Hi everyone picked up this 75inch lg tv has sound but no picture. So far I have disconnected each lvds cable separately from the t con with no change in picture. I have looked at the boards with a thermal camera and the hottest component is the one pictured. I can’t seem to find any information on it online.
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Suppose its a double diode, testing there, hes on a double at the 7:40 mark, meter set to diode mode: https://www.youtube.com/watch?v=0VfSvU1AHfc -
disconnect LVDS had nothing to do with correct testing on LG
you need to access to the panel buffer boards and try disconnect one a time U Ribbon cable where it should be at the middle of each half sideComment
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Thanks for the replies both, the double diode was at fault. Swapped it for a similar one but still the same blank screen. I’m not sure if it’s the tcon or screen at the moment. I believe it had a new main board before I got it.
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How can it be at fault if your problem is still there..Comment
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I tested it and it let current through both ways on one of the diodes.Comment
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One possibility and something that should be watched out for, is maybe someone ordered the wrong mainboard. What can happen is they may order by the silkscreen numbers on the board instead of the numbers on a sticker that is usually on every board AND like our old pal Budm always stated "The silkscreen numbers are just the indicator of the board used before it is populated with other components, once it gets populated it gets the sticker which identifies the specifics of the board"Comment
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Thanks, Yes quite possible, is there a way of checking the screen before I replace any of the boards?
I have disconnected the ribbon cables one at a time with no change to the display but as the above comment stated this is not the correct procedure for an LG.
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Diah had a suggestion in post #3, did you try that?Comment
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We just had a thread with what seems like the same problem, he had a double diode problem, a replacement mainboard fixed the issue, mainboards are tricky and complicated, even some seasoned pros can't figure them out.Comment
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Hi yes tried Diahs suggestion no change. Is it common for the main board to produce sound but no picture?
No replacement boards available at the moment. Not much online about this tv or the boards.Comment
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Yes and no. Sometimes it produces white screen in my experience and replacing it has fixed it sometimes for me. More often then not, replacing the main board on a TV with symptoms like this did not work. But sometimes it did for me.Comment
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This
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correct.. yours T-CON on the panel or at MB let see the whole thingsComment
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ok so you have sound and BL but your yours screen with out image..... did you test the fuse of the t-con F301 if it had 12V on both sideComment
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Hi yes has 12vComment
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this tv is throwing me for a loop. do samsung tvs no longer have the backlight self test feature built into the power supply?
i tested the backlight with my LED tester and it lights up both strips. one of them reads 100v and the other reads 63.7v.
unplugged mainboard from power supply but left backlight plugged in, and then plugged psu wall power in. expected to see backlights light up but see nothing.
according to how ive diagnosed in the past, this would almost always be a bad power supply. replacement power supply was cheap like 20$ from ebay. but still i get not even... -
Hello everyone,
Ive got a UE60KU6079 on the workbench that is giving me some headaches trying to troubleshoot.
The previous owner stated that there had been white dots on the screen which from the description sounded like some lenses fell of the backlight LEDs.
He had opened the TV from the back, trying to get to the backlight, supposedly gave up, reassebled everything and gave the TV to me.
I expected the worst like ripped COF cables or a cracked panel but could not find anything like that yet.
Anyway I still fully expect that there has been something seriously damaged... -
TCL 75S421
PSU BOARD: 40-L402H8-PWD1CG
it shows not even a flash of backlight when powering up.
but the tv appeas to turn on and i can hear the sound of the menus moving and clicking. i can power down the tv with the button.
testing the backlights with my tester all 4 strings lit up and showed similar voltage drops. around 110 or so.
unplug mb and leave only psu plugged into backlights (PSU + BL SELF TEST MODE?) does not light the backlights.
i do see 24v but 0v on PSON and BLON (i didnt write this down tho so cant be sure)
with mb connected, PSON... -
so i took out one of my spare gigabyte ep35-ds3r mobos from storage for use to do some cpu, ram and video card testing of stuff i bought from ebay and got for free from momaka. he bought 50 e8400 cpus for cheap from ebay some years ago and i decided to help him relieve him of some of his supply since he had waaaay too many!!
what did we say about hoarding too much stuff and depriving others of them?! *cough* socialism *cough* lol! 
i had to blow some dust off the board and heatsinks with the datavac as i didnt clean it up before putting it in storage. after finishing... -
I have a 60 inch Samsung UN60EH6000F flatscreen TV. The screen went black a few months ago Sound is good, backlight is good, no menu. I replaced the TCon board with a used board purchased from Ebay. It worked fine for a 3-4 months, then the screen started ‘fading' back. Once again, sound is good, backlight is good, no menu. However, this time the picture looks fine for about 10-15 minutes, then fades back. If I power cycle the TV, the display reappears, for another 10-15 minutes, then fades black again. Repeatable ever time.
I ordered a supposedly ‘new' Tcon board this time, and...
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