hybridfree/eevblog-posts huggingface dataset:
Trio TS-120s Transceiver help needed please! - Page 1
Forum section: electronics / repair

author: christopher iles
author_rank: Regular Contributor
timestamp: May 05, 2020, 10:56:13 am
content: Hello,My Trio TS-120s won't receive. Here's what I've checked so far.Carrier oscillator is working.Display is reading normal.Finger test on the volume pot shows the audio amp is working.500KHz is present.10MHz is present.There is an output on the rf pcb (RIF).However,The radio is dead, no white noise (unless I pull the J29 connector on the IF board, then there is noise).The "s" meter does not move.I've checked the band switch and wafers, they're ok.I've tried all bands, nothing.The radio is not in transmit condition.I'm at a loss now, from my tests, the radio should be receiving!One thing to add; if I go to transmit with no microphone connected the radio puts full power out as if it's on CW with the key down. I don't know if this may be significant.Any help would be greatly appreciated as I really don't want to scrap the radio for parts.Very 73,Chris, G0VOE.

author: coromonadalix
author_rank: Super Contributor
timestamp: May 05, 2020, 11:35:50 pm
content: serice manual if neededhttps://w5rkl.com/wp-content/uploads/2015/02/TS120S_serv.pdfhttps://www.manualslib.com/manual/891848/Kenwood-Ts-120s.htmlhttp://hammadeparts.jivetones.com/Amateur_Radio_Manuals_Schematics/KENWOOD/TS-120S_serv.pdfhttps://mafiadoc.com/kenwood-ts-120s-service-manual_59c3362c1723ddd8d9666ef2.htmlThe first thing i would say is to check all supply lines ... the tx and rx switching
Tripp Lite SmartPro UPS Schematics Available?  - Page 1
Forum section: electronics / repair

author: Mikek400
author_rank: Regular Contributor
timestamp: October 27, 2021, 01:03:43 pm
content: I was wondering if anyone knows if the schematics are available anywhere out there for the Tripp Lite SmartPro or other similar Tripp Lite units?I have a Tripp Lite SmartPro 3000 I was looking at possibly modifying it and a schematic would be great.I know the APC SmartUPS schematics are out there and those have helped a ton with troubleshooting and modifying them.Anyhow, if anyone has or knows where to find these please let me know. Thanks!
Trompeter ADBJ20-E1-PL75 and Keithley 7078-trx-bnc - Page 1
Forum section: electronics / repair

author: hitecelec
author_rank: Regular Contributor
timestamp: April 19, 2024, 05:48:09 am
content: HiI am not able to find the voltage and current specs as mentioned in Keithley 7078-trx-bnc for Trompeter equivalent AFBJ20-E1-PL75datasheet attachedis there a significant difference, what are the trade offs as the trompeter is half the cost of keithleyThanks in AdvanceAnand

author: alm
author_rank: Super Contributor
timestamp: April 20, 2024, 10:41:00 am
content: I can't find any electrical or material specs either, but I found one of each in my adapter tray, and it looks to me like the insulation on the Trompeter in the triax connector is much thinner. So I could imagine it having a lower resistance rating between inner shield and outer shield (which isn't even specified on either). The Keithley connector looks a bit better made mechanically to me due to the extra insulation, but I'm not sure if that would be worth the price premium to me. See attached pics (Keithley on the left, Trompeter on the right).If you want me to do any measurements, PM me in two weeks or so.

author: hitecelec
author_rank: Regular Contributor
timestamp: April 22, 2024, 07:03:30 am
content: helloThanks for the prompt response.Your feedback is highly appreciated.Will be intouch if I need any helpregardsAnand
Trotec IC080 LV Thermal Imaging Camera - Strange Issue - Page 1
Forum section: electronics / repair

author: duckmansweb
author_rank: Newbie
timestamp: November 08, 2022, 11:23:40 pm
content: Hi guys, im thinking of buying a faulty Trotec IC080 LV - Camera is stuck in a boot loop with a coloured screen and garbled words (see attached) seller says he cannot fix it and has also tried another firmware file, would anyone know what the issue could be - or has had any experience with these thermal cameras ?
Trouble identifying 10k? capacitor - Page 1
Forum section: electronics / repair

author: nsummy
author_rank: Contributor
timestamp: May 06, 2024, 09:19:56 pm
content: I am repairing an old Eico 324 Signal generator. I'm not sure if this was built as a kit or has had other repair work done in the past but looks original. I am replacing the paper caps and there are 3 .01 uF caps. The schematic/parts list makes no distinction between them (all same part number) but I am growing confused when reading about safety caps, which I am not very familiar with. Anyway, long story short, all 3 of these capacitors currently in the circuit are different. The 2 caps connected to the mains look similar but one says 10k on it, and I'm confused whether that means something or not. please see attached pics for an idea. Thanks

author: wasedadoc
author_rank: Super Contributor
timestamp: May 06, 2024, 09:41:31 pm
content: 10k is 10,000pF which is 10nF which is 0.01uF.

author: floobydust
author_rank: Super Contributor
timestamp: May 06, 2024, 09:51:30 pm
content: Do note that is also called the "death capacitor". C1, C2 need to be Y-capacitors with appropriate safety ratings because their failure makes a shock hazard. You can see discussion of them as they were commonly used in tube guitar amplifiers. They are on the big side at 10nF, I'd have to calc. the leakage current if it's enough to bite.I would consider changing over to a 3-wire grounded line cord and adding a primary-side fuse.

author: nsummy
author_rank: Contributor
timestamp: May 07, 2024, 02:19:14 pm
content: thank you, I feel like an idiot now haha

author: nsummy
author_rank: Contributor
timestamp: May 07, 2024, 02:20:00 pm
content: Quote from: floobydust on May 06, 2024, 09:51:30 pmThank you, definitely replacing them with Y caps!

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: May 07, 2024, 08:35:25 pm
content: I am with Flooby.If you plan on using the unit a lot, consider just putting in an EMI filter. They contain the Y caps and an X cap and then you have a modern 3 pronged plug, you probably need a new cord anyway.Lots more EMI today then when these things were made.
Trouble to identify smd tantulum from gpu - Page 1
Forum section: electronics / repair

author: Robertkopp
author_rank: Newbie
timestamp: September 11, 2021, 09:59:36 pm
content: Hey buddies,I have trouble to figure out what style of code that is and thus the voltage of this capacitor is. I mean d=20V can not be right under a gtx660ti gpu die or am I mistaken?

author: mariush
author_rank: Super Contributor
timestamp: September 11, 2021, 10:24:10 pm
content: The video card's input power is 12v and 3.3vThe gpu runs at 1..2v , the ram runs at 1v...1.6v so the capacitors on the output of the VRMs can be rated for 2v or even less.See for example Panasonic catalogue, go to page 13:https://industrial.panasonic.com/cdbs/www-data/pdf/ABE0000/ABE0000COL61.pdfThey use d= 2.0 , e = 2.5 , g = 4.0 , j = 6.3 , A = 10 , C = 16 , D = 20 , E = 25 , V = 35So it's probably a 470uF 2v polymer capacitor. It's not tantalum... pure tantalum, it could have some tantalum in it but I doubt it.Seehttps://na.industrial.panasonic.com/products/capacitors/polymer-capacitors/lineup/sp-cap-polymer-aluminum

author: Robertkopp
author_rank: Newbie
timestamp: September 11, 2021, 10:33:49 pm
content: Thanks for the quick and in depth reply.
Trouble with Flash Memory: Seeking Advice for S29GL256P11TFIV2 - Page 1
Forum section: electronics / repair

author: shawki fekri
author_rank: Newbie
timestamp: February 01, 2024, 07:09:23 am
content: Description:Hello everyone,I'm encountering some difficulties with the S29GL256P11TFIV2 Flash memory device, and I could really use some guidance on how to proceed. Here's a summary of my issue:Problem:I have been trying to read data from the S29GL256P11TFIV2 Flash memory device using a compatible programmer (RT809H), but I'm experiencing problems with data corruption. Despite successfully reading the data once, subsequent attempts result in corrupted data, and the device no longer starts up properly.Steps Taken:Checked hardware connections to ensure they are secure and properly aligned.Verified compatibility of the programmer (RT809H) with the S29GL256P11TFIV2 Flash memory device.Followed standard read procedures, but encountered data corruption issues.Additional Information:The Flash memory device was previously working without issues before attempting to read data.I've tried different read settings and parameters, but the problem persists.I'm concerned that the device may have been corrupted during the reading process, and I'm unsure how to proceed to recover the data or restore the device to its original state.Request for Assistance:I'm reaching out to the community for any insights, suggestions, or troubleshooting steps that could help me address this issue. If anyone has experience with the S29GL256P11TFIV2 Flash memory device or similar problems, I would greatly appreciate your assistance in resolving this issue.Thank you in advance for your help and guidance.

author: Bud
author_rank: Super Contributor
timestamp: February 02, 2024, 05:52:28 pm
content: You said you successfully read it the first time. Why dont you erase it and re-program.

author: fzabkar
author_rank: Super Contributor
timestamp: February 02, 2024, 09:06:23 pm
content: Could you upload your first dump and a few recent dumps? I would like to compare them with a hex editor to see what is happening.Also, there may be a checksum that helps to verify the integrity of your dumps.BTW, how do you know that your first dump was good? IMHO, it would be unwise to erase and reprogram your device until you are absolutely certain that the dump is OK and that your programmer is fully functional and compatible.Datasheet:https://www.mouser.com/datasheet/2/196/Infineon_S29GL01GP_S29GL512P_S29GL256P_S29GL128P_1-3363530.pdf

author: JimKnopf
author_rank: Frequent Contributor
timestamp: February 03, 2024, 08:31:12 am
content: @shawki fekri Can you provide screenshots with the settings you used to read the dumps? Any log file?
Troubleshoot Flow Chart PM2525 (Calibration isuue) - Page 1
Forum section: electronics / repair

author: watchmaker
author_rank: Unknown
timestamp: August 04, 2025, 11:59:42 am
content: I have an Artek manual I am using to calibrate a PM2525. I perform the manual calibration per pg 5-15 and get to the calibration received message (success). When I reset the display still shows "NC" (not calibrated) for that scale.I have used a new b/u battery. I also have a second meter with a bad display. I exchanged all socket mounted chips one by one. No joy.Wash and repeat.My Artek manual seems to have intentionally left out the trouble shooting section.Does anyone have a complete SM for this PM2525?

author: Swake
author_rank: Frequent Contributor
timestamp: August 06, 2025, 08:48:57 am
content: Philips/Fluke does not provide detailed troubleshooting information as HP did. Troubleshooting is like 1 page. No schematic either.

author: watchmaker
author_rank: Unknown
timestamp: August 07, 2025, 01:13:51 pm
content: Thanks. Your SM is more complete than mine, but it still is not helpful for determining why calibration does not hold after I get the ready display, rest and apply the same voltage.The battery is good and has also been replaced. I follow the manual calibration process shown on pg 5-18.
Troubleshooting a boost converter based on TPS4021 - Page 1
Forum section: electronics / repair

author: Yamin
author_rank: Frequent Contributor
timestamp: July 31, 2022, 10:57:35 pm
content: Hi guys,I'm working on an Allen & Heath qu16 digital audio mixer. The main issue was that the 48V phantom power needed for the condenser mics were very low. With no mic it measured around 26V and it went down as more mics were plugged in. Also there was sound of chirping coming from the I/O board.Opened the unit and here is what I found out. The 48V is derived like this.8V(coming from the main PS) --->+12V--->+53V--->Regulated 48V.The 12V rail and 53V rail is made from TPS4021. When the unit is powered up the 12V output never reaches 12V it jumps around (sort of restarts) and settles around 5ishV, So the 53V doesn't reach 53V and nor does the 48V output. The 8V input voltage coming from the main PS remains stable.The circuitry for 12V,53V looks very similar apart from few obvious change in component values.From what I can deduce the problem is coming from the 12V output, and here is an something odd which I discovered. At the 12V (FB,Comp Pins) circuitry when I measured the resistance across R88 the value kept on increasing (the same as what happens when you see a capacitor charging). I didn't see this when I took the same measurement from the 53V side. So thinking that the resistor might have gone open or something I took it out of circuit and measured it. It showed dead on 47Kohms. I measured all the other components around there and noted the values. I still see the same sort of measurement when measuring across the open pads of where the resistor was.I was hoping that I could get further tips on what to look for. I have a feeling that the TPS4021 IC maybe faulty but how can I confirm this? I have measured the outputs for shorts but didn't measure any.Thanks in advance.P.S I couldn't find how feedback resistors values are calculated to get the needed output voltage.

author: fzabkar
author_rank: Super Contributor
timestamp: August 01, 2022, 12:23:42 am
content: The feedback voltage for the TPS40210 is 700mV.Vout = (5.6K + 47K + 3.2K) / 3.2K x 700mV = 12.2Vhttps://www.ti.com/lit/gpn/tps40210
Troubleshooting a Mini-split AC Inverter  - Page 1
Forum section: electronics / repair

author: natiz
author_rank: Newbie
timestamp: July 27, 2019, 09:41:02 pm
content: Hi,I have a mini-split inverter AC (a WIND INV40A by Tadiran) which stopped cooling a few years ago, and its time I get it fixed.When the AC starts, the fan starts turning on the outside unit, but then stops after a few seconds. The compressor never kicks in.The indoor unit then outlines error 06, and the main board (as can be seen in this video) has the led blinking 12 times, indicating E12 which according to thedistributor (and google translate)is:QuoteI know my way around a multimeter and I was wondering if I can try finding what the actual issue is before replacing it completely (a new IPM costs more than a new AC for some reason :\)What do you guys suggest I check?Attached a wiring diagram by the distributor and a pic of the outside unit boards.

author: soldar
author_rank: Super Contributor
timestamp: July 28, 2019, 09:04:10 am
content: I have had some similar experiences. Unless you have a lot of free time and nothing better to spend it on my guess is that chances are you will waste much time and not get far. From a practical point of view I would suggest finding a pro.Now, assuming you have time and do not mind wasting it, you need to understand the controller board is not just some basic electronics but a programmed controller.When it starts up it goes through a routine of checking parameters here and there, waiting for this and that, and it will usually take several minutes before it even tries to start up the compressor. Troubleshooting the board without having complete documentation will be very difficult. You can try all the sensors and other inputs. You might get lucky and find something easy and obvious. Go over all the wiring, connections, etc and make sure everything is as it should be.I had a unit fail under warranty a couple years ago and the guy came out and replaced both boards (inside and out). He told me the boards are not worth repairing as he, with all his knowledge, could spend hours on each board and only be able to repair a small fraction of them. Not worth it.A different issue which happens often is refrigerant loss. If the system is not absolutely tight then it might lose some refrigerant. Especially some of the newer refrigerants work at higher pressures and will leak more easily. A pro has the tools and knowledge that he can check this in a matter of minutes and it is not something that it is worth your time or effort.
Troubleshooting A/C fan motor - Page 1
Forum section: electronics / repair

author: soldar
author_rank: Super Contributor
timestamp: June 16, 2024, 09:16:46 pm
content: A friend asked for my help in troubleshooting a problem with the fan of the motor of the evaporator of a split A/C system. He is in another town so I do not have access to the system myself.He says the motor will not start and the system detects no rotation and will stop and give an error code. He says if he helps it start then it will rotate and work OK. Mechanically the motor shaft rotates completely freely. No mechanical resistance.He thought it might be the motor so he bought a replacement but the problem persists. Once the motor starts rotating it works fine so he pushes it a bit to help it start and later just keeps the AC running so he raises the setpoint so the compressor is not working but the fan keeps running. For now he gets by like that.He sends me the attached photo of the motor which has a schematic of the connections.It has two connectors with three cables each. The main connector has Red and Black wires which are the main for power supply and a white for the capacitor. I suggested the capacitor on the main board might be bad but here is where things beging to get strange because connecting the motor to the board produces the problem I described: it does not start. But if he connects 230 V directly from mains to red and black then the motor starts and runs fine. With no external capacitor.Question the first: Is it possible the capacitor is inside the motor housing? Included with the motor? Seems like this would explain why the motor starts fine. But if the capacitor is included with the motor why the need for the white wire to go to the control board?Also, I do not understand the purpose of the other three wires but I suspect they are a speed sensor reporting back to the control board. But why that capacitor in the schematic? Anyone know more about this motor?And how is the motor speed controlled? Just a resistor inserted in series? Because there is only one winding, no taps.If I had access I would try to measure voltages, waveforms, etc. but, as I say, I am far away and cannot do this.What do you think? Any suggestions or advice?Edit: The three white wires on the right are the Feedback Generator and they are Gnd, Vcc and Output. I think it is safe to assume that part is working OK. My inclination is to suspect the motor is receiving insufficient voltage between Red and Black.

author: indeterminate
author_rank: Regular Contributor
timestamp: June 17, 2024, 03:28:56 am
content: Replace the capacitor, it is there to start the motor.Motors can start but unreliably with no cap & no load.https://en.wikipedia.org/wiki/Induction_motor
Troubleshooting and repairing no-power issue on Yamaha TSR-7850 A/V Receiver - Page 1
Forum section: electronics / repair

author: Drnict63
author_rank: Newbie
timestamp: June 30, 2021, 03:11:17 pm
content: Greetings! Longtime EEVBlogs subscriber, but new to the forums.I snagged a Yamaha TSR-7850 for a good deal, knowing it had power issues. When I plug the amp into power, I hear some caps charge up, but it does not have any lights and doesn't make any noises or signs of trying to turn on with any button combinations I've found online so far, so I'm thinking we're looking at either a totally bricked amp or a hardware issue.I'm not sure where to start, so I watched a few videos of others troubleshooting their yamaha receivers, couldn't find anything on the exact same model but I took some measurements of what seems like a common connector to start with; coming from the power supply to the main board (see photo for multimeter results with amp plugged into power)Any tips on where I should start? Any new button combinations I should try on this model?Thank you!

author: esepecesito
author_rank: Regular Contributor
timestamp: June 30, 2021, 04:50:50 pm
content: Wow "I hear some caps charge up" how do you hear it? I'm not sure what do you mean with that.I would start by measuring the output of the transformer, then after rectifier, then after regulator.

author: Drnict63
author_rank: Newbie
timestamp: June 30, 2021, 05:52:34 pm
content: Sorry, I am probably causing more confusion just mentioning it, I just mean I can hear it getting juice when I plug in the mains. I can often hear electronics quickly "charge up" when being plugged in similar to how displosable cameras sound when charging their flash.Will need to figure out how I test what you've mentioned and report back. Thank you
[Solved] Troubleshooting select EEPROM configuration! - Page 1
Forum section: electronics / repair

author: AkibUddin
author_rank: Contributor
timestamp: December 02, 2022, 03:03:14 pm
content: Richmeter RM219 has P24C02A eeprom, so if i use 24c02 eeprom then have any problem ? P24C02A bidirectional data transfer speed 1mhz & 400khz other side 24c02 eeprom has 400khz & 100khz ..

author: coromonadalix
author_rank: Super Contributor
timestamp: December 02, 2022, 04:10:03 pm
content: your thread is confusing and i would say not indicativeare you talking about eeprom wear and tear, read and write cycles, life expectancy before failures, data corruption ?

author: wraper
author_rank: Unknown
timestamp: December 02, 2022, 04:18:36 pm
content: Both are "24C02" which is a generalization. Second one not being specific about what it actually is, there are a ton of different 24C02. Generally all 24C02 are mostly compatible but there may be differences which can be an issue in some cases. The issues may be with operating voltage range, presence of adress pins (if not all of them are connected to GND), maximum clock frequency if a high clock speed is used in particular device. Also they may have different maximum page write size. Generally all of that is not an issue, however device may be deing something out of particular IC spec.As of max I2C speed, it's very unlikely this meter uses over 400kHz.

author: AkibUddin
author_rank: Contributor
timestamp: December 04, 2022, 12:53:18 am
content: Quote from: coromonadalix on December 02, 2022, 04:10:03 pmconfusing about eeprom selection when original get corrupted

author: AkibUddin
author_rank: Contributor
timestamp: December 04, 2022, 12:57:09 am
content: Quote from: wraper on December 02, 2022, 04:18:36 pmYou got the issue

author: AkibUddin
author_rank: Contributor
timestamp: December 09, 2022, 02:12:06 am
content: Here still using 2 different type eeprom in same multimeter24c02a has 1M to 400k Other hand 24c02n has 400k to 100K bidirectional data transfer speed. Booth still working  Aneng M118A

author: wraper
author_rank: Unknown
timestamp: December 09, 2022, 01:57:21 pm
content: Nope, all of them have speed range starting from basically 0 Hz. Initial I2C standard allowed maximum of 100kHz, later standards increased it to 400kHz and 1MHz. Mentioning higher clock figures means that chip adheres to later standard.
Troubleshooting home theater PSU - Page 1
Forum section: electronics / repair

author: bitwelder
author_rank: Super Contributor
timestamp: January 26, 2020, 06:28:35 pm
content: Hello,after many years of faultless service, a couple of weeks ago my home theater system (a Philips HTS 3270) suddenly went silent (in the middle of a bigclive video)It's usually connected to the TV/Video system, but I tried to play a DVD so to have an internal audio source and it was the same.Even after setting the volume to max the speakers were completely silent, no hissing/buzzing noise.After looking at the service manual and the datasheet of the power amplifiers (TAS5342L) my guess was that the amps were probably held into shutdown mode.So, I checked the power supply board.Visual inspection: I don't see electrolytics that have bulged or leaked.On the PCB there are some brownish heat traces only near Q902 and IC902 (i.e. the two switching MOSFETs)Checking the voltages, I started to find some weirdness.According to the schematics (in attachment), there are 3 output connectors, 2 of them (bottom right corner) provide +5V, +12V, -27V and stand-by 5V, the other one (top right) has a thick connector to provide VCC (which oddly in some part of the manual should be 26V and in others 34V) for the power amps.Now, with the device turned on, these are the voltages I have measured:label -> measured+5V -> 5.25 V+12V -> 13.74 V-27V -> -29.55 VBK5V -> 5.25 V (i.e. stand-by voltage)VCC -> 26.01 VShould I be worried about the voltage differences from the ideal value?If so, considering that basically all voltages from the 'bottom' switching circuit are a little off, where should start to investigate? The primary section of T901 (i.e. the behavior of the TNY180) ?What else would you suggest to check?UPDATE: as I was writing this post using my notes from 2 weeks ago, after having left the unit unplugged and open, I reassembled it to verify the voltages, and while they are still similar, now playing a DVD *does* produce sound. But still I'd like to run a check-up of the unit, and avoid some possible permanent damages.

author: mzacharias
author_rank: Frequent Contributor
timestamp: January 27, 2020, 09:06:26 pm
content: I would say the voltages measured are within the normal range, BUT do not discount the possibility of noise on any given supply line.This can be checked with a scope.

author: bitwelder
author_rank: Super Contributor
timestamp: January 28, 2020, 08:35:44 am
content: Thanks!The main reason why I was a little worried about the voltages is that the +12V becomes the VDD for the power amps ICs TAS5342L, and in their datasheet the max value is 13.2 V.But I'll take a look with the scope
Troubleshooting HP 8903A Audio Analyzer input - Page 1
Forum section: electronics / repair

author: MWH901
author_rank: Newbie
timestamp: August 06, 2024, 06:36:00 pm
content: Hello... I'm working on an 8903A which is exhibiting odd behavior. Using an external signal generator and just exercising the input/analyzer functions, I have encountered a scenario where distortion increases and signal input voltages read incorrectly low, but only within a certain range, maybe ~3.5V - 12V.For example, using auto-ranging, a 5.0V 1kHz input signal will read 4.69V on the display at a THD of 6.41%.However, when use 1.7SPCL to force the unit into the 18.9V input range, that same 5.0V input signal reads properly as 5.0V and .02% distortion.I'm having a hell of time figuring out where/how that distortion is getting introduced within that particular range. I did look at the distorted waveform on the scope, and the bottoms of the sine wave seem a bit rounded off... maybe a sagging negative voltage rail somewhere?Thanks in advance...-Mike
Troubleshooting HV section of a Tektronix 7904 scope --- Help needed - Page 1
Forum section: electronics / repair

author: rodd
author_rank: Regular Contributor
timestamp: May 05, 2024, 03:43:02 pm
content: Dear all,I started trubleshhoting this scope and the symptom was a blurry trace.Than, after some time, I heard some clicking noises and the trace disppeared; there was just a faint glow on the CRT.I removed the HEPS and found a dead transistor in the regulator board (Q1451) which was part of the +15V rail.Then, I reconnected the HEPS to the scope with the HV section disconnected (one lead of R1606 and R1603 lifted) and checked the voltage rails in the Z axis board test points- all were spot on.However when I reconnected the HV section, the HEPS went to ticking mode, so I think there is a problem in the HV sectionSince it takes a lot of work to get to these boards, is there any other component that is prone to failure in the HV section?I have tested the two 22 meg resistors (in circuit) and they were fine.I intend to replace the diodes and capacitors in the autofocus (CR1653/1656/1655/1658 and C1654/1656) and in the HV regulation loop (CR1676/1679/1680/1682 and C1678/1680) as was suggested in other threads.Should I replace the HV diodes CR1607/1608 as well. If affirmative I wil use 2CL73A as replacements.I will use BY206GP (350V, 1A, 1uS recovery ) as replacements for the FDH5004. Is that adequate?Since it is not a Tektronix dedicated foram, I have attached the schematics for those who try to help me.HV section & CRT 070-2390-00.pdf(1503.66 kB - downloaded 45 times.)Thank you all.

author: BlownUpCapacitor
author_rank: Frequent Contributor
timestamp: May 05, 2024, 07:29:59 pm
content: The 7904 is notorious for tantalums being shorted. Check the resistances of the power rails.https://www.eevblog.com/forum/repair/tektronix-7904-repair/One of my previous threads has resistance of power rails so use that. Find a rail that has a low resistance. There is likely a bad tantalum on that rail.
Troubleshooting no audio output on a Philips mini hi-fi - Page 1
Forum section: electronics / repair

author: michalism
author_rank: Regular Contributor
timestamp: January 07, 2022, 10:17:20 am
content: Hello everyone and happy new year!I’m trying to figure out why this mini Hi-Fi system does not play sound. The model is MCM239D, and I am attaching some pages of the service manual (due to size limitations).Using a signal trace, I confirmed that there’s an audio signal on the input pins of the TFA, but I get nothing on it’s output.With the power on, I’m measuring 0V on pin7, instead of something much closer to Vcc. I checked the components associated with that line and they all check ok.Could this be a problem with the main microcontroler?If I’m not mistaken, according to the datasheet of the TFA and the service manual, the microprocessor is giving the signal to switch-on the TFA, correct? I think it’s the “MCU18 /STDBY” labels in the service manual (pages 6-1 and 8-1).Am I wrong so far? What else should I try?Some more notes:- I checked for shorts but I was not able to find any.- The TFA9842BJ is new, I replaced it to eliminate the possibilty of the IC being broken- Vcc is good.- Q804 ans Q801 also measure ok with the multimeter.- The input of Q801 is at 0.645V and that of Q804 at 0.976V (with respect to ground)- However, the output of both Q801 and Q801 is at 0V DC. Is this normal?- Diodes also check ok. I can’t check the zeners.- There are no bulged capacitors.- I can’t find R804 on the the pcb- The voltage at T12 (STDBY) is 2.4 V.Any suggestions?Thank you so much in advance!!Michalis
Troubleshooting of modified Palit 1070 GTX Dual problems  - Page 1
Forum section: electronics / repair

author: rob-bits
author_rank: Newbie
timestamp: February 22, 2021, 09:35:45 pm
content: I am a Mechactronical engineer and I would like to restore a modified card into original state. I would like to ask for some help in troubleshooting.Recently I bought a modified Palit GTX 1070 Dual videocard on eBay. Based on the item descriptions, two inductors were removed. One from the VRAM path and one from the PLL/PEX path. For VRAM voltage an AMPLE 20A Power Card is attached. The PLL has another power board for PEX voltage. I do not have much information about any further modifications. I found out a Mostfet is broken on the original 1.35V line so currently I cannot remove the AMPLE board until the replqcement has arrived. I set its output voltage to 1.35V. However I have removed the second external board from the PEX voltage and soldered back the missing inductor because that part of circuit seems ok.When I plug the card into PC and start the system it starts. The windows recognised the card, the driver starts without any issue but there are some instabilities. Sometimes there are some screen glitches and sometimes it is frozing out. If I start a rendering test, the rendering stops after 5-6 sec. By the way the GPU temperature is ~50°C. When I try to use the card I got the following issues:cuda error in CudaProgram.cu:465 an illegal memory access was encountered (700)GPU1 search error: an illegal memory accessunable to get fan speed - unknown error (999)The issues appears very randomly. Some come up after 30-40 sec. Some after 5 sec from start. Sometimes the windows crashes sometimes not.What shall I check? What can be the problem?Is the PEX voltage not sufficient?For next step I would like to check the signals with scope on the PLL voltage controller and controller of voltage regulator for VRAM to check their functionality.I am using Windows 10 with most recent Nvidia driver. The card has the EVGA GTX 1070 86.04.3B.00.3F bios (not original Palit bios)Any help would be welcomed. Thank you.
Troubleshooting the Makerhawk Load Tester - Page 1
Forum section: electronics / repair

author: samthelion17
author_rank: Newbie
timestamp: June 08, 2024, 09:31:52 am
content: I recently boughtthis deviceand it was supposedly "used_like_new" but it didn't work so I tried to return it. Long story short: they didn't want it back, gave me credit and I got to keep it, but now gotta fix it.It turns on but when I rotate the knobs it doesn't draw power from the load input(short video). When I removed the fan to check the power mosfet (IRFP264) I noticed a scorch mark near the schottky diodes (STPS41H100CG) and one contact pin of the nearby USB port missing.IDK what happened there... I turned on my meter, measured the diodes and the mosfet and I think they're all OK. I connected a laptop power supply and measured some voltages in that area and this is what I got:Some time later I measured the big SMD diode (SS56) next to the input screw terminals and found it to be faulty (dead short) so I replaced it but it didn't change anything.I'm waiting forthis power mosfetto arrive 'cause i'm not 100% sure if the one that it's currently installed is faulty or not but IDK what else to do or what else to look for.Thanks in advance!
Troubleshooting tips on 2200-series P/S - Page 1
Forum section: electronics / repair

author: pitpat
author_rank: Contributor
timestamp: February 25, 2021, 09:37:52 am
content: So, in the middle of the night i found this old guide buried in to the internet.I TAKE NO CREDITS for it and if the the owner will eventualy show up ill be pleased to remove this threadHope this will be as useful as it was for me!!
Troubleshooting what seems to be a germanium diode - Page 1
Forum section: electronics / repair

author: gkmaia
author_rank: Frequent Contributor
timestamp: December 31, 2019, 02:54:22 am
content: I got a bit stuck on this one and that is probably a stupid question... as I am implying it is a diode. But could be something else, I am not sure.The SG1 component seems to be open and not forwarding current in any direction on my curve tracer up to a 100V.It is part of the primary block (auto voltage) of a flyback power supply of a TDS 2002C.

author: amyk
author_rank: Super Contributor
timestamp: December 31, 2019, 03:15:39 am
content: More likely to be a zener for regulation. Trace the schematic out for the part of the circuit it sits in.

author: TheMG
author_rank: Frequent Contributor
timestamp: December 31, 2019, 03:32:46 am
content: That is NOT a diode, it's a spark gap, thus the "SG1" designation. Another common name for this is a GDT (gas discharge tube).It's there for surge suppression and won't conduct until there's a fairly high voltage across it (hundreds of volts).It is common to find these in various forms in the primary side EMI filtering circuit of SMPS. In low-cost SMPS they are usually in the form of pointy PCB traces but in better quality SMPS are a physical component which provides a more controlled spark-over voltage and are more durable. The modern version of discrete GDT usually use white ceramic as opposed to a diode-lookalike glass package.

author: coromonadalix
author_rank: Super Contributor
timestamp: December 31, 2019, 03:53:40 am
content: It is a spark gap device as TheMG wroteSevice manual, no schematicshttps://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=17&cad=rja&uact=8&ved=2ahUKEwikhM64_d7mAhXlhOAKHcixCRkQFjAQegQIBBAC&url=https%3A%2F%2Fdownload.tek.com%2Fmanual%2F077044600web.pdf&usg=AOvVaw0s9h1CGOKtt7Cm91EAQr-xpage 6-37 you have voltages tests points

author: SeanB
author_rank: Super Contributor
timestamp: December 31, 2019, 09:27:15 am
content: Spark gap, in this case basically a glass encapsulated carbon film resistor that has had a groove ground or laser cut all the way around the circumference of the resistive layer, so that it will arc over at a well defined voltage around the 2-300V mark. Only way to test them is with a current limited ( under 1mA) high voltage supply, to see if it does break down and clamp to that high voltage, but they rarely fail unless physically broken or corroded through.

author: Gyro
author_rank: Super Contributor
timestamp: January 04, 2020, 08:53:55 pm
content: Part datasheet can be found in this thread...https://www.eevblog.com/forum/beginners/identify-component-224708/

author: gkmaia
author_rank: Frequent Contributor
timestamp: January 04, 2020, 09:01:47 pm
content: Quote from: Gyro on January 04, 2020, 08:53:55 pmThanks!!!!
Troublesome Ribbon Cable - Page 1
Forum section: electronics / repair

author: NivagSwerdna
author_rank: Super Contributor
timestamp: March 30, 2020, 01:20:00 pm
content: A timer that keeps track of a door outside has stopped working... specifically the keys are no longer recognised... I am pretty sure this is due to corrosion on the ribbon cable which joins the front panel to the PCB.But it's a weird cable... it doesn't seem to have metal inside... is this printed somehow? How can I join to it?

author: senso
author_rank: Frequent Contributor
timestamp: March 30, 2020, 03:11:31 pm
content: Conductive paint, you will have to lift one layer of plastic that is covering the paint, and using maybe some car glass heater(rear defroster) repair paint, paint over the traces to connect them again.

author: Ian.M
author_rank: Super Contributor
timestamp: March 30, 2020, 03:21:55 pm
content: If there's enough slack in the cable, you may be able to simply trim a bit off the end so the socket contacts meet undamaged parts of the traces. However, you *MUST* *NOT* pull the cable tight enough that it bends tightly round any sharp edges, or attempt to reform any sharp creases, as it almost certainly has lost a significant amount of plasticiser since it was manufactured so will now be likely to crack if its left seriously stressed.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: March 30, 2020, 03:32:21 pm
content: Quote from: Ian.M on March 30, 2020, 03:21:55 pmThat was my Plan A... but I didn't have any luck. I ordered some 'silver glue' from China and will try again in a few weeks.

author: senso
author_rank: Frequent Contributor
timestamp: March 30, 2020, 03:38:32 pm
content: Also springs 1 and 8 dont seem to be making good contact with the ribbon.
True Fitness XLC900 Exercise Bike Display Console Assembly - Page 1
Forum section: electronics / repair

author: rcarlton
author_rank: Contributor
timestamp: November 03, 2019, 10:59:12 pm
content: I have a True Fitness XLC900 Elliptical Display Console Assembly that had the screen smashed. The console is fairly new, about 2011 to 2012. The screen needs replacing, the only number I can find on it is 15073t2. I feel pretty confident that this is all that is wrong with the unit. Need help finding a replacement screen.
Try to repair a pretty large black solid circle on LCD screen  - Page 1
Forum section: electronics / repair

author: abdulbadii
author_rank: Frequent Contributor
timestamp: October 05, 2021, 12:52:48 pm
content: How do we repair a pretty large black solid circle on LCD screen of laptop or else ?The black circle diameter is ~ 17 mm. What amazing is the circle is really a perfect circle not other shape people have often reported on such issue as an arbitrary shapeAny useful guide will be appreciated

author: voltsandjolts
author_rank: Unknown
timestamp: October 05, 2021, 01:02:34 pm
content: Are you sure it's not a sticky label

author: xrunner
author_rank: Super Contributor
timestamp: October 05, 2021, 01:06:50 pm
content: Quote from: abdulbadii on October 05, 2021, 12:52:48 pmPicture(s) ? ...

author: Fraser
author_rank: Super Contributor
timestamp: October 05, 2021, 01:11:05 pm
content: LCD panels are not normally repairable and the fault you describe is terminal. A stuck pixel can sometimes be brought back to life by light pressure on it to reconnect the faulty part in the TFT drive but that is about all that can be done with these panels. Start looking for a replacement panel.

author: Fraser
author_rank: Super Contributor
timestamp: October 05, 2021, 01:20:41 pm
content: As to what you are seeing…. It is a capillary action LCD bleed that expands evenly from the point of failure unless influenced by differential pressure on the panel. If you press around the perimeter of the circle it will likely start to change shape as the fluid is forced elsewhere. As I said…. Terminal. I just replace the LCD panel on any laptops suffering frin this issue and all is well again. LCD TV’s can be more of a challenge due to lower availability of donors with working LCD panels.A TV can easily become beyond economic repair these days as prices of new units have dropped significantly.

author: BrokenYugo
author_rank: Super Contributor
timestamp: October 06, 2021, 12:08:26 am
content: Unless this is a software induced problem you change the whole panel as an assembly.

author: james_s
author_rank: Super Contributor
timestamp: October 06, 2021, 12:14:24 am
content: It's extremely unlikely that the problem is something that can be repaired. You have to replace the panel itself, which may or may not be a standard part that is available.

author: xrunner
author_rank: Super Contributor
timestamp: October 11, 2021, 12:30:18 pm
content: Yes I see that now.Solution: Replace the panel or entire monitor.
Trying to figure out the value of a bad xtal. - Page 1
Forum section: electronics / repair

author: itscoldoutside
author_rank: Contributor
timestamp: June 16, 2024, 12:08:05 pm
content: I am trying to repair a JFJ Easy Pro disc repair machine, I've narrowed the issue down to a bad crystal. Sadly it's not marked and the micro controller it's connected to either has fake markings or is a custom chip maybe? It controls the timer, the leds and the relay for the motor. The micro is marked N79A1021 and you can see the crystal next to it in the picture, is there maybe a few 'standard' values I can try? I've tried probing the bad one when it does run (heat gets it going briefly) with the oscope but it just stops running as soon as I probe it.Thanks.

author: ArdWar
author_rank: Frequent Contributor
timestamp: June 16, 2024, 12:25:56 pm
content: If that's the usual ~2mm diameter then it should be 32.768kHzIt would be ridiculous otherwise. Just why...

author: Whales
author_rank: Super Contributor
timestamp: June 16, 2024, 12:28:46 pm
content: Your scope probe might be enough load to stop the crystal if the drive circuit is very weak.Yes that's probably going to be a 32.768KHz watch crystal.

author: itscoldoutside
author_rank: Contributor
timestamp: June 16, 2024, 12:35:52 pm
content: Thanks guys I'll try one and report back.

author: magic
author_rank: Super Contributor
timestamp: June 16, 2024, 01:04:36 pm
content: I think it's a 3mm diameter can and I have seen some few-megahertz crystals in this package in consumer electronics.

author: BILLPOD
author_rank: Frequent Contributor
timestamp: June 16, 2024, 01:11:51 pm
content: Once it is detached from the PCB, there may be numbers on the back, butmay require some optical magnification

author: SeanB
author_rank: Super Contributor
timestamp: June 16, 2024, 04:31:37 pm
content: Do not probe directly, just have the scope probe near, and see the biggest signal riding in the noise. Also try turning the crystal around, it just has to oscillate for a few seconds to have you run through the timebase to see what the frequency is. Though I have seen them with 1MHz, 2MHz, the most common is 32 kHz.Edit to give a datasheet of what is available in that package.https://mantech.co.za/Datasheets/Products/DTXXXX.pdf

author: itscoldoutside
author_rank: Contributor
timestamp: June 16, 2024, 05:22:58 pm
content: Thanks again guys, I took a crystal from an old watch and it's working 100% now.
Trying to find a slide switch - Page 1
Forum section: electronics / repair

author: FreddHoff
author_rank: Newbie
timestamp: July 10, 2025, 07:48:07 pm
content: I'm new to electronics repair and I'm trying to figure out how to find replacement slide switch without the original for a Kobo Aura N514 ereader.I found this video of the exact repair showing the switch and I have been looking on thissiteto try and find a replacement.What is the best way to go about finding a suitable replacement switch ? Or does anyone know the exact one needed?

author: Swake
author_rank: Frequent Contributor
timestamp: July 10, 2025, 08:42:03 pm
content: You'll have to go to the usual distributors such a Mouser, Digikey, TSMC, LCSC and search for slide switch in their catalog. Try filtering on something you know such as the dimensions. Then look at the pictures one by one...Might be this one:https://lcsc.com/product-detail/Slide-Switches_ALPSALPINE-SSAL120100_C335996.html
Trying to find this component online - Page 1
Forum section: electronics / repair

author: aaron94
author_rank: Newbie
timestamp: March 30, 2020, 03:17:34 am
content: Hi!Would anyone be able to help identify this THT ribbon cable connector?It’s a pretty ancient device. I was hoping to buy a pack of replacement connectors online but I’m not having any luck and wondering if I’m not using the correct query.Thank you!

author: Psi
author_rank: Super Contributor
timestamp: March 30, 2020, 04:11:21 am
content: Try some of these termsFFCFPCblack5 pos5pospushconn
Trying to fix Dse Q-1802 oscilloscope same as a PS 200 - Page 1
Forum section: electronics / repair

author: harry dalek
author_rank: Newbie
timestamp: February 24, 2023, 10:02:57 am
content: I am Trying to fix a Dick smith Q-1802 oscilloscope has also been rebranded to a Toptronic T200 and digitor Q-1802 pintek PS-200 oscilloscope.It Started off with a dead primary on the transformer which i think was undersized for the scope in the first place .PS 20-60mhz (1).pdf

author: Dave.
author_rank: Newbie
timestamp: December 06, 2023, 10:55:24 pm
content: Hi Harry,also have Dick Smith Q-1802/Pintek PS-200.My problem is no EHT. Also the 2SD880 had been removed. When a (similar) TIP31 was fitted it just got very hot with no oscillation. Got a new T-850 EHT transformer free from Pintek: same result.All components in this area OK except one of the two EHT diodes which broke down at 50 volts instead of 1KV plus. Replaced both with 1N4937's.Still gets hot, no oscillation.Relaced the 2SD880 with a Darlington: now it oscillates but still draws too much plus 12 volt supply beyond what the 7812 can manage.The 741 is fine.Now considering a multivibrator to feed the Darlington's base, ignoring the 741 EHT regulator circuit and T-950 feedback winding completely.Would appreciate any ideas from others. Probably should have started a new topic but don't know how to do that.
Trying to hack the DSOX1204A - Page 1
Forum section: electronics / repair

author: sprit
author_rank: Regular Contributor
timestamp: October 27, 2024, 02:37:31 am
content: Hello everyone, have a nice day.I have a DSOX1204A, after tearing it down to find the UART port, I found that the motherboard has some changes compared to the old version. The debug port has been removed from the new board. I have been struggling since yesterday and still can't find the location of the RX and TX ports, can anyone tell me?I am planning to change the resistor value to change its license like 1000x, is that possible? By the way, does anyone have pictures of the 1204G model? I want to turn the A version into a G version by adding components.It seems that Keysight's move from Windows to Linux makes it harder to hack, has anyone succeeded in doing that? Thank you very muchSincerely, Jing Feng

author: coromonadalix
author_rank: Super Contributor
timestamp: October 27, 2024, 08:22:39 am
content: maybe this video ?https://hackaday.com/2017/03/10/keysights-new-1000-x-scopes-get-double-hertz/