LG 55LM6410 No Picture, Has Sound

[bryn32]

Hi guys, hoping someone can help point me in the right direction.

I was recently at my sisters house and she owns the LG 55lm6410. It was on and working fine, then out of the blue, the screen went blank. The sound was still working fine though.

The backlights still come on, just no picture. When the tv turns on the screen lights up black/grey, then dims, then brightens, then dims and goes semi bright again.

The tv is only 2 years old and was $2000+ new. I would love to help her out and fix this one as cheaply as possible, and save her the hassle of buying a new tv.

The tv has 2 boards i the back, one which i assume is the power board and the other is the main board. Hopefully its one of those and not the display itself

Any help will be greatly appreciated

Thanks

[newtothis]

Re: LG 55LM6410 No Picture, Has Sound

Good clear pictures of the boards and overall layout please

[bryn32]

Re: LG 55LM6410 No Picture, Has Sound

Ill get some asap and put them up

[bryn32]

Re: LG 55LM6410 No Picture, Has Sound

Here are the pictures. If you need more just let me know

[newtothis]

Re: LG 55LM6410 No Picture, Has Sound

Ok there should be a board behind the plate of the stand - Tcon

Need to get access to it

*EDIT*

Scrap that, This has integrated TCON!

Ok remove the stand bracket and get pictures of the bottom boards

Also give us pictures of any voltage labels by any connectors so we can find the panel power outputs

[bryn32]

Re: LG 55LM6410 No Picture, Has Sound

Ok. Ill get some more pictures once ive finished work. I had the stand off and didnt see any boards underneath. The 2 cables that run from the main board to the display just go under the tv. Ill have another look tonight and take some pics

[newtothis]

Re: LG 55LM6410 No Picture, Has Sound

Right, This is going to be problematic!

I will warn you now that there is a good chance that this may not be repairable

[bryn32]

Re: LG 55LM6410 No Picture, Has Sound

I am starting to get that feeling too. But it would annoy me if it was just thrown out without being looked at and it being able to be repaired. Once i get the pictures hopefully we will know a bit more

[bryn32]

Re: LG 55LM6410 No Picture, Has Sound

Ok, here is a picture of the voltages at the main connector out of the power board to the main board.

I did a voltage reading on them and here are the readings, starting from top to bottom

On the left is what the label syas, on the right are the readings

P-DIM2 - 2.4v
12V - 12V
12V - 12V
12V - 12V
GRND
GRND
3.5V - 3.5V
3.5v - 3.5V
GRND
GRND
24V - 24V
PWR-ON - 3.5V (says it should be 24V)

Now all the readings seem normal, all but the PWR-ON reading. It has 3.5V from the moment you turn the set on.

Is this normal or is this the problem?

Thanks

PS, sorry the picture is on its side

[mmartell]

Re: LG 55LM6410 No Picture, Has Sound

The connector has a double row of pins but you've only measured the pins on one side. You might have to flip the board over to get access to the other row but as it is all voltages look good. This sounds like a tcon/mainboard issue. If there are any small smd fuses on that mainboard you should check them.

[bryn32]

Re: LG 55LM6410 No Picture, Has Sound

Yeah i see that now. There arent any obvious fuses i can see.

[bryn32]

Re: LG 55LM6410 No Picture, Has Sound

Ok. So the rest are ok. Error has no volts. P-dim has 1v. N.c has none. Drv on has 3.5. Vsync in has none. The rest are right

[mmartell]

Re: LG 55LM6410 No Picture, Has Sound

Yes. Did you remove the stand and the metal plate behind it ?

Any small fuses will be marked F1 or F2 etc

[bryn32]

Re: LG 55LM6410 No Picture, Has Sound

I have removed that plate and there is nothing underneath it. And i couldnt see any. Well not any that jumped out at me

[mmartell]

Re: LG 55LM6410 No Picture, Has Sound

Can you snap a pic of the bottom center of the tv where the plate was to show the ribbons ?

[bryn32]

Re: LG 55LM6410 No Picture, Has Sound

Itll have to wait till tomorrow. Ive gone out and away from the tv. The ribbons just look to go into the led panel. But i spose without showing you it may be different.

[mmartell]

Re: LG 55LM6410 No Picture, Has Sound

There should still be driver boards at least - this setup is baffling. Without any more information I would say at this point you need another main board if the tcon is integrated into it.

[bryn32]

Re: LG 55LM6410 No Picture, Has Sound

Going by what newtothis said the tcon is integrated in the main board. Ive found a main board on ebay for 100 plus postage so im tempted to do that. However im not sure if it will fit the tv. The eax number is the same between the two but the one on ebay is from a different model tv. Would it still work do you think? Ill get another picture of the bottom of the tv before i do buy it though

[mmartell]

Re: LG 55LM6410 No Picture, Has Sound

What tv is it from ?

Try heating your main board with a hair dryer for about 30 seconds and see if the picture comes back. Still an outside chance you have a weak solder joint somewhere.

[bryn32]

Re: LG 55LM6410 No Picture, Has Sound

55lm6700. The eax number is the same and all the connections look the same. When i get home tomorrow night ill try the hair dryer thing.