Onkyo TX-NR901 Service Manual page 79

IC BLOCK DIAGRAMS AND DESCRIPTIONS
Q7102 TC74HCT7007AF(Hex buffer)
1A 1
1Y 2
3
2A
4
2Y
5
3A
6
3Y
7
GND
(TOP VIEW)
Q190 TC74VHC157FT(Quad 2-channel Multiplexer)
SELECT
S G
A
1A
A
B
1B
B
Y
1Y
Y
A
2A
A
B
2B
2Y Y B
Y
GND
(TOP VIEW)
Q120 TC74VHC4040FT(12-stage ripple-carry binary counter)
Q12
1
Q6
2
Q5
3
Q7
4
Q4
5
Q3
6
Q2
7
GND
8
Vcc
14
6A
13
6Y
12
11 5A
10 5Y
Truth table
4A
9
A Y
4Y L L
8
H H
16 Vcc
15 ST
14 4A
INPUTS
13
4B
ST SELECT A
H X X
12
4Y
L L L
11 3A
L L H
10 3B
L H X
9 3Y
L H X
X:Don't care
16
Vcc
15
Q11
14
Q10
CK CLR
13
Q8
12
Q9
X H
11
CLR
L
10
CK
L
9
Q1
X: Don't care
(15)
ST
SELECT
OUTPUT
B
1A
1B
X L
2A
X
L
2B
X H
3A
L
L
3B
4A
H H
4B
CLR
OUTPUT
(10)
All "L"
CK
No change
Next condition
TX-NR901
(1)
(2)
(4)
MUX
1
1Y
(3)
1
(5)
(7)
2Y
(6)
(11)
(9)
3Y
(10)
(14)
(12)
(13) 4Y
RCTR 12
(9)
Q1
0
(7)
Q2
(6)
Q3
(11)
CT=0
(5)
Q4
(3)
Q5
(2)
Q6
(4)
+CT
Q7
(13)
Q8
(12)
Q9
(14)
Q10
(15)
Q11
(1)
Q12
11