Sansui AU-7700 Service Manual page 5

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