Help! Strong hum from transformer - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 1st December 2007, 01:06 AM   #1
some1x is offline some1x  Canada
diyAudio Member
 
Join Date: Jan 2006
Location: montreal
Default Help! Strong hum from transformer

I have been using a N.E.W A-20.1 amplifier (based on Pass design?) for a while. Today, for no reason, the transformer started to hum very loudly.

I didn't make any modifications to the amp, change any components in my system, move the amplifier, etc. There was no hum yesterday

I opened the top cover to check out the transformer. It is very securely fitted between two metal plates with rubber sheets in between. Don't know what is wrong.

Anyone who can recommend a way to fix or diagnose the problem?
  Reply With Quote
Old 1st December 2007, 01:21 AM   #2
eyoung is offline eyoung  United States
diyAudio Member
 
eyoung's Avatar
 
Join Date: Aug 2007
Location: Sunny SC,USA 15 min south of Charlotte NC
hello all...

a high current draw will cause the transformer to make more mechanical noise ck your bias current each channel make sure you are not geeting ready to have a meltdown..

good luck, Elwood
  Reply With Quote
Old 1st December 2007, 01:22 AM   #3
some1x is offline some1x  Canada
diyAudio Member
 
Join Date: Jan 2006
Location: montreal
Thanks for the fast reply. How do I check bias current? I have a generic DMM somewhere...
  Reply With Quote
Old 1st December 2007, 02:24 AM   #4
eyoung is offline eyoung  United States
diyAudio Member
 
eyoung's Avatar
 
Join Date: Aug 2007
Location: Sunny SC,USA 15 min south of Charlotte NC
allrighty then... howze about a schematic??? to peruse...



Elwood
  Reply With Quote
Old 1st December 2007, 01:25 PM   #5
some1x is offline some1x  Canada
diyAudio Member
 
Join Date: Jan 2006
Location: montreal
I don't have one The problem fixed itself after I reconnected everything on the amplifier. Lucky
  Reply With Quote
Old 2nd December 2007, 01:40 AM   #6
eyoung is offline eyoung  United States
diyAudio Member
 
eyoung's Avatar
 
Join Date: Aug 2007
Location: Sunny SC,USA 15 min south of Charlotte NC
that was easy enough... glad i could be of service, it's what i do best...nothing.

good luck E.
  Reply With Quote
Old 9th December 2007, 04:05 AM   #7
some1x is offline some1x  Canada
diyAudio Member
 
Join Date: Jan 2006
Location: montreal
arrgh! The hum randomly resurfaced. Guessing something is wrong with the amp after all. Don't have a schematic because the amp is like 15 years old and there is no literature on it. Is there anything that can be figured out from these pictures?

http://www.cs.mcgill.ca/~nyu3/IMGP1971.JPG
http://www.cs.mcgill.ca/~nyu3/IMGP1972.JPG
  Reply With Quote
Old 9th December 2007, 04:33 AM   #8
diyAudio Member
 
Join Date: Sep 2005
Location: Melbourne Florida
Default Hum

If the amp functions properly and the hum from the trans is random you might have DC riding the AC mains.
  Reply With Quote
Old 9th December 2007, 04:40 AM   #9
some1x is offline some1x  Canada
diyAudio Member
 
Join Date: Jan 2006
Location: montreal
Is there any way to test for that? Is it safe to measure DC in the AC mains using a DMM?
  Reply With Quote
Old 9th December 2007, 05:24 AM   #10
some1x is offline some1x  Canada
diyAudio Member
 
Join Date: Jan 2006
Location: montreal
Its gone again lol. Maybe it does have something to do with AC mains.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Is this box design strong enough ? Bigun Subwoofers 2 27th February 2009 02:02 AM
How strong does the box need to be? wasted911 Subwoofers 60 14th January 2008 02:29 AM
8x Mur 860 strong enough for 2 paralleled 4780? Bassterror Chip Amps 4 8th February 2007 02:02 AM
Strong solder, how does it sound? classd4sure The Lounge 33 23rd September 2006 10:47 AM
Line out signal too strong Mike Collard Everything Else 0 15th December 2001 07:47 PM


New To Site? Need Help?

All times are GMT. The time now is 07:38 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2