hybridfree/eevblog-posts huggingface dataset:
Repair brymen 786 - Page 1
Forum section: electronics / repair

author: ss78
author_rank: Newbie
timestamp: February 10, 2022, 01:24:50 pm
content: Hi folksI have a dead bm786.Inserted new fresh batteries, rotate the switch, unfortunately no display..Could anybody with knowledge guide where to start probing/ troubleshooting ?Background : I m familiar with simple circuit, have another working fluke multimeterGreatly appreciate it.

author: ss78
author_rank: Newbie
timestamp: February 14, 2022, 01:29:32 am
content: Preliminary probing.Output from linear regulator is normal about 3.5vThere is 3.5v into ic which I believe is a microcontroller.No short found on any caps ...

author: Antrus
author_rank: Contributor
timestamp: October 26, 2023, 08:20:01 am
content: hello, can you share eeprom 24cs04? It's on a board with buttons.
Repair CH1 - Rigol DG1022 - Page 1
Forum section: electronics / repair

author: Giovanni28
author_rank: Contributor
timestamp: April 12, 2021, 10:39:28 pm
content: Hi!Please, can someone help me identify the fuse that most likely is no longer making channel CH1 of my function generator? How many amps?->Utility->Test don't report errors.
Repair chinese multimeter - Holdpeak HP890CN - Page 1
Forum section: electronics / repair

author: palazziandrea@yahoo.it
author_rank: Newbie
timestamp: February 12, 2022, 04:05:18 pm
content: Hi,I've brought this cheap chinese multimeter - an Holdpeak HP890CN - but soon after it stopped working properly: basically it will only measures volts, while when measuring millivolts it starts from zero and then slowly rises. On all the other modes it measures zero.On a visual inspection of the board I couldn't see any component that have obviously failed, everything seems ok to my newbie eye.The multimeter is based on the DTM0660 (translated datasheet herehttps://www.improwis.com/projects/reveng_multimeters/chips/dtm0660-brochure.pdfDoes anyone have some ideas or some troubleshooting suggestions to try and fix this?ThanksAndrea

author: Kleinstein
author_rank: Super Contributor
timestamp: February 12, 2022, 04:34:56 pm
content: Assuming the DMM uses the typical application circuit shown in the data-sheet, the first parts to check are the 2 transistors used for protection (may be short) and the PTC and possible extra resistor in series with it (may be open). A bad contact at the range switch is also possible - though usually more like a problem after longer use.The fuses may be a problem for the current ranges.

author: palazziandrea@yahoo.it
author_rank: Newbie
timestamp: February 13, 2022, 06:13:14 pm
content: Hi,Thank for your answer, if I correctly identified the transistors it seems in fact that they are shorted: I have a short circuit when I test the pins highlighted in the picture below.The PTC seems ok.So, next question: should I trust the typical schematics and get two 8050 or should I look for something else? There's a Y1 mark on the component, but I couldn't find anything specific when googling it...ByeAndrea

author: picburner
author_rank: Frequent Contributor
timestamp: February 13, 2022, 07:15:32 pm
content: If you look carefully at the schematic in the pdf you posted, the two transistors T3 and T2 (Q1 and Q2 in the schematic) have the base and the collector short-circuited. So it is normal that you have measured a short circuit where you have highlighted, they are just the base and the collector.The Y1 smd code corresponds to a SS8050 transistor.
Repair Chinese Power Supply MCH-305D - Page 1
Forum section: electronics / repair

author: mava70
author_rank: Newbie
timestamp: February 18, 2021, 10:32:09 pm
content: Hello,I need an help for repairing MCH-K305D:I did a bad modification of the power supply that blows out one of the Mosfet 10N60C I put a too bigger resistor in series to the Gate and the part shorts out in all pins. After swapping the part, I power on the PS and all seems good with current knob all way down, but after turning it a little up I got another short and the Mosfte blows out again. The Fuse never blows out.For these test I have a 60W bulb in series to the power supply to limit current of any short I got, but also first short without the bulb doesn't blow out the fuse but main power house switch cut down.I removed the Mosfet and I try to do some kind of measurement, without the mosfet I can power on the PS without any problems, led lcd's show's all 000 but seems working, I start doing measurement in the low power section and I don't find any fault 12V is present, U1 OPA vary from 0 to 5V when Voltage knobs turn up and down, I have a similar 0-2.4 going up and down at pin 1 of U4.On pin 11 and pin 14 of U4 (SG3525) on the oscilloscope there is a pulse and the same pulse reflect after the chopper trasformer T2 D15 at the gate of the broken Mosfet Q22 si similarly present.300V is present as well on Source of Q22, well rectified by the bridge.I don't see any modification on the pulse out of U4 by turning up and down the voltage knob. Is this normal? I have the same pulse same frequency and same amplitude, measured after T2 in around 12V.I suspect some problem after the mosfet what do you think? What worth checking more?schematic is hereThanksMarco

author: tautech
author_rank: Super Contributor
timestamp: February 19, 2021, 09:38:48 am
content: Oh dear, you learnt not to change gate resistors didn't you.As I see it the current sense on B1 may not be working correctly. Sensing is done at B2 and fed back to U4 pin 8.Full schematics are in this post:https://www.eevblog.com/forum/testgear/cheap-variable-switching-power-supply/msg1240531/#msg1240531

author: mava70
author_rank: Newbie
timestamp: February 19, 2021, 07:01:53 pm
content: Quote from: tautech on February 19, 2021, 09:38:48 amSure!! But how to learn repairing whitout destroing something?= Thanks

author: mava70
author_rank: Newbie
timestamp: February 20, 2021, 11:32:51 am
content: Then, probabily I find the problem, swapped both mosfet that is bot shorted, checheck component around and seems working, powered on and tadaaa, I'ts working, I put on a small load and with 80 mA of load at 18V everything seems fine, I measure only an hight temperature in RT1 (50-70 degree Celsius) is this normal? Oscilloscope give me a ripple (chopping noise) of around 100mV pp, normal?

author: tautech
author_rank: Super Contributor
timestamp: February 20, 2021, 08:04:57 pm
content: Quote from: mava70 on February 20, 2021, 11:32:51 amYes, NTC thermistors need to run hot.QuoteYes normal, these are not very quiet PSU's so for sensitive circuits you need add additional capacitors to lessen the HF ripple.Good fix, well done.
Repair COB (blob) electronics - Page 1
Forum section: electronics / repair

author: prampec
author_rank: Newbie
timestamp: August 19, 2023, 09:09:52 pm
content: Hello,I have some faulty calculators I would like to fix, but there are way too few components in them. Just a COB and 3 passives. First of all, what could go wrong in these circuits (not mentioning the visible problems)? E.g. COB can fail? Is there a method to fix it?Thanks,Balazs

author: schmitt trigger
author_rank: Super Contributor
timestamp: August 19, 2023, 09:32:36 pm
content: I could be wrong, but those hard epoxy blobs cannot be removed without damaging the silicon chip itself.But, let’s assume you can remove safely all the epoxy without cracking the chip itself or pulling the bonding wires… What comes next? Do you know the chip’s part number? Do you have the means to detach and re-attach the bonding wires?

author: Haenk
author_rank: Super Contributor
timestamp: August 20, 2023, 03:09:30 pm
content: unfixable, sorryas mentioned, the blob is not removable, also it encloses the die and bonding wires - thermal attack will destroy the pcb, chemical attack will destroy the pcb, physical attack will likely destroy the die and certainly the bonding wiresHowever COB calculators are usually not very rare, so just buying another one is probably cheaper than working time anyway.Btw. the first to use COB is likely the Novus 650. Which was really built to budget.

author: prampec
author_rank: Newbie
timestamp: August 21, 2023, 07:56:41 am
content: Thanks for the answers.COB is not fixable, I was expecting that. But does your answer means, that in these cases the COB failed? It is quite hard for me to believe a blob covered silicon chip can go wrong.E.g. does it contains some EEPROM that can be reprogrammed? (In theory, because nobody has a firmware for that, that's for sure.)

author: Haenk
author_rank: Super Contributor
timestamp: August 21, 2023, 08:46:58 am
content: It's probably not too hard to reverse voltage in a calculator (switching battery direction or wrong polarity/voltage of external PSU), and COB always means "lowest costs possible", i.e. not a lot of protection, if any at all.Usually, these CPUs are mass-produced with masked ROM, so no EEPROM.If the CPU is broken, the unit is done.However there sometimes are a protection diode and a small electrolytic cap for voltage stabilization - these can fail and could be replaced.

author: CaptDon
author_rank: Super Contributor
timestamp: August 21, 2023, 01:58:40 pm
content: Could be some of the tiny electrolytic or tantalum capacitors are bad? I recently fixed an electronic 'Master Mind' game that was built very similar to a vacuum flourescent display calculator by replacing EVERY capacitor. Even the mylars were bad!! Probably really poor quality to begin with. Also, some of the soldering was suspect with years of mechanical shock. Some of the Sorenson power supplies with digital panel meters using the black blob technology were not repairable. The meters drifted and had no way to be zeroed. We just used analog meters as replacements.
Provide reference for newbies like me to fix DS1742W - Page 1
Forum section: electronics / repair

author: lern01
author_rank: Regular Contributor
timestamp: December 16, 2023, 09:33:12 am
content: There are two purposes for posting this post today. One is to thank netizen Jarek for his patient help; the other is to show newbies like me how to repair DS1742W.1. Disassembling DS1742W is a careful job. It will be easier to remove it with a desoldering device (especially a vacuum desoldering device), but you still have to be careful because the circuit is too thin.2. How to break open DS1742W. There are many posts on the Internet for reference. But there is a trick. First use a carving knife to remove the plastic in the area that needs to be dug out (using a magnet to determine the location of the battery is a good way), and then use a soldering iron to heat the epoxy resin to soften it, so that it can be easily removed.3. The 1625 battery I used (the actual size is 1225), the positive and negative electrodes are welded with nickel sheets using a spot welder for easy welding, and then short wires are used to connect the positive and negative plates. Note that the positive terminal is at the bottom and the negative terminal is at the top.4. Programming. This process confused me for a few days. I am very grateful to Jarek for his help. With his help, I moved towards success step by step. Please note that what confuses me and what people may not care about is that because this oscilloscope is old, substances are easy to attach to the pins. I use TL866CS and I can't program it. Jarek also provided many methods. I had no choice but to use a microscope and found that there was a thin layer of substance attached to the two pins. I cleaned it with detergent and then programmed it successfully. Attached picture:Note: Select IC: DS1220 (R/W) in the programming software and close Verify after. According to the introduction of DS1742W, it can withstand voltages below +6V for a short period of time.

author: button.ch
author_rank: Contributor
timestamp: December 06, 2024, 08:08:00 am
content: After verification, TL866 can be modified by disconnecting a resistor or adding a switch to increase its voltage to around 3.6V
Repair end of VGA connector cable (to speaker box) - Page 1
Forum section: electronics / repair

author: Demosthenes
author_rank: Newbie
timestamp: June 10, 2019, 10:38:25 pm
content: I have a speaker box - Logitech Z-5500 that still works very well except for the 'proprietary' VGA cable connector hard-wired in to the controller box that plugs in to the amp. I opened the controller box and it is soldered on. There is no way I can ever replace it from that end.So it makes an almighty thumping racket as the cable moves around even incredibly slightly on the amp end - like a broken wire on something. I am hoping it is just the cable and not the amp port (because then I may as well give it to an electronics shop for parts or something).Is it possible to chop the end off a hard-wired VGA cable and splice on a new end? I have looked around for replacement speakers and honestly, offerings today are pretty uninspiring for under $1000. The 'later' Logitech model seems like a step back if anything.The system still works fine, I am hoping I can just replace the cable. For now it's on hair trigger, if I don't breathe near the cable it seems relatively stable with minimal thumping. And I really don't want to spend money on a new speaker system just because these Logitech idiots decided a proprietary hard-wired soldered-in VGA cable that is impossible to replace was a good idea.Any suggestions welcome. Thanks..Some further info about the system for a different problem in this threadhttps://www.eevblog.com/forum/repair/help-repairing-my-logitech-z-5500s/msg1172971/#msg1172971

author: Bratster
author_rank: Frequent Contributor
timestamp: June 11, 2019, 09:08:50 am
content: You won't be able to use any standard VGA cable, the way that Logitech is using it Will not be compatible with a standard VGA pinout.But you can get just that connector, it's a high density DB 15.So you would cut the connector off of your cable leaving a few inches And test out what color wire goes to what pin. And then solder the wires to the new connector.somebody may have also already figured out the pin out and color code and posted that online somewhere.and they also sell terminal block breakouts for those connectors so you wouldn't even have to solder if that's an issue for you.Edit: you need to double check this is the correct gender, but this is a breakout I was talking abouthttps://www.amazon.com/dp/B07F9S61QT/ref=cm_sw_r_cp_apa_i_sb3.CbG3AHQAZSent from my Pixel 2 XL using Tapatalk

author: Demosthenes
author_rank: Newbie
timestamp: June 13, 2019, 10:23:25 am
content: Thanks... Someone seems to have found a pin-out herehttps://www.eevblog.com/forum/repair/help-repairing-my-logitech-z-5500s/msg1173017/#msg1173017A breakout box would be awesome. It's soldered in to the control box, there's no replacing the cable.
Repair; Flir i60 Thermal Handheld . - Page 1
Forum section: electronics / repair

author: Tectek
author_rank: Newbie
timestamp: February 16, 2023, 03:54:03 pm
content: I'm taking a look at this Flir i60, a little history on it " Always handled with kit gloves and never exposed to any hash conditions "it just stopped powering up one day". After getting it to power up and getting a splash screen the screen goes blank (white screen ) , I initially felt it would be a software issue and updating the firmware might resolve it , So I did that and the device rejected the updates, Errors are, ( Combined firmware ( 2.19.1 ) is intended for Flir Ixx-series ) , ( rls ,version.kits.appkit .ver, Command Failed , The handle is invalid <aborts...>). This happens with sd card update method , after that failed i considered maybe trying to connect through the serial port i could establish communication and check I/O signals sad to say I don't have a serial port cable for this device and couldn't find one online ( I considered making one ). Teardown !!!. So after breaking the usb input by dropping it, What a dope ! It slipped out of my hand and I believe that's when it happened the Bluetooth dongle was inside and it was not on , It was the plastic insert of the usb connector that had come apart , I decided to open it up check it and make repairs that's when I discover a chip that looks suspect PS54350 , I would really like to bring it back to life any help would be greatly appreciated . Thanks
repair fluctuating DMM VC860 - Page 1
Forum section: electronics / repair

author: rve
author_rank: Newbie
timestamp: August 26, 2021, 05:03:00 pm
content: Hi,I have an old DMM (voltcraft VC860) which fluctuates a lot when measuring voltages. For example, I connected 7.4 volts DC to it (which is stable, I've checked it with a scope and another DMM) but the readout on the VC860 keeps fluctuating between 7.413 and 7.458. The last 2 digits keep changing and never settle. The value keeps increasing and at some point it starts decreasing. This repeats itself over and over making the DMM pretty useless.I've attached the schematic. If I short the input the DMM displays 0.0000 and does not change. The fluctuating happens in all voltage ranges.Measuring resistors seems to work fine. Although the resistor value on the display keeps increasing over time at a much slower rate compared to voltage measurement. But I think this could also be normal thermal influences.What could be wrong? Is this a somewhat common failure mode of DMMs?Thanks.

author: Labrat101
author_rank: Unknown
timestamp: August 27, 2021, 07:45:07 pm
content: Did you check the board for dry joints . or tin whiskers as this meter probably has been in service for many years . As you mentioned that it does zero when the inputs are shorted .So the last 2 digits floating are caused by noise .I would be inclined to clean the entire board with IPA and a soft brush . Even a hair line crackin the pcb, as it may have well have been dropped some time in its 15+ years .The very last digit may well float between 3 and 5 . but the other digits should hold reasonably stable.

author: rve
author_rank: Newbie
timestamp: August 28, 2021, 01:29:25 pm
content: Good idea, I'll check all joints. Thanks.

author: Labrat101
author_rank: Unknown
timestamp: August 28, 2021, 03:59:06 pm
content: Don't forget the rotary switch or any moving parts first as they always get abused . I don't think you have any major problems as it works. In ohms etc and noisy voltages.

author: The Soulman
author_rank: Super Contributor
timestamp: August 28, 2021, 05:08:41 pm
content: Likely a bad adjustment pot, VR 2 sets the reference voltage, maybe give that a little wiggle and see if that changes things.Note the position before you touch it, you need to return it to the same position after wiggling,otherwise your voltage readings will be incorrect.

author: rve
author_rank: Newbie
timestamp: October 27, 2021, 10:22:16 am
content: Hi,I finally found the issue. I've cleaned everything and I found that at least one contact on the rotary switch was misplaced. After putting all contacts in the correct position it works again.Thanks for the suggestions!

author: Labrat101
author_rank: Unknown
timestamp: October 27, 2021, 12:27:31 pm
content: Quote from: rve on October 27, 2021, 10:22:16 amGlade you found the bad connection .
Repair Fluke 189 LCD. - Page 1
Forum section: electronics / repair

author: RxnWrecker
author_rank: Newbie
timestamp: June 03, 2020, 02:56:20 pm
content: I have a Fluke 189 with a cracked LCD. The LCD still functions over a portion, but the top right corner where the damage occured does not display (see photo). I assume this is irreparable and must be replaced but maybe I'm wrong? If so, I appreciate advice from whatever wizard knows how to do something like that.Odds are though I will need to replace the screen. I have searched unsuccessfully for a replacement part. The Fluke manual doesn't give me a part #, but I saw a similar post on this forum with 688181 listed as the part #, so I believe that is it. I could use help finding it, if anyone has advice, or if anyone is selling it looks like I'm buying. Also, I have little experience with LCDs, is there any cross compatibility among LCDs ie can I possibly find a screen made for something else but with similar specs and use it?Thank you, hope someone out there can help.PS I tried calling Fluke to get the part, but they haven't been any help as the part is obsolete. I'm pretty sure that the part # is correct then, but the 2 guys on the phone seemed to know even less than I do on the topic.Photo of LCD:http://autoforums.carjunky.com/photos/pic/533pA4lm/1620.jpg

author: rvalente
author_rank: Frequent Contributor
timestamp: June 03, 2020, 03:12:12 pm
content: Well, I'm very sorry to see a nice fluke in this situation...However, the 189 seems to be a a platform shared with 87IV, 89 IV AND 187 sow these could be donor parts if you happen to find a blow unit.I've found some with help of google around 40usd, please check:https://www.ebay.com/itm/FLUKE-LCD-Display-Fluke-87-IV-89-IV-187-189-/193313123423https://electronictest.equipment/collections/fluke-parts-new-fluke-lcd-displays-6/products/fluke-189-lcd-display-1https://articulo.mercadolibre.com.mx/MLM-778960530-lcd-fluke-189-_JM#position=1&type=item&tracking_id=fd2f052f-0d47-47fe-9681-7d41f2641024I may check in Braziliam repair center for you, but they always ask for unit serial so I would need it.

author: RxnWrecker
author_rank: Newbie
timestamp: June 03, 2020, 03:20:31 pm
content: Is the unit serial number written on the back under the barcode? If so its 94060200. Thanks for the links I am checking them out staring now.

author: coromonadalix
author_rank: Super Contributor
timestamp: June 03, 2020, 04:40:00 pm
content: on ebayhttps://www.ebay.com/itm/FLUKE-LCD-89-4-89-IV-187-189-Original-LCD-Display-OEM-from-Fluke/252201243742?you see some markings on the top lcd

author: RxnWrecker
author_rank: Newbie
timestamp: June 03, 2020, 07:36:23 pm
content: Thank you everyone for the replies, I am going to try and buy it and see if it works, I'll post a pic once it's all shiny and new.
Repair / Fluke 289 Error E4 - Page 1
Forum section: electronics / repair

author: azemati
author_rank: Contributor
timestamp: January 29, 2023, 10:55:50 am
content: Greetings to all friendsI have a handheld multi meter fluke 289Which unfortunately has been giving error E4 for some timeNow has anyone encountered this problem?If you have a solution let me know so I can fix it.

author: bidrohini
author_rank: Regular Contributor
timestamp: January 30, 2023, 01:31:53 am
content: Have you checked page number 56 of this user manual? There appears to be a discussion about the error messages:https://www.google.com/url?https://assets.fluke.com/manuals/287_289_umeng0100.pdf

author: coromonadalix
author_rank: Super Contributor
timestamp: January 30, 2023, 02:05:35 am
content: On other fluke meterThe error 4 is an ADC error (Analog to Digital Converter). This is caused when the ADC is not converting or producing a usable signal to the controller. The ADC chip has gone bad.Not sure it aplies to this one ?

author: azemati
author_rank: Contributor
timestamp: January 30, 2023, 08:06:05 am
content: Thank you for your replyI checked it but nothing was written about error E4

author: Ugur
author_rank: Regular Contributor
timestamp: February 02, 2023, 05:58:01 am
content: Can you share a picture of the error?

author: coromonadalix
author_rank: Super Contributor
timestamp: February 02, 2023, 11:46:45 am
content: And the obvious question : have you contacted fluke ??

author: azemati
author_rank: Contributor
timestamp: February 06, 2023, 07:35:55 am
content: Not yet
Repair FLUKE PM3380B - Page 1
Forum section: electronics / repair

author: Lascae Bogdan
author_rank: Newbie
timestamp: March 06, 2021, 07:05:47 am
content: Hello Guys ,I'm new on this forum ...I have one problem with this osciloscop Fluke PM3380B , on Digital the trace locks ok but on Analog mode is strange,I attached 2 pictures (one digital mode and one Analog mode) maybe you have some ideea.https://imagizer.imageshack.com/img923/2816/o79Ayv.jpghttps://imagizer.imageshack.com/img924/6990/5sR42k.jpgThank you very much!

author: grumpydoc
author_rank: Super Contributor
timestamp: March 06, 2021, 09:41:10 pm
content: You are seeing the flyback.Get the manual (search online, several copies) and go through the manual calibration procedure - which, amongst other stuff, sets the beam dark current. You'll probably find it's OK after that.

author: TimFox
author_rank: Super Contributor
timestamp: March 06, 2021, 10:14:02 pm
content: A more common name for that is "retrace", where "retrace blanking" may be found in the manual. "Flyback" usually refers to a power-supply technology, although traditional TV sets generated the CRT high-voltage during the retrace period and that was called "flyback". Just a suggestion to guide searching for the topic.

author: Lascae Bogdan
author_rank: Newbie
timestamp: March 07, 2021, 06:49:37 am
content: Ok , thank you for your recomendation , I will chek this and I will come back with an answer

author: HighVoltage
author_rank: Super Contributor
timestamp: March 07, 2021, 08:51:48 am
content: yes, this is a setting in the calibration and maintenance procedure and a very simple correction, if everything else is alight.I never had this problem isolated by itself.Maybe someone played with the calibration settings?To access the maintenance screen, you need to enter the password: "32415"After you are happy with the setting, you need to confirm your changes with a push of a small tool though the pin-hole in the front panel.(Behind the calibration seal)Let us know, if you fixed it

author: Lascae Bogdan
author_rank: Newbie
timestamp: March 07, 2021, 10:20:24 am
content: I made those calibration settings ,I pressed the pin-hole but it doesn't store anything, when I pressed the pin-hole on the screen I see 6 empty calibration ,soo the memory is okalso when I start the osciloscop , on the screen i see two error , battery back-up missing and time is not valid

author: HighVoltage
author_rank: Super Contributor
timestamp: March 07, 2021, 11:00:55 am
content: Did you check the two AA batteries in the back?
Repair GE Super Radio 1 - Page 1
Forum section: electronics / repair

author: marnav1
author_rank: Contributor
timestamp: June 18, 2025, 03:24:57 am
content: Hello all. Recent purchase, radio works but needs a couple repairs. The whip antenna needs replaced. The issue is the screw to remove the telescoping part of it is stripped out. Came that way, absolutely nothing to grab onto. Anyone have a novel idea how to remove it please share. I'm pretty sure I can find the telescoping part on Ebay.

author: Poroit
author_rank: Frequent Contributor
timestamp: June 18, 2025, 04:51:46 am
content: What size is the screw?https://suttontools.com/product/screw-extractors-drills-easy-out/

author: marnav1
author_rank: Contributor
timestamp: June 18, 2025, 06:07:21 am
content: Small but I dont know for sure.

author: coromonadalix
author_rank: Super Contributor
timestamp: June 18, 2025, 07:17:29 am
content: must be around m3 ... can you post a picture ?while selecting number bits ... not std one you may or could drill in the screw and slowly remove what's left of the screw

author: marnav1
author_rank: Contributor
timestamp: June 18, 2025, 07:32:26 am
content: Sure I'll post a pic later today.

author: watchmaker
author_rank: Unknown
timestamp: June 18, 2025, 11:36:01 am
content: I am presuming the stripped screw is the screw that holds the antenna to a mounting plate on the radio.If this is so, use a new razor blade to work under the screw head. Hold it against the screw's body while levering the head up and unscrew as normal. Otherwise, drill off the head using a drill smaller than the head. If you have to, glue the head to keep it from rotating with the drill (slow speed BTW). Just like drilling off a rivet head.
Repair genuine Imax B6 mini V2 - Page 1
Forum section: electronics / repair

author: dvd4me
author_rank: Regular Contributor
timestamp: December 29, 2022, 05:46:42 am
content: Hello,This is a short story of repairing the original Imax B6 mini v2. I had burned the main chip megawin because I touched the balancing leads with the soldering iron while it was connected to the PC.The ground loop fried the MCU, a burned scar was on it. Found one replacement on Ebay and change-it.There was no apparent other fail and I managed to install the original FW 1.13 using just the usb.The problem is that it stays stuck on the boot logo.After many other attempts to find the issue, I found a Turnigy 80W fw on some site that when loaded, actually it passed over the boot logo.Then I could test using ChargeMaster each cell voltages and it seems the balancing connector measures well all the 6 cells.The problem comes when I try to charge or discharge any pack.It gives a "main terminal connection check" sort of thing.After some more digging, there is a voltage check directly on the battery terminal, and because there is no calibration data it's way off.I discover this using a variable power supply that around 15V it switches from each cell measurement to Main voltage masurement.The 2 values were way off, there is something off in the calibration.I managed to bring the Main voltage down ( it goes directly to the MegaWin chip) in such way to almost match the balance leads measurement and it works with Turnigy FW, it's charging with no error.This means the SkyRC FW and Turnigy FW is not containing the calibration values and other defaults.The original Imax B6 FW must have some sort of boot checks and therefore it stops right in the beginning.I also cannot enter any calibration menu on that Turnigy FW, it seems disabled, so I cannot save any legit calibration data in the megawin MCU.Does someone know to program some calibration data just using the FW?Or how to modify the original 1.13 B6 mini FW to skip the initial boot checks and boot up?If booted, then I can start the calibration menu and write legit values.

author: fqahmad66
author_rank: Regular Contributor
timestamp: January 24, 2023, 05:26:04 pm
content: Try this...

author: dvd4me
author_rank: Regular Contributor
timestamp: January 25, 2023, 02:07:30 am
content: Quote from: fqahmad66 on January 24, 2023, 05:26:04 pmThanks for your post but Cheli does not support Megawin chip yet.I will wait for some other compatible Imax fw to come out, maybe one will boot up ( like the 80w Turnigy does) and have also calibration enabled.
Repair genuine skyrc IMAX b6 AC V2 - Page 1
Forum section: electronics / repair

author: nnannos
author_rank: Contributor
timestamp: July 16, 2020, 12:54:28 pm
content: Hi, i have the SkyRC imaxB6AC V2 and due to faulty usb cable had blew it off.But I managed to replace the TD1534, the 78M05 the mcu MA84G564AD48 and LCD Screen.I also managed to connect it with USB and by connecting GND to SDA signal and reseting it put the firmware upgrade Β6ACV2_V1.13After that the charger boots but stays at first logo screen which says SKYRC IMAX-B6AC and nothing happens, no beep no battery menu.Nothing else in circuit is at fault, can you please tell me why not working?Do i need other firmware to install or mcu needs more info to load???I bought the MA84G564AD48 on ebay and i have tested 2 chips with same result.Thank you in advance

author: dvd4me
author_rank: Regular Contributor
timestamp: December 29, 2022, 05:57:06 am
content: Hello,I just figured out why it's stuck, it's missing the calibration or some data in the boot sequence.It runs with the Turnigy 80W fw (1.13 Skyrc modified clone) but I cannot enter the calibration.See my post for more details.https://www.eevblog.com/forum/repair/repair-genuine-imax-b6-mini-v2/Regards
Repair gtx 980 ti with burnt mosfet - Page 1
Forum section: electronics / repair

author: DarielFer20
author_rank: Newbie
timestamp: June 13, 2025, 03:33:23 pm
content: I have this graphic which is burned one of the pair of mosfet that carries the output of the auxiliary power supply of the gpu, this mosfet is a EMB20P03V and as I could not find original replacement, I plan to change it for a more common commercially as the AO4407. My main doubt is if this mosfet could be compatible with the original one, since they handle approximately the same characteristics but the AO4407 handles 12A and the original 18A approximately, but considering the 8-pin auxiliary power supply is capable of delivering 150W, it would be 12.5A in that line, but these mosfet seem to be connected in parallel which would divide the amperage in 2? Anyway the auxiliary power supply would not receive the 150W because it receives 75W through the PCIe port and the rest through the auxiliary power supply, and the nominal consumption of the graphic is 250W. It should be noted that I did not detect any short on the board, I made measurements of resistance and continuity and nothing seems out of the ordinary, also this board is not mine so I do not know the use that will have given its previous owner. Thank you very much in advance for reading and any comments or corrections will help me to improve my repair, which is a hobby that I like. In summary to make everything clearer my questions would be: -Would that replacement mosfet work for me? -Should I replace both mosfets with the same model? -And should I replace the mosfet of the other auxiliary power supply as well? And forgive me but I had to use a translator D:

author: wraper
author_rank: Unknown
timestamp: June 13, 2025, 03:39:12 pm
content: Current/power ratings are pretty much irrelevant. What you actually need is that RDS(on)is not worse than original and that gate charge is the same or a bit lower. Also I have no idea how are you going to fit SO-8 package of AO4407 instead of EDFN 3 x 3.

author: DarielFer20
author_rank: Newbie
timestamp: June 13, 2025, 03:44:03 pm
content: And would I need to change the mosfet on the side? or change the mosfets of the other auxiliary power supply?
Repair HAMEG HMS1000   R&S HMS X - Page 1
Forum section: electronics / repair

author: PA3BBV
author_rank: Contributor
timestamp: January 23, 2024, 08:18:02 am
content: Goodmorning,Yesterday I switched on my HAMEG HMS1000 spectrumanalyzer and it stays completely dead. No leds are burning, no display, nothing at all.First I have checked the two fuses on the back, the are oke, then I have opened de analyzer and did a visual inspection. Nothing to see, no burned components all looks oke. I Measured the powerlead resistance and it raised in a minute to about 800k. I asume that there is a failure in the powersupply. Where do I start to look?Without a diagram troubleshouting is nearly impossible.So I have some questions:Does anyone have experience with this kind of problem with the Hameg HMS1000 or de R&S HMS-X?Does anyone have a servicemanual or at least a diagram available?Does anyony have an advice available?Cheers Leo

author: Greybeard
author_rank: Frequent Contributor
timestamp: January 23, 2024, 09:23:02 am
content: "I Measured the powerlead resistance and it raised in a minute to about 800k."Have you tried another power cord?

author: PA3BBV
author_rank: Contributor
timestamp: January 23, 2024, 11:53:43 am
content: Yes I did tried several powercords, I finaly measured that 220 Volt is arriving at the powerboard.
Repair Hameg HM1004-2 - Page 1
Forum section: electronics / repair

author: jbnl
author_rank: Contributor
timestamp: May 01, 2016, 12:25:59 pm
content: Goodday All,I have here a Hameg scoop HM1004-2 wich was working fine, suddenly the time/base went running automatic to lowest value and keeps on lowest value.Also it is not possible to change anything with the rotary's on the front or change from dc/ac.But the strange thing is that when i turn on the scoop i get no keyboard error and no mainboard error.I can switch to component tester and back, but in scoop mode i can't change anything.I have checked all the voltage's on the mainboard/psu/front board and all are correct and within spec's.Has anybody had this before or maybe a idea where this can come from ?

author: tautech
author_rank: Super Contributor
timestamp: May 01, 2016, 12:31:19 pm
content: Welcome to the forum.Sounds like a timebase problem, there's many here that can help, what service tools and instruments do you have to complete this repair?Please also provide a link to the Service manual you will use so that we are all on the same page.

author: jbnl
author_rank: Contributor
timestamp: May 01, 2016, 12:49:55 pm
content: I have received the service manual from the tech department from Hameg Germany.Where can i drop it ?I hope indeed that i will repair it because i like the scoop very much.I have a second scoop/function generator/multimeter on my workbench.

author: tautech
author_rank: Super Contributor
timestamp: May 01, 2016, 09:04:55 pm
content: Quote from: jbnl on May 01, 2016, 12:49:55 pmAny of the manual repositories in this thread are good:https://www.eevblog.com/forum/repair/repair-documents-and-links-sticky-me-please-mods/My favourites:http://www.ko4bb.com/manuals/http://www.ebaman.com/index.php/remository

author: nctnico
author_rank: Super Contributor
timestamp: May 01, 2016, 09:07:59 pm
content: I'd check the contacts of the rotary encoder and look at the signals. If the timebase goes to one setting it means there is a contact issue somewhere. Maybe it is just a matter of reseating the cables. Start with the simple things and don't assume the worst.

author: jbnl
author_rank: Contributor
timestamp: May 02, 2016, 05:19:29 am
content: Goodday,I have check the signals from the rotary and even exchanged the rotary encoder with a other rotary encoder but does not solve it.The signals from the rotary are oke and the voltage's on the mainboard/front also oke.The strange thing is that non of the front buttons works but i don't get any errors when starting up the unit and also no keyboard error.No keys are "hanging" and all the rotary's are oke with the signals.

author: RajGowda
author_rank: Newbie
timestamp: January 30, 2020, 07:10:30 pm
content: Hi,Can you please send me the HM1004 oscilloscope service manual as I have problem in the OscilloscopeThanks & Regards
Repair help for a KSGER T12 Soldering Station - Page 1
Forum section: electronics / repair

author: Paul-H
author_rank: Newbie
timestamp: April 20, 2021, 03:30:38 pm
content: Hi allHope this is in the correct section for this, perhaps a MOD could move it if not.I have one of the KSGER T12 style Solder stations, in the handle there is a Thermistor used to read the handle temp but mine has never worked, I finally got around to checking it and found that the reason its never worked is because the Thermistor is snapped in half.Anyone with one of these stations do you know what value the Thermistor should be so I can fix it.It looks like it was a MF58 3950 type but they come in 10 different values from 1K ohm to 10M ohm, anyone know what the correct value should be.ThanksPaul

author: tunk
author_rank: Super Contributor
timestamp: April 20, 2021, 04:03:06 pm
content: Is this any help:https://www.eevblog.com/forum/reviews/t12-stm32-v2-1s-soldering-station-controller-schematic-etc/

author: Paul-H
author_rank: Newbie
timestamp: April 20, 2021, 06:48:23 pm
content: Excellent most helpful.10k is needed
Repair - help identify IC component 711 ?734 207M - Page 1
Forum section: electronics / repair

author: delmadord
author_rank: Regular Contributor
timestamp: December 29, 2022, 05:53:13 pm
content: This is ROLLER GRILL PIS30 induction plate. It died when "normal (non-inductive) pot was placed on top of it". Photos show the blown part, but my search-fu failed to provide any results about what it might be.I can see the following:711?734207MThe middle part is probably 1734. Any help appreciated.

author: fzabkar
author_rank: Super Contributor
timestamp: December 29, 2022, 06:58:41 pm
content: What are the date codes on the other ICs? That would help to identify the date code on your unknown chip.

author: delmadord
author_rank: Regular Contributor
timestamp: December 29, 2022, 08:57:12 pm
content: I think 2819

author: fzabkar
author_rank: Super Contributor
timestamp: December 29, 2022, 10:07:04 pm
content: U10 has "CHN 7 32". That suggests China, week 32 of 2017.https://www.st.com/resource/en/datasheet/stm32f301r6.pdf(page 129)This would be consistent with "1734", ie week 34 of 2017. That said, "711" could be week 11 of 2017 ...

author: gamalot
author_rank: Super Contributor
timestamp: December 30, 2022, 05:20:27 am
content: Try this:https://www.allegromicro.com/~/media/Files/Datasheets/ACS711-Datasheet.ashx

author: BILLPOD
author_rank: Frequent Contributor
timestamp: December 30, 2022, 08:42:58 pm
content: Good Morning delmadord, I have a similar induction hob, but a different brand. I have inadvertently placed non-steel pots on it and nothing was harmed, there was just no heating. Are you certain that is what caused your malfunction?

author: delmadord
author_rank: Regular Contributor
timestamp: January 02, 2023, 08:22:26 am
content: Quote from: gamalot on December 30, 2022, 05:20:27 am

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: January 02, 2023, 09:14:21 am
content: Is the transistor also dead? Might want to check before plugging it back in (should probably connect a lightbulb in series for safety).

author: delmadord
author_rank: Regular Contributor
timestamp: January 02, 2023, 09:51:58 am
content: Good point. Due to holidays, I will be able to put my hands on it for the first time on the 9th of January. Can I post here some updates by then?
Repair Help needed for Fluke 177 dmm - Page 1
Forum section: electronics / repair

author: nikosgr
author_rank: Newbie
timestamp: September 26, 2020, 02:28:47 pm
content: Dear Community Hi this is my first post here.I am trying to troubleshoot a used Fluke 177 dmm with no visible damage on the input front end stage (ptc is ok. (measuring 1,017 kohm) fuseble resistor is OK (measuring 1,0 kohm) mov"s are also OK (measuring OL in both directions after been de-soldered from the pcb)) additionally mode switch has been cleaned & new battery has been used.Problem description:Unit wont pass initial start up status (all digits and operation indicators in the LCD display "lets say" that are stack) and the meter is not passing to any measuring mode by rotation of the switch to any measuring mode.Any suggestions on how can this be fixed?

author: shakalnokturn
author_rank: Super Contributor
timestamp: September 26, 2020, 05:48:30 pm
content: Have you been through the usual first steps?Power, reset, oscillator, I²C bus...

author: nikosgr
author_rank: Newbie
timestamp: September 26, 2020, 06:43:07 pm
content: Dear shakalnokturn Hi,Thanks for pointing to the right direction.Power: any particular point that i can check on the pcb?Reset: if i am not mistaken this is done via the press of a dedicated baton located on the upper back side of the pcb.Oscillator: to check if the oscillator on the pcb located on the bottom of the lcd outputs a signal or not?I2C: i do not have a logic analyzer option on my oscilloscope.Thanks for your help and support

author: shakalnokturn
author_rank: Super Contributor
timestamp: September 26, 2020, 11:35:19 pm
content: I've never had to repair a Fluke 177 so I'll only be giving outlines.Unortunately I don't know of a schematic available for this model or any other Fluke using the same IC's.For power in most cases you can expect a +5V or +3.3V for the digital side of things. (CPU pins 38, 87 download HD6433844 datasheet)The analog (smaller QFP IC) will usually require an additional symmetrical supply somewhere between +/-1.5V and +/-3V.The quick way to look for the power rails is to measure on the tantalum capacitors and larger SMD ceramics relative to the COM input socket.As for reset I was not clear enough: I meant Power On Reset to the CPU. (Pin 15 must not be stuck low.)Oscillator check with an oscilloscope (and suitable probe) for right frequency and sufficient amplitude.For I²C if all previous points seem good, a sanity check with the oscilloscope should be good enough, you're mainly looking for bus activity on SCL/SDA with sufficient amplitude for CPU.
Repair help - Power Supply GW model GPC-3020, Master Channel not working - Page 1
Forum section: electronics / repair

author: MakerJeff
author_rank: Newbie
timestamp: May 14, 2020, 12:58:40 am
content: I have a used 3 channel power supply (Goodwill Instruments GW model GPC-3020) from craigslist that I want to get working to start an electronics workbench in my home workshop.The slave side and fixed 5v appear to work in independent mode. But the master side is dead in independent mode. In parallel mode the master side knobs and meter function. Nothing in series mode.I popped off the cover but couldn’t see any obvious issues. I couldn’t find a service manual or schematic for the machine online.I did find the front panel wasn’t installed correctly and a signal line was pinched by the case, so someone previously had been tinkering with it.Any ideas what the problem may be? Fuses all appear intact. No loose connectors. No burns on the traces or components. The master side relay doesn’t switch, I can hear the slave side working.I don’t have the confidence to start probing around without some guidance.

author: SpecialK
author_rank: Regular Contributor
timestamp: May 14, 2020, 02:56:15 am
content: Here's an owners manual with a block diagram that might be helpful.https://makerspace.jhu.edu/wp-content/uploads/2018/01/manual.pdf

author: tpowell1830
author_rank: Frequent Contributor
timestamp: May 14, 2020, 07:05:40 am
content: This PSU is also labeled as PS280 from Tektronix, with the difference being that the readouts are 7 segment on the PS280. I have the PDF schematic. PM me and I will send it to you.Also see the third comment reply on video.Hope this helps...
Repair help requested for Class D Subwoofer module of 18 inch 1000W amp module - Page 1
Forum section: electronics / repair

author: Studi-Jo
author_rank: Newbie
timestamp: September 23, 2024, 08:34:40 pm
content: Hi,I am 52, mobile DJ, and studied electronics 20 years ago. After that I never practiced.I have a DB Technologies DVA S10 18 inch subwoofer, 1000 Watts. On my last gig it started to smell....Decreased volume and had no choice to switch it off.Once at home I opened the enclosure and found a complete stuck 18 inch subwoofer, this occured the smell.Ordered a new one and installed it but when I power the active speaker, without any audio input connected, it immediately and always gives a weird soundIt's not a 50 Hz hum but a higher frequency resonance sound so there is also a problem with the amplifier.I removed the amplifier module "DigiPro 1000S" and opened it. Surprisely the Power Supply Unit is 3/4 of the module and only 1/4 is the amplifier.Found online the schematics:https://drive.google.com/file/d/1LB0oHgbkXONhuaymQSkRktFjN_DAph3A/view?usp=sharingBecause I need the subwoofer cabinet soon for other gigs, I ordered a complete new module but it would be nice if I was able to repair the old one and keep it as a spare. Visually I checked ELCO's and power components but nothing seems broken or smells burned.Started to check the output of the Power Supply Unit:New: +13,7 VDC (VDD) -13,7 VDC (VSS) -72,7 VDC (-HV) +72,6 VDC (+HV) -59 VDC (VDR)Old: +13,7 VDC (VDD) -13,7 VDC (VSS) -98,6 VDC (-HV) +98,5 VDC (+HV) -85 VDC (VDR)Old PSU gives more voltage to the amplifier MOSFETs but I guess this is not an issue.The PSU seems OK. How to proceed?The Amplifier has HEXFET Power Mosfets.Is it possible to check the state good/bad by unsoldering and measuring? I found datasheets from most important components.Any ideas or step by step instructions how to proceed would be highly appreciated!Thanks in advance,Johan

author: m k
author_rank: Super Contributor
timestamp: September 28, 2024, 05:41:25 pm
content: You have now four output channels, so even more comparing options.For more sophisticated stuff you need a more sophisticated picture.It's a low frequency stuff, so maybe an old scope is enough.
Repair help with Tek TDS620A - Page 1
Forum section: electronics / repair

author: keystone
author_rank: Contributor
timestamp: August 29, 2023, 08:49:50 pm
content: Asking for help with diagnosing a sick Tek TDS620A with processor fail. Can someone help me understand what the error message means that I got from the console port and also what is flash Id 4? What does that mean? Is that where the firmware is located and what would be the addresses of that if I wanted to down load it? Thank you for looking.