News: Trouble logging in? Log in from the login page.
December 08, 2019, 07:05:06 PM

Author Topic: Capacitor smokes!  (Read 320 times)

0 Members and 1 Guest are viewing this topic.

Offline Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 11727
Re: Capacitor smokes!
« Reply #15 on: November 10, 2019, 05:34:40 AM »
I'd recommend buying just a single Sovtek to get your amp up and running properly, then think about the JJ 2A3-40.  There's nothing wrong with the JJ 2A3-40, but they are reasonably expensive to put into an amp that isn't working properly, and they don't make any extra power in the Stereomour.

What I would expect with your bad tube is that when you run the amp, the voltage between ground and pins 1 or 4 on the 4 pin socket with the bad tube will either be 0V or just really low, then the other tube will be OK.  Using the dead tube in the amp shouldn't cause any additional damage after your rebuild.  When I run into situations like this, I will take a black marker and draw a little skull on top of the glass so I don't lose track of the dud!
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline davidnow

  • Jr. Member
  • **
  • Posts: 19
Re: Capacitor smokes!
« Reply #16 on: November 11, 2019, 07:05:22 PM »
Thank you very much Paul, that makes much more sense.
All the best
David

Offline Chris65

  • Sr. Member
  • ****
  • Posts: 336
Re: Capacitor smokes!
« Reply #17 on: November 13, 2019, 06:47:11 AM »
For the price of the JJ 2A3-40 you could get genuine NOS tubes if you shop around. Something to consider ;)

Offline davidnow

  • Jr. Member
  • **
  • Posts: 19
Re: Capacitor smokes!
« Reply #18 on: November 23, 2019, 12:24:15 AM »
Rebuilt the Stereomour this morning and checked the voltage, everything seem to be alright...
The voltages of both 2A3 tubes 1 and 4 pins are about 60V so i can't tell which tube has been suffering from the problem.

Actually, voltages are more than 58V, as high as 64V on 24 and 39 posts. Should i do something to reduce to 58V?

I will let the amp warm up and see if nothing happens... fingers crossed!
Best regards
David

Offline Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 11727
Re: Capacitor smokes!
« Reply #19 on: November 23, 2019, 06:23:00 AM »
Should i do something to reduce to 58V?
No, just be sure the voltage at pin 3 on each socket stay very close to 0V.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline davidnow

  • Jr. Member
  • **
  • Posts: 19
Re: Capacitor smokes!
« Reply #20 on: November 23, 2019, 10:04:55 PM »
The voltage at pin 3 are almost 0V. So i plugged the amp and it is now playing music :-)

@Chris65 : i would be very much interested in the NOS 2A3 brand/type you could advice (which are not overpriced).

David