Naim CD5i problem - opamps - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, etc.

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 11th July 2012, 09:28 AM   #1
diyAudio Member
 
Join Date: Dec 2011
Location: Leatherhead, UK
Default Naim CD5i problem - opamps

Folks

I need some help on a problem which has me baffled: i replaced the 2 x OPA604 output opamps in my Naim CD5i with 2 x OPA827 on Browndog adapters. I liked the sound, which improved over the course of a few weeks as they burned-in, so decided to replace the other 4 x OPA604's (the i/V stage?) with 4 x OIPA827's on Browndogs. I then powered up and can hear only the left channel.

I've covered the basic problem solving steps:
  • Continuity checked the signal path from the first Opamp, through to the socket on the back of the player.
  • Swapped Browndogs for new ones and replaced the 2 x OPA827's in the faulty channel.
  • Checked for any shorts on the pins of the opamps and adapters
  • Replaced the Reed relay on the output.
  • Switched interconnect cables and checked my amp input with another CD source.
Still no joy - oddly, the right channel does work very briefly for ~1-sec, after a disc has been playing for ~20-secs, then it goes again for good.

I was wondering if the OPA827 is simply not a good drop-in replacement for the OPA604 in the i/V stage? But then why would the left channel work and not the right? Perhaps it's operating on the limit of its spec. Can anybody help guide me on this, because i've run out of ideas! (other than replacing the 827's with 604's, which i've not done yet)

Will
  Reply With Quote
Old 11th July 2012, 10:58 AM   #2
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
The most likely cause is something physical such as broken or open print or a solder blob somewhere.

Careful voltage measurement should reveal the problem. Check the DC voltage on the output of all the opamps. Usually (but not always so compare left and right) this will be around the zero volt region.

It is just possible the opamps could be unstable for some reason and is something that should be checked as a matter of course. The symptom of it working for a second and then not could possibly suggest a floating input and the bias voltage just happens to "float" through a window where it works.

Swapping Op-Amps... you have checked to see it's stable haven't you ?
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  Reply With Quote
Old 11th July 2012, 11:12 AM   #3
diyAudio Member
 
analog_sa's Avatar
 
Join Date: Aug 2002
Location: Sofia
Buy a scope. Learn how to use it.
  Reply With Quote
Old 11th July 2012, 02:40 PM   #4
diyAudio Member
 
Join Date: Dec 2011
Location: Leatherhead, UK
Thanks Mooly - that gives me another angle to work with. I did check voltage on the outputs and it moves above and below 0V by a few points, but i'll do it again with a more critical eye.

As for the scope - you're right - I was looking at them the other day! More a question of funds right now, than the desire to own one, hence the reason i didn't want to chuck more money at this issue...

BTW - i had excellent audio results with the OPA1641/2/4 series in my VDac-2 - now they've burned in, they are really musical. I put another post up on here about that.

Will
  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
Naim CD5i and CD5x dueeffe Digital Source 2 25th May 2010 09:16 PM
Naim cd 5i problem greierasul Digital Source 0 2nd December 2008 10:14 AM
Naim NAP250 Regulator Instability Problem ceharden Solid State 9 29th April 2008 09:22 PM
Naim Nait5i + squeezbox problem Banfi T. Solid State 5 13th October 2007 10:28 AM
NAIM CD5 - opamps Fidelity Audio Digital Source 18 10th September 2007 01:54 PM


New To Site? Need Help?

All times are GMT. The time now is 07:15 AM.


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