Tim,

The PSX-2405 original relays are no longer available. Do you know of a
drop-in replacement? The 2405 has a rather odd physical pinout.


Mark Z.



"Tim Schwartz" wrote in message
...
Danny,

The correct procedure for setting up (from the service manual) a NAD
2400 is:

1) Set unit to 8 ohm operation

2) confirm that DC output at speaker terminals is less than 100mV with
no load. If it is higher, then the amp needs to be repaired, and the DC
offset protection may be tripping.

3) Measure between TP 401 and 402 (TP451 and 452 for right channel) and
adjust R418 (R468 for right channel) for a reading of 14 +/-1 mV. The
amp should be cold when you do this, and then check again after 5
minutes. If anything I'd go a bit on the low side for cooler running,
but you should be able to get them to spec. The ambient temperature of
your room will have some effect on it too.

Note that the test points are specific leads of the dual emitter
resistors in each channel and should be marked on the circuit board.

4) set back to 4 ohm operation

The heat sink should not be uncomfortable to touch at any time.

Also, as I recall the speaker relays sometimes go bad in these amps.
When a channel cuts out, gently tap on the relays, and if that get the
channel back on, then replace them. You should be able to get sealed
contact replacements for around $10 each. I suggest sealed contacts, as
they are less likely to fail again. Make sure to get the correct
voltage ratings and at least the same current rating.

Regards,
Tim Schwartz
Bristol Electronics


wrote:

Hi. I have a NAD 2400 amp. It intermittantly drops into protect, may
take a
minute or a day. Reset power, works fine, again maybe quick or slow. I
have
checked over components for shorts, out of values, etc. I did replace
one
shorted gen purpose small diode.

When I got the amp, right end side of heat sink ran near cold, while
left
end side ran at a health feeling warmth. I looked at bias adjusts, which
were way off from each other. Experimentally, I set left to match right,
would kick off very quickly, so I set each the same, ran them both CCW
an
eigth of a turn at a time, going longer between kickoffs on average, and
both sides run a healthy feeling temp. Both are at about one third
setting
from full left on the pot.

As guessed I have no print for this, it was donated to me as a playtoy.
I
have checked L&R side components for values, etc, with nothing obviously
way
out of whack.

Now, the sound is perfect when running, could not be clearer, so audible
distortion isn't a problem.

Any ideas?

Cheers, Danny