nad 2400 thx amp schematic

[steven344]

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]

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

www.sharefx.com

 

[steven344]

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.

 

[damage]

-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.

 

[Jonas83]

I guess there are several differences between 2400 & 2400 thx (?) can´t find any specific 2400 thx ser.man but plenty of the 2400. anyone who has the thx service manual scraping around? or know the differances.....