I noticed that there is no color distortion in the menu box on the top left hand side of the television. If the DMD chip or the color wheel was going out, it would go out on every part of the picture, and not just the broadcast, leaving the channel box intact. If you look, the box doesn't change at all, except for the transparent picture behind it. The fact that it turns off may simply point to a power supply, but without inspecting it, it would be hard to determine.
The mainboard, from what I understand, does include the DMD. Not that I think this is the problem, but because you asked.
I have a 3-year old Samsung DLP HLR5067WAX/XAA with various problems. First, it doesn't respond to pressing the Power button (on either the TV or remote). When I plug in the unit, the system automatically turns on and goes through its normal self-tests/lamp comes on/and color wheel is spinning (based on sound). Picture is highly distorted, scrambled and jittery, but audio seems normal. After about 15-20 seconds the picture freezes and audio goes out, then the picture goes out also. After another 5-10 seconds, the distored picture and audio come back. This cycle repeats. The TV will not respond to power button or other commands (eg, I pressed MENU on the remote, but no response). I unplug the unit to turn it off.
I believe I may need to replace the main board, but I want to be as sure as possible because the main board is expensive and I'm worried it won't fix the problem. The main board PCB is labeled: Hurricane2 L64C HLR4266W. Rev H2ANALOG V1.2 2005.04.12. Code BP4-00214C.
To get even the limited picture that I do get, I believe the lamp, ballast, and color wheel are working. I'm not sure if the DMD itself is working or if the chip also needs to be replaced (I think replacement boards don't automatically come with the DMD, right?). The unresponsiveness of my TV might suggest that something else beyond the imagining is having problems (unless the system behavior is "normally" erratic when there's a DMD failure).
I've also taken a video showing the failure symptoms which I described and uploaded it to YouTube:
Thanks in advance for any assistance!