21-CT-55 power supply failure

[miniman82]

I suppose I should have my own by this point, but I've always taken the position that if in doubt replace it.

[miniman82]

Another day, another 12 caps replaced, still no change. There's definitely hum bars rolling vertically up through the picture when using an RF signal through the tuner, perfect picture when injecting composite into the video amp. I'm at a loss.

[Penthode]

Have you considered a possible heater to cathode short in a stage prior to your baseband video injection point? That is the Tuner through the Video IF. A heater cathode short could inject the hum and could create a higher current draw if a stage is dependent upon a cathode resistor bias arrangement. And a partial short is sometimes not obvious in a tester.

Terry