NAD 4130 - Specification

DETECTOR
COARSE
ADJUSTMENT
(OPTIONAL,
NEEDED
ONLY
IF
DETECTOR
WAS
REPAIRED).
Reduce sweep
modulation
level
to
+/— 75
kHz
and set input level
to 300 yV.
Adjust
FM
generator
frequency
so
that
both
legs
of
the
inverted
U-shaped
curve:are
equally
high
on
the
dis-
play.
The
curve
should
be
almost
perfectly
symmetrical.
|
Disconnect
detectorprobe
from
tuner
and
oscilloscope.
Connect
either
of
the
tape
rec.
outputs
to
the
oscillo-
scope.
Adjust
IFT
1
primary
(closest
to
the
rear
of
unit)
to
maximum
sucvebiciane
and
IFT
1
secondary
(closest
to
the
front
of
unit)
to
minimum
curveheight
and
straightest
possible
line.
Go
back
and
forth
between
primary
and
secondary
till
both
are
peaked.
NOTE: Both the cores should be within 1.5 mm from the top of the form.
DETECTOR ALIGNMENTS (FINAL)
Disconnect
detectorprobe
and
connect
tape
rec.
outputs
to
VTVM’s,
oscilloscope
and
distortion
analyzer.
Switch
stereo
generator
to
1
kHz
100%
(+/—
75
kHz)
mono
modulation
and
oscilloscope
to
normal
internal
sweep
0.2
mS
and
0.5
V/cm
sensitivity.
Detector reference frequency
Reduce
FM
generator
output
level
while
monitoring
THD
from
left
channel.
When
THD
increases
to
3%,
fine
tune
the
FM
generator
frequency
to
minimum
THD.
Reduce
FM
generator
output
level
and
fine
tune
till
no
reduction
in
the
3%
THD
can
be
achieved
by
fine
tuning.
Use
this
frequency
for
all
the
following
detector,
MPX
and
DYN
SEP
adjustments.
NOTE:
The
typical
input
level
for
this
3%
THD
should
be
1.6
pV
to
2.3
yV.
This
|
is
done
only
to
“lineup”
the frequency from the generator to the tuner’s frequency.
If
IHF
usable
sensitivity
(—30
dB
ten
3.16%
THD+
N)
is
to
be
verified,
a
proper
!HF
band-
passfilter
must
be
used.
Connect
DMM
across
TP
2
(negative)
and
TP
1
(positive).
Set
FM
generator
output
level
to
1000
pV.
Adjust IFT 1 primary (closest to the rear of unit) forO Von DMM
TOLERANCE +/— 50 mV
Adjust IFT 1 secondary (closest to the front of unit) for lowest THD
SPECIFICATION _ less than 0.1%.
Repeat
steps
3
—
5
and
6
till
no
further
improvements.
Record
the
DMM's
final
reading
for
use.later
in
the
adjustment.
AUTOSEARCH LEVEL
Connect DMM between IC 2 pin 12 and ground.
Increase
FM
generator
level
upwards
from
0
and
adjust
VR
1
so
that
DMM
reading
goes
from
0
V
to
approxi-
mately
4.8
V
at
10
pV.
TOLERANCE +/—2 pV
STEREO DECODER, MPX FILTERS.
VCO
Connect a frequency counter between IC 6 pin 11 and ground.
Set FM generator to 1000 pV output and no modulation.
Adjust VR 3 for a 19000 Hz reading on the counter.
TOLERANCE +/— 100 Hz
Disconnect
frequency
counter
and
press
FM
NR
defeat
switch
(in).
Stereo switch threshold.
Modulate FM generator 1 kHz 45% left only plus 19 kHz pilot 8 — 10 %.
Increase
FM
generator
level
upwards
from
O
and
adjust
VR
2
so
that
stereo
light
turns
on
and
audio
outputs
as
watched
on
VTVM
and
oscilloscope,
switches
to
one
channel
only
at
10
pV
input
level.
TOLERANCE
+5
uV
NOTE:
When
turning
input
level
down
the
unit
will
switch
into
mono
at
a
lower
level,
typically
5
—
7
wV.