Stewart Warner T-711 help

[Radiotronman]

I have a Stewart warner t-711 I’ve recapped and it had high voltage at first and then disappeared. It’s basically the same as a ge 801 set. I can’t find any obvious bad resistor or what’s causing it. The fly looked suspect and I installed a new stancor nos one, but nothing changed. The 6bg6 hv output tube looks purple (gassy?) no matter which one I swap in. What am I missing here?

[Eric H]

The problem likely lies with the Horizontal Oscillator, the purple glow in the tube could be from drawing excess current, which it will if the Oscillator isn't running.

[Radiotronman]

I thought so too and have been checking around the horizontal multivibrator and even put in a new 6SN7. Can’t find bad resistors or mistakes.

[Tom9589]

I'd drag the oscilloscope out and see what kind of signals you have in the horizontal oscillator and output circuits.

[Electronic M]

If you don't have a scope at least check grid drive on the output tube (if too positive your probably killing your tube and fly). Also, check the screen voltage while you're at it...If grid drive is fine and screen is low, and the resistors are fine the damper is bad or there is some kinda open in the flyback circuit preventing it from drawing plate current (so all the cathode current goes to the screen instead of the plate and loads the screen grid down). If the screen takes too much current it might also put out some gas from the heating.