Interesting hack repair on a CTC-5, your thoughts?

[Steve K]

Doug:

That modification is how the contrast control in the CTC-7 chassis is wired.

Steve

[drh4683]

I just looked at the CTC-7 schematics and noticed the same thing and came to report back. Must have been a field modification to enhance contrast on the 5. I just looked on PW-400 and C410 is missing, a 22pf from pin 7 to 1 on the 12BY7. This cap should have been there per the original schmatic. There isn't even a place for that capacitor on the board in my set. This cap is not used on the CTC-7, so can I assume this wiring job was a modification at the factory?