LG 37lc55 turns on few minutes later screen goes out

[Blueeyes]

So it powers up works fine for 10 mins then the screen goes either lines or static or just goes black, unplugging and plugging it back in seems to cure the problem ive take then tv apart and changed out the capacitors on the psu board but still same problem any ideas? Back light remains on even when screens black and sound hasnt suffered yet

[Hamie]

Re: LG 37lc55 turns on few minutes later screen goes out

Check the fuse on the tcon.
You should get 12v on either end.
When the TV starts to fail does that voltage change?

[Blueeyes]

Re: LG 37lc55 turns on few minutes later screen goes out

No idea not tried I'll look at it when I get home can I use dmm to check that? If so how ?

[Nick's Tvs]

Re: LG 37lc55 turns on few minutes later screen goes out

To check your voltage on both sides of the fuse you need a voltmeter. Make sure to set it to DC voltage, so the straight line not the wiggly line. Place your black lead on ground, and the red lead on one side of the fuse then the other. You should take this reading after the tv goes dark.

[Blueeyes]

Re: LG 37lc55 turns on few minutes later screen goes out

If it is an over heating problem what's the fix replacing the board?

[Hamie]

Re: LG 37lc55 turns on few minutes later screen goes out

From his discription the TV isn't shutting down, the back light stays on. Just the picture goes. So I'd doubt the powersupply is at fault.

[Nick's Tvs]

Re: LG 37lc55 turns on few minutes later screen goes out

Edited out because I misread the original question

[Nick's Tvs]

Re: LG 37lc55 turns on few minutes later screen goes out

Hamie, you are correct, sorry Blueeyes, for some reason I thought the entire tv shut down. That is my fault, I didn't read the information properly. Please ignore everything I just said up until now.
Then yes I would definitely do the voltage test on the fuse after the tv goes dark. That should be your first test.

[Blueeyes]

Re: LG 37lc55 turns on few minutes later screen goes out

Yeah screen stays on and backlight stays on just screen goes fuzzy or has lines or goes black but unplugging from mains then reattaching fixes the problem

[Blueeyes]

Re: LG 37lc55 turns on few minutes later screen goes out

Ok will do

[Blueeyes]

Re: LG 37lc55 turns on few minutes later screen goes out

Ok done that and when pictures on its 181 when it goes drops to 131 using ohmz setting on dmm sounds gone this time with it so do you think it's the fuse?

[Hamie]

Re: LG 37lc55 turns on few minutes later screen goes out

No check voltage in dc volts, black probe to chassis ground red probe to one end of the fuse, it should be 12v when the picture is on, does it drop when the picture is off?

[Blueeyes]

Re: LG 37lc55 turns on few minutes later screen goes out

It's coming on at 12.22 on dcv then drops to 12.17 but not noticed any other drops at all

[Blueeyes]

Re: LG 37lc55 turns on few minutes later screen goes out

Ok its 12.02 when it's just turned on then when I attach blueray player it goes to 12.22 and stays there till it goes off then drops to 12.19

[Blueeyes]

Re: LG 37lc55 turns on few minutes later screen goes out

Not sure if this info helps but if there's nothing plugged in ie HDMI or ariel the problem doesn't happen at all

[Blueeyes]

Re: LG 37lc55 turns on few minutes later screen goes out

So this is where I'm at turn on TV and fuse reads 12.05top pin 12.03 bottom pin and when picture goes top pin reads 12.08 but bottom pin goes all over the place from 1-12.38 after a few minutes it regulated back to normal 12v area but once HDMI plugs in another few minutes down the road the screen turns to static the sound goes and it rotates between black screen and static removing HDMI fixes this straight away so is it a fuse problem?

[Hamie]

Re: LG 37lc55 turns on few minutes later screen goes out

The problem was not going to be a fuse problem, it was into a test to see if the main board was providing the voltage to the tcon.

By the sounds of it you have a faulty mainboard.

[Blueeyes]

Re: LG 37lc55 turns on few minutes later screen goes out

The problem was not going to be a fuse problem, it was into a test to see if the main board was providing the voltage to the tcon.

By the sounds of it you have a faulty mainboard.

So how do we diagnose the problem on the main board or is it worth just buying a new main board?

[vinceroger69]

Re: LG 37lc55 turns on few minutes later screen goes out

yes if only happening on hdmi a mainboard change will probably sort it just make sure all the numbers of any stickers match up.
It maybe worth doing a trying a factory reset in service mode first though although im not sure on a lg how to do one but maybe a more experienced member will advise.

[Blueeyes]

Re: LG 37lc55 turns on few minutes later screen goes out

The screen goes off no matter what but once its been on awhile it only happens on HDMI I changed the tcon just in case and I'll take a photo of screen on from cold