"whit3rd" wrote in message
...
On Monday, March 28, 2011 4:15:45 AM UTC-7, Mike Tomlinson wrote:
In article
s.com, Sean Hamilton writes

Is it likely that bad solder joints would cause vertical foldover in a
mid-90s CRT television?

Yes, but it's more likely to be a bad cap.

Visual inspection is not enough. You need an ESR meter.

Maybe not; the ESR issues crop up mainly in high-performance
low voltage power supplies (like computers); the vertical
sweep circuit doesn't need a low-ESR capacitor. It will
take (and work well with) just about any capacitor with
adequate voltage rating and capacity.

The capacitor is inexpensive; just replace it with a new one,
don't bother with testing the old unit.

I think you are missing the point of what he was saying regarding ESR. This
parameter is a valid test of the 'goodness' of any electrolytic capacitor,
regardless of its ESR pedigree. Even 'normal' electrolytics have a
relatively low ESR when they are properly functional. As they fail, that
figure will increase, and that is readily spotted with an ESR meter. As to
the OP's actual problem, whilst bad joints in vertical output stages in CRT
televisions were common, this more often lead to initially intermittent, and
finally permanent frame collapse, than geometry problems like foldover,
which the OP said was the problem he had. My money would be 100% on it being
a bad cap, or possibly the feed resistor to the output IC having gone high.
This was also a relatively common problem on many chassis, and could cause a
severe foldover, usually at the bottom of the screen where the deflection
drive current needed to be at its highest.

Arfa