Go Back   Home > Forums > >

Chip Amps Amplifiers based on integrated circuits

Buzz/Hum from Audiosector LM3876 board itself - no buzz in speakers
Buzz/Hum from Audiosector LM3876 board itself - no buzz in speakers
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
Old 11th April 2014, 07:45 PM   #1
dakku is offline dakku
diyAudio Member
 
Join Date: Oct 2013
Default Buzz/Hum from Audiosector LM3876 board itself - no buzz in speakers

I have a distinct buzzing/hum from the actual amp board. Its like the hardware is making the buzz, but I do not hear it in the speakers, just directly from the amp..

For the starground I have joined the ground wires from the following to a single point (not connected to the chassis):

Mains Ground
PG1+ and PG- (rectifier)
Left amp OG
Right amp OG

Any ideas?
  Reply With Quote
Old 11th April 2014, 07:49 PM   #2
dakku is offline dakku
diyAudio Member
 
Join Date: Oct 2013
I disconnected the speakers, hum is still there
I disconnected the RCA in, hum is still there
  Reply With Quote
Old 12th April 2014, 10:20 AM   #3
AndrewT is offline AndrewT  Scotland
R.I.P.
 
Join Date: Jul 2004
Location: Scottish Borders
Do you have a mains bulb tester?
If not, build one and use it.

Does the bulb flash, or glow, or light up bright, when you start up?

Have you measured the voltages at the output?
Have you shorted the input?
__________________
regards Andrew T.
  Reply With Quote
Old 12th April 2014, 12:26 PM   #4
danielwritesbac is offline danielwritesbac  United States
diyAudio Member
 
danielwritesbac's Avatar
 
Join Date: Nov 2007
The concept:
Click the image to open in full size.
image by antiqueradio.org
The bulb is incandescent, both standard and halogen work, and 25W fridge bulbs and 40W clear oven bulbs remain widely available.
__________________

Last edited by danielwritesbac; 12th April 2014 at 12:30 PM.
  Reply With Quote
Old 12th April 2014, 03:51 PM   #5
Leglandu is offline Leglandu  France
diyAudio Member
 
Join Date: Dec 2004
Location: Parisian suburbs
Default my 2 cents (of euro)...

Quote:
Originally Posted by dakku View Post
... Its like the hardware is making the buzz... Any ideas?
Hi dakku... as you already disconnected the speakers... some ideas :

- transformer vibration (toroidal no tight enough, DC component on the 120 or 230VAC...) ?
- toroidal incorrectly mounted on metalic surface with metal screw creating a kind of secondary short-circuit ?
- defective chemical cap or cap enclosure in contact with a rigid structure ?
- inverted polarity or alternative current (bad diode) on cap...
  Reply to this post

Reply


Buzz/Hum from Audiosector LM3876 board itself - no buzz in speakersHide this!Advertise here!
Thread Tools

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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
hum/buzz with pot all the way up woodturner-fran Tubes / Valves 24 7th May 2021 07:16 PM
Threshold SA3 buzz / hum in speakers Tino Pass Labs 1 10th February 2008 07:24 AM
Melos triode and computer as source: BUZZ BUZZ BUZZ zigo3 Tubes / Valves 4 28th November 2007 03:11 AM
transformer hum / buzz getting into B+? cbutterworth Tubes / Valves 3 18th August 2007 02:49 AM


New To Site? Need Help?

All times are GMT. The time now is 12:41 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright ©1999-2021 diyAudio
Wiki