CTC-4 Director 21

[old_tv_nut]

You say "superior black and white picture", but I don't see the correct luma in the color bars. Do you actually get nice gray level steps on the color bars when you turn the color down?

[SwizzyMan]

Yes, I just need to adjust the brightness.

[Hagstar]

With my CTC4 I ended up getting all NOS tubes which I've never done for any radio or TV. BUT these early color sets run them too hard. I can't get stable color with any of my used tubes in the chromiance section even though they test fine on the Hickok.

[SwizzyMan]

Originally Posted by Hagstar

With my CTC4 I ended up getting all NOS tubes which I've never done for any radio or TV. BUT these early color sets run them too hard. I can't get stable color with any of my used tubes in the chromiance section even though they test fine on the Hickok.

Good idea John. I did suspect the 12BH7 r-y demod. Tested fine. I'll pick a whole new set except for h-out and he circuit tubes.

[SwizzyMan]

Could this be a weak red gun? Id think if the red was weak of course shades of certain colors that use red would be way off. I just need to know if I should start hunting for another tube.

[miniman82]

hook up a CRT tester and find out

[benman94]

That set has so many major problems that the LEAST of your worries should be the condition of the CRT. Replacing the CRT is not going to be some magical cure for your issues. Put it on a tester if you like, but even a good tube would produce a terrible picture when driven by that chassis.

[SwizzyMan]

I didn't believe it would be a magical cure, but the red gun tests really weird and I thought that it might be a pretty weak gun and in result colors that use red would be either not present or incorrectly colored. This set is a real pain so far. But I'm going to just start with a fresh brand new set of tubes and go from there. Something tells me I will probably be doing some alignments . The red gun on the CRT tests good at first but then 1 second later the needle swings pretty erratically but the swinging stay within the ? And good range. Both other guns do this but not nearly as much. And I've found also that the red screen control does almost nothing too, I'll have to check it.

[Electronic M]

Does your CRT tester's instructions mention how a gassy tube should test....It might be getting gassy.

[SwizzyMan]

Originally Posted by Electronic M

Does your CRT tester's instructions mention how a gassy tube should test....It might be getting gassy.

No it doesnt. It did this when I got it about 4 months ago so if it's getting gassy it's extremely slow and it isn't gassy enough to kill the picture. I don't think it's gassy.

[benman94]

The fact that you aren't seeing red doesn't automatically point to the red gun of the CRT. You could (and almost assuredly do) have a matrix or demod issue. My CT-100 had problems in the red adder that completely killed any red on the screen; the 15GP22s strongest gun was actually the red gun however.
If the tube was going gassy, I strongly suspect you'd have at least major focusing issues, etc.
Get the chassis working first, then worry about the CRT. Even if the CRT is garbage, I'd finish the restoration and wait for a clunker CTC-5 with a good 21AXP22 to surface. There's little point in having an operational CTC-4 without a good 21AXP22, and you'd be throwing good money after bad by putting another 21FBP22 or 21FJP22 in it.

[SwizzyMan]

Started to replace some tubes. I also tested the tubes I was replacing and noticed that the 12BH7 R-Y Demod tube has a cathode short. This could explain the absence of red. This short didnt show up on the hickok 600a, but it did show up on the WT-100a. The WT-100 has an extremely sensitive shorts test so I guess it was able to pick it up.

[SwizzyMan]

I've been thinking about stealing the 21ax out of the 5 and putting it in the 4. Does anyone have a glass retrofit kit for the 5? I'm not sure it's a good idea really, but I am looking for authenticity.

[old_tv_nut]

I hope you can find a real retrofit kit, but they are scarce. I never found one. I used some CTC-7 pieces plus miscellaneous jury-rigged hardware to put a glass tube in my 5 until I could get a 21AX. Regarding authenticity, there is no visible difference from the front, and you can do it without destroying any part of the 5 (just save a few parts like the plastic funnel and edge magnets in a box), so if/when you get another 21AX, you can always reverse it.

[Electronic M]

Don't know if it would help, but I do have a spare CRT mount assembly out of something like a CTC-15 that I'd sell.