Before doing the cabinet reinstallation I did final adjustments on the ion trap, centering magnets, horizontal drive, vertical linearity and height. I had a good, stable picture. But when I moved the CRT, the yoke and its retaining ring came loose. The rubber retaining was too age-hardened to grip the glass neck or the yoke.
I soaked the rubber ring in wintergreen oil overnight. I reinstalled the yoke, and the retainer was supple enough to keep it firmly in place. But with power on, I got zapped when I tried to reposition the yoke. I poked around a big and found that one (only one) of the centering rings was hot--voltage too high to read on my multimeter.
From looking at the yoke, I can't see how there can be any electrical connection to the centering magnets. I'd previously handled the magnets with no problem.
I took everything apart again, rechecked the resistances and found an open circuit as shown here.
I corrected that, put the yoke back on, but found the magnet-electrocution risk was the same.
How and why do I have like a thousand volts at one of the centering magnets?
The whole schematic is at this link. It's hard to read online, but quite legible if you download it at the original size.
https://flic.kr/p/24Z7cYP
Thanks for looking.
- Henry