On Jan 30, 7:21*am, "William Sommerwerck"
wrote:
I'm posting this to see if anyone /knows/ the answer, or has a reasonable
suspicion. I do not want to initiate an interminable chain of speculation..

I own a 36" flat-face 400-series Sony WEGA IDTV and, yes, I have the service
manual. The set has gotten heavy use over the past decade; I often leave it
on when I go to bed. It wasn't cheap, and I'd like to get at least another
five years out of it. For a non-HD CRT set, it has an excellent picture,
especially with RGB signals from a DVD player.

When the set's turned on, the HV is apparently shut off, so that the CRT
heater has time to come to full temperature, to avoid stripping the cathode.
(This is speculation.) Though sound comes on almost immediately, it takes
about 10 seconds for the raster to appear.

Recently I've noticed "something new". For about two seconds after the
raster comes on, the black level is too light. You can see the image
"darkening" as the black level drops to its "correct" point. This occurs
only when the set is "cold"; cycling the power doesn't cause this.

I'm hoping someone will say "I've seen this. It's the ___________."
Troubleshooting this set won't be easy (if only because it's close to the
wall on a near-immovable stand). I don't want to tear into it until I'm
reasonably certain I can fix it on the first try.

Thanks in advance.

--
"We already know the answers -- we just haven't asked the right
questions." -- Edwin Land

The industrial Sony's do a very similar thing as the CRT warms up. In
those you're waiting for the beam current feedback to get up to speed.
Since you have the service manual, is there anything in there about
setting G2 by monitoring a specific set of lines in the vertical
interval?

G²