NAD 7130 Service Manual

FM
ALIGNMENTS
NECESSARY
INSTRUMENTATION
FM
GENERATOR
(less than
0.05%
THD)
STEREO
GENERATOR {less
than
0.05%
THD,
more
than
50 dB
separation
at
1 kHz.
AUDIO
GENERATOR
(not
necessary if FM
generator
has built
in
sweep;
i.e.
SOUND
TECHNOLOGY
ST
1000A
and
ST
1020
A)
2
AC
VTVM's
(or
one
with
left/right
channel switch)
THD
ANALYZER
(resolution
better
than
0.1%)
OSCILLOSCOPE
(5mV
or better
sensitivity, X
input
capability)
FREQUENCY
COUNTER
VOM or
DMM
(high
impedance,
must read in
mV)
DIODE
DETECTOR
PROBE
COPPER
/
FERRITE INDUCTOR
IMPORTANT
While
ail
FM generator
output
levels
hereafter
are
referred
to the
300
ohm
input,
75 ohm
input
can
be
used, but
be aware of
possible
equipment
groundloops
and
divide
the
RF output
level
by
2.
Before
alignments
commence
set
input
selector
to
tuner
and
release
tape,
mono
and
dynsep
defeat
switches
(out)
ALIGNMENT
OF
FRONTEND
should
only
be
necessary
after
repair
to frontend
or
crystal
oscillator
circuits (pin
2
and
3
on
1C7)
A
TUNING
VOLTAGE
(OSCILLATOR)
It
is
essential
to check
tuning
voltage before
aligning
the
rest
of
the
frontend.
1.
Connect
DMM between
shield
and
pin 6 on
frontend.
2.
Tune
to
108
MHz
and
adjust
L
707 if
voltage
Is
incorrect.
SPECIFICATION
20.5V ±0.5V
3.
Tune
to 87.5
M
Hz and
read
voltage,
repeat
step
2
and
3
if
incorrect.
SPECIFICATION
3V
±
0.5V
B.
READJUSTMENT
(TRACKING)
1.
Connect
RF
generator
to antenna
input and
detectorprobe
to
pin
1,IC2 (IF
DETECTOR).
with
ground
to
detectorshield.
Adjust
sensitivity
of
oscilloscope
to maximum
(5mV
or
better)
and modulate
FM
generator
sweep
±
300
kHz
or
more
WITH
modulating
(sweep)
signal connected
to X-imput of
oscilloscope.
2.
Set
tuner
to 90 MHz,
enter
into
preset
1,
and
tune
generator
so that
curve
appears
on
oscilloscope.
Turn
down
RF
Input level
so that curve
covers
approximately
1/2 of
oscilloscope
display.
3.
Check
alignments
of
L
702
-
L
704
-
L705 by
inserting
copper/ferrite
Inductor
close
to
them while
walching
curve
on
oscilloscope.
Curve should
decrease
in
height
with
either
ferrite
(same as Increasing
Inductance,
i.e.
more
core) or with
copper
(same
as
decreasing
inductance,
i.e.
extend
size
of
coil).
If
curve
increases
ii
size
more
than
10%,
adjust
only
the coil which
reacts
incorrectly.
Adjust
coils
by
gently
extend
or contract
the
aircoil
with
a non-metallic
and
non-static
tool
(i.e.
plastic
knit-pin
or
a wooden
stick).
Be
careful
rot
to
deform
coil.
4.
Set
tuner to
105MHz, enter
into
preset
2,
and
tune
generator
so
that curve
appears
on
oscilloscope.
5.
Check
L
702
—
L 704
—
L 705 again
with
the
ferrite/copper
inductor.
Curve
should
not
increase
mor^than
10%
on any
of the coils.
6.
Repeat
step 2
+
3
+
4+
5if
curve height
is
outside of
telerances,
if
necessary
distribute
the error
between
90
and
105 MHz.
Check
tuning
voltage
again
if
tolerances not
possible
to
achieve.
C.
IF
ADJUSTMENT
1.
Set
tuner
to
approximately
98 MHz
(the
tuner
must
be
tuned
to
an
unoccupied
frequency)
enter into
p-^set
3,
and
tune
FM
generator
to display
a
curve
on
the
oscilloscope.
2.
Adjust
L
709
(IFT tuner
frontend) to
maximum
and
symmetrical
curve
on
the display,
using
as
little
h
put
signal
as possible.
-
6
-

NAD 7130 Specifications

General

Brand	NAD
Model	7130
Category	Stereo Receiver
Language	English