Good Morning:
If you really wanna see if your AGC is working, you could build a single transistor amplifier
4 resistors, total 47K on the outputs, 450K on the inputs, 18V supply, give you a
nice 5V P-P signal swing and feed a signal to it, and put it on your video in test point.
Without a scope you would have to go by what is on the screen. You got other tv's
so pick one put a signal on it and turn the AGC through it's range and watch the
screen......
Something like this:
https://www.electronics-tutorials.ws...ier/amp_2.html
You have to try and reach your required 5V P-P signal, so give it a try, you might
even have to use 2 transistors if you need to flip the signal, so keep that in mind....
I'm sure Yamamma can help out with it he seems to be able to find all kinds of goodies
online.
Once you get a proper signal your sync sep & AGC should work as expected....
With all the stuff & Time you spent up till now I think this may be a good step
to take..... Just keep in mind you will only see some voltages change, not
necessarily see a difference in picture etc. because AGC will not have an effect
on the picture because the signal is fed late in the system......
Poor signal would look washed out & poor H & V Lock. Overloaded pic would be very
high contrast, & noise on white lettering, possible H or V Lock on dark parts of the
picture resulting in a tearing look. I'm sure there are example pictures online....
.