My CT-100 lost HV (from losing one B+ line).

[Electronic M]

Originally Posted by dtvmcdonald

I could try your idea with the CRT only unplugged (both ends),
except I'm afraid for the flyback.

There was a tube type (wish I could remember it's number...) that was essentially a 10BP4 gun and base firing into a metal anode that was sometimes used as an HV dummy load in early sets...The 6BK4 and the like were refinements on it IIRC...You could probably use one of those or a 6BK4 connected to the CRT base and HV circuits to sub for the load of the CRT.

[old_coot88]

I once had a somewhat analogous problem with a CTC-36. Someone had spilled a sticky liquid in through the back. It caused a bunch of B+ arcing that had burned deeply into a pc board before the breaker tripped. Cleaned out all the char that was visible, but it still popped the breaker. Several more cleanings and it still popped.

Finally I jumpered the breaker to make the hidden leakage paths visible. They incandesced spectacularly, so I got them all finally.

The rectifier diodes survived the brutalization, but were replaced anyway.

[N2IXK]

Originally Posted by Electronic M

There was a tube type (wish I could remember it's number...) that was essentially a 10BP4 gun and base firing into a metal anode that was sometimes used as an HV dummy load in early sets...\

Sounds like the 5890, which was used as a shunt regulator in theater projection sets. kind of a grandfather to the 6BD4 or 6BK4 types. The RCA production documents describe it as a 5TP4 gun firing into a 2X2A anode assembly. 12 pin "duodecal" base as used on most early CRTs. I have a couple of them in my tube collection. Seriously obscure devices. Handy for load testing the HV on older B/W sets, or for testing a CRT tester....