It your transformer.it has two wires most of the time .if you listen very closely and hear a couple of snaps,then shuts off ,thats what it is .I just replaced mine,cured the problem.
I have a samsung hdtv and it turn on and off
I turn on the set its come on turns red then go off
Try to replace the capacitor on the power supply might be bulge, if not check voltage/ solder joints on horizontal output transistor and flyback transformer might be bad.
I have a rca d52w20 rear projection tv it started going off by itself then I waited a few minutes then it would come back on.now it will not turn on at all it clicks 3 times green light goes on but will not turn on..
Dear, there is some technical fault in it , no one can guide you properly than the projection tv repairer, as for problem one should take it to the skilled master to get the solution. One more thing if you want to check by yourself again then check one thing, is the sleep timer is on or not?