HLR5067WXXAA Unusual issue - can you help?

[abruni22]

I bought a HLR5067WX/XAA for $50 to see if I could repair it. The unit starts up normally, and you can watch TV fine. However, within a few minutes, the screen will suddenly turn black. The audio stays on. The lamp stays on(!) All fans stay on. No front panel lights illuminate. If you press Power at this point, the unit will chime and power down normally. If you press Source at this point, you do not see the names of the inputs cycle through (or anything at all - just black). I've reproduced the problem using several different inputs (S-Video 1&2, and PC.) If you power the unit off and back on, the picture comes back and the process will repeat. A couple of times the unit has stayed on for 45-60 minutes (i.e. until I turned it off), but usually it happens in the first 1-10 minutes. Any ideas? Thanks in advance!