I have a Samsung HLN467W DLP unit that is almost 3 years old. Last week I had a problem where after about 5 minutes, the picture color would become distorted/flicker then the unit would turn off. There is no LED indication once it turns off and the unit does not make the "turn off tune" noise. Once the unit does turn off, it will not turn back on again unless it is unplug for a couple minutes. I replaced the lamp, though I did not feel that was the cause, with no change in status. Due to the flickering image, I am leaning towards the ballast, but that would be a guess. The color wheel is not making the typical "whining" noise when the bearings are going, so I am assuming the the color wheel is OK. What is getting me is that there is no LED indication during the picture distortion/flickering, nor when the unit shuts off. When the unit does shut off, the cooling fan remains on constantly even though the unit had only been on for a few minutes. I tend to think that the lamp is not that hot in a few minutes that it would need to cool that long. After 40 minutes of the cooling fan running after the unit shut off, I realized that the fan was not going to shut off so I unplugged it.
I have a 3 yr old HLP5085W with a very similar problem. Mine does not shut off, but the colors go crazy. Looks like multi-colored horizontal lines grouped into vertical rectangles (if that makes any sense). The problem is erratic and is not consistent in duration or onset. Turning the TV off and unplugging it (for a variable amount of time) seems to fix it. That fix lasts anywhere between 12 hours and 2 minutes. And yes, I did change the light just in case. I have a post on this forum with a picture of my screen during the problem.
I called Samsung and they gave me the number of the local tech. Who came over and said he thinks it's the DMD board. The tech was not too sure of himself, and the cost (over 850) was not worth it. So I took the TV apart and found the DMD board, which is the DLP brain, and the last thing connected to the projector. Since my problem was intermittent, I was having a problem understanding how a computer board works some of the time.
My latest analysis is that the DVI cable that feeds the picture into the DMD board is pulling downward on the connection point on the DMD board, and over time and heat cycles has weakened that connection. I was able to reproduce the problem by simply placing my finger on that end of the DVI cable. Very little pressure is needed. I devised a harness that takes that pressure off the connection point by keeping an upward presseure on the DVI connector and I have been problem free for a week. I hope it does not come back, since the problem started, it's never taken this long to reappear.
Thanks for the suggestion, Fadi. I will definitely look into the DMD cable connections as a possibility. Since my unit turns off after a 30-40 sec after the color distortion starts, I am thinking it may be an actual failing part instead of a loose connection. But it will be worth a try before buying a DMD board. Thanks again for the input.