1957 Muntz 721CV color set found in northern California

[Steve D.]

After viewing the various photos of both sets, each having a tube chart that is similar to the CTC-5 Special/Super chassis. Except for the tuner. I suspect Chris has the original Muntz chassis in his set. I see in Chris' post #22 the photo of the chassis front panel that has the convergence & screen controls ect. also shows the empty holes that RCA used for their user controls, which Muntz has grouped with the tuner. John's set may have had a Deluxe chassis installed to replace the Special/ Super chassis at one point. John's tuner also from a CTC-5 Deluxe side mounted model. Hence, the holes cut in the cabinet side for the channel selector. John's user controls are also under the screen and have the 6 controls as on the CTC-5 Deluxe chassis. Which would explain the holes drilled in the wood panel between the hortz. and vert. controls and the crude handwritten legends. There are other differences on both sets that would require a SAMS, if they had one, to futher verify what's original and what's not.

-Steve D.

[ChrisW6ATV]

Here is the bad news: The 21AXP22A CRT has open filaments.

The CRT appears to be the original, made in the 13th week of 1957 based on the label on the CRT connector. Well, I will at some point go looking for a usable CRT for this set. It is a gray-face type (as may be all AXP's?), but I remember seeing a discussion that some newer ones (early FBP's?) were also gray. I know conversions were done with glass CRTs, but I would not do that on this set unless it was a completely reversible (and ideally, invisible) process. Have any of you done such a task?

[Steve D.]

Chris,

My CTC-5 has been converted to a 21FB tube. This was done before I bought the set many years ago. The conversion kit supplied by RCA replaces the insulating boot and most 21AX mounting hardware with a metal disc that surrounds the 21FB bell and has latches welded to it with struts that extend to the existing mounting hardware behind the mask. I have never seen these RCA conversion kits available on e-bay or anywhere else. Certainly finding a good 21AX would be the best solution.

Best,
-Steve D.

[NewVista]

Originally Posted by Steve D.

Chris,

My CTC-5 has been converted to a 21FB tube. .

Would you have a picture of this mount as I need to do similar (install all glass roundie)
for my Whitby Deluxe. I know it won't be easy.

[Steve D.]

New Vista,

sending you an e-mail via VK.

-Steve D.

[old_tv_nut]

Originally Posted by ChrisW6ATV

Here is the bad news: The 21AXP22A CRT has open filaments.

The CRT appears to be the original, made in the 13th week of 1957 based on the label on the CRT connector. Well, I will at some point go looking for a usable CRT for this set. It is a gray-face type (as may be all AXP's?), but I remember seeing a discussion that some newer ones (early FBP's?) were also gray. I know conversions were done with glass CRTs, but I would not do that on this set unless it was a completely reversible (and ideally, invisible) process. Have any of you done such a task?

You can do a reversible glass CRT replacement by removing and saving all the metal tube hardware and jury-rigging whatever is needed to mount the glass tube, screwing it to the existing bezel. From the front, it fits perfectly.

[Mal Fuller]

I'm not sure and a basing diagram was useless in confirming or denying how the filaments of the three guns are internally connected in a 21AXP22 and later roundies. My memory says that they are in parallel, not series. If that's true therefore, it's very improbable that the filaments in all three guns are open.
Hence, if all three filaments are dark, that would seem to indicate that the two solder connection on the base pins need to be re-soldered.
The tube might not be beyond hope.

[Eric H]

Originally Posted by Mal Fuller

Hence, if all three filaments are dark, that would seem to indicate that the two solder connection on the base pins need to be re-soldered.
The tube might not be beyond hope.

Or more probable for a 21AXP, the tube has gone to air and they burned up.

[Mal Fuller]

It just crossed my feeble mind that this 21AXP22 could also have gone to air, frying the filaments. However, it would certainly pay to be sure. I guess Eric and I wrote our posts at nearly the same time.

[old_tv_nut]

here are photos of how I used a CTC-7 mounting ring and some hardware store parts:

http://www.flickr.com/photos/4200284...7627018247265/

[NewVista]

Originally Posted by old_tv_nut

here are photos of how I used a CTC-7 mounting ring and some hardware store parts

Got the job done neatly! Gives me some ideas.

[ChrisW6ATV]

Originally Posted by Mal Fuller

It just crossed my feeble mind that this 21AXP22 could also have gone to air, frying the filaments. However, it would certainly pay to be sure. I guess Eric and I wrote our posts at nearly the same time.

This is my main fear, yes. I will have to remove the neck accessories and clean the neck to see the getters as the next step. The CRT base is tight, and I was pretty sure I could see the wires at the end of each pin, so I doubt it is something nice and repairable like a loose wire.

[ChrisW6ATV]

Originally Posted by old_tv_nut

here are photos of how I used a CTC-7 mounting ring and some hardware store parts:

http://www.flickr.com/photos/4200284...7627018247265/

That is a nice mount for the CRT. Did you use the CTC-5's original yoke, and if so, how did you anchor it since it normally is held by the plastic shroud? I once worked on an early color set that had had its 'AXP replaced by a 21FBP22, and the (original) yoke was basically loose on the neck. I made a bracket that was suspended from under the top of the cabinet to hold it in place and allowed its position to be adjusted.

[Mal Fuller]

The RCA conversion kit supplied a later style back yoke cover to go on the CTC-5's yoke. It seems that I remember that it was a bit ill-fitting or a little hokey in some way, but it did the job.

[old_tv_nut]

Originally Posted by ChrisW6ATV

That is a nice mount for the CRT. Did you use the CTC-5's original yoke, and if so, how did you anchor it since it normally is held by the plastic shroud? I once worked on an early color set that had had its 'AXP replaced by a 21FBP22, and the (original) yoke was basically loose on the neck. I made a bracket that was suspended from under the top of the cabinet to hold it in place and allowed its position to be adjusted.

The yoke is loose on the neck - I will take it off in case of any big moves, to avoid possibility of breaking the tube. But convergence/centering/purity wise it's working fine. I can't remember now if the internal plastic sleeve has some expanders stuffed in it (probably at the top) to keep it from tilting backwards, and I can't see past the convergence coils to see what's there at the moment. I do know it slides pretty easily.