Eliminating AC hum problems?

[peverett]

On the Setchell Carlson that I am working on, it seemed to be the veritical output. I could watch hum waveforms move past each other when the vertical was in sync. As they would reach the point where they added to each other the vertical sync would become very weak. The horizontal also had a hum bar, but did not loose sync.

Althought I had plenty of vertical height and good linearity, I substuted vertical oscillator and output tubes with no effect. I also verified that all vertical section voltages were within the spec given by the Sams photofact. All vertical section capacitors were replaced and the vertical section resistors checked and replaced as needed. None of this affected the hum.

One note is that a multi-section electrolytic capacitor in the power supply was replaced by individual ones. Has anyone seen this causing issues?