On Mar 30, 5:47 pm, "Dallas" <Cybnorm@[EMAIL PROTECTED]
> wrote:
> My NAD 314 has developed both a nasty little hiss and a hum. I'm
wondering
> if there are some rules of thumb for tracking down these symptoms.
>
> I use generic cheap (Radio Shackish) RCA cables, I'm not sure if they
are
> really ****elded. Could that be it?
>
> I do have the ground terminal connected to the NAD, disconnection it
makes
> no difference.
>
> Any ideas?
>
> Dallas
OK... I am leaping to conclusions but here goes:
The last amp (receiver, actually) I had that developed a hiss/hum
turned out to have eaten one-each driver transistor (of a pair) and
electrolytic cap in the power-supply. I also repaired an NAD receiver
with a vicious hiss - that was one of the output transistors. It did
help in the diagnosis that the hiss was only in one
channel and the hum was irrespective of volume control position.
Some things that are external and can develop over time and be cured
easily:
a) Corrosion at the interconnects. Clean them.
b) Dirty and/or intermittent controls. Clean them.
This should be done at regular intervals anyway, frequency being
dependent on the general environment. Smokers, city dwellers and those
with cats/dogs/children more-so.
If this is something that has "developed" recently with no other
changes, I would first isolate it to the amp (disconnect everything
except the speakers and see what happens), then I would be looking to
internal components within the amp if it persists.
If this is something that developed since you made a change to
components, then look to cables, grounding and so forth.
Peter Wieck
Melrose Park, PA
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