I'm thinking of buying this Admiral

[MadMan]

After reading the Rider's TV Manufacturers' cure for retrace suppression, I was kind of disappointed because the resistor numbers do not match the numbers on the Sams schematic. Frustrated, I had put the issue aside. Recently I decided to give it a go again, and through very careful reading and educated guesses, figured out where the connection points were.

(From Rider's TV Manufacturers' Trouble Cures - thanks to bandersen for the link!)
For 20X1, 20Y1, and 20Z1 chassis:
1. Insert a 270,000-ohm, 1/2-watt resistor in series with the wire connection from pin 2 (grid) of the picture tube to the junction of R317B and C320.
2. Replace R447 (3,900 ohms) with an 8,200-ohm, 1/2-watt resistor and readjust the height and vertical-linearity controls.
3. Connect a .05-uf capacitor from pin 2 (grid) of the picture tube to the junction of C408 and R447.

For the 1st, the resistor and capacitor numbers didn't even matter, as pin 2 of the crt only goes to one junction, so that was it. For the 2nd, the major giveaway was the 3.9k ohm resistor. There are only two in the entire set, and one is like in the tuner or somewhere completely unrelated. For the 3rd, it calls for the junction of C408 and the already-identified R447 and it's a resistor to ground, so it could only be the opposite side.

I'm pleased to say this retrace cure works like a charm. It's perfect, there are NO retrace lines, period. Whereas before it was installed, glaringly obvious retrace lines were onscreen about 90% of the time. I used a .047uf capacitor. I had a .056 ready to try, and even if I put them both in parallel it made no difference. So it's not very picky about that capacitance. Also the old 3.9k resistor tested at 4.5k... makes me wonder how many other resistors have drifted. >_>

I then finalized the DC restoration. I made a tidy little prototyping pcb. Sacrilege, I know. I think it's a much neater solution than perhaps sticking a lug strip somewhere. Plus the fact that it's obviously modern will be less likely to confuse anyone servicing this unit in the future. The schematic posted in the previous post is the current iteration - big thanks to Dobulee for that!

As stated before, it's not perfect dc restoration, but it is an improvement. And it does this thing where a dark scene will start dark and fade to brighter (in about 1 sec). But at least that takes the shock away from the transition. Besides, even without that, it does actually make an improvement in keeping dark levels. However slight an improvement, it was pretty bad without it, so I'll take it.

Next step is putting the chassis back in the case. I've already fixed a couple broken bosses in the case - for the screws that hold the back cover on. And retapped the screw holes on the chassis.

Oh yeah, how would I direct inject video into this? I tried putting raw video right into test point B (I think) which is right before the video amp. It came through but was very faded and gray. Maybe it needs a transistor to amplify the signal? The test point being right before the video amp makes me think that's what it's for.