Well, I've suffered a bit of a set back. I tried adjusting the horizontal "sine wave" coil per the RCA service manual. I attached my scope to test point "E" as instructed, but the waveform appears to be the horizontal drive output, and not the the other waveform. In any case, turning the slug in the sine wave coil did not affect the waveform or the picture. Here's a shot of the waveform that I got:
I don't know whether the RCA service manual misidentified the test point or if there's another problem. As time went on, I was having more and more trouble keeping horizontal lock. I also found that the horizontal hold control (which is actually the horizontal oscillator frequency control) had to be maxed out in one direction to achieve lock. I tried readjusting the sine wave coil, but it again seemed to have no effect.
Eventually, I was unable to get horizontal lock at all. I powered the set down for a while, and when I powered it up again, I got no raster and the HOT started to red plate. I knew that I still had a bunch of maroon drop caps left which I thought might be the problem, so I pulled the chassis and changed out about 10 more, including those on the video amp/AGC board. When I powered up again, nothing had improved, the HOT red plated and no raster. I'm assuming that I must have lost horizontal drive, or that the horizontal frequency is way out of whack. I tried subbing tubes, and when I put in a NOS 6AU4 damper (even the the old one tests good) the HOT no longer red plated, but I still had no HV or raster (I also tried subbing a NOS 6DQ5). I'm not sure what that means. I inspected the fly, and I don't believe that it's the problem. The only caps left on the horizontal board are two mica caps which I didn't have replacements for. I am still pretty much a novice at this stuff and I'm not sure what to do next. I'm afraid of screwing something up. Incidentally, I never let it red plate for more than a few seconds.
I'd like to be able to power up just the chassis on the bench, but I assume that that would not work without the deflection and convergence yokes attached. I may see if I can power up the chassis with everything connected but the chassis propped up behind the cabinet. That would allow me to finally measure the HOT cathode current. Anyone know if that's possible? I'm feeling a bit frustrated at the moment.
Thanks for any advice,
Clark