Only 3/4 of the LCD turn on... if I unplug one of the "LCD" strip

Question

TCL Television

Televisions made by the Chinese multinational electronics company, TCL.

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Sebastien Plante @excesset

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게시일: 2023년 6월 6일

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Only 3/4 of the LCD turn on... if I unplug one of the "LCD" strip

Hello,

My TV (TCL 65S434-CA) turn on and has backlight, but didn't have any images. After opening it, I discover that if I disconnect one of the output from the main board, it was displaying half of the image.

So I repluged the cable and disconnected the joint between the first and last strip (not sure of the name, but they are connected directly to the LCD, I think they are t-con?)... now I got 3/4 of the LCD working.

Now I'm wondering if it's the strip or the mainboard. What can I do to find if it's the case? I've tried to reverse both end, but it dosent work as I think the connector are reversed. So green with green and red with red work (whatever the cable I'm using), but green to red or red to green dosent work.

@oldturkey03 Did a quick search and could not find anything search for "tv tape off" or whatever, Google give me way to remove tape residue or tape car before painting and stuff like this... but I guess it's taping the pin to find what pin is cause the problem? I will try that tonight. Already did that before, just didn't think about it this time! Thanks for the suggestion!

I did take some pictures near the connector (quick before going to work), but I was not sure what I was supposed to take : https://photos.app.goo.gl/gKiUUdLBaajkKb...

I will probe the first few pin labeled as CDX near FPC 0129 on the main board to see which one are going to the secondary left driver board and tape those, then remove tape until I find the one causing the problem, hoping this fix will be "good enough".

Thanks a lot for your help!

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oldturkey03 @oldturkey03

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@excesset do not flip the cables. That potentially shortens out the boards. Those are not the T-con board but those are the LCD driver boards. By the nature of how they are attached to the board, those are essentially considered part of the LCD. They are not replaceable by a DIY’er and require specialized (and expensive) machinery.

From what you are describing, it sounds like a bad driver board but could be the main board (unlikely) For now, I suggest you try a „Tape Off“ (check Youtube for videos that explains it. There are now plenty of those) It is not complicated, but tedious. In the meantime, post some really good close up pictures of your mainboard and those driver boards. Lets see if we can find a way to check the voltages needed for your panel etc.

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@excesset something like this https://www.youtube.com/watch?v=pfrRhw7-... or this https://www.youtube.com/watch?v=YDm0Hhcf... is what I was referring too :-)

oldturkey03 의 2023년 6월 7일

manage to fix it using the tape method. In the end, only one pin was causing the image to not be displayed, now the overall the LCD look good, I can see a dead pixel on the bottom and but there's a "pulsing" line appearing everywhere. I'm unable to capture this on video or image, but fot example if I look at the YouTube logo, it will be red sharp and for maybe 300ms, it will have some more pale line in it (it will be stripped red / pale red) then come back full red. Can't really notice from far so it's okay and I guess it's related to the pin I taped (missing sync signal?).

Thanks a lot @oldturkey03

Sebastien Plante 의 2023년 6월 7일

@excesset It is possible that this is caused by that but I would suggest you go ahead and leave the one you have fixed but continue some more to see if you can improve this. BTW Great Job!

Repair is War on Entropy!

oldturkey03 의 2023년 6월 7일

@oldturkey03 Hey, the "weird line" that are moving through all the screen seem to be more present, so you say I should open it again and try to block some more pin and maybe I will stop this?

Thanks again !

Sebastien Plante 의 2023년 6월 22일

@excesset give it a try. Possibly that more of the driver board is getting further damaged. I'd try it.

oldturkey03 의 2023년 6월 22일

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@excesset something like this https://www.youtube.com/watch?v=pfrRhw7-... or this https://www.youtube.com/watch?v=YDm0Hhcf... is what I was referring too :-) — oldturkey03
manage to fix it using the tape method. In the end, only one pin was causing the image to not be displayed, now the overall the LCD look good, I can see a dead pixel on the bottom and but there's a "pulsing" line appearing everywhere. I'm unable to capture this on video or image, but fot example if I look at the YouTube logo, it will be red sharp and for maybe 300ms, it will have some more pale line in it (it will be stripped red / pale red) then come back full red. Can't really notice from far so it's okay and I guess it's related to the pin I taped (missing sync signal?).

Thanks a lot @oldturkey03 — Sebastien Plante
@excesset It is possible that this is caused by that but I would suggest you go ahead and leave the one you have fixed but continue some more to see if you can improve this. BTW Great Job!

Repair is War on Entropy! — oldturkey03
@oldturkey03 Hey, the "weird line" that are moving through all the screen seem to be more present, so you say I should open it again and try to block some more pin and maybe I will stop this?

Thanks again ! — Sebastien Plante
@excesset give it a try. Possibly that more of the driver board is getting further damaged. I'd try it. — oldturkey03

TCL Television

Only 3/4 of the LCD turn on... if I unplug one of the "LCD" strip

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