Today's Mystery Guest (RCA CTC-4)

[Electronic M]

Originally Posted by miniman82

I also had an AGC pot that was smoked, that sure didn't help.
To fix the sockets, you can sort of repin them with new contacts from another socket. You have to be careful and do them one at a time in situ, but when you're done the job is worth it not to have bum connections on the PC boards.

What type of sockets did you get the new pins from?

I'll have to test the AGC pot when I get back around to my CTC-4.

[Phil Nelson]

Vigorous socket re-cleaning changed nothing. Next stop, Tunerville.



Removal meant unsoldering ten connections, but they were all easily accessible. I will carefully clean the contacts with swabs and liquid DeOxit.

Phil Nelson

[wkand]

If the video amp is after the tuner, signal path wise, why would a weak picture(while injecting at the control grid of the video amp) mean that the tuner was bad? Not saying it isn't, I'm just not following the sequence of events I guess.

[Phil Nelson]

I was just walking backward, doing a very basic check to see what sections could pass a signal. Seeing a picture when I injected video at the video amp suggested that things downstream from there were working (at least marginally). Seeing a picture when I injected an IF signal at the IF amp suggested that things downstream from there were working. So, the no-signal problem was likely between the antenna terminal and the IF strip.

The solution was simple, after all, and it turned up when I serviced the tuner. The UHF-VHF switch in back of the tuner was funky and it had stuck in the UHF position. Here is the switch working normally:



I'm not impressed with that switch, or the quality of the tuner in general, but it's all clean and operational now, and I can get a picture through the antenna input.



And now for that Wizard of Oz photo you've been waiting for!



Yah, we're a long way from a good color picture, but the CRT transplant was successful, knock on wood, and I think there's hope for the old girl, after all. Now to read up on CTC-4 setup procedures . . . .

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html