Well, 'tis a puzzlement to me. The only thing I see near the switch (which opens B+ to the bandpass amp) is a 6800 ohm and 0.1 uF bypass. It's a wild guess, but you might check those. Also make sure the grounds on the chroma board are solid.

Everything else in the chroma section is running with chroma on or off, so it's hard to see how it could be there.

Hmm. I will investigate further...

I was wrong...

Resistor and capacitor check fine and the grounds are all solid. I am at a loss.

Trying to figure out what could couple something at that frequency to the CRT.

Some straws to grasp at:
Does it change when you adjust the color killer control?
Maybe check the caps (especially .01 or larger) and other stuff in the color killer section?

Killer control has no effect. All caps on the chroma board have been replaced so I dont think it is that..

Well, I'm stumped. I don't mean to be insulting, but have you double checked the values of the bypass capacitors? Other than that, it's time to put a scope on the CRT leads, and if you can see it, trace it back to the source.

I will try that. Oh and the values are all correct. I may just try and deal with it as it won't be used all that much. I wonder if it is a problem with the fact that I am injecting a composite video source? This never showed up until I modified the set to accept composite inputs.

Of course, any modification is suspect, but how in the world would it come and go with the color switch?

I really have no idea. At first I thought it was shielding related on the coax cable, but I have since got a properly shielded and grounded cable so It cant be that. I think I might just cut my losses and live with it. :scratch2: