20 Most Recent NAD C350 2-Channel Amplifier Questions & Answers

See link below.

http://www.pithed.org/2007/10/12/nad-c370-protection-circuit-repair-amp-fails-goes-into-protection-mode/

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.http://www.overload.it/supporto/643/manuali/NAD-C350.pdf

On the back you'll probably find it has it's own AC fuse in an unscrew cover/capsule which has a clear glass body with two metallic ends. If it looks OK you'll see a silver strand (sometimes copper) of wire inside, if not you'll see it's shredded and somewhat burnt remains.
On the metal end tips will be the info on what rating and type the fuse is. Most eletrical stores will supply another.
If fuse is OK put it back.
If this arrangement isn't there check all info on the back panel looking for any mention of internal fuse.
That means the same type of fuse is in a holder inside the AC-DC unit of the circuitry and I can't advise you to take the cover off and look for it and replace it unless you really are familiar with the innards of equipment.
Check the book if you've got it.
By now, if no further on it's repair shop time.

Read the manuals...

http://www.mordauntshort.com/assets/documents/Premiere_Manual.pdf http://www.retrevo.com/support/NAD-C350-Amps-manual/id/8043dj589/t/2/

With no background on the original problem and no details regarding what parts were replaced how can anyone answer the question?

What exactly does it mean if 'everything works' but it has 'no sound output'? As a two channel amp that would be its ONLY function.

The root cause for 'no sound' could be something as simple as a misplaced control (Tape Monitor?) or missing pre-out/main in links. It's in the manual.

Register and download it for free at retrevo.com

http://www.retrevo.com/support/NAD-C350-Amps-manual/id/8043dj589/t/2/

If the sound stays with the speaker, then the problem is with the speaker not the receiver (unless I misunderstand). You state that changing the speakers that the sound stays with the speaker. This means that both channels are producing sound, it is the speaker which is defective. You can verify this by using a 9V battery. Quickly touch the leads from the speakers to the battery. You should hear a pop or click. If the speaker is defecive, you won't hear anything.

Let us know what happens.

Dan

http://remotes.com/remotes/servlet/rs?a=gmi&uuid=A13018287157011&smodel=C350&brand_pn=NAD_C350

The first thing to do is check or more likely replace the power output devices (located on the massive heat sink) on the faulty channel. Then look around for burnt and damaged parts. You might need to replace bias resistors on that faulty channel, which are connected with the output devices. If it powers up as it stands the power supply section should be OK.

This is a power overload protection circuit, to prevent you from blowing out your speakers. It's measuring the amperage through the circuit; I suspect you have a short-circuit in your speaker cables (do you have pets?).

To check, disconnect all speakers, then add one at a time until the problems appears. When it does, that's the speaker wire to check.

Replace it with another cap of the same value and voltage rating. Check other nearby components for damage.

Can't help on power problem, but the other sounds like an IC has failed that controls input selection. If you are going to do it yourself you will need a circuit diagram to find the IC.

Providing the effect is there on all inputs, plus there's no distortion, the problem could be caused by an Electrolytic bypass or coupling Capacitor in the pre-amp stage or higher.
If there's distortion, the problem is in the main power amp, with the 'things' on the heat sink.

If you follow the cd input to the pc board and trace the course of the channels, my guess is you will come accros an IC. Touching the pins of this with a tiny screwdriver (be carefull not to touch two pins at the same time) should produce a buzz on either channel. If it doesn't and there's not another IC further along the path of the signal, (that could be causing the loss) then it will most likely have gone.

Hi...

Have you checked the rectifier diodes / bridge rectifier . Most DMMs have setting where you can test for forward voltage drop on a diode
0.300- 0.800v depending on the type. If it reads nothing , swap the meter leads.
Also check the leads coming from the power transformer and see if there's continuity. THey will read low value ohms

I don't know of the availability of the schematics outside of service centers. Is there a specific problem? I have access to the service manuals but can not by contract send them out.
Dan