Sanyo JA20 - Front Panel Disassembly; LED Meter PCB Assembly; Adjustment Procedures; Bias Adjustment

FRONT PANEL DISASSEMBLY
FITTING
OF
LED
METER
PCB
ASS'Y
ADJUSTMENT
1. ADJUSTMENT OF BIAS
* CONDITIONS
2.
ADJUSTMENT
OF
PEAK
LEVEL
METER
*
CONDITIONS
VOLUME
CONTROL:
“0”
(Minimum)
BALANCE
CONTROL
VOLUME:
(Center)
BASS
CONTROL
VOLUME:
“0”
(Center)
TREBLE
CONTROL
VOLUME:
“0”
(Center)
FUNCTION
SWITCH:
TUNER
MONITOR SWITCH: SOURCE
HIGH FILTER SWITCH: OFF
LOUDNESS SWITCH: OFF
OUTPUT LOAD: NO LOAD
After
the
power
switch
is
turned
on,
adjust
SVR703
and
SVR803
respectively
as follows:
L — channel: SVR703 for 2 ~ 3mV reading between the
both leads of R734.
R
—
channel:
SV
R803
for
2
~
3mV
reading
between
the
both leads of R834.
TEST OSCILLATOR
(OSCILLATOR & ATTENUATOR)
INPUT
SIGNAL:
1kHz,
46mV
OUTPUT
LOAD:
8Q,
100W,
non-inductive
resistance
VOLUME
CONTROL:
"10"
(Maximum)
(1)
Introduce
test
oscillator
signal
to
the
TUNER
terminal.
(2)
Adjust
test
oscillator
signal
so
that
LED
“3”
of
the
right
side
peak
level
meter
begins
to
light.
(The
output
voltage
of
the
right
side
becomes
about
3.5V
at
this
time.)
Next,
check
that
the
output
voltage
of
left
speaker
is
same
as
the
right
side.
Adjust
with
SVR762
so
that
LED
“3”
of
peak
level
meter
begins
to
light.
(3
—
OSCILLOSCOPE
OUTPUT (SP)