Repair: Tube Separated from Base

[andrewsrea]

Just sharing a repair tip, for when the glass of an output tube (6V6, 6L6, KT66, EL34, etc) becomes separated from its plastic base. A handful of times I've encountered condition where the tube is still operational but won't be for long as it is being held in place by the fine wires which connect the inside components to the base pins.

Required tools and supplies:
- Jewler's tiny blade screwdriver.
- 3" wide masking tape.
- Paper towels
- Small piece of wax paper
- 3" blue (low-stick) masking tape
- Permatex 'The Right Stuff' 90-minute gasket maker (Walmart, Auto Store, etc.)

1.) Insert a small blade screwdriver between the socket and the tube base and gently pry to remove the tube. Be careful not to move the glass.
2.) Using compressed air, remove dust and dirt from the contact area.
3.) Have some scraps of paper towels ready (this can be messy) and lay out a 3"x3" piece of wax paper for the adhesive compound.
4.) Apply a dab of Permatex 'The Right Stuff' 90-minute cure gasket sealer, onto the wax paper.
5.) Using the jeweler's screwdriver, grab a little gasket goop onto the tip and apply it into the gap between the tube glass and base. Think through each movement, because it is messy. Wipe away excess immediately using a clean paper towel. Spin and repeat until the whole tube base has been treated.
6.) Tear off a 12" piece of the masking tape and wrap the tube end-over-end, compressing the base onto the glass.
7.) Let sit over night before using.

An output tube glass surface can reach 250 degrees F and the gasket maker can handle temperatures up to 650 degrees F. The gasket maker is 'rubbery' and provides the added bonus of some vibration dampening to the glass and internals.

Just did a KT66 which would have cost $126 to replace and $256 to replace with a matched pair. Whew!

[mozz]

I've wicked crazy glue in there for a quick cure, not a lot only a tiny bit. There was actually the recipe for the original stuff online, but the ingredients were for mixing up 100 lbs of the stuff.

When you break a keyway, these work great.
https://www.tubesandmore.com/products/k ... ctal-tubes

[andrewsrea]

I've wicked crazy glue in there for a quick cure, not a lot only a tiny bit. There was actually the recipe for the original stuff online, but the ingredients were for mixing up 100 lbs of the stuff.

When you break a keyway, these work great.
https://www.tubesandmore.com/products/k ... ctal-tubes

I thought about super glues but haven't had luck with them adhering with wild temp fluctuations. I fixed a piece of vinyl rail facia which lasted until the first freeze. This gasket maker is made for zero to 280 degrees daily operation, under hydrostatic pressure. May not look fantastic, but will do the trick.

[artandsoul]

At the current price of power tubes Great idea to patch it and keep it going for cheap! Def sounds like something I would do for sure thanks for the valuable info! I got luckly and bought 4 sets of ehx el34 for my 100w amp for 40.00 for a quad years ago. I cant imagine buying a matched quad of el34 ehx tubes now for 130.00 lol crazy high and only see prices going up!

[andrewsrea]

At the current price of power tubes Great idea to patch it and keep it going for cheap! Def sounds like something I would do for sure thanks for the valuable info! I got luckly and bought 4 sets of ehx el34 for my 100w amp for 40.00 for a quad years ago. I cant imagine buying a matched quad of el34 ehx tubes now for 130.00 lol crazy high and only see prices going up!

Agree.

IMHO, EHX Russia made the best tubes and due to the war, they a re less abundant and way more expensive. Slovakia (JJ) is still cranking them out, but their quality is not wat it was 20 years ago and some of their tube types sound sterile to me. China makes some good tubes and their quality has increased, but they are coming out of their own pandemic lockdowns and are behind no production.

I believe the tubes I am using are Gold Lion KT66, rebranded to Marshall per their specs for the 2000's Jimi Hendrix stack reissue. They have always been expensive (the choice of audiophiles for McIntosh type audio amps) and are now just insane.