21-CT-55 power supply failure

[Penthode]

Some more questions:

Your right: it is hard to see whether there are two distinct bars or one. But the bar seems to appear sharply.

1. Which +285V is being pulled down: the +285V IF or the other +285V supply feeding the vertical centering control?

2. Did you change the rectifiers to silicon?

3. Have you tried putting back the old electrolytics for a test?

4. What did you last do before the problem appeared? (Did you see the problem before changing the electrolytics?)

5. What basis do you think the ballast too hot? (Between the two resistors, the ballast is going to dissipate close to 50 watts which will make it pretty darn hot!)

I wonder if by either changing the electrolytic capacitors in the doubler and/or changing the rectifiers you may have inadvertently introduced rectifier switching transients which are effectively being coupled to the RF/IF stages? A simple test for this is to place 0.01ufd 600v ceramic capacitors across each of the rectifiers.

My long shot guess is that if the capacitor impedance has changed maybe you are seeing the rectifiers switch on the screen?