Well, this set is just full of surprises. I took the cover off of the tuner to double check all of the resistors and voltage measurements, but it's really tight in there and wasn't able to safely probe everything. Resistors were all good and voltages seemed a bit high and I wasn't really watching the picture and so put it back together and turned it back on.
Good news:
So... what happens next is that for no explainable reason, the picture has massive contrast, sound is loud and clear and has flawless sync all the way across both controls. What?? And... the AGC control now actually does something. It doesn't go all the way from no picture to white picture/no sound, but it does have a noticeable affect on brightness.
Odd news:
The voltages that were previously low or in question are now massively high. The 130V B+ supply is now measuring about 175V -- despite the fact that the two other B+ voltages right above it in the power supply are still right. The V7B plate that was supposed to be 60V and was previously measuring as 45V is now measuring 95V, and the plate and grid voltages on the IF tubes which are supposed to be 115-120 are now measuring 160V. The grid 3 on V11, that's supposed to be -10V, that was previously measuring -1V is now measuring -10.5V. Oh, and now adjusting all of the CRT voltages to the schematic is right about where the best, brightest picture is.
This is how it looks, though I was able to dial it in even better with the focus, fine tuning and width controls later. The video doesn't even do it justice -- this thing looks like a brand new modern TV in person.
https://youtu.be/dKXksyLwGqs
Note the sharpness and clarity of the text:
https://youtu.be/6pDbjJgIk1Q
Bad news:
Of course it doesn't like to be run with those voltages. After about 5-10 minutes, the picture starts to take hits like this. And yes, I turned it off as soon as I recorded this:
https://youtu.be/rYIgDQ-g3ZE
The only thing that was actually changed recently was that detector diode, and this was not happening right after I did. Previously the B+ supply voltages were all dead-on correct with the schematic and the IF's being fed from the 130V line were all correct while the sync circuits fed from the same 130V were all too low. I've never seen a situation where only one single part of the power supply divider goes from being right to being 30% high, unless a significant load was removed. If that were the case, and a tube that was drawing a lot of current got disconnected why in the heck would the set all of the sudden start playing WAY better?
Has anyone ever seen something like this before?
Very befuddled,
FK