Disc Ceramic Caps failing, Doghouse HV...

[jeyurkon]

I'm worried about the disc ceramics in the set I'm recapping. One was missing it's coating and 20% of the disc broken off. You can see it in the first photo. Curiously, it had no leakage at rated voltage and not surprisingly it was 20% low in capacitance.

The second photo shows a disc ceramic in the HV Doghouse. The coating on it is peeling. It was open on the edge all the way around. The missing piece is from me poking at it. This one didn't have a wax coating. Don't worry, the bumble bee is going.

It's not clear to me whats happening. The rest of the disc caps in the set are wax coated and the wax is blistering. Some of them appear darker in areas.

I'm worried that I may have to replace them all. Since a large portion of the 143 capacitors in this set are disc ceramics, that would take some time.

Does anyone have experience with this type of behaviour?

One disc ceramic had been replaced with a paper cap. And a tubular ceramic cap replaced with a bumble bee. Guess thats all they had on hand.

There is a one turn winding on the HV RF transformer for the 1B3-GT HV rectifier. There is a 3.6 ohm 1/2 watt ceramic resistor in series with it. That resistor is open, which surprises me. I would have thought that with it running at a little over 1/8 watt a 1/2 watt ceramic wire wound resistor would last forever. The 1B3-GT tests good.

John