NAD 3240 - Amplifier Alignment Procedures; Main Amplifier Adjustment Steps; Preamp and Volume PCB Layout

ALIGNMENT
METHOD
MAIN
AMPLIFIER
ALIGNMENT
IMPORTANT
NOTES:
1)
Before
adjusting,
remove
input
signal
and
load,
and
set
Speaker
Impedance
switch
to 8
ohms.
(Reset
to 4
ohms
when
finished.)
2)
These
adjustments
are
always
necessary after
repair
to
main
amplifier.
3)
After
repair,
it is
recommended to
use
current
limiter
(40-80W
lightbulb)
in
series
with
AC
mains
line,
for
initial
turn-on.
A.
CENTER
VOLTAGE
ADJUSTMENT
1. Connect
DVM
across
L
channel
(R
channel)
output
terminals.
2. Turn
on,
and
adjust
VR-401
(VR-402)
for
reading
of
0V ±
30
mVDC.
B. IDLE
CURRENT
ADJUSTMENT
1. Remove
solder
short
across
R-471
and R-472.
2.
Connect
DVM
across
R-471.
3.
Turn
on
and
adjust
VR-403
for
reading
of 28
mV
± 2
mVDC.
4.
Repeat,
using
R-472,
adjust
VR-404.
C.
FINAL
ADJUSTMENT
.
.
1. Leave
power
on
minimum
5
minutes.
2.
Repeat
center
voltage
and
idle
current
adjustments.
3. When
finished,
replace
solder
short
across
R-471
and
R-472.
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233
AMPLIFIER
ALIGNMENT
POINT
PREAMP,
VOLUME
PCB
LAYOUT
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