Service manual

IC BLOCK DIAGRAM
SREV1
24
1
2
3
4
5
6
7
1A
1Y
2A
2Y
3A
3Y
Vss
14
13
12
11
10
9
8
VDD
6A
6Y
5A
5Y
4A
4Y
TC74VHC04F EL (XM332A00)
TC74VHCT04AF (XT777A00)
Hex Inverter
CPU: IC117, 133
TC74VHC08FT (XV891A00)
Quad 2 Input AND
CPU: IC301
TC74VHC32FT (XY945A00)
Quad 2 Input OR
CPU: IC121, 158
TC74VHC74FT (XV892A00)
Dual D-Type Flip-Flop
CPU: IC139
TC74VHC125FT (XY074A00)
Quad 3-State Bus Buffer
CPU: IC146
TC74VHCT126AFT (XY057A00)
Bus Buffer
CPU: IC145
TC74VHC138FT (XZ495A00)
3 to 8 Demultiplexer
CNV: IC19–22
TC74VHC139FT (XV893A00)
Dual 2 to 4 Demultiplexer
CPU:
CNV:
TC74ACT174F (XY938A00)
Hex D-Type Flip-Flop
CPU: IC163, 164
1
2
3
1A
1Y
42A
52B
62Y
7
VSS
1B
14
13
12
VDD
4A
11 4Y
10 3B
93A
83Y
4B
1
2
3
1A
1Y
42A
52B
62Y
7GND
1B
14
13
12
Vcc
4A
11 4Y
10 3B
93A
83Y
4B
INPUTS OUTPUTS
PR CLR CLK D Q Q
L
H
H
L
H
Q
O
H
L
H
H
L
Q O
X
X
X
H
L
X
X
X
X
f
f
L
H
L
L
H
H
H
L
H
L
H
H
H
1
2
3
4
5
6
7
1CLR
1D
1CK
1PR
1Q
1Q
GND
14
13
12
11
10
9
8
VCC
2CLR
CLR
2D
D
2CK
CK
2PRPR
2Q
2QQ
Q
CLR
D
CK
PR
Q
Q
1
2
3
4
5
6
7
1G
1A
2Y
2G
2A
2Y
GND
14
13
12
11
10
9
8
Vcc
4G
4A
4Y
3G
3A
3Y
1
2
3
4
5
6
7
1G
1A
1B
1Y0
1Y1
1Y2
1Y3
A
G
B
Y0
Y1
Y2
Y3
16
15
14
13
12
11
10
Vcc
2G
2A
2B
2Y0
2Y1
2Y2
8
GND
9
2Y3
Y2
Y3
Y1
Y0
B
A
G
1
2
3
4
5
6
7
A
A
Select
Enable
Output
Output
B
B
C
C
G2A
G2A
G2B
G2B
G1
G1
Y7
Y7 Y5
Y4
Y3
Y2
Y1
Y0
Y6
16
15
14
13
12
11
10
Vcc
YO
Y1
Y2
Y3
Y4
Y5
8
GND
9
Y6
Q
Q
DC K C K
C K
DC K
GG
CLEAR
1Q
1D
2D
2Q
3D
3Q
GND
1 16
2 15
3 14
4 13
5 12
6 11
7 10
8 9
Vcc
6Q
6D
5D
5Q
4D
4Q
CK
Q
D
GG
Q
DC K
G
C K
Q
D
G
Q
D
IC157, 169, 171
IC18
1
2
3
4
5
6
7
C1
A1
Y1
C2
A2
Y2
GND
14
13
12
11
10
9
8
Vcc
C4
A4
Y4
C3
A3
Y3