Hi Bruce,
Already been down that road. Unplugging ribbons from T con to screen makes no difference to the fault at all.
Looks like LG has had a heat problem and used double sided taped and glued a nasty great alloy heatsink to a BGA chip on the AV board. (see pic) Looks like a bad mod which they even taped to the back of the screen in case it fell off i guess. The heatsink is just a cut of alloy strip, not even a proper heatsink
I thought someone had made there own mod until I search for another board and they were all the same. I took the heatsink off and noticed the double sided tape was not makng much contact. To use that size heatsink on such a small BGA chip shows they were pushing the chip very hard.
Looking at the power supply voltages the PWR ON command is there at 3.5volts and the power supply comes to life when turning on from the remote. What i noticed the DRV ON which i guess is the command for the led supply to come on is there at around 3.5 volts and the set runs quite happy for about 3 - 5 minutes and displays a correct image. Then the DRV On voltage drops out to zero and the set turns to 3 blinking LED. All other supply seem to remain. 13.2 volts stays there nice and stable.
When the blinking is happening the chips on the t-con seem to still be still running as I can fell they are warmish to touch as well as the heatsinks on the main AV pcb are warm as well. I get no sound or picture during the fault. I have put a light to the screen but there is no activity. The only way the set comes back to life is to leave it for a few hours then you get another 5 minutes of run time. Heat, cold make no difference at all.
Mike
