Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

[ermals]

Hi all!
I've recently run into an issue with my Samsung UN55H8000AF LED TV displaying no image. I've done quite a bit of research in terms of what could be wrong with it. Below are the steps I've taken prior to reaching out here for some assistance:

1. I've tried replacing the T-Con board (BN95-01594A), twice and have still experienced the same issue with all the boards I've tested with.
2. I've tried to remove one side of the ribbon cable that goes from the T-Con board to the panel and still not getting any image on left or right side.
3. I've checked voltages on T-Con and all seem to be correct.
4. I've made sure backlight works, and it does function correctly.
5. Sounds check works, and logic board seems to be working since it's able to receive input from my remote and from the hardware buttons on the TV.

Some things I have noticed:
1. Blue LED3 on the T-Con board is very faint and flashes three times before completely turning off and staying off.
2. The blue LED below LED3 on T-Con board blinks once then stays on.
3. Backlight works perfectly fine and visible on all sides of the TV throughout the strip.

What I have yet to do:
1. Replace logic board/main board.
2. Replace power supply.
3. Replace panel (would hate to go this far).

Attached is an image indicating the LED3 on the T-Con board. I'll also post some links below to a slow-motion and normal speed video of the behaivor of the LED's on the T-Con. You'll notice the LED3 in the slow motion video turns on very faintly, flashes 3 times and shuts off.

Slow motion video: https://www.youtube.com/shorts/E5YskaaT6kY
Normal speed: https://www.youtube.com/shorts/IWfSnlRzfjk

Any assistance would be greatly appreciated, I would hate to have to throw this TV out.

Thank you so much!

[nomoresonys]

Re: Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

"1. Blue LED3 on the T-Con board is very faint and flashes three times before completely turning off and staying off.
2. The blue LED below LED3 on T-Con board blinks once then stays on." So original and both replacement tcons do this exact same behavior with the tcon leds?

[ermals]

Re: Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

"1. Blue LED3 on the T-Con board is very faint and flashes three times before completely turning off and staying off.
2. The blue LED below LED3 on T-Con board blinks once then stays on." So original and both replacement tcons do this exact same behavior with the tcon leds?

That's correct! Originally I thought it was the T-Con board, so I replaced it and the same exact scenario was present on the newly replaced T-Con board.

[nomoresonys]

Re: Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

see if you have around 12 steady volts on each side of the tcon fuse, neg. probe on metal chassis ground pos. probe on each end.

[ermals]

Re: Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

see if you have around 12 steady volts on each side of the tcon fuse, neg. probe on metal chassis ground pos. probe on each end.

12.65 on each end of the fuse it seems. I've attached photos.

[dskall]

Re: Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

And with both ribbons to panel off you get same lights?

[ermals]

Re: Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

And with both ribbons to panel off you get same lights?

Yep, however with both ribbon cables disconnected LED3 doesn't faintly blink three times.

[dskall]

Re: Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

You have 3 leds on but dim. T-con change did nothing and your 12v is steady. Seems like bad ground.

[ermals]

Re: Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

You have 3 leds on but dim. T-con change did nothing and your 12v is steady. Seems like bad ground.

Yep, 3 dim flashes, then turns off on LED3. What exactly does a bad ground mean? Is it fixable or will it require new components?

[dskall]

Re: Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

I believe TV will work without t-con connected to chassis. And there are grounds going through LVDS cable, So maybe a problem on mainboard or cable.

[nomoresonys]

Re: Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

Yep, however with both ribbon cables disconnected LED3 doesn't faintly blink three times.

this means the third light stays lit or does not?

[triplefour]

Re: Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

check your panel boards. are there voltages there at the connector and any caps you can test?

[ermals]

Re: Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

this means the third light stays lit or does not?

It does not stay on. Only 3 very dim flashes then goes off completely.

[ermals]

Re: Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

check your panel boards. are there voltages there at the connector and any caps you can test?

I get 12v and 3.6v on the panel boards.

[nomoresonys]

Re: Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

I've seen the tape cutoff method work when third light was out, couldn't hurt to try, maybe block pins 2 thru 5 or 2 thru 6, might have to play around with which ones to block, maybe check those caps too, as suggested.

[nomoresonys]

Re: Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

not exactly sure but something might be detecting a problem and shutting down, maybe the cutoff will let it work, who knows?

[ermals]

Re: Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

I've seen the tape cutoff method work when third light was out, couldn't hurt to try, maybe block pins 2 thru 5 or 2 thru 6, might have to play around with which ones to block, maybe check those caps too, as suggested.

Just to clarify, am I blocking the pins from the main board to the T-Con or the T-Con to the two panel boards?

[nomoresonys]

Re: Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

tcon to panel.

[nomoresonys]

Re: Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

tape goes on one of the ribbon cables not both.

[ermals]

Re: Samsung UN55H8000AF - No Picture, Working Backlight, Replaced T-Con Board

tape goes on one of the ribbon cables not both.

Should I still try this even though I get the same issue when unplugging one of the ribbon cables? I was under the impression the tape method could be a solution only if I'm able to get a picture on one side with one of the ribbons to the panel disconnected.