75um7050pla have backlight no sound

[Jbg1983]

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.

[nomoresonys]

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

[Diah]

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 side

[Jbg1983]

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.

[EazyBone]

How can it be at fault if your problem is still there..

[Jbg1983]

I tested it and it let current through both ways on one of the diodes.

[nomoresonys]

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"

[Jbg1983]

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.

[nomoresonys]

Diah had a suggestion in post #3, did you try that?

[nomoresonys]

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.

[nomoresonys]

That thread is here: https://www.badcaps.net/forum/troubl...g-strike/page2

[Jbg1983]

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.

[EazyBone]

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.

[Diah]

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.

show us please the U ribbon cable you tried to disconnected..!

[Jbg1983]

[Jbg1983]

This

[Diah]

correct.. yours T-CON on the panel or at MB let see the whole things

[Jbg1983]

[Diah]

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 side

[Jbg1983]

Hi yes has 12v