Bad T-con or bad panel??

[Alternet]

I have a 50UH5500 lg tv with no picture. Previously I thought it was due to the backlights. But that was resolved ( https://www.badcaps.net/forum/showthread.php?t=85170 )


Now I have this tv with fully functioning backlights and when I turn it on I get some start up sound as well. I figured the logic board is working. I see the optical port lit up and as well I'm getting voltage to the t-con board. I also now hear a buzzing that sounds like its coming from the T-con board.

I moved down to the t-con board and verified that there was signal going in.

Next I disconnected the left ribbon cable going to the screen and applied power. No buzzing and I get picture on the right half of the screen. (right and left looking at the back of the tv).

Then I reconnected the left ribbon cable and disconnected the right ribbon cable. Turned the tv on again and I get garbage on the left half of the screen and nothing on the right half. (again no buzzing)


*Edit* the side that does not have a connection is white


Reconnect the right ribbon (both panel ribbons connected again). I turned on the tv and get no picture again and the buzzing is back.

At first I thought this was a display problem and a bad t-con board as both seem sides seem to be producing something. But why it not display anything when both sides of the panel are connected. Is there a short in the screen some how?

Anyone have any insight?

[Diah]

Re: Bad T-con or bad panel??

Next I disconnected the left ribbon cable going to the screen and applied power. No buzzing and I get picture on the right half of the screen. (right and left looking at the back of the tv).

Anyone have any insight?

at this point of disconnecting the ribbon cable this should show white screen on the second half beside half picture..
so its panel issue...

[Alternet]

Re: Bad T-con or bad panel??

at this point of disconnecting the ribbon cable this should show white screen on the second half beside half picture..
so its panel issue...

On the side that doesn't not have a connection the panel is white

[nomoresonys]

Re: Bad T-con or bad panel??

Check the little mlcc ceramic caps on the panel driver board/the board between the tcon and panel for low ohms, usually expect over 100 ohms if they are ok.

[Alternet]

Re: Bad T-con or bad panel??

Check the little mlcc ceramic caps on the panel driver board/the board between the tcon and panel for low ohms, usually expect over 100 ohms if they are ok.

I checked them for shorts (none found) but I did not ohm them. I'll check that tonight.

[Diah]

Re: Bad T-con or bad panel??

On the side that doesn't not have a connection the panel is white

this is good sign.. then you have the ribbon cable some pins broken r shorted together on the ribbon... take them out and inspect them carefully with good loop

[nomoresonys]

Re: Bad T-con or bad panel??

Did you get pictures of both sides of screen when you did the one ribbon test?

[Alternet]

Re: Bad T-con or bad panel??

Did you get pictures of both sides of screen when you did the one ribbon test?

When the left side was disconnected I got a correct picture on the right side and white screen on the left side. (the image was the lg no HDMI input screen but only half of it of course)

When the right side was disconnected I got garbage of the left half (kind of like the attached picture but only on the left side while the right side was white)

*Please note this picture is not my tv and just a rough example of what i saw but it was only on the half of the screen that was connected*

[Alternet]

Re: Bad T-con or bad panel??

this is good sign.. then you have the ribbon cable some pins broken r shorted together on the ribbon... take them out and inspect them carefully with good loop

I swapped ribbon cables and still got the same results. If there was a bad ribbon cable i would assume things would have swapped sides.

[Diah]

Re: Bad T-con or bad panel??

I swapped ribbon cables and still got the same results. If there was a bad ribbon cable i would assume things would have swapped sides.

i just saw the photo...
do you removed the panel before?? so you may damaged it ??
ribbon need under good loop to inspect the pins of it from both sides.. good loop and light. don't trust only your eyes or glasses

[Diah]

Re: Bad T-con or bad panel??

could you show us photo on one ribbon disconnected at once

[Diah]

Re: Bad T-con or bad panel??

When the right side was disconnected I got garbage of the left half (kind of like the attached picture but only on the left side while the right side was white

in this case panel okay... you have the issue at ribbon cable or T-CON.. also if you have 2 LVDS connected from MB to T-CON need to inspect them

[nomoresonys]

Re: Bad T-con or bad panel??

"Tape method" might work, example there, not in English but self explanatory, there's a ton on youtube, quite a few that involve cutting but I think this is easier and it's reversible, sometimes have to play with size and location of tape, needs to be done carefully ribbons can be delicate, it's done on the bad side with the faulty display of course: https://www.youtube.com/watch?v=Ug7FsUSQpfY

[nomoresonys]

Re: Bad T-con or bad panel??

in this case panel okay... you have the issue at ribbon cable or T-CON.. also if you have 2 LVDS connected from MB to T-CON need to inspect them

Another ASSUMPION is what that is.

[Diah]

Re: Bad T-con or bad panel??

Another ASSUMPION is what that is.

its not assumption.. its judgment regards to the drops info OP give over here..

[Alternet]

Re: Bad T-con or bad panel??

i just saw the photo...
do you removed the panel before?? so you may damaged it ??
ribbon need under good loop to inspect the pins of it from both sides.. good loop and light. don't trust only your eyes or glasses

I did remove the panel to fix the backlight issue. But I never saw an image even with the flashlight test before I took it apart.

I don't see any damage when inspecting the screen but i can't rule out that the screen may have bent to much or something along those lines.

could you show us photo on one ribbon disconnected at once

I can take a picture tonight if you would like

[nomoresonys]

Re: Bad T-con or bad panel??

That does NOT prove there isn't a panel fault.

[Alternet]

Re: Bad T-con or bad panel??

"Tape method" might work, example there, not in English but self explanatory, there's a ton on youtube, quite a few that involve cutting but I think this is easier and it's reversible, sometimes have to play with size and location of tape, needs to be done carefully ribbons can be delicate, it's done on the bad side with the faulty display of course: https://www.youtube.com/watch?v=Ug7FsUSQpfY

the tape method mentioned here is for a double image is it not? Would this work for no image at all? (as i'm getting no image at all when both ribbons are connected. and also getting a buzzing that sounds like its coming from the t-con board)

[neilc6]

Re: Bad T-con or bad panel??

Your other post indicated you saw the LG logo flash. You likely damaged the panel removing it.

[nomoresonys]

Re: Bad T-con or bad panel??

It can work for other than double, the way I read one of your posts above is there was a distorted image on one side while doing the one ribbon test.