Hi everyone,
My poor NAD C320 has decided to give up...
The last time I fired her up, one channel wasn't working, but this was fixed by twiddling the balance control... after that she played as usual.
This evening she won't play at all. I opened her up and used switch cleaner on the pots, but still nothing.
The output stage and preamp section looks fine and there are no obvious signs of missing smoke.
If I plug her in and turn the volume to max, I can faintly hear the music if I put my ear to the speaker, but only through the one channel. The other sounds almost completely dead...
Any ideas on what this could be? What steps should I follow for a diagnosis?
Thanks in advance,
Chris
My poor NAD C320 has decided to give up...
The last time I fired her up, one channel wasn't working, but this was fixed by twiddling the balance control... after that she played as usual.
This evening she won't play at all. I opened her up and used switch cleaner on the pots, but still nothing.
The output stage and preamp section looks fine and there are no obvious signs of missing smoke.
If I plug her in and turn the volume to max, I can faintly hear the music if I put my ear to the speaker, but only through the one channel. The other sounds almost completely dead...
Thanks in advance,
Chris
The last time I used it was in a setup where the pre and power sections were seperated by an active crossover... This time I forgot to put the pre/power links back in... DOH! She's back and sounding good... Thanks anyway
This has however made me wonder about the signal bleeding into the shared ground :/
Hi,
I would proceed as follows, as with any normal commercial amplifier:
volume at minimum, switch on amplifier, do you hear a click after 5...10 seconds?
(loudspeaker relay engaging)
If yes, most of the amplifier is O.K.
Clean controls with a good contact cleaner.
If not,
1. check for solder joints that have become bad on the main printed circuit board.
2. check or replace electrolytic capacitors in the speaker protection circuit.
Check output signal with oscilloscope before the speaker protection relay.
Left and right output should be present.
If not, service by a competent service engineer is needed.
Regards, 968driver.
I would proceed as follows, as with any normal commercial amplifier:
volume at minimum, switch on amplifier, do you hear a click after 5...10 seconds?
(loudspeaker relay engaging)
If yes, most of the amplifier is O.K.
Clean controls with a good contact cleaner.
If not,
1. check for solder joints that have become bad on the main printed circuit board.
2. check or replace electrolytic capacitors in the speaker protection circuit.
Check output signal with oscilloscope before the speaker protection relay.
Left and right output should be present.
If not, service by a competent service engineer is needed.
Regards, 968driver.
The faint audio when the links were omitted is more likely due to stray capacitive coupling rather than ground comtamination.
It would be really helpful do others if the thread starter clarify the cause of such a problem or if "left unsolved".... have the same amp with same problem (obviously, tought it was good until i wanted to use it....), guessing some bad cap somewhere as the problem tend to come with heat and "juice" (did a proper offset/idle adjustment on it, seems fine) as today i do not have any gear (exept my scope and gen) for checking leaky caps. This might even be "preamp issue" (read that somewere long ago..) well, pointers will be appreciated 🙂
Seems like this is infact a preamp issue (mine anyway). Some caps in preamp looks funky, looking for that esr meter........
That is very true...
That is very true...
Last edited:
Okay.... stupid me... not a problem with preamp section, the reason for one channel not giving output was the output relay (and my crappy cable from pre to main), tapping it solves problem. Negative supply cap (15kuF) was a bad "cold joint" works and sounds very much better now when fixed. I do have a question regardning a "full recap" (elytes) is this a bad thing or a good thing? any reason for it other than age or obvious bad cap?. some say this ruin original sound while other say it restores it. some caps do look cheesy so.... just thinkering, good or bad? it´s not really that much of trouble changing or money.
- Status
- Not open for further replies.