NAD 402 User manual

AM/FM TUNER §
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TABLE OF CONTENTS
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Instrument Set-up ©
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SERVICE SAFETY PRECAUTIONS
4 Use exact replacement parts for critical locations, marked J/\" on parts list.
2. Return lead dress to original position, and re-install protective covers.
3. Before returning to customer, test for shock hazard; use either method A or B:
A. Leakage test, "cold":
1. Unplug AC cord, turn power switch ON.
2. Connect one lead of High Voltage Insulation Tester to both prongs of AC plug.
3. Touch other lead to all exposed metal parts.
4. Impedance measurement must be 0.3 - 5.0 Megohms.
B. Leakage test, "live":
1. Plug unit directly into AC outlet; do not use isolation transformer.
2. Connect one lead of Leakage Current Tester to earth ground.
3. Touch other lead to all exposed metal parts.
4. Leakage measurement must be less than 0.5 milliamps.

SPECIFICATIONS
Specifications
are
measured
in
accordance
with
ANSI-IEEE
Standard
185
(1975),
i.e.
IHF
T-200
for
tuners.
FM TUNER SECTION
50dB quieting
60dB quieting
Capture ratio (45dBf)
IF rejection
Image rejection
AM suppression
Selectivity, alternate channel
Channel separation (1kHz)
Usable
sensitivity
(Q8MHZ,
75
ONMS)
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AH=
1.5uV
C=
2.0uV
Mono= 2.5uV
Stereo= 30.0uV
Mono, AH= 7.0uV
C= 9.0uV
Stereo=100.0uV
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AH=
2.0dB
C= 4.5dB
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AH=
60dB
C= 78dB
Subcarrier
suppression
(19kKHZ
and
38KHZ)
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Mono,
1kHz,100%
mod.,
AH=
0.20
%
50%
mod.,
C=
0.20
%
Stereo
L-R,
1kHz,100%
mod.,
AH=
0.12%
50% mod., = 0.30%
Stereo
L+R,
1kKHz,100%
mod.,
AH=
0.20
%
50% mod., C= 0.20%
Signal/Noise
ratio
(65dBf
IHF
wtd)
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Mono=
73dB
Stereo=
70dB
Frequency
response
(30HZ-15KHZ)
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C= 40dB
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3.2
-
6.3uV
Center tune sensitivity
Stereo indicator
Autosearch sensitivity
On @ 5.6 - 8.9uV
Off @ 4.5 - 74uV
6.3 - 17.8uV

AM TUNER SECTION
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Signal/Noise ratio (1MV iNpUt) 2.2... cere cree errr n Er re errr sada eee e eee a nee eeeee naan e rated 45dB
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Autosearch Sensitivity 2.0.0.0... eee cee ee cece eer tre rere nett te aa eee eee ena neeeeeaeeenae es 28.2 - 141.2uV
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PHYSICAL
Dimensions (Width x Height x Depth) «2.0.00. eee e err ee ete t ean eeeee ten eee tein 420 x 76 x 295mm
NEU WEIGHT o5 sce cov socket cteneds beast pce cte in actheate ava ads eee ee eee R: 3.6 kgs(8 Ibs)
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Power consumption at 120 or 230VAC, 50/60HZ ..........000 cece cece eet ectteeeeeeesa nea eeeeerens 15W

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ALIGNMENT PROCEDURE
NOTE:
1.
To
change
AM
steps
from
9kHz
to
10kHz
and
vice
versa,
press
the
MODE
and
SCAN
UP
buttons
simultaneously
for
three
seconds.
2. To reset the presets, press the AM FM and STORE buttons simultaneously for three seconds.
FM SECTION
A. PREPARATION
1. Set stereo modulator to mono mode with 1kHz modulating signal unless otherwise stated.
2. Set signal generator to FM mode with 75kHz deviation.
3. Store the following frequencies: 98MHz, 87.5MHz, 108MHz, 90MHz, and 106MHz.
4. Note: RF levels are open circuit voltages of signal generator with 75 ohms output impedance.
B. OSCILLATOR TUNING VOLTAGE
1. Connect DVM between TP6 and ground.
2. Tune to 87.5MHz and check DVM for a reading of 3VDC +0.5V.
3. Tune to 108MHz and check DVM for a reading of 20.5VDC +0.5V.
if either of the above is out of tolerance, adjust FE4 (oscillator coil) until both readings are
within tolerance.
Connect DVM between TP4 (VA) and TP5 (VB).
Apply 10.7MHz (90dBu) via 1Kohm resistor to TP7.
Adjust L8 for OVDC +50mV reading on DVM.
Adjust L9 until minimum THD is achieved at audio output.
Repeat (3) and (4) until no further improvement can be made.
akwONaE
When
adjusting
L9,
two
nulls
can
be
found.
With
the
core
on
top,
adjust
until
the
second
one
is
found
as
this
has
lower
THD.
Correct
position
of
the
core
is
normally
just
above
the
metal
casing.
D. SYNTHESIZER 1|.F. TRACKING
Maintain connection of DVM but disconnect 10.7MHz tap at TP7.
Apply 98MHz (60dBu) to FM antenna input and tune to 98MHz.
Adjust C16 for OVDC +20mV reading on DVM.
Fine adjust L9 for minimum THD.
Repeat (3) and (4) until no further improvement can be made.
Oy Bs GOO)
E. FRONT-END LF.
1. Connect DVM between TP3 (level) and ground.
2. Turn R48A fully clockwise and R48 fully counterclockwise.
3. Apply 98MHz (12dBu) to antenna input.
4.
Carefully
adjust
FE5
to
obtain
minimum
reading
on
DVM.
There
should
only
be
one
minimum.
F. R.F.
1. Apply 98MHz (6dBu) to antenna input.
2. Check if THD is better than 3%. If not, proceed to (3).
3.
Adjust
FE1,
FE2,
and
FE3
by
squeezing
or
stretching
using
a
non-metallic
tool
until
THD
is
better
than 3%.
4. Check THD at 90OMHz and 106MHz with 7dBu input. If THD is more than 3% for both fre-
quencies, re-adjust until required THD is met.

G. AUTOSEARCH LEVEL
1.
Turn
R48
fully
clockwise
and
R48A
fully
counterclockwise.
Set
stereo
modulator
to
L=-R
mode
and
apply
98MHz
(18dBu)
to
antenna
input.
Adjust
R48
counterclockwise
until
center
tune
LED
lights
up.
OF ON
Check
if
autosearch
operation
is
«working
properly
at
antenna
input
level
of
28dBu.
Center
tune
LED
should
be
at
least
2dBu
higher
than
FM
stereo
LED.
H.
STEREO
SEPARATION
AND
PILOT
SUPPRESSION
1.
Modulate
L-only
at
98MHz
(60dBu)
and
adjust
R62
for
minimum
output
on
right
channel.
2.
Modulate
R-only
and
adiust
R62
for
minimum
output
on
left
channel.
3.
Repeat
(1)
and
(2)
until
readings
are
the
same
and
within
specification.
4.
Turn
off
modulating
signal
but
leave
pilot
tone.
5.
Adjust
FL401
and
FL402
for
minimum
output
on
left
and
right
channels,
respectively.
AM
SECTION
A.
PREPARATION
1.
Set
signal
generator
to
AM
mode
with
1kHz
at
30%
modulation.
2.
Connect
22pF
ceramic
capacitor
between
signal
generator
and
AM
antenna
input
terminal.
Capacitor
should
be
as
close
as
possible
to
antenna
input
terminal.
3.
Store
the
following
frequencies:
603/600kHz,
999/1000kHz,
and
1404/1400kHz.
B.
OSCILLATOR
TUNING
VOLTAGE
1.
Connect
DVM
between
TP6
and
ground.
2.
Tune
to
603/600kHz
and
adjust
L6
for
1.75VDC
+50mV
reading
on
DVM.
C.
LF.
1.
Apply
999/1000kHz
(45dBu)
to
antenna
input.
2.
Tune
to
999/1000kHz
and
adjust
L7
for
maximum
reading
on
audio
output.
D.
R.F.
1.
Apply
603/600kHz
(45dBu)
to
antenna
input.
2.
Tune
to
603/600kHz
and
adjust
L5
for
maximum
reading
on
audio
output.
3.
Apply
1404/1400kHz
(45dBu)
to
antenna
input.
4.
Tune
to
1404/1400kHz
adjust
C26
for
maximum
reading
on
audio
output.
5.
Repeat
(1)
to
(4)
until
no
further
improvement
can
be
made.
TPS
R62
FL402
FL401
(VB)
18
LO
C16
TP6
® e
s ise
RASS
LEA
TPS R48A RABEL? C26 TP4 i L6
(LEVEL) (vA)
TUNER ADJUSTMENT POINTS
5.
Increase
antenna
input
signal
to
22dBu
and
adjust
R48A
clockwise
until
FM
stereo
LED
lights
up.
]
;

INSTRUMENT SET-UP
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STEREO MODULATOR SIGNAL GENERATOR
DUMMY
ANTENNA
TUNER OUT ANTENNA
TERMINAL
UNIT UNDER TEST
OSCILLOSCOPE
IHF FILTER
OUTPUT—CONNECTED INSTRUMENTS

IC BLOCK DIAGRAMS
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LC7582
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256 Bytes RAM
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LM7000
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CAUTION: RePLAcE
WITH SAME TYPE FUSE
ATTENTION:
UTILISER UN FUSIBLE
DE RECHANGE OE MEME
TYPE
TUNER PCB
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