AGC on Zenith 24NC31Z

[consoleguy67]

I have a 1967 Zenith color set with chassis 24NC31Z. Every once in a while, the contrast seems to flicker darker and lighter. I've adjusted the AGC control down. Are there some tubes in that particular circuit that I should check?

Thanks,
Frank

[DaveWM]

if the agc is super critical in adjustment I would check a 5uf cap somewhere in that circuit. if the AGC react normally to adjustment then check the electrolytic in the contrast circuit, part of the video out IIRC.

[zeno]

6BA11 is AGC tube. Best test is light tapping of tubes
while watching picture. If you find a sensitive spot
try cleaning socket first. Changes in contrast can be
anywhere from the tuner through the IF's, video amps & AGC
you really gotta see it to tell.
I have the manual out if you have any more questions.

73 Zeno

[consoleguy67]

Thanks. I'll check it out and let you know what I find.

Frank.