LG 42LE4500 No display

[Johnboy78]

Just brought another repair project....its an LED LG 42" tv (model number above) when u switch on u can here the relay click but screen is completely blank..relay also clicks when switched off.

Any help would be appreciated?
is there anything i can check myself?

Can post up any pics if it would help.

Thanks in advance.

[tom66]

Re: LG 42LE4500 No display

Pictures would help indeed.

[Johnboy78]

Re: LG 42LE4500 No display

want a pic of each individual board or close ups of the PSU and main boards?

[tom66]

Re: LG 42LE4500 No display

Every board and one of the overall layout.

[Johnboy78]

Re: LG 42LE4500 No display

[Johnboy78]

Re: LG 42LE4500 No display

if you need any others let me know.

[tom66]

Re: LG 42LE4500 No display

Check all the voltages along the power connector going to the main board.

Attempt to select a source and see if you get sound.

[Johnboy78]

Re: LG 42LE4500 No display

Ok will try that and post results back.

[dave bro]

Re: LG 42LE4500 No display

Hi,

I have the same TV with similar problem. It will turn on and work perfect for some time, and then the screen will go black but still with perfect sound.

I have looked at the caps and they look ok? I am unsure what to check next as I don't want to do anything that might damage the TV.

Also is it possible that the rca (yellow/white/red) causes the problems, or even the optical cable? The setup was rca cable to the sat box, optical optical cable and hdmi cable to the surround sound.

[tom66]

Re: LG 42LE4500 No display

When the picture goes out can you see the screen glow slightly or does it not glow at all?

[dave bro]

Re: LG 42LE4500 No display

Pretty sure there is still a glow on it

[tom66]

Re: LG 42LE4500 No display

Well please check in a dark room and confirm to us, because the diagnosis between glowing screen and no glowing screen is completely and utterly different.

[dave bro]

Re: LG 42LE4500 No display

Just checked it and the screen is not glowing

[tom66]

Re: LG 42LE4500 No display

OK, there is a connection cable going between the power supply board and the main video board. Can you see a legend label next to this connector? If so take a photo of it, or list the labels.

[dave bro]

Re: LG 42LE4500 No display





I hope these are what you mean?

Also I noticed if I dimmed the picture when it was working it would go black screen straight away? Not sure if that gives any my help. Thanks for you help.

[tom66]

Re: LG 42LE4500 No display

You need to check the PWR ON and DRV ON signals. Multimeter red probe on appropriate pin, black probe on chassis, 20V DC range.

[dave bro]

Re: LG 42LE4500 No display

DRV ON is 3.23V and PWR ON is 3.34V.
Do they seem right? or am I not doing it right?

[dave bro]

Re: LG 42LE4500 No display

Are they right? They are the readings before screen goes black, when screen goes black;
DRV ON is 3.23V and PWR ON is 3.32V

[tom66]

Re: LG 42LE4500 No display

OK, it seems like the power board is bad.

[dave bro]

Re: LG 42LE4500 No display

ok, thanks

what shuld the voltages be?
And anywhere I can get a replacement you know? Or is I worth getting replacement. TV is 2 years old?