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-   -   any way to fix a end cap on a 807 power tube (http://www.diyaudio.com/forums/tubes-valves/63963-any-way-fix-end-cap-807-power-tube.html)

karma 8th September 2005 09:27 PM

any way to fix a end cap on a 807 power tube
 
any ideas? its the steal cap on top of the tube has come off. the
wire is still on the tube could it be soldered.

thanks.

Zen Mod 8th September 2005 10:02 PM

you must clean that "top pin"with knife or razor,and you can solder it.
use also some sort of glue resistent to temperature ,to fix cap .

karma 9th September 2005 12:22 AM

whats a good glue?

crazzy glue?:D

Zen Mod 9th September 2005 12:41 AM

I'm too far from you to know any commercial brand in Canada,but if I say "liquid metal" or two-component glue with metal particles ,you'll know ;) ; that sort is usually temperature resistant

look at auto part shops

in case that price of glue is more than one 807 , don't dispare-you can always use that glue for something else ;)

Trout 9th September 2005 12:52 AM

Hi,
I have used believe it or not, High quality Cyanoacrylate glue to tighten up bases on several tubes. You can get it in many different viscosities at most really good hobby shops, It works well bonding metal to glass provided its not stressed excessively.

If its a cap that just has a minor wiggle, You should use the fine penetrating formula, Press the cap firmly to the glass, Wick it in and allow it to dry completely. They do sell an accelerator but I don't generally use it as it tends to weaken the bond. Though It cures instantly when used in this fashion.

Temperature is an issue. Though most Cyanoacrylate are not high temperature, I have even used it to bond parts to model aircraft engines and those generally exceed 300 Degrees F.
gene

amperex 9th September 2005 12:57 AM

Some reported they use high-temp silicon to re-glue due to the high heat.

Tom Bavis 9th September 2005 12:59 AM

I use silicone RTV - sticks to glass nicely. I would clean off the solder on the cap, then depress the center with a punch, making a "cup" around the hole. Glue it on, and be sure the wire is poking through. Solder it tomorrow when it's set.

Geek 9th September 2005 01:29 AM

Quote:

Originally posted by choky
I'm too far from you to know any commercial brand in Canada,but if I say "liquid metal" or two-component glue with metal particles ,you'll know ;) ; that sort is usually temperature resistant

look at auto part shops

Confirmed.

LordCo Auto Parts and Pricess Auto (both in Canada) has it. Don't remember the name, but it's about $10.

Gary P 9th September 2005 01:37 AM

I've re-attached the top cap on several of my 1624's (directly heated version of the 807).

Like mentioned below, carefully scrape the oxide from the wire, concentrating on the end where you will be soldering.

For glue I used J-B Weld, an metal loaded epoxy that is rated for tempretures up to 300C. Place a small amount of the epoxy on the glass where the wire comes out the top of the tube and a small amount of the epoxy inside the top cap. Place the top cap over the wire and glass taking care not go get the epoxy on the wire that you have to solder later.

Let the epoxy cure for a day before soldering the wire back to the top cap.

This has worked very well for the tubes I've repaired. 2 of the tubes have many hundred hours of use after the repair and all is good.

Gary

karma 9th September 2005 02:39 AM

ok thanks:D


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