68 Zenith 25" color console

[Adam]

This turned into one of the strangest TV repair problems I've seen:

So I sat down to watch TV and eat dinner and after a few minutes it lost HV entirely. That ss 3A3 just went out. So I put a tube 3A3 back in… and my black horizontal lines were back.

Then I remembered that a similar effect was caused by the HV rectifier filament winding arcing to the chassis on a CTC-10 I had. So I change that (which isn't nearly as easy to get to in this set as it was in the CTC10). But that didn't fix anything.

Next, even though I had looked at the cup and cleaned in there and it looked ok to me, I decided to try another. I had a used spare cup and socket I knew was good that I had pulled from a '68 Zenith 21" color metal cabinet set I had parted out about 10 years ago, and it was identical to the ones in this set. The problem was still there after I swapped in those, but it sounded like the arcing I was hearing that I was previously sure was in the HV cage before was coming from somewhere else...

If you look at the pic, you can see that spring going across the back of the CRT. It was that that was arcing (to itself and to the CRT), and I removed the spring and the problem went away, completely. But, if I cranked the brightness all the way up it would occasionally arc from one of the yoke-holding springs to the CRT, so I moved it to the other side of the yoke (where there was no label) and it seems ok now. It seems as if the problem was caused by that spring being over that label. Initially the label was insulating the spring from the CRT and it was like not having the spring there at all (and the problem went away). Then it burnt a few holes through the label (which you can see in the picture) and then the arcing started and the problem resumed.

But that doesn't explain what caused that solid state 3A3 to go bad so quickly. It also doesn't explain why it was doing it with the other CRT in there (but not nearly as badly) with no label in that place. Could that cup have been starting to break down but mostly ok, and that was contributing to the problem as well?

Also there was a small resistor (10 ohms 2W) in series with the 2nd anode, placed under the 3A3 socket on my set. But it was nowhere to be found in my schematics for the 20Y1C48 and there wasn't one connected to the other socket I swapped in either, so I just left it out. It doesn't seem to make any difference, but should I put one back in, or is it ok to just leave it out?