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  #16  
Old 10-26-2011, 10:05 AM
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Tom Albrecht Tom Albrecht is offline
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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.

Last edited by Tom Albrecht; 10-26-2011 at 03:56 PM.
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  #17  
Old 10-26-2011, 01:16 PM
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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.
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  #18  
Old 12-21-2011, 12:43 AM
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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?)
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  #19  
Old 12-21-2011, 08:24 AM
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Originally Posted by ChrisW6ATV View Post
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?

Last edited by stusnyder; 12-21-2011 at 08:25 AM. Reason: spelling
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  #20  
Old 12-21-2011, 08:57 AM
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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.
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  #21  
Old 12-21-2011, 09:14 AM
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The plus side of using the NASA stuff is it can hold up to oven temps.
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  #22  
Old 12-21-2011, 01:44 PM
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The plus side of using the NASA stuff is it can hold up to oven temps.
yes, but is it a good vacuum seal?
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  #23  
Old 12-21-2011, 06:38 PM
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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?
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  #24  
Old 12-21-2011, 10:16 PM
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Sounds like the stuff NASA used was single-part? There are some amazing two-part epoxies out there right now.
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  #25  
Old 12-22-2011, 11:02 AM
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I don't see any reason it would'nt be..
Well, for example, maybe it out-gases, but they don't care about that for tile adhesive.
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  #26  
Old 12-22-2011, 02:31 PM
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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.
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  #27  
Old 12-22-2011, 09:34 PM
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Quote:
Originally Posted by stusnyder View Post
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?
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.
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  #28  
Old 12-24-2011, 08:09 AM
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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.
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  #29  
Old 12-24-2011, 09:05 AM
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Originally Posted by colorfixer View Post
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.
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  #30  
Old 12-24-2011, 01:43 PM
Don Lindsly Don Lindsly is offline
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Originally Posted by Electronic M View Post
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.
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.

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Last edited by Don Lindsly; 12-24-2011 at 01:50 PM.
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