42LG30 TV flashing on and off, replaced power board, no change, stumped!

[theturboexpress]

I have a 42 inch LG tv (42LG30) that came to me with some issues. The previous owner reported that the tv sometimes turned itself on by itself and/or would randomly scroll through the menu options on it's own. In the few weeks that I had the tv, I never had this problem with it, worked great. We moved across country and when we unboxed the tv and plugged it in, it wouldn't turn on - the standby light on the front flashes red for several seconds, followed by a brief flash of blue and the screen popping on for a second or two, followed by more flashing red standby button and black screen. It repeats endlessly on a loop like this. I did alot of internet searching and read about the issues with bad caps for these tv's. I didn't see any obviously bad caps on the main board or power board, but thought maybe since the tv was having trouble fully powering on, it was a power supply/board thing. I ordered a replacement board, and installed it today, to no effect. Still does the same thing. I am completely stymied and would welcome any thoughts or ideas on what to do next! I took a video of the issue, the link is here: https://www.youtube.com/watch?v=J484MXRnqQ4

[cadiman]

Re: 42LG30 TV flashing on and off, replaced power board, no change, stumped!

I have repaired very few power supplies on these units.

Mainboard failure very common.

L/G panel ok

China panel not ok (au-optronics) ccfl and inverter fail common and go together.

If this is a 42lg30 with nothing after it that should have an L/G panel.

There were a few models of these 42lg30-ua, 42lg30-ud They are all the same but use different boards except for the power supply. It is very important you note this when looking for boards.

It would be nice to see the back of the tv. or have the whole model number so we know which 42lg30 you have.

[theturboexpress]

Re: 42LG30 TV flashing on and off, replaced power board, no change, stumped!

It is the ud version

[dejo87]

Re: 42LG30 TV flashing on and off, replaced power board, no change, stumped!

Did you ever get this problem figured out?
If not, try taking the power button/IR receiver board out, soaking it in alcohol for a few minutes (I used 91%), scrubbing it down with an alcohol-soaked toothbrush (pay extra attention to the leads for the IR sensor, mine had some residue around them on the back side of the board) , letting the board dry (a few minutes under a good ceiling fan on high should do the trick) and putting it back in the TV. Worked for me on the exact same set with the exact same problem. You can try unplugging the big connector on the right side of the power button/IR board right as the TV is powering up (screen still off) to diagnose this problem as well. If the TV stays on when this board is unplugged, this is probably your problem.

[dejo87]

Re: 42LG30 TV flashing on and off, replaced power board, no change, stumped!

Actually, the tiny power button on the board is what was bad. I took the tiny metal shield off of it with a small flat head screwdriver and took out the tiny plastic black disc button, so only the 3 small contacts remain inside. Then I took some thin double-sided mesh tape and stuck some aluminum foil to it, then cut it down into a very small square and stuck it on the outer power button's raised area that presses the inner power button on the board. There's not really any springiness when the power button is pressed now but the outer power button is stiff enough and has enough of a gap to reach the inner power button that it won't constantly make contact. Or solder on a new button switch from somewhere. Or just spend about $15 and get a new board. Or just deal with not having a power button on the TV and use a remote.