hybridfree/eevblog-posts huggingface dataset:
Toroidal transformer orientation - Page 1
Forum section: electronics / repair

author: shakalnokturn
author_rank: Super Contributor
timestamp: March 23, 2024, 11:23:37 pm
content: This is an already solved problem, I'm curious to hear if other people have run into this before and the explanation behind it.I had a AER guitar amp to repair with a defective toroidal power transformer. 60VA, 2x115V series primary, 2x15V parallel secondary.The transformer supplies an internal AGM battery and inverter for the power amplifier supply voltage. It's mounted under the charge / inverter PCB and furthest away from the high gain stages.I thought the replacement would be straightforward, it was a tight fit, the replacement being slightly more powerful and bulkier than the original (not larger enough for distance to have significant effect on radiated fields). Once replaced there was some 50Hz hum. The owner confirmed this was not the case before the transformer replacement so I went back and re-checked wire routing.In the end the hum was eliminated by rotating the transformer around it's mounting axis by 90° having the wires rather counter-intuitiveley right against the inverter PCB.

author: Jwillis
author_rank: Super Contributor
timestamp: March 24, 2024, 05:38:32 pm
content: In theory the field should be confined just to the core as the outer field plain should cancel the inner field plain. But the math is based on ideal conditions and as we all know reality isn't always ideal. Some stray magnetic flux will escape because the outer winding's are not evenly spaced with the inner winding's. But if you look at the toroid in 3 dimensions, the top and bottom winding's are evenly space with respect to each other. So much better cancellation of the fields can be achieved on the top and bottom plains. Defects in the core contribute as well to how much the fileld will stray from the centre of the core. The size of the core and number of winding's also effects the amount leakage. This phenomenon is also applicable to toroid chokes. By placing multiple toriods with the tops and bottoms parallel to each other, neither field will effect the next as much as when the toroids are placed with the outer perimeters side by side. This effect can be observed with an AC Gauss meter.
Torqueedo Cruise 10 - shaft PBC Board repair - Page 1
Forum section: electronics / repair

author: pcdoctor03
author_rank: Newbie
timestamp: June 25, 2025, 10:28:32 am
content: On the control throttle of my Torqeedo Cruise 10 motor, after starting, an E47 error is displayed. Apparently, this is related to damaged PCB boards located in the lower part of the motor and responsible for all the control functions. The manufacturer is ignoring the issue and refuses to sell new PCB boards for testing and potential replacement. Is there anyone here who has access to the schematics of these boards and could share them so I can check what exactly is damaged?Thank you in advance and best regards.
Toscal BC-1411 calculator no schematics - Page 1
Forum section: electronics / repair

author: strawberry
author_rank: Super Contributor
timestamp: June 09, 2022, 09:56:42 am
content: schematics or possible reverse engineering

author: m k
author_rank: Super Contributor
timestamp: June 13, 2022, 10:14:32 am
content: Very nice, and seems that Yen has had a small value for quite some time.But was there a question?At least the pictured repair man didn't need many papers.

author: strawberry
author_rank: Super Contributor
timestamp: June 13, 2022, 11:13:43 am
content: schematics not for repairs
Toshiba 40L3400U screen blemish (dark spot) - Page 1
Forum section: electronics / repair

author: RogerAF
author_rank: Newbie
timestamp: December 06, 2022, 08:54:21 pm
content: My screen has a small area that looks almost scorched, or just dirty. I tried scrubbing the surface, but it seems to be on the inside of the plastic outer screen. It isn't a problem if someone's dark hair is in that area, but when there are lighter colors, it becomes annoying. I think I need to remove the outer screen and try to clean it, but I have no experience in this area. Does anyone have any suggestions, or seen this problem before?Thanks very much.
Toshiba 55U5766DB LED TV switches off after approx 10 seconds - Page 1
Forum section: electronics / repair

author: nevillet
author_rank: Contributor
timestamp: August 04, 2019, 09:44:40 am
content: Hi All,I am trying to repair a friends TV which switches off after about 10 seconds. I thought the problem might be the Vestel 17IPS72 PSU board and i've checked all the electrolytics and the diodes. All are fine.The Vestel logic board is a 17MB120.Any pointers would be most welcome.Thanks

author: m3vuv
author_rank: Super Contributor
timestamp: August 05, 2019, 10:11:36 am
content: i would start by checking the psu outputs firstly,ie see if they all vanish when it turns off.

author: nevillet
author_rank: Contributor
timestamp: August 05, 2019, 05:41:46 pm
content: Thanks M3VUV,It turns out that the psu board is OK.I've figured out a work around to make it work: After switching on you select an external source, like a video file on a USB stick. Once it is playing you can return to the TV tuner and it continues to work fine. You have to repeat the process after switching off/on.A bug in the firmware perhaps? No updates are available on the Tosh site. From new in 2017 it was fine and has only developed the issue over the last few weeks.

author: m3vuv
author_rank: Super Contributor
timestamp: August 13, 2019, 05:34:00 am
content: certainly an odd ball fault!

author: KRISTOFFER
author_rank: Contributor
timestamp: February 02, 2021, 10:13:33 pm
content: I found the following after some research. Novatek manufactured the NT72563 chip. Vestel manufactured main AV boards fitted with this chip. Vestel manufactured televisions containing these boards. Toshiba, JVC, Bush, Polaroid, Logik, Luxor, Turbox etc sold the televisions with their own logo on and start up logo as their own brand. Even when set to automatically update software, they do not. In 2018 the original software was adequate for on demand channels etc. Two years later they still have the 2018 software and applications software resulting in them turning themselves off then back on again. At this point they will take all other devices connected to your hub out.The Vestel boards fitted with Mstar MSD93F3PK2 do update and continue to work. No one is accepting any blame. IF you are lucky enough to get a USB stick from your manufacturer with a software update, it will not work.
Toshiba T4700 series and T4800 bios update - Page 1
Forum section: electronics / repair

author: poot36
author_rank: Frequent Contributor
timestamp: December 30, 2023, 09:24:30 pm
content: Here is the files for upgrading or recovering the bios for these models T4700CT, T4700CS, T4800CT. The file is actually a rar extension so you will have to delete the zip and change it to rar. The readme file provides instructions on how to use the files. I have included the original exe file in the rar file as well as the extracted content of the exe file.
Touch Screen Garmin 8612xsv - Page 1
Forum section: electronics / repair

author: RICARDO RIBEIRO
author_rank: Newbie
timestamp: August 29, 2025, 04:04:55 pm
content: Dear all, I have a 12" touch screen from a Garmin GPS, where the glue between the touch and the display has slipped, probably due to heating from the sun, and I would like to know what type of glue this is. If anyone can help me, I would be very grateful in advance. To make things easier, I will post a photo of the problem"

author: Swake
author_rank: Frequent Contributor
timestamp: August 29, 2025, 07:06:47 pm
content: Don't know about your particular case but I remember about something that might help finding a solution: back in the day of the first screen replacements for mobile phones there was a glue to fix the glass to the digitiser and the LCD.

author: Koray
author_rank: Regular Contributor
timestamp: August 31, 2025, 07:03:55 pm
content: You probably have to separate the screen from front glass, and clean the old adhesive residue. Then apply Liquid optically-clear adhesive (LOCA) and cure it with UV light. Search YouTube for application process to avoid bubbles.
Toyota Supra MK3 Direction Indicator Module mod - Page 1
Forum section: electronics / repair

author: ceut
author_rank: Regular Contributor
timestamp: October 15, 2022, 03:44:24 pm
content: Hello,I have taken the Toyota Supra MK3 Direction Indicator Module.With one of my best friends, we want to put leds everywhere without putting resistor for simulating current consumption.So I have reversed the schematic, and mod the IC to flash at the normal speed, without checking anything.This IC is about the same as all Direction Module IC (U243B/U2043B/UAA1041) but with another reference on it.I have taken some hours to understand how it works, and I find that it is a really great developped ICwith checking about everything (over/under voltage , over/under current, shortcut detection).Here is the schematic I have made to mod it, and I have put a video on Youtube.This IC seems to be widely used, so hope this will help some of youCheers

author: ceut
author_rank: Regular Contributor
timestamp: October 21, 2022, 03:46:49 pm
content: An unexpected (and funny) thing has happened when we test my mod yesterday evening at my friend's house:After plugin the indicator module: it starts to work without activating any directionSo only the clicking noise of the relay at normal speed without any direction ledI have understood that the IC is powered ON when the ignition is done (even without the motor).So I have added another transistor (PNP) for checking the current flow on the ouput pin.Here is the updated schematic
TP-Link HS110 smart plug flash - Page 1
Forum section: electronics / repair

author: Khaveer
author_rank: Contributor
timestamp: September 17, 2020, 09:56:40 am
content: Hey everyone. I've been trying to repair a faulty HS110 smart plug. It seems to be a quite pupular and hackabe unit. Unfortunately those devices seem to develop a fault after a while. The status LED stays amber all the time which indicates the unit is still booting. It is not responding to the factory reset button. After poking around the UART interface I've noticed that the device is stuck in some sort of a boot loop. I wanted to dump the flash memory to verify that it's not corrupted. Somehow I've managed to damage the flash chip in the process. Is there anoyone who's been poking anound those devices and is willing to try to make a dump for me? It appears that the only way to do it is to desolder the chip and read it using a programmer.
TP.MS3463S.PB801 board failure, need advice - Page 1
Forum section: electronics / repair

author: CurrentBitesOnlyOnce
author_rank: Newbie
timestamp: December 02, 2020, 02:28:17 pm
content: Hi ppl,i have a lcd tv which suffered lightning strike, red diode is on but you can not power on the tv it is not possible to switch it on. I did some work and i believe i have diagnosed it correctly. Board is TP.MS3463S.PB801 and main chip (they call it lcd chip but for me it is microcontroller or maybe microprocessor) is MSD3463GSA. Very soon as you plug it to the wall the chip gets hot maybe in a minute, i did some voltage checks and looks like all arround the pins the voltage is 3,4v suggesting internal short in the chip, also some voltages are missing for example 1.15 or 1.something v. Since markings on the diagram are poor and there are some abbreviations which i am not familiar of i am stuck and cant figure out what are the inputs and what are the outputs but i am pretty sure the chip is gone. I assume that most of 5v and 3.3v are voltage regulated power supply and those voltages of 1. and 0. v are probably outputs of a chip, am i right?Looks like other stages are just fine there is power to the usb and hdmi ports, there is power out of the switcher looks like the levels are correct, so it looks like the chip itself is bad, but before i test the rest and change the chip eventually i need to know how hard is to change the chip?I guess it has to be programmed?Do you need special equipment?Can you buy already preprogrammed chip for that specific board?Can it be programmed on the board or has to be on the bench?Help and advices are apprecieted.Thanks.

author: CurrentBitesOnlyOnce
author_rank: Newbie
timestamp: December 04, 2020, 11:56:07 am
content: Nothing? Zero? No one?
Trace fuse - Page 1
Forum section: electronics / repair

author: richardsuperstar
author_rank: Newbie
timestamp: July 12, 2021, 01:02:19 pm
content: Hi,I am in the process of doing a few jobs on my car. One of which is the throttle body or anti shudder valve as i guess it is technically called being it is a diesel.I thought i would be lucky and get away with just cleaning the contacts and away we go but upon opening it i discovered a much more tedious issue.It would appear that on the 12 volt pin there is a trace fuse that has blown. If I check for continuity across the solder points then there is an obvious break. I have attached photos so hopefully they will appear if not the break can be seen in the youtube video link.Now of course I could just get a replacement from BMW but they dont seem to be cheap especially when I can see the issue.I managed to find a video on youtube where someone had the same issue. 5:20 Minutes inIn the video he uses a strand of wire to bridge the gap but I'm thinking of going the more elegant fuse route so here is my question...What kind of rating would anyone hazard a guess at this being or would a strand of wire be good enough.Many thanks

author: perieanuo
author_rank: Frequent Contributor
timestamp: July 13, 2021, 03:28:45 pm
content: hi,the fuse trace is simple to repair, you take some 1mm2 copper multi-strand conductor and the thinnest wire take 4-6 amps. approximate the max current for the motor, take some margin like 50-100% and that's your fuse, or approximate the track's sectionBUT you have to verify transistors on that pcb or shorted capacitors or even that IC may be badregards
Traco TXL 60W PSU repair - Page 1
Forum section: electronics / repair

author: 1980s_john
author_rank: Contributor
timestamp: December 10, 2019, 07:37:45 pm
content: Hi,Here are my notes on repairing three of these units, luckily very simple fixes.The first was a the Traco TXL 060-0533T, which has three outputs, V1 =+5V adjustable, V2 = +15V fixed and V3 = -15V fixed. Fault was -15V output gave -1V and +15V output gave +6V, it has a single indicator LED which was not lit.First saw that C37 (-15V smoothing capacitor) was bulged, replaced with 450uF 35V low ESR. This caused -15V output to become -6V, +15V still only +6V. Started to look at primary, unsoldered mains input capacitor (C5, 150uF 400V), measured at 60uF so replaced - no change.Looked around for any other suspects, unsoldered C12 (47uF 50V) and found it was nearly shorted. Replaced and all outputs now OK, LED lit. Tested up to 1A load, very little voltage drop.I think C12 might be in the starter circuit but I don't have a schematic.The second was another TXL 060-0533T, this had no outputs. The main 150uF 400V cap measured 100uF but I decided to leave it in. Again C12 and C37 measured very low, replacing just these two restored normal operation (only tested to 1A out on V2 and V3 only as that was all the application needs).The third unit was a newer variant, TXL 060-0533TI, fault was LED came on then went out, no output voltages. This has the same voltage and power rating, but separate grounds for each of the three outputs. Also the spec says V1 has to have a load to allow V2 and V3 to be regulated, so I used a 10 ohm 10 watt resistor (not needed on the earlier units). Draws 0.5A @ 5V so barely warm.Inside it looks very similar to the earlier unit, a few changes here and there (eg no obvious fuse), and easier to remove the heatsinks.I checked the main 150uF 400V cap and this was only 75uF but I again I left it in. Only C12 measured very low, and replacing this one cap (with a 47uF 63V one) restored normal operation, with 1A on V2 and V3.Regards,John
Trak Systems 8900-9 Dual Rubidium Frequency Standard - Page 1
Forum section: electronics / repair

author: gdnichols31
author_rank: Regular Contributor
timestamp: December 18, 2022, 03:07:39 am
content: I just purchased one of these off Ebay and I'm wondering if anyone knows anything about them. I haven't been able to find much on the web. The Rubidium Oscillators seem to work, but it has other problems. It also has 2-5MhZ Oven controlled Oscillators that work. Both power supplies work. Everything is redundant. There are 3 output distribution boards and they seem to have a problem. When plugged in they generate a fault. Of course I don't get any 10 MHz output at all. I do have a 5 MHz output.I believe this was part of a Motorola Multicast Radio system.Does anyone have a operations manual or schematics?I searched for Trak System here and didn't find anything.See pics below;[ Specified attachment is not available ]

author: gdnichols31
author_rank: Regular Contributor
timestamp: January 09, 2023, 03:10:03 am
content: Wow I must have the only one on Earth.This long and no replys???Gary

author: Bud
author_rank: Super Contributor
timestamp: January 09, 2023, 04:25:24 pm
content: If it was part of a telecommunication setup you may never find manuals let alone schematics. Maximum what you may find is a general description how it fits into the system.

author: bingo600
author_rank: Super Contributor
timestamp: January 09, 2023, 04:27:06 pm
content: Seems like one can buy a manualhttps://www.booksimple.website/product/Trak-Systems-8900-Gps-Controlled-Oscillator-Frequency-Standard-Manual-Copy_91bjolppjollllk.htmlBut i doubt it contains schematics etc ...

author: gdnichols31
author_rank: Regular Contributor
timestamp: January 09, 2023, 06:13:42 pm
content: Thanks for the link to the book. I hadn't seen it before. I ordered it.I'm sure it won't have schematics either, but it's more than I have now.I was hoping maybe a tech for the company might be on the board with an old service manual.......One can always hopeGary
Transformer - Page 1
Forum section: electronics / repair

author: AirScooter
author_rank: Contributor
timestamp: March 31, 2021, 06:10:27 pm
content: This is the schematic of the power supply on my Fluke 8000A Bench Multimeter.The transformer gave up the ghost after 50 years of service. I'm trying to find a replacement for it.It's a through hole mount 5 studs through the board to a side. The output side has one stud cut off. It outputs +5v and +15v DC, 115AC mains.The Fluke part is #345629. (No longer supported by Fluke) The Manufacture Supply Code is 89536. I am looking for a physical size in the manual but so far coming up short. If you need more/different information let me know.Thanks,Dave Lowa

author: bdunham7
author_rank: Super Contributor
timestamp: March 31, 2021, 06:24:04 pm
content: Can you post a photo of the board and the revision number?

author: DLJ
author_rank: Contributor
timestamp: March 31, 2021, 06:53:11 pm
content: Which transformer do you suspect? The schematic you have attached has two.T1 is used to generate 5V, and T2 is used to generate +15V and -15V from that 5V.Does the meter still work on battery power?It would appear that there are at least 3 different variants Of the Fluke 8000A - the service manual show the schematics for these. Each has a different PSU. Which one do you have?

author: AirScooter
author_rank: Contributor
timestamp: March 31, 2021, 09:14:51 pm
content: Super Question, but we'll have to wait till tomorrow to find out. Have to wait for the supplier and his questions to get back in the office.

author: AirScooter
author_rank: Contributor
timestamp: March 31, 2021, 09:32:05 pm
content: Here you go bd..........Thanks for your help!

author: bdunham7
author_rank: Super Contributor
timestamp: March 31, 2021, 10:17:25 pm
content: You have the wrong schematic. How do you test the transformer?

author: bob91343
author_rank: Super Contributor
timestamp: March 31, 2021, 10:46:01 pm
content: The OP's diagram shows a battery operated unit; the battery runs a square wave oscillator that generates the voltages for operation. The diagram above shows no battery, just a simple TR with simple regulators.
Transformer from SMPS with coils not connected to anything? - Page 1
Forum section: electronics / repair

author: gmc
author_rank: Regular Contributor
timestamp: November 17, 2022, 10:32:28 pm
content: I'm busy trying to repair a SMPS from a IBM XT Computer from the 80's and unfortunately there is no schematic so my first order of the day is to reverse engineer the PCB.I've been looking at the high voltage transformer which I removed and was beeping out and thought it was faulty as 2 of the wires are not connected together. I thought they were another winding.I thought this a sure sign of a failure. Was just about to rip it apart (This looks like a point of no return as there is no way to reassemble) to confirm my suspisions when I traced the 2 suspect wires.One goes to earth and the other to 380V DC in - so they can't possible be joined!What kind of sorcery is this if they are not connected to any of the other coils. Is there some magic about transformers I'm missing?I've attached some pics of the transformer - I know it's going to be impossible to probably tell from the pics what's going on but maybe someone has seen something like this and can offer a reason why this is done? Only possible thing I can think of is it's for noise reduction?I've drawn a symbol of how the coils are connected (not 100% sure about the pri/sec sides) but the interesting ones are bottom left.

author: DavidAlfa
author_rank: Super Contributor
timestamp: November 17, 2022, 10:41:55 pm
content: Must go somewhere, otherwise you might have found the problem.Was any of the primary transistors shorted/blown?A huge current spike like that can damage the coil if the wire is thin enough.

author: Gyro
author_rank: Super Contributor
timestamp: November 17, 2022, 11:02:19 pm
content: They could well be electrostatic screens for EMC reduction.

author: gmc
author_rank: Regular Contributor
timestamp: November 18, 2022, 07:19:36 am
content: I've rechecked and they are definitely not connected to any other pins on the transformer. II've checked all the transistors, diodes etc and can't find anything that is shortted.

author: gmc
author_rank: Regular Contributor
timestamp: November 18, 2022, 07:21:03 am
content: Quote from: Gyro on November 17, 2022, 11:02:19 pmI think you might be right, this is the only possible explanation.I think it's time to get a differential probe and start checking through the circuit.
Fix an winding arching transformer - Page 1
Forum section: electronics / repair

author: gkmaia
author_rank: Frequent Contributor
timestamp: July 29, 2019, 04:36:51 am
content: I am fixing a vintage tektronix oscilloscope that was blowing fuses.Wen to inspect the transformer with a HV insulation tester. Some of the windings are arching and I will need to re-wind it.I've winded transformers before and got the tools for that but never put one a part with the intention of preserving some of the windings.Need some ideas on how to melt the wax/rosin to release the iron plates without damaging the enamel of the original windings in case I can preserve any.By looking at some datasheets I come across values likeTemperatue indexHeat shockCut-throughWhich one of these values relate to the maximum temperature the enamel resists before getting melted?
Transformerless power supply and relays. - Page 1
Forum section: electronics / repair

author: Yamin
author_rank: Frequent Contributor
timestamp: March 19, 2022, 05:11:52 pm
content: Hi,I've got in a refrigeration system with a universal type relay module which became faulty. Its made up of 4x 12V relays and the power supply is a transformerless design (not a huge fan of this).My first thought was why aren't there any 12V zener diodes? After some browsing on the web I came across this website:https://www.homemade-circuits.com/cheap-yet-useful-transformerless-power/Quoted from the site - "However, the 310V DC may be too high for any low voltage deviceexcept a relay. Therefore, an appropriately rated zener diode is used for shunting the 310V Dc into the desired lower value, such as 12 V, 5 V, 24 V etc, depending on the load specs."Why is the zener diode omitted for relay circuits?Troubleshooting the circuit I found out that the current limiting resistor R1 10 ohm resistors were out of value. I replaced them with the same Watt but 12 ohm resistors since I had them in my parts bin.Another thing I noticed was that flyback diode across the relay coils were also omitted. So I added flyback diodes across the relay coil. Could there be a reason why the flyback diodes are not originally installed and could putting them in be detrimental?The unit works now. I hope you could shed some light on the question I have.Thanks in advance.*I'm using an isolation transformer while troubleshooting this circuit.

author: Kleinstein
author_rank: Super Contributor
timestamp: March 19, 2022, 05:14:55 pm
content: With a constant load (the realy always connected) there is no need for an extra limiting of the voltage. In some cases also the diodes at the rectifiers could be zeners and do the limiting.

author: fzabkar
author_rank: Super Contributor
timestamp: March 19, 2022, 09:21:33 pm
content: When you interrupt the supply to the relay (by switching off the active terminal), the 4 rectifier diodes become the back-EMF suppressors for the relay coil.

author: Seekonk
author_rank: Super Contributor
timestamp: March 19, 2022, 09:30:13 pm
content: Those resistors in series with capacitor often fail. That is how I get a lot of free stuff.

author: EHT
author_rank: Frequent Contributor
timestamp: March 19, 2022, 10:48:16 pm
content: I suppose the purpose of this circuit to make the relay work with 110 or 240v AC input, otherwise they could just have coils rated at the line voltage. The 2 caps might also be likely to fail..
Transistor 4F3 Marking - Page 1
Forum section: electronics / repair

author: 2X
author_rank: Frequent Contributor
timestamp: June 01, 2022, 09:32:07 pm
content: Hello,I have a PCB for an Air Condition unit where two transistors blow. As I saw from a picture that a friend send me the one it has a marking 4F3 and the other CQ43... does anyone knows what transistors are.. I can't find any datasheet and I can't understand what type the transistors were and which pin is B-C-E. The Q14 transistor connected at the anode of the D22. Also, I don't find the role of the D16 and D22 diodes in the circuit.The Air Condition brand is Hitachi and the model of the PCB is PI023-2 (I couldn't find any schenatic - If anyone knows where can I find the schematic please inform me).

author: fzabkar
author_rank: Super Contributor
timestamp: June 02, 2022, 05:21:17 am
content: http://www.smdmark.com/en-US/search/code?id=cqhttp://www.smdmark.com/en-US/search/code?id=4fhttp://www.smdmark.com/en-US/search/code?id=cj

author: gamalot
author_rank: Super Contributor
timestamp: June 02, 2022, 06:26:30 am
content: CQ 2SK2411Khttps://datasheet.octopart.com/2SC2411KT146Q-Rohm-datasheet-61695489.pdfCJ 2SB1002https://4donline.ihs.com/images/VipMasterIC/IC/RNCC/RNCCS00915/RNCCS01556-1.pdf?hkey=52A5661711E402568146F3353EA87419
Transistor BFY90 replacement / equivalent - Page 1
Forum section: electronics / repair

author: Wawavoun
author_rank: Regular Contributor
timestamp: October 07, 2021, 10:52:53 am
content: Hello there,In the following circuit I replace the BFY90 by a 2N2222.The highest frequency come from the shift register LS165 and is 16 MHz.Will the assembly work with same performances with this change ?With the datasheets I think yes but I am unsure.I have no measurement system at such frequency. My scope is 20 Mhz bandwith so it show nothing serious at 16 MHz.Thanks for help and explanations.Regards.Philippe

author: Kleinstein
author_rank: Super Contributor
timestamp: October 07, 2021, 11:53:28 am
content: The BFY90 is quite a bit faster and lower capacitance than the 2n2222. So it would be a bit slower. The input side looks like is is reasonable low impedance, so it may still work, but it depends on what the ouput is used for.

author: Wawavoun
author_rank: Regular Contributor
timestamp: October 07, 2021, 12:09:09 pm
content: The output feed the composite video input of lcd tv.Today the tv (which works well with similar others systems) dont show anything.All the board is new and debugging is on the way but far from finished so I do not incriminate the 2N2222 at this moment.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 07, 2021, 01:57:38 pm
content: Composite video should be OK, as the frequency is limited (AFAIR some 6 MHz). So a slightly slower transistor should not be a problem.

author: edavid
author_rank: Super Contributor
timestamp: October 07, 2021, 03:45:10 pm
content: A 20MHz scope is fine for debugging this. If the SR is clocked at 16MHz, the maximum output frequency is 8MHz.
Transistor  biasing Alinco DX-SR8 - Page 1
Forum section: electronics / repair

author: mkube396
author_rank: Regular Contributor
timestamp: March 12, 2021, 03:25:35 pm
content: I have 2 bad final output transistors in my Alinco DX-SR8T I ordered 2 new RD100HHF1CI'm reading up on how to bias this MOSFETS and I'm a bit confused on where to get the current reading? do I just take it from the overall current the radio is taking from the power supply? so lets say the radio is drawing .8 amps I just bring it up to 1.6amps?on page 38.http://dw.hampedia.net:8090/downloads/alinco/hampedia.net.dx-sr8t_Service_manual.pdf
Transistor marking - Page 1
Forum section: electronics / repair

author: wn1fju
author_rank: Frequent Contributor
timestamp: August 15, 2021, 03:48:14 pm
content: Transistor is marked TS3011. I am interpreting the last two digits as a "European" one. Here in the USA, our ones are simply straight lines. The data sheet for a 2N3011 says "an NPN transistor designed for ultra-high speed saturated switching applications." The transistor is from an Adret (French) frequency synthesizer and this transistor is connected to a 74LS90 counter chip, so it makes sense that it needs to switch some high frequency stuff.But has anyone heard of a TS3011 and is a 2N3011 a suitable substitute?

author: wn1fju
author_rank: Frequent Contributor
timestamp: August 15, 2021, 10:09:09 pm
content: Oops - I found the manual. Even though the schematics show TS3011, the parts lists shows 2N2369 which are readily available. We will go with that.

author: amyk
author_rank: Super Contributor
timestamp: August 16, 2021, 03:43:43 am
content: Is that a 1964 datecode?

author: wn1fju
author_rank: Frequent Contributor
timestamp: August 16, 2021, 12:06:12 pm
content: "Is that a 1964 datecode?" Could be, but it looks like a Texas Instruments logo on the can, and I'm not an expert on when TI first started producing transistors.I've attached a snippet of the schematic, dated 1967. Have never seen a schematic with transistors drawn quite like that.

author: fzabkar
author_rank: Super Contributor
timestamp: August 16, 2021, 08:18:25 pm
content: Quote from: wn1fju on August 16, 2021, 12:06:12 pmhttps://mirrorservice.org/sites/www.bitsavers.org/components/ti/_dataBooks/

author: amyk
author_rank: Super Contributor
timestamp: August 17, 2021, 12:26:48 am
content: TI started making transistors in the 50s... and given your schematic shows a date of '67, a '64 datecode would certainly not be unusual. But looking at this page, the 3-digit "640" datecode may actually be 1966, 40th week:https://sites.google.com/site/transistorhistory/Home/us-semiconductor-manufacturers/ti
Technics SL1200 transistor replacement - Page 1
Forum section: electronics / repair

author: tohtorizorro
author_rank: Contributor
timestamp: November 13, 2023, 01:16:03 am
content: Hi!I'm servicing a Technics SL1200mk2 turntable and managed to create a short that burned two transistors from the voltage regulator circuit.I found two options with a matching pinout (collector in the middle) from my stash and would like to hear opinions on using them as replacements.Original transistors are 2SD637The available replacements are 2SC945 and 2SC1815I've added the schematic (see Q2 & Q3) and datasheets for the transistors.Thanks in advance,Mikko

author: BrokenYugo
author_rank: Super Contributor
timestamp: November 13, 2023, 02:49:03 pm
content: I'll hazard a guess any general purpose TO-92 NPN would do there, either suggested will probably work, I'd probably try the 1815.
Transistor with marking N61G 2D part number  - Page 1
Forum section: electronics / repair

author: vergrivit
author_rank: Newbie
timestamp: May 25, 2024, 08:05:37 pm
content: Hi everyone,Please help me find the part number for a transistor with the marking N61G 2D.

author: fzabkar
author_rank: Super Contributor
timestamp: May 25, 2024, 08:26:47 pm
content: Could it be a DDTD123EC digital NPN transistor?https://www.diodes.com/assets/Datasheets/ds30384.pdf

author: vergrivit
author_rank: Newbie
timestamp: May 25, 2024, 09:11:41 pm
content: not sure, the date code doesn't match the one specified in the datasheet, and it's also unclear what the letter G after N61 means.Anyway, thank you.

author: fzabkar
author_rank: Super Contributor
timestamp: May 25, 2024, 10:06:37 pm
content: Is there a resistor in the base drive? Is it driven directly from digital logic? Does it test as a BJT or MOSFET?

author: floobydust
author_rank: Super Contributor
timestamp: May 26, 2024, 01:42:21 am
content: What package is this? I got close with SOT-23 but it looks smaller

author: vergrivit
author_rank: Newbie
timestamp: May 26, 2024, 11:35:29 am
content: SOT-23

author: vergrivit
author_rank: Newbie
timestamp: May 26, 2024, 11:43:46 am
content: yes

author: fzabkar
author_rank: Super Contributor
timestamp: May 26, 2024, 05:42:34 pm
content: C255 = SN74LVC1G125 - Single Bus Buffer Gate With 3-State Outputshttps://www.ti.com/lit/ds/symlink/sn74lvc1g125.pdf01C = 10K resistorThe base of the transistor is driven from the output of the logic gate via a 10K resistor, so this would suggest that the transistor is not a digital one. A diode test should confirm this.

author: floobydust
author_rank: Super Contributor
timestamp: May 27, 2024, 01:18:06 am
content: Closest I can get isDMN6140LN-ch mosfet SOT-23 60V 1.6A marking code N61. LQ part is AEC qualified.The "G" must be a variant of it, I don't think it is second-sourced.
Treadmill EMI power filter repair or replacement - Page 1
Forum section: electronics / repair

author: Otomaru
author_rank: Contributor
timestamp: November 17, 2021, 10:37:25 am
content: Hello!A relative asked me to take a look at their malfunctioning treadmill and I've found the power EMI filter to have intermittent continuity through neutral line.The problem starts with finding a replacement. As I understand, EMI filters are tailored for specific loads and sources (balancing). I can't find an exact replacement, and I don't know how to determine if others are suitable.EMI filterAlso, there in a large inductor (ACL-4.6mH-8A 250mm) on live line between the filter and PCB.Maybe some one knows where you can purchase replacement filter?I opened the faulty one to take a look, but it's of course potted. Are there reasonable ways to fix it?Can I use different filter? Which filter? With or without the in series inductor?How safe is it to use the treadmill without the filter? Should I remove the inductor if I remove the filter too?Sorry, this is just beyond me. Please help.

author: wraper
author_rank: Unknown
timestamp: November 17, 2021, 10:59:03 am
content: Chose one which has suitable size and terminalsOr check Lemona, Argus, Salvats. You can also order from TME thru them, might be cheaper than paying for shipping.

author: Otomaru
author_rank: Contributor
timestamp: November 17, 2021, 11:12:06 am
content: Quote from: wraper on November 17, 2021, 10:59:03 amBut what about all the passive element values? Are those really irrelevant?

author: wraper
author_rank: Unknown
timestamp: November 17, 2021, 11:26:22 am
content: Any filter will work, it will work even without any filter at all. The question is only how well it will filter the interference. I specially selected in parameters 2 pole filter as the original one. I doubt that original designers even considered the internal values of the components, They just chose one which will do the job.
Triac damage - Page 1
Forum section: electronics / repair

author: Turbochardged
author_rank: Contributor
timestamp: June 12, 2025, 02:20:07 pm
content: I have a Ac unit with a "T405-600B" TRIAC 600V 4A DPAK turning on a 24v AC 24 watt reversing solenoid. The board and solenoid were replaced multiple times. I found that the Triac keeps failing. I was thinking of soldering on a bidirectional TSV diode on the board to absorb the flyback from the solenoid turning off. Just wondering what TSV sounds appropriate or should i look into other components.

author: Grandchuck
author_rank: Super Contributor
timestamp: June 12, 2025, 03:19:35 pm
content: RC snubber?https://www.st.com/resource/en/application_note/cd00004096-rc-snubber-circuit-design-for-triacs-stmicroelectronics.pdf
Triac testing and replacement for a washing machine - Page 1
Forum section: electronics / repair

author: ebourg
author_rank: Contributor
timestamp: April 02, 2024, 02:27:16 pm
content: Hi,I'm trying to repair an old Thomson Australe 2 washing machine that turns on but the programs don't start. The troubleshooting guide has a procedure to display the last error detected by the controller, and it points to a shorted triac driving the motor.The board looks good, with no burned or cracked component. The triac is mounted on a heatsink, it's a ST BTB15 600BCE. I've tested it in circuit and there is 52mV drop and 42 Ohm between A1 and G. A1-A2 and A2-G are open, with a > 1M Ohm resistance.[ Attachment Invalid Or Does Not Exist ]Is this enough to confirm that the triac is indeed bad?I searched on the ST site and this reference no longer exists, there is adatasheetarchived but it doesn't mention the BCE variant. The closest match seems to be the BTB16 which is rated for 16A instead of 15A. However for 600V there are several variants (SWRG, CWRG, BWRG, BRG, CRG) and I don't know which one to pick (if that matters in this case).

author: m k
author_rank: Super Contributor
timestamp: April 10, 2024, 07:55:08 pm
content: Replace with one with higher values is a normal route, except sensitivity of course.Same series usually have others.Problem appears when next one is mechanically too big.

author: Ian.M
author_rank: Super Contributor
timestamp: April 10, 2024, 08:08:21 pm
content: Quote from: ebourg on April 02, 2024, 02:27:16 pmOn the contrary, those readings indicate the TRIAC is probably good. If it was bad it would either be blown open, typically with highly visible damage, or shorted A1-A2.Look elsewhere for the fault. If you cant find one, we can talk you through testing the TRIAC out of circuit. . .

author: floobydust
author_rank: Super Contributor
timestamp: April 10, 2024, 11:11:51 pm
content: I've found a few triacs do have an internal resistor from Gate-MT1, around 50-100 ohms (I think it's for a better dV/dt spec).The resistance is not shown on the datasheet and my surprise when the new part reads that, same as the old part.Are you sure this switches the main motor? There are relays on the control board pics that I can see, I would suspect them.

author: ebourg
author_rank: Contributor
timestamp: April 11, 2024, 05:18:56 pm
content: Thank you, I'll leave that triac alone thenI've probably misinterpreted the diagnostic, I'm leaning toward a failure of the door lock which must be locked before the motor starts.

author: modoran
author_rank: Regular Contributor
timestamp: April 14, 2024, 06:48:04 am
content: Usually triacs are used for the heater in washing machines and 2 relays for the motor, one for each direction. Of couse, this is not always the case.
Tried fixig hp pavilion chiclet keyboard, incessantly types a key by itself - Page 1
Forum section: electronics / repair

author: marhuum
author_rank: Contributor
timestamp: July 07, 2023, 11:41:23 pm
content: How to fix hp pavilion chiclet keyboard, incessantly types by itself a key, only few seconds idleThe key is nThis'd be only in some PC startup times, on some startups else it doesn't, like typing this now, but still it'd last only ~15 minutes or ~150 key stroke before being defectedRather baffling, for sure in any condition, this N key itself doesn't function, hitting it won't register plain n into input bufferThese "n"s typed here is performed by way of remapped n key to another

author: thm_w
author_rank: Super Contributor
timestamp: July 08, 2023, 12:02:54 am
content: - Clean out the the 'n' key if its possible, it may not be possible as this seems to be somewhat sealed membrane kb, you haven't posted the specific model though- Probably not it but can try reseating and cleaning the ribbon connector for the keyboard- Use an external keyboard- or Buy a replacement keyboard for $20-30https://www.ifixit.com/Device/HP_Pavilion
Trimble 57963 board repair help needed - Page 1
Forum section: electronics / repair

author: WPXS472
author_rank: Regular Contributor
timestamp: May 19, 2020, 08:42:08 pm
content: I wasn't sure where to post this. I found references to this board in several places. But, since I am attempting to repair it, this is where I chose to put it. Sorry if this isn't the right place.OK, so I bought this off eBay back in April and it just arrived yesterday. Since these are prone to come with components missing, or damaged, I took a look under a microscope. I found L4 missing, what I assume to be R68 missing. It is right under C76. If someone could either send a close up photo of L4, or else describe it, that would help. Also, if someone could measure R48 that would be nice as well. In addition to these, U18 has taken a blow and is cracked. I am looking at sources for the OPA374. I will probably order it from Mouser. So far, I have found a good bit of information on this unit here. It was sold as guaranteed working. The seller's definition of working might be different to mine, but missing and broken components seem to indicate that it probably isn't working correctly. I see no point in powering it up until the missing and damaged components have been replaced.

author: WPXS472
author_rank: Regular Contributor
timestamp: May 21, 2020, 04:19:46 pm
content: It seems I was mistaken about R48. The missing component is actually L11. I misread the silk screen. I ordered another, hopefully it will actually have the correct components. And, I will have a spare.

author: WPXS472
author_rank: Regular Contributor
timestamp: June 16, 2020, 02:42:08 pm
content: If anyone else has this same issue, I took another one of these to my former employer yesterday and found that L4, L11 are 2.7 uH. I got replacements and will install them as well as the op amp today. SOmething tells me though, that this will not fix this problem.

author: WPXS472
author_rank: Regular Contributor
timestamp: June 29, 2020, 07:14:05 pm
content: Well, it seems that replacing the missing and damaged components did repair the unit. I didn't think so for a while, but it finally settled down fairly well. Not the best GPSDO I have seen, but not too bad.
Trimmer Caps thin plastic film cover - Page 1
Forum section: electronics / repair

author: todorp
author_rank: Regular Contributor
timestamp: December 23, 2020, 09:13:16 am
content: Hello all, I was changing the compensation trimmer cap in an oscilloscope probe. The replacement I am using is Murata TZB4Z060BB10R00 (https://www.digikey.it/product-detail/en/murata-electronics-north-america/TZB4Z060BB10R00/490-11907-1-ND/2604957).The Murata trimmer cap seems to have a very thing plastic sheet covering the whole top part of the component which prevents the insertion of the trimming tool. Is this normal/standard on trimming caps? Does one have to remove this plastic in some way and if yes than how do you remove it?Thanks a lot,Tod

author: shakalnokturn
author_rank: Super Contributor
timestamp: December 23, 2020, 09:57:17 am
content: I've noticed remains of plastic film on mounted SMD trim caps before, the Murata datasheet for yours says it's a protective coating for bath soldering .If there's no easy way to peel it and it's not designed to shrivel away to the edges when heated just pierce through it.Is the voltage rating on that trimmer sufficient for the application?

author: todorp
author_rank: Regular Contributor
timestamp: December 23, 2020, 10:15:11 am
content: @shakalnokturn thanks for the answer, I had not managed to remove it so just as you suggest I will pierce through it. The rating of the trimmer is 100V and is sufficient for the projects I have been doing: I am measuring only low voltages (max 30V). Than again the trimmer forms a 10:1 voltage divider so there shouldn't be any problems right?!
Trimmer screwdrivers that actually fit... - Page 1
Forum section: electronics / repair

author: rabidelephant
author_rank: Newbie
timestamp: April 19, 2023, 03:20:43 pm
content: Hello!I've acquired a bunch of trimmer screwdrivers over the years but none are fitting the trimmers I have on a new design and I've got tons of trimming to make on many units. I need the trimmer to have the cylindrical ring surrounding the flat head, as most do, but something that fits the adjustor properly so I'm not aimlessly spinning, wiggling or having to look to line it up. I have the Bourns H-90, which they say fits their 1/4" trimmers and these have the same diameter adjustor as on the BI part I use, but it still doesn't seem to be fast in engaging. I think the inner diameter of the 'ring' is too big. I'd not care so much but I really have many 1000s of adjustments to make and would like to get a nice tool for the job.Does anybody know of a trimmer screwdriver that will fit these 1/4" trimmers?https://www.mouser.com/datasheet/2/414/TTRB_S_A0009734243_1-2565577.pdfLMK!

author: RoGeorge
author_rank: Super Contributor
timestamp: April 19, 2023, 03:27:07 pm
content: I've took an iron nail (for wood planks) and filed its tip. A wine cork, or an empty ballpen, or toothpaste caps can make an isolated handle. Have a few made entirely from hard plastic, no iron, good for tuning ferrite coils .

author: rabidelephant
author_rank: Newbie
timestamp: April 19, 2023, 05:38:56 pm
content: Yea, making one is probably my only bet, it seems. The issue with the drivers I am having is they don't really make the ID of the cylindrical centering ring close enough to the OD of the adjustor and so mating is finicky.

author: KevinA
author_rank: Regular Contributor
timestamp: April 19, 2023, 08:47:49 pm
content: Vishay 008T290 made especially for these.Available from RS, part number 852-4614Also Bourns H-90. RS part number 743-2479 (half the price)Kevin

author: Swake
author_rank: Frequent Contributor
timestamp: April 22, 2023, 06:18:55 pm
content: Take a screwdriver that fits but is slightly larger than the screw. Put some heat-shrink around the round part above the blade. A centimeter is long enough, the idea is that after it shrunk you can push it down over the blade so that it forms the guide you want.
Trio CS-1560A Oscilloscope - Voltage Selector Plug - Page 1
Forum section: electronics / repair

author: austfox
author_rank: Regular Contributor
timestamp: February 04, 2020, 02:29:11 pm
content: I've recently acquired a Trio CS-1560A scope which is missing the voltage selector plug. This is used to select the mains input voltage.Does anyone have one of these Trio scopes that use these plugs (I understand a few different models shared this design). I just want to confirm that the pins I will be bridging will be correct for 240V operation, as per the attached photo.Thanks.

author: Haenk
author_rank: Super Contributor
timestamp: February 05, 2020, 05:02:38 pm
content: This seems to be the same selector type, found in a different type of equipent I slaughtered (Japan, about 1985).I have no idea, if the plug is generic or individual to the unit, so the diagram might be OK - or not. I assume it's generic...The plug is shown with the arrow pointing upwards (and from the back, of course).Hope this helps, at least it matches your drawing (upper left is nc on my connector as well…)

author: austfox
author_rank: Regular Contributor
timestamp: February 06, 2020, 04:03:01 am
content: Many thanks for that.From your pictures it looks like I traced it correctly. I’ll bridge those pins and do a final ohm reading through the primary side before I apply power.