Another RCA CT-100 discovery B8001599

[Penthode]

Thanks for the wealth of information. I was earlier pondering why the focus and HV supplies were drooping on video high average luma level scenes. I suppose it was driving the tube to hard. Everything settles down if you back off the contrast.

The set otherwise appears healthy apart from one odd anomaly: when powering up, after about 40 seconds the sounds comes up and you hear the characteristic HV crackle. The picture is initially low contrast. About after two minutes the contrast comes up. It is as if one tube in the video chain is extra slow warming. When testing the tubes, the emission was good and I have replaced many (most) of the tubes.

Any thoughts?