hybridfree/eevblog-posts huggingface dataset:
Brymen BM235 issue, nonresponsive, frozen display  - Page 1
Forum section: electronics / repair

author: jediger
author_rank: Newbie
timestamp: February 28, 2023, 04:06:30 am
content: I have the EEVBlog BM235 I bought years ago for use around the house. Whenever I turn it to any setting other than OFF it shows only the same few dark LCD segments and does not give any other indication of function. The backlight and continuity beep don't work either.I have:Changed the batteriesOpened the back upNext I am going to desolder the leads to the input board so I can fully disassemble it and inspect the dial and lcd contacts.Has anyone else has seen this?

author: Muttley Snickers
author_rank: Unknown
timestamp: February 28, 2023, 10:01:30 am
content: Quote from: jediger on February 28, 2023, 04:06:30 amWelcome to the forum.I was one of the first to receive Dave's BM-235 and out of interest I tend to monitor threads where it is mentioned but I don't recall seeing this type of failure before.Can you describe the last operation you did with the meter or did it just randomly fail in that manner?

author: jediger
author_rank: Newbie
timestamp: March 14, 2023, 05:39:30 am
content: Thanks for the response. I was measuring some voltages on my car and when I put it away it was working. I have moved since and it was packed away, life, etc. I was storing it in the garage. I'm not sure how hot it could have gotten, local summer highs can be 112F-114F (44C-46C). I found my order and the invoice date is Aug 20, 2016.I took pictures of the inside. The solder joints on L2 and L3 looks cold but they don't move when I poke them. There seems to be a slight scuffing around the dial contacts.I'm not sure what else to look at.

author: Muttley Snickers
author_rank: Unknown
timestamp: March 14, 2023, 06:45:58 am
content: Quote from: jediger on March 14, 2023, 05:39:30 amI can only suggest that you send Dave(EEVblog)a Private Message and include a link to this thread, he would be the best person to ask if a similar failure has happened to anyone else.

author: J-R
author_rank: Super Contributor
timestamp: March 14, 2023, 06:57:18 am
content: U4 looks odd in the photo, maybe just an optical illusion though?

author: 2N3055
author_rank: Super Contributor
timestamp: March 14, 2023, 07:11:27 am
content: Check if the CPU clock works at all (if you have a scope).

author: jediger
author_rank: Newbie
timestamp: March 15, 2023, 05:32:32 am
content: U4 did have something on it, maybe flux. It came off with a bit of alcohol.I'll have to take it in to the lab at work to use a scope, but I will follow that up.
Brymen BM235 Voltage read error - Page 1
Forum section: electronics / repair

author: adam01212
author_rank: Newbie
timestamp: November 05, 2024, 04:27:11 am
content: A while ago I bought a eevblog BM235. It has worked fine up until about a year ago…when I noticed it would not give a correct voltage reading and it would intermittently display 7.214/7.215V despite no probes attached to it. I was just wondering if anyone has seen anything like this before? And a possible fix?
Brymen BM257 probe jack faults - Page 1
Forum section: electronics / repair

author: glatocha
author_rank: Regular Contributor
timestamp: April 11, 2020, 04:00:15 am
content: Hi,I am asking you guys for any help to bring back to life my BM257. It served me well for over 10 years on both industrial and hobby usage.The problem is that is shows InEr on all settings except mAuA. I am suspecting that something is wrong with the leads detection. Normally this error is shown when I try to measure V/Ohms and the lead is plugged in one of the Amps inputs.So I am guessing something is wrong with the lead detection. It thinks the probe is still in mA when it is not? How does it work? what can I check to resolve the issue?Many thanks for any helpGreglinking Dave video with quick review:
Brymen BM257s DC volts + Temperature malfunction - Page 1
Forum section: electronics / repair

author: pazuwu
author_rank: Newbie
timestamp: August 22, 2022, 09:56:54 am
content: I've got a BM257s which started acting up recently.More exactly, when measuring temperature it displays a whacky value at room temperature, e.g. -149C. The temperature probe works ok with another multimeter.The second symptom I noticed a while after is filmed here:https://www.youtube.com/shorts/501oxSP0ymo.When selecting the DC volts range, without probes inserted, the display toggles between -3.000V and 0.000V. When connecting the probes, the multimeter keeps seeking a value ad infinitum, without actually displaying anything. And it doesn't show anything when connected to a battery either.Auto LoZ seems to have the same issue.Other functions seem unaffected.Normally, I'd send it in for repairs, but I haven't been able to locate someone who can do this in my country. I'll open the unit up and check everything I can think of, but since I'm pretty noob with electronics, I don't expect to figure out the problem myself.So I could use some hints about what could be wrong, maybe someone has a service manual too...?Thanks!Edit: added some hi-res photos of the boardhttps://drive.google.com/drive/folders/1a2uad6Ypdre2sfcD8KpZAJaUS_igxlNU?usp=sharingEdit 2: came across a video of Dave'swith another Brymen multimeter with a somewhat similar problem. Guess it's not trivial to fix such a thing.Edit 3: seems mine works on the DC volts if i manually force the range. Auto range seems to be the issue.

author: aduecho
author_rank: Newbie
timestamp: August 23, 2022, 08:13:23 pm
content: it seems not the HW issue, but the SW, the calibration data in the EEPROM seems lost or corrupt...
BSIDE ESR02Pro Component Tester repair - Page 1
Forum section: electronics / repair

author: gaminn
author_rank: Frequent Contributor
timestamp: May 07, 2024, 12:50:03 pm
content: Hi,I destroyed my ESR02Pro tester (tested charged capacitor). Now I get blank display with backlight on. Anybody managed to repair this? My main concern is whether the LCD has been also destroyed or not. If it is OK, then there is only a couple of ICs inside which can be replaced easily.Martin

author: tunk
author_rank: Super Contributor
timestamp: May 07, 2024, 01:07:39 pm
content: PCB photos please. If it uses a microcontrollerand it is damaged, then you need firmware.

author: madires
author_rank: Super Contributor
timestamp: May 07, 2024, 01:11:16 pm
content: Most likely the ATmega is damaged. The ST7565 based display is powered by a 3.3V LDO and has series resistors in the signal lines. So it might be still ok. You can find more information about that Transistortester clone athttps://disk.yandex.ru/d/yW8xa5NJgUo5z. And I'd recommend to run one of the OSHW firmwares (k or m).
Bside ZT302 rotary issues - Page 1
Forum section: electronics / repair

author: waste
author_rank: Contributor
timestamp: January 10, 2023, 11:46:27 am
content: I have one of these small but very convenient meters, but it has contact issues of the rotary selector. I opened the whole thing and I found out that the rotary dial is full of some fat . I don't know if I should better clean it or not. The traces are super clean and have no issues.Any people with experience on these units??thanks

author: waste
author_rank: Contributor
timestamp: April 17, 2023, 04:17:07 pm
content: To answer my own question for other people to profit from it, I had to add a little 3mm screw , a selflocking nut and a spacer to make sure you have enough and consistent contact. The attached pictures give a better idea

author: precaud
author_rank: Frequent Contributor
timestamp: April 18, 2023, 12:26:54 pm
content: Thanks, I've had one since it came out and will keep an eye out for that issue. Mine is good for DC and Ohms but the AC is very unreliable.
BT Dect phone parts of LCD display missing BT Studio 3100 - Page 1
Forum section: electronics / repair

author: martfoxy
author_rank: Regular Contributor
timestamp: April 24, 2021, 11:39:36 am
content: Parts of the digits etc are missing in the LCD display of this cordless phone (BT Studio 3100) - seems to happen with age. I expect there is nothing that can be done but I thought I would ask just in case.Thank you
BT YouView DTR-T4000 powers off  - Page 1
Forum section: electronics / repair

author: perdrix
author_rank: Frequent Contributor
timestamp: March 03, 2024, 08:20:31 pm
content: Powers up normally, then change channels and it powers off.Is there any hope to repair? Any common issues. If it can be repaired that's preferred as I don't want to loose all the HD recordings as I understand the HDD HD data is encrypted such that only that box can play back the recordingsThanksDavid

author: 807
author_rank: Frequent Contributor
timestamp: March 04, 2024, 03:58:30 pm
content: Have you tried a different power supply? Or tried any of the maintenance menu options?

author: perdrix
author_rank: Frequent Contributor
timestamp: March 04, 2024, 06:00:56 pm
content: I tried another power supply as I had one from an earlier Youview box - same problem died pretty sharply.Never get as far as maintenance menu.D.

author: 807
author_rank: Frequent Contributor
timestamp: March 05, 2024, 10:58:19 am
content: Quote from: perdrix on March 04, 2024, 06:00:56 pmHave you tried pressing the down arrow button for 5 seconds after first powering up the box? I believe the instructions for your box are the same as the T2000 shown here...https://support.youview.com/youview-box/box-and-remote/using-maintenance-mode/There are 5 options. 3 of them should keep your recordings...1. Software Reset2. Factory Reset , keep recordings (recommended)3. Factory Reset, delete recordings (if option 2 doesn't resolve your issue)4. Internet / USB recovery, keep recordings5. Internet / USB recovery , delete recordings

author: perdrix
author_rank: Frequent Contributor
timestamp: March 05, 2024, 12:33:04 pm
content: Now it won't stay powered for more than 10s after turn on! So I think I'm out of luck.All my soldering kit and meters etc. are in boxes after a house move and even if (as is likely) this is just failed electrolytic caps, I won't be able to replace them for weeks. So to keep domestic peace I've ordered another one from an eBay seller.D.
BTA416 600C triacs - Page 1
Forum section: electronics / repair

author: shockpoint
author_rank: Contributor
timestamp: November 08, 2024, 02:54:30 am
content: Hi all,general question here.Are triacs normally-open devices between MT1 and MT2?In addition, what's the relationship between MT1 and the gate terminal?Context - repairing a dyson AM04 heater fan.The triac in question is BTA 416 - 600C. The resistance between MT1 and Gate is 120Ohms and for a semiconductor this is suspiciously low. BUT, I have limited experience in triacs so this might really be normal behaviour. In support of this suggestion, there is another triac in a separate circuit (not parallel) with this triac, and MT1 and gate reads a similar resistance.This post here:https://www.eevblog.com/forum/projects/triac-question/suggests that the 600B variant measures 102ohms across said terminals.If it's normal behaviour, could someone explain why? In a Mosfet this would suggest a short but why is it part of normal function in a triac?

author: amyk
author_rank: Super Contributor
timestamp: November 08, 2024, 04:16:16 am
content: Quote from: shockpoint on November 08, 2024, 02:54:30 amYes.Quote from: shockpoint on November 08, 2024, 02:54:30 amhttps://upload.wikimedia.org/wikipedia/commons/thumb/6/68/Triac_structure.svg/576px-Triac_structure.svg.pngAlso worth givinghttps://en.wikipedia.org/wiki/TRIACa careful read.

author: MathWizard
author_rank: Super Contributor
timestamp: November 08, 2024, 04:34:26 am
content: Here's an easy to make tester for TRIAC's and SCR's, IDK where I foud this schematic, but it works with AC, or a DC supply to get the DUT conducting in 1 direction or another. Lately I tested a 600 or 800V heater TRIAC with some 16V in, and it passed some 100mA one way, and 82mA the other. IDK the minimum supply voltage for TRIAC's, but a 9V battery would work too.It read as 30 ohms, between M1/2. IDK, it's possible I overheated it removing it too, it was hard.
Btech Ham Radio Charger Repair - Page 1
Forum section: electronics / repair

author: Jake86us
author_rank: Newbie
timestamp: May 13, 2021, 01:23:48 am
content: Hey Guys/GalsI am working on a Btech charger for my UV-5x3 radio. I think I have blown the Linear Constant Current Charging Chip. The chip is pictured below in the attachment. My question is the chip is a HXN-WS e4956 and all I can find is a HXN-WS e4957. What is the difference between the 4956 and 4957? Can I use the 4957 instead?thanks for any help you may have!!Jake

author: Jake86us
author_rank: Newbie
timestamp: May 14, 2021, 12:43:07 am
content: Where is Dave at, I figured he would know!!

author: geggi1
author_rank: Frequent Contributor
timestamp: May 14, 2021, 08:01:49 am
content: Some time ago I found a page on the internet showing how to replace the original PCB with a generic charger circuit on the internet.I can not find this page again.These Btech chargers are supposedly unreliable.Here is a description on how to repair the chargers for the 878/868.http://members.optuszoo.com.au/jason.reilly1/868mods.htm#ChargerFix

author: Jake86us
author_rank: Newbie
timestamp: May 14, 2021, 12:23:44 pm
content: Quote from: geggi1 on May 14, 2021, 08:01:49 amThank you for the info! I'll keep an eye out form a repair tuturial on the btech changers.
Bugs in KSGER C245 - how to solve? - Page 1
Forum section: electronics / repair

author: repairMatthias
author_rank: Newbie
timestamp: May 18, 2024, 10:21:04 pm
content: I got a new KSGER C245. Unfortunately the software menu fails and the display output is not fully to see on the right side. Is there an easy fix getting rid of those problems? Are there schematics available for this device?

author: repairMatthias
author_rank: Newbie
timestamp: May 18, 2024, 10:25:14 pm
content: the character output is distorted. The device has to be switched off.

author: repairMatthias
author_rank: Newbie
timestamp: May 18, 2024, 10:28:17 pm
content: the °C text output is located too much to the right. The display should be shifted to the left.

author: DavidAlfa
author_rank: Super Contributor
timestamp: May 18, 2024, 11:08:59 pm
content: Seems like a connection problem. Check the solder joints.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: May 19, 2024, 05:32:33 pm
content: I agree with DavidAlfa that it's probably some connection problem. Maybe the flex to the display?There are a lot of variations of very similar soldering stations, and both schematics, (KiCad projects) and firmware for variants can be found on github / gitlab and similar sites.

author: repairMatthias
author_rank: Newbie
timestamp: May 20, 2024, 04:05:08 pm
content: the display is working correctly when powered up. So I do not feel that this is a hardware problem. This happens when using this menu. Switching off the device and on and its ok. But it will happen again when using the menu again.
Bulk power supply LY6806 based - Page 1
Forum section: electronics / repair

author: vidalv
author_rank: Newbie
timestamp: July 03, 2021, 08:18:12 am
content: Hello all, I am looking for a schematic or a data-sheet for the LY6806 circuit.On the websitehttp://www.stglsemi.com(which seems abandoned since 2014) nothing available.This circuit is used in a variable 3V-24V 3A cheap power supply.Thank you for any information.
Bullard MX Thermal Camera teardown/repair - Page 1
Forum section: electronics / repair

author: Real-Time
author_rank: Newbie
timestamp: May 01, 2020, 12:57:37 am
content: Hi all, I picked up a thermal camera for cheap on ebay a couple of days ago and I figured it would need some repair since it's 20 years old.I thought it was fairly simple inside, camera module was hooked to a Taiwanese LCD module by a 4 wire connector with a board in the middle to amplify the video and handle the batteries and what not.Here is the camera module.There was a little through-hole voltage regulator stuck to the outside of the camera housing.So now I know that I can feed this thing anywhere from 6.5 to 15.5 volts. I'll stick with 10 since that appears to be the battery voltage. I hooked up the voltage wires and the composite video to my monitor. At this point I was expecting to see the video feed, not this.This thing is more complicated than I had initially suspected.After a couple of seconds, we get the main user interface. The circular pattern is due to the camera, but the horizontal lines are in the video signal. The signal itself is pretty dirty and likes to jump around.So this is where I am, whatever is trying to generate the video signal is not happy, and I suspect that the culprit is a dirty power supply rail somewhere on the thermal camera side of the circuit board. The unit emits a high pitched whine while powered and has a strange smell to it. There are about 30 SMD electrolytic capacitors as well as 15 or so tantalums. The output of the 5v power supply glued to the side of the camera seems fine, but the 10v input power doesn't look great while the unit is powered.I've been looking into the chips on the board in order to understand how it works, and of particular interest is a BT866KPF digital video encoder. I'm pretty sure it overlays the green crosshair and scale onto the video output. Since I have video output, I assume that the circuit is good up to this point. There are separate inputs for the overlay and the base video.I really am not sure how to proceed at this point, though testing every voltage rail I can find would be a start. I'd appreciate any advice anyone can give me. I'll attach some additional photos at the end of the post.
Burnt circuit board jumper questions - Page 1
Forum section: electronics / repair

author: FullMoonFever71
author_rank: Newbie
timestamp: January 29, 2024, 05:47:20 pm
content: Good day everyone,As you will see in pic, there was an arc on this board (liquid spill) right at a high VDC point. I am attempting to add a jumper from pin 3 solder pad to the via hole circled on the top. I cant get the jumper pin in the via hole. Is there another way to jump the trace? I have attached a pic of the burnt lead and its twin right beside it.Many thanks!

author: wasedadoc
author_rank: Super Contributor
timestamp: January 29, 2024, 07:09:28 pm
content: Trace that via on the other side of the board and run the jumper from a solder point there.

author: Gyro
author_rank: Super Contributor
timestamp: January 29, 2024, 07:18:14 pm
content: Welcome.That board surface is pretty carbonized and probably conductive at HT. It needs scraping back to bare clean fiberglass before you proceed with the repair. If you want to use the via, then drill it out (it's not serving any useful purpose now anyway) and put the wire through, soldering to the track on the other side after scraping off the solder resist.
Burnt mosfet on power supply - Page 1
Forum section: electronics / repair

author: debi
author_rank: Contributor
timestamp: February 14, 2020, 10:10:27 am
content: Hi guys,i do have a problem with a PCB coming from a LG tv. I have a blown 5a fuse on the bottom right corner directly after plugging the power cable. After few test with my multimeter i found a burnt 24N60M2 mosfet... i tested almost all the components on the card unless the PFC/PWM controller IC. I saw somewhere it could be shorted as well.My electronic skils are limited so im sorry for this stupid question but could someone explain me how to test the PFC/PWM controller IC or any component that could be linked to the dead mosfet ? I found the datasheet of this IC but for me it s like reading chinese (ref 3BR4765JZ) : "Off-Line SMPS Current Mode Controller". (http://www.datasheetcafe.com/3br4765jz-datasheet-smps-controller/)I ordered the mosfet and id be really happy if replacing it would fix my LG TV but electronic is full of surprises.Thanks for your help

author: PKTKS
author_rank: Super Contributor
timestamp: February 14, 2020, 01:50:35 pm
content: Don't just replace the MOSFET and hope for the best.Usually the MOSFET shorted BECAUSE something else...You should replace the MOSFET and PRIOR to turningthings on again checking all caps related to that MOSFETYOU ARE REQUIRED TO USE A VARIAC WITH DIM BULBSto prevent another short... This will save you time and moneySMPS - in particular modern integrated and PFC models arenot trivial just replace and go ...You should also check 2 SMPS typical problems- LOAD SHORTs- SOFT START failures.This model in particular uses a 431 feedback loop whichrequires some thinking on the load/start procedure.NOT trivial .. random things will just be lucky shots. or notPaul

author: aqibi2000
author_rank: Regular Contributor
timestamp: February 14, 2020, 10:13:17 pm
content: And check diodes for shorts

author: debi
author_rank: Contributor
timestamp: February 15, 2020, 09:34:19 pm
content: Thanks guys for your messagesThe diodes are ok and caps tooA simple Dim bulb tester without variac could do the job ?im looking forward building this tester i never heard about it looks really useful.

author: wraper
author_rank: Unknown
timestamp: February 15, 2020, 09:45:07 pm
content: Quote from: PKTKS on February 14, 2020, 01:50:35 pmUsually MOSFET dies by itself. However often it also damages PWM controller and anything other connected to it's gate in the process.

author: PKTKS
author_rank: Super Contributor
timestamp: February 16, 2020, 12:26:47 pm
content: Quote from: debi on February 15, 2020, 09:34:19 pmYes. Probably will salvage the MOSFET front end to toastin the first try.Ideally the VARIAC would raise it safely.The BULB *SHOULD* do the bottom line trickPaul
Burnt out resistors - Page 1
Forum section: electronics / repair

author: jheatac
author_rank: Regular Contributor
timestamp: March 16, 2020, 01:18:41 am
content: Hello,I am verrry much an amateur at electronics.I am working on the power side of a car audio amplifier. Power transistors are smoked/blown apart.It also cooked the resistors directly in front of the power transistors. According to the schematics they are all carbon film, but they are blue 5% carbon film.Being that I can't read the bands, I am removing them and making notes of the resistance I removed.My question - Is there a typical fail mode of a resistor? I have several that the schematic says 100 ohm and they tested and 40-50 ohm and I have several listed as 2 ohm that tested 60 to 90 ohm. None were open circuit.I just don't want to blindly follow the schematic if this is indicative of anything.Thanks!

author: james_s
author_rank: Super Contributor
timestamp: March 16, 2020, 01:30:04 am
content: Typically resistors fail open or go up in value, it's very rare for one to drop in resistance. It's not uncommon for schematics to be wrong, sometimes it's an error, sometimes the schematic is for a slightly different model, sometimes the circuit was revised to improve some aspect.

author: WattsThat
author_rank: Frequent Contributor
timestamp: March 16, 2020, 03:11:44 am
content: If you cannot read the color bands because they’re smoked, use the schematic values as the actual resistance once they’re baked is no longer correct..As mentioned, resistors (typically) don’t go down in value when cooked, they go up. The resistors fail after the transistors fail since transistors almost always fail shorted, increasing the voltage/current through the resistors.

author: SpecialK
author_rank: Regular Contributor
timestamp: March 16, 2020, 03:42:08 am
content: Check out "The Active Region" youtube channel. Kevin makes pretty good videos on the subject.

author: jheatac
author_rank: Regular Contributor
timestamp: March 18, 2020, 08:38:20 pm
content: Thank you!
Burnt Resistor ID Help - Page 1
Forum section: electronics / repair

author: sudont
author_rank: Newbie
timestamp: September 17, 2020, 01:17:37 pm
content: While testing a late 80s sampler I'm repairing, I forgot to connect all the PCB to chassis ground screws, and found it blew a resistor,But without a service manual I'm not sure what to replace it with.I managed to find a pic of the resistor before it was burnt but it's pixellated, any help would be appreciated.It looks like it could be a 47G Ohms resistor according to resistor charts, but to me that's far too high a value to make any sense in the circuit?So maybe it's a 4.7ohm resistor?The resistor in question seems to connect the ground plane on bottom on PCB to top, unless I'm mistaken..

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 18, 2020, 03:14:24 am
content: Looks like yellow violet black gold (47Ω 5%).Tim
Burr Brown opamp 1506 / 15 datasheet wanted - Page 1
Forum section: electronics / repair

author: oz2cpu
author_rank: Frequent Contributor
timestamp: January 28, 2023, 12:19:16 am
content: I got a few of them, and wanted to play with them and test them, they are dated 1969 :-)anyone got a specification sheet ?i was able to find pinout and i know they ran at +13V and -13V in the circuit i took them from.but i like to know max voltage ? and expected frequency / gain curve ?offset and all that ?What i know so far :pin 1 : neg signal inputpin 2 : pos signal inputpin 4 : outputpin x : might be offset trim ?pin y : might be offset trim ?pin z : might be offset trim ?pin+ : positive supply voltage +13Vpin - : nagative supply voltage -13V

author: Kim Christensen
author_rank: Super Contributor
timestamp: January 28, 2023, 04:35:43 am
content: This handbook might be of interest to you:https://dl.icdst.org/pdfs/files/3db5f8cbbdc6f23fdea4d5d8231dbe96.pdfThey do show those X,Z,Y pins on a similar module on page 86, but I couldn't see any reference elsewhere to them. You might be more motivated to read more of it than I was.EDIT: On page 85 they show a 2K trimmer pot between X, Z, & Y... So your guess was spot on.

author: oz2cpu
author_rank: Frequent Contributor
timestamp: January 28, 2023, 09:29:18 am
content: thanks a lot Kim, that file is all i found too :-)that file does reveal pinout, but the model 1506 is not mentionened,it looks like there is a big difference in voltage ratings and speedwhen i look at the other type numbers,

author: picburner
author_rank: Frequent Contributor
timestamp: January 28, 2023, 05:53:08 pm
content: I don't know where he got this data, but in the description of this auction it states a maximum supply of +-18Vhttps://www.ebay.com/itm/361638771774
Bush Heritage 11 DAB+ Radio - Page 1
Forum section: electronics / repair

author: Wolfgang Felber
author_rank: Newbie
timestamp: March 24, 2024, 08:02:43 am
content: Hi to all, newbie here. My problem is I have a Bush Heritage DAB+ radio which is completely dead, nothing happens. I have checked the outboard SM power supply, works fine, got 12 volts on the multimeter. I did notice there is a voltage regulator that is red hot to the touch.Part no LD1117AL, surface mount device. I tested it, there was 6 volts going in and 240 milli volts coming out. Am I correct in assuming it is faulty? and can I get a replacement? I am trying to help a friend to repair it. Any assistance would be greatly appreciated. Thank you.How do you know what voltage the regulator is, there are no marking giving you an idea of the output voltage. help with this would be great as well.

author: tunk
author_rank: Super Contributor
timestamp: March 24, 2024, 02:32:56 pm
content: Photos?Wouldn't really know, but it could be that something "downstream" of the regulator has gone bad.

author: Wolfgang Felber
author_rank: Newbie
timestamp: March 25, 2024, 06:47:07 am
content: Hi all, after further investigation, I found there is a short circuit up stream of the regulator. I have removed the regulator but the SC is still there. I noticed there is a SC on the three SM capacitors to the left of the regulator. I have taken a photo of the position of the suspected SC.
But where is made the +12v on this Hameg312? - Page 1
Forum section: electronics / repair

author: GGMM
author_rank: Frequent Contributor
timestamp: March 08, 2023, 02:30:47 pm
content: Hello,This oscilloscope is repaired (pb of trace return that was visible), but I still have one last anomaly.Y amplification gives traces of 50HZ. Example if we visualize a signal it undulates.I tested the power supplies, no 50hz except on the test point +12v of the pcb vertical amp (about 20mv).No matter how I look at the diagram, I find all the tensions, but I can’t see how this +12V is created.Maybe I have a low view LOL.Can you clear upsee the schématic on this pdf at the endthank you for your help

author: jonpaul
author_rank: Super Contributor
timestamp: March 08, 2023, 02:43:37 pm
content: post photo of screen with no input or GRDJon

author: GGMM
author_rank: Frequent Contributor
timestamp: March 08, 2023, 03:05:51 pm
content: Hi,I found out where the +12v is.This is from +24V with Zenzer (see drawing)On the other hand, I don’t think it comes into play on the Y amp part, which seems more powered by 24V and 140V.I’ll give you a video of the anomalycdt

author: GGMM
author_rank: Frequent Contributor
timestamp: March 08, 2023, 03:58:57 pm
content: Hi,Pb solved.Resuming X and Y settings.However, I have one more question.I manufactured a resistance of 90MOhm by sering 15 resistors of 0.5 W to be as close as possible to this value.If I use my other oscilloscope with a probe (x10) so in theory 10 MOhm, I would like to do a quick test of the THT value (-2000V), so this should make a dividing bridge and the oscillo display -200V. r1 = 10mohm r2 = 90mohm, so the dividing bridge r1/(r1+r2)Possible?cdt

author: George Edmonds
author_rank: Frequent Contributor
timestamp: March 08, 2023, 04:23:30 pm
content: HiWill work at DC, but will not be compensated for AC.It is possible to get 2kV X100 scope probes from the likes of eBay for little money, just don’t hand hold them when in use.I do have one which has proved very useful, just be very careful with them.G Edmonds

author: GGMM
author_rank: Frequent Contributor
timestamp: March 09, 2023, 01:45:02 pm
content: hi,I did the test with my handmade probe. That’s great, I had exactly -200V on my oscilloscope, proof that it divides well by 10 the THT of -2000V.I took the opportunity to check the time base and amp Y.Everything seems okay.It’s actually nice to work on these old materials. Easier to repair. LOLcdt
buying a broken panasonic vp 5020a oscilloscope - Page 1
Forum section: electronics / repair

author: dh109f4
author_rank: Newbie
timestamp: June 05, 2025, 12:54:30 pm
content: I ordered a broken oscilloscope from facebook, seller stated the transistors get really hot when turned on. i dont know how hot it gets but apparently its "too hot" and he also said the vertical trace is bunched up, which sounds really vague. i tried looking for service manuals or schematics of it but i cant. can anybody maybe search the manuals or guess whats wrong with it for me please.(i only have one image of the thing)

author: dh109f4
author_rank: Newbie
timestamp: June 05, 2025, 01:06:51 pm
content: https://hirokun.jp/av/vp-5020a.htmla link to some info about it but i dont understand japanese so idk what it means

author: themadhippy
author_rank: Super Contributor
timestamp: June 05, 2025, 01:42:18 pm
content: Quotenor do i,but google translate turns it into perfectly readable english

author: dh109f4
author_rank: Newbie
timestamp: June 05, 2025, 02:30:36 pm
content: aight thanks mate
B&W ZEPPELIN AIR SOUND BAR - Page 1
Forum section: electronics / repair

author: geobee
author_rank: Contributor
timestamp: October 19, 2020, 06:25:26 am
content: Hi all, has anyone repaired the SMP supply in one of these, I believe they are a known problem, and difficult to get service info on. I have replaced several, but not all caps in the secondary, but even they tested ok for ESR once removed from the board. I would just replace the supply, but I cant seem to locate them as a spare anywhere. Looks like it will have to be a component level repair. The output voltages I believe are pretty standard, being 12 volt dual rails for the output amps, a lower dual rail for the pre amp supply, but not sure what this should be, and a 5 volt supply, which then returns to the board for the start up signal. So, I guess, if things do get difficult repairing to component level, and time is slipping by, I could probably cook up a patch in supply, but it would be larger, and may have to be external, but would be at least reliable. Unless someone has seen one of these Chinese made things, it is becoming a money loser for me, just a service to the customer if I do get it running. There are many SM components on the rear of the board, which do clock up the hours very quickly. Any ideas would be great. Cheers. Geoff
BWD 160A manual - Page 1
Forum section: electronics / repair

author: IconicPCB
author_rank: Super Contributor
timestamp: August 08, 2018, 06:01:46 am
content: I have just become a proud owner of a faulty BWD160A siggenny.I have been able to locate a manual for the non A model.Desperately looking for BWD 160A manual. Please help.

author: tautech
author_rank: Super Contributor
timestamp: August 08, 2018, 08:35:09 am
content: Yeah it seems Kevin only has the 160.https://www.kevinchant.com/bwd.htmlMaybe drop him a line, he's pretty helpful.

author: IconicPCB
author_rank: Super Contributor
timestamp: August 08, 2018, 09:44:09 am
content: Just as You say Tautech.I had sent him a message earlier of the day.Hopefully he may know of one.

author: JPereira
author_rank: Newbie
timestamp: December 28, 2020, 03:36:28 am
content: Just wondering if you did manage to get a 160A manual?

author: jasJOS52
author_rank: Newbie
timestamp: September 29, 2021, 10:57:06 pm
content: Hi, If you still need a copy of the 160a instruction manual, I have one I can scan. Includes instructions, circuit diagrams, parts list and differences between the 160 and 160a.Regards, Jim

author: IconicPCB
author_rank: Super Contributor
timestamp: September 30, 2021, 03:34:15 am
content: Hello Jim (why does Spike Milligan come to mind? or am i that old?),If You can please do.I do not need it presently however for the sake of completeness please do.

author: Oztralian
author_rank: Newbie
timestamp: September 25, 2024, 12:51:13 am
content: Hi jasJOS52 - Have a BWD 160A but still cannot find a manual for it - front panel buttons were missing - found and fitted salvaged buttons - works ok but rear panel outputs don't appear to be working. Have noticed mod on one web search jpg - 4 mm ground black socket added to rear panel. Would like to get hold of any details you have on offer - cheers

author: IconicPCB
author_rank: Super Contributor
timestamp: September 25, 2024, 11:00:45 am
content: The major and only difference is that the160A has an output buffer consisting of a FET/BJT stage whereas the 160 is without the output buffer,You can get a copy of 160 manual in one of the above posts.
BWD 539B CRO - Page 1
Forum section: electronics / repair

author: Loco1960
author_rank: Newbie
timestamp: March 13, 2020, 01:03:27 am
content: I have one of these old beauties but it has a problem, seems no horizontal timebase. The tube appears fine and has a single dot, focussable and movable in X and Y directions. Anyone experienced at fixing these?

author: james_s
author_rank: Super Contributor
timestamp: March 13, 2020, 01:15:32 am
content: Are you sure you are using it correctly? I've seen people have this symptom and it turns out they have the scope set in XY mode.

author: tautech
author_rank: Super Contributor
timestamp: March 13, 2020, 01:32:20 am
content: Quote from: Loco1960 on March 13, 2020, 01:03:27 amWelcome to the forum.Service manual if you don't already have one and for those playing along at home:https://www.kevinchant.com/uploads/7/1/0/8/7108231/539b.pdf

author: vk6zgo
author_rank: Super Contributor
timestamp: March 13, 2020, 05:13:12 am
content: Have you checked that ir works on X-Y?A common thing with some BWDs is the loss of internal triggering, which is because they source their trigger from the output to the horizontal plates, via a high value resistive voltage divider.The larger of the two resistors in the dividers goes high, reducing the trigger signal below the threshold.Do you get a "free running" display in "auto"?.If so, & you can control the sweep rate with the time/div control, try usiing an ecternal trigger signal.If it now triggers, the fault is as referred to above.

author: Loco1960
author_rank: Newbie
timestamp: March 13, 2020, 08:26:33 am
content: I misread the button positions in/out and indeed had it on X-Y
BWD504 pcb photo needed - Page 1
Forum section: electronics / repair

author: gkmaia
author_rank: Frequent Contributor
timestamp: May 12, 2019, 09:26:02 am
content: Anyone out there with a BWD504 who could send a photo of the PCB from the components side?

author: tautech
author_rank: Super Contributor
timestamp: May 12, 2019, 10:01:21 am
content: Here's the schematic:https://www.kevinchant.com/uploads/7/1/0/8/7108231/504_cro.pdfYou might find similar models might give guidance for the PCB.There's few from the 500 models here:https://www.kevinchant.com/bwd.html

author: gkmaia
author_rank: Frequent Contributor
timestamp: May 12, 2019, 06:17:13 pm
content: Thanks tautech.The reason I ask a photo is to check the orientation of some of the transistors. The type and orientation of some of my do not match the schematics.
C.E.C AMP3800 2x64W amplifier schematic - Page 1
Forum section: electronics / repair

author: xavlaur
author_rank: Contributor
timestamp: March 12, 2022, 07:20:50 pm
content: Hello !Maybe somebody has a schematic for CEC AMP3800 ?Initially had a humming noise on right channel, discovered floating ground on RCA input, rectified but after several hours come into protection mode, display: "ERROR".Somebody, few years before, repaired one of driver cards (the left one).I have no diagram and I need one.Thanks
Commodore C128D Power Supply - Capacitor Issue - Page 1
Forum section: electronics / repair

author: Chris2027
author_rank: Newbie
timestamp: March 02, 2024, 10:02:06 am
content: Hi all!!Okay so I recently began work on my old C128D which had no power. I'm not a fan of working with power supplies due to the high voltage in.The PSU has 2 transformers and 3 outputs9v AC+5v DC+12v DCAfter taking out the PSU, I found the 12v dc (yellow wire) was shorting to ground. After removing a few things I finally removed a capacitor which alleviated the short.The bad capacitor has the following written on it:470 /16FRAKOS 9So I took that to mean it is a 470uf 16V.I put in an Electrolytic replacement, which physically is much smaller (but I assumed this is just because newer components are smaller), and wired up the PSU to the switch.It looked good,the fan started up(Note: the Fan is on the +12v rail) and I was happy for about 5 seconds then a huge bang happened. I've taken a photo of the caps. The newly installed cap exploded!!So my question is that did I install a capacitor that was too weak? Did I misunderstand the writing on the old cap? Could something else cause the cap to blow up, which may have also caused the old one to fail too?In the screenshot the gold cap (left) is the original one, which is shorted (I have also tested on the cap itself, and confirm its definitely shorted).The black cap (bottom right) is what I had replaced it with, and the other (top right) is the exploded cap, It was the same as the black one.Any ideas?Thanks

author: eurgenca
author_rank: Regular Contributor
timestamp: March 02, 2024, 10:50:35 am
content: On the old cap, you have marked + on the new one you have marked - pole. Do you know this? If yes, check bridge rectifier.

author: Chris2027
author_rank: Newbie
timestamp: March 02, 2024, 11:27:56 am
content: Well I built up the courage to give it another go.. maybe I did put it in backwards??I double checked the orientation, and this time I connected the output to the C128's mainboard. This time the power is staying on and no explosion yet. Maybe it needed to be connected before switching it on?Chances are the fact that that theonlycapacitor that I replaced was the one to blow up most likely points to me being an idiot and installing it backwardsAnyway just going over it again seemed to help so thank you for taking the time to respond!

author: agent_power
author_rank: Regular Contributor
timestamp: March 02, 2024, 09:49:46 pm
content: If there's IEC power inlet filter can, remove it. Those tend to blow up and stink

author: pienari
author_rank: Regular Contributor
timestamp: March 03, 2024, 07:02:31 pm
content: I still wondering why to chance bad quality caps ?.Waist of time.

author: janoc
author_rank: Super Contributor
timestamp: March 03, 2024, 07:57:53 pm
content: Quote from: Chris2027 on March 02, 2024, 11:27:56 amGiven the explosion and the fact that the fan has powered up my bet is that you have, indeed, soldered the capacitor in backwards.Electrolytic caps don't blow up like that unless (very) hot or connected in the wrong polarity (which makes them hot).
C1568 transistor substitution? - Page 1
Forum section: electronics / repair

author: RiRaRi
author_rank: Regular Contributor
timestamp: October 05, 2023, 10:21:53 pm
content: Hello. I need to replace C1568 transistor in my National boombox but can not find replacement, or they are very expensive. Is there any modern substitution for this transistor?

author: fzabkar
author_rank: Super Contributor
timestamp: October 05, 2023, 10:39:59 pm
content: Datasheet for 2SC1568:https://media.digikey.com/pdf/Data%20Sheets/Panasonic%20Semiconductors%20ICs%20PDFs/2SC1568%20Datasheet.pdfJust do a parametric search at your component supplier's web site.NPN, TO-126B, 18V, 1A, 1.2W, hfe (Q = 90 - 155, R = 130 - 210, S = 180 - 280), 150MHz, low VCE(sat)

author: amyk
author_rank: Super Contributor
timestamp: October 06, 2023, 02:48:40 am
content: BD135/139 may be suitable.
Cable de audio M01 marca Baseus - Page 1
Forum section: electronics / repair

author: coyne80
author_rank: Newbie
timestamp: June 02, 2020, 08:35:04 pm
content: Necesito saber si este cable de audio M01 tendra una falla pues no trabaja al instalarlo desde el Headset Bluedio T4hacia el reproductor de musica. El cable tiene un conector tipo "C" macho y el otro extremo un terminal de 3,5 mm, he revisado si existe continuidad entre los pines del C y el terminal de 3,5 mm mostrando vvariadas resistencias entre ellos, es correcto o hay que reemplazarlo por uno nuevo?.Gracias anticipadas por posible ayuda.

author: coromonadalix
author_rank: Super Contributor
timestamp: June 02, 2020, 09:50:34 pm
content: Translated:I need to know if this will have audio cable M01 a failure it does not work because the install from the Headset Bluedio T4hacia the music player. The cable has a "C" type male and the other end terminal 3.5 mm, have reviewed continuity between pins of the terminal C and 3.5 mm vvariadas showing resistance between them is correct or there that new replacement ?.Thanks in advance for possible help.-------------------------------Foro de inglesThis is an english forum

author: Simon
author_rank: Unknown
timestamp: June 03, 2020, 06:52:59 am
content: Please only post in English.
Cable Header for Flir camera. need a part number (found) - Page 1
Forum section: electronics / repair

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: July 02, 2020, 05:46:21 am
content: HiI need a replacement for the beige header in the photo. Apparently it is from a Flir camera worth about AU $7000.Single row, 28 pin, 0.5mm pin pitch. I think the cable enters from the side. And it has a little brown plastic lock.Can anybody find a part number for this header.I melted the one in the photo trying to reattach it.Any advice on reattachment would be good too.I removed the ceramic cap, replaced the solder on the pads with 63/37 solder.but still managed to butcher the header hand soldering the pads back on.Very small amount of space between the header and the large chip.there are also other components on the underside of the board.

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: July 02, 2020, 05:58:01 am
content: maybehttps://www.molex.com/molex/products/part-detail/ffc_fpc_connectors/5052782833

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: July 02, 2020, 11:13:19 pm
content: https://au.element14.com/molex/52435-2871/connector-ffc-fpc-28pos-1row-0/dp/2781986?st=28%20position%200.5mmthis seems right.
Calculator scrambled screen (Ti-84 Plus Silver) - Page 1
Forum section: electronics / repair

author: MyHeadHz
author_rank: Regular Contributor
timestamp: January 24, 2020, 03:37:27 am
content: A calculator (Ti-84 Plus Silver) I haven't used in a while has a scrambled screen. Something apparently spilled on it a long time ago, as the syrup is hard.I disassembled and cleaned it with IPA, but no dice. There appears to be some of that syrup under some of the glass at the top of the screen, presumably bridging connections.Anyone know how to go about cleaning that display/LCD strip?https://i.postimg.cc/v8z5tLF3/contact-strip.jpgThe dark strips between the contacts are PCB and the lighter-colored strips are the sugary/conductive goo. I think the only last remnants of the goo are in that strip.I can take other pictures if you like.
calibrate philips pm2412A - Page 1
Forum section: electronics / repair

author: MatVer
author_rank: Newbie
timestamp: October 14, 2023, 02:33:41 pm
content: Hello, I recently purchased a Philips PM 2412A, and it is functioning properly. However, when I set the scale to 1V and give the meter exactly 1V with my lab power supply ( which I check with the fluke 289 which is resent calibrated), it seems to go slightly out of range. How can I calibrate this meter?Kind regardsMathis Verschueren

author: coromonadalix
author_rank: Super Contributor
timestamp: October 14, 2023, 03:14:47 pm
content: schematici think 1st you should measure the trimpots values on each side of the wiper / center pin to be sureR10 seems for ACR37 i think is for dcR27 seems resistanceseems to be 2 - 5 % precision depending of the function, if it's the case i would calibrate it at the center value say 50 ... it is not an precision instrument ...close values should be enoughin no ways it will compete with more modern equipment

author: MatVer
author_rank: Newbie
timestamp: October 14, 2023, 03:28:03 pm
content: but i see only 2 potetiometers of 1kohm

author: coromonadalix
author_rank: Super Contributor
timestamp: October 14, 2023, 04:05:50 pm
content: oh my bad, one must be on the front panel lollthe zero ohms adjustmentpictures would be nice ...