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I was forced to mow the lawn last weekend so I couldn't do much with the TV. More this weekend.
Thanks 7"estatdef for the photos. The 6SL7-swap idea is genius, and if I have to go there, I will.
I don't notice much sound-level change from adjusting A9, but it does alter picture quality as expected, so I imagine it's working. I can try some of the other mods suggested in the photos, but will stop short at finding new IF transformers. Probably unobtanium, and a redesign is a lot of work for fixing something that ought not be broken.
Wa2ise, The voltages at the sound IF tube plates are correct per the Sams voltage chart. I don't have the data in front of me, but if I recall correctly, the first stage's 6AU6 plate was at 75 Volts, the other was at 150. I didn't check voltages across the cathode resistors, but will this weekend. The resistors themselves check ok though. Resistance checks of the IF transformers say they're not open-ciruited anywhere. Shorted, perhaps. They're pretty much 0 ohms at DC. I assume they put up their struggle at IF frequencies.
I put a 'scope on the sound-takeoff point and see some slight signal there. The load of the 'scope drags the sound level down even farther (half again?), so maybe a small observation there is normal. The takeoff is just a single loop of thick soft wire from ground, once-around the first video IF transformer, then about ten loops of tuning slug, then to the grid of the first 6AU6 sound-IF amp. So at DC, it's grounded, but I guess at sound-IF frequencies a small signal is induced. How much I should see on the 'scope, I'm not sure. I should probably restore another split-sound-system set, working, for reference. I have an RCA on deck that's split-sound too. I hate having 2 sets on the bench at the same time though.
I'll shoot a few pics of 'scope readings. Maybe something will click.
Thanks for all the help.
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