Dark, ghost-like, triangle-shaped area in upper right part of screen. Picture shows thru the area. What causes this?
I had the same problem on my 50" DLP. Today I took the light projection mechanism apart to get to the
mirror tunnel (a piece about 1.5" long located between the projection bulb
housing and lens housing) and, for now at least, the shadow problem has
been corrected on my TV.
It would be difficult to describe in detail without photos of how to
remove the mirror tunnel. Briefly, once the lower rear cover is removed, it
involves completely removing the entire assembly of the projection bulb and lens,
along with disconnecting 3 or 4 cable connections. This assembly is held in place with 3 large screws around the projection lens housing in the lower center of the TV. After it's completely removed from the TV, removing smaller screws will break down the component parts. Once you locate the color wheel (about 2" in dia.) between the bulb and lens, the mirror tunnel is directly adjacent to it.
Handle it all with care, and I strongly suggest that you immediately cover the protruding projection lens will a lens cleaner cloth (held by rubber band) so it doesn't get scratched or smudged while you're working on the assembly. This will all make more sense after you get into it. Just remember where everything
goes, both cables and screws!
My four mirrors had indeed shifted into a flatter parallelogram than it
should be. On my set the metal tunnel casing is molded so
that it doesn't allow for the mirrors to be in the shape of a rectangle;
it requires a parallelogram shape. The mis-shapened tunnel caused a small
portion of the metal mirror housing (on the lamp end) to protrude into the interior of the
tunnel, hence the shadow on the screen.
To re-shape the mirrors I gently inserted a nylon cable tie--with a
sharpened leading edge--into the tiny gap behind the mirror that had
shifted. In doing so the mirrors shifted back to the proper positions and stayed
there when I removed the cable tie. (Be very gentle with the mirrors and do not insert anything into the tunnel!)
It's not clear why this (now restored and larger) gap behind that one
mirror even exists, but to ensure the the mirrors don't shift again, I
inserted and left in a length of cable tie (which is near perfect in
thickness and width) in the gap. Time will tell whether heat will deform
Perhaps a similar-size strip of metal would be better but I didn't
have one. And I would not use any kind of glue or adhesive on these mirrors (as others have suggested); with their small size and the need to keep them crystal clear there is just too much potential to royally mess them up.
After putting it all back together and testing, the shadow is gone. Hope
this helps and works for others!
Nov 25, 2009 |
RCA HDLP50W151 50" Rear Projection HDTV