1970s Zenith Console - Troubleshooting

[ThePlague]

Hello all,

Exciting update! Thanks to help from BeamT, the set has come back from the dead. I was working on the convergence and just couldn't get it right. Turns out you need to have a lateral blue magnet, of which my set was missing. BeamT sent one in the mail and it worked great!

This is the first time the set has really been up in running in years. I am currently chasing down a brightness issue with the set.

The problem: Intermittent pulses in brightness. Sometimes whole screen, sometimes brief sections of the screen get brighter. Overall brightness seems to be down. The Plex picture is at max brightness and it can barely pull apart grey from black. Along with this, there has also been some screen jerking in the horizontal direction, usually bottom portion of the screen. Some fluctuations will also occur and can be audible through the speaker. I've recorded a video of the issue, but will have to link it later.

Work Done: I replaced the Horizontal module (9-57) back to the original one in the set (had replaced with NOS). Initially, this brought the brightness back up and it held until power down of the set. Since power cycling, cannot get this to reoccur. I measured the 24V (24V read) and 125V B+ (123V-125V tuned to blank channel, 135-137V tuned to active channel). High Voltage reads dead on 26 kV. No arching or abnormal noises. Percussive maintenance did not reveal and lose or intermittent connections. All pots have been thoroughly cleaned with DeOxit and Faderlube.

Appreciate any ideas on this! Its so close to being finished (until something else thats 50 years old fails).