RCA CTC-10 color (and other) issues

[old_tv_nut]

Originally Posted by jhiesey

On channel 3, both modulators behave the same (weak, smeary color). That means there's definitely an alignment issue in the tuner, right?

The modulator I have isn't a Blonder Tongue; it's a Standard SCM550HP, but it also has an IF loop. Part of the reason I got it was so I could hook the 45.75Mhz IF output directly up to the IF stage of the TV, but I haven't actually tried that yet. I'll do that tonight.

The audio IF oscillation is using a tuner signal. What I observed is that if I tune the IF transformer it goes smoothly from kind of working to oscillating wildly at a bit over 4.5Mhz.

Yes, must be the tuner, but only on the tuned RF amp stage(s) for the bad channel(s).

Don't know what to say about the oscillation. Maybe use the scope probe as a handy capacitor and poke around looking for a sensitive point that is supposed to be bypassed and quiet but isn't?