Hitachi RAS-50WX8 Service Manual page 92

In low speed rotation mode (PWM range), as shown in Fig. 6-2, 0-5V chopper signal is output from microcomputer for each phase. Signal output
from microcomputer is output to IC1 and is inverted by active Lo to become 0-17V chopper signal; it is then applied to each phase transistor gate
to drive.
In high speed rotation mode (PWM range), as shown in Fig. 6-3, 0-5V drive signal is output from microcomputer for each phase (with no chopper
because of full duty). Signal output from microcomputer is input to IC1 and is inverted by active Lo to become 0-17V drive signal; it is then applied
to each phase transistor gate to drive.
P2
HIC
Q501
R521
2
Q502
R531
R522
5
R532
R523
6
V
d
R533
1
3
4
N1
< In Low speed >
17V
0V
17V
0V
Fig. 6-2
MAIN P.W.B.
17V
R411
A
R501
45
R502
44
Q503 R503
43
Q504 R504
R524
42
Q505 R505
R534
R525 41
Q506 R506
R535
R526 40
R536
0V
Fig. 6-1
SPM2
B B B
HIC
12
8 3 14
8
7 4 15
5
16
6 5
IC1
5 6 17
3
4 7 18
6
8
3 19
10
B B B
R24
< In high speed >
17V
0V
17V
0V
Fig. 6-3
COMPRESSOR MOTOR