Hitachi RAM-71QH5 Service Manual page 44

Fig. 2-1 shows the interface circuit used for the indoor and outdoor microcomputers to communicate with
G
each other.
5V
R813
R812
C802
Q803
C804
0V
0V
C821 R821
11
I/F 0V
C822
D101
0V
Terminal board
C
D
D C
Terminal board
35V
Interface
relay
12V
0V
C804
C805
L811
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HIC
5V 5V
R810
10
R811
5V 5V 5V
0V
0V
0V
Indoor P.W.B.
Outdoor P.W.B.
0V
5V
L801
R801
R802 Q801
C801
D210A
R803
0V 0V
R263
C802
R261
C216
C803
0V
NF COIL
I/F 0V
(Communications from indoor micro computer to outdoor micro computer)
(Communications from outdoor micro computer to indoor micro computer)
Fig. 2-1 Indoor / Outdoor interface Circuit 1
– 53 –
5V
0V
0V
0V
5V
0V
0V
5V
Q201
5V 5V 5V
R262 R259
R258
R257
R256
D206
R260
0V
0V
0V
C214
0V
IF transmit
output (SDO)
Micro
computer
IF receive
input (SDI)
73
SDO1
5V
R255
SDI1
68
R254
Q206
0V