Opamp DC offset - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 21st May 2003, 05:04 PM   #1
diyAudio Member
 
Join Date: Sep 2002
Location: London, UK
Default Opamp DC offset

As a simple project I decided to so a simple preamp using high speed unity gain opamps as line drivers. One channel seems to work fine but on the other one there is a DC offset of about +7V on the +Vin pin, Im sure the wiring is correct, can anyone think of what the problem might be? Could it be that the chip is somehow damaged?


Any suggestions greatly appreciated


jnxw2
  Reply With Quote
Old 21st May 2003, 05:44 PM   #2
diyAudio Member
 
Tube_Dude's Avatar
 
Join Date: Mar 2002
Location: Aveiro-Portugal
Default The 7 volts ofset issue...

Quote:
there is a DC offset of about +7V on the +Vin pin, Im sure the wiring is correct,
Are you sure that this 7 volts are not in the source that is driving the + Vin pin?

If not...
Quote:
Could it be that the chip is somehow damaged?
yes...that's possible...

Cheers
__________________
Jorge
  Reply With Quote
Old 21st May 2003, 06:06 PM   #3
diyAudio Member
 
Join Date: Sep 2002
Location: London, UK
Sorry my mistake for not being clear enough, the DC Offset is on the non inverting input.
Also dont know if it is important or not but it is a current feedback opamp


jnxw2
  Reply With Quote
Old 21st May 2003, 06:28 PM   #4
diyAudio Member
 
Tube_Dude's Avatar
 
Join Date: Mar 2002
Location: Aveiro-Portugal
Quote:
Sorry my mistake for not being clear enough, the DC Offset is on the non inverting input
And the inverting input is at 0 Volts?
__________________
Jorge
  Reply With Quote
Old 21st May 2003, 06:41 PM   #5
diyAudio Member
 
Join Date: Sep 2002
Location: London, UK
Thats right, the inverting input is at 0V as is output.


jnxw2
  Reply With Quote
Old 21st May 2003, 06:45 PM   #6
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Default dc offset

We are really groping around in the dark here. A schematic (even rudimentary, hand drawn) would help YOU immensely.

Jan Didden
  Reply With Quote
Old 21st May 2003, 06:47 PM   #7
diyAudio Member
 
Tube_Dude's Avatar
 
Join Date: Mar 2002
Location: Aveiro-Portugal
Default The dead Ic...

Sorry...bad news...the Ic is dead!

It will rest in peace!!!

Amen!
__________________
Jorge
  Reply With Quote
Old 21st May 2003, 06:53 PM   #8
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Default offset

Not to spoil your party, but how do you rate the chance that the new opamp you put in will also die untimely? Where's the f<]u*#c*#k@i^%n@!g schematic??

Jan Didden
  Reply With Quote
Old 21st May 2003, 07:15 PM   #9
diyAudio Member
 
Join Date: Sep 2002
Location: London, UK
Yeah i was kind of coming to that conclusion aswell

Here is the diagram.

jnxw2
Attached Images
File Type: jpg dd.jpg (23.5 KB, 273 views)
  Reply With Quote
Old 22nd May 2003, 07:01 AM   #10
Werner is offline Werner  Europe
diyAudio Member
 
Join Date: Jan 2002
Location: Belgium
You connected the - input to ground???
  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
Cancelling DC Offset in a bipolar Opamp ygg-it Chip Amps 16 5th May 2008 04:47 PM
Two Questions, Reading leads on Opamp and Offset Trim pjpoes Parts 10 28th December 2006 09:06 PM
Single supply opamp - unequal rail voltage and opamp selection Hans L Parts 8 19th February 2006 02:15 PM
Opamp/DC-Offset Problem (Help!) MWP Chip Amps 9 9th September 2004 04:13 AM
opamp replacement & dc offset trouble Raj1 Digital Source 14 6th December 2003 11:56 AM


New To Site? Need Help?

All times are GMT. The time now is 08:36 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