Samsung S6187W thunks at start up

[dwbchomo]

Greetings all. I have a Samsung DLP 61" Model HL-S6187W that is about 3 1/2 years old. It has worked great but developed a recent issue. A complete description follows. Any assistance would be greatly appreciated. Thanks!

When turned on, the TV makes a "thunking" sound....

1. The TV seems to otherwise work fine. As far as I can tell, there is no lessening of picture quality or sound;

2. If I turn the set around and look through the grills in the back, a bit to the left of (what I think is) the lamp area I can see a green light. When the TV is turned off, that green light stays on for a few minutes. If I turn the set off and then shortly thereafter turn the set back on (BEFORE that green light goes out), it does not make the thunking sound. If I wait a few minutes, the green light will go out. If I then turn on the set, the thunking sound happens every time);

3. If I turn the TV off, unplug it from the wall, plug it right back in and turn it on, it will make the sound (thus, the green light I can see through the back of the set seems to be relevant in some way to the sound. If it stays on, the sound will not occur when the TV is turned off and then back on. If I wait for the green light to go off or if I unplug the TV, which makes the green light go off and stay off until I turn the TV back on, the thunking sound will happen every time);

4. Although only slightly, the thunking sound may be a little less pronounced when the TV is warmed up;

5. The thunk happens only once – right when the set is turned on (with one exception....see below);

6. The set does not take any more time to come on than it ever has as far as I can tell;

7. It is very difficult to tell for sure as I have not opened up the back of the set, but the sound seems to be coming from the general lamp area...perhaps a little higher and to the left but again, very hard to tell—maybe right above the green light;

8. The TV has not displayed any other type of erratic or unusual behavior.

The exception to Point 5

Yesterday, I turned the TV on in the morning (it had not been on at all that day). The thunk sound happened and kept happening. The tempo was very even with the sound happening about once per second. On the screen was a blue box that said “No Signal,” or something like that...it was the same box that comes up if you turn on the TV and the Satellite box is not turned on...except the Satellite was turned on. I turned the Satellite off then back on to make sure it was working properly. All the while the TV continued to make the steady thunking noise. Also, the screen was flashing in sync with the sound (bright...dim...bright...dim...bright...dim).

What I found really curious was that the sound continued even after I turned the TV off. I let it carry on for about 45 seconds or so, then finally unplugged the TV at which time the sound stopped. I had not yet discovered the green light connection and I would guess that the thunking sound eventually would have quit once whatever it is that is turning the green light on and off eventually shut down (seems to take several minutes for that item turn off).

I let the TV sit unplugged for maybe a minute or so then plugged it back in and turned it on. It made the thunk once and then came on fine. That was the only time the repeated thunking and no picture has happened before or since. But, once the green light you can see through the back of the TV goes off, it thunks again (once) every time it is turned on (but then works ok after that).

Very curious as to what might be happening and if some kinf of failure may be imminent. Thanks!