Replacing tube bases

[Gibsonman63]

I was swapping tubes during a recent gig and broke the key off of a NOS EL34. Otherwise, it is a good tube. Is it possible to change the plastic base out by melting and sucking the solder out of the pins?

[Structo]

What I do is super glue the pin back on being careful to orient it correctly and match up the break.

You can buy new bases that slip over the existing pins, you just need to trim the guide pin flush before sliding it on.
Which could be dicey because the little glass nipple that they seal the vacuum with is usually right there.

AES sells these adapters to fix it. 4 @ $10

http://www.tubesandmore.com/scripts/fox ... m=P-STKY-1

[Phil_S]

Only half joking here....if you have a dentist friend, he's got all the things needed to fix it. In addition, dentists are extraordinarily good with the hand piece and will understand about not nicking the nipple. The thing is, how many of us have a dentist friend? Next best is a machinist who owns an old dental hand piece -- I'm talking about an old timer who actually knows how to use hand tools, not some young 'un who specialized in CNC operations. Third option is use of a Dremel tool to prep it for repair - are you really that good with a Dremel?

IMO, your best bet is probably the part from AES. Try the super glue and see if you get lucky. Super glue trick: after you glue it (and be very careful not to apply excess glue as that keeps it from making a strong bond) breathe on it -- it is the humidity that will help it cure well. Avoid quick setting epoxy -- messy and it won't stand up to the heat, and don't ask me how I know this either.

While it is theoretically possible to melt the solder to remove and replace the base, your chances of getting it done well if you have never done it before probably aren't that good. Not worth trying when you consider the price of the tube.

[Cliff Schecht]

I have done it before and agree that it's hella tricky to get right. It's nice when you're starting from scratch because you can make the leads actually extend out past the socket pins, solder them and cut them flush. When you're starting with pre-cut leads already, it's going to be tricky to get the leads from the tube cleaned, straightened and securely inserted/soldered into the pins. Then there's cleaning the excess solder off of the pins so the now fatter pins don't ruin your sockets..

FWIW I break guide pins off waay too often and still use the tubes with no issues. I've even put tubes incorrectly in the socket and didn't hard the tubes, but getting too far off (i.e. putting HV on the heater) will ruin the tube. It's not that hard to figure out what pins are what to get the orientation right without the guide pin though. What I usually do after breaking a guide pin is put a mark that goes from the tube base to the chassis. When you're putting the tube back in just line up the mark and all is happy..

[Gibsonman63]

It's probably not a bad idea to mark the chassis with the orientation of the key even for tubes with the key still intact.

[Kazooman]

It's probably not a bad idea to mark the chassis with the orientation of the key even for tubes with the key still intact.

I agree with that. I pulled the four power tubes from my Dual Showman Reverb head for safe keeping while I did some work inside the chassis. When I replaced them all of the tubes slid in with no effort but I noticed that the logo on one of the tubes was facing the opposite way from the others. Sure enough, even though the guide key was intact there was enough clearance to allow inserting the tube incorrectly. I caught it in time and was probably lucky that I didn't let the magic smoke out.

[briane]

yeah, just mark it with a sharpy, then look when you insert the tube in the socket. mark the socket too. No reason to replace it aside from something to burn up a bit more of your waking hours.

Do it all the time. really no use to go through all that replacing the base stuff, when you cant even see it.

Still sounds the same.

[ampgeek]

Ditto! Many broken pin'd tubes marked with the sharpie and used for many, many hours with no ill effects.

Dave O.

[Andy Le Blanc]

Ive been poor boy long time

you can unsolder remove and replace tube bases but its time consuming

is the tube worth the time? some fantastic rare NOS deity or uber$$$ hand blown thing with rare element plate?

the key usually covers the evacuation stem, dont snap that off...

[KindaFuzzy]

I use gorilla glue, which is foaming type superglue. Just put a dab or two on the broken tab, push it back on gently, then barely insert the tube into a spare tube socket (just enough to line up the key) and turn it upside down to set overnight so the glue doesn't get on the socket. Scrape off the excess glue that foams out of the crack, and it's good as new.

Gorilla glue works wonders for loose bases too, just poke a bit around the gap between the glass and socket, wipe off excess, and let it set.