hybridfree/eevblog-posts huggingface dataset:
Levitating light bulb, with a sound problem - Page 1
Forum section: electronics / repair

author: therwp
author_rank: Contributor
timestamp: October 30, 2022, 07:03:01 am
content: A 17-second video showing the problem:. The first five seconds were videoed shortly after setting up the light. The rest of the video was captured about an hour later.I bought the pictured levitating light bulb piece a couple of years ago. When the levitation effect is first started, the light and its 'stand' are silent. Invariably, however, after some time, the stand starts to emit a high-pitch sound, which varies depending on the location of the light bulb.The problem existed from day one, and when I notified the vendor, they immediately shipped a (silent) replacement... but I still have this noisy version, and I was recently wondering what the problem is, and if it's something that I could fix.Ideas?

author: shakalnokturn
author_rank: Super Contributor
timestamp: October 31, 2022, 11:14:55 pm
content: Usually a coil loosening up when hot.
Lexicon PCM70, replace rom for firmware update - Page 1
Forum section: electronics / repair

author: Vicus
author_rank: Regular Contributor
timestamp: May 03, 2025, 05:56:58 pm
content: So, I have an old Lexicon PCM70 wich I want to replace the old EPROM with a different firmware version. I can't fine any EEPROM that should work in place of the originaly 2764, 27128 and 27256. I did buy some AT27C256R that are non erasable, correct? And now the question is shoud I write 2 or 4 time the originale image to get a 256kb from the original 64 and a 128kb image?This is the link to the service manual:https://www.vintagesynthparts.com/wp-content/uploads/2018/01/LEXICON-PCM-70-Shematic-Diagram.pdfI want to be shure because the EPROM are quite expensive and they are not erasable.Thanks.

author: floobydust
author_rank: Super Contributor
timestamp: May 04, 2025, 10:16:41 pm
content: I did ask a PCM70 expert. There are three EEPROMs. DSP micocode (2764), Master Z-80 (27128) and Slave Z-80 (27256).The PCM70 is pretty maxxed out of memory, the one Z-80 has to copy 8KB of extra code and presets to the other Z-80 RAM. So it would not be easy to add firmware if that is what you want to do.His advice is use half a 29F010 (32 pins), just ground the extra address line and jumper wires for the extra pins.Or use it with an adapter board. Don't cut up the original board PCB traces.

author: Vicus
author_rank: Regular Contributor
timestamp: May 05, 2025, 07:24:49 pm
content: Nothing special, I just want to make it work. I knew that my english is not so good.Thanks for the effort to asking.

author: floobydust
author_rank: Super Contributor
timestamp: May 05, 2025, 07:54:59 pm
content: You can get a TSOP32 to DIP-28 adapter PCB atOSHPARK, design onSystem11 Blog.These are used in arcade games to replace the ROM's.
Lexmark E260 usb data lines shorted to ground  - Page 1
Forum section: electronics / repair

author: NickyYTSRB
author_rank: Newbie
timestamp: July 23, 2019, 09:23:15 pm
content: My printer is not getting recognized via usb and i decided to measure continuity between d+ and d- and both are shorted to ground. There is capacitor parallel to ground pn both d+ and d- and after that series resistor that leads to main soc. Data lines coming from the soc are shorted to ground. If the resistors and capacitors on data lines are faulty what is the chance of soc being okay with data lines. Soc boots normally and diagnostic paper prints when requested. Is ltp worth using in 2k19? Can i still get printer info and set toner thickness and etc via ltp same as via usb? Im still a 18yo kiddo and i have no idea if that printer to pc communication via ltp can transfer such data about paper jam and etc... I will tru to desolder resistors and capacitors to get data lines from soc floating and measure it again.

author: KD4CCF
author_rank: Contributor
timestamp: July 24, 2019, 04:26:11 am
content: If you're in the US, you can get a refurb 90 day warranty unit for $110 shipped to your door. Has network connectivity too.(no affiliation)https://www.ebay.com/itm/333263311168

author: Chriss
author_rank: Frequent Contributor
timestamp: July 24, 2019, 05:49:45 am
content: Hi!Most of time there is sitting somewhere near the usb connector prptective diodes and esd protective IC which is also some type of diodes.I relaired many times this kind of problems on usb devices.First make the D- and D+ lines clean grom any protection parts and then check if it is inshort.Sent from my SM-J500F using Tapatalk

author: NickyYTSRB
author_rank: Newbie
timestamp: July 24, 2019, 10:23:27 pm
content: Well guys sadly it's shorted inside soc. I hope that parallel port still works. Removed capacitora and resistors and no change.

author: Chriss
author_rank: Frequent Contributor
timestamp: July 25, 2019, 06:33:27 am
content: Can you please post a picture about the region on the pcb where the problem exist?Sent from my SM-J500F using Tapatalk
Lexmark E350D only attempt to start - Page 1
Forum section: electronics / repair

author: nonkapo
author_rank: Contributor
timestamp: May 04, 2023, 12:46:44 pm
content: Good day all. Here we have an old Lexmark E350D which failed after power surge. Now it attempts to switch on, and than get off in a matter of half second. I open the smps as i suspect it. Doing the visual inspection does not show anything. The relay just quickly switch on and off. On the hot side up to the rectifier and capacitor looks ok. Cand get any info on the pwm chip(looks they are two - fps0001 or so). Dont know how to continue. Any doubts? Thanks.
Lexmark ms812dn network card broken - Page 1
Forum section: electronics / repair

author: sunfire
author_rank: Contributor
timestamp: September 07, 2020, 12:50:14 pm
content: Hello,I'm (trying to) repair a Lexmark MS812DN printer which does not connect to network. The network card status on the operator panel always shows disconnected. I tried multiple cables, multiple switches, tried to force a lower speed and duplex on the network port (on the switch), updated the firmware, nothing works. I took the mainboard out of the printer (the network card is onboard) and the physical connector port seems to have the magnetics builtin, it's made by PALCONN (part number RJT-11UC1F-G13). The network PHY chip is made by Marvell 88EC068, i attached a picture taken with my phone. I measured the resistance between the connector pins on the PCB and I'm intrigued by the results : the resistance between all the four pins of pairs 1 and 2 (connector pins 4, 5, 10, 11) is around 0.5 - 0.6 ohms, the resistance between all the four pins of pairs 3 and 4 (connector pins 2, 3, 8, 9) is also around 0.5 - 0.6 ohms. I was expecting the resistance between the connector pins 10 and 11, 4 and 5, 2 and 3, 8 and 9 to be low because I'm measuring the primary side of the transfomer in the connector but I wasn't expecting the resistance between all the four pins 4, 5, 10, 11 and 2, 3, 8, 9 to be low (i.e. I wasn't expecting the pairs to be connected to each other).Is this normal ?I removed the connector from the PCB and the resistance on the PCB pads looks to be what I expected : between the pins 4 and 5, 10 and 11, 2 and 3, 8 and 9 it's ~ 11.3 kohms. However, when comparing the resistance between pins 2 and 8, 3 and 9 (around 600-700 kohms) to the resistance between pins 4 and 10, 5 and 11 (around 1.6 Mohms) there is quite a bit of difference. Is this suspicious ?I'm beginning to suspect the printer was connected to a PoE switch and this may have burned the magnetics in the connector and/or the network PHY chip.Do you guys know of any sources where I can buy the connector and the Marvell PHY chip ? Preferably in Europe (I'm from the Czech Republic).The only sources I found for the connector are the big players in US (Digikey, Mouser, etc), i found nothing in EU.The Marvell PHY chip is even more unobtainium, I only saw it in the electronics trade markets in south east Asia (and they want a minimum order of 100 pieces).Thank you for the help and sorry for the long post
Lexus Nakamichi car audio Japan? - Page 1
Forum section: electronics / repair

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: May 21, 2024, 11:53:45 pm
content: Lexus had Nakamichi in several year/models of vehicle.Is Nakamichi corp. still around in Japan, is it posiable to get service manuals or info now?I am refering to actual manuals on the units like the head units and amplifiers mainly.As in C740ULOA, C724ULOA, B336ULOA, B338ULOA, B330ULOA, B324ULOA and othersI have bought some before but these were lost at another shop that was when Nakamichiwas in the US.Jeff
LG 1510S Monitor Issue - Page 1
Forum section: electronics / repair

author: FercHeliX
author_rank: Newbie
timestamp: January 28, 2022, 02:03:23 pm
content: HiThere's this old LG 1510S LCD Monitor that had 2 issues, one with inverter board and one with image display (mainboard maybe), the issue with the inverter was that when i turned it on it goes off after 1 or 2 secs. and the problem was with the tuner caps on inverter board, after i changed the caps monitor stays on but there's another problem that if I turn it on by the power button, no signal message does not show on the screen, but if I let it stay on and disconnect by the power cable and connect it again the no signal message will appear, and one more thing...the 12V power is 17V before i turn on the monitor but after turning it on it will drop to 12 volts, and about 5 volts to main ... I have 5 and 4.3 and 3.3 and 2.5, the 4.3 is on one leg of regulators on mainboar instead of 5 volts... souldn't it supposed to be 5 volts on the v in of regulators and 3.3 and 2.5 on Vout ?!please help ... thanx alot.
LG 23MP65HQ monitor Repair - Page 1
Forum section: electronics / repair

author: paulossant
author_rank: Newbie
timestamp: May 03, 2019, 05:37:59 pm
content: Greetings members, this is my first post here. Recently I found a Monitor LG 23MP65HQ but there is a problem with the main board.I ordered another one from ALIexpress and received a busted oneSo I'm replacing the caps and measuring the signals.. trying to find the problem.At the 5V5 pin I got 2.5V, so I'm trying to fix that for now..Anyone can point me to a service manual? I cannot find anything on Google..Best regards,Paulo dos Santos

author: PKTKS
author_rank: Super Contributor
timestamp: May 03, 2019, 05:48:28 pm
content: loosely fast best matchhttps://elektrotanya.com/lg_chassis_ld93a_m2362d_pzl_sm.pdf/download.htmlPaul

author: paulossant
author_rank: Newbie
timestamp: May 03, 2019, 06:09:54 pm
content: Thank you for the answer, but it doesn't suffice my needs.I'm trying set parallelism between the two boards I have.In the old one I sucessfully measured the 340kHz PWM signal from the APW7301 BuckConverter, that provides the 5v.I'm trying to figure out the same signal but the Ic is below a metal case for the hdmi and vga connectors. The inductor with the same label as the old (L102) receiving the pwm signal is only getting a stange signal(See Atachment)Thank you so much

author: Rasz
author_rank: Super Contributor
timestamp: May 04, 2019, 04:08:53 am
content: how about powering it from lab supply to check if it will work at all?
LG 24EB23 Monitor Intermittently Restarting - Page 1
Forum section: electronics / repair

author: 3dp
author_rank: Newbie
timestamp: February 28, 2025, 06:16:17 pm
content: Hi,I am trying to repair an LG 24EB23 monitor. The monitor was restarting from time to time, and this was happening more and more frequently, so that the monitor was no longer usable. But it works in between of the intermittent resets. Of course, I first suspected the power supply unit, especially the capacitors. I unsoldered them to measure the ESR but they are all ok, nevertheless I replaced a 680uF capacitor on the output side because this is probably the most critical. Since the power supply delivers 12V and 2.3A internally, I have now completely replaced it with an external 12V power supply, but nothing changes. I would therefore rule out the power supply unit.It is not related to the video sources or cables, the problem occurs via DVI as well as via display port from different devices.On the logic board there is a 5V switching regulator and a 3.3V and 1.2V linear regulator in one chip (APE8839AMP-C). There is also a 40V switching regulator for the LED backlight.With my measurements, I can see quite a lot of ripple on the 3.3V and 12V lines (AC coupled oscilloscope screenshots of how it looks when the problem occurs attached, the yellow trace is 12V the blue one is 3.3V, but over long wires that I routed out of the monitor, which might pick up other noise). However, the capacitors on the logic board are also ok, and the 3.3V and 1.2V rails only have ceramic capacitors anyway. The effect when the problem occurs is that the load drops (e.g. the backlight goes out with it). So voltages slightly change because of the load change but I think that is just a result of whatever makes the main controller power cycle. I also resoldered all pins of the main controller IC and the pins of the voltage regulator just in case, but that didn't help. Turning down the brightness also does not change anything, so I don't think it's related to the 40V circuit, but I didn't rule it out completely yet.The 5.6 Ohm (I measured around 6 Ohm, I think it is green blue gold from the color code) through wire resistor above the linear regulator gets relatively warm, 2V are applied here during operation, so it consumes about 0.7W. The APE8839AMP-C also gets a little warm, but not very much. On the other hand, this is a power resistor, otherwise it would not be so large, so it is to be expected that power is consumed there.I have a small (very low-resolution) thermal camera, with which I could not detect any other real heat sources (also not with my finger).Has anyone ever had a similar problem or perhaps even the same problem with this or a similar monitor? I suspect the APE8839AMP-C might be at fault (unfortunately I don't have one of these on hand, could only bodge in two independent 3.3V and 1.2V regulators), but with the multimeter the outputs actually look good at both 3.3V and 1.2V.
LG 32LG5700: white LCD screen, menu hardly readable - Page 1
Forum section: electronics / repair

author: mspreuw
author_rank: Newbie
timestamp: August 25, 2021, 08:03:16 am
content: LG 32LG5700: white LCD screen, menu hardly readableThe LCD screen of our LG 32LG5700 TV suddenly turned white. For instance the options menu is readable, but very difficult (dark room needed).How can I identify the cause of this or does someone have an idea what is causing this?I pulled the back cover off and cannot see any burned electronic components on any PCB (see picture).Thank you very much in advance.Matthi

author: shakalnokturn
author_rank: Super Contributor
timestamp: August 25, 2021, 10:08:24 am
content: Most likely is a problem on the T-con board.First check LVDS cable and that required power supplies are reaching the T-con.

author: mspreuw
author_rank: Newbie
timestamp: August 25, 2021, 10:45:00 am
content: Thanks for your reply.Can you indicate or point out (on the picture) which is the LVDS cable and the T-con board?Any tips on how to check if the power supply reaches the T-con board are welcome.E.g. check for this voltage on these pins.Thanks!Matthi.

author: PKTKS
author_rank: Super Contributor
timestamp: August 25, 2021, 11:49:10 am
content: Quote from: mspreuw on August 25, 2021, 10:45:00 amIt looks like you have not very much experience w/that kind of panels..The TCON is shielded and you need to remove the shield to see board.The left board is the CCFL inverters and high voltages are present thereDO NOT POKE AROUND CLUELESS...The reason may be a defective bright controller or just the cables,TCON is complex board and LVDS signals are also complex to inspect..Paul

author: mspreuw
author_rank: Newbie
timestamp: September 06, 2021, 01:51:43 pm
content: Thanks for your reply.Where can I buy a replacement LVDS cable?Is the bright controller on the TCON board? Then I need to replace the whole PCB.Thank you.Best regards,Matthias
LG 37LF2500-ZA - Display only showing a few horizontal lines - Page 1
Forum section: electronics / repair

author: NaLogo
author_rank: Newbie
timestamp: May 02, 2020, 07:34:23 am
content: Hey everyone!I'm somewhat new to repairing things but I'd love to see if I can, with your help, get this TV working properly again.This is a 10-year-old LG 37LF2500-ZA and the issue we're looking at is that the screen only shows a few horizontal lines that look like... remains of the OSD.I've checked, cleaned and re-seated the ribbon cables connecting the mainboard to the display driver board as well as the ones connecting the display driver board to the display - but that didn't help.Replacing any of the boards or the display is probably not worth it as I can most likely get a similar TV used for a lot less money... so I'm kind of hoping that some of you have an idea that would not involve buying new boards.Edit: Okay, I could buy a new display driver board. They cost next to nothing on AliExpress. Would that be worth it or is it more likely that the display is just screwed up?

author: pe0hm
author_rank: Newbie
timestamp: May 11, 2020, 09:16:05 pm
content: I have had the same problems with a similar LG. I swapped the driver board but the problem stayed. So I think this problem could very well be in the panel itself.

author: NaLogo
author_rank: Newbie
timestamp: May 12, 2020, 06:04:05 am
content: Quote from: pe0hm on May 11, 2020, 09:16:05 pmAh damn.Well, I've bought a display driver board when I posted so I'll give that a shot anyway. I'll update this with the results.
LG 42LG61YD LCD TV takes several cycles to power up - Page 1
Forum section: electronics / repair

author: 5m3g_head
author_rank: Newbie
timestamp: March 25, 2025, 09:05:36 am
content: Hey Team,Ive been messing with this LG TV and Im not sure the next step.The fault is - Turning the TV on.. you hear the power up sound, the backlight comes on, but often the LCD stays black.. after a few on/offs it will boot up and work. Seems worse in the cold weather.Ive spend my time on the PSU, there were a couple of Caps that were out, but nothing to bad. I replaced them anyway. Also resoldered some joints on the hot spots. Ive measured the voltages when its booted and when it hasnt and they are the same, Im pretty confident the PSU is OK.Can anyone advise me on what to look at next ? Im wondering if its a dry solder joint, but Im not sure which board to look at.Any advice is welcome.cheers.

author: Kharn_the_Betrayer
author_rank: Contributor
timestamp: March 25, 2025, 02:04:18 pm
content: Sounds like it could be an issue with the LCD controller. I'd pay special attention to the LVDS connection since the backlight seems to work fine.If you don't have it already, you can find the service manual for the TV here (https://www.manualslib.com/manual/689085/Lg-42lg61yd.html#manual). It might give you some ideas.

author: DaJMasta
author_rank: Super Contributor
timestamp: March 26, 2025, 04:50:25 am
content: May be worth checking caps or regulator outputs on the main board too. Just had a repair of an intermittent boot up fault (seemed like it wouldn't boot until it was warm and then would reliably boot) that was old, dry electrolytic caps on the main rails of the motherboard even though the power supply board and other boards were fine.

author: tom66
author_rank: Super Contributor
timestamp: March 26, 2025, 10:38:40 am
content: Check the voltage to the T-con board, there's usually a fuse near the input. This is usually 12V or 15V. If that is good, time to take pictures of the T-con board and check the voltages there.It's also worth eliminating the possibility of the main board being defective, you could try disconnecting the T-con board after the set has powered up with the main board, waiting for the T-con and LCD panel to cool down, and then connecting it whilst running. If it comes back immediately I'd be minded to consider the main board as the fault.

author: 5m3g_head
author_rank: Newbie
timestamp: March 26, 2025, 07:14:33 pm
content: Thank you all for the sugestions. I'll get stuck into this on the weekend and see what I discover. Cheers.

author: keymaster
author_rank: Regular Contributor
timestamp: March 28, 2025, 10:11:02 pm
content: i have the same tv with the same problem , the solution was to change all the (20+) caps from the board in the middle of the tv (https://www.ebay.co.uk/itm/325617411824) .I don't know which cap was the problem , but the problem disappear.

author: 5m3g_head
author_rank: Newbie
timestamp: April 04, 2025, 08:40:30 pm
content: Thanks !I just removed that board.so I will check out the caps.I have an ESR meter, so I'll see if I can locate the faulty caps.Cheers.
LG 43UJ750V TosLink transmitter - Page 1
Forum section: electronics / repair

author: perdrix
author_rank: Frequent Contributor
timestamp: July 24, 2023, 02:59:41 pm
content: My wife fell and knocked the TV (LG 43UJ750V) off its stand. AFAICT the only damage is the TosLink transmitter socket for digital audio out.It is a vertical format connector with pins on a 0.1" x 0.3" grid and is 0.5" high. It has no identifying marks other than a letter S underneath.Can anyone put a part number to this and where could I buy it?ThanksDavid

author: perdrix
author_rank: Frequent Contributor
timestamp: July 24, 2023, 03:52:14 pm
content: It would appear it has an LG part number at least: EAG37842012Now if can only find one in UK!!!David

author: wasedadoc
author_rank: Super Contributor
timestamp: July 24, 2023, 04:18:54 pm
content: Those things are fairly generic. Any transmitter with the same physical shape should work.

author: perdrix
author_rank: Frequent Contributor
timestamp: July 24, 2023, 04:44:50 pm
content: Indeed so, the problem is that most are horizontal format - couldn't find any vertical ones in my distributor searches.

author: perdrix
author_rank: Frequent Contributor
timestamp: July 25, 2023, 12:56:56 pm
content: Well LG UK were less than helpful.QuoteI could only find the original p/n (EAG37842012) from suppliers in USA and Poland. Luckily I found Spares2Repair in UK who had several parts with the right form factor and pinout. I just ordered one with the Vestel brand:https://spares2repair.co.uk/vestel-toslink-socket-fibre-optic-transmitter-pbt-vert-rohsThere was an LG one with a slightly different p/n EAG37842001 but that was 3x the price!!

author: perdrix
author_rank: Frequent Contributor
timestamp: August 02, 2023, 12:46:09 am
content: But of course that crow is really tasty - the Vestel part didn't have the same lead spacingSo I had to order the LG part:https://spares2repair.co.uk/lg-toslink-socket-jack-fibre-opticHo-hum
LG 50 PA 6500 - Page 1
Forum section: electronics / repair

author: squigley
author_rank: Contributor
timestamp: January 27, 2020, 07:15:35 pm
content: A friend messaged me about their LG Plasma TV, says it's "doing this", and inlcudes photo showing the "no signal current input" message on the screen, but it's black and white and half of it's missing, and a jagged washed out mess. Pic included.My guess is that it needs a buffer/sustain board replaced? Anyone seen anything similar?
LG 55EG960T OLED on Standby only (PLEASE HELP) - Page 1
Forum section: electronics / repair

author: AgentNovac
author_rank: Newbie
timestamp: June 20, 2020, 07:32:47 pm
content: Hi, i have an LG 55EG960T OLED TV and it doesn't switch on. The standby light is present and blinking when I press the button on the remote. What could this be?here are some voltages. I think this could be a power supply issue but what you think. (see attached pic)CONNECTOR 1: Goes to the Primary PSUPin 1: 253v2: 253v3: 253v4: 253v5: -6: -7: -8: 5v9: 5v10: 5v11: 5v12: -13: -14: 19vCONNECTOR 2: Goes to the motherboardPin 1: GND2: 0v3: 0v4: GND5: 0v6: 0v7: 0v8: GND9: 3.5v10: 3.5v11: 0v12: 0vCONNECTOR 3: Goes to the TCon BoardPin 1: GND2-8 has 0v9-14: GNDWeird thing, when I unplugged the tv and pressed the power button on the remote the LG logo was flashing for like 1min then it went off.When I plug in the tv I don’t see anything lit on the logo, only when I press the power button on the remote the light comes on but flashing for around 1min then goes off.
LG 55LB620V TV brightness not stable after LED change - Page 1
Forum section: electronics / repair

author: nmid
author_rank: Newbie
timestamp: October 02, 2022, 05:18:00 pm
content: Hello, a few LEDs were burnt out on my TV, so I replaced all of them with new strips.Unfortunately, after reassembly I noticed that although the backlight is now working again, it is not stable. The top left LED bar is getting brighter every 2 seconds and then normalizes again.Here is a video:https://giant.gfycat.com/QuerulousAmusingGossamerwingedbutterfly.mp4Is my assumption correct that it must be the driver and not the strips? Could it be the half burnt out LED strips caused the driver to have a defect? Do any of you have a suggestion what I could try, otherwise the 70€ for the new strips just to have a defective TV would hurt me a lot.Thank you very much for any help.

author: eurgenca
author_rank: Regular Contributor
timestamp: October 02, 2022, 05:26:27 pm
content: Could be first led on strip damaged.? Top left corner seems to be dark.

author: nmid
author_rank: Newbie
timestamp: October 02, 2022, 05:36:36 pm
content: Thank you for your reply.I do not believe, so I tried the LEDs when the LCD was still off and all LEDs worked.But because of your post, I took another picture/test and noticed that on the left side of the screen the picture is a little stripy. So I suspect it might actually be the LCD itself and not the LEDs. I will try reconnecting the ribbon cables, but I suspect I might have damaged something when dissembling, which would be a huge disappointment.https://giant.gfycat.com/OrneryCalmCalf.mp4It's not really noticeable because of compression and refreshing.

author: nmid
author_rank: Newbie
timestamp: October 03, 2022, 01:27:12 am
content: So I am pretty sure it is not the LEDs, when unplugging the left ribbon it does not change brightness and I don't see it from the back as well.So, anyone has any ideas what I could try? I have tried swapping the ribbon cables, pressing all ribbons and components on the signal board without success. The flicker is in fixed time intervals (~2s).I appreciate any help. Thanks.

author: nmid
author_rank: Newbie
timestamp: October 03, 2022, 01:29:04 am
content: One picture is wrong.

author: nmid
author_rank: Newbie
timestamp: October 05, 2022, 03:02:58 pm
content: I have an oscilloscope if that helps, but not much experience with it.
LG air conditioner - Inverter - DC peak current error - Page 1
Forum section: electronics / repair

author: Libas
author_rank: Regular Contributor
timestamp: July 26, 2022, 02:49:45 pm
content: Hi,Im looking for some help with troubleshoot (PCB repair) of my LG air conditiner. I have already tried quite a lot of things but unfortunatelly without any effect. Still cant find source of DC peak current error (error no.6).At this moment Im out of new ideas so I will appreciate any kind of help which could move me another step forward. Im also still not familiar with purpose and working principle of some PCB components and clarification of those components could be helpful for me.I have available much more documents + photos if somebody is interested in and ready to dive in deeper. Full service manual also available but not able to upload here due to file size limit.

author: Libas
author_rank: Regular Contributor
timestamp: July 26, 2022, 02:50:23 pm
content: ...

author: Libas
author_rank: Regular Contributor
timestamp: July 26, 2022, 02:53:28 pm
content: ...

author: Libas
author_rank: Regular Contributor
timestamp: July 26, 2022, 03:03:18 pm
content: ...

author: Libas
author_rank: Regular Contributor
timestamp: July 26, 2022, 03:11:03 pm
content: ...
lg cm2460 schematic needed - Page 1
Forum section: electronics / repair

author: Aheld
author_rank: Regular Contributor
timestamp: January 26, 2025, 08:57:11 am
content: Hi Forum,could some one help me with the schematics for lg cm2460dab micro HiFi?Service manual is available but without schematics.Device error is that device is not switching on. No reaction to power switch activities.Power supply seems to be fine, but no signal on the stand by pin and no documentation for this signal available.Thanks in advanced.Axel
LG Flatron W1942S power issues - Page 1
Forum section: electronics / repair

author: geq
author_rank: Newbie
timestamp: July 22, 2019, 08:00:27 pm
content: Hello! I'm troubleshooting an LG Flatron W1942S LCD monitor. It didn't power on, sometimes after unplugging and plugging it back in several times it showed the LG logo for a second or less, and back when it worked the colors were off. I disassembled it and noticed several capacitors were swollen, so I changed all the electrolytic capacitors on the power supply board. Only one capacitor is different now, the 450v 68uF is now 450v 100uF. Now the image quality is better than when it was new.But after being unplugged overnight, when I plug it in, the power button is unresponsive, sometimes with its light on, sometimes completely off. If I unplug it and plug it back in, it immediately begins to work perfectly. Then you can turn it off and on, unplug it and plug it in again, whatever you do it always starts up normally and with a clear image.What should I check?Thank you.

author: tunk
author_rank: Super Contributor
timestamp: July 23, 2019, 11:33:29 am
content: Bad contact somewhere?Could you try with another power cable?Maybe reseat all internal cables (or at least for the power button).Or reflow the soldering of the IEC320 connector.

author: PKTKS
author_rank: Super Contributor
timestamp: July 23, 2019, 05:07:19 pm
content: or plain COLD JOINTS...when you stress the plugs with some moves.. it works againLEAD FREE SOLDER cause this quite a lot in high thermal mass PLUGs.. BTW it also cause some CAPs near by those plugs to crack..usually the mechanical stress of the plug itself is more than enoughto crack the crappy LEAD FREE old joint...Paul

author: mariush
author_rank: Super Contributor
timestamp: July 23, 2019, 07:04:23 pm
content: Sounds like a 5v / 3.3v stand-by issue.Try replacing the electrolytic capacitors on the display board, at least the big one near the connector, i think this is your board :With such old monitors, you have to be careful about the high voltage wires making good contact with the CFL tubes... they can be so hot that the solder blob that keeps wire soldered to those tubs can fall and you get imperfect contact.So, when you try to start the monitor, the backlight controller detects no current drawn by the fluorescent tubes and shuts down. When you unplug/replug or turn on/off you're touching the display enough that the wire could re-make contact and work the 2nd attempt.Resoldering the wires fixes the issue.Not saying this is your problem, but it's not uncommon occurance.
LG LCD TV T-CON Board - Page 1
Forum section: electronics / repair

author: rodrigopires
author_rank: Regular Contributor
timestamp: September 25, 2019, 03:08:27 pm
content: Hello everyone! I have a LG 42LN5200 LCD TV that stoped showing image, it has backlight on, sound and changes channel but no image... I suspect the t-con board is at foult but when looking online for a new part o saw several boards with the same part number (6870C-0452A) but from/for diferrent TV's... My question is what sould i look for? The TV model or the board part number? The same board can be apllyed to diferent tv models?Thank you for you time and knowlage!

author: shakalnokturn
author_rank: Super Contributor
timestamp: September 25, 2019, 09:34:58 pm
content: Board number is more relevant, same T-Con's are used on different models.Before replacing, of course check LVDS cable is correctly fitted.On T-Con board check power is present before and after "F1" fuse.If power is present before but not after, look for shorts on T-con then replace fuse.If power is not present before, look for a defective (P)-MOS on mainboard responsible for power switching.If power is present after, test for other voltages on T-Con on the larger diodes near the inductors.

author: mzacharias
author_rank: Frequent Contributor
timestamp: September 26, 2019, 12:58:59 am
content: First look for a small chip-fuse bad on the existing T-con board. You might get lucky.

author: rodrigopires
author_rank: Regular Contributor
timestamp: September 26, 2019, 12:14:05 pm
content: Thanks for the replies! I will test the fuse and power on the board!
LG LCD tv warm up issues - Page 1
Forum section: electronics / repair

author: Quantumplate
author_rank: Regular Contributor
timestamp: January 28, 2022, 03:56:42 pm
content: It's an LG26LC55 that's been on the blink for some time ie years! Used to get the screen pic attached for about ten minutes, then slowly the working picture would arrive via three horizontal bands that would each start working in turn. After some months though the pic would never arrive. Had some luck replacing a few out of spec caps in the power supply section - there was still a long wait, but the picture would eventually work fine. Now, no pic, just the screen with frozen vertical lines. I've replaced all the caps now bar the two 450v ones on the board. I've also tried two different AV boards - used from ebay, so heaven knows if they were ok to start with, and no change.If anyone can diagnose from this brief description then I'm all ears and very grateful. Should I replace the final two caps on the power board (the 450v ones)? New to this game.

author: inse
author_rank: Super Contributor
timestamp: January 28, 2022, 05:22:57 pm
content: If it is obviously a thermal behaviour, get a hairdryer and cooling spray and start searching for the culprit.

author: BrokenYugo
author_rank: Super Contributor
timestamp: January 28, 2022, 06:00:51 pm
content: I would assume trouble on the TCON board or in the panel itself. You've more or less eliminated everything upstream.

author: Quantumplate
author_rank: Regular Contributor
timestamp: January 29, 2022, 07:50:01 pm
content: Yes, you're probably right about the tcon. I'm trying to remove it but it's got me stumped at the moment. Can't find anything online, do you know the procedure?

author: BrokenYugo
author_rank: Super Contributor
timestamp: January 29, 2022, 09:34:58 pm
content: I've never personally seen this model, it isn't in plain view after removing the back?

author: Quantumplate
author_rank: Regular Contributor
timestamp: January 29, 2022, 10:26:15 pm
content: That's it under a steel cage. Four screws go thru that holding the pcb down, but if I then angle the cage up and try and pull the board out there 's a ribbon cable holding it back, and doubtful if I have room to pull it out anyway.

author: sean0118
author_rank: Frequent Contributor
timestamp: January 30, 2022, 10:28:23 am
content: Similar issue to yours?https://www.badcaps.net/forum/showthread.php?t=23733

author: Quantumplate
author_rank: Regular Contributor
timestamp: January 30, 2022, 11:25:57 am
content: Thanks for the link, interesting.

author: abdulbadii
author_rank: Frequent Contributor
timestamp: January 30, 2022, 11:53:38 am
content: Honestly I'm not knowledgeable on this but readhttps://electronicshelponline.blogspot.com/2013/06/how-to-diagnose-failed-tcon-board-how.htmlif know what it means by video process circuit is than it'd be very helpfful
LG LD330-TA with EAX61124201/16 rev1.3 blowing fuse - Page 1
Forum section: electronics / repair

author: nonkapo
author_rank: Contributor
timestamp: November 03, 2019, 05:30:57 pm
content: Good evening everyone.I'm struggling with this machine some time and cant figure out where's the culprit.The TV went dead after sudden blackout in my apartment(due to improperly designed installations and overload). After discovering the fuse is gone, replacing it and powering through serial bulb all seems fine and i assemble it. I use the TV as a monitor through HDMI port(if that does matter)and it stays non stop on. Two days later it went dead again. Figuring out there is short somewhere i change the two 68uf capacitors, the 0.12 resistors(latest have a sign of burning) and the MOSFEt(mine is a single mosfet version with 13NM60N). I have PWM HS01C but do not manage to find it during the repair and decide to skip replacing it. After the serial bulb test i switch the TV on and in 6 seconds it blow the fuse again. What do i miss(accept for the PWM)? The bridge test fine. no external signs of damage on the rest of the components?!?1? On top i cant find the schematics either(should be in the downloads section but under different name. Please advise.Thanks

author: james_s
author_rank: Super Contributor
timestamp: November 03, 2019, 05:35:34 pm
content: Check the electrolytic capacitors in the power supply, particularly the bulk filter and any others on the primary side. It's common for problems to be noticed after a power failure when the capacitors are marginal, the ESR rises as they cool off.

author: nonkapo
author_rank: Contributor
timestamp: November 03, 2019, 05:40:45 pm
content: Thanks, the bulky one are the one already replaced. Will check the others too.But can i exclude the PWM from the suspects than?

author: nonkapo
author_rank: Contributor
timestamp: November 07, 2019, 06:26:24 am
content: Well, all capacitors look ok as per the ESR, so proceeding to replacing PWM chip. Will update you on the results. Any other advices?Thanks.

author: kosomsk
author_rank: Regular Contributor
timestamp: November 08, 2019, 07:00:33 pm
content: Check PFC circuit, he's can guilty in death capacitors 68uf
LG Oven PCB EBR89296001  - Page 1
Forum section: electronics / repair

author: pletrk
author_rank: Newbie
timestamp: October 24, 2024, 11:45:50 pm
content: I am looking to identify a replacement transistor for LG Oven PCB. The only markings on the transistor are ALYE2 however this doesn't appear to pull up any replacements when I google search this part number.The model of board is EBR89296001. It is the transistor that is driving RLY3 (tip of pink highlighter in pic)Any help would be appreciated.Thanks.

author: fzabkar
author_rank: Super Contributor
timestamp: October 25, 2024, 01:43:22 am
content: Is it KTC3875S-Y ?https://datasheet.octopart.com/KTC3875-KEC-datasheet-492934.pdf(datasheet)ae-pic-a1.aliexpress-media.com/kf/Se76f97a88b9b444db9a2eb58bb189459Z/100PCS-KTC3875-KTC3875-GR-RTK-PS-MARKING-ALG-2SC3875-NPN-transistor-SOT23.jpg(photo)http://markingcodes.com/search/c/aly

author: pletrk
author_rank: Newbie
timestamp: October 25, 2024, 09:24:20 pm
content: Thanks for the response, I am not 100% sure...do you think that one would work work in my application? I am not familiar with how to cross reference these as I don't know the specs for the current transistor.

author: fzabkar
author_rank: Super Contributor
timestamp: October 25, 2024, 10:35:55 pm
content: That transistor is suitable for your application. It switches the relay coil to ground. That would require an NPN transistor, and the coil current would be of the order of tens of milliamps.

author: pletrk
author_rank: Newbie
timestamp: October 25, 2024, 10:38:46 pm
content: Thanks for the information, I will give it a shot.

author: pletrk
author_rank: Newbie
timestamp: October 29, 2024, 10:24:03 pm
content: Thanks for the help with this one, I swapped out with a new transistor and circuit now works.Much appreciated!
LG RL4 (i made a mess) - Page 1
Forum section: electronics / repair

author: elmontador
author_rank: Newbie
timestamp: September 02, 2025, 09:26:37 am
content: Hello i hope someone can help me i made a mess, i forgot that the board still hot and i knock some resistors out of place, i can't find any schematics or any info, i am uploading a picture with the components i need to put in place i don't need the full manual just the list for the resistors and their value(8 in total), if someone can help i'll be thankful

author: coromonadalix
author_rank: Super Contributor
timestamp: September 02, 2025, 10:59:13 am
content: i would try to check the values like r512 up to r518 517 524 r571 573 r5g2 r5c5to see if all the values are the same, sometimes around an mcu you can find tons of same values if say : they are pull ups or pull down, in serial on the mcu control lines etc ...

author: elmontador
author_rank: Newbie
timestamp: September 02, 2025, 01:54:17 pm
content: i don't wanna risc putting the wrong value and burn the MCU or for that matter a gpio, what would be the purpose, for example i measure R503 it as a value of 75ohm and it goes to the TAS5548 so i assume that R5G1 and R5F7 that goes to the same CI should have the same value right ? Wrong i only have one that as the same value, there goes the logic.I have:2 resistors 4.6K1 resistor 33ohm1 resistor 75ohm4 resistors 100ohmI also have a buck converter broken i cannot find the reference but that i know, it produces the DIGITAL 3.3V so no problem there i just get one external and problem solved, but if i start to introduce more variables to a problem i will never know where does the problem came, with out a real reference you always in the doubt if the device doesn't work if its another problem or the resistors. It was a miracle find all on the board and the bench where talking SMD 0201 (0.6x0.3mm).But thanks anyway for your answer, i know you just trying to help, i appreciate you.

author: coromonadalix
author_rank: Super Contributor
timestamp: September 02, 2025, 03:18:23 pm
content: you dont have many choices leftfind another unit, and grab the parts values and rebuild your'sas for schematics ? unless you find them, you're kinda out of luck, some or many DUD websites, or some paying ones ?and maybe if you're patient, you may wait, someone here may chime in to give you thoses needed values ..good luck
LG sk4d repair - component identification - Page 1
Forum section: electronics / repair

author: virusman
author_rank: Newbie
timestamp: September 07, 2022, 04:08:28 pm
content: Hello to everyone.I'm reparing a soundbar from LG, model sk4d.Broken component looks like a dc/dc voltage converter.SMD marking code is AVXK in firs line, and 385 in second line. See attached photo. Any info about this component will be very usefull.

author: fzabkar
author_rank: Super Contributor
timestamp: September 07, 2022, 06:35:41 pm
content: Maybe you can find a service manual for a similar product here?http://www.jordansmanuals.com/default.aspx?Brand=LG&Product=Home%20Theatre%20Sound%20Bar

author: Mario87
author_rank: Frequent Contributor
timestamp: September 08, 2022, 08:14:39 am
content: First question is what makes you think that particular component has failed? What has drawn you to that conclusion?

author: wraper
author_rank: Unknown
timestamp: September 08, 2022, 08:30:11 am
content: It looks overheated as minimum.

author: wraper
author_rank: Unknown
timestamp: September 08, 2022, 08:35:04 am
content: Yes this looks like DC/DC converter. Also marking looks like it should be from MPS (Monolithic Power Systems).

author: wraper
author_rank: Unknown
timestamp: September 08, 2022, 08:38:29 am
content: Device code supposedly is AVX, K is a year and the bottom row is a lot number.EDIT: also I think device number should be somewhere in MP16xxGTF range. Unfortunately many devices in that range do not have a datasheet available and I cannot find photos either.

author: Mario87
author_rank: Frequent Contributor
timestamp: September 08, 2022, 09:45:36 am
content: Quote from: wraper on September 08, 2022, 08:30:11 amActually, after another look, not only does it look like it's overheated I think there is a small crack at the bottom of the number 3

author: wraper
author_rank: Unknown
timestamp: September 08, 2022, 09:57:28 am
content: In the end I think it's likely MP1602GTF-xx (fixed voltage version) with voltage suffix unknown to me but you can figure out it from what it is powering, and checking if there is a feedback divider (for adjustable version) or not. See MP1601 datasheet for pinout and schematic (page 19) as it likely does match. Similar to MP1601 third letter in device code likely indicates voltage suffix.https://www.monolithicpower.com/en/mp1602.htmlChecked many of ICs:Unknown: MP1602, MP1603, MP1614Certainly not:MP1601MP1605MP1606MP1651MP1652MP1653MP1654MP1657MP1658MP1660MP1470MP1476MP1476LMP1477MP1477HMP1479MP1488

author: fzabkar
author_rank: Super Contributor
timestamp: September 08, 2022, 06:53:13 pm
content: I notice that MP9161AGJ (an 8-pin IC) uses the same marking code (AVCy) as the 6-pin MP1602.https://www.monolithicpower.com/pub/media/document/MP9161A_r1.01.pdf
LG Smart TV Blank Screen - Page 1
Forum section: electronics / repair

author: tommwright
author_rank: Newbie
timestamp: October 27, 2019, 11:43:38 pm
content: Hi guys,I have been given a non-functional 47" LG smart TV (LG 47ln575v), the display is blank however the LED backlight is working. There is no obvious damage to the display panel and I assume that it is more an issue with an internal PCB rather than LCD.My first thought was the T-con board inside, and after opening up and some testing, I replaced the board as it was only a small cost. This had no effect and the display is still black.I have tested all of the power supply rails which are perfectly fine, and the backlight comes on which means this is not a power issue. I have inspected all other PCBs visually for damage but I have not spotted any blown caps or obviously burnt-out chips.I have also tried connecting a laptop through a HDMI port which resulted in sound through the speakers, however the volume could not be changed by the control buttons on the TV and also occasionally cut out for a second or two.If anyone has any idea what I should test next I would much appreciate it as I am very much stuck at a dead end currently. Any ideas what the issue could be?Thanks,Tom

author: kosomsk
author_rank: Regular Contributor
timestamp: October 29, 2019, 08:13:00 am
content: Hi! Show measurements from t-con board
LG smart tv motherboard repair fail/ flashing firmware/ schematics - Page 1
Forum section: electronics / repair

author: tbavcevic
author_rank: Contributor
timestamp: November 29, 2022, 09:48:38 pm
content: hi all, i have saved somewhat nice LG 43um7050plf tv from dumpster.it is in good condition and was working but there was no picture other than on screen menu, i was not sure what was wrong but i think it was main cpu issue.since i am somewhat in unknown waters with tv-s i had ordered new main board from ebay thinking easy and cheap fix , but mistake was made and i ordered board for 49um7050plf.when i realized what happened i was still thinking it looks same all same connectors everything looks same from photos it should work right?!but no, when board arrived it became obvious that it has different connectors that go to panel, but luckily i have managed to remove connectors from original and solder them on new pcb, also some connecting resistors were different so i swap those and also some chip i was too lazy to even google what it is that was empty on new pcb. also eeprom was moved from original pcb to new.now tv does turn on and backlight turns on for few moments but then backlight turns off but tv is still on and pulls around 7w from wall, remote works for turning off and on again. there is no weird lines on screen for that few moments but there is also no picture.i am thinking i should somehow flash firmware from old tv and it should work(but how to flash since there is no picture, is it maybe possible to flash over ethernet with like ssh or something) given that there is no mistake with redoing conectors and other stuff new pcb should now be same as original, only i am not sure if cpu is different.if some good soul has schematics for said tv-s, or knows of where to find them it would help a lot.any suggestions for what to do to make it work?thanks for your time and help.