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Steve McVoy, PM sent.
Phil, I have no illusions that I can solve such a challenging problem, but its sure fun to investigate. Back in the 70's I used my old Knight Kit emissions tester, EICO low frequency O-scope, and EICO VTVM to fix all my neighbors B&W tvs and did manage to get the 21CT55 working. Everyone that saw it found the picture quality amazing compared to the 70's vintage picture quality. I never was able to get very good convergence at the edges of the screen. I think I recall that the HOT coupling capacitor was leaky, which may have caused the first flyback to give out? I did have to replace the 30KV HV cap, as it was shorted. The 21AXP22A had been replaced with the 21AXP22A. A 21AXP22/21AXP22A data sheet PDF says "The 21AXP22A features an internal neck coating having high resistance which eliminates the need for an external resistor between the anode power supply and the tube to proctect against damage by a momentary arc." But the CTC2B Ultor lead includes a resistor between the CRT and the HV section. Is it possible that the internal CRT resistor reduced the current draw and allowed the HV to exceed the 30KV cap rating? I did have problems with arcs from the exposed HV part. I now doubt the accuracy of my old VTVM and HV probe back then.
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