Re-gluing picture tube bases?

[RetroHacker]

I know this is one of those topics that has probably been discussed before, and it seems so obvious - just squirt some glue in there. But I've also heard, from some of the radio guys, that super glue can sometimes cause the glass to crack.

So, I figured I'd ask for the consensus here. I have several sets, including this Zenith that I'm tinkering with at the moment, where the glue holding the picture tube base to the tube has dried out, leaving the base loose - something that risks breaking the tiny wires that go into the glass itself. This same thing happens to octal/large pin base tubes, and I have several older tubes that are loose as well. I also remember accidentally ripping a (very stuck) 5Y3 rectifier apart, leaving the base firmly lodged in the socket, and the glass detached.

What's the best method of re-gluing these? Super glue seems the obvious, but I have heard that super glue shrinks as it dries - and can break the glass. Along with horror stories of freshly glued then broken '01A tubes.

So, suggestions?

-Ian

[Old1625]

I'd try GE clear silicone sealant meself, although I've used epoxy in the past with success. Make sure you have devised a way to temporarily clamp or secure the tube base to keep it pressed against the end of the neck. The silicone will take a day or so to cure enough to make a secure repair. Before you do any of it make ding-dang sure that indeed one of those fragile leads hasn't broken.

Super glue is really only suitable for some plastics and skin.

[dreyfoos]

I understand that the glue used for bases in olden times was an alcohol solvent "bakelite glue." Since that formula seemed to hold up pretty well - perhaps something short of fifty years - I'd like to try it myself but haven't yet found a source.

Another suggestion that I heard about once upon a time was clear fingernail polish diluted to 50% with acetone. I used it on a CRT many years ago but I can't give you a status report because that tube is no longer in my posession. It was a cheap and easy method with the diluted polish nicely filling the glass/bakelite interface. And, a little polish remover or straight acetone will dissolve it - should one need to do some resoldering.

Perhaps we'll learn more about what Scotty uses when we attend the Early Television Convention in May where the play by play of a CRT Rebuild by Hawkeye is scheduled to be shown.

I too would like to hear about it if anyone's found the perfect solution to this situation which we all eventually have to deal with.

Roger

[fsjonsey]

I superglued the loose base of my 17avp4 about two months ago, and it's been fine ever since. I've also fixed loose plate caps that way for years without an issue.

[bgadow]

Someone once mentioned using furnace cement, which might not be far from what the factory used.

[disco]

I use a 24 hour cure epoxy. I would stay away from silicone unless it was approved for electrical use (GE has an approved one). Many silicone adheasive sealants emit a gas when curring which may cause corosion.

[dreyfoos]

(I tacked the following onto a thread in the other forum and I think it's worth adding to this thread. If nothing else, this technique is prettier than five wraps of electrical tape and sturdier than five wraps of masking tape.)

For me, the need was to tighten up the old 3,7,10 and 12-inch CRT bases.

I’ve never been comfortable with using a “crazy glue” because it seems a bit irreversible in a situation where one might want to unglue it for one reason or another. Others have mentioned possible stress to the glass. Since they’re not making these tubes anymore – or the glass bottles, etc. – and with the rebuilding process having a questionable future – I don’t want to do anything that’s going to subtract by even one from the existing stock.

Here’s what I’ve done and I kind of like it. I use a single wrap of 2” transparent packaging tape. Done neatly, it’s almost invisible and – it’s reversible. It yields a very tight result with no likely stress to the glass. This might be better than the acetone-thinned nail polish that I have also used as a glue. The tape stabilizes the joint with a technique that is not hidden – what you see is what you get. (It would be even neater if the tape had a heat-shrink property to make the Bakelite-glass joint a bit tidier.)

But how long will the tape hold up under the heat emanating from the CRT heater or from the temperature environment of the cabinet? Ask me ten years from now. But any sign of failure should be obvious – none of the surprises you may get with a glue. Try it. You might like it.

Roger

[wa2ise]

Originally Posted by dreyfoos

Here’s what I’ve done and I kind of like it. I use a single wrap of 2” transparent packaging tape. Done neatly, it’s almost invisible and – it’s reversible. It yields a very tight result with no likely stress to the glass.

Roger

I've done this too. Works well, and no worries about cracking the glass. Just be sure to clean the dust and dirt off the glass and socket first...

[Josef]

Hi!
Sounds stupid but it works and looks really well for years: I use wood glue to fix loosen tube bases
Greetings Josef

[cdmarion]

Originally Posted by dreyfoos

(It would be even neater if the tape had a heat-shrink property to make the Bakelite-glass joint a bit tidier.)
Roger

This might be a dumb question but what about heat shrink tubing? I'm not sure but I bet you can get it in the size needed. Just a thought.