Sharp GF-9000H - Page 10

For the radio
Caution:
(high frequency) circuit, refer to “GENERAL
ALIGNMENT INSTRUCITON” in the GF-777H Service Manual
ELECTRICAL ADJUSTMENT
e Record Amplifier Bias Current Adjustment and Bias
Oscillator Frequency Check
1) Make connection of instruments as shown in Fig.14—1.
2) Set the mode selector switch at ‘‘tape”, the tape selector
switch at ‘‘normal’, the beat cancel switch at “A” and
the record level control knob at 10 (max.)’’ position.
3) Place the unit in record mode. Adjust the coil (L203 or
L204) so that the electronic voltmeter reads 45mV:
with the tape selector switch at “metal” position, also
adjust so that the reading is 88 + 3mvV.
4) Check that the frequency counter reading available then
is 86 + 3kHz. If not, adjust the bias oscillator coil (L205)
and readjust the bias current in step 3) above.
(See to Table 14—1.)
e Erase Current Check
1) Make connection of instruments as shown in Fig.14—2.
2) Set the tape selector switch at ‘‘metal” position.
3) Place the unit in record mode, and see that the electronic
voltmeter reading is 120 + 40 mV.
With the tape selector switch changed to ‘‘normal”’ position,
see that the electronic voltmeter reading is 60 + 20 mV.
e VU Meter Sensitivity Adjustment
1)
Make
connection
of
instruments
as
shown
in
Fig.14—3.
2)
Short
pins
and
@)
of
the
CNP202
to
cause
a
stop
of
the
oscillation.
3) Set the mode selector switch at “tape’’, the record mode
selector switch at ‘‘manual’”’ and the Dolby NR switch
at “off” position.
4)
From
the
audio
generator,
apply
a
signal
of
oscillation
frequency
1 kHz.
5)
Place
the
unit
in
record
mode,
and
adjust
the
record
level
control
knob
so
that
the
electronic
voltmeter
reads
580
mV.
6}
Adjust
the
semi-variable
resistor
(VR351
or
VR352)
so
that
the
VU
meter
indicates
“+3
VU”
(D0).
R207 or R208 recctalmeveack oscilloscope
sre
electronic frequency
voltmeter counter
Figure 14—1
Beat Cancel Switch Oscillation Frequency
86 + 3kHz
89
81
Table 14—1
record mode erase head oscilloscope
electronic
voltmeter
Figure 14—2
record/playback
cide
ial
eu
external
mic
Den
‘
_
jack
a
a
electronic
oscilloscope
03,48
in
(Rec
2°8
2
J303
(L-ch)
Fenatd
voltmeter
audio generator J304 (R-ch) mode
attenuator
$0301
@) Pin (GND)
Figure 14—3
—14—