With anything over about ten years you start by
replacing electrolytic
capacitors. If you want to test instead of shotgun then pick up an ESR
Why? I would agree that this problem sounds like a capacitor problem (I
would want to make sure the relateively low-frequency vertical sync
pulses were getting to the appropraite point, and I'd also want to be
sure thete was no mains ripple on the supply lines that could be
confusiogn the sync circuitry), but I realyl don't find the all 10 eyar
ole (or all 40 year old for that matter) electrolytics are defective.
meter, but it usually shows more than a few are
failing. If the monitor
is over twenty years old, then just replace all the electrolytics and
then troubleshoot - it there is still a problem that is.
No, torubleshoot first. It may be a capacitor, but you can't be sure
unless youtrace the signals and find out what is actually wrong.
Do take care to match the caps to the job they do - low ESR caps for the
horizontal, and caps that handle AC ripple for the linear power supplies.
The CM8833 (al lversions) has a swtich-mode PSU (on a separate PCB to the
rest of the monitor).
-tony