Hello all, first up I have to say I know very little about audio equipment so please go easy on me!
I have recently been given an amp (NAD C 300) and some (what I'm told are) nice speakers, that had both been working but kept in a loft for maybe 4 years. The plan was to run the audio from my computer through the amp.
I connected the computer (Intel 2 Core Duo iMac) to the AUX input of the amp from its "Headphone Out" socket. I was careful to turn the volume right down on the computer before slowly going to about 50%. All worked great and sounded superb for about 30mins. I turned the volume down on the amp walked away, came back about an hour later and the amp seemed to have turned itself off. On trying the power button the LED next to the power button flashed red but then died. I tried once more and a whisp of smoke came from the amp and died completely, no LED.
So my questions are. Is this my fault? Someone now tells me that I should only use a lineout to connect to the amp as the headphone output will be too strong? I don't think my Mac has a lineout however? What should I have done?
Also is there anything I can do to diagnose the problem? I'd preferably like to have some kind of idea before I take it to repair. Are these things cheap to repair and is it even worth it?
Any help would be much appreciated, sorry for all the novice questions!..
Stored electronic components age faster that those in use. You probably damaged the power supply of the amplifier. Smoke typically means you've increased the cost of repairs by a magnitude in coherence with the amount of smoke released and how loud you shouted when you first smelled the smoke (and sometimes how far back you jumped when the amplifier blew up while releasing the smoke). So, it's a compound equation and there is no set answer for your question regarding cost. I doubt this will be "cheap" to repair when you can buy another receiver for less than $100. If you want to get an estimate of cost, any repair shop will charge a minimal amount for that service.
I had a NAD amp repaired a few years back for about 100 bucks. I never had any smoke emit from it, so Jan's formula here relating repair cost as a function of amount of smoke released would most definitely apply.
If the cap didn't take something really pricy with it when it popped, you might consider replacing all of 'em. The amp should than be good for another decade.