Chroma w/out Luminance in CTC-11?

[cbenham]

Originally Posted by Phil Nelson

I tested their voltages, which are generally in the ballpark except for pin 8 of 6AW8A, which shows 232 volts instead of 120.

This is purely a guess because I don't have a CTC11 schematic. If the plate voltage is high, look to see if the tube's cathode resistor is open or if something is driving the first grid way negative and cutting off the tube.

Best I can do in the dark. #;^) Cliff

[Phil Nelson]

Here's that part of the schematic (in two pieces, because my copy of the schematic is on two pages).

C2D is part of a four-section electrolytic can, so I'll have to get to it eventually. I already replaced C5 near the 6AW8A because it's on the PC board and easy to reach.

Phil

http://antiqueradio.org/art/temp/VidBoardSchem1.jpg

http://antiqueradio.org/art/temp/VidBoardSchem2.jpg

[old_tv_nut]

Check R49 (330k) - could be open (?)

[Phil Nelson]

R49 checks at 315K, but I'll replace it anyway, now that one leg's lifted out.

Phil

[Zenith26kc20]

Try following the video signal path with a scope. It sounds like a peaking coil may be open. I'll look at my schematic when I get home tonight.
Also, carefully look at the printed circuit around the video stages. They were sometimes notorious for crystallized connections on tube socket pins