Check for "dry", bad joint on your power supply. Follow your power cord into the set and look for a solder joint which is cracked, loose or dirty. Desolder the joint clean with file and resolder. Unplug power cord and wait about 2 hours before you try taking the back off as there will be stored power in the TV set capacitors, this will KILL you, so wait and wait. Or discharge the caps if you can.
GO CANADA GO!, January 2009
