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  #16  
Old 06-23-2017, 04:21 PM
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Does the serial number RH 17516 appearing on the 21CYP22A have any significance?



Edit: typo fixed
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Last edited by etype2; 06-23-2017 at 04:57 PM.
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  #17  
Old 06-23-2017, 04:51 PM
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[quote=etype2;3185797]does the serial number rh 17516 appearing on the 21axp22a have any significance?


21cyp22a

.
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  #18  
Old 06-23-2017, 04:58 PM
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[QUOTE=WISCOJIM;3185799]
Quote:
Originally Posted by etype2 View Post
does the serial number rh 17516 appearing on the 21axp22a have any significance?


21cyp22a

.
Opps. Fixed. :-)
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  #19  
Old 06-23-2017, 09:45 PM
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Quote:
Originally Posted by Findm-Keepm View Post
Just curious, but were any of the CRTs prefixed with RE? There was a time in the TV repair world where "RE" tubes were shunned out of ignorance, with technicians believing the tubes to be "rebuilt" tubes vice those with the newer/replaced Rare Earths, with increased brightness and deeper reds. They made the scene i the 1960s, with RCA and Sylvania touting the improve characteristics of the tubes.

http://www.americanradiohistory.com/...-Page-0026.pdf

The funniest part is that rare earths were already in use, it's just the shift to different rare earths (and marketing) that brought about the prefix.

Sylvania advertised the tubes and mentioned the prefix, but still many techs stuck to the ignorant idea that they were rebuilds. Somewhere there is a Jack Darr or Art Margolis article about the fallacy/idiocy...

When I started back in the 1970s, all I ever saw was rebuilt tubes from Channel Master and Empire Video, so the tube labels with any identifying info were long gone..
No. The 15G through 21CYP22A were never manufactured in a later rare-earth type. The 21FBP22 was interchangeable with all of the later 21 inch tubes, so it was possible to stick a rare earth tube in a CTC-11, but I purposely tracked down the oldest FB I could find thus ensuring it could only be a sulfide tube.

The rare earth tubes did bring the red nearly back to '53 red, but the obssesion with deeper reds seems unwarranted to me. The major shift was in the green, and that was never reversed or corrected. Orange, yellow, skin tones, etc all depend on both red and green phosphors lighting up. A yellowish green phophor can make for a nasty orange or yellow even with a good "deep" red phosphor.

All of these shifts and butchering of NTSC's gorgeous color gamut all in the search for slightly brighter pictures. For shame...
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  #20  
Old 07-18-2017, 11:32 AM
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Quote:
Originally Posted by benman94 View Post
I've done tests with a colorimeter on the following tubes:
  • 15GP22
  • 21AXP22 (green screen)
  • 21AXP22A (paper white screen)
  • 21CYP22 (grey-blue screen)
  • 21CYP22A (grey-blue screen)
  • and finally an early 21FBP22 (puke green screen)

The blue shifts slightly toward violet and away from a more cyan color over the years, the red also shifts toward orange, but the greatest shift is in the green. The P1 "Kelly greens" are gone by the time you get to the 21AXP22A; the green phosphor is already substantially more yellow, and the trend gets worse with time.

The persistence of the phosphors seemed to vary somewhat as well, with some tubes, like the 21CYP22A having a bit more lag (something I've noticed, and apparently Pete Deksnis has as well according to his website).

The strange red phosphor I'm referring to in the 21CYP22A blows out to orange with high beam current more readily than the non-A version, at least in my experience. But, the 21CYP22A is much, much brighter than the non-A version. You pays your money and you takes your choice.

I'm unusually picky about how my color sets are set up however; I always drag out a colorimeter to set the white point, check grey-scale tracking, and I ONLY watch my sets in a blackened room. If you're eyeballing the grey-scale and watching in a room with any light, you more than likely will never notice the smaller differences between the CRTs, only the larger ones (say the difference between a 15G and a 21FB).
Keep in mind these sets were never designed to run at high brightness. All the older crt's before rare earth would lose red upon extreme brightness. Also crt's during that period were all part of the development process and in my mind they all culminated with the CTC 16. After that point you move into the 25apx22 and others and then came all the I don't care sets.
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  #21  
Old 07-18-2017, 12:21 PM
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The main fix for the green shift towards yellow is an increase in R-Y gain, which should be done as a linear matrix in the camera, as PAL and HDTV do. Unfortunately NTSC never standardized the new green and set makers each applied a demod change of their own choosing. While this fixed skin tones, it resulted in overdriving reds due to the nonlinear CRT gun current vs voltage.
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  #22  
Old 07-18-2017, 12:24 PM
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Originally Posted by oldtvman View Post
all culminated with the CTC 16. After that point you move into the 25apx22 and others and then came all the I don't care sets.
Your forgetting the CTC-20 roundy....That was the last RCA roundy.
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  #23  
Old 07-18-2017, 01:07 PM
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Based on the tests and observations of benman4 and others, would it be possible that the same phosphor compounds that were used in the 15G also have been used in the non-A 21AX? I have often felt that it might be so, based on the color reproduction of my non-A 21AX, as installed in my CTC-4. See avatar.

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  #24  
Old 07-18-2017, 01:25 PM
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It's my understanding that the phosphors are the same in the two tubes you mentioned.
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  #25  
Old 07-18-2017, 01:54 PM
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Quote:
Originally Posted by stromberg6 View Post
Based on the tests and observations of benman4 and others, would it be possible that the same phosphor compounds that were used in the 15G also have been used in the non-A 21AX? I have often felt that it might be so, based on the color reproduction of my non-A 21AX, as installed in my CTC-4. See avatar.

Kevin
There are three variants of the 21AXP22:

The exceedingly rare "green screen" 21AXP22 with identical phosphors to the 15GP22, 15HP22, and 19VP22.

The typical "paper white" 21AXP22 found in most CTC-4s and LB-962 clones.

And finally the 21AXP22A, all of which have the same paper white phosphor as the second 21AXP22.

The "paper white" screen is still markedly close to the 15GP22 though, as are both variants of the 21CYP22; the shifts went haywire with the introduction of the 21FBP22. The greens are just a little more yellow, and the reds a touch more orange from mid-55 to 1960ish. No true Kelly greens or overtly ruddy complexions.
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  #26  
Old 07-18-2017, 02:00 PM
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Quote:
Originally Posted by oldtvman View Post
Keep in mind these sets were never designed to run at high brightness. All the older crt's before rare earth would lose red upon extreme brightness....
And that's precisely why I watch my roundies in a blackened room. Not subdued lighting, black-out curtain dark...
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  #27  
Old 07-18-2017, 02:39 PM
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This is the red on our 21AXP22 with low saturated greens.



This is the red after adjusting for higher saturation of green.

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  #28  
Old 08-15-2017, 02:00 AM
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On the hunt for new flyback for CTC-7

On the hunt for new flyback for RCA CTC-7.

Latest from Mike on the restoration of Ed Reitan's CTC-7 Worthington.

https://visions4netjournal.com/2017/...-page-three-a/

"Bad news. When I removed the cage and was able to see where the centering control is, I noticed that someone had been there “before me”. The capacitors that are related to this problem have been changed and the Horizontal centering control is good. I also now, have a good explanation as to why the control was responding as it was. The C1 Winding on the Flyback transformer is OPEN. In the pictures it is the Second winding DOWN as you look at the center of the photo. I was able to tug gently on the insulation of the second wire down and with NO EFFORT AT ALL, the insulation came off and the broken wire was exposed. This wire is only a bit bigger than a human hair. Please find photo. You can see the newly replaced big orange capacitors where someone has been before me. I was able to scrape (with a small razor knife) The oxidation from the wires on one side. I could not get to the other side without fear of the wires completely falling apart so I had to be careful. I tinned the wires with my soldering iron and then carefully lapped them together to re-establish the connection. I had to put on my “Big Boy ” glasses to see this well enough to do the repair. You can see the repaired wire in the third photo LONG story SHORT is this set needs a new flyback transformer. The RCA part number according to the Sams Photofact is 106359 and the 4th photo is a good shot of the flyback transformer for reference. I will fire this set up again tomorrow and see if the control is working properly. This will be done with the cage removed so I can’t leave it on for long that way because of the way it sits on the bench. It gets support from the cage being there and with the cage removed it is very unstable on the bench. . But at least I can determine if the control is working properly and then I can continue with my modifications of the cage for the installation of a fan and increased ventilation. I can guarantee that the life of this flayback transformer is very limited. There is corrosion on the fine small wires where they go in to the transformer. This is no doubt due to heat from hours of use over the years.

Regards, Mike

Author:

Hi Mike,

Wow! Talk about delicate surgery! Excellent shots. I know you worked hard to show this detail in photography and even harder to make sure the whole thing did not collapse. Thank you. On the hunt for a new flyback. If it’s okay with you, I think the chassis should stay with you until we find a new flyback.

Marshall"

If anyone can lead us to finding a replacement would be greatly appreciated. Thanks.
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Last edited by etype2; 08-15-2017 at 02:03 AM.
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  #29  
Old 08-15-2017, 08:29 AM
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There was a new old stock CTC-7 flyback on eBay not too long ago. Went for about $200 as I recall. Hopefully you find one..
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  #30  
Old 08-15-2017, 09:29 AM
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If the repair was successful it may have as much as decades more time left on the fly, assuming temp and current can be kept under control.

Part of me wonders if the copper corrosion is natural. I know this example is a good 30 years older, but I've done ~3-4 Philco 60 chassis cathedral radios (2 more waiting in the wings) and 2-3 of their loss leader cousins the 80 chassis (2 of those waiting my bench also), and all but one of them (a 60 chassis) had either the antenna transformer, osc transformer or both with corroded open windings (and these windings have a coating besides the wire lacquer sealing?/holding them to the forms)...Only one had the problem in the lead-in, the rest were mid winding...Sometimes with multiple opens. The first ones I fixed in a similar fashion to what your tech did, the rest especially the ones with multiple opens I just rewound the ~<20 turns with phono pickup wire. All these sets were ones with good original cabinets, not barn dwellers, yet still were like that.
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