Sansui AU-7700 - ADJUSTMENT PROCEDURES; Driver Circuit Board Adjustment

3.
ADJUSTMENT
3-'l . Driver
Circuit
Board
Adirstment
Note:
1.
Conf
irm
the
AC
power
supply voltage.
2.
MASTER
VOLUME ...
...Minimum
3.
SPEAKERS
Selector...
...A
4.
Make
the
SP
terminals
free
(no
load).
(See
tig.
3-1
,
3-2
and 3-3)
5. For adjustment,
run
the unit
for
more
than
3
minutes
after
the
power
is
switched
ON.
6. Room
temperature
should
be 1B-2B.C
(65-83'F)
for
bias
current
adjustment.
STEP
SUB'ECT
EQUIPMENT
MEASURE
OUTPUT
ADIUST
ADIUST
FOR
CONDITION
1
I
DC
0V
L-ch
i
OC volr
merer
I
Sp terminal
L-ch
I I |
{s""
Fis.
3-3)
2
I
oC
0V
R-ch
I
Sume as
above
I
sp
rerm
inat
R-ch
I I I
(see
Fig.
3-3)
The
unit
installing
quick
acting
fuses
3-1
i
P'l:
currenr
I
,a
miiliammeter
I
Ir-cn I I
4-1
igiurcurrent
lSameasabove
I
j
n-crr
i
i
XThe
unit not
installing
quick
acting
fuses
3'2
I
f::i
curren,
I
DC
m ittiam
merer
i
F-2097
F-2097
t02
Between
a red
wire
&
plus
side of
C602
on
F-2416
(See
Fig.
3-2)
Between
other red
wire
&
plus
side of
C602
on
F-2416
(See
Fig.
3-2)
F01
4-2
|
Bias
current
I
Same
as above
ln-.n I
F-2097
VROl
t-2097
VRO2
t-2097
VRO3
t-2097
VRO4
t-2097
VRO3
t-2097
VRO4
0V
+10mV
Same as
above
45
+
10mA
Same as above
45
+'10mA
Same as above
oïurn
volumes
of
VR03, VR04
CCW
.Step
down
meter's
range
accord
ingly
"Step
down
meter's
range
accordingly
:ii
Bias
current
adjustment
on
the unit not
installing
quick
acting
fuses.
t)
Disconnect
a
red
wire
(plus
side) from
C6OZ on
F-2416
which
goes
to
driver
&
power
supply
circuit
board,
F-2097,
then
con-
g)
flrm
that collector
voltage
+41V
of
power
transistor,
TR23
(L-:h)
or TR24
(R-ch)
on F-2097
is not
supplied.
F ig.
3-'l
Fig.
3-2
Adjust
vR03
(L-ch)
or
vR04
(R-ch)
so
that
bias
current on
one
channel
at
the disconnected
points
between
A
and
B
(see
Fie.
3-2)
is
45
+
10mA.
After
connecting
the
red
wire
again,
adjust
it
on
another
channel
as same
as steps
1)
and 2).
2)
v
(L)
(R)
F-2097
SPEAKER TERMINAL
volt
meter
O
lliammeterQ
milliammeter@
4