On my NAD 304 ampilfier, one channel is stuck at maximum gain, even with the volume knob all the way down. The other channel seems to work fine. I've checked the RCA connections, and tried a few different inputs (CD / Tape specifically). The problem seems to be in the preamp section, as if I connect an external preamp to the amp section, things seem to work OK. Is this something reasonably common such that I'd know where to look for a DIY fix, or is the amp ready for the bin?
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Re: Gain on one channel stuck at max
Check for a dry solder joint on one end of the vol control(earthy end). This will be causing your problem. The pot itself may actually be faulty to. You can always get stuff like that, just got to identify it. Check soldering to the pot first.
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Take care. First put the volume down complete. Then unplug the head phone and than try to raise the volume. Could be the headphone connector does not switch through correct. Could be the connections between the pre and power amp are not in place or not proper pushed in? Always take care when working with amplifiers. When switching them on with volume to max, you easy can kill your speakers. Also when disconnecting the headphones on full power kan damage the loudspeakers.
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???
One way of proving it ISN'T the amp circuitry is to remove the pre-main jumpers and jack in a source that has its own volume control (or try a CD that starts really low) because this bypasses ALL the amps controls. If it sounds ok (albeit LOUD) I'd suspect oxidized contacts on the controls. Turn it off and vigorously operate all controls a zillion times to wear through it. In mosty cases it's the unused controls that fail because they never get wiped. Maybe a shot of contact cleaner on those you can access.
Only the right channel had a sound,the left channel is mute, whatever adjustment you did and whatever balancing you done nothigs happen,even you interchange the speakers. The problem is in the power amp. The STK IC there is busted already, it's better to change it with a new one so the performance become normal again.
The potentiometer (volume control) is probably dirty. Open the amp and find the "pot" connected to that volume control. You should be able to see small opennings where you can spray electrical contact cleaner inside. Give the knob a few turns and try it out. If it gets better but not perfect, repeat. If several attempts don't eleminate the problem, the pot will most likely need to be replaced. Contact cleaner can be found at any electrical supply store such as Radio Shack. Be sure to use one that says no or zero residue. I use a product called Electrosolve.