Chroma w/out Luminance in CTC-11?

[Phil Nelson]

I was about to ask for advice on this when the forum moved, and I guess the old thread is gone.

Long story short, I have started working on my $1 RCA CTC-11 "roundie." The set was dead until I replaced a fried thermistor. I also patched up the horizontal hold control, whose shaft was broken off and which was bent and popped loose inside. I cleaned the usual things with DeOxit. The tuner is still awful; I can only tune in a station between channels.

Now it has great audio and the vert/horiz holds are fine. The picture is awfully dim. First photo is this set. Second one is my restored CTC-11 for comparison.

The problem is not in the CRT or convergence assembly. I hooked up this chassis to those parts from my restored CTC-11, and got the same bad picture. My CRT tester also shows emission on all three guns.

The color controls have an effect, but brightness and contrast do not. It was suggested by oldcoot88 that I have chroma, but virtually no luminance.

Looking at the video amp/output board, I subbed known-good tubes for the 12BY7A (video out) and 6AW8A (video amp & color killer). No change there. I tested their voltages, which are generally in the ballpark except for pin 8 of 6AW8A, which shows 232 volts instead of 120.

I will continue checking things, but I thought I'd throw this out in case I'm missing something obvious.

Phil Nelson