[sillyputty]

Recently purchased a used NAD AV-716 receiver (I know I took a risk
buying a 90s receiver and having it shipped, but am prepared to pay
for repairs). Sometimes one channel or the other of the mains cuts out
(the headphones don't), but when the volume is turned up it comes back
on. I checked the speaker connections and they're OK. Something going
south?

[Arny Krueger]

"sillyputty" wrote in message


Recently purchased a used NAD AV-716 receiver (I know I
took a risk buying a 90s receiver and having it shipped,
but am prepared to pay for repairs). Sometimes one
channel or the other of the mains cuts out (the
headphones don't), but when the volume is turned up it
comes back on. I checked the speaker connections and
they're OK. Something going south?

There's a bad connection, someplace. An insulating oxide layer is forming,
and then the loud music punches a hole in it, and the sound comes back for a
while. Bad solder joint?

[Tim Schwartz]

sillyputty wrote:
Recently purchased a used NAD AV-716 receiver (I know I took a risk
buying a 90s receiver and having it shipped, but am prepared to pay
for repairs). Sometimes one channel or the other of the mains cuts out
(the headphones don't), but when the volume is turned up it comes back
on. I checked the speaker connections and they're OK. Something going
south?

Hello,

While I'll agree with Arne that there could be a bad solder joint
somewhere (look at power supply voltage regulators and the driver IC's
for the amps.), you could also have bad speaker relays, or noisy pots.
(Treble, bass, balance or maybe volume controls.)

If you take this receiver to a repair shop, have them replace R921, R
922 and R923 (all 0.47 ohm ) and R924 (33 ohm) resistors with half watt,
flameproof type, if they have not been replaced already. They are on
the near the front edge of the main board. The original ones are 1/4
watt and are subject to open for no reason. This is a common problem in
the NAD AV716, but is NOT what is causing your current problem.

Regards,
Tim Schwartz
Bristol Electronics

[Dave]

"sillyputty" wrote in message
...
Recently purchased a used NAD AV-716 receiver (I know I took a risk
buying a 90s receiver and having it shipped, but am prepared to pay
for repairs). Sometimes one channel or the other of the mains cuts out
(the headphones don't), but when the volume is turned up it comes back
on. I checked the speaker connections and they're OK. Something going
south?

If the headphone doesn't cut out, it's gotta' be the speaker protection
relay. Everything else is common between the headphone jack and speaker
jacks. This is a common ailment with older equipment. You'll have to
either replace the relay(s) or remove them from the board, open them up
(sometimes you can, sometimes you can't) and clean the contacts with a fine
emery board. I use a points file, used to clean the contacts between the
points before electronic ignition was common in cars... it's just the right
size for that sort of work. The relays themselves shouldn't be expensive
and they're very simple to replace if you've got rudiementary skill with a
soldering iron.

Dave

[UnsteadyKen]

Dave said:

If the headphone doesn't cut out, it's gotta' be the speaker protection
relay.

I have a similar problem with a Denon receiver, ie one channel down
in volume reference the other cured by a tweak of the volume control,
I noticed that it only occured if I switched on with no signal input
or with volume control set very low. I get round it now by setting
input to tuner with highish volume when I switch on and have no
problems for that session. Give it a try.

--
Ken
Contribute to: www.audiophilewiki.org

[Dave]

"UnsteadyKen" wrote in message
m...
Dave said:

If the headphone doesn't cut out, it's gotta' be the speaker protection
relay.

I have a similar problem with a Denon receiver, ie one channel down
in volume reference the other cured by a tweak of the volume control,
I noticed that it only occured if I switched on with no signal input
or with volume control set very low. I get round it now by setting
input to tuner with highish volume when I switch on and have no
problems for that session. Give it a try.

--
Yes the relay contacts get oxidized. A strong signal is able to arc through
the oxidation and get a connection established, but the oxidation acts as a
weak insulator.

[UnsteadyKen]

Dave said:

Yes the relay contacts get oxidized. A strong signal is able to arc through
the oxidation and get a connection established, but the oxidation acts as a
weak insulator.

Thanks for the info, I thought that this was what was causing the
problem. I might have a go at cleaning up the contacts as someone
suggested, but from what I remember when I last had the lid off, they
appear to be sealed units. It's livable with.
--
Ken