Sharp SG-315H - FM STEREO AND POWER TRANSISTOR ADJUSTMENTS; FM Stereo Alignment; Power Transistor Bias Current Adjustment

FM STEREO ALIGNMENT
STEREO SIGNAL GENERATOR
PROCEDURE TUNING
NUMBER
FREQUENCY
CONNECTION nee
FREQUENCY
FUNCTION
SETTING
METER
CONNECTION ADJUSTMENT
REMARKS
FM-ANT 19 kHz
Terminal
98 MHz
Mod. level as
small as
possible
FM-ANT
Terminal
19 kHz 10%
Mod. 1 kHz
ch. L only
13.5% Mod.
Note:
(60 dB).
FM &
STEREO
(MONO: OFF)
Get the maximum
point. Repeat 2 or 3
times.
FM &
STEREO
(MONO: OFF)| (SO-505)
Across ch. R
Output Load.
L208
(Readjust)
Get the minimum
output point.
Output
level
of
FM
Signal
Generator
which
is
modulated
by
a
FM
Stereo
Signal
Generator
shall
be
1
mV
FM STEREO
SIGNAL
GENERATOR FM
ANT
FM STEREO
SIGNAL
GENERATOR
FM
ANT
MPX
DECODER
PRE, AUDIO,
ieee
AMPLIFIER
Figure 14 FM STEREO ALIGNMENT EQUIPMENT CONNECTIONS
BIAS
CURRENT
ADJUSTMENT
OF
THE
POWER
TRANSISTOR
(Refer
to
figure
15)
If
the
power
transistors
Q409
~
Q412
are
changed,
it
is
required
to
readjust
those
in
pair
so
that
they
will
operate
with
good
balance.
1) Have the variable resistor VR401 (VR402) being con-
nected
to
the
collector
of
Q403
(Q404)
placed
at
“minimum”
resistance
value
(fully
turn
it
counter-
clockwise).
2) Adjust the variable resistor VR401 (VR402) so that
the
voltage
between
the
test
point
TP401
(TP402)
and
the test point TP403 (TP404) becomes 9.5mV.
11
TP403
(TP404)
Q409 (Q410)
Figure 15
TP401 (TP402)
Figure 16 TUNER ALIGNMENT POINTS
SPRING WASHER
XWSSZ30 -06000
&x NUT
@ XNEZD30 -24000
8)
BUSHING
PSPANOOSIAFZZ
HEAT SINK
PRDAROII2 AFFW
HEAT SINK
SCREW
INSULATOR
oe
|
|
PSPAZ9002AGZZ
TRANSISTOR
VS28D234-Y/-3
SCREW
XBPSD30P10000
SPRING WASHER
TRANSISTOR BUSHING
SILICONE
GREASE INSULATOR
Figure 17 POWER TRANSISTOR REPLACEMENT
12