Hitachi RAM-60QH4 Manuel De Service page 74

Fig. 2-1 shows the interface circuit used for the indoor and outdoor micro computers to communicate with
each other.
5V
R813
C802 R812
C804
0V
C821 R821
I/F 0V
C822
D101
C Terminal board
D
D C
Terminal board
Interface
relay
12V
0V
C804
C805
L803
HIC
5V 5V
Q803
R810
10
R811
0V
5V 5V
11 11
0V 0V
0V
Indoor P.W.B.
Outdoor P.W.B.
35V
0V
5V
L801
R801
C801 R802
C802
C803
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
5V
0V 0V
5V
5V
0V 0V
5V
Q201
R283
Q802
D801
R803
0V 0V
5V 5V 5V
R262 R259
R263
R261
D206
C216
R260
0V
0V 0V
– 86 –
IF transmit
50
output (SDO)
Micro
0V
computer
IF receive
49
input (SDI)
0V
IC8
2
15
5V
R255
R254
R258
R257
Q206
R256
0V
0V
C214
0V
11 IF-CLOCK
SD01
70
SDI1
69