hybridfree/eevblog-posts huggingface dataset:
Cleaning breadboards with a Ultrasonic Cleaner? - Page 1
Forum section: electronics / repair

author: Trader
author_rank: Frequent Contributor
timestamp: June 02, 2021, 02:18:23 am
content: I have some breadboards stored for a long time that accumulate a lot of dust (inside the contacts too), and maybe some has a little grease/oil.Can I use a Ultrasonic Cleaner to clean them?There are different (Non-Ammoniated) Ultrasonic Cleaner Solutions ... some recommendation?Thanks

author: Alex_Baker
author_rank: Frequent Contributor
timestamp: June 02, 2021, 04:02:28 pm
content: I have never done it before but I suppose as long as the solution does not corrode the metal or dissolve the plastic, I don't see a problem with using an ultrasonic cleaner.I might first try a solution of water and dish soap before any real solvent, just make sure to get it dry afterwards. Although I don't really know if breadboards rust of not.

author: Ian.M
author_rank: Super Contributor
timestamp: June 02, 2021, 04:18:34 pm
content: Cheap breadboards with steel contacts will rust - check with a magnet! If you hot rinse, shake out as much water as possible then flush with IPA and dry quickly they should be OK. However I doubt its cost effective to do so as most such breadboards deserve no more attention than widlarising them on a 100 lb anvil!A bigger problem is that although a few brands of breadboard use a hard plastic molded backing plate, mechanically fastened, many breadboards use a self-adhesive vinyl or foam rubber backing sheet to retain the contacts. If your breadboard has a stick-on backing sheet, I doubt it will survive cleaning well as its likely the glue on the backing sheet will let go in places trapping conducive contaminants between the contact strips. You'd need to peel the backing sheet, use goo-gone or similar to remove adhesive residue, then put the breadboard in the cleaner, and fit a new backing sheet made from self-adhesive plastic after the breadboard is clean and fully dry.

author: penfold
author_rank: Frequent Contributor
timestamp: June 02, 2021, 05:40:05 pm
content: It seems like a reasonable idea, hard to say if it's worth it for a particular one, but if it's so far been giving you good reliable service, then it's worth a go to see if it extends its life a little. My only concern would be for the dust after being immersed, it may clump together a bit, so maybe start by running a vacuum cleaner nozzle over it first then possibly a blast of compressed air to get the dust out before immersing.

author: David Hess
author_rank: Super Contributor
timestamp: June 03, 2021, 07:43:01 pm
content: Distilled water with a bit of dish soap would be my first choice. Then blow dry with compressed air and bake out in an oven.
Cleaning Jog or Rotary Encoder & CD lens - Page 1
Forum section: electronics / repair

author: sairfan1
author_rank: Frequent Contributor
timestamp: December 15, 2019, 04:11:17 am
content: I was servicing my CD Changer it has a jog, that by nature looks like a rotary encoder , its skipping some steps while working i believe it needs some cleaning, I want to know what kind of spray should i look for cleaning this kind of things.(available in North America)Please also advise what could be the best method to clean CD lens

author: sairfan1
author_rank: Frequent Contributor
timestamp: December 15, 2019, 03:31:47 pm
content: Is there anyone to answer this simple question, thanks

author: perdrix
author_rank: Frequent Contributor
timestamp: December 15, 2019, 04:40:59 pm
content: You don't want any contact cleaner type stuff near an optical rotary encoder. Maybe a dust blow out using "canned air"?D.

author: sairfan1
author_rank: Frequent Contributor
timestamp: December 15, 2019, 04:54:37 pm
content: You mean its an optical encoder? Sorry didn't recognize the type.
Cleaning optics inside old bulb-based projector - Page 1
Forum section: electronics / repair

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: January 19, 2024, 03:46:11 pm
content: Replacing the bulb in a Sharp PG-F325W projector, I wanna rescue this from landfill. Give it another 2000 hours of use if my little bulb replacement works.How can I clean the slab of important-looking glass that (I guess) filters the bulb output?The manual only talks about replacing the entire bulb assembly, but I've decided to try just the bulb.I'm guessing generic lens cleaning wipes would do the job? Like eyeglasses stuff.

author: Stray Electron
author_rank: Super Contributor
timestamp: January 19, 2024, 03:58:45 pm
content: Blow, wash or vacuum all dust and dirt off of the optics before wiping with any kind of tissue. Otherwise the material on it will just be a grinding compound. Fold your cleaning tissue into quarters and use each quarter only ONCE. With every wipe turn the tissue over and use a clean area. Do not use the same tissue surface to make more than one wipe of you'll just be using the girt and grime picked up on the first pass and grinding into the surface of the optics on the second pass. I really can't advise you about a safe cleaning liquid, that all depends on what the optics are made of and what coatings that they have on them. The manufacturer needs to advise you on that. (Yes, I know that it's an old item and the manufacturer is probably long gone.)"I'm guessing generic lens cleaning wipes would do the job? Like eyeglasses stuff."Yes, and do NOT use ordinary paper towels for this kind of cleaning, the fiber in them has a lot of abrasive material remaining it in. Always use tissues made for optics or lens cleaning. That apples to eye glasses as well.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: January 19, 2024, 05:08:41 pm
content: Thanks I figured it can't be that complicated and cleaning that glass slab can only help the projector to project!

author: wasedadoc
author_rank: Super Contributor
timestamp: January 19, 2024, 05:14:06 pm
content: If that slab of glass is between the bulb and the LCD panel its primary purpose is to reduce the amount of heat from the bulb that reaches the panel. As such it has very much less impact on image quality than the lens(es) on the other side of the LCD. But that is no excuse not to clean it carefully.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: January 19, 2024, 07:39:36 pm
content: Oh it blocks IR? Makes sense, I didn't notice a difference looking through it. It's a DLP projector but same idea I suppose.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: February 25, 2024, 10:10:55 pm
content: The cheap bulb I got on eBay was a bit tricky to get into the sheet metal cage, there's a little notch on the reflector that needs to line up with the metal, once that's done, it's easy. Everything works, Ms Pac-Man on the wall is pretty fun!
Cleaning push piano switches  - Page 1
Forum section: electronics / repair

author: aztecboy
author_rank: Contributor
timestamp: May 28, 2020, 11:55:46 am
content: I hope I have the name correct for these switches.These are the TRIGGER push piano type switches on my old Philips scope and are very intermittent. I have flushed them out with IPA a few times now. It works for a while and then the issue returns and I lose trigger again. VERY gently wiggling the switches (more so the Ya and Yb) clears it and I get trigger back but it is not ideal.Does anyone know of any method for cleaning these piano switches? I am really hoping I don't need to replace them all!Many thanks in advance.Ted2E0THH

author: frozenfrogz
author_rank: Frequent Contributor
timestamp: May 28, 2020, 01:22:41 pm
content: Teslanol T6 is my go-to de-oxide spray.Here are some photos I took while refurbishing a switch that is not source-able anymore.p1 + p2 switch overviewp3 - p5 contacts after disassemblyp6 - p9 after applying Teslanol T6p10 - p12 after polishing with a leather wheel

author: aztecboy
author_rank: Contributor
timestamp: May 28, 2020, 01:32:36 pm
content: Thanks frozenfrogzThose really look amazing although I don't think I can easily dissamble these switches without some serious desoldering.I'll try and find the de-oxide spray you recommend, do you think it may work with just exercising the switches in place after spraying?

author: frozenfrogz
author_rank: Frequent Contributor
timestamp: May 28, 2020, 01:45:43 pm
content: I just took pictures of this because I was curious as to what the de-oxide actually does, how effective it is on its own. I was pretty impressed!Also, the spray leaves a thin lubricating residue. I usually just spray scratchy pots and switches with this.In the pictures you can see, that it got rid of a lot of crud and oxides by simply spray-washing the contacts without even touching anything.Just flood your switches with this and actuate it a couple of times.
CMT-EX1 power supply connector - Page 1
Forum section: electronics / repair

author: Frank Ocean
author_rank: Newbie
timestamp: July 05, 2023, 01:36:48 am
content: Here's a power cable from a Cmt-ex1 Sony CD player. This connector used to be connected to the inside of the power supply. However, I had to disassemble it because I needed to replace the motherboard for the CD player. I found this CD player at Goodwill, but the wire was poorly connected with a completely different cable. It was patched together using electrical tape and wire connectors.The original cable was called E81093 (UL) NISPT-2 VW-1 105C 2X18AWG, C(UL) NONINTEGRAL SPT-2 FT1. Also the yellow plastic says Amp with a + on top of the M. this CD player is from 2000if there isn't any answer to that, how could i properly Frankenstein another cable to it without looking somewhat ugly
CMU 200 frequency band gap - board 1100.2500.02 - Page 1
Forum section: electronics / repair

author: piotrekjan
author_rank: Contributor
timestamp: July 11, 2020, 05:59:34 pm
content: Hi,I discovered in my CMU band gap in freq. range ~1.2G - to ~2.2G. In general I've found post by RF_fanatic:https://www.eevblog.com/forum/repair/rohde-and-schwartz-cmu200-rxtx-module-issues/50/Indicating that board 1100.2500.02 causes failure.In general I've removed this board from equipment - there is not to much on it, the ICs are 4 x AD829J, 4 x NE5534, 2 x AD835A, 1 x AT24C164. Additionally 2 diodes and pnp transistor. The rest is passive - resistors, capacitors, chockes.Has anyone trying to repair this board ? In general its interesting, as these components do not seems to be used in some high freq. range - but maybe.Sometimes internal bonding in ICs can fail after some temp./vib. rapid changes...Of course I can check part by part but desoldering - soldering to test board - desoldering again and soldering again does not look optimal. So first check here in forum...BTW. Has someone EEPROM content for it (I mean this 24C164 located on it) - that is my 1st suspected.Regards,

author: piotrekjan
author_rank: Contributor
timestamp: October 25, 2020, 12:27:23 pm
content: I've started playing a bit more with that.Maybe the schematic, I've created to CMU200 RXTX board will help someone. I will try go path by path to recognize where 1.2G - 2.2 G is.In terms of AUC_board # 1100.2500.02 I've checked EEPROM, it is ok. I do not exclude from suspected yet. But now focus on RX path.To those, who know -Please share what SMD components are:ANs67LDP66LDP73N43Update: I attach the LED states for different freq. bands. If LED is off means this path is not used for this freq.

author: piotrekjan
author_rank: Contributor
timestamp: November 09, 2020, 10:46:19 pm
content: Not too much progress yet, but I've done measurement to recognize what switches are on when.In enclosed pdf path for RFIN=1240MHz (so already in the band gap). All RF amplifiers seems to work correctly - valid DC voltage - what means are polarized correctly.
CMU 200 RXTX board foil caps - Page 1
Forum section: electronics / repair

author: piotrekjan
author_rank: Contributor
timestamp: October 11, 2020, 01:41:35 pm
content: Hi,I've discovered on my RXTX board that 2 foil caps have cracks on them. After desoldering one shows 85nF and 2nd shows open.Does anyone has idea can I place there ceramic caps NP0 either from some reason foil cap is necessary ?Regards,
CMU-200 WITH BIG BACK PANEL HIT WONT PASS SELFTEST - Page 1
Forum section: electronics / repair

author: Armando1989
author_rank: Contributor
timestamp: January 04, 2022, 10:21:50 am
content: Hello allEquipment arrived with big hit in the right side standoffs that messed with the back panel.Fails fm calibration and all loop tests including internal in major frequency range due to great attenuationInner inspection doesnt show unplugged connectors or visual damage, but front endo board has alarm led blinking.Have you experienced this before? Any idea what might have messed?Happy new year!

author: JohnDoe
author_rank: Newbie
timestamp: February 13, 2022, 10:19:31 am
content: Good morning,quote from another forum:"Most common issue from impact damage is X215 the flat 34 way ribbon cable that connects and controls A20 front end to motherboard A200. It pops out of the motherboard socket which prevents the A20 front end from switching causing loop back tests to fail. "Maybe worth a try?Regards,JD

author: Bicurico
author_rank: Super Contributor
timestamp: February 13, 2022, 11:25:31 am
content: Please post pictures.
CMU200 - Page 1
Forum section: electronics / repair

author: Eyecue
author_rank: Contributor
timestamp: January 21, 2020, 12:45:51 pm
content: I have a CMU200 spectrum analyzer that wont pass the self test. Further self testing shows the 8 volt supply is not correct in the RXTX unit. The motherboard LEDS show the PSU is fine for 8 volt supply. Any ideas or common points of failure inside the RXTX card?

author: Ice-Tea
author_rank: Super Contributor
timestamp: January 21, 2020, 01:04:44 pm
content: Not really, but I can offer pictures

author: Alfons
author_rank: Regular Contributor
timestamp: January 22, 2020, 07:59:20 pm
content: Are there any abnormalities in operation?

author: richnormand
author_rank: Unknown
timestamp: January 26, 2020, 05:27:48 pm
content: Just saw your post Eyecue.I also had issues with voltages on my RxTx in my CMU200.Look at the fourth pix on the first post for the location on the pass transistors for the voltage regulation on the board.https://www.eevblog.com/forum/repair/rohde-and-schwartz-cmu200-rxtx-module-issues/msg1032907/#msg1032907You will notice that one of them has been removed (the bad one!) in the photo.After fixing that it did not pass self test and that was traced to a bad coupling cap between the switching stages (later posts in that thread). I made extensions for the SMA connectors to the RxTx module and removed the RF fingers to the side rails. This sped up partially removing and reinserting the board multiple times.You really need a SA if you want to troubleshoot that board for RF issues. Finally managed to get it going but it took a while.Best of luck with it.PS: although the LEDs are lit for the 8V rail on the motherboard check them at the test points. There is a thread with pinouts of several connectors prior to my RxTx thread.https://www.eevblog.com/forum/repair/rohde-schwartz-universal-radio-communication-tester-cmu200-psu-issues/msg954718/#msg954718

author: Ice-Tea
author_rank: Super Contributor
timestamp: January 26, 2020, 08:04:46 pm
content: Hi Richard,JUst wanted to thank you for pointing out that thread. I wasn't aware it existed. I have a number of bad RXTX units, with errors ranging from marginal fails to missing bands to nothing at all so that thread is a true goldmine.Thanks!

author: Eyecue
author_rank: Contributor
timestamp: January 28, 2020, 01:15:21 am
content: Richard,Thanks for the reply! Mine does not look like yours.

author: Eyecue
author_rank: Contributor
timestamp: January 28, 2020, 01:21:51 am
content: Thanks for the reply. The calibration comes into question when the self test wont pass. I had to replace the CMOS battery in the front panel which led to some other issues but I got those taken care of.
CMU200 C5a in SOT 343 or 143 - Page 1
Forum section: electronics / repair

author: piotrekjan
author_rank: Contributor
timestamp: October 14, 2020, 08:26:44 pm
content: Hi,I'm trying to figure out what components is hidden under marking C5a...RegardsIt is HSMS-2825.The next two to identify:LPD66LPD73
CMU200 problem after 836 MHz RX filter replacement - Page 1
Forum section: electronics / repair

author: APKVblog
author_rank: Newbie
timestamp: July 30, 2024, 06:58:57 am
content: HiSo, this time, after many years of resolving other people problems i have a my own problemI did RX board 836 MHz filter replacement. All looked ok.But, whent it comes to tests and measurement it shows up that i must have screwd something. As you can see oh pictures i attached something happend and all levels are ca. 6dB less then it should be.Unit passes all test except RX/TX board.Due to lack of schematic it is hard to find what could cause this problem. It is obviously not a filter problem. Before filter replacement only 1200-2200 MHz band had low level and not passed LOOP test. Now it is low for all range.TX and wideband PowerMeter seem to work properly.Any ideas where to start looking?? Anyone has similar problem?Any advice will be appreciated.

author: snickers
author_rank: Contributor
timestamp: July 30, 2024, 09:11:10 am
content: Try to reinstall software. Same or higher version.After intalling process VERM will autatically start recalculation of callibration tables and store them to EEPROM.I'm not sure it will help ... byt try.

author: APKVblog
author_rank: Newbie
timestamp: July 30, 2024, 01:56:05 pm
content: I know that. But it gave no result in this situation.
CMU200 repair - Page 1
Forum section: electronics / repair

author: Avinoam
author_rank: Newbie
timestamp: April 11, 2020, 04:36:36 pm
content: My CMU200 bottons on panel stops to work after I push "RF CONNECTION CONTROL" botton . I have to OFF , and ON again the unit .No erors in self check . The analyzer and generator are working O.K.Can you give advice what to try ?With versionmanager I tried to load program version V5.12 , and 5.10 , it is the same .I load version V3.5 and now its working good .How can I use the internal speaker ? nothing in the manual .
CMU200 RX/TX board repair help please. - Page 1
Forum section: electronics / repair

author: eurgenca
author_rank: Regular Contributor
timestamp: November 01, 2023, 08:48:07 am
content: Hello.I goth cmu200 from evilbay and of course was a staged unit. First cmu won't power on only sb mode. I check all rails and it was o.k. So I open front module and tada... Massive leaking from battery. After changing a battery and couple surrounding elements repairing couple a trace unit was alive. At first startup strikes two disasters. Rotary encoder keeps sending signals for forward and HDD not discovered. So I try to buy new encoder, but no go. I open it and realise that always got 0.6V on the output. So I rise pull up resistor and that fixes an issue. Then I replace the HDD and reinstall new SW. Of course got the system error message: These clocks are not present: FIXED_CLOCK. This error was pretty easy reinstalling MMCX cable W33 was cure. Finally, unit boot up with no error. So it is time for cmu self test and of course RX/TX board report errors about local oscillator 1 and 3. Does someone meet this kind of error or can point me where these voltages are measured. I don't know what this error means, because I can't test cmu yet because you will not believe, front end is busted too.But let's go step by step. It is not a lot of modules to repair leftIn service manual is only a block diagram for rx/tx board what is better than nothing, but I can't 100% locate oscillator 1 and 3 on board and at that point I ask for help, you bloggers.Thanks.

author: eurgenca
author_rank: Regular Contributor
timestamp: November 01, 2023, 09:06:03 am
content: And diagram.
CMU200 switch B53v14 module from a defective unit to a working unit - Page 1
Forum section: electronics / repair

author: pe2ben
author_rank: Contributor
timestamp: June 20, 2021, 11:26:44 am
content: Hello,Do someone know what i have to do for switching a B53v14 Bluetooth unit from a defective CMU200 to a working unit?What software should i copy to the working CMU200?And how about a possible license code activating on the working one?Thanks Ben

author: chick0n
author_rank: Regular Contributor
timestamp: July 23, 2021, 10:57:31 pm
content: Heres a Video in some East European language. But you will get the hint...Then install the BLTHV5.20 Firmware package, and activate Option CMU-K53.That should do it.

author: pe2ben
author_rank: Contributor
timestamp: October 03, 2021, 10:54:39 pm
content: Okay Thank you very much !I will try it.
CN101 (PS3000pn) markers  - Page 1
Forum section: electronics / repair

author: TES13
author_rank: Newbie
timestamp: December 21, 2023, 12:59:13 pm
content: Good day! I got CN101 (PS3000pn) markers from a second-hand store. but my eeprom is damaged (see attachment). I changed the memory chip after saving the firmware, but nothing has changed, it looks like the firmware is damaged. I contacted the manufacturer, but did not receive a positive response. Now please, can someone here help me find the firmware.I also added a photo of the central control module

author: TES13
author_rank: Newbie
timestamp: January 10, 2024, 04:28:26 pm
content: Has no one ever encountered such a device?Can someone recommend another forum where you can contact?

author: TES13
author_rank: Newbie
timestamp: April 24, 2025, 03:46:47 pm
content: Help!
CNBOU 1KW inverter blown resistor - Page 1
Forum section: electronics / repair

author: tsumasuko
author_rank: Newbie
timestamp: July 26, 2024, 10:43:24 am
content: hi all,i have a CNBOU 1KW inverter for repairing. there is a blown resistor that cannot read the value. i need help who someone have same product and eligible to tell me what is the value of this resistor.thanks for any help.

author: beatman
author_rank: Regular Contributor
timestamp: July 28, 2024, 11:05:32 am
content: It looks like the aishi capacitors are bulged?Try to search for service manual with the model name or the board printed code or a member have the same machine and can help.Other option is to cut carefully with knife the resistor in the middle and measure the two halfs and from both numbers you have about the whole resistor number.

author: Phil1977
author_rank: Frequent Contributor
timestamp: July 28, 2024, 11:27:13 am
content: Out of all the components in the inverter it´s very improbable that the resistor has caused it´s own death. Even if you find the right value you will have to do more failure analysis.

author: tsumasuko
author_rank: Newbie
timestamp: July 28, 2024, 07:04:11 pm
content: yeah there are some parts broken. you saw these 2 caps and 2 more on the other side are bulged. replaced already.also find 2 mosfets(40N60) failed out of 4.this burnt resistor stay in between 12V input and PWM (SG2525) control board. looks like fuse resistor. i tried 4.7 ohm/3W but nothing happened. no short circuit by the way. ordered pwm chip and i will try again.

author: tsumasuko
author_rank: Newbie
timestamp: August 08, 2024, 10:46:38 am
content: Hi all,i am here for quick update.Instead using a guessed resistor i just added 160mA resettable fuse and changed the other broken parts that i mentioned. now its working fine. thanks for helping..
CNC Control "Grundig Dialog 11" Schematics or Info - Page 1
Forum section: electronics / repair

author: FelixLer
author_rank: Newbie
timestamp: May 09, 2020, 08:30:33 pm
content: Hello Friends,currently i have a problem with my CNC Mill and i am trying to fix it. I am at the point that i need a Schematic of the CNC Control. Does anyone have a Schematic of the Grundig Dialog 11 CNC Control?Any info or documentation about it would be helpful.Or does anybody know whre i can get Info like this?Furthermore, how do i spot an defective EPROM?Thanks in advanceFelix

author: ace1903
author_rank: Regular Contributor
timestamp: May 11, 2020, 01:06:12 pm
content: I don't have any documentation but based on pictures from the net , machines of these ages usually have problems with capacitors.Check power supply, a dried capacitor can introduce lot of noise in a digital circuit. Some capacitors can make power-on reset circuit or watchdog circuit to generatesignals with improper timings.What is the problem you are facing? Does it show coordinates? Maybe completely dead?Defective EPROM can cause self check at power up to fail. Does it show some error code?

author: Haenk
author_rank: Super Contributor
timestamp: May 11, 2020, 01:44:10 pm
content: Judging by the pictures, most SPS PCBs seem to come with a battery pack, I assume the system will not work if the voltage is too low.That's just an idea, without further error description or schematics.
adding coating on old litz inductor? - Page 1
Forum section: electronics / repair

author: coppercone2
author_rank: Super Contributor
timestamp: April 01, 2021, 09:06:02 pm
content: I have a old litz wire inductor, The coating is not 100% good, there is a few strands of wire that are loose on the outside.The device is said to be sealed with 'synthetic varnish'.My go-to for a new device is q-dope which I make with ethyl acetate. Is this safe on 'synthetic varnish"? Otherwise my next choice was transparant epoxy.Its not a dip, just corrections along the surface.I did this to loose wires before, but never a litz wire, I am worried it will melt the insulation and short it out. It is made in 1962it is a general radio product

author: jpanhalt
author_rank: Super Contributor
timestamp: April 01, 2021, 09:34:54 pm
content: I have never come across any magnet wire where the insulation (enamel/varnish) was soluble in ethyl acetate. The silk(?) around the individual Litz wires is not soluble either. That experience includes old wire that had to be scraped or chemically removed and more modern "solderable" insulations.

author: coppercone2
author_rank: Super Contributor
timestamp: April 01, 2021, 10:26:10 pm
content: alright then a thick q-dope sounds like it will fit the bill for the repair with minimum effect
Cobra 240.1 HS E/S - Page 1
Forum section: electronics / repair

author: Loid
author_rank: Newbie
timestamp: May 21, 2024, 11:03:08 am
content: Hello i have problem with my shredder,that make strange noise and the chain "jump" on the gear. I also post a video how its looks like. I already replaced chainhttps://youtu.be/JTIxEWEjpWY?feature=shared

author: Haenk
author_rank: Super Contributor
timestamp: May 21, 2024, 11:35:48 am
content: Judging by the pictures, there is not enough tension in the chain. Jumping occurs when either the gear teeth are worn or the chain does not have enough tension. Usually, there has to be either a chain tensioner, or some adjustment mechanism. There never should occur a slip in the chain driven, as this will then certainly damage the chain and the teeths.Maybe check for wear on the chain as well, these chains can lengthen over time and then need to be replaced.
Coemar Infinity ACL - moving head stage light PSU issue - Page 1
Forum section: electronics / repair

author: stigwurx
author_rank: Contributor
timestamp: April 26, 2023, 12:44:28 am
content: To whom may read ,hi . So this light arrived with sparks shooting out of the NTC from both sides , which didn't bode well . The PSU is 200w 20v@0.5A and 40V@4.5A output . Apart from the NTC I found the IRFPC50APBF mosfet and the diode after it both died shorted . Replaced the deceased components but the only sign of life in the PSU was the main bulk capacitor warming slightly.Replaced the ICE1PCS01G (Power Factor Correction controller) , the UCC3804D ( PWM controller ), the optocoupler and the bulk capacitor . Powered on and the bulk cap promptly proceeded to pop , shooting both magic smoke and sparkles out through the vent in the side.As I had the parts I went and replaced the BD711 , SPP06N80C3 , all of the smt transistors and the new dead capacitor . Switched on briefly and i could hear the hiss beginning from the replacement cap , switched off and yes she was heading towards warm.So all rounds have been expended from the parts cannon , the passives on board tested fine. The transformer looks and smells fine, didnt heat up , metered the two secondary windings and the primary but as this in an SMPS transformer I'm in the dark about how to evaluate it .Now I'm left with assuming the only irreplaceable component is the problem , i.e. the transformer , in which case the PSU is toast and that unit is also no longer available as far as I have found .So other than some short within the primary winding (which is the conclusion I'm tending towards) are there any other reasons which would cause the cap to blow ? Is there a method to test the transformer off of the board to verify whether it is dead or not ?Any suggestions deeply appreciated , I have no schematic to work with so I included a couple of pics of the board instead.Thanks for reading this far ,Regards.

author: Vicus
author_rank: Regular Contributor
timestamp: May 07, 2023, 11:38:22 am
content: The main bulk cap (only 400v?) can fail is for a sustained inverted voltage (soldered backward?) or for an overvoltage (massive or for a log period). The PFC goal is to raise (with a specialized boost converter) the main rectifier voltage slightly over usual voltage (main voltage RMS * 1.4). The pfc IC have a voltage feedback witch is necessary. If something fail in the loop I suppose the cap could explode for overvoltage. This scenario skerries me but it never happened to me.
coffee machine - Page 1
Forum section: electronics / repair

author: m3vuv
author_rank: Super Contributor
timestamp: November 30, 2019, 09:34:42 pm
content: Hi all ive a coffee perculator to look at for a friend,long story short,the heating element relay wont pull in,its a 12v one,from what i can see its powered from the mains via a few diodes and caps,if i remove the relay from the board the 12v feed to it switches from the control board ok,if i send the on signal to the relay pcb pads then conect the relay it pulls in ok,but it wont switch on if i connect it before sending the on signal,ie send the on comand then connect the relay and it pulls in ok,conect it then send the on signal and nothing happens,its like its not getting enough current to pull in,ive tested the caps and diodes,they seem ok,any ideas?

author: shakalnokturn
author_rank: Super Contributor
timestamp: December 01, 2019, 10:18:52 am
content: I always regret it when I accept to look into a coffee machine for someone, one of the rare appliances I'll admit should be thrown awayHow does the voltage at the coil measure in both scenarios?Supply voltage at the zener / regulator, relay on / relay off?The usual culprit is the largish MKT/MKP voltage dropping capacitor on the mains input.

author: SeanB
author_rank: Super Contributor
timestamp: December 01, 2019, 12:39:52 pm
content: There will be a big film capacitor on that board, probably around 470n 250V to 680n 250V. Replace it, along with all the small electrolytic capacitors there, and the capacitive power supply will work again. The capacitors, especially the big film one, only has to be around 10% low before the power supply is unable to deliver the current to hold the relay in, and the small electrolytics the same.

author: m3vuv
author_rank: Super Contributor
timestamp: December 01, 2019, 12:47:41 pm
content: I get 15v on the pcb pads without the relay in the board,ie not connected,thats in the on position and zero in the off position,heres some pics,would the cap you mention be the yellow square one?

author: Gyro
author_rank: Super Contributor
timestamp: December 01, 2019, 12:53:53 pm
content: Quote from: SeanB on December 01, 2019, 12:39:52 pmYes, ten to one, it's the film cap that has self-healed to the point where it no longer has sufficient capacitance to supply enough relay coil current.

author: m3vuv
author_rank: Super Contributor
timestamp: December 01, 2019, 01:40:39 pm
content: well,icwapped the electrolytics yesterday,they were ok,today i changed the film cap,that sorted it,cheers folks,i wouldnt ushaly of bothered with it but it was a friends whos daughter brought it for him years ago,sort of sentimental value!,thats my good deed done for the day!
Coherent compex 200  - Page 1
Forum section: electronics / repair

author: hitecelec
author_rank: Regular Contributor
timestamp: March 24, 2021, 01:37:29 pm
content: Hi AllAre Laser power supply high voltage modules repairable to component level.There is a label mentioning vacuum tested check mark on the HV Module . Can this module be opened?thanks in advanceAnand

author: SMB784
author_rank: Frequent Contributor
timestamp: March 24, 2021, 02:03:42 pm
content: Quote from: hitecelec on March 24, 2021, 01:37:29 pmA more relevant question is are there schematics available to facilitate the repair. In general these power supplies are quite simple units, but there is no guarantee that they havent scrubbed the chip IDs or used unsourceable parts, and in my experience Coherent doesn't provide repair manuals or schematics for anything.Regarding opening the HV module, this seems like a bad practice in general for safety reasons, though I dont know if this particular module is vacuum sealed.

author: perieanuo
author_rank: Frequent Contributor
timestamp: March 24, 2021, 03:52:12 pm
content: can you restore the vacuum level after repair?if you do, open it
Coherent VersaPulse VP error codes - Page 1
Forum section: electronics / repair

author: TmaxElectronics
author_rank: Regular Contributor
timestamp: August 04, 2022, 07:19:16 pm
content: I have just acuired an old coherent versapulse vp laser from a local hospital that isn't starting up. I know the chances are slim but is there anybody here who has service documentation on either the Coherent Medical VEGAS controller board or even the laser itself? I have the operating manual but that doesn't list error codes. The codes it spits out are: 220 499 and 501I'd greatly apprechiate if anybody had some info on these

author: CaptDon
author_rank: Super Contributor
timestamp: August 08, 2022, 12:45:17 pm
content: Is that the model with 4 flash tubes and a rotating mirror or does it have the CO2 conventional laser tubes? I have a friend who was a laser repair technician for a local hospital group. I will see if he has any service manuals for that model.

author: TmaxElectronics
author_rank: Regular Contributor
timestamp: August 09, 2022, 09:00:56 am
content: It's a green flash lamp pumped NdYag. It's from 1997 if that's any helpBut I did actually figure out how to get a description of the error codes. There is a switch labeled "service" on the board, flicking that once the board has gotten stuck at the error code makes it show the gui anyway. That then actually sais what the errors are.Mine happened to have a seized pump and a "power supply did not calibrate" error which came from a broken optical control line to the HVPS. Fixing those two issues seems to have repaired the laser
Coil recommended lacing cord material - Page 1
Forum section: electronics / repair

author: gkmaia
author_rank: Frequent Contributor
timestamp: June 22, 2019, 03:29:00 am
content: Had to replace one of the thermal fuses on my electric motor and for that I had to cut the lacing cord.I could not find the traditional polyester cord anywhere here.But I could find a bamboo cord. And as far as I know back in the day they used waxed linen cords to lace coils.Just want to know if it would be safe to wax the bamboo cord and lace the coil with it.

author: bob91343
author_rank: Super Contributor
timestamp: June 22, 2019, 03:35:23 am
content: I don't know the temperature limit of bamboo. Most lacing is nylon and you should be able to find some of that. Or use cable ties.

author: gkmaia
author_rank: Frequent Contributor
timestamp: June 22, 2019, 03:38:40 am
content: Quote from: bob91343 on June 22, 2019, 03:35:23 amGood idea cable ties will be!!!

author: Stray Electron
author_rank: Super Contributor
timestamp: June 22, 2019, 05:01:02 pm
content: You could use dental floss. You can buy it either waxed or unwaxed, just like lacing tape. DF is smaller than the size of lacing tape that is normally used so you might want to add more wraps and also don't pull it as tight since it could cut into the item being tied.Have you tried looking on Ebay for lacing tape or lacing cord? I bought 32 rolls of it on there about 2 years ago for almost nothing.

author: jdragoset
author_rank: Frequent Contributor
timestamp: June 22, 2019, 09:07:13 pm
content: If you're near the coast, find a net maker.Might get a few yards of nylon no. 6 or 8 for very little.

author: sokoloff
author_rank: Super Contributor
timestamp: June 22, 2019, 09:12:45 pm
content: An avionics shop will likely have the proper waxed lacing cord (or you can buy it from an avionics/aviation supply house).

author: chris_leyson
author_rank: Super Contributor
timestamp: June 22, 2019, 09:19:06 pm
content: Polyester and nylon flat braided lacing cord is available from Alpha Wire in different sizes, either waxed or unwaxed. A 457m reel from RS or Farnell will cost you about £50 though. I still have a small 100m reel of waxed polyester lacing cord that will probably last a life time.EDIT: Thanks sokoloff, avionics wiring bundles are still laced by hand because it's tried and tested and it's reliable. In fact an avionics lacing knot is quite difficult to tie and to my knowledge nobody has made a machine to tie avionics lacing knots.Motor repair shops would be another source of lacing cord.

author: gkmaia
author_rank: Frequent Contributor
timestamp: June 23, 2019, 12:13:15 am
content: Thanks for all the feedback guys! Some nice alternatives in here.
Colbor CL100X — need firmware file (OTA update) - Page 1
Forum section: electronics / repair

author: Yurixbra
author_rank: Newbie
timestamp: September 30, 2025, 09:49:42 am
content: If anyone has a Colbor CL100X or knows where to find the firmware file, please share. I really need it to restore the board after replacing the PHY6212
Colibri Smart Tweezers ST5C (fixed) - Page 1
Forum section: electronics / repair

author: sean0118
author_rank: Frequent Contributor
timestamp: April 27, 2021, 07:18:32 am
content: This one isfixedbut I thought I would make a post in case it's a common issue.I came across some ST5C smart tweezers with a dead battery (3.7V 551430P). It was easy to find a replacement, but even with the battery replaced it would only work intermittently, refusing to turn on at times. It was also heating up and not charging.I powered it up from a bench supply and found that the current was very low when operating but when in fault mode it would draw ~300mA. There was a three pin 3.3V regulator near the USB port which was getting close to 70C and its output being pulled down.Eventually I found the analogue supply AVCC was nearly shorted (~1.5 ohms) to the digital gnd DVSS pin on the MSP430G2553 microcontroller. I ruled out all bypass capacitors etc and ended up removing the microcontroller from the board, the resistance between the pins was still ~1.5ohm. I was just about to give up assuming the microcontroller was damaged internally, however there was a lot of residual flux that had been stuck under the IC, it looked particular crusty between the AVCC and DVSS pins (they are next to each other). Cleaning this off fixed the problem, the resistance between the two pins went to ~700kohm!!!It's back assembled and seems to be working and charging fine now, just shows sometimes the issue is an easier fix than it first appears. It's the fact that it was intermittent that threw me off.tldr: 3.3V rail shorted to GND by flux crustiness under microcontroller.
Com Express Motherboard - No Image - Page 1
Forum section: electronics / repair

author: 2X
author_rank: Frequent Contributor
timestamp: March 14, 2024, 10:17:59 pm
content: Hello, I have a (SOM-5898) Com Express Motherboard. The machine starts and also the CPU fan spins, but I have no image. I have one more identical PCB board with the same PCB part number, so I made a replacement on the bios chip. I took the bios chip from the working PCB and I replaced the chip_1 on the board that has no image and the same thing again.https://www.advantech.com/en/products/9b97accf-0a5b-4166-bf75-38159d579dec/som-5898/mod_d5e189d0-b1a0-43b1-aa7d-256828660dcf

author: 2X
author_rank: Frequent Contributor
timestamp: April 19, 2024, 11:01:34 pm
content: Finally I found the problem... the CPU didn't have supply. There was a Cold Solder Joint on the phase chip which drives the mosfets at CPU. I resolder the chip and now works fine.

author: alm
author_rank: Super Contributor
timestamp: April 20, 2024, 10:09:04 am
content: Thanks for updating us with the solution! This could be helpful if another person runs into the same problem.
COMAX CIOT-D20M IP camera repair, very low current on MC out pin [solved] - Page 1
Forum section: electronics / repair

author: Nifty
author_rank: Contributor
timestamp: February 03, 2023, 03:26:56 pm
content: Hi Everyone!I'm trying to repair an IoT door video camera (COMAX CIOT-D20M), the video from the camera is transmitted, but some time ago the door lock opening function stopped working. The camera has a connector for connecting to a relay output, NC-NO-COM.Relay is 5V DC, current consumption about 40mA, contacts are OK.The relay is controlled by a microcontroller, a fairly standard scheme.At the output, a current-limiting resistor, then an NPN transistor, a diode in parallel with the relay. The diagram is shown below.After the command to open the doors is received, the corresponding output of the microcontroller switches to a high state. If I remove the resistor R1 (no load) - the voltage at the output of the microcontroller is 3.3V.But under load (Q1), the voltage at the base of the transistor drops to 0.7V. This means that the microcontroller is not able to provide even a current of 0.35mA. And the transistor because of this does not provide sufficient current to the relay coil.As I understand it, the output of the microcontroller is somehow damaged. Maybe someone can suggest a trick to deal with this problem.P.S. Without Q1, voltage drops to ~2.5V (on R3).

author: Nifty
author_rank: Contributor
timestamp: February 10, 2023, 03:53:49 pm
content: After some experiments, transistor Q1 (MMBT3904, NPN) was replaced with 2N7002KW (N-FET). Since the N-FET is voltage controlled, the problem is solved - the relay control works again.
COMMAX Intercom Board Repair [Not Opening the Door] - Page 1
Forum section: electronics / repair

author: hesam.moshiri
author_rank: Regular Contributor
timestamp: January 09, 2025, 01:51:04 pm
content: COMMAX Intercom Board Repair [Not Opening the Door]YouTube:https://youtube.com/shorts/XMnbE7OXqBc

author: MathWizard
author_rank: Super Contributor
timestamp: January 09, 2025, 09:18:02 pm
content: Compared to say a modern thermostat, it sure has a lot of electrolytic caps, it that for the audio ? What else needs so many, some step down regulators, what all else ?

author: floobydust
author_rank: Super Contributor
timestamp: January 09, 2025, 09:38:39 pm
content: I would check the SMT fuses. Door solenoids and their wiring can get shorted out.FS1 "FC" near the relay, FS2 by CN1? etc. pic is too fuzzy to see them all. They are green.Which connector goes to the door solenoid?

author: hesam.moshiri
author_rank: Regular Contributor
timestamp: January 15, 2025, 09:47:43 am
content: actually I repaired the thing and that's why I provided a link to the YouTube video to share my experience. the first 4Pin connector from the left goes to the door. the problem was not solenoid
Common resistor/capacitor failures in PC equipment.  Why? - Page 1
Forum section: electronics / repair

author: viper
author_rank: Regular Contributor
timestamp: October 09, 2025, 07:48:24 pm
content: I am sort of just poking for any experienced with modern SMD PCB failure modes. As I am working up a PCB design/circuits, I stumble into these PC repair videos, and what really stands out is nearly random resistor or cap failures that usually fail dead short. Many I see look like just decoupling caps, or other odd failures. It makes me wonder if lesser quality components could be at issue, or if design margins are just being pushed to the limit? Or maybe some of this stuff is hidden ESD type events?I guess I am going down a rabbit hole of potential failure modes and how to avoid them. I guess I was expecting things like mosfet and regulator type failures, but seeing a lot of passive failures that I would think would be insane cheap to overbuild.

author: thm_w
author_rank: Super Contributor
timestamp: October 09, 2025, 09:38:56 pm
content: Failed MLCC is common.Failed resistor is not very common.MLCC are fragile, heat sensitive, etc.https://eurotronix.com/en/news/practices-and-solutions-to-prevent-mlcc-fracture-damage/https://ntrs.nasa.gov/api/citations/20240003605/downloads/Teverovsky-20240003605.pdf

author: wraper
author_rank: Unknown
timestamp: October 09, 2025, 09:44:04 pm
content: Quote from: thm_w on October 09, 2025, 09:38:56 pmI would not say it's not common. 1206 break in half quite often.QuoteUsually poor engineering. Placing MLCC, especially large ones, near mounting holes. For example on Raspberry Pi 2, 3, 3+ it's always the same capacitor that fails despite there being 8 or 7 of the same type on the board. Two of them even in parallel to a bad one, and they never fail.
¿Cómo reparar un multímetro Fluke 77? - Page 1
Forum section: electronics / repair

author: rhmira
author_rank: Newbie
timestamp: June 04, 2021, 04:21:51 pm
content: Estimados.Junto con saludarlos, les cuento que tengo un problema con un Multímetro digital Fluke 77, el cual por accidente se utilizó para medir la tensión en una cerca eléctrica para separar ganado, durante esa operación, al parecer, se dañaron las escalas de resistencia y medición de continuidad. Colocando el selector en la escala de Ohmios no se estabiliza la indicación, colocando el selector en la escala de continuidad, el multímetro emite un sonido agudo y se queda ahí, he revisado elemento por elemento, del circuito, no encuentro ninguno averiado aparentemente ¿quisiera saber si alguno de los miembros del foro ha tenido experiencias con este tipo de problemas o pueden recomendar a alguien que nos pueda orientar al respecto?Saludos cordiales.