Interface Circuit - Hitachi RAS-50FH5 Service Manual

Fig. 2-1 shows the interface circuit used for the indoor and outdoor microcomputers to communicate with
each other.
5V
R813
L801
R812
Q803
C803
C802
C804
0V
C821 R821
I/F 0V
C822
D101
Terminal board
D C
D C
Terminal board
Interface
relay
0V
C811
C812
L802
5V 5V
R810
Q802
R811
0V
5V 5V
R824
R822
3
2
IC801
0V 0V 0V
Indoor P .W.B.
Outdoor P .W.B.
35V
0V
5V
L801
R801
C801 R802
C809
0V
12V
C807
C802
C806
C810
NF COIL2
C808
I/F 0V
Fig. 2-1 Indoor/outdoor interface Circuit
5V
R805
R803
IC801
5
7
6
R804
R806
C801
0V 0V
5V
5V
R826
R829
D821
R827
1
Q821
C823
0V 0V
5V
0V
Q801
30
0V 0V
5V 5V
29
0V
0V
0V
(Communications from outdoor microcomputer to indoor
microcomputer)
(Communications from indoor microcomputer to outdoor
microcomputer)
– 73 –
IF transmit
50
output (SDO)
0V
MICROCOMPUTER
Q801
IF receive
49
input (SDI)
R830
C824
0V
HIC
5V
5V
0V
0V
0V
0V
IF transmit
11
output (SDO)
MICROCOMPUTER
IF receive
68
input (SDI)