Author Topic: Loose Valves Bases (2018)  (Read 511 times)

Offline Nidri

  • Trade Count: (+48)
  • AVForums Grandmaster
  • *****
  • Posts: 1,354
  • Total likes: 25
  • Do you have change for a paradigm?
Loose Valves Bases (2018)
« on: October 18, 2018, 11:23:47 AM »
I have some very old octal valves with (slightly) loose bases.
They're not expensive per se, but definitely worth repairing imho.

While researching the topic, I only found two old threads:
(https://www.avforums.co.za/index.php/topic,44582.0.html)
(https://www.avforums.co.za/index.php/topic,45580.msg584066.html#msg584066)

Consensus seemed to be that either i)Araldite or ii) Clear Contact Adhesive will do the trick.
(And that superglue is perhaps not the best idea.)

I couldn't source any Araldite but have succesfully used this slow-setting UHU Epoxy before in other applications:
(http://www.uhu.com/fileadmin/extern/hhr/htdocs/en-us/product/detail/productCategoryIndex/2/productIndex/epoxy-ultra-strong)
(https://www.builders.co.za/Fixings-Fasteners-and-Adhesives/Adhesives/Uhu-Epoxy-Ultra-Strong-Tube---Clear-%2820g%29/p/000000000000528772)

Couldn't find any specs, but assuming a good sub for Araldite?

Or should I stick to something basic like this:
(https://www.builders.co.za/Fixings-Fasteners-and-Adhesives/Adhesives/Adhesive-Contact/Pattex-Contact-Adhesive-Transparent-Carded-(50ml)/p/000000000000011053?gclid=EAIaIQobChMI-9vYi9KP3gIVApPtCh0nggVKEAQYBCABEgK3U_D_BwE)

Are there any other/new opinions RE which approach is better?


P.S. Not keen on importing some expensive, proprietary solution to solve this (fairly rare) problem.

Offline marantz123

  • Trade Count: (+1)
  • AVForums Veteran
  • ***
  • Posts: 291
  • Total likes: 5
  • I learnt more from The Internet when it was slower
Re: Loose Valves Bases (2018)
« Reply #1 on: October 18, 2018, 12:06:18 PM »
Would exhaust putty ( gun-gum) be an option ? Its very cheap andnsets rock hard, handles high heat very well.

Offline marantz123

  • Trade Count: (+1)
  • AVForums Veteran
  • ***
  • Posts: 291
  • Total likes: 5
  • I learnt more from The Internet when it was slower
Re: Loose Valves Bases (2018)
« Reply #2 on: October 18, 2018, 12:10:28 PM »
Another thought about exhaust putty....is it conductive at all ? If so, may not be suitable in contact with the contacts/pins in the valve base.

Offline fdlsys

  • Vinylist
  • Trader
  • Trade Count: (+87)
  • *****
  • Posts: 8,141
  • Total likes: 72
  • Do you like life, sweetheart?
Re: Loose Valves Bases (2018)
« Reply #3 on: October 18, 2018, 01:31:06 PM »
Would exhaust putty ( gun-gum) be an option ? Its very cheap andnsets rock hard, handles high heat very well.
2nd that if it's non conductive (easy to test).
The other option would be Pratley Putty - similar properties to gun-gum and I seriously doubt that it would be conductive.

Generally, easy-to-find over the counter clear epoxies are not good at all at elevated temperatures.
Superglue needs a perfectly mated non porous surfaces and is typically not great with metals and even some plastics.
Normal contact glue will perish very quickly at high temperatures.
The four building blocks of the universe are fire, water, gravel and vinyl. Dave Barry
Come back when you’ve lived a little. Miles Davis

Offline charles

Re: Loose Valves Bases (2018)
« Reply #4 on: October 18, 2018, 03:10:00 PM »
From one of my old postings:

"I have always just used clear contact adhesive. Worked for me and I have never had any problems. Guess it is pliable enough to absorb any expansion caused by heat."

I agree with Family_Dog. I use the same adhesive."


Offline handsome

Re: Loose Valves Bases (2018)
« Reply #5 on: October 18, 2018, 03:39:29 PM »
If the bulb is cracked then you lose the vacuum and the valve is useless. If the valve works then the bulb is not cracked.....so do you really need to "repair" it?

Offline JohnnyIC

Re: Loose Valves Bases (2018)
« Reply #6 on: October 18, 2018, 05:35:42 PM »
A while back I had a pair of Quad II amps, two of the kt66 valves had loose bases so I tried acetone after someone suggested it to me(think it was Andre aka Kent) and it actually worked.
Lots of info on the net if you google "loose valve base acetone".

Offline Nidri

  • Trade Count: (+48)
  • AVForums Grandmaster
  • *****
  • Posts: 1,354
  • Total likes: 25
  • Do you have change for a paradigm?
Re: Loose Valves Bases (2018)
« Reply #7 on: October 18, 2018, 06:46:57 PM »
If the bulb is cracked then you lose the vacuum and the valve is useless. If the valve works then the bulb is not cracked.....so do you really need to "repair" it?

That's a fair point.
I suppose I'm just trying to stop the bases from loosening even more.

Thanks all for the input.
I think I'll be able to sort this out now.
n

Offline fredeb

Re: Loose Valves Bases (2018)
« Reply #8 on: October 18, 2018, 09:08:03 PM »
I also wondered about using Gungum - although this may work itself loose again if you pull the valves from the socket by tugging on the glass bulb bit .

I have some KT66's with loose bases - perhaps I should experiment a bit .
...evolution is the gradual development and stratification of progressive series of wholes, stretching from the inorganic beginnings to the highest level of spiritual creation.
Jan Smuts

Offline Nidri

  • Trade Count: (+48)
  • AVForums Grandmaster
  • *****
  • Posts: 1,354
  • Total likes: 25
  • Do you have change for a paradigm?
Re: Loose Valves Bases (2018)
« Reply #9 on: October 19, 2018, 07:03:52 AM »
^^^ Gungum Style   ;D

Offline fredeb

Re: Loose Valves Bases (2018)
« Reply #10 on: October 19, 2018, 02:03:13 PM »
...evolution is the gradual development and stratification of progressive series of wholes, stretching from the inorganic beginnings to the highest level of spiritual creation.
Jan Smuts

Offline Kent Kassler

Re: Loose Valves Bases (2018)
« Reply #11 on: October 20, 2018, 09:12:48 PM »
....just get some acetone down into the seam and it will re-activate the bond....much simpler and works a treat!
Audiophile Sound Sommelier Extraordinaire....aka Manic Depressive Temporary Void Filler Deluxe.

Offline Kent Kassler

Re: Loose Valves Bases (2018)
« Reply #12 on: October 20, 2018, 09:16:22 PM »
A little shifting and pressure immediately after is all that's required.....then leave them be overnight.
Audiophile Sound Sommelier Extraordinaire....aka Manic Depressive Temporary Void Filler Deluxe.