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-   -   Wanted: Dead 21FJP22 or similar (http://www.videokarma.org/showthread.php?t=262879)

jeyurkon 10-22-2014 09:42 AM

Wanted: Dead 21FJP22 or similar
 
Does anyone have a dud 21FJP22 or similar color crt with a 2" neck they'd be willing to donate?

I need something to practice on before installing a gun in a 15GP22 CRT. You can see what I've done so far at 15GP22 Project

I'm at the stage of having produced an all glass 15GP22 envelope that has been leak tested. I need to practice using a CRT lathe to install the gun before I install the expensive 15GP22 rebuilt gun.

You might end up with a good CRT, or not.:scratch2: But you'll have contributed to the project.:thmbsp:

John

Username1 10-22-2014 03:21 PM

I would imagine those with a dud 21" color tube would be waiting for an actual chance
to get their tube rebuilt and have a good one returned for real, and not up for
experimentation.....

I have seen your all glass 15g project page, and it's pretty impressive, I think it's a good
idea to replace the more troublesome metal parts of the tube. (metal glass joints)

Attaching the new gun to the envelope should be pretty much a down hill endeavor...
and alignment should not be that hard as compared to everything you did up to now...

I think you should just go ahead and put it together.....

How did you get a rebuilt gun, and how much...?
Or did you build it...?

Those 15g tubes have failed during baking and cooling on rebuild attempts, what
have you looked at as far as the heating cooling cycle for it this time...?

Without the metal rings in contact with the glass the face part of the tube
should be less of a concern.....

Are you going to vacuum it and seal it using the equipment at the museum or
do you have your own equipment...?

You have a new gun to put on that 21FJP22 to do a rebuild...?
Or you just gunna cut the old one off and put it back on....?

I see you updated the glass 15g page since I first saw it... It looks like
you had too much heat on that last picture of a pinch off test... Is that
the case...? You might need a heat shield above the pinch off point.

Seems to me you should be able to experiment on a long piece of 2" tube
glass and a pinch off connected to it with a flat glass all attached together,
welded or fritted....

.

Eric H 10-22-2014 04:31 PM

I have a couple of them, getting it from CA to MI is the problem.

NoPegs 10-22-2014 04:39 PM

Quote:

Originally Posted by Eric H (Post 3117738)
I have a couple of them, getting it from CA to MI is the problem.

Getting the successful outcome back to Cali is harder. :scratch2:

Eric H 10-22-2014 05:35 PM

John, The original ring was made up from two pieces of metal welded together and that's where the leaks occur right?

I had an idea, maybe not a good one but thought I'd throw it out.

Instead of going glass to glass perhaps you could fashion a new ring out of a solid piece of metal, it could have a lip on either side to align the glass and it would also provide more sealing surface for the frit to adhere to. Plus you could still use it for the HV connection, it would also keep the dimensions correct.

Perhaps this isn't feasible due to expansion characteristics but I thought I'd suggest it.

jeyurkon 10-22-2014 10:04 PM

Quote:

Originally Posted by Username1 (Post 3117733)
I would imagine those with a dud 21" color tube would be waiting for an actual chance
to get their tube rebuilt and have a good one returned for real, and not up for
experimentation.....

I have seen your all glass 15g project page, and it's pretty impressive, I think it's a good
idea to replace the more troublesome metal parts of the tube. (metal glass joints)

Attaching the new gun to the envelope should be pretty much a down hill endeavor...
and alignment should not be that hard as compared to everything you did up to now...

I think you should just go ahead and put it together.....

How did you get a rebuilt gun, and how much...?
Or did you build it...?

Those 15g tubes have failed during baking and cooling on rebuild attempts, what
have you looked at as far as the heating cooling cycle for it this time...?

Without the metal rings in contact with the glass the face part of the tube
should be less of a concern.....

Are you going to vacuum it and seal it using the equipment at the museum or
do you have your own equipment...?

You have a new gun to put on that 21FJP22 to do a rebuild...?
Or you just gunna cut the old one off and put it back on....?

I see you updated the glass 15g page since I first saw it... It looks like
you had too much heat on that last picture of a pinch off test... Is that
the case...? You might need a heat shield above the pinch off point.

Seems to me you should be able to experiment on a long piece of 2" tube
glass and a pinch off connected to it with a flat glass all attached together,
welded or fritted....

.

I'd be installing a new gun in the 21FGP22 or whatever, not reinstalling the old one. And this would come after I've practiced installing a dead gun in a dummy 2" tube for practice. Basically what you said.

I've run the 15GP22 through a number of heating cooling cycles without any damage to the phosphor screen plate, the shadow mask, the face plate, or funnel. My oven is much more controlled than Hawkeye's and has extremely uniform temperature. I designed it for this project.

Steve loaned me one of Hawkeye's CRT lathes. I will use my own oven and one of Hawkeye's diffusion pumps and mechanical pumps.

I hadn't realize there were additions to my report recently. I didn't intend for the video or the tube you see to be added. I haven't done any pinch-off tests. The photo that you're referring to is a developmental Dumont that came from their glassblowers estate and I won it in an auction from Harry Poster. Harry didn't package it well and the tubulation broke in shipment.

I used the photo in a email conversation among a group of us to show an alternative method of producing a stem for B/W tubes since we might not be able to obtain them anymore. I don't think we'll have to go that route, but it's a possibility. Ingo Kubbe suggested the method but it was difficult for others to understand what he was suggesting, so I sent the photo.

Sorry for the confusion. I'll ask Steve to remove it since it's not related to the 15G in any way.

I had the 15G gun rebuild by eBeam Inc. It was something over $300

John

jeyurkon 10-22-2014 10:20 PM

Quote:

Originally Posted by Eric H (Post 3117743)
John, The original ring was made up from two pieces of metal welded together and that's where the leaks occur right?

I had an idea, maybe not a good one but thought I'd throw it out.

Instead of going glass to glass perhaps you could fashion a new ring out of a solid piece of metal, it could have a lip on either side to align the glass and it would also provide more sealing surface for the frit to adhere to. Plus you could still use it for the HV connection, it would also keep the dimensions correct.

Perhaps this isn't feasible due to expansion characteristics but I thought I'd suggest it.

Some of the things I said in the beginning of the report are wrong. The glass isn't Corning 0120. I will make a correction during my next ETF presentation. Nick Williams or I will explain what glasses were actually used in the 15G. They do match the 430Ti alloy properly.

eBeam had suggested an arrangement similar to what you describe, but it would have been a real glass to metal seal done by a glass company out west. He referred it to them but they would never reply to my inquiries.

The frit to metal would only work for a small number of the 15G's. The faceplate doesn't always seperate from the Ultor ring cleanly. Bob G has a method that will probably work, but then you still the problem of cushioning the contact areas under vacuum. There's tons of total pressure pushing the pieces together that have to be support by the contact area. It wouldn't be perfectly flat and the pressure from the high points would fracture the glass. That's why RCA put that corrugated aluminum crush ring between the two pieces. Even with that, that's probably the real reason for the leaks developing. It wasn't always sufficient.

Using frit to join glass to glass solves that problem because it becomes one piece.

I'd like to find someone closer with a dud CRT. I'd hate to have it break in shipping in either direction. I do expect the rebuild would work for the CRT, but if I do make a non-recoverable mistake I'd rather do it on something more common that a 15G.

There may be other methods that work, this is the one that I chose to pursue after running through several options and listening to suggestions of others.

John

Username1 10-22-2014 10:21 PM

John;

Thanks for writing in such detail....

It sounds like you have quite the setup, and quite the investment in this project.
And thanks for detailing what you are planning for the dud 21" tube. I would think
anyone would volunteer a dud happily knowing you have a good plan set up and
very good chance of success....

I sure hope you add as much detail as possible about all the work you continue to
do on the all glass 15g, I enjoyed reading it all.... Several times...

Have a great night.

.

DaveWM 10-22-2014 11:08 PM

I have a 21CYP22 that I have been hanging on to in hopes of getting it rebuilt, it has an open filament on one gun. May have a 21FJP22 somewhere around here that is VERY weak.

only problem is distance, Orlando.

Username1 10-23-2014 07:22 AM

Well just build a wood box to ship the tube similar to the cardboard ones used for
smaller tubes that you can screw down supports that hold the tube and do not touch
the neck at any point. Than ship it using a freight company.

Seems with all you put into your rebuilding effort designing a box and a few items to
hold a 21" round tube secure enough for a trip across country should be within your
ability.

You know I think there are contests where kids build containers to keep an egg from
being broken when dropped off a 2nd floor building.... Besided you already can see from
the NOS tubes that come in boxes the minimum you need... You just have to make it
2014 proof..... Unfortunately I bet a lot of stuff is treated with much less care today...

On the plus side I got a picture tube in a NOS original box off ebay a year ago and it
arrived with the 50 year old box still looking great !

.

jeyurkon 10-23-2014 10:50 AM

A small bakelite set was shipped to me and arrived in small pieces, through FedEX. Then I won an auction for a 12LP4 and it was shipped to me in a similarly old box, but marked "Glass, Implosion Hazard" and the FedEX guys showed up in a U-Haul with two of them carefully carrying it from the truck.

I'm surprised they didn't charge the shipper a Hazardous Materials fee because of the label.

Yes, I could build a box, but not having such a CRT in hand to fit it would make it difficult for me to do it at my end.

jeyurkon 10-23-2014 10:59 AM

Quote:

Originally Posted by DaveWM (Post 3117782)
I have a 21CYP22 that I have been hanging on to in hopes of getting it rebuilt, it has an open filament on one gun. May have a 21FJP22 somewhere around here that is VERY weak.

only problem is distance, Orlando.

Either would work for my purpose, but I can't guarantee success and I don't want to destroy someones treasure. I have two good delta guns so I can at least make two attempts if necessary.

Even Scotty wouldn't guarantee results.

The ideal CRT would have a problem like a broken neck where the owner wouldn't care what happens to it.

Username1 10-23-2014 11:15 AM

Quote:

Originally Posted by jeyurkon (Post 3117811)
A small bakelite set was shipped to me and arrived in small pieces, through FedEX. Then I won an auction for a 12LP4 and it was shipped to me in a similarly old box, but marked "Glass, Implosion Hazard" and the FedEX guys showed up in a U-Haul with two of them carefully carrying it from the truck.

I'm surprised they didn't charge the shipper a Hazardous Materials fee because of the label.


Yes, I could build a box, but not having such a CRT in hand to fit it would make it difficult for me to do it at my end.

A good shipping experience does seem to be a shot in the dark....

.

Bill R 10-23-2014 07:11 PM

I have one that was necked. Problem is it is still in the set and I don't know when I will get to take it out.

Username1 10-23-2014 07:35 PM

Quote:

Originally Posted by Bill R (Post 3117845)
I have one that was necked. Problem is it is still in the set and I don't know when I will get to take it out.

I think being able to make a good usable tube out of one that was broken
would be a special thing..... :)

.


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