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Old 07-17-2016, 05:19 PM
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SwizzyMan SwizzyMan is offline
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CTC-4 Director 21

just picked up this nice CTC-4 director down in West Palm. The set has a big history and has been heavily modified. This set originally came from Connecticut. It was acquired by its previous owner (he was a repairman) when a customer decided that the set was too expensive to get repaired and they left it. It eventually moved down here to Florida. The previous owner was an experienced Ham radio operator. I was invited to take a look around his house while we were picking the set up, his house was full of receivers and a couple FM transmitters he built himself with many other pieces of tube equipment. I originally heard about this set through my wanted ad in the classifieds here. The original price was $6000 BIN and $3000 to bid on it. Eventually, it made its way to $500 after I offered $500 for it. The first thing that I noticed when i saw it on ebay was that it had a glass 21FBP22 instead of the original 21AXP22 crt. This didnt bother me much at all. While it may decrease its value, the FB will have a much better chance of surviving all these years without leaking. I was able to test the CRT today and the results were a bit discouraging, the cutoff on almost all the guns was just barely under the box on my CR-31A, and to make matters even more confusing each gun tested fine for a few seconds on the tester, but then the needle starts swinging erratically and upward. I thought I read somewhere that these results may indicate a gassy tube, but this doesnt make any sense since I can get a full raster, but the tube seems kind of dim and the red color seems to the least bright of the three colors. I'm not sure if I should zap the three guns with a rejuve or what. I ran the set for about five minutes monitoring the current draw just so I could get a baseline. I got a decent black and white picture, but when I turned the color on I got a lot of interference in the form of small streaking horizontal lines. I also noticed the colors are pretty rough with no signs of light blue and pretty dim reds. At the end of the five minute run I heard a loud pop (sounded like a firecracker).Current draw stayed fine. I immediately shut the set down. I think a paper cap finally gave out causing the loud pop. This is going to be a long project , but I think I can handle it.
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File Type: jpg DSC_1014.jpg (48.7 KB, 117 views)
File Type: jpg DSC_1013.jpg (53.6 KB, 169 views)
File Type: jpg DSC_1011.jpg (74.7 KB, 126 views)
File Type: jpg DSC_1010.jpg (84.9 KB, 171 views)
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  #2  
Old 07-17-2016, 05:21 PM
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SwizzyMan SwizzyMan is offline
Restoring an admiral c322
 
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File Type: jpg DSC_1017.jpg (77.0 KB, 79 views)
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  #3  
Old 07-17-2016, 05:40 PM
wiseguy wiseguy is offline
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you should Discharge the HV from the CRT completely before testing on a CR-31, this would cause Erratic Testing, the pop you heard could have been a HV discharge to chassis Ground since its been modified for a newer tube, I went thru this on my ctc-4 before the CRT got rebuilt when hawkeye was in business, there is also some mods in the Gun Drive Circuit to make these newer tubes "run" correctly, color Temp is a bit different
Good Luck!

Last edited by wiseguy; 07-17-2016 at 05:47 PM.
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Old 07-17-2016, 06:13 PM
old_coot88 old_coot88 is offline
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The loud pop could easily have been a HV arc from the anode button to the shield (where somebody has made a big cutout in the shield). In fact, in your 5th photo there's what looks like an arc track from the button to the shield.

"rejuvving" the jug should be the absolute last resort.
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Old 07-17-2016, 08:26 PM
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Phil Nelson Phil Nelson is offline
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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 . . . ?
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Old 07-17-2016, 08:38 PM
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Quote:
Originally Posted by Phil Nelson View Post
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!
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Old 07-17-2016, 09:31 PM
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SwizzyMan SwizzyMan is offline
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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.
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  #8  
Old 07-19-2016, 07:14 PM
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miniman82 miniman82 is offline
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Same here, came on a spare jug I bought and I don't need it. Got the metal parts too, they aren't hacked.
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Old 07-19-2016, 07:21 PM
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As soon as I get some money. I'm buying an ax if I can even find one. I really wish I had an ax for this set. But can anyone answer my question on the reasons for the orange discharge in my glass 21FB?
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Old 07-19-2016, 08:37 PM
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Quote:
Originally Posted by SwizzyMan View Post
But can anyone answer my question on the reasons for the orange discharge in my glass 21FB?
Just a very wild guess... perhaps some red phosphor from the photo-deposition screen process did not get cleaned completely off of the panel skirt. and is being excited by secondary electrons emitted from the shadow mask.

jr
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Old 07-19-2016, 07:26 PM
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Who cares, it makes an image.
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Old 07-19-2016, 07:47 PM
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Phil Nelson Phil Nelson is offline
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I'd love to find a 21AXP22 for my CTC-4, but they don't grow on trees. Meanwhile, a glass CRT lets me watch the set. Without viewing two CTC-4s side by side (one with 21AX, the other with glass), I'm not sure my uneducated eye could tell one from the other, anyhow.

Sorry, I don't have a good guess about the orange discharge inside your CRT. What's the condition of the CRT's aquadag coating? All in good shape and securely connected to ground? Does the dancing glow move in concert with arcing sounds? Or is completely independent?

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html
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Old 07-19-2016, 08:00 PM
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SwizzyMan SwizzyMan is offline
Restoring an admiral c322
 
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Quote:
Originally Posted by Phil Nelson View Post
I'd love to find a 21AXP22 for my CTC-4, but they don't grow on trees. Meanwhile, a glass CRT lets me watch the set. Without viewing two CTC-4s side by side (one with 21AX, the other with glass), I'm not sure my uneducated eye could tell one from the other, anyhow.

Sorry, I don't have a good guess about the orange discharge inside your CRT. What's the condition of the CRT's aquadag coating? All in good shape and securely connected to ground? Does the dancing glow move in concert with arcing sounds? Or is completely independent?

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html
Dag is perfect.Dusty but in nice shape. The dancing orange glow is completely independent. It only occurs on the lower areas and sometime the top areas at the left side of the CRT. While I'm no longer concerned about my CRTs health I am still wondering what this is or if it does mean trouble. I will also mention that the external graphite coating is properly grounded.
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Old 07-19-2016, 07:57 PM
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Is there a ground strap on the bracket that holds the crt ?
Sorry it was mentioned already by Phil Nelson .
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Old 07-19-2016, 08:58 PM
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Shouldn't be possible, the shadow mask is spot welded to a frame which has a lip on it that extends back towards the electron gun specifically to prevent stray electrons.
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