Some years ago I sent my NAD C340 away for repairs under guarantee. It kept cutting out and wouldn't switch between inputs. It wasn't repaired properly. When I got it back it had a horrible fuzzy noise in the right channel. I sent it back for repair through the retailers shortly before the guarantee expired. But it was again sent back with the same problem. I phoned NAD customer services. The man I spoke to was very unhelpful. He told me they were not going to bother. After being left unused for some years I took it to a local repairer. He isolated a transistor which needs replacing, but after searching he said he couldn't find a replacement. I only got about a year's good use from that amp. I am furious with the NAD UK distributors of that time - Lenbrook. The transistor spare part needed is 2FA949. Why should NAD make amps which become obsolete so soon? Any other solutions?
Odd a transistor would have such a #. No 2Fanything series. It is most likely a 2SA949.... a PNP audio driver transistor.
It can be replaced by a NTE-383 (ECG383) transistor, though it's best to order the original # from a Japanese semiconductor supplier like MCM in Ohio.
It's best brought to a good hi-fi or guitar amp repir shop for a proper go-thru & repair.
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Sometimes you can find the faulty part by touching the parts inside the amp. Only touch the plastic parts not any metal parts! As it is on one channel you have a good channel to compare the bad. Often small transitors can become noisy so start with them!
Hi there I have a C340 that has similar problem, you must have bought this from ebay, lol.
Nad made a mistake on the C range, the pre - power link can be shorted out. if the pre is shorted out it takes out the pre amplifier stage, I have managed to get the right channel working, I will keep you informed what is the cause of the left channel. I have replaced the pre-amp IC and a couple of Jfets and transistors. Once I have repaired the Amp I could repaire yours if you like???
Let's distill this down to its simplist configuration. FM source, stereo.
BTW, a search for NAD 440 only brings up a C440 >>>Tuner<<, no receivers. Are you sure about that model number? The only receiver model numbers with x40 on the NAD website are the C340 and C740, neither of which has a link to a manual (go figure). I have the C740 manual, so I'll use it for a loose reference.
If it still does what you're describing in a basic configuration and the volume control seems to affect it like you belatedly mentioned, I'd suspect a noisy volume control or some other control in the receiver (like a rarely used Tape Monitor switch) that is always there in the circuit but may have oxidized contacts and responds sometimes to burn-through.
Set the volume at a medium setting and repeatedly operate every switch, knob and button (one at a time) to gauge its effects on the sound. You may find one is the culprit. Then it's a matter of accessing it for a shot of contact cleaner.
If you have jumpers between Pre Out and Main In, it might be a good idea to reseat them, too.
I have the same problem which started about a month ago and seems to be getting worse.
I also noticed today, that 1 channel is significantly louder than the other - fault in the pre-amp stage, as feeding the power stage directly gives balanced, albeit extremely loud sound!
Looking on eBay, I found someone else selling an amp with both problems. It would nice to think that NAD would acknowledge a design flaw, and fix for free, but my amp is 5 year old.