Circuit Description - JVC JX-S555 Service Manual

Circuit Description

1. IC2 (µPD780021ACWW01)
The µPD780021ACWW01 is a 64-pin, 8-bit single-chip microcomputer with an 8K-byte ROM and 512-byte RAM.
Pin Name Pin No.
P40/AD0
P41/AD1
P42/AD2
P43/AD3
P44/AD4
P45/AD5
P46/AD6
P47/AD7
P50/A8
P51/A9
P52/A10
P53/A11
P54/A12
P55/A13
P56/A14
P57/A15
Vss
0
V
DD0
P30
P31
I/O
I/O
1
I/O
2 Key scan inputs.
I/O
3
I/O
4
I/O
5 Key scan outputs.
I/O
6
I/O
7 Scan signal outputs for LED lighting.
I/O
8
I/O
9 Dubbing lock ON/OFF. H = ON. L = OFF.
I/O
10
I/O
11 Scan signal outputs for LED lighting.
I/O
12
I/O
13 CH1 INHIBIT ON/OFF. H = ON. L = OFF.
I/O
14 Not used.
I/O
15 Not used.
I/O
16 Not used.
—
17 Port grounding potential.
I
18 Port positive potential.
I/O
19 CH2 INHIBIT ON/OFF. H = ON. L = OFF.
I/O
20 CH3 INHIBIT ON/OFF. H = ON. L = OFF.
Function
JX-S555(J)
(No. 70251) 7