Loose valve base

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little eddy
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#1 Loose valve base

Post by little eddy »

I have just received an old 5-pin 4V valve but the base is slightly loose with a small gap between base and glass envelope.

Should I just leave it but I am bothered that if I pull/twist on the glass when fitting or removing the valve, I will do some damage?

It looks like I could squeeze some superglue between the top of the base and glass envelope. Is this recommended?
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Greg
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#2

Post by Greg »

Yep, if it was mine I'd drizzle in some super glue or even delicately apply some epoxy resin glue. I've done this several times in the past with valves as you have described to total satisfaction. Some may disagree with me on this, so wait and see their responses.
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little eddy
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#3

Post by little eddy »

Seen on the web some people saying they had been advised or read that you should not use superglue on rectifiers or large power valves but no one actually saying this had happened. Others have said they've use it on small signal triodes.

This valve will have a heater rating of 4VA and anode dissipation of also around 4VA.

If I am to use superglue, guess the trick might not be to use it all the way around but maybe only in one place to minimise risks due to expansion.
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vinylspinner
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#4

Post by vinylspinner »

Hi,

Be aware that some blends of superglue will crack glass, check that the one you intend to use is suitable for this purpose.

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Mike H
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#5

Post by Mike H »

Should never pull or twist on the glass anyway. :D Problee how it got broke originally.

Same prob with top connectors, speshly when clip gets corroded on.

I might try Araldite, which tends to 'creep' under gravity until it sets so should run further in.
 
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little eddy
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#6

Post by little eddy »

Mike H wrote:Should never pull or twist on the glass anyway. :D Problee how it got broke originally.
It is NOS in original Cossor box. I know the seller and sure it would have been checked before despatch, so has only happenned in shipping or just when I've handled it but not tried to insert/extract from a socket yet. That said, it is probably the best part of 70 years old so guess the cement must weaken over time.
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Mike H
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#7

Post by Mike H »

Quite possible it's expired of old age yes.
 
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#8

Post by steve s »

Many of the old vavles will do this, you must be carefull to ensure none of the wires inside touch when you re stick it, check all the pins with meter for shorts after. You should just get a circuit across the heater
Run nail varnish remover round the bass with a fine artists paint brush you will feel it grab as you very slightly twist/ push the base tight, it will be as good as new. It revitalises the original glue, you can split the valves the same way
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little eddy
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#9

Post by little eddy »

steve s wrote:Run nail varnish remover round the bass with a fine artists paint brush you will feel it grab as you very slightly twist/ push the base tight, it will be as good as new. It revitalises the original glue.
What a great tip Steve. Seems to have worked fine.
TD-125/RB250/MC25FL & 'Snail' phono, NAS/SBT with CS4398 DAC, 41MP pre & MoFo Power, still messing with OBs.
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