Today's Mystery Guest (RCA CTC-4)

[Phil Nelson]

I hate to cry Uncle, but I don't think I can take this set any farther without getting it aligned. I contacted the local collector club and asked if they know anyone in the Pacific Northwest who would try that if I delivered the chassis (or the entire TV), but got no response.

When I move the fine tuner, there is a very broad area in the middle of its travel where you bring in a fine B/W picture. You can only get color (true color, if it's a good day, or rolling bars, if it's not) at the opposing extremes of the tuner's range. This occurs on different channels, not only one.

On other sets, I have bypassed the tuner/IF and injected video and audio directly, but injection is not such a simple matter in a CTC-4, if I understood Pete's earlier remarks correctly. I guess I'll wheel this guy out of the shop and work on something else for a while.

Regards,

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

[Findm-Keepm]

Too bad Bob Andersen isn't closer.

http://videokarma.org/attachment.php...hmentid=168681

[Pete Deksnis]

Originally Posted by Phil Nelson

On other sets, I have bypassed the tuner/IF and injected video and audio directly, but injection is not such a simple matter in a CTC-4, if I understood Pete's earlier remarks correctly.

Phil, the original 1956 RCA construction article for composite video inputs also included two circuits for the CTC4. The second might be the more useful as the other requires a 75-ohm composite signal. The second can be driven by typical consumer equipment composite video outputs, the yellow RCA connectors. The link (notice there are more inductors and caps in this-made-for-the-CTC4 design to develop the requisite curves):

http://antiqueradio.org/art/BROADCAST_NEWS_0656_4.jpg

Pete

[Electronic M]

Originally Posted by Pete Deksnis

Phil, the original 1956 RCA construction article for composite video inputs also included two circuits for the CTC4. The second might be the more useful as the other requires a 75-ohm composite signal. The second can be driven by typical consumer equipment composite video outputs, the yellow RCA connectors. The link (notice there are more inductors and caps in this-made-for-the-CTC4 design to develop the requisite curves):

http://antiqueradio.org/art/BROADCAST_NEWS_0656_4.jpg

Pete

Now this is a tempting solution to my alignment troubles (which are at least as bad as Phil's)! I just found what I think is the correct tuning knob, and cleaned my bench enough to fit it so this may be god telling me to get back to my CTC-4...

[Phil Nelson]

Well, that seems worth a try. At least it would be easier to evaluate the chroma circuits if I knew I was working with a clean input.

Thanks for the tip!

Phil Nelson