I've been blessed!

[old_tv_nut]

Originally Posted by bgadow

Had you swapped the HV regulator? (I can't remember, was it a 6BK4 that early?) Maybe a bit gassy? Stabs in the dark.

I'll try that tomorrow, but as you say it feels like a stab in the dark. I have already tried the horizontal oscillator and output, which seemed more likely because one end of the brightness control gets a negative voltage from the grid of the horizontal oscillator.

Unfortunately the horizontal circuit board is hidden behind the high voltage cage and practically impossible to get at, but I am going to measure voltages at the brightness pot tomorrow - slapping my forehead for not thinking of it before.