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9.
ADJUSTMENT
9.1
AM
SECTION
1.
Through a 1k ohm
resistor,
connect
an AM
signal
generator
to the
AM antenna
terminal.
Set for 40OHz
at 100dB
and 3O%
modulation.
2
Connect
AC
voltmeter
to TAPE
REC
iack
(L
or
R).
Set
FUNCTION
switch
to AM
position.
Set AM signal
generator
and SX-450
dial in-
dication
to
point
A
(600kHz).
Adjust
T6 for
maximum
indication
on
AC
voltmeter.
Set AM
signal
generator
and
SX-450
dial in-
dication
to
point
C
(1,400kH2).
4.
sx-450
7. Adjust TC4 for maximum
indication
on AC
voltmeter.
8.
Again
set
AM signal
generator
and
SX-450 dial
indication
to
point
A.
9.
Adjust bar
antenna core for
maximum in-
dication
on AC voltmeter.
10.
Return AM signal
generator
and
SX-450 dial
indication
to
point
C.
11. Adjust
TC5
for
maximum
indication
on AC
voltmeter.
12.
Repeat steps
4-11 to
eliminate variations in
AC voltmeter indications
at
noint
A and
C.
F
q'
.{
)
5.
c).
1
AC
voltmeter
AM
signal
generator
tr@
q
25
9.2 FM
SECTION
1. Through
300 ohm
dummy
antenna, connect
FM signal
generator
to the 300
ohm FM
antenna
terminals
and set for 4OOHz
at
100dB
and
IO0%
modulation.
2.
Connect
AC voltmeter
and distortion
meter
to
TAPE REC
jack
(L
or
R).
3.
Set
FUNCTION
switch
to
FM
and MUTING
switch
to OFF.
4.
Set
FM
signal
generator
and
SX-450 dial
indication
to
point
A
(90MHz).
5.
Adjust T3 for
maximum indication
on
AC
voltmeter.
6. Adjust
T5
lower
core for
center
of scale
indication
on AM/FM meter.
7. Set
FM
signal
generator
for
9dB output
and
adjust
T1
and
T2 for maximum
indication
on
AC
voltmeter.
8.
Set
FM
signal
generator
and
SX-450 dial
indication
to
point
C
(106MHz).
9. Adjust
TC3, then
TC1
and TC2 for
*u"i*rr-
A |
/
indication
on AC voltmeter.
10.
Again set FM
signal
generator
and SX-450
dial
indication
to
point
A.
11.
Adjust
T3, then
T1 and
T2
for
maximum
indication
on
AC voltmeter.
12. Repeat
steps 8-11
to eliminate
variations
in
sensitivity
at
points
A and C.
13. Adjust
"t4
for maximum
sensitivity.
14. Detune
to noise
only
and adjust
T5 lower
core
for center
of scale
indication
on FM
meter.
15.
Set SX-450
dial indication
to
point
B
(98MHz)
and
adjust FM
signal
generator
for
center
of
scale indication
on
AM/FM
meter.
16.
Set FM
signal
generator
output
to 60dB
and
adjust T5 upper
core for
minimum
distortion.
17.
Repeat steps
14-16
eliminate
variation in
mini-
J"
'a
mum
distortion
position.
tl
ACvoltmeter
Distortion
0*-
f'{
T2
T1
TC1
l\\
t
FI
a)
FM
signal
generator
tr@
9.3
MPX
SECTION
1. Through 300 ohm
dummy antenna,
connect
FM signal
generator
to 300 ohm FM
antenna
terminals.
2.
Connect multiplex
signal
generator
to extemal
modulation
terminals
of
FM
signal
generator.
3. Connect oscilloscope
horizontal input
to
MPX
signal
pilot
output
and
vertical
input via
probe
to TP
(No.
13) of circuit board.
sx-450
4.
Set SX-450 dial
indication
to 98MHz
and adjust
FM signal
generator
for center
of scale indi-
cation
on AM/FM
meter.
5. With
FM
signal
generator
unmodulated,
adjust
VR1 so that lissajous
pattern
on oscilloscope
becomes
stationary
as shown
in Fig. 12.
6.
With MPX signal
generator
modulation lkHz,
L
+
R
67.5kHz
deviation and
pilot
7.5kHz
deviation,
adjust T4 for minimum distortion.
tl'
'a
t
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r|}
l'
I
I
I
I
I
I
I
I
I
i
AC voltmeter
Distortion
meter
FM
signal
generator
Dummy load
Oscilloscope
MPX
signal
generator
Fig.12
9.4 POWER
AMPLIFIER
SECTION
(IDLE
CURRENT}
1. Set
BASS
and TREBLE controls
ro center
a r''
position.
2. Nothing
should
be connected
to the
INPUT
jacks
of
SX-450 and
an 8
ohm dummy
load
should
be connected
across the
SPEAKER
terminal.
3.
A DC
voltmeter
should
be
connect
across
between
terminal
number
19
1+;,
20
(-)
for
Left
channel
and
18
1+1,
l7
(-)
for
Right
channel.
4.
Cut the
jumper
lead,
if the
voltage
less
than
15mV.
fi
j**'
ita
{
fNt
#
DC Voltmeter
ed
)10.
DrAL
CORD STRTNGTNG
Remove
the Front
panel
(See
page
14, 15).
1. Turn
tuning drum
fully clockwise
(as
viewed
from X direction
in
Fig. 13).
2. Tie one end
of cord to stud on
inner section of
tuning drum
(more
easily
performed
by loosen-
ing
setscrew and temporarily
removing tuning
drum
from shaft).
3. Pass cord through
pulley
opening,
make
a
half
tum around
the
pulley,
then
route in the
sequence:
pulley
A-Dial
needle-pulley B-C.
4. Wind
cord clockwise
(as
viewed from rear
panel)
3
turns around dial
shaft, then route to
pulley
D.
5. Wind 3 tums around
dial
pulley
and tie
to spring
so that the
cord is under tention.
1
6. Turn TUNING
knob and confirm
normal cord-
motion. then trim
off excess
cord.
I
t
7. With tuning
capacitorblades
fully closed, move
'
dial
needle to
starting
point
(left
edge
of
scale).
8.
Apply
laquor to tied
ends of cord.
Spring
hook
Tie to spring hook
sx-450
DIAL NEEDLE INSTALLATION CAUTION
Metal
portion
of
dial
pointer
is
plated.
If this
section is
touched directly by
hand
or
fingerprints
and other
impurities, it is
difficult to
remove
dirt
from
aventurine
finish.
As this
is not
desirable
in terms of
both appearance and anti-
corrosion, take exteme care not to touch the
metal
section when
handling
the dial
needle.
Dial needle
..'
\ -'
'rl
,.'l
I
I
Pulley
C
End:
Stud
Start:
Fasten
on end of
the
cord to start
Fis.13
Pulley
D
Tuning
drum
Dial
shaft
29
-
1
-
2
-
3
-
4
-
5
-
6
-
7
-
8
-
9
-
10
-
11
-
12
