I've had this set for several years without any problems. Recently, after turning the set on, it operates normally for three or four minutes, but then the lamp turns off. The set remains on for a short time afterwards (you can still hear audio), but finally the set turns itself off with the three blinking light error.
I've replaced the lamp and the ballast, no change in symptoms. Both the DMD fan and lamp fan are working. I've tried using a room fan to blow directly into the back of the set with the back cover off, doesn't help. There doesn't seem to be anything else wrong. No strange noises. Before the lamp turns off, picture and audio are fine. The behavior is very consistent.
Any help you can provide in troubleshooting this problem would be greatly appreciated. Thanks in advance.