TV Samsung LE40A656A1FXXC variable color bars image

[yoritomo]

TV: Samsung LE40A656A1FXXC
T-Con : BN81-01694A
Motherboard: BN94-01741B
LCD Display: Samsung LTF400HC01

Hello all, I need your help again, then I joined 2 pictures as it is an image issue.
The image is sometime correct, sometime partially good, when it has a partial good image it is always on the top of the screen, sometime no image at all just only color bars as a gradient moving with the image contain like a curtain.

I check already every ribbons and powers, I hesitate to say it is either the diplay or T-Con problem, can you help me please ? if coming from the t-con, any idea which chip may cause such issue ? The t-con looks no more available.





Thanks by advance.

[yoritomo]

Re: TV Samsung LE40A656A1FXXC variable color bars image

Hello all

Unluckily this time I don't have a salvaged T-Con to clarify this fault, as I could with many other ones. I have the oscilloscope but I don't really find any interesting signal to check on the panel side ... That is annoying i feel like having both hands in pockets on this kind of fault. On t-con board, I know already how to troubleshoot the power chip and gamma chip, but that is all, i miss knowledge about other parts and operations on it.

Good night all

[petehall347]

Re: TV Samsung LE40A656A1FXXC variable color bars image

maybe poor soldering . try heat from hair dryer .
also try twisting the frame a bit .

[nomoresonys]

Re: TV Samsung LE40A656A1FXXC variable color bars image

Maybe try the "cut tape" method, might not work but only cost the price of a piece of tape, sometimes have to play with position of tape, usually works when a gate driver is the issue, your fault doesn't look like the typical bad gate driver but who knows: https://www.youtube.com/watch?v=j7vl7-vZEL8

[nomoresonys]

Re: TV Samsung LE40A656A1FXXC variable color bars image

Could also try cleaning and re-seating ribbon cables from tcon to panel, some use a pencil eraser carefully don't want to damage them and lvds cable from tcon to mainboard and make sure they fit securely.

[yoritomo]

Re: TV Samsung LE40A656A1FXXC variable color bars image

Hello all, thanks for your replies.

petehall347

maybe poor soldering . try heat from hair dryer .
also try twisting the frame a bit .

I did already, no change, moving the frame of display ribbons did not show any change.

Could also try cleaning and re-seating ribbon cables from tcon to panel, some use a pencil eraser carefully don't want to damage them and lvds cable from tcon to mainboard and make sure they fit securely.

Yes that is the first think i did, and i used a tuner contact cleaner too in complement, vibrations on t-con board did not gives any results neither.

[yoritomo]

Re: TV Samsung LE40A656A1FXXC variable color bars image

Hello all

Maybe try the "cut tape" method, might not work but only cost the price of a piece of tape, sometimes have to play with position of tape, usually works when a gate driver is the issue, your fault doesn't look like the typical bad gate driver but who knows: https://www.youtube.com/watch?v=j7vl7-vZEL8

This did not work, i still don't understand how to mask tracks may provide a correct image ... he does not explain on the video which tracks to masks or how many of them, anyway the concerned problem is not the same at all, thanks anyway for the hint.

[budm]

Re: TV Samsung LE40A656A1FXXC variable color bars image

Does heating of the main board have any affect?

[nomoresonys]

Re: TV Samsung LE40A656A1FXXC variable color bars image

Hello all



This did not work, i still don't understand how to mask tracks may provide a correct image ... he does not explain on the video which tracks to masks or how many of them, anyway the concerned problem is not the same at all, thanks anyway for the hint.

Nothing is absolute and just like a bad tcon can present in different ways so can other problems, it's troubleshooting and it's not always easy.

[yoritomo]

Re: TV Samsung LE40A656A1FXXC variable color bars image

Hello all

Does heating of the main board have any affect?

Heating T-con and motherboard did not change anything as well as twist and vibrations.

It is right nomoresonys, sometime our job is doubled by some magic

Thanks again for your help

Have a nice day

[yoritomo]

Re: TV Samsung LE40A656A1FXXC variable color bars image

Hello again

I have some new clues

When the image looks normal, it has an issue anyway above clear writing on the screen, difficult to see on the picture, then i will describe it, i have on this image writings on bottom left of the image, it has kind of blue red and green fine vertical line, starting from there to the top of the screen, nothing below !



Other thing interesting , when the images is garbled and i place my finger on the t-con board, on the place marked by the red circle, the image is freezing, when releasing my finger, the image becomes normal. there is a power supply chip TPS65160A just beside. Perhaps i am doing a reset downing a power line there. I am not sure what to think about it.



Have a nice day