Hello, I have a Commodore 15KHz monitor that I tried to use as a TV set by attaching it to my decoder through a SCART lead. It worked perfectly for a while, then it started doing this:
Thank you very much for your advice. It's not doing that anymore. It looks like some oxide or dirt is present in the vertical size regulation knob, although I'm not 100% sure.
take it apart, clean out the dust in it for one thing.
That looks like HV leaking somewhere. You may also have some cracked insulation in the Anode lead or flyback coil. You could even have a cracked solder joint or moisture in it.
Jamie
That's another possibility.
Jamie
It's doing that thing again. DAMN!!!!
If the flicker problem changes when you turn the vertical hold or linearity controls that would indicate a pot problem.
Have you tried control cleaner such as MG's Tuner Lube? About the only way to restore potentiometers...
Otherwise it could possibly be HV leakage - take the rear cover off and turn it on in a dark room to see if there is any arcing. You would likely hear some sizzling noise too and smell ozone if there is a HV leak.
John :-#)#
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I know what happened.... You plugged tab A into slot D didn't you.
Slater, Those monitors, mostly made by NAP (Philips), were notorious for intermittents of all kinds caused by bad solder joints. When I get one of those beauties on the bench, the first thing I do is go over the main (and CRT) board and resolder all suspicious connections, then check for any other problems, if any. Pay particular attention to the flyback (LOPT) and H driver transformer, all power transistors, IC's and diodes, and all resistors of 1 watt and larger... essentially anything that generates heat. The movement of component leads via heating and cooling in normal operation eventually causes the solder joints to break loose. I'll bet your vertical sweep problem is caused by bad solder. Solder problems can show up when the monitor is cold but go away as it warms up... or vice-versa. Be careful when you pull that bottom metal plate off the PC board. It's soldered all the way around and unless desoldered carefully, you can damage the grounding traces. Good hunting!
Ray
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