Portacolor early model repair

[stragulus]

So, I got this what looks like the earliest '66 model Portacolor. Now I'm not familiar at all with repairing anything with vacuum tubes in it, and otherwise am an amateur electronics repair hobbyist.

When I received it, I brushed up on repair faqs, early color tv circuits etc. I took out the horizontal tube and vertical deflection tube and brought the set up on a variac (and isolation transformer, I know *that* much!). I measured B+ and at full 120V AC voltage it went up to 360V. The schematic calls for 270V but I foolishly assumed it is probably due to not being loaded down much.

So, I put the tubes back in and fired up the set. After a little while I heard what sounds like HV arcing slightly. After a few seconds more I heard a few popping sounds and switched the set off. I had taken a video of the set in a darkened room luckily and could see that the popping sounds were from what looks like arcing in the neck (area) of the tube. Can't tell for sure but can't really see what else would arc there. It also came with a 'pinging' noise that very much sounded like what it would sound like if you'd flick the crt with your nails. Anyway, I hope I didn't destroy the set just yet. Nothing else seemed out of the ordinary and it wasn't on long.

So analyzing the issue I now figure that the B+ voltage probably *was* way too high. Looking at the schematics (I have the sam's) the circuit looks like a voltage doubler circuit using 2 diodes and 2 electrolytic capacitors. If one of these diodes were shot, I suppose that could explain your 360V. If that were true, I suppose I should also worry about the caps in the doubler? Although I did take temperature measurements while it was on the variac and the big cap with the multiple terminals remained cool.

Anything else I should think of checking? Going to check on the diodes to see if that theory holds up.