[Nick 214]

Hey guys,

I was cleaning my amp (Jolida 202) which means taking out all of the tubes. The small signal tubes (2x 6N1, 2x 6N2) went swell, as did 3/4 JJ EL34s. However, one of the tube's black "base-key" (the middle plastic part with the notch to show orientation in the socket, yeah I made up that term) broke off, in the socket.

Thus, exposing the glass at the bottom. The tube looks otherwise fine, and did not shatter in my face, or anything bad. I put it back in the socket all-well-and-good....

Should it be a-ok for turn-on? Or should I trash the tube? I'll try to get some pics/video up in the next few hours.

Here's a clear shot sourced online:

It's the black plastic piece in the middle of the pins.

Thanks

NK

 

[mulveling]

I've had vintage tubes like that - they work FINE, as long as the glass envelope hasn't been severed and nothing's been knocked loose INSIDE the tube. You'd be able to tell immediately if the former were the case, as the getter flashing would turn from silver/gray/black to chalky white (it reacts when exposed to air). To test for the latter case, just (gently) shake the tube and look/listen.

With the guide pin gone, be careful to get the correct orientation of the pins into the socket. It's a good idea to mark the base of the tube with the appropriate sharpie color, in the guide pin's place.

I once bumped a tube in its socket and broke the guide key off. In that case, however, the halo getter also broke off and rattled around freely within the tube

In THAT case the tube must be trashed, since loose metal IN the tube will cause a short, and likely catastrophic failure.

Barring the above, it probably *should* be ok, for a turn-on, but if you want to be absolutely safe, then you should have a tube re-tested after it's been exposed to any sort of physical trauma like that.

On an unrelated note, I've also heard some not-so-great things about the JJ power tubes' reliability. I've personally had good experiences & sound with the Electro-Harmonix EL34 & 6CA7, which sounded better to me than the JJ/Teslovak EL34LS.

 

[Nick 214]

Quote:

Originally Posted by mulveling /img/forum/go_quote.gif I've had vintage tubes like that - they work FINE, as long as the glass envelope hasn't been severed and nothing's been knocked loose INSIDE the tube. You'd be able to tell immediately if the former were the case, as the getter flashing would turn from silver/gray/black to chalky white (it reacts when exposed to air). To test for the latter case, just (gently) shake the tube and look/listen. With the guide pin gone, be careful to get the correct orientation of the pins into the socket. It's a good idea to mark the base of the tube with the appropriate sharpie color, in the guide pin's place. I once bumped a tube in its socket and broke the guide key off. In that case, however, the halo getter also broke off and rattled around freely within the tube In THAT case the tube must be trashed, since loose metal IN the tube will cause a short, and likely catastrophic failure. Barring the above, it probably *should* be ok, for a turn-on, but if you want to be absolutely safe, then you should have a tube re-tested after it's been exposed to any sort of physical trauma like that.

Oh, good.

Thanks!

NK