At long last, it's actually working
Here's a
really poor quality clip. The battery in my good camera is dead and so am I - it's 4am
So what was the final problem? Well, I dusted off my B&K 1077 TV Analyst manual and put it to work. I already knew if I injected video at the grid of the video amp, I got a picture. So, I worked my way through the Rf and IF stages. That's one of the great things about the B&K - you can generate RF for most VHF channels and the right IF for older sets. Around 23MHZ in this case.
Here I'm poking around in a functioning set for a comparison.
Well, no picture at any of those stages, but I could see on the scope that my signal was making it up to the grid of the 3rd IF amp, but no further. That tube was good and I swore I had check the voltages already so I figured the problem must like inside the demodulator box (dotted line).
Interesting to see (at least to me). I've never opened that box before.
I couldn't find any problems though so I rechecked the 3rf IF amp again. Finally, I discovered a bad 220 ohm resistor to B++. It was open! I replaced it with a cruddy used resistor (can't believe I'm out of decent 220s), powered the set back up and was treated to snow on the screen for the first time.
Hooked up the B&K and got a decent picture. It might not look like much, but keep in mind that's coming from the antenna input.
Hooked up a video modulator and got a decent picture. Finally, I tuned in the last OTA station in Chicago on CH. 6. That's what you see in my video.
I'll tackle the hum in the audio tomorrow. Time for bed
