hybridfree/eevblog-posts huggingface dataset:
Corsair ATX CX430 repair - Page 1
Forum section: electronics / repair

author: Gcsillaz
author_rank: Contributor
timestamp: April 23, 2021, 07:58:23 pm
content: Hello everyone!Friend of mine described that while he was sleeping suddenly he heard a loud "zooooom" followed by a big "puff" and woke up. When he turned the lights on he saw a lot of smoke coming from his PC (Which he turned off before sleeping, but was still connected to the outlet and PSU switch on).He asked if I could take a look at his PSU and see what happened.Upon opening up there was a lot of electrolite liquid and the bulk cap had poped off... Also the diode and the mosfets of the PFC part are all shorted (remove from the pcb to test)That was all I could find and test upon inspection...I would like to know if you guys could help me regarding two topics.1 - The diode is a STTH806D and the FETs are STF13NM60ND. I've searched for them on the area but could not find them... From your guys experience do you think I could replace them for: FQPF10N60C (Little lower Amp + Higer RDs(on)) and for the Diode I have two options which are RURP1560 (0.4 higher Vforw and 18ns Higher reverse time) and the MUR 860.2 - What could possible be damaged fromt his failure? The secondary side could?Thanks in advance!

author: Rasz
author_rank: Super Contributor
timestamp: April 28, 2021, 10:10:23 pm
content: you can usually omit the PFC completely and the supply will run (with bad power factor), so start with replacing the bridge(did it also die?) and main cap

author: TheMG
author_rank: Frequent Contributor
timestamp: April 29, 2021, 12:47:29 am
content: The PFC controller and it's associated components could be suspect too and should be checked before replacing the power components.Whenever I see the bulk capacitor in a PFC power supply explode, it's usually a result of a significant over-voltage due to the PFC boost converter going open-loop for one reason or another. An open resistor or solder connection in the feedback loop is all it takes!

author: Rasz
author_rank: Super Contributor
timestamp: April 29, 2021, 06:53:34 pm
content: Sorry, I wasnt too clear. Of course remove all the PFC components, leaving just the rectifier and main cap before the actual power supply stage.
Corsair CV650 PSU with burnt output coil - Page 1
Forum section: electronics / repair

author: andy_cristea
author_rank: Newbie
timestamp: February 04, 2025, 04:01:52 pm
content: Hello!I have this Corsair CV650 computer power supply and it has a burnt output coil. The PSU powers on, this coil gets red hot and starts to smoke and PSU shuts down.Of course, no schematic or parts list is available.Does anyone know where I can get a replacement?Should I attempt to wind one myself? I found similar sized toruses (tori?) online but I have no idea about the characteristics of the original one.I've attached a picture of the offending article.Thanks!

author: benj38
author_rank: Frequent Contributor
timestamp: February 05, 2025, 09:39:11 pm
content: These rarely fail on their own. Most probably this is the victim of another fault, which you must find first.

author: mikerj
author_rank: Super Contributor
timestamp: February 05, 2025, 09:52:13 pm
content: Almost certainly has shorted turns. The core may be reusable if not broken, so you could try rewinding it with the correct gauge wire and numbers of turns.

author: floobydust
author_rank: Super Contributor
timestamp: February 05, 2025, 10:33:32 pm
content: Can you make out any lettering or writing on the core? There seems to be some on this teardown pic I found. Some of it would be the core diameter.I would carefully take it apart, to count the number of turns and direction on each winding. Take pictures etc.You'd have to reverse-engineer it, in order to make a new one. The old core is garbage now, they get damaged by the heat.This Corsair is a low cost PSU using Teapo capsI would not expect those to have lasted.Corsair CX750M has the same issue with burning up the inductorhttps://linustechtips.com/topic/890851-corsair-grey-label-cx750m-burning-smell-fault-finding-and-repair/I did not see anyone find a replacement core and wind it by hand, should not be too difficult. There is no colour code on them though.

author: andy_cristea
author_rank: Newbie
timestamp: February 10, 2025, 11:52:26 am
content: @benj38The PSU ran without cooling for a couple of years on a pretty beefy system (i9 10th gen with GTX1660SUPER GPU). The PC was stood on a very shaggy carpet and PSU was mounted with the fan down, in one of those cases that draw air from below. I don't think there's anything else wrong with it.@mikerjThe coil ran red-hot so I'm pretty sure the core cannot be used anymore due to curie point being exceeded.@floobydustNo markings. The paint is burnt on it. I did find some cores that look like that size, the T132-26 or T130-26. I also found the smaller gauge wire. I will disassemble it once I have the thicker wire.How can I check if the newly wound one is OK? Check it's temperature with some high load? Scope the output for HF ripple?Indeed, it has Teapo caps. Are they bad? I was under the impression that Teapo is a good brand. Should I recap it?Thanks!
Corsair RM850x PSU repair - over current protection? - Page 1
Forum section: electronics / repair

author: W1ngl3t
author_rank: Newbie
timestamp: November 14, 2023, 11:38:54 pm
content: Hi all,I have a Corsair RM850x PSU that refuses to turn on.The 5v standby rail is working fine, but when I try to turn it on it shuts itself off in a few milliseconds. There are no obvious shorts to be found so I started probing the supervisor IC and the switching controller to see if it was the over/under voltage protection or over current protection (OCP) being triggered and causing the shutdown.With my oscilloscope I can see that the 12v, 5v and 3.3 rails are coming on for a short period of time. The 12v rail reaches 12v and almost immediately starts to drop voltage, while the other two remain constant. Furthermore, I can see spikes in excess of 1v on the current sense line and according to the documentation 1v is the threshold. What I don't know is if these spikes are enough to trigger OCP and this is what I would like to ask for help with.I have attached pictures from the oscilloscope showing these spikes hoping someone can confirm or refute that this is indeed the smoking gun.The "A" line on the oscilloscope represent 1v.The OCP sensing IC is the Champion CM6901X. Datasheet can be found here:https://pdf1.alldatasheet.com/datasheet-pdf/view/311445/CHAMP/CM6901XIP.htmlAny help would be appreciated!thanks

author: magic
author_rank: Super Contributor
timestamp: November 15, 2023, 07:44:20 am
content: Quote from: W1ngl3t on November 14, 2023, 11:38:54 pmFYI, on modern PSUs lower rails are often derived from 12V by buck converters, which is consistent with your observation.Where is the noisy signal coming from?Are you sure you are probing it right? Attach the ground clip close to the signal trace, or to the ground near the IC receiving the signal.Do you see similar spikes when it's turned off?

author: W1ngl3t
author_rank: Newbie
timestamp: November 15, 2023, 10:30:15 pm
content: Hi magic,Thank you for your response.I am aware that the 12v rail feeds 3.3v and 5v, but the 12v rail -in my opinion- isn't supposed to enter a steady decline right after reaching 12v. I'll show you what I meanWhen the 3.3v and 5v rails are switched off the 12v rail momentarily jumps back up a bit, but this could be perfectly normal. Btw, the 3.3v and 5v rails are managed by a separate IC and seem to hold their intended voltages perfectly.My other hypothesis is that the 12v rail is triggering under-voltage protection, but I have no way of proving it.Regarding the probing, I've taken new measurements by moving the ground probe to the IC receiving the signal, but I don't see much improvement. Do you think all the spikes above 1v are just noise and are probably not triggering OCP?
Could DeoxIT be used to clean PCB sockets and connectors? - Page 1
Forum section: electronics / repair

author: Kinkless Tetrode
author_rank: Regular Contributor
timestamp: June 22, 2019, 10:33:15 am
content: DeoxIT is great on pots and contacts, but could it be used to clean PCBs, sockets, and connectors also? Or would it be better to stick with iso alcohol for PCBs?

author: madires
author_rank: Super Contributor
timestamp: June 22, 2019, 12:16:36 pm
content: DeoxIT is meant to clean electrical contacts. And yes, IPA is the right cleaner for PCBs.

author: Bud
author_rank: Super Contributor
timestamp: June 22, 2019, 01:48:24 pm
content: DeoxIT is an expensive product, would be unwise to use it in applications like PCB cleaning.

author: Ian.M
author_rank: Super Contributor
timestamp: June 22, 2019, 01:49:59 pm
content: +1Why would you even consider using a far more expensive cleaner, not specified for the application, that has additives that may attract dust and other contamination when spread all over a PCB?

author: Kinkless Tetrode
author_rank: Regular Contributor
timestamp: June 22, 2019, 02:15:03 pm
content: Thanks, everyone!
Could Use Some Help Identifying A Resistor From A Power Supply - Page 1
Forum section: electronics / repair

author: Guybrush3pwood
author_rank: Newbie
timestamp: March 16, 2025, 07:21:24 pm
content: Thinking about possibly restoring a Power Man FSP300-60BTV power supply from around 2000 after I found I was only getting 10v on the 12v rail. Guessing it probably needs a recap, but while poking around the insides, I noticed a resistor that had seen better days.As you can see in the attached photos, the ceramic outer coat has broken off and I only have the colored rings on the end, a violet and gold. I put the thing into a component tester and on my multimeter and I'm getting somewhere around 7.4 to almost 8 ohms resistance. Problem is I'm not sure if that's the same as it originally read or if that's just what it's reading now that its damaged. I tried googling some images of the same power supply but sadly, they're all covered with heatshrink so I can't get a good look at its markings.I'm almost certain it's a 7.5 ohm resistor given the bands that still exist and the readings I got, but I just need a sanity check to be sure. Would love to know your thoughts!

author: Jetecnet
author_rank: Contributor
timestamp: March 18, 2025, 01:01:18 pm
content: I'd say that resistor is fine, beats me why they would put shrink on it. Fiberglass tube insulation would be better. JC
Could you help me ID a component on a LiPo protection board? - Page 1
Forum section: electronics / repair

author: TT_Vert
author_rank: Regular Contributor
timestamp: June 12, 2022, 10:12:06 pm
content: Had this in beginners area but got not bites so perhaps it was the wrong forum?This is for a 1S LiPo I am using for a project in the shed.First let me apologize for my schematic, I've never really drawn one and I know looking at it will trigger a good many of you. The component is a SOT-26 and the marking was y1ig (Removed from PCB in pic and is marked U1 on the solder mask). I didn't draw in all of those 6 other chips (Also not able to find data on those based on markings) as they are all wired in parallel so I only drew in one. U1 is the component in question and I think it's a MOSFET and i feel it may be this one . Of course the # on the PCB comes back to nothing either. I "assume" that pin one is on the side o U1 w/ the line and if so pin 5 (Drain2) of this chip is not in use.Thanks much guysDave

author: fzabkar
author_rank: Super Contributor
timestamp: June 13, 2022, 02:26:09 am
content: This IC matches the pinout:DW01A, H & M semi, Protection IC for One-Cell Lithium-Ion / Lithium-Polymer Battery Pack, SOT-23-6:https://hmsemi.com/downfile/DW01A.PDFThese also have the same pinout:S-8261 Series, Ablic, lithium-ion / lithium polymer rechargeable battery protection IC, SOT-23-6:https://www.ablic.com/en/doc/datasheet/battery_protection/S8261_E.pdfAP9101C, Diodes Inc, protection IC developed for lithium-ion/lithium polymer rechargeable battery, SOT26:https://www.diodes.com/assets/Datasheets/AP9101C.pdfFS312F-G, Fortune Semiconductor, lithium-ion/polymer battery protection, marking 312F, SOT-23-6:https://www.ic-fortune.com/upload/Download/FS312F-G-DS-12_EN.pdfhttps://www.jscj-elec.com/gallery//file/CJDW01A%20Rev-1.0%20.pdf(CJDW01A)https://www.ecmos.com.tw/wp-content/uploads/2022/02/EC9523.pdf(EC9523)http://st.semi-star.com/3/30342d76071d4e2a3866b5aff3276fc3.pdf(SSC5918)If you want to keep looking ...https://ipv4.google.com/search?q=filetype%3Apdf++lithium+%22battery+protection+ic%22+%22sot23-6%22+OR+%22sot-23-6%22+OR+%22sot26%22

author: Peabody
author_rank: Super Contributor
timestamp: June 13, 2022, 05:01:23 am
content: And the other six chips - the Q chips - are very likely the FS8205A, which is a dual N-channel mosfet.

author: fzabkar
author_rank: Super Contributor
timestamp: June 13, 2022, 05:58:31 pm
content: The dual MOSFETs look like Alpha & Omega parts, maybe AO8810.AO8810, Alpha & Omega, Common-Drain Dual N-Channel MOSFET, 20V, 7A, 20mOhm RDSon, TSSOP8:http://www.aosmd.com/pdfs/datasheet/AO8810.pdf

author: TT_Vert
author_rank: Regular Contributor
timestamp: June 23, 2022, 12:32:42 am
content: Thank you all for the info.
Could you help me to fix the problem that get from 121GW multimeter - Page 1
Forum section: electronics / repair

author: Aniwat_su
author_rank: Newbie
timestamp: July 23, 2020, 11:24:26 am
content: Hi . Could you help me to fix the problem that get from 121GW multimeter. I bought it from website and then It's can't use as well. you can see on the video:https://drive.google.com/file/d/1Rxx9sBTdvFitgmP3Ob37sN5uFWsPeg3n/view?usp=sharingplease respond back if you can help me.Thank a lot.

author: coromonadalix
author_rank: Super Contributor
timestamp: July 23, 2020, 05:22:53 pm
content: you should post in the 121gw threads here, in the test equipment sectionand your link require a registration, and once entered we need to ask your approval, not the best way to get help with no problems description ?
Cover removal Tek T935 input board - Page 1
Forum section: electronics / repair

author: marnav1
author_rank: Contributor
timestamp: December 17, 2024, 12:27:54 am
content: Any suggestions for disassembly? I'd like to clean the switches underneath. Very little room to remove those nuts, its smaller than it looks in the picture.

author: alan.bain
author_rank: Regular Contributor
timestamp: December 17, 2024, 10:58:21 am
content: I seem to remember having to resort to needle nosed pliers (horror) for the BNC back nut. I would love to know what the correct tool is.... Don't forget to desolder the resistor first or it is easy to destroy.Alan

author: ondraN
author_rank: Regular Contributor
timestamp: December 17, 2024, 11:32:28 am
content: For this type of work I use nose pliers and radius nose pliers. After loosening the nut I use tweezers to finish. Disassembly is easier than reassembly, so I wish you good luck.

author: marnav1
author_rank: Contributor
timestamp: December 17, 2024, 12:14:22 pm
content: Ok ty gentleman, this sounds like if you dont really need to mess with it dont lol.

author: ondraN
author_rank: Regular Contributor
timestamp: December 17, 2024, 12:38:16 pm
content: I'm currently working on repairing and renovating a Tek 453. It's really hard work and a real puzzle. The T935 is amazingly simple in comparison
COWIN 7 Wireless headphones - Page 1
Forum section: electronics / repair

author: daveyk
author_rank: Frequent Contributor
timestamp: August 19, 2022, 11:41:47 pm
content: Kid brought me his headphone smelling like something burned up. The side that contains the battery has only one active part. Looks like the li charger IC. It is 5 pin marked 55BA and quite burned up.In the meantime, I order another pair for him off of amazon, but like any tech, it would be cool to fix the old ones. The other ear that contains the bluetooth logic isn't damaged as far as I can tell, only the side with the lithium battery and this chip. USB power goes to this chip and the battery hooks to it.Anyone with experience fixing something like this or where to find schematics for wireless headphones?

author: fzabkar
author_rank: Super Contributor
timestamp: August 19, 2022, 11:47:12 pm
content: Is there an FCC ID anywhere?TP4055, Top Power Asic, single-cell Li-Ion battery charger with reverse battery positive and negative polarity protection, 4.2V, 500mA, marking 55bM, SOT-23-5:http://www.tp-asic.com/res/tp-asic/pdres/201203/TP4055_42.pdfhttp://www.tp-asic.com/te_product_a/2009-05-20/1238.chtmlhttps://www.aliexpress.com/i/2255800831044176.htmlLinear Tech appears to have pin-compatible chips, eg ...https://www.analog.com/media/en/technical-documentation/data-sheets/405442xf.pdfI'm betting this is the original headphone manufacturer:https://fccid.io/2AB5Thttps://fccid.io/2AB5T-E7

author: daveyk
author_rank: Frequent Contributor
timestamp: August 20, 2022, 04:31:20 am
content: Wow, that's exactly the part. Thanks!! How did you find it?

author: daveyk
author_rank: Frequent Contributor
timestamp: August 20, 2022, 04:52:37 am
content: Order a couple packs of those chip and some battery varieties from Alli. I alsi found some nice assortment of Microusb sockets. I should have in about 2-3 weeks.Thank you again!

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 20, 2022, 05:05:11 am
content: If space allows, add a 1 ohm or so resistor in series with the USB input, that will help keep the chip cooler and avoid a repeat failure.

author: fzabkar
author_rank: Super Contributor
timestamp: August 20, 2022, 07:06:04 am
content: Quote from: daveyk on August 20, 2022, 04:31:20 amI performed a Google image search for "SOT-23-5" "lithium charging" and found similarly marked ICs from the same manufacturer. Then I went to the manufacturer's web site and examined the products for likely candidates.
Cracking SMD resistor on treadmill electronic board - Page 1
Forum section: electronics / repair

author: LeonardCC
author_rank: Newbie
timestamp: March 13, 2025, 09:50:42 am
content: Hi,Please bear with me, although I did some electronics in uni, I'm at a loss nowadays, I somehow forgot most of it.Here's my issue. My treadmill started making an electric cracking sound when decreasing the elevation. I took the cover off and I noticed a component on the electronic board cracking and emitting small flames. I think it's an SMD resistor.Would you please guide on how to fix this? The treadmill is very heavy, moving it down on 4 flights of stairs and back up for a resistor is not an option for me. Dismounting the electronic board is surely a better option, but there are 10 cables stuck in it, glued. I'm afraid I might damage it trying to unglue them all. So the only option would be to get a soldering gun (is that how it's called in English?), scratch the resistor off, and glue a new one, finicky as it might be without dismounting it.Is that a correct assessment, did I get it completely wrong, or do you have a more practical solution?In the attached image I highlighted two of them, the one on top is undamaged, and I managed to focus on it, the one below, in the red rectangle, is the damaged one, I can't focus on it and the writing is not that clear since it's cracked, but it's the same as the one on top, it has 1000 written on it.Bonus question: Provided I don't use the treadmill elevation feature, do you reckon it's safe to use it for time being?Thanks!

author: cruff
author_rank: Regular Contributor
timestamp: March 14, 2025, 02:27:03 am
content: I'd look for another problem that may have caused excessive current to be drawn through that resistor. Examine the wiring to make sure a cable didn't get pinched and shorted while you were lowering the treadmill. If not, there may be another cause.

author: Poroit
author_rank: Frequent Contributor
timestamp: March 14, 2025, 09:29:14 am
content: G'day LeonardCC,That is a 1000 ohm resistor and it could be associated with the component that switches the relay coil.As per@cruffmentioned...some other component is causing excess current draw.See if you can track down a circuit for yours or a similar treadmill.You should be able to use the treadmill without the ramp feature but you just won't get the same workout result.Mind you...if it bursts into flames you will run faster

author: reodor
author_rank: Contributor
timestamp: March 14, 2025, 11:41:01 am
content: The resistor is 100 ohm. The first digits (three in this case) are the first digits of the resistance value, while the last digit indicates how many zeroes to add.So, 1000 means a value of 100 with zero zeroes added. 1000 ohm would be written as 1001.This method is useful because resistors can have very high values. Imagine trying to print 1 Mohm on a resistor that small. 1000000 is a lot of digits, while 1005 is much more elegant.Through-hole resistors with colour bands use the same system, where the last band indicates number of zeroes.
Crackle and pop during playback on reel to reel Otari MX5050 - Page 1
Forum section: electronics / repair

author: digicube
author_rank: Newbie
timestamp: February 15, 2022, 09:45:11 pm
content: My machine recently started playing all tapes with crackle and pop. It has to be the machine since it occurs on all tapes I've tried. Any idea what's causing it? Here is what it sounds like. After demagnetizing and applying deoxit on the volume knob, the pops are reduced but not eliminated.https://drive.google.com/file/d/1FkPRizuQgdw1KvfTezrBn071r6ODhNOW/view?usp=sharing

author: Audiorepair
author_rank: Frequent Contributor
timestamp: February 15, 2022, 09:55:28 pm
content: Thats far too rhythmic and repetitive to be anything other than motor related.There are also bursts of 60 Hz ripple in there, so possibly a dodgy motor overloading its power supply, or a dodgy power supply can't feed the motor.Edit: Or something seized mechanically.
Craftsman 20V charger Conversion 110v to 220v - Page 1
Forum section: electronics / repair

author: Chipson
author_rank: Newbie
timestamp: May 15, 2022, 08:39:41 am
content: Hello everyone. I got a Craftsman 20V charger which is 110V but in my country the AC voltage is 220/Does anybody have an idea how to convert that charger? ( is that possible? ) if you ever made this please explain.Thanks.

author: tunk
author_rank: Super Contributor
timestamp: May 15, 2022, 11:12:36 am
content: What's the voltage ratings of the yellow cap and the one you've lifted?Also do a web search with these keywords: eevblog 110v 220v

author: Audiorepair
author_rank: Frequent Contributor
timestamp: May 15, 2022, 01:05:25 pm
content: Any old transformer with 2 x 110v primaries can be wired as an autotransformer to get 110v from 220v.

author: Chipson
author_rank: Newbie
timestamp: May 15, 2022, 02:10:26 pm
content: Quote from: tunk on May 15, 2022, 11:12:36 amYellow cap votlage is 250VBlack one Voltage is 200V
Craftsman 82357 DMM repair - Page 1
Forum section: electronics / repair

author: Roman oh
author_rank: Regular Contributor
timestamp: November 07, 2022, 10:10:48 pm
content: My old faithful Craftsman 82357 DMM is acting up on the Ohms ranges. I would like to try to fix it. I have done some searching, without luck. Does anyone know of any schematics or other info (OEM data, perhaps?) that might be available?ThanksRoman

author: coromonadalix
author_rank: Super Contributor
timestamp: November 07, 2022, 11:43:39 pm
content: open carefully the meter take some photos and try to check the main ic if its not under a black blobsome software for it ??http://greyghost.mooo.com/82357/

author: coromonadalix
author_rank: Super Contributor
timestamp: November 07, 2022, 11:53:17 pm
content: this thread seems to give an answer for the chipsethttps://www.badcaps.net/forum/showthread.php?p=888407attached datasheet some circuit in it
Crazy HP 3478A multimeter - Page 1
Forum section: electronics / repair

author: ik5mic
author_rank: Newbie
timestamp: December 03, 2015, 11:30:14 pm
content: Hello,my working HP 3478A multimeter has become crazy.At first, last week, it started with U.C. ROM FAILED message at boot, immediately recovered (functional multimeter). After a few minutes of warm-up, and cycling again off-on, the error disappeared.Now it always displays SELF TEST, U.C. ROM FAILED, and several other messages (e.g.: A.D. LINK FAIL, U.C. RAM FAILED), then after a few seconds the display shows garbage. While the display changes, the input relays switch in a random sequence.I have checked the power supply lines and ESR for capacitors, but everything is O.K..Any suggestions for further investigation? Similar experiences?Thank you and regards.Alessandro

author: MarkL
author_rank: Unknown
timestamp: December 04, 2015, 07:19:49 pm
content: Have you worked through any of section 7-D on processor troubleshooting in the service manual?http://bama.edebris.com/manuals/hp/3478a/If not, start there.What equipment do you have available for debugging this? Scope? Logic analyzer?

author: yo0
author_rank: Regular Contributor
timestamp: July 09, 2019, 09:08:54 pm
content: mine show u.c. rom fail with every power up but go straight to measurement mode after that, measurements seems ok and on par with other dmms, other than that a this time no other reported fail at boot.no idea where to look. cold solders, battery perhaps, relays?any ideas or opinions will be really appreciated.best regards.Pio

author: coromonadalix
author_rank: Super Contributor
timestamp: July 10, 2019, 06:25:45 am
content: The start line is : check all voltages and ripple on them if yo have the right equipment, maybe your need some recapping if its not done ... check every supply lines going to the ic'sCheck the battery voltage, once the battery die you loose calibrationThere is a soft made to backup your calibration before loosing everythinghttps://www.eevblog.com/forum/testgear/free-hp3478a-multimeter-control-program/You can build a vey cheap arduino gpib adapter to work with your meterhttps://www.eevblog.com/forum/projects/ar488-arduino-based-gpib-adapter/The other problems maybe contacts / solder related, check for any crack on solder, you may have bad contacts on the front flat cable, be careful this connector is kinda special, the pins are specially formed to snap.Maybe you have corruption on an "aged" rom chip, they have life expectancy ... but the problem is, they are soldered on the main board, you have to use propers tools to remove the chip and put them on quality sockets.Maybe you can or could work with freeze spray to see if you can replicate the problem or stop it ??

author: yo0
author_rank: Regular Contributor
timestamp: July 10, 2019, 04:03:54 pm
content: thank you very much!, i will check by your recommendations, hope the rom is ok (crossfingers).best regardsPio
Creative MF8235 Power supply issue - Page 1
Forum section: electronics / repair

author: kicken
author_rank: Contributor
timestamp: August 16, 2024, 02:05:16 am
content: Greetings, my GF has a Creative MF8235 sound bar that recently stopped functioning. We discovered the fuse blew in the power connector and tried replacing it, but the new fuse blew immediately after plugging it in. I was able to pull the power supply module out of the device and did a bit of trial and error debugging by removing some components and then re-adding them one by one to see when the device would blow the fuse. It looks like the cause is an inductor, but I'm not sure if I'm correctly identifying the device. Attached is an image of the board, with the suspected bad component highlighted.With this component removed, the board no longer blows the fuse when plugged in and the output connector shows 24v as expected. Is this an inductor? I tried measuring the resistance of it and it shows zero ohms, but I'm not sure if that is a proper test for this. If I want to try and replace it, how can I determine what replacement component I need to get? Does it need to be replaced, or can I leave it out? I haven't tried installing the power supply into the sound bar again yet, but since it's showing 24v on the outputs it seems to be functional without it.Thanks
CREE Q5 Repair Advice - Page 1
Forum section: electronics / repair

author: UltimateX
author_rank: Contributor
timestamp: September 10, 2019, 02:40:17 pm
content: Hi,Just recently my CREE Q5 torch stopped working and I traced the fault to a dry joint on one side of the LED driver board diode. However, as I was removing the driver board an SMD capacitor (I think), suffering from the same dry joint issue, popped off the PCB never to be seen again.I have re-soldered the diode to the driver board and replaced the original brittle solder on several points on the driver board and the Q5 LED now lights but I am missing this capacitor, which I would like to replace (see attached photos). I tested the remaining other cap with my component tester and it detects its value as 10uF, but I am not sure if this has any relation to the missing one. Would anyone have the same single-mode Q5 CREE torch they have worked on and know the value of this cap (or resistor?) or, in any event, be able to advise me on what capacitor I need to use to replace this cap please?Many thanks in advance.

author: shakalnokturn
author_rank: Super Contributor
timestamp: September 10, 2019, 10:20:08 pm
content: According to strong exuberant joyful lucky Shanghai Yuxin Electronic Technology Co., Ltd, that would be something like a 10uF MLCC.If components are dropping off the IMS either it was very badly manufactured to start with or it's running way too hot (crap design either way...), a little thermal compound around the edge and a decent tightening of the fastening ring may help in the second case.

author: UltimateX
author_rank: Contributor
timestamp: September 10, 2019, 11:34:45 pm
content: Ah! Thank you so much for finding the schematicshakalnokturn- that's exactly what I couldn't find.I suspected as much regarding the cap value and soldered in a 10uF cap earlier, which seemed to have no adverse effects. Fortunately, I don't have to back out that change now you've confirmed it's correct with the schematic. Very much appreciated - thanks again.And just to add, I think the lead-free solder the manufacturer used was poor or perhaps here was too little flux. In any event, I decided to re-seat and solder all the components to avoid having to reopen the torch again (hopefully). Everything seems be tight and working well now. I know I dropped it a couple of times but still it's supposed to be a pretty rugged torch judging by its housing.
Crispy Tangent Evo E8 subwoofer - bin or rebuild? - Page 1
Forum section: electronics / repair

author: Lomax
author_rank: Frequent Contributor
timestamp: November 23, 2024, 08:54:43 pm
content: Friend of mine asked me if I could take a look at his Tangent Evo E8 8" subwoofer which had gone silent. Found that both main filter caps (6800uF 50V "Chang" brand) had spewed their guts and the PCB had been burned to a crisp, with the heat seemingly coming from two zeners (ZD4 and ZD3 vertically below it in photo). Even if I was able to figure out the values of burnt resistors and diodes, the FR4 itself has been carbonised to the point where it falls to pieces when you poke at it.So not really possible torepair, as such - but I could install a new amplifier in the enclosure. He's got no need for the low-pass filter since he's feeding it from an AV amplifier with a dedicated subwoofer line output. There's a beefy 27-0-27V transformer and a nice switched mains input socket that could be reused, by adding a new rectifier board with a couple of filter caps. I'm just not sure if it's worth the cost & effort!What say the forum? Bin it - or McGyver it?

author: themadhippy
author_rank: Super Contributor
timestamp: November 23, 2024, 09:17:02 pm
content: QuoteAny decent heatsinks? recently threw one of these togetherhttps://quasarelectronics.co.uk/Item/velleman-k8060-discrete-power-amplifier-200w-kitso far its done wot it said on the tin,only mod i made was upgrading the 2 psu caps from the 50v supplied to 63V as with a 30-0-30 transformer it was bit close for comfort

author: Lomax
author_rank: Frequent Contributor
timestamp: November 23, 2024, 09:33:57 pm
content: Quote from: themadhippy on November 23, 2024, 09:17:02 pmYeah! I forgot to mention that there's a very substantial black anodised heatsink on the back of the enclosure, which I would certainly want to keep forsomething. That Velleman kit is very attractively priced, and probably at least as good as the Wun Hung Lo boards I've so far been able to find on eBay... Looks like it would fit nicely on the existing heatsink as well.

author: Lomax
author_rank: Frequent Contributor
timestamp: November 23, 2024, 10:00:28 pm
content: Quote from: themadhippy on November 23, 2024, 09:17:02 pmI note the absence of a relay; does it make a loud pop when switching on/off? Did you add a volume control pot? The assembly instructions fail to mention this.

author: Audiorepair
author_rank: Frequent Contributor
timestamp: November 23, 2024, 10:10:04 pm
content: Yes, it looks like failure of the Power Amp means DC to the speaker and nothing to prevent it melting.I guess it is down to the designer of the end product to incorporate some kind of DC protection circuitry.

author: themadhippy
author_rank: Super Contributor
timestamp: November 23, 2024, 11:28:54 pm
content: Quotethers a small pop but nothing that concerns meQuoteIts just a power amp,no volume pot included,but its simple to add one if needed.
Crotech 3132 oscilloscope vertical line problem ???? - Page 1
Forum section: electronics / repair

author: Ozoz_xba
author_rank: Newbie
timestamp: March 17, 2021, 04:53:28 pm
content: Hi to all,I have an old osciloscope ,i repaired it but now i have in both channel the same problem ,or maybe it works like that i do not know ,on my test signal which is 0.2V 1khz ,on both channels it should show 1 square at 0.2v/div ,and 2 square at 0.1volt/div ,but it shows just 1 minor division at 0.2v/div ,and 2 minor division on 0.1V/div,and 4 minor division on 50us/div, is this osciloscope works like this or there should be a problem on vertical line?i have checked the vertical board but all resistors and others componemt works well . I add 2 pic of my problemhttps://ibb.co/JjZsJ3Yhttps://ibb.co/GMMmhVVThanks for any reply

author: BrokenYugo
author_rank: Super Contributor
timestamp: March 17, 2021, 09:25:19 pm
content: It's perfectly normal for an analog scope to not display the vertical component of a fast rise square wave, if that's what you're asking. Just the nature of how the crt works, the beam isn't there long enough to light the phosphor up enough to see it.
CRT bent image - Page 1
Forum section: electronics / repair

author: gkmaia
author_rank: Frequent Contributor
timestamp: November 06, 2020, 10:04:29 am
content: Would anyone be able to tell if that is a physical fault on the CRT plates? Or something else.

author: akimpowerscr
author_rank: Regular Contributor
timestamp: November 06, 2020, 10:16:01 am
content: Hard to tell with only one image of the beam at a single vertical position.It could be due to a magnetic field .
CRT - Confirm Dead (not an obvious fault) - Page 1
Forum section: electronics / repair

author: mumoto
author_rank: Newbie
timestamp: February 14, 2023, 07:11:03 pm
content: Hello,I've just restored an old (80s) computer/monitor, was working just fine until suddenly horrendous noise and lost the screen. I initially thought it was a belt slipping on the drive or similar causing the machine to crash but no, it is was actually sparks inside the CRT tube.It fires up luminous electric blue (don't want to look too closely incase I'm giving my eyes a nice dose of UVC), the phosphor doesn't glow, just noise and sparking inside the neck of the tube/electron gun. This is a single-gun monochrome monitor.With little CRT knowledge beyond basic principals is it safe to assume this is dead, or could it be a simple fix? With obvious caveats about the dangers of CRTs etc.It's an old Amstrad PCW so there are millions of them, no great shame just annoyed having retrobrited it and carried out various other repairs!Thanks,BHS

author: inse
author_rank: Super Contributor
timestamp: February 14, 2023, 09:10:40 pm
content: I only encountered noisy arcing when the FBT or multiplier was cracked.Arcing inside the tube only when the vacuum had gone…That’s as much as I rememberYou could pull off the CRT board and see what happens

author: Runco990
author_rank: Frequent Contributor
timestamp: February 15, 2023, 04:50:16 am
content: It SOUNDS like the CRT cracked and is open to air.However, it could also be the ground strap from chassis to the outside of the CRT. CHeck that first.The outside of the tube must be grounded, as the outside and inside coating form a high voltage capacitor.Sparks can ensue.

author: TomKatt
author_rank: Frequent Contributor
timestamp: February 15, 2023, 01:05:46 pm
content: It is possible for the gun assembly in the neck to short, usually due to mechanical shock or over voltages, but sometimes something just "gives out".In any event, arcing inside the neck is not a good sign and typically means the crt is shot.

author: Chris56000
author_rank: Frequent Contributor
timestamp: February 16, 2023, 07:20:31 pm
content: Hi !An easy and safe way to check is to disconnect the CRT heater leads (usually coloured brown and black) from the CRT base socket from tags 3 and 4, and connect a 12 V supply to the vacant terminals 3 and 4 from a d.c. power supply with the rest of the monitor switched off – you should be able to see the dull orange glow of the heater/cathode assembly when you power the heater separately in this way – if the CRT has air in it you will not be able to see any glow!In any case, it is obvious from the symptoms described that your CRT has lost its.vacuum causing the internal arcing, and it's a goner!Either another CRT or another monitor is the only way forward from here I'm afraid!Chris Williams
CRT Only Displays Have of Screen - Page 1
Forum section: electronics / repair

author: BlueApple
author_rank: Regular Contributor
timestamp: May 26, 2023, 12:29:32 pm
content: I got an Old VGA CRT monitor to work on. When you power it up half the screen works and the other half is completely black. Where should I start troubleshooting? Bad caps possibly?

author: wasedadoc
author_rank: Super Contributor
timestamp: May 26, 2023, 12:59:54 pm
content: Photo please.

author: BlueApple
author_rank: Regular Contributor
timestamp: May 26, 2023, 01:15:35 pm
content: Well I guess it's more of just centered, cut off at the top and bottom. Here is a photo of the Windows 98 login on the monitor (with vertical size maxed out). It is also very blurry with weird colors.

author: Haenk
author_rank: Super Contributor
timestamp: May 26, 2023, 03:15:22 pm
content: This could be just a syncing issue, try a slower H / V pace?

author: inse
author_rank: Super Contributor
timestamp: May 26, 2023, 04:18:28 pm
content: I‘d give the video settings a probability rating of 50%.Also you can see the picture is horizontally contracted at the top.I would go looking for bad caps - a hairdryer might be helpful for identification.Does the monitor have analog or OSD control of the settings?

author: BlueApple
author_rank: Regular Contributor
timestamp: May 26, 2023, 05:06:10 pm
content: I tried an old MS-DOS computer and it still doesn't work properly, it has analog controls

author: agent_power
author_rank: Regular Contributor
timestamp: May 26, 2023, 06:27:44 pm
content: Looks like a vertical deflection issue with the irregular top and foldover at the bottom, try cleaning connectors and the pots related to the vertical settings to eliminate the trivial things...Are you comfortable working inside a CRT?It's most likely capacitors, but could also be other components (resistors, ICs, etc.).What model is it? Best you can do is find a service manual with waveforms and check if the PSU and vertical section if everything is within spec

author: BlueApple
author_rank: Regular Contributor
timestamp: May 26, 2023, 07:02:07 pm
content: It's a Gateway 2000 cs1572. Yeah I'm comfortable working inside a CRT so I'll open it up and look for any obvious problems and check voltages and such.
CRT oscilloscope issue - Page 1
Forum section: electronics / repair

author: frankX0
author_rank: Newbie
timestamp: April 29, 2021, 08:19:09 pm
content: I have a Leader LBO-310A oscilloscope which was working fine until recently.It now produces "extra" lines which go from the actual beam position on the screen to a point in the middle of the CRT. Both X- and Y-channels work properly,The photos show the scope in XY-mode, where I can freely move the position of the actual measurement, but with the addition of the extra lines.I have the service manual with the schematics, which does not look over complicated. But I also cannot deduct which part is causing this failure.Help is appreciated!

author: David Hess
author_rank: Super Contributor
timestamp: April 29, 2021, 11:13:10 pm
content: That looks a lot like ripple on the supply voltages because the aluminum electrolytic capacitors have worn out.

author: bob91343
author_rank: Super Contributor
timestamp: April 29, 2021, 11:13:35 pm
content: Bad CRT maybe.

author: frankX0
author_rank: Newbie
timestamp: May 01, 2021, 05:40:00 pm
content: I would not call this DC (see attachment). Nor would I call this ripple btw.The 47uF/315V elco's are gone.Thanks for pointing me in the right direction!
CRT scratches - Page 1
Forum section: electronics / repair

author: classicsamus87
author_rank: Regular Contributor
timestamp: December 28, 2020, 10:01:44 am
content: Is there a product that if I apply it to the crt screen using fabric will remove scratches?

author: Ian.M
author_rank: Super Contributor
timestamp: December 28, 2020, 10:48:14 am
content: No. Some 'wipe on' products may partially disguise scratches, but they don't work well on CRT faceplates as leaded glass has a significantly higher refractive index than common glass and acrylics, which they are primarily intended for.If the CRT face doesn't have any sort of anti-glare coating, you *may* be able to restore localized shallow scratches with a car windscreen chip repair kit, followed by careful polishing to get the repair resin flush with the surrounding glass. If its got an anti-glare coating, or is generally scratched, its generally not worth doing as the only option is to cut back the whole face with a very fine polishing compound (sacrificing the anti-glare coating if present), and its extremely difficult to do so evenly enough to avoid optical distortion. Also there is a significant risk of failure by cracking and possible implosion due to the stresses of polishing if you go about it too vigorously or if any of the scratches have a fine crack at their bottom, so don heavy leathers, leather gauntlets and a face shield before attacking a CRT with a powered polisher!

author: CaptDon
author_rank: Super Contributor
timestamp: December 28, 2020, 08:11:25 pm
content: How big is the CRT and from what age?? Does it have a softplastic coating on the face or is it hard glass? Some CRT's havea separate face plate with resin behind it to hold it to the actualCRT bulb. Is this on a home television, or a piece of test gear.Many different approaches depending on what you have and thesafety factor that the scratch may be compromising! Got pictures??

author: Gyro
author_rank: Super Contributor
timestamp: December 28, 2020, 08:37:50 pm
content: Note that the OP has also posted the question in...https://www.eevblog.com/forum/chat/question-scratches-crt-tv/msg3389324/#msg3389324... just to avoid any frustration of duplicated information.
CRT "shaky" picture - Page 1
Forum section: electronics / repair

author: damanloox
author_rank: Contributor
timestamp: July 10, 2023, 06:54:02 am
content: Hi,I have a CRT (Sony Trinitron). I'm pretty happy with it - has really nice colours, and sharp, stable picture but... only when "warmed up". When I power it on the picture is shaky in horizontal direction (sorry - not sure how to explain it. What I mean is that it looks like all horizontal lines are slightly moving creating that shaky picture). It only happens when it's "cold" ie. for a few minutes after power on. The picture then stabilises and everything is OK. Does that on all inputs btw. My first guess was to try and change the caps but I thought I'll ask first (for a change)Any idea what may be causing it or where to start looking?

author: Roehrenonkel
author_rank: Frequent Contributor
timestamp: July 10, 2023, 09:19:01 am
content: Hi damanloox,maybe it's the degauss-coil staying on too long.Look if the PTC-resistor in line with it is okay.Good luck

author: decoder_82
author_rank: Regular Contributor
timestamp: July 10, 2023, 01:08:37 pm
content: Can you post a video that shows the issue ? It would help to further assist. Thanks

author: Vovk_Z
author_rank: Super Contributor
timestamp: July 12, 2023, 08:23:34 am
content: Dryed 50/60 Hz rectifiers large caps could be a reason too. (It's hard to tell without a photo).

author: liaifat85
author_rank: Regular Contributor
timestamp: July 15, 2023, 08:38:08 am
content: Please check if there are cold solder joints. If you find any, resolder them.

author: tggzzz
author_rank: Super Contributor
timestamp: July 15, 2023, 09:50:12 am
content: With old equipment you shouldalwaysstart with measuring the PSU voltagesand ripple. Only if those are OK is it worth moving on to other possible causes.Exactlyhowthe picture shakes could give useful information, e.g. vertically, horizontally, brightness, frequency/period, amplitude.

author: m k
author_rank: Super Contributor
timestamp: July 15, 2023, 06:26:25 pm
content: Degaussing is a bit violent, it also includes other effects.My guess is a bad supply voltage for horizontal deflection circuitry.
CRT, short scale-up distortion after warming up. - Page 1
Forum section: electronics / repair

author: Videodrome
author_rank: Newbie
timestamp: December 07, 2023, 11:47:04 am
content: Eizo T961. (21" CRT)After warming up for about 20 minutes, this scale-up glitch starts to happen in ever increasing intervals (20mins --> 15mins. etc.)https://imgur.com/a/aq6eN7kOn the inside nothing seems to spark when this distortion happens.There is slight a electrical noise, but it feels like a normal 'set resolution' sound.I just cleaned the anode area+cap and put new dielectric paste + blew pressured air into all pcb's.Sadly that didn't help.Probably going to check the solder joints next.Anyone knows what pcb board to start on? Since it happens when things get warmer, any advice on what components to check?Any help is appreciated.

author: bookaboo
author_rank: Frequent Contributor
timestamp: December 07, 2023, 12:21:33 pm
content: Dry joints are possible.The other suspect are any electrolytic capacitors, worth replacing all these anyway.
CRT Television no channels or snow  - Page 1
Forum section: electronics / repair

author: Dhanushka
author_rank: Regular Contributor
timestamp: October 25, 2019, 06:43:38 am
content: Dear all,My LG flatron 21" CRT television is only showing menu(OSD) on the screen as showing in an attached picture. All ABL side components are ok. Tuner 5 V and 33 V are ok. Two transistors around jungle IC are ok. CVBS pin of the jungle IC has signal like a noise. Is it normal? Few days ago, I have replaced the flyback and HOUT after 7 years. This was sitting about 7 years in a room. Can I solve this?Thanks.

author: shakalnokturn
author_rank: Super Contributor
timestamp: October 25, 2019, 10:11:25 am
content: Are there still analogue TV broadcasts where you are? If there is only DTV left on air it would be normal to see snow, even in a warm place...

author: Dhanushka
author_rank: Regular Contributor
timestamp: October 25, 2019, 03:08:34 pm
content: I am from Sri Lanka. Here, we still use analog broadcasting.
CRT Tube number question - Page 1
Forum section: electronics / repair

author: glaird
author_rank: Newbie
timestamp: October 01, 2025, 02:30:43 pm
content: I have previously posted a question looking for a CRT database.Maybe someone would have an answer to a specific tube number question.I would like to find a B&W CRT tube, number 17ST5490C. Someone on eBay has a 17ST5490C3. Any ideas what the 3 suffix indicates?Thanks.