Hello everyone, I finally managed to fix it. :D:D
The failure was a small 100pF capacitor connected to the cristal at 3.58.
Practically the oscillator was working at second harmonic and the color Falze the sides of the screen.
Now is great, thank you all for the advice I received in particular Phil for giving me the pattern. :thmbsp::thmbsp:
Here are the pictures of the result:

Wow great fix! Those are great sets, enjoy.

Wow!

I had one of those sets, but it used the 20y1c50 chassis. Even after all the work I did on it - it never had color bar reproduction that good. No fringe or drift at all.

Your set looks great!

Hello reeferman! I hate to reopen an ancient thread, but I too am looking for a schematic for a 16Z8C50 chassis. Some time ago, I found a specimen of that chassis sitting in a dumpster! I am revisiting this beautiful old set and am trying to fix it. I sent you a private message and an email to get into contact. Any help would be appreciated! Thanks!

If they don't get back to you by the end of the month message me. I should have the factory lit that I can photograph and post or copy and mail.

I'm working on this for VB. I have the sams and the factory schemo. Not the full Zenith service manual though.

What surprised me was the 1967 channel knobs :scratch2:, IIRC mostly seen on the 20X1C38 consoles. The three small knobs above give it away as a 1969 though:yes: