My big screen's picture will be normal, then some lines will appear horizontal in random sequence for a second or so then picture goes off on all inputs. The picture will reappear for minutes, hours,???. The dvd input will light up blue. the picture may work for hours or days, but becoming worse at going on/off. I have a masters electrician license, but I am not a tv repairman. Can anyone help?
It might be cold solder. Smack the set, does it react? If it does, you can re-solder the whole board. Look for hair-line cracks where the components are soldered into the PCB.