Willem van der Berg wrote in
news
Hi all,

I`ve got a Sony Trinitron Colour 4:3 PAL TV (KV-X2141D), purchased in
1993. It`s hooked up to cable TV. Lately I have been experiencing a
very odd problem, which I totally cannot explain. Perhaps someone here
can help me.

My display will all of a sudden `lose` the ability to show colour. The
image will only output black & white on every channel. The problem
begins after 30-60 minutes of use and therefore makes watching TV
almost impossible. Switching the TV off and back on again does not
help. If I wait an hour or so I get my colour back. But then my TV
only takes minutes to revert back into black & white. If I wait a day
before turning it on again the old pattern returns: black & white
after 30-60 minutes of use.

Although my television is hooked up through a video with the cable
signal, I have confirmed that the problem is definitely my TV. When I
use tv-out on my computer (with a direct connection to the television)
the same problem occurs. That rules out both my video-recorder and my
cable signal. Which couldn`t have been the problem in the first place,
as de signal downstairs comes through in colour.

Here`s a twist: teletext always shows in colour, even when the tv
signal has dropped into black & white mode. I`m not an expert, but to
me that means that the screen itself is still working. I`m guessing
something is heating up and failing, but I can`t understand why the
damage would not be permanent or instantly occur.

Can anyone shed some light on this? Based on the symptoms, which is
the most likely place to look for the solution? Is it the TV or some
cable or something?

Any help appreciated.

Regards,
Willem van der Berg

Common faults that cause this problem in this vintage of Sony european sets
are dry joints on and in the tuner/IF can, plus an intermittent trimmer
CT202 ?