Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
N Cook
 
Posts: n/a
Default Omni i/o 2 channel preamp to pc a/d

No abuse apparently, owner plugged in a new microphone and blew one channel.
Seems to have knocked out expensive instumention op-amp ( comparing the 2 ).
I don't like the look of the electrolytic at the input, no input dropper
resitor and a 48V
phantom supply involved. Anyone any ideas ? don't fancy spending out on
an expensive Burr Brown IC if it is only going to happen again.
I've not often dealt with kit with phantom supplies - can any one
direct to a resource of generic probs associated with 48V on signal inputs?

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/




  #2   Report Post  
N Cook
 
Posts: n/a
Default

"N Cook" wrote in message
...
No abuse apparently, owner plugged in a new microphone and blew one

channel.
Seems to have knocked out expensive instumention op-amp ( comparing the

2 ).
I don't like the look of the electrolytic at the input, no input dropper
resitor and a 48V
phantom supply involved. Anyone any ideas ? don't fancy spending out on
an expensive Burr Brown IC if it is only going to happen again.
I've not often dealt with kit with phantom supplies - can any one
direct to a resource of generic probs associated with 48V on signal

inputs?

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/





There is 2 6.8K resistors from the 48V line to each of the balanced mike
lines , so protecting the phantom supply.
Each of these mike lines is connected via a 10uF/100V electrolytic directly
to + and - inputs of the op-amp.
So if a short to ground at the mike then the +48V side of the electrolytic
goes to 0V and the other side must go to -48V
or at least try to , op-amp supplies +-15V.

Modification of clamping diodes at the + and - opamp inputs?


Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Problem with right channel on Sony STR-D790 Receiver Chris L. Electronics Repair 5 January 19th 05 04:46 AM
Car Cassette Deck-1 Channel Dead JR NORTH Electronics Repair 3 August 17th 04 09:00 PM
Channel 3 fizzed out tRevHead Electronics Repair 1 April 2nd 04 08:35 PM
static on right channel of kenwood receiver Sofie Electronics Repair 22 July 20th 03 03:18 AM


All times are GMT +1. The time now is 10:37 AM.

Powered by vBulletin® Copyright ©2000 - 2023, Jelsoft Enterprises Ltd.
Copyright 2004-2023 DIYbanter.
The comments are property of their posters.
 

About Us

"It's about DIY & home improvement"