Picked this up from the A.R.F. Site.

Amongst other things they claim to be able to rebuild the 15GP22.

Anyone know about this place? I wouldn't mind having a 3KP4 rebuilt.

http://www.wmicronics.com/rebuilttubes.htm

Eric:

That can not be correct. Pete Deksnis has been involved in a 15GP22 rebuilding project for the last several years and they are just finding a way that might work. The rebuilding progress can be followed on his site. I am sure that if some company was already doing that he would have known. I can't wait until someone does find a way!

Steve

Ummm...why do you s'pose it would be listed along with the two early 21" round color tubes among "black & white picture tubes" they claim to rebuild? At first glance, less than credible to say the least.

No way, I'm afraid at this time. There have been many attempts to rebuild 15GP22s, and all have been unsuccessful. As was explained to me several years ago by Gino at MetroColor, the metal flange on the 15G will separate from the bell of the tube as soon as they try to heat it. They tried, with donor 15Gs from Ed Reitan, Gary Miller, and myself. And back in the late 80s, Gary Hough and I tried an experimental rebuild with Dunbar. We couldn't get the 15G gun, but we had two tubes that still had filament continuity re-evacuated. They lasted about a month. The best explanation of "why not?" came from the guys at MetroColor, who have been there since the 50s, and held government contracts and met all ISO guidelines. In other words, they know their tubes. To rebuild the tube, the oven will have to be modified to heat at a precise rate and at a precise temp. There are also many other problems.

Bottom line, be skeptical of anyone who claims they can do it. UNLESS it is one of the women who worked on the original assembly line for the 15GP22, LOL...

Charles

i call bs.
and the big problem with these tubes breaking in the oven is likely due to the complex mask parts and their different rated of expansion.
the mg seal is usually where they leak so no surprise they fail upon heating.

Here's a snippet from an article in the Cleveland Plain Dealer on the 50th anniversary of the CT-100. It quotes Steve McVoy discussing the flange/baking-temperature issue associated with the ongoing 15GP22 rebuild effort.

When the picture tubes were manufactured, air was removed at room temperature by a vacuum machine. The picture tube then was heated in a 700-degree oven designed to excite the remaining air molecules so that as many as possible could be pulled out with the vacuum machine.

With time, the adhesive fails and air leaks through the seam. Restorers are experimenting with a new adhesive that has potential to keep air out for a long time, but the adhesive degrades at 500 degrees. Putting it in a 700-degree oven would not work.

"Right now, we don't know why 700 degrees is the magic number," McVoy said. "Was that the perfect temperature to remove all the air, or will something less than 500 degrees be enough?

"If it works, then we could have lots of tubes," he said. "I have four tubes and six sets that could use them." In addition to the RCA CT-100 and Model 5 prototype, several other brands of TVs of that era used the 15-inch color picture tube.

And another from the CT-100 news & noticespage of my site.

09-05-2005...on the 15GP22 rebuild front, a new, custom-made cam that controls the slew rate of the baking temperature has been ordered. After a few more hurdles (probably most of them as yet unknown), the rebuild team will attempt an engineering evaluation run using a damaged 15GP22 before a bona fide attempt is made to bring a rebuildable tube back to life.

...but we had two tubes that still had filament continuity re-evacuated. They lasted about a month. CharlesSimply put, a month is plenty of time to slop on a bead of sealant and dry it. If the tube survives baking for that long without the custom slue rate, old 15GP22's may soon be looking a lot brighter!

Wonder how they made th' damthings in the first place ? You mean back in prehistoric 19-fackin'-54 they did somethin' we can't do today, w/all our glorious tecknologically & such ?!? Of course, maybe they were a-feared of pissing off David Sarnoff...I hear he didn't exactly suffer fools gladly....-Sandy G.

If RCA originally designed these tubes, you would think there would be archives somewhere of the tube designs and how to manufacture them.

I would think it would be cheaper to manufacture brand new tubes than to break so many in existance trying to find a way to put a new phosphers and gun assembly in an old shell...

When GE bought them the archives were trashed! At least this is I heard in the past. RCA was then bought by Thompson and now by a Chinese company.
I would say that only the name survives.


polaraman

Makes me wonder if a new all-glass crt based on the later 21" tubes would be at all pracitical. It would be terribly expensive & I think that would kill it. Probably one of those things that would cost $10,000 per unit to cover the setup costs. And then it wouldn't be original.

The discussion of the adhesive is interesting. There are some amazing epoxies being made but I don't know how they work as far as heat. This may be a silly question, but I wonder if modern plastics have advanced to the point that a PLASTIC crt could be made? Thats kinda hard to imagine, I know. If it could somehow be done that would do quite a lot to reducing setup costs. That would have to be some tough plastic, though, wouldn't it?

Has anyone (with a little bit of CRT knowledge) thought to call Western Micronics and inquire about the 15gp22 rebuild process? Hell... it couldn't hurt to ask... and it would shed some light on whether or not these yahoos got all of their marbles!

There is always the possiblity (although unlikely) that they might actually have an "all-wise all-knowing big giant head" with the secret to this tube. :yes:

Some time ago I tried to contact them. Their phone had been disconnecteed.

Some time ago I tried to contact them. Their phone had been disconnecteed.

Apparently, this would not be a good sign! :D :no:

So why can't they bake the tube with the old, less-than-ideal sealant that can take the 700 degrees with no problem, then seal THAT seal over with the stuff that will not eventually leak?

Ed (AK user Colortel) told me about 25 years ago in this quest that a "frit" (unsure spelling???) was a piece of special glass that could be laid around the circumference of the tube at the seal that would transmutate into the glass and metal with heat during rebuilding.

Ed, if you read this, maybe you could refresh my memory, enlighten us and elaborate on that? I had kind of forgotten the conversation...

Charles

Charles,

Glass frit (you spelled it correctly) is essentially an extremely fine ground glass that flows into the microstructure of any adjacent surface (metal or glass). The frit is usually a lower temperature glass that has the ability to flow so that coalescence occurs during heating and bonds chemically to the adjacent surfaces. Temperatures as high as 500 degF (371 degC) not only helps the frit to flow but allows for rapid outgassing of the tube (mainly drive off water vapor - which sticks like hell to everything!). During manufacture high temperatures also help to anneal the glass structure. However, it could warp or buckle internal metal parts. As I recall, excess sealant exists during manufacture, so that during high temperature baking the sealant does not all pump out of the joint. However, reheating an old 15GP22 to extremely high temps would not be necessary since the original structure is already outgassed and frit seal created. If only the electron gun is replaced then outgassing may be accomplished at a lower temp, 392 degF (200 degC), within the limits even of any externally applied sealants, e.g. Varian 'Torr Seal'. The trick is to pump the tube for a long time!

'73
Tom Ryan

Did RCA or anybody else rebuild the 15GP22 back in the 50's or 60's? I think we are also reaching the day when even 21FJP22 and 21FBP22's and other delta tubes will not be able to be rebuilt. But there are a lot more of them around so it will be a long long time before they rare and they don't seem to have the vacume loss problem as the 15G does. The way things are going in the CRT field there is a small window left for the rebuild to happen or the sad fact is there won't much of a chance in a few years. I hope people are able to rebuild some of the tubes before the art is gone.
Steve

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Has anyone (with a little bit of CRT knowledge) thought to call Western Micronics and inquire about the 15gp22 rebuild process? Hell... it couldn't hurt to ask... and it would shed some light on whether or not these yahoos got all of their marbles!

There is always the possiblity (although unlikely) that they might actually have an "all-wise all-knowing big giant head" with the secret to this tube. :yes:

I e-mailed these folks after reading this thread. No reply yet, but the disconnected phone probably tells the story.

-Steve D.

I would think that bad 15GP22's in the 50's and 60's did not get rebuilt...since those sets were fairly rare there probably was enough new replacement tubes in RCA's stock to cover the need for replacements.

I would think that bad 15GP22's in the 50's and 60's did not get rebuilt...since those sets were fairly rare there probably was enough new replacement tubes in RCA's stock to cover the need for replacements.

Plus the 21 inchers came out very soon after the 15s were introduced so by the time they needed rebuilt, it was probably a pretty good proposition for a customer to just dump the set and buy a lower priced brand new set with a MUCH bigger screen to boot.

What would a skid (10 or so) of 15gp22's NOS and PERFECT, in emissions and seal, be worth? (NO, I do NOT know where one is... sorry!!)

I am guessing, between 30 and 40k?

There may be such a cache of 15GP22's somewhere so it always pays for all of us to check out old TV shops, etc. before it's too late.
Whenever I'm traveling through little towns in Texas and NM and I come across any TV shops I ask if they have any old round tubes.

There may be such a cache of 15GP22's somewhere ....
In case you haven't seen this story:

In the fifties, for the motion picture industry, the Hazeltine Company developed a system for viewing motion picture internegatives as a positive on a tricolor CRT. It is known as a color film analyzer, and the first one used a 15GP22.

The tube-type color film analyzers are now all gone -- the last all-tube survivor was a model made in the late fifties that ultimately used a 21FJP22. It was in India, still running in 1995.

About 1996, a Mexican company traded in an old analyzer that used the 15GP22. It was totally inoperable, but had been used up to around 1975.

The company from whom I got this information had an inventory of six NIB 15GP22's in stock until 1997, when management decided to toss all the tube-based analyzer inventory to make room. So along with all the other spare parts, there are six 15GP22's buried somewhere in a Los Angles landfill.

So yes, chances are good that somewhere there are undiscovered NIB 15G's.

The six spares in a landfill is a dreadful thought, but here is the flipside: Gary Hough (SoCal TV collector who passed away in '89) found two NOS 15GP22s back East. He bought them for a couple dollars, but found great disappointment in the fact that they had lost vacuum still new in the boxes. I had a similar experience with one that was in a working set, then the next time I fired it up it had failed to lost vacuum. The vacuum loss has nothing to do with how much if any time is logged through usage, so NOS is not applicable in the condition of a 15GP22.

I was told by someone that the manufacturing process involved some kind of procedure whereby the tube was cooked in a vacuum chamber without the front lens on it. Then the front lens and mask were assembled to the tube after cooking, still while inside a vacuum chamber. Zenith, not wanting to pay RCA, had to put visible screws in the mask of their 15GP22 clone because they couldn't figure out how to do it the same way RCA did... But the two known Zeniths still have full vacuum (KNOCK ON WOOD!!!) And one of the Zenith 43M20s with that tube survived being slammed repeatedly against a wall in the Northridge Earthquake... Enough to knock all the knobs off and break one of the wheels and still no glass-to-metal seal cracks! I was terrified to pull the back off that set for MONTHS after the quake, as I was convinced the tube had probably been wrecked. Finally I did and What a relief!

I met one of the 15GP22 assemblyline girls about 10 years ago, and she did recall some strange details. I hate to admit that I can't remember her name. She lives (or lived) in Westwood, CA near UCLA. I did a TV repair housecall for her, and the subject came up. I will think hard to see if I can get a clue and try to pull her up on the database. But even if I find her, I think she was at least 80 then. She was a WWII widow who had originally started at RCA during the war and kept the job on due to loss of husband in war, as I recall her telling.

Charles

I met one of the 15GP22 assemblyline girls about 10 years ago, and she did recall some strange details. I hate to admit that I can't remember her name. She lives (or lived) in Westwood, CA near UCLA. CharlesIntriguing, are there details you can share?

Also, there are tales about RCA attempting to manufacture the 15GP22 in Puerto Rica and even Brazil. Did you glean whether the line she worked on was in Lancaster PA or perhaps there in CA?

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Intriguing, are there details you can share?

Also, there are tales about RCA attempting to manufacture the 15GP22 in Puerto Rica and even Brazil. Did you glean whether the line she worked on was in Lancaster PA or perhaps there in CA?

It strikes me that this lady was from Back East. She remembered how they told her how "special" the tricolor tube was to be, and that she had to wear a space suit while working on it. That's about all the detail I can remember of the conversation, but I remember the type of TV it was that I repaired for her. So next time I visit the shop where that call came from, I will check their database to see if I can get her name & number from searching with the TV make and zipcode.

Charles

I thought the whole problem with the 15GP22 was that it didn't use a frit seal. I thought they attached a metal ring to the bell and another to the screen, then welded the two metal pieces together after the screen was coated with phosphor. Could a bead of frit be added around the two metal to glass seals to seal and strenghten the CRT?

Does anyone know how much air it takes to ruin a CRT?

Yes, that problem is characteristic of all vacuum technology, in general. But, the 15PG22 is a bit of an exception because it so happens that there's a lot of iron inside this tube. 15GP22 would have been an outgassing nightmare for RCA during tube manufacture. For a rebuild there should be much less water vapor to pump out - if the tube is not initially up to air and the rebuilder is clean and pre-baked all parts in dry nitrogen gas prior to installation into the old 15GP22. The more residual gas that's removed the less electron scattering occurs from the gun assembly when cathodes reach emission temperature. Less scattering effectively means somewhat lower emission temperatures are required to create a space charge around the cathode.

The real question to ask is:

How much residual gas pressure does it take to ruin a CRT, i.e. make the tube too dim to watch?

Well, it seems to me that the question depends on both electron gun efficiency and ultor voltage field intensity accelerating the electrons towards the phosphor screen. Bright pictures require more energetic electrons, and more of them, with high kinetic energy to produce more photons as a result of slamming into the phosphor dots at high velocity, hence giving us a brighter picture. As pressure inside a 15GP22 rises to 10-6 torr the rate at which residual oxygen molecules inside the tube strikes the phosphor dot plate rises to 3.6 x 10 to the 11th power (molecules per square centimeter). That's a hell of a lot of garbage in the way of the electron stream trying to hit a group of phosphor dots while being scanned at horizontal line rates! As the pressure inside the tube gets higher towards the 10-5 torr range the picture begins to noticeably lose brightness. Above 10-4 torr the picture starts to get really dim. At higher pressure less than 10-3 torr you can expect the tube to arc over inside - especially when the ultor sits above 20KV. Now, the getter should be turning white too! Also, you don't have to be at room air pressure to internally arc the tube. :nono:

Let’s put pressure into perspective: a new two-stage Edwards EM8 rotary pump (pretty common in most labs) after an oil change should reach 10-3 torr after 24 hours of continuous outgassing. To reach lower pressures requires either a diffusion pump or turbo molecular pump on the system to reach up to 10-6 torr to 10-7 torr range or maybe less (if a turbo pump). To get pressures lower takes either ION pumps or cryogenic pumps to reach the 10-9 range. Passive chemi-absorption techniques - hence the use of a 'getter' inside vacuum tubes can get things down to less 10-9 if the tubes seals are really good and keep it there.

I recall one interesting incident as a graduate student; I once cranked the voltage up on an electron detector in a mass spectrometer quite high one day - just to see what would happen. Even at less than 10-9 torr I was able to strip enough electrons off a detector plate once it reached 40KV to create a massive arc inside the vacuum chamber! Ka-Boom!!! The SS chamber didn't implode - just made a heck of a loud crack ...I jumped, probably 5 feet and ducker under a table. Yet, it always amazes me how modern large CRTs can work at 35KV or higher and not cause severe ionization inside a tube over time - pressures must be very low and kept very stable inside these tubes - a definite a challenge for old tubes! ...of yes, I forgot to mention the 40KV supply I used could deliver over 100 milliamps of current ...several orders of magnitude higher than a TV chassis!!!

Tom

I know this is a bit offtopic for this particular forum, but while we're on the subject of rebuilding tubes... I've heard of people that had set up shop for rebuilding black and white tubes in their houses - from what I'd heard, it seemed simple enough, a car battery and some nichrome wire to cut the neck off the tube, replace the gun and reseal the tube, and pump the air back out. But what kind of pressures are required for a black and white tube? And I'm only referring to all-glass tubes here - the metal cone kind would have the same sorts of sealing problems. But just how low does the pressure need to be in order to have a serviceable B&W tube?

Another thing that confused me about tube rebuilds (B&W tube) - did they replace the phosphors or only the gun assembly? I always thought that the phosphors in black and white tubes degraded with use too. Kinda like the screen burn on computer terminals where something would get burned into the tube if left long enough, and occasionally you'd see a really well used terminal with 24 rows of 80 fuzzy little boxes from where the characters lined up. Wouldn't a black and white tube eventually get the same sort of phosphor degredation over the entire tube? Or does the relatively rapidly changing content on television prevent this?

Basically, there's a lot that I don't know about picture tube rebuilds... Any insight?

-Ian

Sylvania rebuilt tubes were classified as "new gun" or "new gun and screen" so I think a lot of rebuilt tubes , B&W and color, were just equipped with new electron guns.

I really have not seen the kind of phosphor burn you get on old computer terminals on many TV crt's, except in sets from college student union lobbies or motel lobbies, etc. where the Weather channel or cable TV info channel played constantly for many years and burned text into the screen.

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With regards to screen burn I've noticed a couple of things. Color CRTs don't seem to burn as "deeply" a mono CRTs. I've seen several mono CRTs that were used for either surveilance monitors or text displays where the burnt image is clearly readable when powered off. When powered on with a full white (or green, etc) raster the burnt areas weren't just dull, they were totally dark. This also happens with the old orange plasma displays used in some computers.

A while back here a load of ex-TAB 21" Orion TVs hit the market. The were used to display race information on teletext pages. When powered off several lines of text were clearly readable and several others visible as indistinct "shadows". When powered on it was only just noticable on a full white raster. Viewing a normal program you couldn't really see them unless you practically had your nose up against the screen looking for them. I sold several and never had any complaints or comebacks. As long as the customers got to see them running they were happy to take them, even after I explained the screen burn to them as showed them what they looked like when switched off. Of course it helped that I was selling them for half the price of a non-burnt set of the same size, and this was before the used TV market crashed. No-one would even ask about them when they were switched off, even when we dropped the price off the last couple of $20 to clear them out (this was back when a used 21" set would easily sell for $100, even without a remote).

I have a couple of Sony Trinitron studio monitors that were pulled from an edit suite. Both have time codes burnt into the bottom of the screen, but I don't really notice it. Otherwise they have beautiful bright sharp pictures with better color and geometry than many of the 1 year old sets that come through here. I like them enough to use them daily, one as a bedroom set and one in the workshop. Lately I've been watching more movies in the workshop than anywhere else (gotta test the DVD players before they go back out :) ).

I remember going to videogame/pinball auctions, and it was kind of fun looking at the old videogames with used color monitors where you could sometimes decipher what game the monitor had been in previously just by looking at the burn-in pattern : )

I haven't seen anywhere near as many burnt in arcade monitors as I would expect to see. Maybe around here the games were changed more often. The CRT rear projection monitors used in some big Sega and Namco cabinets are a different story though.

If RCA originally designed these tubes, you would think there would be archives somewhere of the tube designs and how to manufacture them.

I would think it would be cheaper to manufacture brand new tubes than to break so many in existance trying to find a way to put a new phosphers and gun assembly in an old shell...


Good point. Actually there is an archive of information right under everyone's noses that was published in the proceedings of the IRE Vol. 42. Here it is:

Grimes, M.J, Grimm, A.C., Wilhelm, J.F. (1954). Improvement in the RCA Three-Beam Shadow-Mask Color Kinescope. Proceedings of the Institute of Radio Engineers. New York, N.Y., pp 315-326.

In this article Grimes, Grimm, and Wihelm describe the advances RCA has made in the design of the all glass color kinescope type 15GP22. Over what you ask? The original prototype was not the all glass tube everyone knows and fears can't be rebuilt today. The 15GP22 design originally started life as a modified 16AP4 metal shell. The 16AP4 was a glass-metal tube that found use in b&w sets that first appeared in the late 1940's. RCA simply added a color viewing screen assembly consisting of a shadow mask + phosphor dot plate and then added a tricolor electron gun. However, RCA quickly discovered a bunch of problems inherent to glass metal tubes adopted for color use. The authors interviewed many RCA engineers and assembly line workers to write their research paper. Maybe even the 80+ year old tech that Charles knows was interviewed. :D

The authors disclose a ton of information that led to changes in materials, assembly techniques and tips for factory production. For example, tube evacuation techniques, e.g. placing the mu metal shield outside the tube to reduce outgassing, improving the tension on the shadow mask by increasing heat dissipation 2.5 times to allow for increase beam intensities to produce brighter pictures, and changes to the blue phosphor to help reduce the classic "trailing edge" effect. The authors even reveal the composition of the shadow mask and the dichromating process used to improve thermal radiation and reduce buckling. Lots of other stuff is discussed too.
:tresbon:

But the real kicker for RCA in moving to an all glass tube design was that it couldn't build the glass metal color tubes fast enough. The authors reveal that RCA management wanted a new color tube to role off the assemble line every 2.5 minutes. The 15PG22 did improve upon the modified 16AP4 in three ways: improved tube performance, parts interchangeability, and decrease in tube cost. RCA eventually lost millions on this tube because the demands of mass production were never realized. The tube also had a high mortality rate in the field. Tubes were failing after assembly or losing their vacuum after delivery in new sets or just simply sitting in inventory. So, anyone who has a working 15GP22 tube needs to understand that it is essential to VacSeal seal all vacuum joints on this tube immediately to guard against the possibility of vacuum failure in the future. :nono:

Corning Glass Works originally manufactured the molds that made the face plate section and the cone (funnel) section of the 15GP22. Prior to assembly a metal flange is sealed onto each part separately. This was done by RCA in a refractory oven using similar techniques for b&w tubes. Glass frit is used to bond the metal flange surface to the glass at extremely high temperatures. NOTE: at this point you are only sealing metal to separate glass parts. They are not yet joined together to form a CRT. The second major assembly step was the use of a very complex jig called an assembly lighthouse. The lighthouse was used to set the mechanical position of the phosphor dot plate to the shadow mask. A special jig is also needed to secure the shadow mask to the cone section flange collet assembly at the correct tension. The phosphor dot plate was then attached to a collet assembly on the face plate section. Once the alignment was completed in the lighthouse jig the flanges of the two halves were then heli-arc welded together. :smoke:

From my experience, a tri-color electron gun assembly may be substituted into a 15GP22 as long as it meets one very critical requirement: the electron beams from the gun must focus at the plane of the phosphor dot plate exactly as simulated using the small light source in the alignment lighthouse during manufacture of the original tube. This would first require precise mechanical alignment during a rebuild so that the replacement gun is attached at the correct position, and establishing the correct electron field density to focus the electron beam during operation. :scratch2:

Finally, I would like to share with everyone what the authors had to say about baking the assembled 15GP22 after final assembly. This was especially critical during outgassing and evacuation. The authors pointed out that the manufacturing of b&w tubes used higher temperatures which were found not suitable for manufacturing color tubes. Why? Slow thermal cycling is required to prevent the shadow mask from bucking. The face plate must be also shielded to prevent it from cracking due to non-uniform thermal shock. Most importantly baking temperatures were tipped off at 300 degC. :yes:

See, when you stop and think about it the 15GP22 resulted because RCA engineers failed in making the "old design" 16AP4 glass-metal color tube work cost effectively. Grimes, Grimm, and Wihelm provide a wealth of information in their article about 15GP22 construction and assembly. The article also reveals what later become known as common sense techniques for color tube production: success depends on using moderate temperatures, slow thermal cycling and long tube evaluation time. :thmbsp:

Tom Ryan

<<<I always thought that the phosphors in black and white tubes degraded with use too. >>>

Since back then there were no news channel crawls, logos, videogames etc. it would have been evenly worn as long as the set was working right. I can see if something went wrong like you lost vertical for hours while nobody was tending to the set and it burned a horizontal line into the phosphors. Or the ion trap got messed up and it ended up causing a burn spot in the center.
Otherwise the big % of the cause of dimness in an old tube is probably the gun's fault or because of outgassing. Plus doing the guns is hard enough, I can imagine the pain it might be to remove/replace the phosphors. How was that done anyway? Or did they even do it?

On the side-note of color tubes with burn, you don't _normally_ see modern color computer monitors with burn, until you start working with junked equipment from state offices, hospitals, etc. Server consoles are pretty bad too - I've seen monitors that very clearly show "Windows NT Server" or "Windows 2000 Server", burned sharply into the screen. Once I even saw one with Windows 2000 burn _and_ NT Server burn. They must have upgraded :). Or offices that have their company logo as the desktop wallpaper, those typically get etched into the screen pretty good. You also see login screens burned into the tube quite a lot. Occasionally, you can see the whole desktop, complete with icons and readable text - even the icon headings of "Microsoft Word" are readable. And that little MS word 'toolbar' thing.

Arcade machines, especially the old ones, get burn in attract mode, or just from use. You can always tell a monitor from a Pac-Man or Ms. Pac-Man machine, the maze is clear as day. One time I even saw a TV set in a thrift store with Atari 2600 Pac-Man burn in it.

I guess that under _normal_ use, the phosphors in a TV shouldn't degrade too much, so rebuilding the tube would be only a replacement gun. It seemed like I read somewhere that the really old B&W tubes suffered worse phosphor degredation - until they switched to an aluminized screen or something like that. But the tube rebuilders probably would look very closely at the duds as they came in, and only rebuild the ones that were going to work well when rebuilt. But I am really curious, if they did replace phosphors in the tube at some point - how did they do it? I can just see someone trying to scrub the old phosphor off the tube with a long brush or something, like cleaning out a bottle.

-Ian

<<<It seemed like I read somewhere that the really old B&W tubes suffered worse phosphor degredation - until they switched to an aluminized screen or something like that.>>

Very early tubes didn't trap the ions so would get an ion burn spot eventually, later they added angled guns + ion trap magnets to suck up the ions, then came phosphors coated with very thin film of aluminum which stopped the ions and eliminated need for traps.

Tom, the 15GP22 is different from other guns in two ways: First, it uses high voltage (around 5 kv) focus, and second, it has electrostatic convergence, with an additional element in each gun. There have been a couple of attempts to use 21AXP22 guns in 15G rebuilds, the assumption being that the screen size is so small that convergence would be adequate without dynamic convergence. I've never seen the results, though.

Black and white tube rebuilds were done with new phosphor (more expensive), or re-using the existing phosphor. This is still true today - Clinton Electronics is attempting a rebuild of the prewar 12AP4, a tube that didn't use an ion trap and therefore had ion burns. They remove the old phosphor and re-coat the tube:

http://www.earlytelevision.org/prewar_crt_rebuild.html

True, the 15GP22 uses electrostatic convergence; however, regardless of the method of convergence in any color tube, the outcome is the same - focusing the electron gun on the phosphor plate. Of course, the physical principles and subsequence circuitry is different (15G uses electrostatic fields and the 21AX gun uses magnetic). Say, glad use did mention the use of 21AXP22 guns - it would be cool to find out who tried it and what finally came of it.

On the subject of phosphors, I've had the unpleasant experience of discovering the non-aluminized black & white tube phosphor the easiest to damage if you suddenly break the seal off nipple at the base of the gun. You can blow away a circular patch of phosphor several inches in diameter off the face plate. I recall calculating the velocity of air once as it enters the tube. At the instance the nipple is broken air rushes into the tube at something like up to 300 miles per hour - depending the length of the tube. Air traveling at this speed does a nice job of blowing away the phosphor. Sort of like sand blasting the phosphor off the glass! Of course, aluminized phosphor is strong enough that this doesn't seem to happen. Guess if you're going to go to all that trouble to rebuild a 12AP4 pre-war tube to recoat the phosphor you're basically building a whole new tube. At least it looks authentic on the outside - not sure how safe the integrity of the old glass bottle would be though. Why not take the last step and replace the old glass too!

If there was a way to replace the glass at a reasonable cost, making a whole new tube would be an attractive alternative. However, the cost of building the molds and having the shells produced would be prohibitive, especially with the limited number that are needed.

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How about the Sylvania "new gun and screen" tubes...did they maybe cut off the front part of the tube?

How about the Sylvania "new gun and screen" tubes...did they maybe cut off the front part of the tube?

Aren't almost all color tubes made with two piece shells?

I believe if you look closely you'll see a bonding agent holding the front of the tube to the bell, how else could they build them?

Since Eric opened a can of worms on the 15gp22..LOL..I have a dud 15gp22 in the basement,i also sold my ct-100 last year to a guy in france.(working).
so i called this place that says they can rebuild the 15gp22 and others.
A lady who answered the phone took my name and number down and are suppose to call back,i will let you all know what is what.!:)
terry

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well its been several hrs since i called them.
no return call..so i called them a 2nd time,this time a guy answered and didnt speak very good english at all,as a matter a fact i had to ask him to repeat what he said..finally he said.. "someone will call you back about 5:00-5:30 pm". click
maybe they dreamed they could rebuild the 15GP22?
kinda like i dreamt last night my Male cat had kittens..:)
terry

well its been several hrs since i called them.
no return call..so i called them a 2nd time,this time a guy answered and didnt speak very good english at all,as a matter a fact i had to ask him to repeat what he said..finally he said.. "someone will call you back about 5:00-5:30 pm". click
maybe they dreamed they could rebuild the 15GP22?
kinda like i dreamt last night my Male cat had kittens..:)
terry

If you get a hold of someone (guess you've already figured out not to hold your breath...) and you get a price I think it might be a good idea to find out just what these guys are doing. Why not ask or email them for details. After all, you got a rare tube. Here're a few questions I would ask:

1) Physical damage to the tube face plate - if so then it may not be repairable. Any scratches or chips may cause tube to implode of crack during baking. Then again, it may not. Just all depends on the damage and where. For a sizeable chip of glass out of a corner of the tube may be courting disaster!

2) Is the tube at air/low vacuum/condition of the getter (silver or white)?
If tube is still under vacuum and getter is silvered then:
What is their inspection process?
If tube is at air do they break the seal cut off the old gun assembly?
and then connect the open funnel stub to a vacuum chamber to do a
slow outgas pre-bake at 150 deg C to drive off water vapor?
It's a hell of a lot easier to pull water out of a 2" stub than a 1/4"
evacuation nipple to pressures of at least 10-6 torr!

3) What's their experience rebuilding the 15GP22? References?
4) What's their rebuilding process? In house or RCA?
5) When they break the seal to start the process do they do it vacuum?
6) Once the seal is broken do they back fill the tube with dry N2 gas?
It may be necessary to physically handle the 15GP22 by hand unless
the rebuild chamber can accommodate the tube easily and be kept
under vacuum at all times.
7) How do they alignment of the gun with the phosphor plate?
8) Do they know which gun goes up?
9) Where did they get their replacement gun assembly?
10) Are they capable of rebuilding the electron gun with new filaments?
11) How do they prepare the tube?
12) How do they prepare the replacement gun?
13) What maximum temp do the bake the tube?
There is no need to exceed 300 degC. Maximum tip off temperature used according to RCA research papers described limiting the original manufacturing process to this temp for the 15G. I would suggest not exceeding 200 DegC but, instead, allowing the tube to bake for a day then gradually reduce to room temperature over 7 days.
14) Are they doing anything special to prevent thermal shock to the phosphor plate?
15) Do they thermally cycle the tube? If so, periods and ramp times?
16) Do they do local annealing of the new glass seal on the gun assembly?
17) What is the maximum tip off temperature during baking?
18) Do they helium leak test the face plate to cone (funnel) seal?
A helium leak test of the feed throughs at the gun base after a replacement gun it critical to make sure the replacement seals are good.
19) Are they able to place a 20KV charge to stress test the tube?
The ability to stress test while actively pumping the tube before sealing allows the rebuilder to further outgas the tube. Especially since these tube have been sitting around for 50 years.
20) How long do they evacuate the tube before sealing?

I suspect that attempts to build these tubes in the past have failed not because of the gun replacement parts (...don't rule anything out though!) but because of suspect improper evacuation, outgassing and stress testing before sealing the tube before finally firing the getter. In my mind, there's no reason why a 15GP22 can't be easily rebuilt. However, if the tube rebuilder thinks they can do a regular 'slap and dash' job like on a modern all glass CRT then it ain't going to be so! Success takes time, exceptional vacuum technique and extreme patience, especially with the rebuilder taking their time not baking the tube to the point where seals and/or phosphor plate are damaged.

Anyways, give it shot. Let's see what they say.

Tom

well its obvious they are not going to return calls as they said..
why would a company mislead about something as this?.i bet they dont really even rebuild the antique tubes they say they can do..maybe it was suppose to say "ANTIQUE TUBES NOT REBUILDABLE" ...but they coulda told me on the phone or called back..maybe ill stick my dud 15GP22 that i have no chassis for into the kitchen oven and see what will happen..:)

I don't think they rebuild any tubes. Notice all the other activities they supposedly are involved in.

this is a cut and paste of what they say on their website...below
************************************************** *****
Below is a listing of the types of tubes we rebuild at WMicronics.

Rebuilt Color Picture Tubes
A66EAF51X01 A66EAK00X01 A66EAK22X21 A66EAK51X01
A66EAK71X11 A66EAS01X01 A66ECF25X05 A66JMZ30X01
A66EAK071X11 A66EAK252X11 A66EAK552X11 A66EAS00X01
A66EAS13X01 A66ECF00X01 A66ECF10X05 A66ECF25X01
A66ECF50X12 A66ECF61X71 A66ECY13X01 A66EHJ43X01
A66PNT16X A66ACT07X A68AGD01X A68EAU25X02
A68EGD032X322 A68ESF002X11 A68ESF002X111 A68ESF002X43
A68KVL74X01 A68KZN696X99 A68EAU28X01 A68ESF002X143
A68JUA125X A68KKN96X01

Screen diagonal 28" and 29" with Full square or Full and Flat.


Rebuilt Black & White Picture Tubes
3KP4 5BP4 7DP4 15GP22
21AXP22 21CYP22

These antique tubes are rebuildable,and can be rephospored. Gassy tubes can be rebuilt. Contact us for a quote.

[QUOTE=On the subject of phosphors, I've had the unpleasant experience of discovering the non-aluminized black & white tube phosphor the easiest to damage if you suddenly break the seal off nipple at the base of the gun. You can blow away a circular patch of phosphor several inches in diameter off the face plate.>>>

Probably is a way to do it by putting some flexible filter or device over the nipple so when it is broken, the air has to go thru the filter or something like that to slow down the de-vacuuming of the tube (?) Maybe just a little rubber hose slipped over the nipple with a filter or pinhole plugged into the other end of the hose.

[QUOTE=On the subject of phosphors, I've had the unpleasant experience of discovering the non-aluminized black & white tube phosphor the easiest to damage if you suddenly break the seal off nipple at the base of the gun. You can blow away a circular patch of phosphor several inches in diameter off the face plate.>>>

Probably is a way to do it by putting some flexible filter or device over the nipple so when it is broken, the air has to go thru the filter or something like that to slow down the de-vacuuming of the tube (?) Maybe just a little rubber hose slipped over the nipple with a filter or pinhole plugged into the other end of the hose.

Frenchy, the early non-aluminized tubes were coated with phosphor that were typically atomized or gravimetrically settled onto the face plate via a liquid alcohol suspension. Baking the tube during evacuation removed the volitials and leaves the phoshpor on the face plate. The only practical way to bring these tubes up to air without disturbing the phosphor is using a very slow leak. Specialty equipment used during rebuilding usually places the entire tube in a vacuum before the vacuum in the tube is breached (usually the neck is cut off to replace the gun assembly). Using a filter on the nipple I doubt would work as it takes only the smallest amount of air rushing in at about 300 miles per hour to disturb the phosphor.

Remember there's about 1,400 lbs/ square inch pushing down on a CRT from the outside world. Ya gotta grab onto ur hose and squeeze it real tight to slow'r down!

[QUOTE=Steve D.]I e-mailed these folks after reading this thread. No reply yet, but the disconnected phone probably tells the story.

I received this e-mail reply this morning:


Steve:
I am on the road this week and I will respond around the middle of next week,when I return.

Regards
Ian B.M.Charles CET
Western Micronics CDN.International
RECYCLE! for a cleaner Environment
http://www.wmicronics.com
A caribe company
110 - 112 East North First Street
Seneca SC 29678
1-864-985-1556


Steve D.

[QUOTE=Steve D.]I e-mailed these folks after reading this thread. No reply yet, but the disconnected phone probably tells the story.

I received this e-mail reply this morning:


Steve:
I am on the road this week and I will respond around the middle of next week,when I return.

Regards
Ian B.M.Charles CET
Western Micronics CDN.International
RECYCLE! for a cleaner Environment
http://www.wmicronics.com
A caribe company
110 - 112 East North First Street
Seneca SC 29678
1-864-985-1556


Steve D.


Steve, I also got a similar reply today from Ian Charles. He omits mentioning he'll return! Ha...

-------------------------------------------------------------------------

From: Ian Charles [mailto:caribe@carol.net]
Sent: Tuesday, December 06, 2005 8:21 AM
To: Tom Ryan
Subject: Rebuilding Antique Tubes


Tom:
At present I am on the road and I will respond around the middle of next week.



Ian B.M.Charles CET
Western Micronics CDN.International
RECYCLE! for a cleaner Environment
http://www.wmicronics.com
A caribe company
110 - 112 East North First Street
Seneca SC 29678
1-864-985-1556

--------------------------------------------------------------------------

So, anyone know what's the reference to a caribe company mean? I found the following on yahoo, not sure if this is the one:

Company Profile
Updated: 05-JUL-05


Signal Caribe Inc.

Private Subsidiary, Headquarters Location
St. Just Rd., St. Just PR 00978, United States
(787) 761-2620,
Line of Business: Manufacturing: Manufacture of electronic components.

Add me to the list of those that have a spare 15G dud....

On the side-note of color tubes with burn, you don't _normally_ see modern color computer monitors with burn, until you start working with junked equipment from state offices, hospitals, etc. Server consoles are pretty bad too - I've seen monitors that very clearly show "Windows NT Server" or "Windows 2000 Server", burned sharply into the screen. Once I even saw one with Windows 2000 burn _and_ NT Server burn. They must have upgraded :). Or offices that have their company logo as the desktop wallpaper, those typically get etched into the screen pretty good. You also see login screens burned into the tube quite a lot. Occasionally, you can see the whole desktop, complete with icons and readable text - even the icon headings of "Microsoft Word" are readable. And that little MS word 'toolbar' thing.

Arcade machines, especially the old ones, get burn in attract mode, or just from use. You can always tell a monitor from a Pac-Man or Ms. Pac-Man machine, the maze is clear as day. One time I even saw a TV set in a thrift store with Atari 2600 Pac-Man burn in it.

I guess that under _normal_ use, the phosphors in a TV shouldn't degrade too much, so rebuilding the tube would be only a replacement gun. It seemed like I read somewhere that the really old B&W tubes suffered worse phosphor degredation - until they switched to an aluminized screen or something like that. But the tube rebuilders probably would look very closely at the duds as they came in, and only rebuild the ones that were going to work well when rebuilt. But I am really curious, if they did replace phosphors in the tube at some point - how did they do it? I can just see someone trying to scrub the old phosphor off the tube with a long brush or something, like cleaning out a bottle.

-Ian
this is why rebuilders have to rephosphor mono crt's.
i change out a few of these a week when rebuilding these control heads.

Now THATS burn-in!

Now THATS burn-in!

If the brightness had been turned any higher it would have been a burn THRU!
: )

i e-mailed them this time.. here is a cut and paste..and he never called,my caller id on my phone would have told me so.. and now he says they are closed till jan 2006???

Terry:
I do not know where you get yoiur facts from,I did return your calls,in one instance I left a message and in the orther instances I did not leave any messages,you are no the only person we have call on,on a daily basis, and it is not my fault when I call you are not there,we do rebuild the Tubes but we are closed for the holidys and will reopen the second week of January 2006,we however will be replying to emails every couple of days.
What do you want to find out ?



Regards
Brian Holder
Technical Manager

Damn, we're just a tad touchy, aren't we? What this putzella don't realise is that if he MAKES NICE, there could be a whole bunch of business being sent his way...I'd hazard a guess a reasonable amount of the old-TV fraternity are either members here, or lurkers, & being kinda smart-alecky like that is NOT a good thing...Just my .02 worth..-Sandy G.

Wow... that's some nice English and spelling.

:no:

Don't know if I'd trust very much to this "Technical Manager".

i e-mailed them this time.. here is a cut and paste..and he never called,my caller id on my phone would have told me so.. and now he says they are closed till jan 2006???

Terry:
I do not know where you get yoiur facts from,I did return your calls,in one instance I left a message and in the orther instances I did not leave any messages,you are no the only person we have call on,on a daily basis, and it is not my fault when I call you are not there,we do rebuild the Tubes but we are closed for the holidys and will reopen the second week of January 2006,we however will be replying to emails every couple of days.
What do you want to find out ?



Regards
Brian Holder
Technical Manager


So wiseguy, what exactly did you do to this dude? I wouldn't want to take anything out of context, we all might get the wrong impression; but the references to the number of messages is curious. How many did you leave him? He seems a bit upset about facts. Darn right edgy. The way he tells it, it sounds like you're calling "on a daily basis"? I'd let the litmus test for ESL pass on this guy. Technical managers are not always the best public relations managers - of course some are great at it. Besides, telephone tag has its moments! Say, maybe you could suggest some mutually aggreable time to chat.

BTW, both Steve D. and myself got emails originally from Ian Charles. I plan to give Mr. Charles until the end of this week before pursuing a reply from him. Now, that should be interesting... :scratch2:

Reminds me of an ex-boss I had... He owned the (nameless out of mercy) TV repair shop in (small equestrian section of Northwest Los Angeles County that ends in ___orth)... He once was so upset that I diagnosed a cracked CRT in a Mitsubishi Bigscreen that he ordered me to "SUCK THE AIR OUT AND SILICONE IT BACK TOGETHER" so he could get the repair :screwy: :screwy: :screwy: :screwy:

I wonder if they know eachother?

Charles

I called them 3 x and not everyday,i didnt say anything as i didnt get to speak to anyone,i then left an e-mail asking if the 15GP22 can really be rebuilt and how much and also asked how long..other people have been calling them and e-mailing ..
they emailed me yesterday back.. here is a cut and paste..


Hello.
The tube can be rebuilt,at present I cannot give you a price not until next year as we have just changed Gun Suppliers and will not know the price for a while,until the negotiation with the new supplier is completed ,We will contact you then.



Regards
Brian Holder
1-864-985-1556
1-864-882-6593 Fax



Regards
Brian Holder
Technical Manager

A new gun supplier for the 15GP22? Do they have a time machine?

I'll say what others are probably thinking: these guys don't know anything about a 15GP22 & maybe don't even know if its bw or color. They just assume all old picture tubes are readily rebuildable & why should this one be any different? If they had ever done one before I really think someone on this forum would know about it. If they have never done one before I wouldn't think their luck would be any better than Hawkeye. I would like to find out I'm wrong about all this.

Yeah, I'm beginning to smell a mouse...-Sandy G.

Curious... just how easy is it to find an NOS gun for the 15g? Is it easier to find a gun than the actual tube? Or is it just as difficult? Anyone know of how many guns are accountable now? I'm sure there are some out there, but, it can't be too many. And I'm sure if someone has a gun, it's probably worth more than it's weight in gold!

I visited a CRT rebuilder called Superior Tube in Carteret, NJ about 10 or 12 years ago when I was first trying to get my 12AP4 rebuilt. I knew nothing at the time of the obstacles to having this done. But the guy there was in the business, and more than willing to take on the job, so off I went, with all the various pieces of my tube in hand.

However it seems that the "old guy" whom I never met had recently sold the business to his assistant (or was it his accountant?) and the "new guy" was either naively optimistic or perhaps just desperately trying to make ends meet.

What a strange place it was! I should have gone back and taken some pictures. The "inventory" of dud color tubes was kept mostly outside, face down on the front lawn. I guess that probably worked ok, but it reminded me of some kind of weird Halloween display.

Inside, it was dark and dirty. I remember thinking "how can they work on something as precise as the inside of a picture tube with all of this dirt around?". There were racks and racks full of duds inside, mostly color but also one whole section containing "antique" tubes. He assured me that he should be able to find a 12AP4 in inventory, but of course that wasn't to be. But he urged me to leave my tube with him, in fact he would begin the job NOW. He wanted to cut the neck off right away, that day (maybe to lock me in as a customer?) and then order a new gun assembly. Then a few days and a hundred and fifty bucks later, I'd be on my way with a good-as-new tube!

I looked at the wobbly, ancient lathe he was using to weld the new gun assemblies onto the tubes, and the sooty bunsen burner flame that was used to melt the glass. And the steel mesh safety cages surrounding the evacuation area, all of which were full of broken glass on the floor, several inches deep! And I started to think that maybe this wasn't such a good idea!

I didn't know at the time that there was no way he was going to be able to rebuild my tube (and obviously he didn't either), but I got the heebie-jeebies from the Frankenstein-esque atmosphere of the place. I've never been to any other picture tube rebuilding enterprise, but I really hope that's not how it's actually done! I've also been told that someone was selling some kit or franchise (or snake oil?) decades ago which would allow you to rebuild tubes in your garage. I don't know if that could have been true -- does anybody have any info on that?

So anyway I decided to wait a bit before I committed. I'm glad I did, 'cause when I went back a few months later, the shop was gone.

--Dave

Guns for 15GP22s are impossible to find. Guns for the 21 inch round tubes are still around, but hard to find. Anyone who rebuilds a 15G has to rebuild the existing gun.

If one did find some old, NOS gun assemblies for 15g's or other old tubes, and they had been sitting exposed to air, for all of this time, they would NOT be useable, would they?? After all, I figure that one thing that makes one tube last longer and perform better than the others, is the purity of the cathode material . So, if an old, unused cathode assembly was welded onto a tube, it wouldn't work very well, would it? or am I totally wrong about this?

Here's a link to a graphic on my site of an actual 15GP22 gun that was used years ago in an attempt to rebuild the 15G. We now have new stems as you know, but back then they were not available and so this was someones way of trying to make do. This gun is welded onto a 14AH button, the base for the 21AXP22. No one knows if this approach was ever actually tried, but it seems unlikely. As you can see, this particular guy has been in the air for many years now.

http://home.att.net/~pldexnis/15GP22on21AXP22stem8bitgrey.jpg

What's all the hub-bub? Just go down to Dunbar like I did, and get your 15GP22 rebuilt for $29.50! See the photo?............................................ .................................................. .................................................. .................................................. .................................................. ............ :bs: April Fool in December!

Actually, this Polaroid photo was of the job that Dunbar did for Gary and me on re-evacuating. I mentioned this earlier in the thread, I think (or in another). The result was that the vacuum stayed for about a month, then the neck started getting the dreaded purple glow. Circa 1982.


Charles

Oh, and BTW: The photo is free to be saved & posted elsewhere by anyone....

---

Kaye Halbert, I Pmed You A 2 Personal & Reg. Email But No Response...did You Lose My Address ? G.b. Can You Still Get Picture Tubes Rebuilt In S. Calif. ?

What's all the hub-bub? Just go down to Dunbar like I did, and get your 15GP22 rebuilt for $29.50! See the photo?............................................ .................................................. .................................................. .................................................. .................................................. ............ :bs: April Fool in December!

Actually, this Polaroid photo was of the job that Dunbar did for Gary and me on re-evacuating. I mentioned this earlier in the thread, I think (or in another). The result was that the vacuum stayed for about a month, then the neck started getting the dreaded purple glow. Circa 1982.


Charles

Oh, and BTW: The photo is free to be saved & posted elsewhere by anyone....

Hey Charles, that's a cool pic. Makes me very nervous just looking at it. Not exactly clean room conditions. About that purple glow, did Dunbar apply VacSeal to all joints - including the evac nipple on the stem? A real shame that the tube lost it's vacuum. Say, I'd be interested in knowing how they pumped the tube - if you can remember the details.

They had two in the midwest in Oklahoma city in the 80's now I think they are gone.

I received ths e-mail reply today re:15GP22 rebuild:


Steve:
I will have to get back to you early in 2006,we have just changed Electron Gun supplier and at present I negotiating prices etc. with them so please be patient,at present I have twenty of these 15GP22 CRT,s to rebuild,and as soon as negotiating is completed I will let you know.
Regards
Brian holder Technical Director
Western Micronics CDN.International
RECYCLE! for a cleaner Environment
http://www.wmicronics.com
A caribe company
110 - 112 East North First Street
Seneca SC 29678
1-864-985-1556


Very strange stuff indeed.
-Steve D.

20 of th' bleedin' things ?!? Okay....-a slightly skeptical Sandy G.

If anyone was located in the Carolinas, it'd be interesting to stop by the address they list and see what kind of operation they have going... and also to SEE twenty 15G's all at one time!

Maybe by changing gun suppliers, they'll be able to get a better price on 15G guns! :lmao:

Ya know... wouldn't it be funny if it turned out that these people can actually do what they claim they can? :yes:

Steve, I just received the same reply. Interesting that there are 20 15GP22's to rebuild. Wow, where does he get that number? Charles could be right...may be the ghost of Dunbar will rebuild for $29.95; or he could be negotiating with Dr. Who to borrow the TARDIS and visit the old plant in Bloomington (I wish!)

-------------------------------------------

From: Ian Charles [mailto:caribe@carol.net]
Sent: Sunday, December 18, 2005 1:52 PM
To: Tom Ryan
Subject: Rebuilding Antique Tubes

Tom:
I will have to get back to you early in 2006,we have just changed
Electron Gun supplier and at present I negotiating prices etc. with them so
please be patient,at present I have twenty of these 15GP22 CRT,s to
rebuild,and as soon as negotiating is completed I will let you know.


Regards
Brian holder Technical Director
Western Micronics CDN.International
RECYCLE! for a cleaner Environment
http://www.wmicronics.com
A caribe company
110 - 112 East North First Street
Seneca SC 29678
1-864-985-1556

Twenty to rebuild. Wow. It is amazing that nobody involved with CT-100s has heard about this. There must be a whole other universe of CT-100 collectors we haven't met yet.

Steve McVoy's CT-100 parallel universe theme gives a surreal quality to this whole thread. And Charlie's idea to have someone local check it out seems pretty good. Seneca, S.C. located in the darkest corner of the Twilight Zone. Or, for us Earthlings, west of Greenville near the Georgia border.

Western Micronics, Seneca, South Carolina : Amazon.com Yellow Pages
Address:http://www.amazon.com/gp/yp/B0004G1FCM/103-9025538-6303851?%5Fencoding=UTF8&n=3999141&qid=1134950731


-Steve D.

Anybody else see irony in the fact that this place is at the intersection of Fairplay & First?

How about gold plating ALL parts to the NOS gun assemblies of 15gp22 to refurbish these rare items. Gold is chemically inert, IS a noble metal(won't oxidize or corrode over time being exposed to air), and a great conductor. I remember seeing old computer parts with gold connectors from the 70s/ early 80s surplus before trend of recycling them for gold.

Wouldn't these high quality 15gp22 gun versions have an indefinte shelf life? Research on good plating shop. here's a thought for herculean task- Has anyone thought of finding a custom glass shop to attempt to make these gun assemblies new using correct glass composition if known(ie. Pyrex, etc.) Between a custom machine shop / and glass shop with expertise maybe something made?

At the least,these TVs are worth cost of goldplating guns if sound suitable???

:scratch2:

They have 15gp22 posted on their website!!!

:eek:

They have 15gp22 posted on their website!!!

:eek:

Under black and white tubes to boot :bash:

Imaginary conversation:
"Hey, I don't suppose you could rebuild a 15GP22, could ya?"
"What was that number again?"
"15GP22, an early RCA color tube
"Yeah, sure, a 15" color shouldn't be any problem. But are you sure its worth fooling with an older model?"
"Heck, yeah. If you can rebuild this one I bet I could get you 20 more to rebuild!"
"Bring them on! I'll place the order for those guns..."
****
"Hey, Charlie, just talked to a fella who thinks he can get us a whole bunch of rebuilds on some old 15" color tubes. I think they must be for the CTC-22, remember those?"

...let’s not forget, we already have manufactured 15GP22 stems, rebuilt 15GP22 guns, and developed a process to attach the stem/gun assembly to 15GP22 neck glass. It’s taken six years to reach this stage. So far, this recycler guy has put up nothing but words.

Do we have any Picture tube rebuilders at all anymore ? ....

I received ths e-mail reply today re:15GP22 rebuild:


Steve:
I will have to get back to you early in 2006,we have just changed Electron Gun supplier and at present I negotiating prices etc. with them so please be patient,at present I have twenty of these 15GP22 CRT,s to rebuild,and as soon as negotiating is completed I will let you know.
Regards
Brian holder Technical Director
Western Micronics CDN.International
RECYCLE! for a cleaner Environment
http://www.wmicronics.com
A caribe company
110 - 112 East North First Street
Seneca SC 29678
1-864-985-1556


Very strange stuff indeed.
-Steve D.

Anybody want to buy the Interstate 80 Highway??? I'm selling it! :D

Charles

There is an ebay auction for a 15GP22 that has gone to air and another one for the CT-100 Speaker Grille.

CT-100 Gone to Air CRT
http://cgi.ebay.com/RCA-CT-100-Picture-Tube-15GP22_W0QQitemZ6265403914QQcategoryZ3638QQrdZ1QQc mdZViewItem

CT-100 Speaker Grille
http://cgi.ebay.com/RCA-CT-100-Speaker-Grille-Complete_W0QQitemZ6265405049QQcategoryZ3638QQrdZ1Q QcmdZViewItem

Stlouisian

Both of which are mine.....I listed them this afternoon since it doesn't seem I'll be getting my cabinet back :(

I'll end up listing all of the parts eventually.

Both of which are mine.....I listed them this afternoon since it doesn't seem I'll be getting my cabinet back :(

I'll end up listing all of the parts eventually.

Tim,

I guess this is the official end of the line for your CT-100 cabinet. Everytime I'm reminded of your situation, I get angry all over again. I hope with this auction you can salvage something out of this.

Best,
-Steve D.

I know what it's like to be left with bits & pieces of what WAS a complete CT-100...

Charles

The police can't find this guy, and he's had the cabinet almost two years. All I can do is lick my wounds, and be thankful that I have one CT-100 that's complete.

I just wish you'd sent the cabinet to me...I have a VERY GOOD furniture refinisher buddy who's very reasonable, & understands about old TVs & radio cabinets..Sure, it woulda been a PITA getting it down here & all, but I KNOW you'd gotten it back-as nice as the day it left the factory...-Sandy G.

I know what it's like to be left with bits & pieces of what WAS a complete CT-100...

What happened there Charles? It's hard to tell what exactly that is from the pictures - was that a house fire? I'm sure there's a sad story behind that one.

-Ian

What happened there Charles? It's hard to tell what exactly that is from the pictures - was that a house fire? I'm sure there's a sad story behind that one.

-Ian

Yes; that was in 1988... The CT-100 was in the room upstairs on the left in the fire picture. It had been recapped and was working. But the miracle of that fire (besides nobody being killed out of the 5 that were in the house), was that the room in the back downstairs where 90% of my TVs were was UNDAMAGED. The only sets lost were the CT-100, a Philco 7" bakelite. Sets that were damaged but salvagable were a Kaye-Halbert Normandy, a DuMont Royal Sovereign 30", and a Scott projection tabletop set.

Charles

Curious... has anyone made any progress trying to follow up on this dude claiming to rebuild 15G's? Wasn't he supposed to be back at work after the holidays?

Don't worry, he'll get back to one of us as soon as the cows come home :thmbsp:

Charles

Hi Kaye Halbert....when You can Email or PM me on a time I could give You a Quick call.....G.B. P.S. If You want to use the Picture of the 27 inch Kaye Halbert go ahead. We may have someone come up with one...

Curious... has anyone made any progress trying to follow up on this dude claiming to rebuild 15G's? Wasn't he supposed to be back at work after the holidays?

I mentioned this a while back in a PM, but I'd like to share what I recently found with all the other 15G-heads here. While searching Google, I pulled up a thread on a TV-service page (dated 4-22-05) and found one of the aforementioned gentlemen trolling for CRT rebuild gear. :rolleyes:

http://forum.eserviceinfo.com/archives/99999932.html

Here's the url of the actual thread... http://forum.eserviceinfo.com/viewtopic.php?t=4002

Apparently, he didn't get any bites on his hook. It would still be interesting to find out what this guy has going on... if he even rebuilds tubes at all.

I make small vacuum tubes for a living. I am a production engineer in a glass tube line. We produce about 50,000 tubes per year. Our vacuum requirements far exceed anything ever required for television tube evacuation so I am quite intimately familiar with processes related to tube production and evacuation. I also worked indirectly with Universal Video, a Minneapolis color tube rebuilder, long since extinct.

My comment is, yes, the "frit" material is a glassy material that, in later tubes, long after the 15EGP22, was used to seal the faceplate to the funnel. This is STILL the preferred method for big tubes. Smaller tubes like the 5 inch monochrome tubes can be blow molded in one piece, with neck and tube entry chamfer molded in. But big tubes generally need to have the funnel molded, the neck added, and then the mask installed. Since the mid 1950's, the lighthouse method of patterning the phosphor dots via a light source at the gun position, through the shadow mask, to the photoresist on the face plate. This faceplate was then forever wedded to this funnel. Once the phosphors, and the metallization over the phosphor (aluminum) were depositied, the faceplate was fused to the funnel with the frit. After this process, the gun was installed into the other end in place of the light source.

Then the entire thing was evacuated to somewhere in the range of 1E-7 Torr, baked to temperatures of about 300C or so, induction fire of the gun and getter, and sealed. Then, of course, a run in process was carried out, including activation of the cathode.

Replacing the seal on a 15 EGP22 with frit migh not be a walk in the park, however. The nature of the mating joints where the adhesive or frit went was not very forgiving in terms of texture, area, degree of parallelism and many other "trade secrets".

While the phosphor on these old tubes does deteriorate, I would submit that a simple cathode replacement might make most tubes quite acceptable in performance. There once was a fellow in Pennsylvania who replaced the filament/cathode in 3KP4 tubes for Pilot Candid's. I had one once and it performed beautifully. Of course this was monochrome. He had worked out the details of removing the gun, replacing the filament assembly, adding a new tip-off tabulation to the wafer, resealing the entire assembly to the funnel and the easiest part, evacuation, baking and sealing.

Were this possible with the 15EGP22, I would think you could evacuate it at a temperature that is safe for the bonding adhesive used on the faceplate. Then you could leak test it with a helium mass spectrometer. Any leaks on the faceplate to funnel seal could be sealed indefinitely with Torr Seal, a sealing adhesive made especially for sealing UHV systems to vacuum levels of 2E-10 Torr! Then the tube could be baked on its dedicated vacuum system for a few WEEKS at a temperature well below the safe temperature for the adhesive. Remember, we don't have to make thousands of these - about 20 or so would do. Thus, for a fee, you could pump on one for weeks or more. Remember, the high temperature of bake out is simply a way to speed up the offgassing process. If the tube, once vented, is kept in a clean dry air atmosphere, no in-diffusion of water into the glass will occur. Thus you only need to bake away the water that forms a few monolayers or so on the surface of the glass and gun parts. This will easily take place in a week or so, even at room temperature. Again, the heat only serves to speed up the process. Once the vacuum gauge reads in the range of 1E-8 Torr or so, you can close off the pump valve and watch to see how fast the tube pressure rises to 1E-6 Torr. From this you can calculate how long it would take to reach excess pressure for tube life (rate of rise test). Please use a cryo pump or turbomolecular pump, not a diffusion pump, to evacuate the tube. Diffusion pumps invariably leave oils behind. An Ion Pump is even better but these typically have slow pumping speeds.

Thus I see no real issues for someone good with glasswork to do this task. It will just take some time.

Sorry for the long post but it's not a short process!

Vacuumguy

Vacuumguy, thanks for the fine information. Weeks evacuating each tube! Wow, but if it works...

Only thing that needs updating however is the number of 15GP22's out there waiting to be rebuilt. With well over one-hundred known CT-100's as well as dozens more other-brand survivors, the number of 15G's for rebuild is at least three times 20.

what ever happened to that place that claimed they could rebuild 15gp22 and others? they still have that tube listed on their website as "rebuildable"
they never returned my calls after i questioned them on telling me the guns are on order..
false ads..?

OK--so they can't bake the CRTs.

But my question would be, why can't they seal the glass-metal junction first. Then evacuate at room temperature, then flush with an inert gas to force out the remaining itsy-bitsy left-over air molecules, then seal the stem? Seems there should be some really inert material, that when used, and a few molecules remain inside the CRT, would not affect anything.

Or, how about putting in some chemical that super-absorbs oxygen. Evacuate until most oxygen is gone, then activate the chemical.

Maybe someone will take one up on the space shuttle, and open the neck on a space walk--look mom, no heat required--although those pesky micro-asteroids could do damage.

Damn, if they don't have anything handy, they could visit Roswell and get something to fit the bill. Those aliens must have had color TV in the 1930s!

I think the closest that anyone has come is what Tom Ryan (not TD Ryan) is doing in San Diego. I think he talked about it earlier in this thread.

If there's enough of a market, I wonder if the Russians would take an order and give a try at building new 15GP22s with the old RCA specs? Maybe modified to eliminate the metal ring? They do a great job making fake 2A3s and EL-34s. This is a serious thought; not a joke...

Charles

How did they build the *&#! things back in '53-'54 in the 1st place? Hard to believe they did something back then we can't do today...

The problem we face is that RCA ran as fast as it could from the 15G once the "BIG Color" models went into production. The 15G was the end result of research goals going back to the 1940's, and was simply out-of-date. Once they had made the leap to the 21-inchers, the marketing folks had no reason to dote on the smaller tube, they wanted, no, they HAD to sell the new models. We forget, deep in our intoxicating nostalgic fog, that this was a business risk, and RCA had to work desperately to keep it's dream alive financially. It would be years before color TV sold worth a darn. Our longing for spare 15G's just wasn't anticipated back then, future nostalgia is not factored in to the end-of-life decisions all manufactured goods face. Manufacturing resources were simply shifted to producing the big tubes. At some point, It had no bearing on the bottom line, the materials specific to it were used-up or even discarded, the production line retooled, the documentation archived, only to be tossed at some recent date. I cannot accurately guess when the last 15G was produced new, but I was surprised to find the one I submitted to Pete's site with the 1959 date-code was the only one he'd seen. It is probably a rebuild.

Having said that, one last hurdle is the Grim Reaper. If you were an engineer in your prime, oh, say, age 40-50 in those days, you are now just plain old dead. Much of the knowledge we collector/restorers thirst for went to the grave with those brilliant minds long ago. I personally tried getting archived RCA data from a kid on the phone at GE back in the '90's, and it proved fruitless. With the sale to Thomson, then to the new owners, I don't hold out any hope. But keep looking!

what ever happened to that place that claimed they could rebuild 15gp22 and others? they still have that tube listed on their website as "rebuildable"
they never returned my calls after i questioned them on telling me the guns are on order..
false ads..?

They'll start rebuilding 15Gs as soon as they buy some rebuidling equipemnt, find a building, raise a little capital, and find the expertise to do it. I'm sure they'd be glad to collect a deposit from you to help them out.

I could imagine an all-glass 15" round color tube being built in Russia (or somewhere). It would not satisfy the purists but it would wake up some dormant tv sets. But even then the start-up costs-configuring the equipment to make the envelope, designing the shadow mask, all the engineering needed to put it all together-even in a third world country to cost would be very high.

Sounds like a nightmare to me. They almost certainly would use 'new' phosphors. The new tube would be driven by a CT-100 designed for the 'old' phosphors. So you'd have to modify the matrix to match the 'new' phosphors. Doubt that you'd ever match the '53 NTSC colors. 'course, it'd be better than a universe of dark 1954 15-in. roundies, I guess...

No promises, but I'll launch an effort to find a woman who I met in the early 90s; a 15GP22 assemblyline worker. She was about 70 or so when I talked with her, and she was still 100% sharp on her memories. She lives a block from Colortel (Westwood apartment, not Omaha). I know I have her name & number someplace, but it will take some searching. I recall in our conversation that she was still friends with others who worked with her at the time. But again, this was 15 years ago so she is now more like 85, and same for the friends she spoke of... Let's be hopeful, because I have another lady customer who is now 101 and is still working as manager of a trailer park, and travels all over the world each summer! And she has a rare TV too...

Charles

...

Sounds like a nightmare to me. They almost certainly would use 'new' phosphors. The new tube would be driven by a CT-100 designed for the 'old' phosphors. So you'd have to modify the matrix to match the 'new' phosphors. Doubt that you'd ever match the '53 NTSC colors. 'course, it'd be better than a universe of dark 1954 15-in. roundies, I guess...

You're right about the color. Some early rear-projection TVs went to P1 green because the modern sulfide green saturates at high beam current, giving magenta highlights. However, the modern matrix with P1 green makes flesh tone too sensitive to hue variations. The fix could have been to go back to the NTSC matrix, but usually it was to introduce a rare-earth/P1 or other mixture that matched the sulfide green. If you put a modern green in a CT-100, you will have the opposite effect - greens, yellows, oranges and flesh tones will move closer together and toward red, and the hue variation over this range will be less than nominal. The major tweak to the matrix for sulfide green would be to increase the R-Y drive, but there are related minor tweaks, so all the matrix resistors would require a change.

By the way, modern blue phosphors are also considerably off the mark from the NTSC phosphors (more towards violet, which moves yellows more towards green, since yellow has to be complementary to the blue to make the proper white). This means that modern sets have improved saturation in the magenta region compared to the NTSC gamut.

Such matrix corrections are always approximate due to being in the wrong place in the system for the gamma characteristic of the picture tube. In modern NTSC sets, this results in reds being overly bright (and cyans being dark) when the hue variation is corrected.

All this explains why HDTV colors are more accurate than current NTSC, even though the green area is more restricted than true NTSC - the HD cameras and receivers actually have color characteristics that are matched to each other, producing colors that are the correct saturation, brightness and hue. PAL has had this since they started, because they standardized on the newer phosphors for their primaries.