View Full Version : CTC-11 Tuner and Sound


Phil Nelson
05-31-2009, 01:26 PM
After replacing electrolytics, my RCA CTC-11 has a terrific picture on rabbit ears. Two things remain before I learn how to do convergence, etc. This is my first color project, so bear with me :)

-- Dirty tuner. You need to rock the tuner a little on some channels to get color or best picture. Channel 3 is completely black/white. What's involved with cleaning the tuner? Tried peering through the little holes in its case and didn't learn anything. I'm tempted to spritz a little DeOxit inside and work the tuner through all the channels, but not if that would be a Bad Thing.

-- No sound. I shelved this project so long ago that I forgot whether it had sound when I got it, but I think it did. The three tubes on the audio board are good. A soldering iron touched to the 6AQ5 audio output grid produces a buzz. Voltages on those tubes look high. 271v on pin 6 of the 6AQ5 output tube, where the schematic says 150v. 224v on pins 5 and 6 of the 6EW6 sound IF tube, where 150v is expected.

While I'm at it, an even dumber question. To power up with the chassis on the workbench, can you just leave the CRT disconnected? I don't have the stuff to make extension cables, and the alignment directions suggest you can do this ("the HV lead should be securely taped and kept away from the chassis").

Thanks!

Phil Nelson

zenithfan1
05-31-2009, 06:10 PM
Hey Phil! Color is a lot of fun, but a PITA sometimes. The best thing to do with the tuner is take it out of the set if the cover can't be popped off and access made to the inside. The best way I found to clean the tuner on a color set is to spray the de oxit in very small amounts on the contacts trying not to spray anything else, or use a Q-tip or something. Don't forget to lube the contacts with fader lube or tuner cleaner w/ lube if your de oxit doesn't have a lube in it, there's several different kinds I have found. You might be able to use just some tv tuner cleaner/ lube if it's not real dirty. I only do the de oxit and then lube two step method on really bad ones or Space command sets where I don't want to have to get up and fiddle with it after using the remote. The reason to be so tidy in there is to prevent tuner drift, that spray can wreak havok on a tuner if sprayed all over. I did it once, it sucked bad. The sound sounds like the usual failed part somewhere and that could be a lot of things, maybe someone more familiar with the 11 will chime in. The HV lead can be taped inside of a glass cup or jar but I haven't done it myself. I just hook up a half dead tube I have laying around, crude but works. I hope this helps.

bgadow
05-31-2009, 09:49 PM
My -11 has a problem like this. The tuner needs to be jiggled on some channels, and the audio has become highly intermittent. This is definately a tuner problem, as if I jiggle the tuner enough the sound returns. Now...I recall that the last time I used this set I had a revalation and knew just what it needed to fix it...and now, darned if I can remember! A good cleaning will probably do it, along with a check of the wires. It has been a long time since I've had the chassis out of my set and I can't recall how easy it is to reach that bugger without pulling everything.