Monitor the clock and data lines in the set while it is operating until it
acts up.
I would bet you have a problem that is causing the clock or data lines to
get squashed.
I have seen the tuner do this, the d/a converter on the convergence pcb, the
pip processor, the T-Chip, and other cause odd intermittent problems just
like what you describe.
You are simply going to have to hook up your multi channel digital storage
o'scope to key voltage areas and clock and data lines until you see the
change, then you can start trying to track it down by process of
elimination.

FYI over the last several years it has become virtually imperative to have a
multi channel DSO as many sets are now having very intermittent type of
problems, especially on the many clock and data line controlled ic's and
multi-processor sets. There is simply no other cost effective, time
effective, way to track down some of the problems we see in a modern tv set.

David

User wrote in message
...
I have seen queries to this problem but no solutions. Projection tv
loses convergence and OSD then when you depower it a loud thud comes
out of the speakers.. Sometimes unplugging and plugging the set
several times will bring it back but usually all you get is an
unconverged green and blue Parental Co display to the far right or the
screen or an illuminated raster but no video, if left off all night it
starts working again in the morning. All critical components have been
replace cr4118 cr402, c4401, c4402, cr4122, c4102, c4108, Q4101,
U4101, c4108, etc. etc. When working the picture is like a new set
with excellent pincushion control. Does someone out there have the
solution for this problem?