News: Trouble logging in? Log in from the login page.
October 17, 2019, 11:22:57 AM

Author Topic: left channel buzz [resolved]  (Read 495 times)

0 Members and 1 Guest are viewing this topic.

Offline rogerfederer

  • Jr. Member
  • **
  • Posts: 27
left channel buzz [resolved]
« on: May 10, 2019, 04:31:49 AM »
i had not used it for months but had no buzz last time i used it (back then).  now a buzz on the left channel that does not vary with input or output selected.  also, changing volume pot does not change it.  switched tubes and not follow the tube.  not rest of system, which i tested with other preamp (LDR) and dead silent.  i used deoxit on the pots but not fix.

in an attempt to reduce microphonics i have isolated top plate from plinth with mortite caulk; maybe that allows a bit of flex in top plate that could affect solder joint(s)?

troubleshooting suggestions?  am at work but can play with this over the weekend.  many thanks!
« Last Edit: May 12, 2019, 08:15:30 AM by Paul Birkeland »

Online Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 11444
Re: left channel buzz
« Reply #1 on: May 10, 2019, 04:42:04 AM »
I would absolutely suspect a loose solder joint or a loose connection.  It is unlikely to be related to the pots if it's still there with the volume pot turned all the way down. 
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Doc B.

  • Administrator
  • Hero Member
  • *****
  • Posts: 7827
    • Bottlehead
Re: left channel buzz
« Reply #2 on: May 10, 2019, 05:54:30 AM »
Yup, if it sat unused a situation is created where oxidation could build up at the bad solder joint. With normal use the current flow seems to keep this process from accelerating as fast. That's kind of a shaky theory, but my experience seems to indicate it is the case.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline rogerfederer

  • Jr. Member
  • **
  • Posts: 27
Re: left channel buzz
« Reply #3 on: May 10, 2019, 05:55:03 AM »
thanks; will heat up the iron this weekend!

Offline rogerfederer

  • Jr. Member
  • **
  • Posts: 27
Re: left channel buzz
« Reply #4 on: May 12, 2019, 07:30:20 AM »
d'oh!  found bare wire touching the top plate.  bent it and buzz is gone.
thanks as always for the quick advice on this forum!

UPDATE: still getting buzz under some circumstances.  will keep trying different sources.  next will try reflowing some joints.
« Last Edit: May 12, 2019, 03:31:59 PM by rogerfederer »