"William Sommerwerck" wrote in message
...
How does anyone go about "rationally"
analyzing such problems?

See the cracked solder spots.

But that's part of the issue. A close visual inspection can be useful, but
it consumes a lot of time and is not "rational" -- that is, it doesn't
connect symptoms with possible causes. It's more an act of desperation.
(That is not an implied criticism. I'm a great believer in the "try
anything" approach to servicing, and often have to fall back on it
myself.)



With a good eye, one can scan a whole board fairly quickly for cracked
soldering, and combined with poking and prodding a live set with an
insulated stick can help to narrow it down. Once you've seen a few of these,
it becomes a matter of Ok this is another one of these sets, better resolder
the tuner grounds and see where that gets me. Once I started repairing CRT
displays, I found that most of them started to look pretty much the same on
the inside, and the same half dozen or so problems crop up on 95% of the
defective units.