Adjustment; Fm/Am Tuner Adjustment Procedures; High Frequency; Descriminator, Distortion And Signal Gain - JVC R-X40 Service Manual

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5.
Adiustment
Procedures
5-(1)
FM/AM
(MW/LW)
Tuner
Adjustment
Procedures
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Fig.8
FM Section
Band Cover
1.
Set
the frequency display
to
108.0
MHz.
2.
Connect
a DC.
VTVM. to test points
117 and GND.
3. Adjust
Ll03
so
that the VTVM.
shows
8.00V.
4.
And
set
the frequency display
to
87.5 MHz.
5.
Check the
VTVM.
voltage
reading
1.60
V
t
0.5 V.
Note: After
adjustment,
confirm that the
band cover
is
as
follows: (for
West
Germany only)
FM:
Low-end 87.5
MHz
- 300 kHz
Hish-end 108.0 MHz +500 kHz
Sensitivity
Low
Frequency
1. Connect an RF generator
to
the
antenna terminals on
the rear panel
through
a
dummy
antenna.
2.
Set an
RF
generator to
90 MHz,
a
modulation
of
1
kHz
and a deviation
of
75 kHz
to provide
an
input of
2
1tY.
3.
Connect a
VTVM
and an oscilloscope
to
the
Rec.
out
jacks
on the
rear panel.
4.
Set
the frequency display
to
90 MHz.
5.
Adjust coils
L101
,
L1O2
to
maximize
the
output.
High
Frequency
6. Set the RF
generator
to
106 MHz, a modulation of
1 kHz
and
a
deviation
of
75 kHz
to
provide an
input
ot 2
1tY.
7.
Set
the Frequency Display
to
106 MHz.
8.
Adjust the
FM trimmers
C102
to
maximize the output.
9.
Repeat
these
high and low
frequencies
adjustment
alternately
until
maximum sensitivity
is
obtained.
Descriminator, Distortion
and Signal Gain
1.
Press
to FM position.
2.
Connect
an RF generator,
1 kHz
modulation and
a
75 kHz
deviation
to
the
antenna terminals on the
rear
panel through
a
dummy antenna.
3.
Connect
an
oscilloscope,
Distortion
Meter and VTVM
to the
Rec.
out
jacks
on the
rear panel.
4.
Set the RF generator
to 98
MHz, generator output to
minimize.
5.
Set
the Frequency Display
to
a
98
MHz.
6.
Connect a DC
VTVM
between TP1
1
1
and
1
12.
7. Adjust the core
indicated
arrow
A
of
T101
for
DC
VTVM
reading
of 0
(zero) mV.
8. And
set
the
RF
generator output
to
1
mV.
9.
Adjust the core indicated arrow
B
of
T101
so
thatthe
distortion
is
minimized.
Multiplex
and Stereo Separation
Multiplex
1.
Set the
stereo signal generator as follows: 400
Hz
modulation
frequency,
7.5
kHz
deviation
pilot,
67.5 kHz
main and sub carriers. Connect its output to
the RF generator.
2.
Connect
an RF
generator
to
the
antenna terminals
through
a
dummy
antenna.
3.
Connect
a
VTVM, an
oscilloscope and
a
distortion
meter
to the
Rec. out
jacks on
the rear panel.
4.
Set
the RF generator
to 98
MHz and
outputof
1 mV.
5.
Set
the frequency display
to
98 MHz.
6.
Connect
the frequency counter to
19
kHz Test Point
TP1
08.
7.
Switch
off
the
pilot
signal
of
stereo
modulator.
8. Adjust
R181 so
that the
frequency counter
indicates
19
kHz
(0
-
-50 Hz).
Stereo Separation
9.
Switch the selector of
stereo
modulator
to left
channel
modulation.
10.
Adjust R173 so that the output
of
minimized.
1
1. Switch the
selector
of
the
modulator
modulation.
right
channel
is
to
right
channel
12. Adjust
R173
so
that the left channel
is
minimized.
13.
Set R173
to
a
average,
if
the
separation
of
left
and
right
is
different.
Stereo
threshold
14. Adjust R143 so that STEREO indicator lights at
the
output of RF generator
10
pV.
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R.X4O
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R-X4OL
No.2603
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