Hello, I finally decided to register here as I wanted to improve my knowledge of electronics repair. Someone gave me a LG Flatron W2243S-PF monitor which turns off after a few seconds and while it is on it makes a high frequency noise. I already opened the thing and replaced some of the caps, but unfortunately still the same issue. I tried something else, and plugged out the upper CCFL connectors (one with red color wire and one with blue color wire).
Door: White_Wax , 14:19:24 comment5, single_zayn_malik_2015, sgr, chhath_puja_song.
With those two disabled the high pitch noise was gone, however the thing still turns off after a few seconds, exactly the same. Later on I tried to also remove the bottom CCFL connectors (so no CCFL attached anymore) now the monitor does stay on, however you obviously don't have an image (I used a flash light, and then I see the screen still being on). With only the bottom CCFL connected the screen still goes off, but the red power led stays on. Any directions with this specifics? I added a picture of which cap I replaced.
Later on I discovered that there was another cap, which I forgot. I still need to buy a component tester (something like M328) so I can actually measure the caps. What I replaced: 3 X 50 V 270 µF (C818, C830, C839) 2 X 10 V 1000 µF (C819, C823) 1 X 16 V 470 µF (C820). I think it must be something with the transformer, because I discovered that the initial issue it has is not that the display turns off, no only the backlight is turning off. Is it likely that the big cap has degraded and not able to supply the voltage anymore? And I also forgot to replace the tiny cap you see just above the big heatsink. I ordered a component tester so I can actually test caps instead of randomly replacing things.
I'm a bit precautious because of the high voltages of the CCFL I read everywhere. Hello MsG, did you solve your problems with this monitor? I have similar issues with the same model, but in my case the backlight is turned off after 0,5s. I did the same as you, I replaced the caps, it didn't help. CCFLs are OK as I have tested the unit with different CCFLs and the same problem arises. Thus the transformer is a good guess but not worth purchasing anew, I suppose.
Did you notice that the service manual you attached is for this model but refers to different electronic boards?What a mess!!! I could't find appropriate schematics for this unit. Retina network security scanner serial number. I would give it a try but I now see that 1/6 of the screen (right, vertically) is not properly addressed, no image and vertical lines. I guess either the TCON card or 1 of the connections to the LCD panel is defective.
There is therefore not much to do with this unit. I will take the PSU put of it for the capacitors but that's all. My purpose was to identify the origin of the problem and I succeeded. But in this case the repair failed.
No worry I still have a couple of candidates for repair in my basement!