nad 2400 thx amp schematic

steven344 · 7th May 2006, 02:39 PM

Does anyone have a schematic fo a Nad 2400 power amp,I have 3 units with the same problem of not coming out of protections.They do not have any dc offset and no fuses are blown.It seems to be a problem with the protection IC that drives the speaker relays.

computeruser · 7th May 2006, 03:08 PM

The service manual for this unit has just been posted on:

www.sharefx.com

steven344 · 9th May 2006, 11:45 AM

Thanks,I figured out the problem.I had 3 of these to repair for a customer.They were all in protection but had no dc offset.The protection circuit was on because of C817 a 4.7 mfd was leaky.Once audio was applied both channels would go into protection because C818 was leaky a 220mfd.Also C403 and C453 was leaky in the diff amp cause protection with audio applied.In the power supply as preventive measure C810 and C811 was replaced because of open tops of the caps.They get heated up from the nearby regulators.These amps also have alot of bad solder connections that needed to be retouched.Its worth the time to go over the pcb and retouch any connections that appear suspect.

damage · 9th October 2008, 04:56 AM

-1.5V DC offset on Left channel caused protect. Replaced C403 and music was restored.

Obviously, this one is an easy one to do total recap on, just thought I would share.

7th May 2006, 02:39 PM	#1
steven344 diyAudio Member Join Date: Jun 2005 Location: ohio	nad 2400 thx amp schematic Does anyone have a schematic fo a Nad 2400 power amp,I have 3 units with the same problem of not coming out of protections.They do not have any dc offset and no fuses are blown.It seems to be a problem with the protection IC that drives the speaker relays.

9th May 2006, 11:45 AM	#3
steven344 diyAudio Member Join Date: Jun 2005 Location: ohio	nad 2400 Thanks,I figured out the problem.I had 3 of these to repair for a customer.They were all in protection but had no dc offset.The protection circuit was on because of C817 a 4.7 mfd was leaky.Once audio was applied both channels would go into protection because C818 was leaky a 220mfd.Also C403 and C453 was leaky in the diff amp cause protection with audio applied.In the power supply as preventive measure C810 and C811 was replaced because of open tops of the caps.They get heated up from the nearby regulators.These amps also have alot of bad solder connections that needed to be retouched.Its worth the time to go over the pcb and retouch any connections that appear suspect.

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7th May 2006, 03:08 PM	#2
computeruser diyAudio Member Join Date: Dec 2004 Location: Montreal	The service manual for this unit has just been posted on: www.sharefx.com

9th October 2008, 04:56 AM	#4
damage diyAudio Member Join Date: May 2006	-1.5V DC offset on Left channel caused protect. Replaced C403 and music was restored. Obviously, this one is an easy one to do total recap on, just thought I would share.

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