RCA CTC-5 Deluxe Chandler Restoration

[etype2]

Originally Posted by old_tv_nut

Does the color control on your set have a switched OFF position at the CCW end? I believe my Super chassis does, though I haven't used the OFF position for years.
Now I wonder if it could possibly affect the tracking a bit (though not intentionally) in the OFF position - have to try it.

I don’t know for sure, but found this from bgadow. I can verify my set has a color killer circuit.

Re: Were there any Early Color Sets that could Switch to Bla
#21 • 08/19/2011 11:00 pm

I wonder if the color switch was only used on the Super model CTC-5? I have a Deluxe and I just checked it. I had never noticed any switch to that control and, indeed, there is none. Or it could have just been a production change. I'm thinking maybe they eliminated the color killer on the cheaper model?

I have a Motorola from about '68 with the neon indicator. I've heard of a Hoffman that lit up the color & tint controls when a colorcast was tuned in, but I've never seen confirmation of that.

[old_tv_nut]

I suspect the switch was only in the Super chassis, as maybe its color killer was not as reliable as the Deluxe. Hopefully, owners never used it, as it could lead to nuisance service calls if someone turned off the color and forgot it.

Edit: an annotated copy of the schematic (I believe it's from the ETF site) shows in red pencil modifications to the Super color killer circuit, so I guess there were problems.
I don't have a video source without a color burst, so I can't test my set, but I'd guess the trouble would have been opening up the color circuits on noisy fringe-area monochrome signals.

[reeferman]

Maybe this will help answer your question (S104). It was taken from the RCA Field Service Guide 1966 edition. The CTC-5N PCB has no mention.

[Penthode]

I suppose the question is what is the utility of the color killer these days?

The color killer was useful when broadcasters were obliged to remove the color burst on black and white broadcasts. With no one looking after our interest switching off the burst, the circuit has no longer any practical utility.

Or does it?

I have a video switcher before my RF modulator that switches the DVD player outputs between the composite color signal with burst and the Y or monochrome signal output which does not contain the burst. Besides removing the interleaved chroma in the luma thus improving the monochrome reproduction, it also drops the burst which provides the basis to test the effective operation of the color killer circuit.

[TVBeeGee]

Excellent approach to playing your monochrome DVDs, Penthode!

FYI... On professional broadcast color monitors in the 1960's and 70's, such as Conrac and many others, when color burst was absent the monitor not only killed color demodulation but also switched the Y video to wideband. If these monitors were properly converged, they were amazingly sharp for monochrome content without color burst.

I was so impressed when I first saw this that I modified my lowly home color TV to do the same thing! (Bypass the delay line and 3.58 filtering.) Even looking at an OTA signal at home, it was quite impressive to see the increased sharpness on monochrome content. Of course, this was in the days when burst was dropped on monochrome and before comb filtering became common.

RCA quadruplex video tape machines often seemed to have trouble dealing with loss of color burst. Many facilities that had RCA tape would complain bitterly if they got a tape to play or video to record that didn't have burst. Ampex machines seemed to handle this without issues. I always suspected that this issue and similar ones may have eventually contributed to the practice of burst never being turned off. However, at one time, it was not legal in the USA to broadcast monochrome with burst.

[etype2]

Happy New Year to all. RCA CTC-5 January 1, 2026

[old_tv_nut]

Nice! Happy Holidays!