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#11
01-18-2022, 05:43 PM
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Another update, and I believe I've solved the mystery. My hunch was correct about V4A, the cathode follower. Waveforms confirmed that that tube section was not conducting sufficiently. Swapping it with V10, appears to have resolved the trouble. This tube tested ok on 2 testers, by the way!
In position at V10, the same problem tube isn't problematic here, apparently because of how it functions differently with the color killer. Replacing the stock Vid Amp transistor, Q1 with a modern 2N222 and and vid detector with a fresh 1N60 also livened things up a bit. This is the first set that I've operated on that has a cathode follower. My understanding is that this section provides impedance matching for the delay line (?) The only truly defective part was the broken degauss thermistor, which I replaced with a NOS one. 
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