1962 Magnavox Stereo Theater with a busted Theater...

[electra225]

My model 2MV418 Stereo Theater is an amazing device. A beautiful hardwood cabinet. The incomparable 93 series amp chassis, lots of bass, nice bright treble. Having remote control necessitated using 12" speakers, but they give little to nothing to the 15" ones in the non-remote jobs. This ST has the largest TV chassis available in 1962, a 27". It has a beautiful black and white picture. When it works. Therein lies the rub. It seldom works for more than maybe a couple times, then it goes on the fritz, usually while turned off. It has been totally recapped, new tubes populated. It likes to lose its high voltage. One time it was a dirty brightness control. I cleaned all the controls with De-Oxit, but apparently it doesn't work on Magnavox TV sets. One time, the cathode follower tube wasn't making good contact. Wiggling tubes restored operation. I'm overlooking something. TV repair isn't my gig, my diagnostic skills are tentative at best, then I'm terrified of high voltage. A better schematic is the first step. Then I am going to disconnect the plate lead on the Horizontal out tube and do a bit of voltage measurement. I want to clean the controls, yet again, very thoroughly and maybe multiple times. Ditto tube sockets where the tubes carry high current or pulse voltages. I need to make sure the horizontal oscillator is working. Ideas?

Thinking out loud here. What about the possibility of "tin whiskers" on one or more of the controls? The brightness, horiz and vert hold controls, and the contrast control are mounted on the underside of the top rear of the cabinet. This set had copious amounts of cigarette scum on it when I restored it. How does one check for tin whiskers, what tests do I need to do? Then, how do I fix the condition? This set has something odd going on.