I have spent hours over a period of days trying to figure out why the Audio Amp in this set wasn't working, it was dead silent except for a very faint bit of static if you touched a screwdriver to the plate of the output tube.
I poured over the schematic, checking wiring, checking resistors, checking voltages, convinced I'd wired something wrong, I tried jumping the field coil in the speaker and using a PM speaker, I tried different sources and not a peep, voltages all looked good enough that it should be working but it
wasn't!.
I had subbed the 6J5 where the signal comes in but I didn't test the 6F6 output tubes because no way could they be dead enough for it to be completely silent.
They had a nice getter and looked fine, anyway it's a push pull amp so if one is bad it'll still work on the other, and no way could they both be dead enough to kill the whole thing, could they?
Both 6F6 output tubes were completely dead, heaters lit, no shorts, no apparent gas, just absolutely no emissions at all. I couldn't find any 6F6 tubes handy so I stuck the first somewhat similar audio tube I could find in the amp, a 6L6 and viola, it worked fine on one tube. I dug up a couple 6V6's and plugged them in and the Amp is alive, of course now the TV chassis is somewhat dead waiting on a contrast control but one thing at a time.