variac humming

ask your general tube related questions here

variac humming

Postby nyazzip » Mon Jan 20, 2014 12:41 pm

i have a 10 amp variac (that has maybe a 7 amp fuse in it) that i noticed humming intermittantly this summer when the switch is on, and seems like it might be getting worse. this happens even when there is no load attached to it. it is quite noisy....sounds like 60hz.
is something going wrong...? is it going to burn down the house when i'm gone? or not to worry?
User avatar
nyazzip
KT88
 
Posts: 1073
Joined: Wed Jan 09, 2008 1:24 am

Re: variac humming

Postby azazello » Mon Jan 20, 2014 4:37 pm

If I leave home, I switch off all and 2 time check....
Projects: OTL 6AS7 Gen, Electric, SEs 2A3 RCA, 300B JJ, 6S4S, 4P1L, EL11 Telefunken, 6AS7 RCA, 6S33S, 6S41S, 6S19P, headphone ampl. OTL Loftin White 6AS7 RCA....SE E84L&E80CC Siemens&Tel-n.
User avatar
azazello
KT88
 
Posts: 285
Joined: Tue Nov 10, 2009 8:24 am
Location: Bulgaria - EU

Re: variac humming

Postby DeathRex » Mon Jan 20, 2014 6:56 pm

Swing Low, Sweet Chariot?
At first I wanted to be a ET. Now I are one.
User avatar
DeathRex
KT88
 
Posts: 1014
Joined: Wed Nov 18, 2009 8:13 pm
Location: Cortez, CO

Re: variac humming

Postby Geek » Mon Jan 20, 2014 7:15 pm

Different loads on the line can make a transformer or VARIAC sing. It's due to asymetrical waveforms.

Unless it's getting hot, I'd not worry about it.

But unplugging things while not home is a good idea. I have my entire bench circuit on a switch.

Cheers!
-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
User avatar
Geek
KT88
 
Posts: 3585
Joined: Sun Oct 21, 2007 3:01 am
Location: Chilliwack, British Columbia

Re: variac humming

Postby nyazzip » Mon Jan 20, 2014 8:28 pm

i did recently move, so there is plenty of industry all around me now...i live about 2 miles from Chicago O'Hare airport now. maybe that's why i am hearing things
:/
User avatar
nyazzip
KT88
 
Posts: 1073
Joined: Wed Jan 09, 2008 1:24 am

Re: variac humming

Postby bone » Tue Jan 21, 2014 3:45 am

Carbon dust from the brush contact can partially short adjacent windings. Give it a good clean and then check.
bone
 
Posts: 12
Joined: Thu Oct 07, 2010 8:53 am

Re: variac humming

Postby Geek » Tue Jan 21, 2014 7:13 am

bone wrote:Carbon dust from the brush contact can partially short adjacent windings. Give it a good clean and then check.


An indication of this is if the unit smells. Does it, nyazzip?
-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
User avatar
Geek
KT88
 
Posts: 3585
Joined: Sun Oct 21, 2007 3:01 am
Location: Chilliwack, British Columbia

Re: variac humming

Postby nyazzip » Tue Jan 21, 2014 12:17 pm

bone wrote:
Carbon dust from the brush contact can partially short adjacent windings. Give it a good clean and then check.

An indication of this is if the unit smells. Does it, nyazzip?


no odor or heat, but i did raise a ton of dust in the past 8 months with drywall/spackle and such...maybe i'll clean 'er up a bit
User avatar
nyazzip
KT88
 
Posts: 1073
Joined: Wed Jan 09, 2008 1:24 am


Return to tube 101

Who is online

Users browsing this forum: No registered users and 9 guests

cron