Today's Mystery Guest (RCA CTC-4)

[Phil Nelson]

Originally Posted by wa2ise

Some vintage color TVs had a separate detector diode for the chroma, separate from the regular video detector.

Yes, that trace does look more like a luma-only stairstep pattern, but this set only has the one detector diode.

Originally Posted by miniman82

You put the signal right in to pin 2 or the 6CL6 and chassis ground, right?

Yup, signal to pin 2 (or 9) of the 6CL6 and ground to chassis. I re-cleaned the AGC pot and made some cursory measurements that seem to indicate it's OK. Let's hope it is not junk. It is mounted concentric with the 2.5-meg noise threshold pot, and I don't know where you would get a replacement dual 500K/2.5-meg pot nowadays. Worst case, you could drill a new hole and mount a new pot separately, but . . . .

I put the chassis up on the workbench and plugged in the yoke & convergence assembly so that I can do some more systematic voltage & resistance checks, and look at things more easily with a scope.

Phil Nelson