Hitachi RAS-25CNH2 Service Manual page 42

Fig. 2-1 shows the interface circuit used for the indoor and outdoor micro computers to communicate with
G
each other.
5V
R812
C805 R813
C808
0V
0V
C801 R802
I/F 0V
C802
D101
0V
Terminal board
D C
D C
Terminal board
Interface
relay
12V
0V
C709
C710
5V 5V
5V 5V
+
–
0V 0V
Indoor P.W.B.
Outdoor P.W.B.
36V
0V
5V
L701
R801
C801 R802 Q802
33
C708
NF COIL3
I/F 0V
Fig. 2-1 Indoor/outdoor interface Circuit
5V
+
–
C806
0V
0V 0V
5V
5V
R810
R811
C803
IC801
0V 0V
5V
32
0V 0V
5V 5V 5V
+
–
0V
0V
0V
(Communications from indoor micro computer to outdoor micro
computer)
(Communications from outdoor micro computer to indoor micro
computer)
– 45 –
IF transmit
64
output (SDO)
MICRO
COMPUTER
IF receive
19
input (SDI)
C804
0V
70
11
5V
69
0V
0V
0V
IF transmit
output (SDO)
MICRO
COMPUTER
AX-8J00
IF receive
input (SDI)