"info" wrote in message
oups.com...

It may be something to do with the CRT heater supply, which could indeed
be
due to bad electrolytic caps, or bad solder joints, especially on the CRT
connector.

Dave,
I know about the dangers (I have a diploma in EE).
When you say it may be a bad solder/track, this does not explain
why the problem got progressively worse. A bad solder/track usually
causes an intermittant problem?


Yes but a CRT heater has a lot of 'thermal inertia' and takes a good few
seconds to go from off to on, on to off. A bad connection can often become a
good one once parts warm up and expansion sets in. With ageing, thermal
expansion and contraction and some arcing, a worsening connection can be
fully expected.

However, I agree the most likely cause is thermally sensitive components,
especially electrolytic capacitors.

Dave