Any updates on RACS rebuilding early CRTs?
 

A comment in another topic reminded me of the RACS project to rebuild more 15GP22 CRTs beyond the first (successful and still-good) one, and I also do not remember if they either already rebuild 21AXP22s or if those are in an experimental stage at the company. Do any of you know the answers to these questions? Also, have prices for rebuilding either of these tube types been made available? Thanks.

http://www.earlytelevision.org/2010_...tion_RACS.html

As far as I know (and Bob will correct me if he has time), him and John have a pallet of 15G's that are being shipped to France for a rebuilding run. I don't know if they have left our shores yet or any specifics, but right now that's the plan. As stated in the above link, the difficulty still lies in the leaks located in the ultor rings. We know RACS can fix leaks with frit, but that will not work to seal a leaking weld. When I last talked to Bob he was throwing around ideas like using an anodizing process to attempt to fill the microscopic pinholes in the ultor ring, but I believe he is still 'at the drawing board' on that one. Sounds like an interesting alternative to the extremely difficult process of an actual weld, which probably would create more leaks than it seals.

Thank you for that link. I had read the original page but had not returned to it for updates.

Hmmm.. I wonder if I could have my 20BP4 included in the shipment if it has not happened yet? I decided against paying freight for just one tube, and have been waiting for an opportunity to combine with other shipments.

The 20BP4, of course, is not a color tube, but it is a unique DuMont early black and white CRT that RACS can rebuild (I have quote in hand). Transportation is the only issue. I can ship within the U.S. by FedEx Ground at very reasonable price; it's the trip to France that is problematic without combined shipping.

If we combine shipping, everybody wins by splitting the high fixed cost.

Call Steve McVoy, I understand they are trying to get many tubes of all types together for shipment in the event that setting up tube rebuilding at ETF is not possible.

I don't have a CRT in this game, but out of curiosity, is there a scheme to return them to the US as a group?

From what I read on the ETF site they seem to have card board cartons for the individual CRTs and a larger crate that will fit the number of 15GP22 containing cartons that they plan to ship, so they will probably have RACS repackage it back into it's original packaging material (provided that none of the packaging gets damaged on the way there) for the return trip.

Because they already have a crate designed to fit the number of cartoned up 15Gs they are planning to send I seriously doubt that they will be able to add Tom Albrecht's 20BP4 into the over seas crate, but I could be wrong.

speaking of which, whatever happened to the ETF rebuilding efforts? it seems like it sorta died with the wind.

My understanding from their site was that they a) ran out of tubes they could risk, and b) are having problems with sealing the previously mentioned ultor ring leaks. It sounds like the electroplating idea might well work- if not they'd need some sort of thin flowable sealant they could gently vacuum in to the leaks and let cure (UV or IR-cure?) to fix the problem.

I too have my hopes up they solve it, it would definitely be a relief to everyone sitting on a leaky tube that they can still get (near) original tubes!

I think he was talking more about rebuilding in general, in which case there is a 'committee' that was set up to deal with the issue. They are looking at locations mostly, and there's also the logistical aspects of it. It has been suggested that tubes be rebuilt and placed for sale, rather than rebuilding tubes sent to ETF. It's all very much up in the air at this point, no pun intended.

A big issue of just picking up random vintage tubes, rebuilding them, and selling is that who knows which tubes will sell and which won't. Also if that came to pass someone who has a rare or uncommon tube that they don't want to send to France would have to sell their tube to the ETF, hope the rebuild works, and hope they can buy it back without someone else getting their hands on it first.

I do have a down to air 17" monochrome rectangualr I salvaged from a junker which I'd like to give them for practice, and to get it out of my garage.:D

The ones being considered are common ones, such as the 10 and 12" tubes, and of course the 21" colors tubes. It's not like they'd be rebuilding anything willy nilly, hoping it would sell. Only parts with a garunteed return are being considered. But again, I'm not the spokesperson so don't take what I say literally.

The 21" Predicta tube would sell, I need two of them myself.

Once upon a time on Scotty's site it was stated that the Predica tube was the most common antique tube he rebuilt over the years.

Probably because they are an iconic set, which usually got run into the ground from use.

No - the reason is because Predicta CRTs had a very short life due to a design flaw. In designing a very compact electron gun to make the neck of the CRT short, they ended up making a CRT with very poor life.

I suspect that Predictas were some of the shortest life TVs ever made, and the only ones that were run into the ground were those that had their CRTs replaced - something most owners would not do - especially on a set that was generally unreliable in other ways.

My own Predicta (a Holiday) has a CRT that I got rebuilt by Metrocolor Engineering in LA in the early 1990s. It was probably the very last CRT they rebuilt. I had it done as they were basically closing their doors. They managed to short the focus grid to something else so I cannot adjust the focus. Fortunately the focus is pretty good in its unadjustable state.

I seem to recall reading on ARF that those sets had something like a 50% in waranty CRT failure rate, and that this essentially put them in such a bad state that the Ford buy out was pretty much an act of mercy.

I figured I would add to this topic rather than continue in the CTC-4 one. This question is for Bob (ohohyodafarted) if he reads this: Bob, since the leaks in the CRT welds can be stopped (briefly) even by grease, has there been any testing of Vac-Seal? Is there a reason that product may have already been ruled out? (I would figure that if heat is the issue, is it reasonable to consider rebuilding the tube then applying the Vac-Seal as soon as it is out of the oven?)

A few years back a friend of mine worked for a transformer company that had NASA contracts. They were sealing transformers for space applications with what my friend said was the same stuff that they used to glue the heat tiles on the shuttle with. He gave me a can of it. Nasty stuff!!! Black in color. I bonded 2 pieces of 1/4 inch plate steel together. After cure I could not get them apart. Basically destroyed the plates trying. Could this "expoxy" could be used in this application??? Unfortunately he has not worked there for a number of years. Maybe someone here has some kind of connection to NASA?

Problem I see with applying any sealant to the rim of an AXP is that most tubes are a pretty tight fit into the plastic bezel, especially after the insulator is wrapped around it. I'd be afraid that the CRT would not physically fit into the bezel anymore after application of any goo, you'd have to be very careful how you did it.

The plus side of using the NASA stuff is it can hold up to oven temps.

yes, but is it a good vacuum seal?

I don't see any reason it would'nt be.. What exactly did they use to bond the glass parts to the metal in the first place?

Sounds like the stuff NASA used was single-part? There are some amazing two-part epoxies out there right now.

Well, for example, maybe it out-gases, but they don't care about that for tile adhesive.

Whatever material you use to attempt to seal a CRT must have three propoerties:
1. It must survive the 600F oven temperatures during processing
2. It must have a thermal coefficient of expansion which matches very closely the glass/metal of the CRT
3. It must be impervious ie vacuum tight over a very long period of time.



It is not easy to find a material which has all three of these properties. The most likely candidates are:
1. Nickel metal plating to seal the leaks
2. Frit glass to seal the leaks

Bob and I have tested a high temperature epoxy with some success, but it has some TCE issues which may make it unsuitable. We continue to work the nickel plating and frit glass options.

If anyone has any other suggestions, Bob and I would be interested in hearing them.

The glass is FUSED to the metal parts. The process heats the metal parts to the temperature needed to melt glass to a soft molten state around 1500C for soda lime glass used in a crt. When both the metal and the glass are up to temperature, the glass will bond to the metal. Special manufacturing process are used that have many gas jets focused on the glass to metal joint while the parts are rotating and being heated by the flames. It is likely that the pre-molded glass components are pre heated to a temperature slightly below the melting point so that there is not a large differential between the temperature of the molten joint and the rest of the glass pre-formed body of the crt. If you do not heat glass in a pretty much uniform manner, you will cause the glass to fracture.

A good example of what can happen if you don't heat glass uniformly is the couple of people who tried to remove cataracts from a 21FJP22 by using infra red heat lamps or a heat gun to heat the face of the crt; and by so doing created an large differential in the temperature between the front of the tube to the back of the tube, and thus causing an implosion. It is a big no-no to heat glass in a non uniform manner. In a crt rebuilding facility, the cataracts are removed by placing the entire tube in an oven and heating the entire tube in a uniform manner to a point where the PVA bonding adhesive becomes soft and then removing the safety glass while the tube is hot. Then the tube is allowed to cool in a uniform manner. When you remove a cataract in this manner, it is a fairly safe process and fairly simple.

If the leaks are pores in the welds, wouldn't a metal with a liquid point of about 600F be in order? Maybe a metal used in solder like tin, lead if the kovar ring would allow it to plate the seam, sealing the holes.

Thought about using tin plate, and I have a friend in the plating business that does tin plating who could do the work. However we decided on nickel, because nickel plating forms a self leveling homogeneous structure that is more likely to seal the leaks. Not all elements plate the same. Unfortunately my friend who does tin, does not do nickel.

The is lots of speculation on Philco's demise. Ford did not do anything as an act of mercy. Rank and file Philco employees knew of the 1961 Ford buyout as early as 1957. By 1961, less than 40% of Philco's revenue came from consumer products. Any reports of Philco's bankruptcy are incorrect. Philco made a profit every year after WW2, some more than others.

No one could live with a 50% SCR, although bubble top failures exceeded historic levels for all other products. The 1960 models were much improved with a much better chassis and CRT design.

HFII had a vision of Ford becoming another GM by adding a full line appliance line to compete with GM Frigidaire. Philco had new appliance plants in Indiana. Ford also wanted a fast way into the booming space industry, in which Philco had some standing.

Philco's '59 and '60 TV lines had a full line of conventional looking products. The bubble tops were a product planner's scheme to differentiate Philco products on the showroom floor. They certainly did that.

More bubble tops ended up in hotel rooms than living rooms.

Don

I feel that the bubble tops were Philco going to back their roots. Back in the golden age of radio Philco as one of their more successful long lived marketing gimicks used to make sets with really bold eye catching Art Deco cabinets. However by the 50's their cabinet styling had become, comparatively, very plain and boring. It is my opinion that they were trying to return to their Pre-TV marketing tactics when they designed the bubble top.

I am curious whether Vac-Seal has been considered, or ruled out already. If it is strictly because of the heat issue, could it not be applied after the CRT has cooled? Specifically, since the weld leaks may have existed since the CRT was manufactured and they did not cause failure for years if not decades the first time, why is there a need for them to be sealed before the rebuild?

I wondered the same thing, but I think it's iffy. The 21AXP22A that I paid Scotty to attempt went to enough air in 3 or 4 days to produce a bright blue glow from a Tesla coil test. Scotty applied vacseal to the neck/bell area just as a guess (he thought the most likely leak point was the metal pinch-off, which was replaced by the new all-glass gun). This is the tube that we did the helium test on at ETF this past spring, and determined that the leak was a "small" one at a tiny ding on the metal-metal weld. I'm now thinking that even small leaks might degrade the vacuum in the time needed to let the tube cool before the vac-seal could be applied and the getter could be fired, but your guess is as good as mine.

This does bring up the point that a tube could have lasted a long time and then fail quickly after rebuild - it appears that the stress of reheating can make a metal-metal leak much worse. I wonder how many more rejects RCA would have had if they went through a second heat cycle.

Wayne,

My gut feeling is that VacSeal may possibly work. But prior to our experiments with the helium leak detector we always thought that the leaks were in the glass/metal jont. Now we realize the leaks are in the weld. So the next logical step is to see if weld leaks can be sealed with VAcSeal and if the product will hold up under the heat of the evacuation oven cycle. Unfortunately there is no oven to test the theory with since Hawkeye has closed it's doors.

Hmmm - I thought there was already some idea that VacSeal couldn't stand up to the oven, but if we're not sure, it should be tried when we can. Any possibility of info from the manufacturer?

Info here says 400 C:

http://www.2spi.com/catalog/vac/vacleak.shtml

not affiliated,
jr

400 C = 752 F so it should be able to survive the 600 F rebuild ovens......

I was pretty sure that VacSeal had a high temp rating. But we need to do real world experiments with an oven to see if sealing the weld leaks and then running the oven cycle will produce a leak free bulb. That needs to be done prior to doing any rebuilding efforts.

I have one possibility that we can still try here in michigan... I will write him an email and see if he can do some experiments for us. It's still a lot better than sending a dud to France for the test.

It is definitely good to know there may be more ways to accomplish the ultimate goal, rebuilding these CRTs with long-term reliability at a reasonable cost.

Hello Gentlemen,

I will piggy back on this popular thread to wish a Very Happy New Year! to all friends and acquaintances reunited by our common interest for vintage televisions and the endeavours to keep their original CRTs still operational in the 21st Century.

To all of you who hope/plan to have a CRT rebuilt in 2012, be assured that RACS is alive, well and kicking. After a very busy Nov/Dec season finishing another big partial order for the French railway, business will restart briskly in January after a well-earned Christmas season rest & factory close.

I will get on the horn with them next week and provide a full update here.

Friends John Folsom Jr, John Y. and Bob G. are once again opening exciting venues on the 15G rebuild project which may also pave the road to solving similar issues with 21 inch roundie color CRTs also using glass to metal interfaces.

The Color Wars documentary project for which we had the pleasure and honor of interviewing many of you at ETF 2011 is well on its way to entire completion and we hope a US TV Channel will be interested at MIP-DOC 2012, the international documentary trade show, Cannes, France, March 2012.

Let me finish this quick update by asking all to spare a moment in memory of friend and former VK member Eckhard Etzold from Germany who died last year one year day to day in this very night of the New Year.

Best Regards

jhalphen
Paris/France