CTC-4 Director 21

[SwizzyMan]

Was going to check voltages so I reconnected both resistors. After pulling the noise inverter 6u8 since it was connected to the resistor (thinking this may be the mis-biased tube.) to check for smoke, I got none. I put it back in the socket and still no smoke. The 5k resistor is no longer smoking and burning up. It is still warm to the touch but not burning hot. I now need to replace the 3.58 crystal. Phil Nelson was kind enough to donate a crystal to the cause so Im waiting on that getting here.

[DaveWM]

shorted tubes can smoke resistors, and shorts can be intermittent.

[Hagstar]

I wasted a lot of time on my CTC-4 thinking Hickok tested meant something. Indeed failure to work as a chroma amp or intermittent shorts weren't always detected. Tubes are cheap enough, and those 6U8s and AZs are considered expendable under such heavy use. I just order NOS (usually Sylvania or GE) for all critical tubes for any color set so old and keep the old ones for emergency/if they work spares.

[SwizzyMan]

I'll look around for any shorted wires, but my next order of business is to figure out how to get rid of the interference when the chroma signal comes in. It makes the picture unwatchable. I also have a bit of artifacts on the black and white signal now. I may just shotgun replace all resistors on the video board for good measure, but the chroma signal interference might be a different story.

[SwizzyMan]

Got a new oscillator crystal courtesy of Phil Nelson (Thanks a bunch). I got it awhile ago in fact. I just haven't had time to get back to the set until this weekend. Hopefully replacing the bad crystal will clear up some problems. It's been almost a year working on this set and i've still got a ways to go.