LG 50LN5750-UH horizontal lines

[Iceman_GER]

Hi,
I have this TV here from a friend and it's got some horizontal lines showing for about 2 seconds - picture is fine for about 3 seconds and so on.

no inputs are used - just power on and it does this constantly.

I got told it would be the t-con board, but that isn't the case.

I'm guessing it has something to do with the power supply board.

any help is appreciated,

cheers

[Alastair E]

Re: LG 50LN5750-UH horizontal lines

Looks like another bad panel to me I'm afraid....

One of the tabs--probably on the small chips at the side edges has probably failed.

[Iceman_GER]

Re: LG 50LN5750-UH horizontal lines

damn, not the answer i was hoping for.

Thx for your input.

[Shinju]

Re: LG 50LN5750-UH horizontal lines

Well, this is going from right to left, chances are it is screen failure though. Only way to tell is to enter the service menu but I think newer LG panels you have to have the Service Menu commander remote to enter the SM.

[Iceman_GER]

Re: LG 50LN5750-UH horizontal lines

I tried to get into the service menu by holding down the menu button on the TV and the remote simultaneously as explained in 1 of the stickies here, without any luck.

Also, I just checked the picture in the main menu. It's not those lines only.
-When the lines show up the lower part of the screen is shaking-

[Shinju]

Re: LG 50LN5750-UH horizontal lines

Have you taken it apart yet?

[Iceman_GER]

Re: LG 50LN5750-UH horizontal lines

kind of. back panel is off. changed the t-con bought at shopjimmy. inspected the power supply board for bad caps, and that's about it for now.

[Shinju]

Re: LG 50LN5750-UH horizontal lines

have you disconnected one side of the T-con going to the panel and see if the lines persist?

[Iceman_GER]

Re: LG 50LN5750-UH horizontal lines

1 half of the screen get's vertical lines when i disconnect a ribbon cable

[Shinju]

Re: LG 50LN5750-UH horizontal lines

reverse it and see.

[Shinju]

Re: LG 50LN5750-UH horizontal lines

Oh and photo would help too!

[Alastair E]

Re: LG 50LN5750-UH horizontal lines

Oh--and be careful pulling those ribbons and re-seating/swapping round--Only do when the set is switched OFF...

Its possible to stuff up either a T-Con and or the panel itself if done while powered up....

[Iceman_GER]

Re: LG 50LN5750-UH horizontal lines

1 side at a time diconnected

[Shinju]

Re: LG 50LN5750-UH horizontal lines

Connect both ribbons again, and take a photo with a source attached to the TV that displays a bright picture preferably a solid white/green/blue.

Horizontal lines is a rare fault on a LCD/LED (possible).

Only thing left to do is to break down the panel and check the TFT boards that connect directly to the Panel.

[tom66]

Re: LG 50LN5750-UH horizontal lines

Horizontal lines is usually gate driver failure, it happens. Now the modern panels integrate the gate driver on the panel ("Gate in Panel") they are more reliable (which is odd... usually technology seems to get less reliable as time goes on...!)

[Shinju]

Re: LG 50LN5750-UH horizontal lines

Horizontal lines is usually gate driver failure, it happens. Now the modern panels integrate the gate driver on the panel ("Gate in Panel") they are more reliable (which is odd... usually technology seems to get less reliable as time goes on...!)

Heh, I havent touched a LCD/LED in months! When did they start doing the GIP, are those the little flaps on the far left and right of the LCD glass itself?

I have been doing all Plasma for the most part :P Been a blast, and to think in the beginning I was the other way around!

As soon as I get the parts back from ModUSlink for the VT30 thats my last Plasma needing repair.

I have a UN46 LED thats doing some silly stuff once the VT is done I will get that sucker on the bench and out.

[tom66]

Re: LG 50LN5750-UH horizontal lines

Heh, I havent touched a LCD/LED in months! When did they start doing the GIP, are those the little flaps on the far left and right of the LCD glass itself?

Actually the opposite. That's the older type where the gate drivers are outside of the panel. Tear down a new panel now and you won't find them, as the little gate ICs are built into the display panel itself. This, theoretically makes it more reliable as there's no tab bonding to fail (though the gate bonds rarely failed, it was more the source ones, every little helps...)

I have been doing all Plasma for the most part :P Been a blast, and to think in the beginning I was the other way around!

Don't stop. You won't regret it. I fix a lot of LCDs but definitely prefer fixing plasmas. Not only does the end result look better in most cases but plasmas seem easier to fix, once you know what to look for and test. Bad LCD panels have made me very wary of picking up new LED-backlit LCD TVs...

[Iceman_GER]

Re: LG 50LN5750-UH horizontal lines

here are 2 pix with DVD for input. 1 pix with the lines, the other without

[Shinju]

Re: LG 50LN5750-UH horizontal lines

So the lines to away after it warms up?

Yeah it's probably a bad panel, I would just run it till it dies.

[Iceman_GER]

Re: LG 50LN5750-UH horizontal lines

little video

no, it is not constant - 2 seconds the picture is fine - next 2 seconds it's got lines and the bottom half of the screen is flickering/shaking

I have the feeling something is not getting full power.