4
F-20B
CIRCUIT BOARD LAYOUT
MAIN
1/2
MAIN
1/2
MAIN
1/2
MAIN
2/2
MAIN
2/2
AC Cord
Power Transformer
BLOCK DIAGRAM
+B
+12V
-12V
-B
GND
POWER
AMP
IC4
IC1
IC3
1
2
3
1
1
4
INPUT
FUSE
FZ1
ACTIVE TYPE
TONE CONTROL
POWER SUPPLY CIRCUIT
POWER TRANSFORMER
4
Ω
Speaker
PHONE
AUX IN
CN2 4P
CN1 2P
CN3 3P
CN4 5P
CN5 5P
POWER SWITCH
SW1
T2
T1
T4
T1
T2
G
U, C, S, BS
MAIN
1/2
MAIN
2/2
T3
GAIN SELECT
ACTIVE CH.
PASSIVE CH.
BASS
VR5
LOW MID
VR4
HIGH MID
VR3
TREBLE
VR2
VR1
IC3
5
7
VOLUME
JK3
JK2
JK1
SW2
IC1,IC2
OP AMP
OP AMP
8
4
+12V
-12V
-B
+B
5
3
+12V
-12V
8
4
Top View
Side View
Front View
