Troubleshooting NAD C350 - 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 17th October 2008, 08:26 PM   #1
diyAudio Member
 
Join Date: Aug 2003
Location: Houston, TX
Default Troubleshooting NAD C350

I am having a problem with my NAD C350. Upon power-up the green power light turns on and then fades to red as the protection circuit kicks in. I have inspected the boards and nothing looks obviously blown. All the fuses are good and the power supply is outputting its +/- 40 volts properly. I am not sure what to check next.

I have searched here and other places on the web and have read about many other people encountering similar issues but I have yet to read a solution to the problem. If anyone has a suggestion on what to check next it would be appreciated.

Thanks
Robert
  Reply With Quote
Old 18th October 2008, 04:33 PM   #2
diyAudio Member
 
Join Date: Aug 2006
heres the solution
Attached Files
File Type: pdf nad-c350_page_3-00-02.pdf (7.3 KB, 204 views)
  Reply With Quote
Old 18th October 2008, 06:53 PM   #3
diyAudio Member
 
Join Date: Aug 2003
Location: Houston, TX
Quote:
Originally posted by reddish75
heres the solution

Thanks for the suggestion. I immediatly checked those resistors but it looks like the manufaturer already beat me to it. The two "resistors" were just jumpers anyway. I guess my unit was made after the original problem was found.

Thanks again, you got me very excited for about five minutes!

Robert
  Reply With Quote
Old 18th October 2008, 08:20 PM   #4
diyAudio Member
 
Join Date: Aug 2006
i'll have another dig around, i'm pretty sure there was another service bulliten for this amp, another thing to consider is that the output transistors have blown, you can check this by measuring voltage on the relay, high voltage (meaning almost always power supply voltage) means transistors have blown somewhere
  Reply With Quote
Old 19th October 2008, 02:34 AM   #5
diyAudio Member
 
Join Date: Aug 2003
Location: Houston, TX
That would be great if there was antoher service bulletin. Thanks a lot for checking.

Sorry for the noob question but where is the relay?

Robert
  Reply With Quote
Old 19th October 2008, 02:08 PM   #6
diyAudio Member
 
Join Date: Aug 2006
hi, the service bulliten is not for your problem, however i have found somemore, have a good look around eveywhere under a bright light looking for burnt components if you find any i have service information relating to this, the relay should be a plastic rectangular box maybe an inch or so high.
  Reply With Quote
Old 19th October 2008, 08:00 PM   #7
diyAudio Member
 
Join Date: Aug 2003
Location: Houston, TX
I just measured the relay voltage and it is reading 49V between pins 1 and 4 and also between 8 and 5 according to the pin designation of the specification sheet linked to below. The relay is rated for 24V so I am guessing this is bad. All the other pin combinations read 0V.

http://www.ziming.sh.cn/zm/relay/pdf...nqi/ftr-f1.pdf

I did not see any burnt components or burned places on the boards but I will keep checking.
  Reply With Quote
Old 20th October 2008, 12:44 PM   #8
diyAudio Member
 
Join Date: Aug 2003
Location: Houston, TX
Update:

Something I did not mention earlier is that this problem is intermittent. That said, I noticed the power light had shifted back to green so I checked the relay voltage again and pins 1 and 4 read 24V while 8 and 5 still read 49V. Referring to your earlier post perhaps the output transistors are blown.

The green light didn't last long. Later in the day it switched back to red and both sides of the relay read 49V.
  Reply With Quote
Old 27th October 2008, 07:33 PM   #9
diyAudio Member
 
Join Date: Aug 2003
Location: Houston, TX
The current status of the amp is if it is left turned on for a long time the red protection light goes off and the green light comes on, as if the amp does not work until it warms up. If this indicates that the output transisotrs are blown how do I go about checking them? Do I have to remove them from the board?

Thanks,
Robert
  Reply With Quote
Old 27th October 2008, 10:39 PM   #10
diyAudio Member
 
Join Date: Aug 2006
i, dont think its the output transistors, it could be the power supply caps, ive had this problem with one of the nad classic series before i think the c320, just have a close look at them look for swelling, leakage check there firmly conected to the circuit board. maybe post a picture if you can.
  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
What problem with Nad C350 amp. Please help Pass lover Solid State 4 30th August 2009 11:21 PM
Nad C350 burbeck Solid State 0 18th December 2007 02:32 PM
looking for a nad c350 schematic neurot Solid State 0 4th December 2006 06:29 PM
Tweak/mod NAD C350 Pound0sound Chip Amps 7 27th February 2004 10:49 AM
Tweak/Mod NAD C350 Pound0sound Solid State 0 9th February 2004 03:01 PM


New To Site? Need Help?

All times are GMT. The time now is 02:06 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