the tps65261-1 switch mode regulator and all the yellow tantalum caps (close to the large aluminium SMD cap). There is Hiss from the amplifiers (I use 2 x stereo amps in an active filter setup) after a small delay startup, so the output stages (of which there are 4) appear to be OK. I will list the chips on this side of the PCB later.

author: djsb
author_rank: Super Contributor
timestamp: August 18, 2024, 06:24:53 pm
content: Here is a photo of the reverse side of the PCB. I will list the chips on this side of the PCB later.
MINILAB 603B - Page 1
Forum section: electronics / repair

author: TINY56
author_rank: Newbie
timestamp: June 28, 2023, 03:34:22 am
content: HI i have a MINILAB BWD 603B that is not working as it shouldthe function generator is not working - the unit powers up ok and output power supply 200v dc and 6.3v ac are ok but no waveforms are generatedany help would be greatly appreciated in repairing this relic

author: Shonky
author_rank: Frequent Contributor
timestamp: June 28, 2023, 03:55:03 am
content: Got schematics?http://bee.mif.pg.gda.pl/ciasteczkowypotwor/B.W.D/bwd_603b_mini-lab.pdf

author: David Aurora
author_rank: Frequent Contributor
timestamp: June 28, 2023, 05:23:24 am
content: I seem to recall these having a really good service manual, though I haven't looked at it for a million years (I've got one of these up on the shelves somewhere too).First thing to check obviously is the supply rails for that section and then work from there, the service info is very readily available.

author: TINY56
author_rank: Newbie
timestamp: June 28, 2023, 08:11:45 am
content: THANKS for that info guys - i will need to do some more research as it appears there are a number revisions for the BWD 603B and mine is an early one Issue 13 i think ??

author: Shonky
author_rank: Frequent Contributor
timestamp: June 29, 2023, 06:57:51 am
content: Issue 7 with schematics. Average of issue 23 and 7 is issue 15 so should be close yeah?https://archive.org/details/bwd-603-b-mini-lab/mode/2up

author: TINY56
author_rank: Newbie
timestamp: June 29, 2023, 08:20:13 am
content: thankyou for all the input much appreciated and it did help a bit - i think i have very early version ser # 48800 seriesi have 4 of these all with the same symptom - no wave form output so i assumed would all be the same fault - not trueC1 10u 16v tantalum capacitor short circuit on 15v+ railAM on/off switch contacts dirtymain frequency adjust pot loose and rotated till it broke 2 of the three wire connected to itall working now just have to calibratethanks again
MiniWare ES15 Electronic Screwdriver repair - Page 1
Forum section: electronics / repair

author: Bibbbi
author_rank: Newbie
timestamp: June 14, 2022, 05:00:47 am
content: Hello gentlemen,I have an ES15 Miniware electronic screwdriver that was delivered defective.As soon as I press the button, the device switches on and the message "IDChip Err" appears immediately on the display.Is there a way to fix the error?Here are some pictures:

author: Gyro
author_rank: Super Contributor
timestamp: June 14, 2022, 08:47:17 am
content: If it has been delivered defective, the sensible thing to do is contact the supplier for replacement or refund rather than messing with it. [EDIT: Alternatively try contacting miniware directly, with the photos and serial number to see if they have a resolution.]The error code seems to indicate some sort of validation error - maybe somebody is even faking these things these days (although it does look genuine), who knows these days. It doesn't sound fixable without some knowledge of the ID chip or it's contents anyway.Once you have pulled it apart, your options become limited.
Minix Z83-4 - red light - Page 1
Forum section: electronics / repair

author: shianne
author_rank: Contributor
timestamp: March 12, 2022, 09:35:13 am
content: Hello,some day ago I have received a Minix Z83-4 (Intel Atom x5 Z8350-based nettop) that should be disposed of.Reason: Only the red light lights up when a power supply is connected.Hm, this seems to be a known problem:https://theminixforum.com/index.php?threads/what-do-the-colors-of-the-led-light-stand-for.21/OK, I have no invoice and the device is out of warranty. And I am curiousSo I took the device apart and let my eyeballs do a optical inspection.Well, an attempt at heat dissipation in the past.-> U16-ausgebrannt-Beschaltung.jpgIt could be that it was too much heatAfter firing up the microburner(Ersa H25 is too weak) I can see a little bit more.But nothing what I did not know before by probing with the multimeter.-> U16-entfernt-Beschaltung.jpgLet's sketch a little bit:-> Skizze-Eingangsschaltung_LQ.jpgSo U16 seems to be a main power switch controlled by - whatever...And yes, I replaced it with a wire.But I'm interested to know: What is the idea behind U16?My first guess: It is the "main power switch" to reduce power consumption during power-off state.But if U16 opens, the red light comes up (red light = The voltage outputs by the power adapter is not right.). So this can't be the idea behind.Here a bad photo of the whole PCB top side (if someone is interested in):-> PCB-BS-Foto_k.jpgEdit: I'm too stupid to use the inline attachments, sorry. I've added the image names.

author: shianne
author_rank: Contributor
timestamp: March 12, 2022, 07:18:43 pm
content: After doing some tests today I would say: Using a bridgewire instead of U16 works fine.

author: shianne
author_rank: Contributor
timestamp: March 27, 2022, 08:06:12 am
content: A short follow-up: The Minix Neo Z83-4 is working 24/7 as datalogger since my repair. So I guess whatever let burn U16 did not damage other parts.The UEFI seems not to have an option of powering up the device after power is connected. So I built in a own circuit yesterday. First time I used 555The shown circuit may not work for short power failures because the C for time delay is not discharged quick enough.
Minolta Flash Meter V - service manual needed - Page 1
Forum section: electronics / repair

author: CosteC
author_rank: Regular Contributor
timestamp: March 20, 2023, 07:54:10 pm
content: I got Minolta Flash Meter V which does not meter anything. Digital part seems to work correctly, no obvious damage, wires to photodiode head are fine. Does anybody have any experience or service manual? I can put photos and more details here if it can help.
MIRAGE 2530G 144-148Mhz (25 in/300 out) HELP - Page 1
Forum section: electronics / repair

author: STEVE (KO4ENU)
author_rank: Newbie
timestamp: May 05, 2022, 06:18:34 pm
content: Greetings to all,I have an older MIRAGE 2530G 144-148Mhz (25 in/300 out) where the T pad input attenuator legs have broken off. I have called MFJ/Ameritron and numerous technicians that are not willing to work on the amplifier because they do not have a schematic. I am looking for a schematic or anyone that may know the value of the T pad input attenuator. THE pad is labelled with KDI in red on it.SpeculationI looked on the KDI data sheet/website and it looks like a KDI PPA20 but what is the db value.I have seen schematics online and they all omit the value. At this at this point I will also take best logical guess answers or any suggestions.Thank you in advance73SteveKO4ENU

author: m k
author_rank: Super Contributor
timestamp: May 18, 2022, 03:06:21 pm
content: Type seems to be [basic series]--[desired dB] when ordering.Maybe dB is a faint atypical place marking.
Missing enable on +5v sec pwr rail AMD Firepro D500-B/Mac Pro late 2013 - Page 1
Forum section: electronics / repair

author: EEV_TechForum_drb
author_rank: Newbie
timestamp: December 08, 2023, 02:38:57 am
content: Sub: Missing enable on +5v sec pwr rail AMD Firepro D500-B/Mac Pro late 2013Ref: 1/ MacPro6,1 Late 2013/A1481 MD878LL/A (3.5 GHz 6 Core Xeon E5-1650v2)Gfx-B: APN: 661-7548 PPN: 820-3533-A AMD FirePro D500-B 3GB Vmem2/ Figure 1 Gfx-D500-B Front Facing3/ Figure 2 +5v supply (zoom-in)Intro:While troubleshooting a Mac Pro(6,1) referenced above I discovered the +5v secondary supply did not stand up on the D500-B graphics card as a result of a missing enable signal. The +3.3v secondary rail was the only rail that did standup. I tried to perform a logic/circuit trace with power applied on the pcb but found this to be high risk do to lack of accessibility while probing and thought reaching out to the technical community for technical direction would be a better approach.Diagnostics:Instead of micro-troubleshooting I injected +3.3v dc on the enable pin through a 22k ohmResistor. The +5v supply stood up. Note that probing pin 10 for resistance resulted in 42k ohm and in diode mode 0.539v. I attempted to trace pin 10 back to its’ source and this is where I need assistance.Mahalo for your support
Agilent 54382B Infiniium Oscilloscope Dead HDD Recovery - Page 1
Forum section: electronics / repair

author: electronic_guy
author_rank: Regular Contributor
timestamp: December 25, 2023, 04:54:49 pm
content: Hi,I got an Agilent 54832B 1GHz oscilloscope without HDD detected. The equipment seems to be still not opened, warranty void sticker is still there. The CD drive and Floppy drive is present. I think this one is an old one without the VIN number. I also have a CD named as Recovery CD. But there is no floppy disk required for booting. What are the chances of recovering an equipment like this ? See the pictures.I have come across some files required for the recovery on another website(see the picture). The guide wants me to put the bootable floppy first to boot it from that and then use the recovery CD to reinstall the OS. Would this work or will I need to send it to a calibration center afterwards to get the correct calibration ? I understand that there are 4 ASICs that might be even not working on the acquisition board. I just need to know if I have all the required stuff to get started to reinstall the OS on HDD and see if I can move forward from there.Thank you.
Missing inverter components identification - Page 1
Forum section: electronics / repair

author: jerryk
author_rank: Regular Contributor
timestamp: January 14, 2024, 05:10:13 am
content: I have a Magnum MS2012 inverter that had some components removed that I'm trying to identify. I have attached some photos of an old board that I repaired that had these components intact if this helps. Problem is they are ceramic caps with no labels and part of me thinks the cap values could be critical on the charge pump IC. Just afraid of screwing it up by experimenting. Here are the datasheets for the two IC's.AD8672 (missing cap C33)and theTC7662B (missing cap C35).I attached a couple of crude partial schematics showing the caps location in the circuits.It's actually a nice little inverter that I think it's only original problem was corrosion. Then the owner dropped the cover on the main board. Hence the missing components.As always any help is appreciated.Jerry

author: fzabkar
author_rank: Super Contributor
timestamp: January 14, 2024, 08:47:02 pm
content: The application examples in the TC7662B datasheet would suggest a value of 10uF for C35.AD8672-A appears to be configured as a voltage follower. Is OUT A connected to +IN B of AD8672-B via a resistor? If so, what is the value of this resistor?

author: jerryk
author_rank: Regular Contributor
timestamp: January 14, 2024, 10:55:41 pm
content: Here is a more complete schematic of the 8672. I corrected the resistor value between OUT B and -IN BEdit: I cannot find where the input to the voltage divider that feeds +IN B. I don't know if that's needed or not. Also sorry about the crude schematics above. I screwed up Kicad on my laptop and took a moment to figure out what I did.Jerry
Missing row on HD44780U LCD screen - Page 1
Forum section: electronics / repair

author: de_light
author_rank: Regular Contributor
timestamp: May 24, 2021, 07:49:40 am
content: I have a 20x04 HD44780U LCD with the I2C backpack. It's missing a row as in the picture. Can anyone advise on troubleshooting this?

author: coromonadalix
author_rank: Super Contributor
timestamp: May 24, 2021, 08:54:41 am
content: Some of them have a zebra strip between the pcb and the lcd glass, sometimes a cleanup can solve the problem, or maybe there is not enough pressure to make a good contact ?You can use you fingers to pinch the lcd frame and the pcb to see if it goes away ?An zoomed out photo to see the whole lcd assembly would help
Mitac 5021 1995 vintage  - Page 1
Forum section: electronics / repair

author: youyou
author_rank: Newbie
timestamp: October 05, 2025, 06:44:58 pm
content: Hey guys!I recently got my hands on a Mitac 1995 5021, a real vintage gem! Unfortunately, it doesn’t power on… 😕After a bit of troubleshooting, I found out that the BIOS chip is fried. The original BIOS version is 1.07, but I just can’t seem to find a ZIP file anywhere to flash onto a new chip.Does anyone have an idea or a link where I could find this BIOS file?Thanks in advance to anyone who can help me bring this old machine back to life!
Mitsubishi E200 HMI - Page 1
Forum section: electronics / repair

author: gurar
author_rank: Newbie
timestamp: October 15, 2024, 03:17:05 pm
content: Hello,I have several Mitsubishi E200 HMI with similar problems. They power up OK and run the self-test diagnostics OK. However, they immediately show messages "Formatting Flash" and "Erasing Memory" before going to the Edit/Transfer/Setup menu. At that point, I can navigate the menus and then load and verify my project via SW-MTA-WIN and the HMI functions normally. If I quickly cycle power, it starts up normally. If I wait several seconds before powering up, I get the Formatting and Erasing messages again. I have replaced the surface-mount flash memory chips with no change and loaded BIOS 4.03 with Sysload. Any ideas why my project keeps getting erased? Thank you.

author: coromonadalix
author_rank: Super Contributor
timestamp: October 15, 2024, 03:31:58 pm
content: some talk herehttps://www.plctalk.net/threads/beijer-mitsubishi-e200-flash-error.54638/i would have said program corruption, memory corruption ... maybe the bios is going nuts, any updates with more recent ?https://www.reddit.com/r/PLC/comments/1d7hurr/hello_i_have_beijer_mitsubishi_e200_program/https://forums.mrplc.com/index.php?/topic/23676-e200-hmi/some help on plc forumsPLCS.net ....

author: gurar
author_rank: Newbie
timestamp: October 15, 2024, 03:39:11 pm
content: Thanks. That first link was also me, 14 years ago. No luck back then, and I returned the HMI I had bought on ebay. I have a little more experience now, but this is clearly a board issue. I had assumed the flash memory chip was faulty (thus requiring to be reformatted), so I got some new chips and had them installed. High hopes, but no luck again. Dunno if the RAM chip or main processor is causing this trouble, or maybe something else on the board.
Mitsubishi HS-CX6 camcorder schematics/service manual wanted - Page 1
Forum section: electronics / repair

author: MindBender
author_rank: Regular Contributor
timestamp: June 11, 2019, 07:52:57 pm
content: I am looking for the schematics or service manual of the Mitsubishi HS-CX6 vintage camcorder. Not because I am fixing one, but because I am breaking one. It has an extraordinary viewfinder, with a micro CRT and colour wheel (https://www.eevblog.com/forum/projects/smallest-colour-crt-viewfinder/).I would like to repurpose it, but it is less than straight-forward to drive... Hopefully the service manual will point me in the right direction.Who can me out to find the schematics?
Mitsubishi hts-100 red power light - Page 1
Forum section: electronics / repair

author: TrooperN
author_rank: Contributor
timestamp: September 09, 2021, 04:58:19 am
content: Hello, I have recently been having an issue with a hts-100 where after blinking orange a few times the power light turns red. I have checked for power, however I do not have a way of validating any of my measurements since I can't find a manual or schematics or something that might contain more information. If anyone knows what the issue may be or where a manual can be found, and would be willing to share, that be be greatly appreciated!

author: m3vuv
author_rank: Super Contributor
timestamp: September 09, 2021, 08:27:30 pm
content: is this a tv car or what?,we are not mind readers!!!,or should i create a post,my crystall ball needs fixing!.

author: TrooperN
author_rank: Contributor
timestamp: September 09, 2021, 11:47:16 pm
content: Google says it is a home theater system (hts) integrated amplifier.
Modern Replacment for 1980's fuse - Page 1
Forum section: electronics / repair

author: HuweyII
author_rank: Newbie
timestamp: January 14, 2024, 01:22:02 am
content: This battery pack for a 1984 HP 110 Portable has a fuse or maybe a fuseable resistor. The wiring diagram and circuit description lists it as a 0.5A fuse. So far I can't make sense of the color codes. It looks like a fusible (flameless) resistor to me, except that the color codes don't match up.This fuse was blown due to my own ham-fistedness. So I need to replace it. My gut says to just replace it with a 0.5A pico fuse. But I figured I'd ask here if anyone knows exactly what this is.Maybe replace it with something like this?https://www.amazon.com/uxcell-Axial-Leaded-Telecom-Communication/dp/B07S79DGF6/The fuse is the green resistor-looking thing on the top of the battery pack board in the attached photos

author: coromonadalix
author_rank: Super Contributor
timestamp: January 14, 2024, 02:37:43 am
content: seems to fit attached image not sure it's the good onegreen black and brown redwho would be 5 ..... exponents / divider / multiplier .... should be 50 divided by (10 exp 1) 100, will give your 0.5 amp, and the red color give a 2% tolerance ??you have to find the charts on the webnot to be confused with the resistor color codes, because the multipliers bands etc ...

author: HuweyII
author_rank: Newbie
timestamp: January 16, 2024, 06:31:18 am
content: Awesome thanks! I've never come across a table of color codes from fusible resistors. Now I know!

author: wasedadoc
author_rank: Super Contributor
timestamp: January 16, 2024, 10:44:14 am
content: Quote from: coromonadalix on January 14, 2024, 02:37:43 am5, 0, multiplied by 10^1 is 500 mA.

author: Ian.M
author_rank: Super Contributor
timestamp: January 16, 2024, 03:31:49 pm
content: Google:500mA axial pcb fuseto find ones in the same form factor to replace it.I note the battery pack uses Cyclon lead acid cells. Unless they've been replaced in the last decade or so and kept charged, they are probably dead or near dead. Fortunately they are still available. For bench testing you could hook up any small 6V SLA to the terminal board.
Modfication of CH341A programmer - Page 1
Forum section: electronics / repair

author: R-1125F
author_rank: Regular Contributor
timestamp: February 13, 2025, 02:17:39 pm
content: Is the modfication of CH341A programmer voltage for 3V chips really neccesary? I have seen opions both ways. The argument against is the the current is so low that it will not damage the chip being programmed. Any thoughts on this?

author: Gyro
author_rank: Super Contributor
timestamp: February 13, 2025, 06:56:45 pm
content: Please see the main CH341A programmer modification thread - there's plenty of information and opinion there...https://www.eevblog.com/forum/repair/ch341a-serial-memory-programmer-power-supply-fix/Edit: My opinion, the CH431A datasheet indicates that it can output 4.5V minimum at a 4mA load. It is very likely that when loaded down further by a 3V3 memory device, the CH431A will source more current than the absolute maximum ratings of the ESD protection diodes of the memory device. There's nothing to lose by doing the mod but potentially everything to gain.They were so cheap when I bought mine (black PCB version) that I bought two, keeping one for 5V devices and modding the other one for 3V3. Much easier than bodging jumpers and I have a spare, that I can revert or mod, in case I ever kill one.

author: R-1125F
author_rank: Regular Contributor
timestamp: February 13, 2025, 07:51:15 pm
content: Thanks. I was reading a W25R256JV and got some weird results. I will mod one and see if that changes.
Modification HP1663C to HP1662C, HP1661C and HP1660C - Page 1
Forum section: electronics / repair

author: GB97816
author_rank: Newbie
timestamp: July 03, 2022, 09:10:09 am
content: Hello, I bought a HP1663C logic analyzer and disassembled the device. The capacitors in the power supply have been replaced. The first traces of leaked electrolyte were already visible. I noticed that the assembly of the acquisition circuit board is very similar to the HP16550A.So I desoldered the components from an HP16550A and soldered them on the acquisition board according to the assembly of an HP1662C. With the addition of two 42R2 resistors at U21 and 31R6 for R61, this also worked fine. The device had 68 channels on it, corresponding to an HP1662C. For this I use a photo of the board of the HP1662C.In high spirits, I then also assembled the remaining components for an HP1660C. However, I do not have a photo of the acquisition card for this device. Unfortunately, that didn't work, the device reports an error in the timing circuit of the additionally installed acquisition chips. All other tests pass.The same problems also occur if only the HP1661C assembly is added. So a 64 CH update works smoothly, but something doesn't fit on 96 CH or 128 CH.Apparently it is not enough to add the assembly of the clock lines and the (probable) chip enable signals. Does anyone have high res photos of the HP1660C's acquisition board (01660-69517; 01660-66517) or of the HP1661C's acquisition board (01660-69518; 01660-66518)?Thank you for ideas and help.Greetings Georg

author: GB97816
author_rank: Newbie
timestamp: July 03, 2022, 10:56:12 am
content: Hello,a photo (from HP1661C or HP1660C) of the following areas would be helpful.
Modifying Amplifier feedback circuit - Page 1
Forum section: electronics / repair

author: reddish75
author_rank: Regular Contributor
timestamp: August 25, 2020, 03:35:58 pm
content: I have a Kenwood Ka-1000 amplifier with Sigma Drive that I'm repairing and have been told that the feedback circuit running through a switch (S6) on this amp is a weak point, same person said that the feedback circuit can be reworked to follow the best implementation of this from another amplifier with similar topology the Kenwood L-02. This is slightly above my understanding as I would also need to ensure that I have some dc for the Ka-1000's tone controls, any help, tips or pointers? Attached relevant schematics, ka-1000 first.

author: rcbuck
author_rank: Frequent Contributor
timestamp: August 25, 2020, 09:10:01 pm
content: You may get more help with this at DIY Audio Forum.https://www.diyaudio.com/forums/index.php
Moisture barrier over exposed fiberglass - Page 1
Forum section: electronics / repair

author: torquil
author_rank: Regular Contributor
timestamp: February 04, 2022, 01:26:49 pm
content: Hi!I just bought a used tube guitar amplifier, a Mesa Boogie DC-5. On the PCB in the area of one of the preamp tube sockets someone has really gone to town with the soldering iron and damaged the board. There are several places where I can see exposed fiberglass. Does this mean that there is increased risk of the board going conductive in the long run, due to moisture ingress? Also, what happens to the fiberglass if any solder flux gets in there? Would that also tend to increase the conductivity?If so, what are the recommended ways to seal up the areas with exposed fiberglass, for an amateur such as me? Can I use a bit of superglue, or should I get something tailormade for such applications? If so, what?Here is a photo of the area. A conductive board would be quite bad in this "high impedance area", where the tube grids should have a round 1MOhm to ground and there are voltage differences around 300VDC on the tube socket pins.As a bonus, they melted a lot of the wire insulation as can be seen in the photo, in addition to creating an enormous solder ball on the back of the PCB, which caused one of the tube socket pins to be shorted to ground....Best regards,Torquil Sørensen, Norway

author: Ian.M
author_rank: Super Contributor
timestamp: February 04, 2022, 01:51:52 pm
content: Clean exposed fiberglass*isn't really a problem as the epoxy resin that forms the matrix is at least as moisture resistant as the soldermask and as any coating that you are likely to be able to apply in an ordinary workshop. Don't use superglue - it isn't moisture resistant, traps contamination and produces extremely noxious fumes if heated during future repair work.However your board is heavily contaminated with flux residue and %DEITY% only knows what else. All that needs to be washed off, with appropriate solvents#, paying particular attention to any white crystalline or amorphous deposits. You don't even know if the flux used was appropriate for electronics. If acid flux was used its a time-bomb waiting to destroy the tracks and component legs by corrosion.* Assuming the exposed fiberglass isn't crushed or charred. Charred fiberglass *MUST* be removed, and if necessary the PCB structure rebuilt with glass filled epoxy. Crushed fiberglass *SHOULD* be treated the same and removed/rebuilt, but it may be expedient to clean and dry it thoroughly then consolidate it with thin superglue which wick in to even fine cracks then protect the area with lacquer or conformal coating. As mentioned earlier superglue is noxious for rework, so try to avoid soldering on the repaired area.# Commercial flux remover, or IPA as a first stage, then deionised water to remove ionic contamination, then dry IPA to remove residual water.
Molex Pin Extractor - Page 1
Forum section: electronics / repair

author: BILLPOD
author_rank: Frequent Contributor
timestamp: October 10, 2025, 01:49:53 pm
content: I've just discovered this tool that I didn't know existed, and for those that also didn't know about it,check this out:https://www.amazon.com/dp/B0C3HB1WNK/ref=syn_sd_offsite_desktop_50?ie=UTF8&aref=Acn41ZO0T2&sp_csd=d2lkZ2V0TmFtZT1zZF9vZmZzaXRlX2Rlc2t0b3A&tag=dradisplay-20&th=1Not cheap, but not too bad; and if it gets me out of a bind, it's worth it, (which is the theory I consider when purchasing ANY tool).

author: tooki
author_rank: Super Contributor
timestamp: October 10, 2025, 02:10:18 pm
content: That’s a super fancy version. You can also get whole sets of pin extractors for cheap:https://www.amazon.com/s?k=pin+extractor+tool+kitMolex’s own extraction tools look barebones and overpriced, but are well made and durable — and have instructions!P.S. When pasting Amazon product URLs, you can delete all the crap after the last slash, which is nothing but tracking stuff.

author: shabaz
author_rank: Frequent Contributor
timestamp: October 10, 2025, 02:22:46 pm
content: Not suggesting it's a good use of time, (might be though, if there's a machine shop nearby and if the tool is really needed asap) then the dimensions of the Molex tool are attached to DIY it.

author: coromonadalix
author_rank: Super Contributor
timestamp: October 10, 2025, 02:37:06 pm
content: i would say be warry of cheap china knock offs, they don't last and bend easily on some ...sure the right one is expensive but it will last, and not damage the pins retainersdon't know for the ones from amazon they seems relatively new, have interchangeable heads witch is a must ... maybe well hear some feedback's ...
Monitor Backlight repair - Advice needed - Page 1
Forum section: electronics / repair

author: kumitsu
author_rank: Newbie
timestamp: April 30, 2025, 01:06:51 pm
content: Hello. I have Dell P2722H, which have failing backlight. Sometimes left side isn't working sometimes right one. I believe it's the backlight driver that is defective but I cannot find it online. Marking are hard to read CT001CN AIN4623 2126AI. Can you help me find a replacement? thanks