Hitachi RAF-25RPA Service Manual page 64

Fig. 3-1 shows the interface circuit used for the indoor and outdoor microcomputers to communicate with each other.
Control P.W.B.
35V
L101
Terminal board
0V
Terminal board
D C
C
D
Terminal board
Ｍ Ａ Ｉ Ｎ Ｐ． Ｗ． Ｂ.
１ ２ Ｖ
＋
Ｒ Ｌ ３
０ Ｖ
Ｃ ８ ０ ４
Ｌ ８ ０ ２
Ｃ ８ ０ ５
5V
C332 L301
CJ301
0V
C321
R321
0V
Indoor P.W.B.
Outdoor P.W.B.
Ｌ ８ ０ １
Ｃ ８ ０ ２
３ ５ Ｖ
＋
Ｒ ８ ０ ２ Ｑ ８ ０ １
Ｃ ８ ０ １
Ｌ ８ ０ ３
Ｌ ８ ０ ４
０ Ｖ ０ Ｖ
(Communications from outdoor microcomputer to indoor microcomputer)
(Communications from indoor microcomputer to outdoor microcomputer)
Fig. 3-1 Indoor/outdoor interface Circuit
5V
R335
Q334
R333
Q333
0V
R326 R330
3 8
R327
1
2
4
D321
C323
IC301
(1/2)
HYBRID IC BOARD
３ ８
５ Ｖ
５ Ｖ
５ ２
３ ７
Ｑ ２ ０ ３
０ Ｖ
64
R332
Q332
Q331
5V
IC301
(2/2)
6
R650
7
5
R320
0V
Ｒ ２ ５ ８
Ｒ ２ ０ ６
Ｒ ２ ５ ７
３
＋
１
− Ｑ ２ ５ １
２
Ｄ ２ ５ １
４
Ｉ Ｃ ５ （１／２）
０ Ｖ
０ Ｖ
88
52
IF Transmission
Microcomputer
51 IF Reception
Ｍ Ｉ Ｃ Ｒ Ｏ Ｃ ＯＭＰ Ｕ Ｔ Ｅ Ｒ
６ ２
Ｃ ＯＭＭＵ Ｎ Ｉ Ｃ Ａ Ｔ Ｉ Ｏ Ｎ Ｓ Ｓ Ｄ Ｉ
０ Ｖ
４ ４
Ｃ ＯＭＭＵ Ｎ Ｉ Ｃ Ａ Ｔ Ｉ Ｏ Ｎ Ｓ Ｓ Ｄ Ｏ