amplifier help

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Joined
28 Aug 2003
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1,248
Location
N Ireland
need some suggestions - i run all my pc sound through a now ancient NAD304 amp. Something is dying in it as one speaker channel keeps cutting out unless i give it a tap on the top of the amp (i've taken the cover off but can't find any obvious cause - it is 18 years old now)

i'm looking for a basic replacement amp - it must have a front headphone socket and be able to run 2 sets of speakers. only thing i have seen so far is a marantz pm5004. budget is around 150 quid and i'd prefer new rather than 2nd hand if possible

any recommendations?
 
I don't think you can do better than the PM5004. You can get better, but you you're probably going to up the budget by a fair chunk to get a noticeable improvement.
 
When it loses the one channel, check it for hiss vs the other. (with no input turn the volume up and listen close to the tweeter on each channel. If you get nothing at all from the channel that cuts out, you know the problem lies between the amp circuit and the speaker. If you get hiss but your input cuts out, you know it lies between the input/preamp and the amp. If it happens on any input that narrows it down to the preamp. If the speaker does cut out completely, see if it still happens with headphones. Probably just a dodgy solder joint and it merely needs re-doing. Reflowing solder joints doesn't even cost you anything.

This site suggests the protection relay could be the cause. The service manual and some additional info is available here.
 
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