Chuck,
I must be misunderstanding something? In your first post you wrote that all voltages produced by the LV transformer gradually drop after some minutes.
The 503 HV transformer is quite different than that of several others in the 500 series. T620 here is loaded by (almost) all other consumers and not just by the HV circuit itself. Moreover feedback is from -100 V, not from the HV voltage. I didn't think of this earlier, perhaps the term HV transformer is a bit strange. I now wonder what would happen when the CRT heater winding shorts to ground. Probably diode V692 would not survive this.
Albert
