CTC-4 Director 21

[Phil Nelson]

Definitely do not rejuvenate the CRT at this point. Too easy to kill the tube, and what you're seeing on the screen may be normal for a CTC-4 that's chock full of bad caps. A working television will tell you more about a CRT's condition than any tester.

I agree with old_coot88, that pop sound could be arcing, and the cutout in the CRT metal retaining ring is an obvious place to look. If you run the TV briefly in a completely dark room, you might even see the zap occur along that dark track seen in the photo.

When I installed a glass CRT in my set, I made a smaller cutout in the ring, but I also covered the nearby edges with cambric insulating tape rated for 90KV. More about all that in:

http://antiqueradio.org/RCACTC-4ColorTelevision.htm

You are right to think of this as a long term project. Be patient and it will all get done. CTC-4s don't come along very often, so enjoy working with this one while you can.

Have fun!

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

P.S. What's in the little metal project box? Looks like a relay and a tube on top . . . ?

[SwizzyMan]

Originally Posted by Phil Nelson

Definitely do not rejuvenate the CRT at this point. Too easy to kill the tube, and what you're seeing on the screen may be normal for a CTC-4 that's chock full of bad caps. A working television will tell you more about a CRT's condition than any tester.

I agree with old_coot88, that pop sound could be arcing, and the cutout in the CRT metal retaining ring is an obvious place to look. If you run the TV briefly in a completely dark room, you might even see the zap occur along that dark track seen in the photo.

When I installed a glass CRT in my set, I made a smaller cutout in the ring, but I also covered the nearby edges with cambric insulating tape rated for 90KV. More about all that in:

http://antiqueradio.org/RCACTC-4ColorTelevision.htm

You are right to think of this as a long term project. Be patient and it will all get done. CTC-4s don't come along very often, so enjoy working with this one while you can.

Have fun!

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

P.S. What's in the little metal project box? Looks like a relay and a tube on top . . . ?

Thanks Phil! I'll try and keep watch on that area suspect to arcing. The little project box is actually a soft start module. It lets the tubes fully heat up before applying any voltage to them. The same concept is shared on your CTC-7, but this was one of the modifications the previous owner installed. I think its pretty nifty!

[SwizzyMan]

Cant tell if this is a HOT cathode current meter or what. I dont think it is since the meter only has a range of 10 MA and normal cathode current is atleast 100MA.

[Electronic M]

Originally Posted by SwizzyMan

Cant tell if this is a HOT cathode current meter or what. I dont think it is since the meter only has a range of 10 MA and normal cathode current is atleast 100MA.

It could be a cathode current meter with the appropriate shunt resistance in parallel with it to scale the current it receives to the appropriate range...

[old_coot88]

Originally Posted by SwizzyMan

Cant tell if this is a HOT cathode current meter or what. I dont think it is since the meter only has a range of 10 MA...

That meter is one milliamp full-scale. So it's probably wired to measure the HV regulator current. If it's measuring H.out cathode current, it'll have a low value shunt across it.

...and normal HOT cathode current is at least 100MA.

Normal H.out cathode is closer to 200 ma.

[SwizzyMan]

I wonder if the CTC-4 has those pesky HV issues like the CTC-5 does? I really hated dealing with that in my 5. And how is its performance? Hopefully better than my 5 too.

[miniman82]

5 is the only one with weak HV, you won't have any trouble getting a full 24/25 KV out of this set.

[SwizzyMan]

I was doing another current monitoring power up to keep an eye on the possible arcing area from crt to yoke shroud/housing. I discovered something very interesting and possibly damning. There is a strange orange almost neon-like discharge between the very edge of the internal coating to the shadow mask assembly im assuming in the crt. Now I dont suspect this to be oxygen molecules since the color of the discharge is orange not purple, but could this mean my CRT is in trouble? I don't think the tube is gassy since I can still get a nice, bright and full raster on the screen. I've noticed the glow kind of likes to jump around like some neon bulbs do (like electricity in a decorative neon flame bulb trying to find the path of least resistance). This is concerning me since I have never EVER seen anything like this. Your thoughts?

[bigaudioal]

Originally Posted by miniman82

5 is the only one with weak HV, you won't have any trouble getting a full 24/25 KV out of this set.

When working with my CTC-5 last week I noticed that all the service literature I have says between 19.5 - 22.5kV at the CRT anode. My CTC-5 is putting out exactly 20kV.

Why do I constantly see folks complaining about the CTC-5 not putting out 25kV when all the original service literature says lower than 25kV for this set is normal?

SAMS for early CTC-5 says 22.5kV
RCA Original Service Manual says 19.5kV
RCA Original Setup Manual says 20kV
SAMS for late CTC-5 says 22kV

See attached snip-its from some of that literature.

Just wondering as I have limited experience with vintage color sets.

Thanks.