NAD 304 schematic wanted

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If there is no schematic .. where should I start to look ?

After the amp warms up one channel starts to break up very badly, while the other channel suffers the same fault but only very slighty.

I have not yet opened this amp up to look about as without a diagram I would be lost.

Any suggestions would be appreciated.
 
hmm i got one of these too...so if anyone's throwing schematics around,i would be very greatful to get one as well...

i had some problems with mine as well,and i don't know if this would be the same or even related...mine just wouldn't turn on and got stuck in protection mode...anyway in addition to any other problems anyone's having... you want to double check the values and integrity of these components

preamp section- R917/R918 these are 180 ohm and should be changed to 1 watt if they installed 1/2 watt..check to make sure they work and aren't cooked if you have 1/2 watt's installed![some apparently do]

main Amp - R333/R334 are the same deal..47k 1/2 watt and should be 1 watt..these suckers get HOT,hot enough to discolor the PCB..these cause the "protection fault" when they let go and tend to drift up to very high values before...DEFINATELY check em and replace if necessary...from what i can gather this was a VERY common failure with this model..when blown the amp becomes completely non functional,but the fix is easy...just replace em,their failure doesn't appear to do any other damage :)
 
oops i forgot my email :xeye: if anyone would be kind enough to pass on the schematic,it would be most appreciated...

rodmowery@hfx.eastlink.ca

i should mention as well that the parts and fixes i mentioned in my last post are not just from my own brain and experience,but are reportedly from NAD service bulletins,factory recommended and approved as it were...for reliability these parts should be swapped/checked. :)
 
Rodzilla, I just wanna thank you for this information regarding the NAD 304 and the 4 prone-to-failure resistors. My amp blew up the other day, and whilst searching for a service manual, I found this thread (I've registered just so as I can reply!). I don't know electronics so I'd never have found it myself, but I checked all 4 resistors, and R334 was behaving odd. So I replaced it at the cost of 35p (well I splashed out on 2watt!), and the amp works fine again. So thanks for the info - saved me a bundle.

Incidentally, the amp went when I was trying out a new sound module I'd just received. The output was set to pan hard left. I heard a brief bit of the sound, less than a second, before it went. So I don't know if the 304 is prone to blowing when one channel is far louder than the other (which would have been silent). I'd consider trying it, but then like I say, it's a 2W one in there now anyway.

Thanks again,

Andy
 
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