Akai AS-8100 User manual


%
TABLE
OF
CONTENTS
SPECIFICATIONS.
.......0..:ccceeceeee
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tere
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ereen
ees
I.
DISMANTLING
OF
AMPLIFIERS
............-:.20::seeeeee
DISPOSITION
OF
P.C.
BOARD
I.
Il.
AS
WELL
AS
CONDENSER
OUTPUT
............0:205
TUNER
SECTION
ADJUSTMENT
.............:::cceeeeees
V.
V..
I
0
1
MAIN
AMPLIFIER
ADJUSTMENT
.................00
EPC
(ELECTRONIC
PROTECTION
VI.
CIRCUIT)
ADJUSTMENT
..........ccccceceeeee
erent
etee
ees
DISPOSITION
OF
EACH
ADJUSTMENT
kes
12
14
COMPOSITE
VIEWS
OF
COMPONENTS
..............-+5+
VI.
Vill.
When
placing
order
for
parts,
please
use
separate
PARTS
LIST.

1.
SPECIFICATIONS
An
asterisk
next
to
a
figure,
indicates
the
minimum
guaranteed
performance.
AMPLIFIER
SECTION
OUTPUT
MUSIC
POWER
OUTPUT
30
W
each
channel]
at
8
2,
4-channel
60
W
each
channel
at
8
2,
2-channel
RATED
POWER
OUTPUT
18
W
each
channel
at
8
2,
4-channel
40
W
each
channel
at
8
2,
2-channel
REC.
OUTPUT
Din:
25
mV
Pin:
150
mV
INPUT
SENSITIVITY
Phono:
3mV
AUx.:
150
mV
Tape
1,2:
150mV
FREQUENCY
RESPONSE
20
to
100,000
Hz
+
0/-3
dB
at
8
2
(20
to
50,000
Hz
+0/-1
dB
at
8
2*)
POWER
BAND
WIDTH
20
to
30,000
Hz
at
8
2
HARMONIC
DISTORTION
Less
than
0.1%
at
8
2
HUM
AND
NOISE
-48
dBm
SIGNAL
TO
NOISE
RATIO
Phono:
70
dB
(65
dB*)
Aux.:
80
dB
(75
dB*)
Tape:
80
dB
(75
dB*)
TONE
CONTROL
Base:
+10
dB
at
100
Hz
Treble:
+10
dB
at
10,000
Hz
LOUDNESS
CONTROL
+7
£2
dB
at
100
Hz
+4
+2
dB
at
10,000
Hz
FILTERS
High
Cut
Filter:
-9
£2
dB
at
50
Hz
-6
+2
dB
at
10,000
Hz
FM
TUNER
SECTION
FREQUENCY
RANGE
75
to
91
MHz
£800
KHz
(JAPAN)
87
to
109
MHZ
+800
KHz
(U.S.A.
and
S.
AFRICA)
IF
FREQUENCY
10.7
MHz
SENSITIVITY
Less
than
10
dB
HARMONIC
DISTORTION
Mono:
Less
than
0.5%
Stereo:
Less
than
0.8%
(1.0%*)
SIGNAL
TO
NOISE
RATIO
Better
than
60
dB
SELECTIVITY
Better
than
60
dB
(40
dB*)
IMAGE
INTERFERENCE
RATIO
Better
than
100
dB
(80
dB*)
IF
INTERFERENCE
RATIO
Better
than
100
dB
(90
dB*)
CAPTURE
RATIO
Better
than
1.5
dB
(2
dB*)
SPURIOUS
RATIO
Better
than
34
dB
MUTING
SENSITIVITY
20
+3
dB
SCA
INTERFERENCE
RATIO
Better
than
50
dB
SEPARATION
Better
than
35
dB
ANTENNA
INPUT
IMPEDANCE
300
2
balanced;
752
unbalanced
AM
TUNER
SECTION
FREQUENCY
RANGE
525
£5
KHz
to
1630
+15
KHz
IF
FREQUENCY
455
KHz
SENSITIVITY
Dummy:
Less
than
15
dB
Loop:
Less
than
46
dB
HARMONIC
DISTORTION
Less
than
1.5%
SIGNAL
TO
NOISE
RATIO
Better
than
50
dB
(40
dB*)
SELECTIVITY
30
dB
(20
dB*)
IMAGE
INTERFERENCE
RATIO
Better
than
70
dB
IF
INTERFERENCE
RATIO
Better
than
70
dB
TRANSISTORS
USED
4
.....2SA545
(M)
2
.....28C535
5
.....28C838
(H)
8
.....28C853
(M)
12.....2SC900
(F,
H)
3
.....28C945
(R)
1
.....28C968
(3)
2
.....28C1014
(D1,
D2)
8
.....28D313
1
.....SE3001
FET
USED:
1.....28K30
IC
USED:
2....LALI11
6.....LD3120
1.....A3300
DIODES
USED
6
.....IN34A
4
.....1N60
8.....10D1
1.....5B2
1....1RCS
Fees
1S337A
4....VD1211
THERMISTORS
USED:
4.....23D29
POWER
SUPPLY
100
V
to
240
V
AC,
50/60
Hz
U.S.A.:
117
V
AC,
60
Hz
as
per
U/L
POWER
CONSUMPTION
200
W
DIMENSIONS
487(W)
X
165(H)
X
346(D)
mm
(19%"
X
7"
X
14%")
WEIGHT
16
kg.
(35.3
lbs.)

ll.
DISMANTLING
OF
AMPLIFIERS
In
case
of
trouble,
etc.
necessitating
disassembly,
please
disassemble
in
the
order
shown
in
photographs.
Reassemble
in
reverse
order.
UPPER
COVER
LOWER
COVER

i.
DISPOSITION
OF
P.C.
BOARD
AS
WELL
AS
CONDENSER
OUTPUT
EQUALIZER
AMP.
oy
op
‘
mon
|
P.C.
BOARD
—.
‘
‘
coat
AM
IF
AMP.
P.C.
BOARD
MPX
AMP.
P.C.
BOARD
:
2a:
FRONT
END
:
awe
ns
(TUNER)
FM
IF
AMP.
:
bya
:
oe
P.C.
BOARD
i).
es
:
MAIN
AVE
P.C.
BOARD
a
POWER
TRANSFORMER
POWER
TRANSFORMER
PHASE
INVERTER
POWER
SUPPLY
AMP.
P.C.
BOARD
P.C.
BOARD
TONE
CONTROL
AMP.
P.C.
BOARD
VOLUME
CONTROL
P.C.
BOARD

IV.
TUNER
SECTION
ADJUSTMENT
1.
TERMINATION
PAD
(MODEL
2151-8)
FM
IF
CIRCUIT
ADJUSTMENTS
(See
Figs.
1
and
2)
FM
IF
PC.
BOARD
2).
3)
4)
5)
AM-FM
RADIO
IF
GENESCOPE
(MODEL
MSW~721C)
Fig.
1
10.7
MHz
Fig.
2
Adjust
V-Gain
Volume
to
obtain
a
2
cm
amplitude
of
0.3V
p-p
AM
FM
Radio
IF
Genescope
cali-
bration
voltage
on
screen
and
set
Genescope
Cutput
to
50
dB.
Connect
Genescope
Output
to
point
(1)
(FM
IF
Input),
and
Genescope
Input
to
point
(8)
(AF
Output).
Set
Mode
Switch
to
“FM”
and
set
dial
to
about
109
MHz
reception
frequency.
Adjust
the
upper
core
of
IFT
“L,”
of
FM
IF
Amp.
P.C.
Board
so
that
the
S
Curve
output
voltage
is
maximum.
Also
adjust
the
lower
core
to
obtain
optimum
S
Curve
linearity.
In
making
this
adjustment,
in
some
cases
the
rank
of
the
ceramic
filter
causes
a
discrepancy
in
the
S
Curve
Marker
Point,
but
it
is
satisfactory
if
through
adjustment
a
margin
of
within
+500
Hz
can
be
obtained
(See
Fig.
3).
Ceramic
Filter
Rank
Center
Frequency
|
Error
Tolerance
10.60
MHz
10.65
MHz
10.70
MHz
10.75
MHz
10.80
MHz
as
2)
3)
4)
COLOR
MARK
CERAMIC
FILTER
Fig.
3
FRONT
END
AND
FM
IF
MATCHING
ADJUSTMENT
(See
Fig.
6)
IF
COIL
(Front
end)
Fig.
4
Fig.
5
Adjust
V-Gain
Volume
to
obtain
a
2
cm
amplitude
of
0.3V
p-p
AM
FM
Radio
IF
Genescope
cali-
bration
voltage
on
screen,
and
set
Genescope
Output
to
90
dB.
Connect
Genescope
Output
to
3002
impedance
FM
Antenna
Terminal,
and
Genescope
Input
to
Terminal
(8)
(AF
Output)
of
FM
IF
P.C.
Board.
Set
Mode
Switch
to
“FM”
and
set
the
tuning
indicator
to
the
right
end
of
the
dial.
Adjust
the
upper
core
of
IF
Adjustment
Core
in
front
end
so
that
the
value
of
the
S
Curve
wave
height
is
maximum.
Then
adjust
the
lower
core
so
that
the
noise
element
is
maximum
and
the
upper
and
lower
reaches
of
the
scanning
line
are
the
same
level
(See
Figs.
4,
5
and
7).

3.
1)
2)
AS-8100
TERMINATION
PAD
bY
LA]
INPUT
OUTPUT
(MODEL
2151-8)
<<.
_
~
AM-FM
RADIO
IF
GENESCOPE
(MODEL
MSW-72IC)
Fig.
6
©
66
66
AM
AM
AM
tS
=
jae
LO
IF
-LR2
LRI
LA
(
TOP
VIEW
OF
FRONT
END
Fig.
7
AS-8100
-_
+O,
nomen
ye)
OUTPUT
30020
LCH
:
INPUT
O-—
—~
SPEAKER
~+——-O
FM
ANTENNA
OUTPUT
80
45W
TERMINATION
PAD
INEUT
(MODEL
MR-200)
FM
SIGNAL
GENERATOR
DISTORTION
METER
(MODEL
MSG-278G)
(MODEL
750C)
.
Fig.
8
FM
RECEPTION
FREQUENCY
RANGE
ADJUSTMENT
(See
Figs.
7
and
8).
Connect
the
FM
Signal
Generator
Output
to
the
3002
impedance
FM
Antenna
Terminal
of
Model
AS-8100
through
the
termination
pad.
Introduce
an
882
45W
dummy
load
resistor
to
the
left
channel
speaker
output
and
connect
a
distortion
meter
to
this
output.
At
this
time,
with
speaker
output
at
10
dB,
set
Speaker
Surround
Balance
Shift
to
Front/Left
position.
Set
the
FM
Signal
Generator
to
90
MHz
(400
Hz,
30%
internal
modulation
and
the
output
to
90
dB.
4)
5)
6)
Adjust
the
core
of
Oscillator
Coil
“Lo”
of
FM:
Local
Oscillator
in
front
end
so
that
the
distortion
meter
level
is
maximum
and
the
distortion
factor
is
minimum,
Set
the
tuning
indicator
to
the
right
end
of
the
dial.
Set
the
FM
Signal
Generator
frequency
to
106
MHz.
Adjust
Trimmer
Condenser
**TCO”
in
front
end
so
that
the
distortion
meter
level
is
maximum
and
the
distortion
factor
is
minimum.
Repeat
items
2)
through
5)
two
or.
three
times
until
perfect
reception
is
obtained
in
the
reception
frequency
range
of
87
to
109
MHz.

4.
OUTPUT
TERMINATION
PAD
{MODEL
MR-201I0)
TERMINAL
FM
SIGNAL
GENERATOR
(MODEL
MSG-2786)
DISTORTION
METER
|
OSCILLOSCOPE
-
(MODEL
760C)
Fig.
9
fs
FM
TUNER
TRACKING
ADJUSTMENT
(See
Figs.
7
and
8)
Use
the
same
instruments
as
in
item
3
(Fig.
8)
and
connect
them
in
the
same
way.
1)
2)
4)
5)
Set
the
FM
Signal
Generator
frequency
to
98
MHz
(400
Hz,
75%
internal
modulation)
and
the
output
to
16
dB.
Set
the
Tuning
Dial
to
receive
the
98
MHz
signal.
Adjust
core
“IF’’
of
coil
in
front
end
so
that
the
distortion
meter
level
is
maximum
and
the
dis-
tortion
factor
is
less
than
0.3%.
Set the
FM
Signal
Generator
frequency
to
106
MHz
and
set
the
tuning
dial
to
receive
the
106
MHz
signal.
Adjust
Trimmer
Condensers
“TCA”,
“TCR
1”
and
“TCR
2”
in
the
front
end
so
that
the
distortion
meter
level
is
maximum
and
the
distortion
factor
is
less
than
0.3%.
Set
the
FM
Signal
Generator
frequency
to
90
MHz
and
set
the
tuning
dial
to
receive
the
90
MHz
signal.
Adjust
cores
“LA”,
“LR
1”
and
“LR
2”
in
front
end
so
that
the
distortion
meter
level
is
maximum
and
the
distortion
factor
is
minimum.
Repeat
items
1)
through
4)
two
or
three
times
until
perfect
tracking
and
maximum
reception
sensitivity
is
obtained
at
90
MHz,
98
MHz,
and
106
MHz.
Note:
When
the
distortion
factor
is
0.3%,
the
generator
3.
1)
output
level
is
less
than
16
dB.
MUTING
SENSITIVITY
ADJUSTMENT
(See
Figs.
9
and
10)
Set
the
Signal
Generator
output
level
to
26
dB
(+3
dB)
and
connect
this
output
to
the
FM
Antenna
Terminal
of
Model
AS-8100
through
the
termi-
nation
pad,
and
connect
the
vertical
input
of
the
Oscilloscope
as
well
as
the
distortion
meter
input
-to
Terminal
(8)
(AF
Output)
of
AM
IF
PC.
Board.
3)
4)
2)
4)
Fig.
10
Turn
Muting
Level
Adjustment
Semi-Fixed
Re-
sistor
VR-1
(68
KB)
in
FM
IF
P.C.
Board
fully
clockwise
and
set
FM
Mute
Lever
to
“Off”
position.
Turn
semi-fixed
resistor
VR-1
counter-clockwise
to
position
at
which
Oscilloscope
sine
wave-
form
is
completely
erased
(do
not
turn
beyond
this
point).
If
in
this
waveform
erasing
process,
the
waveform
is
not
erased
and
appears
as
in
Fig.
10,
the
mute
circuit
is
defective.
.
If
perfect
adjustment
cannot
be
made
by
adjusting
muting
sensitivity
volume
VR-1,
because
this
is
due
to
poor
alignment
of
Coil
““L,”
(05M-755),
in
the
mute
circuit,
adjust
the
core
of
“L,”
for
improved
mute
circuit
sensitivity.
TUNING
INDICATOR
CHECK
AND
DISTORTION
ADJUSTMENT
Use
the
same
instruments
as
in
Section
5
(Muting
Sensitivity
Adjustment)
and
connect
them
in
the
same
way.
Set
the
FM
Signal
Generator
Output
to
66
dB,
and
connect
this
output
to
the
FM
Antenna
Terminal
of
Model
AS-8100
through
the
termination
pad.
Connect
the
Oscilloscope
Vertical
Input
as
well
as
the
Distortion
Meter
Input
to
Terminal
(8)
(AF
Output
Terminal)
of
FM
IF
P.C.
Board.
Set
the
FM
Signal
Generator
frequency
to
98
MHz,
and
set
the
tuning
dial
of
Model
AS-8100
to
the
same
98
MHz
frequency.
Adjust
the
upper
core
of
“Ly”
(O05M-775A)
so
that
the
tuning
indicator
needle
is
centered,
and
adjust
the
lower
core
of
“L,”
to
obtain
the
least
distortion.

FM
STEREO
FM
SIGNAL
MODULATOR
GENERATOR
(MSG-
2110)
(MSG
-278G)
OUTPUT
TERMINATION
PAD
AS-8100
SPEAKER
(MODEL
2151B)
7.
SEPARATION
ADJUSTMENT
1)
2)
3)
4)
5)
6)
(See
Fig.
11)
Set the
FM
Stereo
Modulator
Pilot
Signal
19
KHz
to
10%
modulation
and
the
main
signal
(L
+
R)
to
400
Hz,
90%
modulation.
Connect
this
composite
signal
(ratio
9:1)
to
the
EXT
MOD
Terminal
of
the
FM
Signal
Generator.
Set
the
FM
Signal
frequency
to
98
MHz
and
set
this
output
level
to
66
dB,
and
connect
to
the
FM
Antenna
Terminal
of
Model
AS-8100.
Connect
a
high
sensitivity
V.T.V.M.
or
an
8Q
more
than
45W
dummy
load
resistor
to
the
various
speaker
output
terminals.
Set
Tone
Control
to
“Flat”
position
and
then
set
the
tuning
dial
to
98
MHz
and
speaker
output
to
20
dB.
Turn
Separation
Adjustment
Volume
VR-3
(1
KB)
fully
clockwise.
Set
the
FM
Stereo
Modulator
to
right
channel,
and
adjust
the
cores
of
“L,”
and
“L,”
coils
so
that
the
indication
of
V.T.V.M.
(connected
to
left
channel)
is
minimum.
Then
turn
VR-3
counter-clockwise
to
position
at
which
the
V.T.V.M.
indication
is
minimum.
Set
FM
Stereo
Modulator
to
left
channel
and
adjust
the
cores
of
“L,”
and
“L,”
so
that
the
indication
of
V.T.V.M.
(connected
to
right
chan-
nel)
is
minimum.
Then
adjust
VR-3
so
that
the
V.T.V.M.
indication
is
minimum.
If
separation
is
not
better
than
35
dB,
repeat
the
above
adjustments
again.
Avoid
turning
the
coil
cores
too
much
when
making
this
second
adjust-
ment.
If
the
FM
Signal
Generator
output
has
been
decreased
to
26
dB
(+3
dB),
check
to
see
whether
the
stereo
indicator
lamp
has
been
extinquished.
8.
1)
2)
3)
4)
OUTPUT
(MODEL
164)
V.LV.M.
Fig.
11
"AM-FM
RADIO
IF
GENESCOPE
(MODEL
MSW-72IC)
Fig.
12
AM
IF
CIRCUIT
ADJUSTMENT
(See
Figs.
12
and
13)
Adjust
the
V-Gain
Volume
to
obtain
a
2
cm
amplitude
of
0.3V
p-p
AM
FM
Radio
IF
Gene-
scope
calibration
voltage
on
screen,
and
set
the
Genescope
output
to
60
dB.
2cm
pr
een
Fig.
13
Connect
Genescope
output
to
Test
Point
(TP)
and
Genescope
Input
to
Point
(8)
(AF
Output).
Set
Mode
Switch
to
“AM”
and
reception
fre-
quency
to
about
1630
kHz.
Adjust
cores
of
IFT,
T,;,
T,,
and
T,;
of
AM
IF
Amp
P.C.
Board
so
that
the
waveform
(Fig.
13)
level
is
maximum
and
center
frequency
is
455
kHz
(Center
frequency
differs
according
to
country.
Adjust
according
to
country’s
center
frequency).

9.
1)
2)
3)
4)
5)
6)
OUTPUT
TERMINATION
PAD
(MR-2010)
AS-8100
EXT
AM
ANTENNA
INPUT
L-CH
an
45w
SPEAKER
OUTPUT
AM
SIGNAL
GENERATOR
(MSG-230E)
AS-8100
TERMINATION
PAD
(MR-2010)
DISTORTION
METER
(MODEL
760C)
Fig.
14
AM
SIGNAL
GENERATOR
(MSG
-230E)
AM
RECEPTION
FREQUENCY
RANGE
ADJUSTMENT
(See
Fig.
14.)
Connect
the
AM
Signal
Generator
output
to
the
EXT
AM
Antenna
input
terminal
of
Model
AS-
8100
through
the
termination
pad.
Introduce
an
8Q
more
than
45W
dummy
load
resistor
to
the
left
channel
speaker
output
and
connect
a
dis-
tortion
meter
to
this
output.
At
this
time,
set
speaker
output
level
to
10
dB
and
the
Surround
Balance
Shift
to
Front/Left
position.
Set
the
tuning
indicator
to
the
left
end
of
the
dial.
Set
the
AM
Signal
Generator
frequency
to
525
kHz
(+5
kHz),
(400
Hz,
30%
modulation)
and
the
output
to
70
to
80
dB.
Adjust
the
core
of
AM
Local
Oscillator
Coil
“L”
(094-465)
in
the
AM
IF
P.C.
Board
so
that
the
distortion
meter
level
is
maximum
and
the
dis-
tortion
factor
is
minimum.
Set
the
tuning
indicator
to
the
right
end
of
the
dial.
Set
the
AM
Signal
Generator
frequency
to
1530
kHz
(£5
kHz).
Adjust
Trimmer
Condenser
“TC3”
in
front
end
block
so
that
the
distortion
meter
level
is.
maxi-
mum
and
the
distortion
factor
is
minimum.
Repeat
adjustments
outlined
in
items
2)
through
5)
above
two
or
three
times
until
perfect
reception
is
obtained
in
the
reception
frequency
range
of
525
to
1530
kHz.
2)
3)
4)
5)
6)
7)
8)
DISTORTION
METER
(MODEL
760C)
Fig.
15
AM
TUNER
TRACKING
ADJUSTMENT
(See
Fig.
15)
Connect
the
Signal
Generator
output
to
the
AM
input point
of
Mode!
AS-8100
through
the
termi-
nation
pad.
Introduce
an
882
more
than
45W
dummy
load
resistor
to
the
left
channel
speaker
output
and
connect
this
output
to
the
distortion
meter
input.
At
this
time,
with
speaker
output
level
at
10
dB,
set
Speaker
Surround
Balance
Shift
to
Front/Left
and
Tone
Control]
to
“Flat”
position.
Set
the
AM
Signal
Generator
frequency
to
1400
kHz
(400
Hz,
30%
internal
modulation)
and
the
output
to
21
dB.
Set
the
tuning
dial
to
receive
the
1400
kHz
signal.
Adjust
Trimmer
Condensers
“TC
1”
and
“TC
2”
in
the
front
end
so
that
the
distortion
meter
level
is
maximum
and
the
distortion
factor
is
minimum.
Set the
AM
Signal
Generator
frequency
to
600
kHz
and
set
the
tuning
dial
to
receive
the
600
kHz
signal.
Adjust
the
core
of
coil
“L,”
(05M-741
A)
in
AM
IF
P.C.
Board
as
well
as
core
of
the
Bar
Antenna
so
that
the
distortion
meter
level
is
maximum
and
the
distortion
factor
is
less
than
10%.
Set the
AM
Signal
Generator
frequency
to
1,000
kHz
and
set
the
tuning
dial
to
receive
the
1,000
kHz
signal.
Check
to
confirm
that
the
distortion
meter
level
is
maximum
and
the
distortion
factor
is
less
than
10%.
Repeat
items
2)
through
6)
above
two
or
three
times
until
perfect
tracking
is
obtained
at
these
three
frequencies.
Note:
When
the
distortion
factor
is
10%,
the
Generator
output
level
is
less
than
21
dB.

V.
MAIN
AMPLIFIER
ADJUSTMENT
Fig.
16
AUDIO
OSCILLATOR
OUTPUT
O
sae
OSCILLOSCOPE
Fig.
17
1.
IDLING
CURRENT
ADJUSTMENT
(See
Fig.
16)
Set
Mode
Switch
to
“Surround”.
Remove
fuse
from
fuse
holder
and
connect
ammeter
to
both
of
the
fuse
termi-
nals
(match
+
and
—).
Adjust
semi-fixed
resistor
VR-2
(200Q
B)
to
obtain
an
ammeter
indication
of
35
mA.
2.
OUTPUT
WAVEFORM
ADJUSTMENT
(See
Figs.
17
and
18)
1)
Connect
Audio
Oscillator
to
the
“Aux”
input
terminals
of
Model
AS-8100
and
connect
an
82
:
more
than
45W
dummy
load
resistor
to
the
ie
Res
BeOUIIeY
Fig.
18
speaker
output
and
then
connect
this
terminal
to
the
oscilloscope
vertical
input.
2)
Turn
Volume
Control
to
maximum.
Adjust
Audio
Oscillator
Attenuator
to
point
at
which
the
speaker
output
waveform
distortion
is
least
and
supply
this
input
voltage
to
the
“Aux”
terminal.
3)
Adjust
semi-fixed
volume
VR-I
(20
KB)
so
that
the
clipping
position
of
the
upper
and
lower
parts
of
the
waveform
on
the
oscilloscope
are
equal.

AUDIO
SIGNAL
GENERATOR
AS-8100
120W
8
DUMMY
LOAD
RESISTOR
Fig.
20
Supply
output
from
the
Audio
Signal
Generator
to
the
various
“Aux”
output
terminals
of
Model
AS-8100.
Connect
a
dummy
load
resistor
equip-
ped
with
resistor
value
switch
to
the
various
speaker
output
terminals
as
shown
in
Fig.
20
and
connect
this
output
terminal
to
the
Oscilloscope
input
terminal.
Turn
EPC
Operating
Point
Adjustment
Semi-Fixed
Resistor
VR-1
(1
KB)
fully
clockwise.
Set
Mode
Selector
Switch
to
“Stereo”
and
set
dummy
load
resistor
switch
to
8Q
position.
Adjust
volume
control
to
obtain
an
undistorted
oscillo-
scope
waveform
of
maximum
value.
At
this
condition,
set
dummy.
load
resistor
switch
to
“2.7Q”
position
and
turn
operating
point
adjustment
semi-fixed
resistor
VR-1
counter-clock-
wise
to
the
point
at
which
the
output
waveform
is
erased
and
from
this
point,
turn
clockwise
again
about
20°
from
erased
point.
With
a
2.7Q
dummy
ioad
resistor,
the
waveform
will
appear
as
shown
in
Fig.
21.
Set
Mode
Switch
to
“Surround”
and
manipulate
Surround
Balance
Shift
to
check
whether
or
not
EPC
functions.
If
EPC
functioned
during
this
check,
turn
EPC
operating
point
adjustment
semi-
-
fixed
resistor
slightly
further
clockwise.
SPEAKER
OUTPUT
VI.EPC
(ELECTRONIC
PROTECTION
CIRCUIT
)
ADJUSTMENT
DUMMY
LOAD
RESISTOR
OSCILLOSCOPE
Fig.
19
Fig.
21
Waveform
when
the
dummy
load
resistor
is
2.7Q
In
the
check
outlined
in
item
5),
if
EPC
did
not
function,
try
shorting
the
various
speaker
output
terminals.
Check
to
confirm
that
no
matter
which
terminal
is
shorted,
EPC
functions.
When
making
this
check,
even
if
a
single
waveform
is
not
erased,
turn
EPC
operating
point
adjustment
semi-fixed
resistor
slightly
further
clockwise.
When
EPC
functions
regardless
of
which
speaker
output
terminal
is
shorted,
EPC
adjustment
is
perfect.

VIL
DISPOSITION
OF
EACH
ADJUSTMENT
PART
We)
SOE
TR2
L]
O5M-755
L2
ee
ice
OSM
“775A
cr
[oM24
Fig.
23.
81-5050
MPX
AMP
P.C.
BOARD
‘
LO)
1-144
HI-
1345
HI:
1375
Osh
465
OSM
a
Ol
3
[slp
[S]b
@[98
[9]
a
COD
ee
Fig.
24
81-5047
AM
IF
AMP
P.C.
BOARD
©.

.
“Tl
ONT
200¢
oS
O
(
(ie
©
Q
Fig.
26
81-5049
MAIN
AMP.
P.C.
BOARD

VIII.
COMPOSITE
VIEWS
OF
COMPONENTS
FM
IF
AMP.
P.C.
BOARD
(81-5045)
TO
SW7e
FROM
POWER
FROM
SUPPLY
FRONT
END
TO
MPX
PNK/BLK
TO
SW
7d
ORG/BLK
FROM
FRONT
END
FROM
MPX
WHT/BLK
MPX.
AMP.
P.C.
BOARD
(81-5050)
FROM
POWER
FROM
FM
IF
Towwo.g
SUPPLY
Foe
Spy
Rii
62K
RIG
68K
ge
o>
Se
oe
14
:

AM
IF
AMP.
P.C.
BOARD
(81-5047)
BLU
:
La
RED/WHT
FROM
BAR
ANTENNA
ORS
TO
SW7a
and
SWw7b
a
Swi
=
ORC
WT
TO
FRONT
END
TO
FRONT
END
TO
SW74
POWER
SUPPLY
P.C.
BOARD
(81-5044)
4
—
=
3
$5
x
x
0
3e
4
Dw
@ o
z=
SF
g
Pe
=~
DS
FB
ra
Of
Oe
4
x
x
TO
POWER
AMPLIFIER
FROM
POWER
YLW/GRN
TRANSFORMER
TO
PHASE
INVERTER
P.C.BOARD
8
TO
POWER
AMPLIFIER
WHT
TO
IND
7
4-@
WHT/BLU
é
eels
ote
cea
é
FROM
POWER
:
po
. ‘
TRANSFORMER
YLW/RED
A
Wie
€
SN
'
GRN
TO
TONE
CONTROL
2
PC.
BOARD
4
+)
=|
k
O&
Zz
0s
27
a
BO?e
Be
*
Bs
a,
™
Sx
ee.
3
0
fon
a
8
m
=
2
S
15

MAIN
AMP.
P.C.
BOARD
(81-5049)
GRN/BLU
TO
SW
7a
WHT/BLU
I~
FROM
POWER
SUPPLY
PC.
BOARD
FROM
PHONO
INPUT
JACK
RED/8'
TO
SW
7b
YLW/BLU
16

TONE
CONTROL
AMP.
P.C.
BOARD
(81-5048)
FROM
VOLUME
CONTROL
PC.BOARD
BLK/WHT
|
TO
Sw4
=<
TO
SW7a
and
TO
SW7b
GRY/WHT
FROM
VOLUME
CONTROL
PC.BOARD
POWER
SUPPLY
YLW/RED
FROM
yseeaseeneenacnenscr
cag
OES
_|POWER
SUPPLY
RED/BLK
>TO
SWS
VLT/BLK
BLU/BLK
GRN/BLK
17

VOLUME
CONTROL
P.C.
BOARD
(81-5051)
“4
So
w
=
a
y
Q3Y/AN9
ANG
WHS
TO
SW3
Yiw
2”
GRY/GRN
SS
ie
VLT/RED
SS
‘
/
TO
SW2
GA
a
37
TO
Sw2
BRN/RED
GRN/WHT
ee
TO
TONE
CONTROL
w
P.C.
BOARD
TO
TONE
CONTROL
PC.
BOARD
YLW/WHT
GRY/YLW
TO
SW3
GRY/WHT
TO
TONE
CONTROL
PC.
BOARD
Sy
Reo
0Rs
TO
MAIN
DJ
«
Je
FROM
AMPLIFIER
a
VR2C
YLW/BLU
To
SW
9e
-—
YLW/GRN
FROM
POWER
SUPPLY
PCBOARD
WHT/BLU
TO
SW
9d
C=
YLW
df
i
:
o
TO
MAIN
C=
é
NL
VLT/oRG
AMPLIFIER
i
2
SS
From
VR2b
BLK
FROM
POWER
SUPPLY
PC.
BOARD
18

MEMOS:
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