Hitachi RAC-18SX8 Service Manual page 147

MODEL RAC-18SX8
1. Power Circuit
CONTROL P.W.B.
F1
A
B
C
TERMINAL
BOARD
GN1
SURGE ABSORBER
SA (103)
GN2
REVERSING VALVE
4
3
2
1
CN2
VH-4P-Top
This circuit produces a DC voltage by changing the AC current of 220 V to 230 V between terminal boards A and
○
B to full-wave rectification and double-voltage rectification by using a diode stack (DB601) and full-wave/double-
voltage relay.
Provided that it enters the range of between about 320 V and 360 V while the compressor is running.
Main components
○
(1) Intelligent power module (IPM)
The module constitutes the inverter.
(2) Diode stack (DB1, DB601, DB602)
This rectifies the current 220 to 230 V AC applied
between terminal boards A and B to a DC current.
NF1
VARISTOR
VS1
L001
C012
CT
0V
12V
C803
0V
R804 C804 L801
L002
DB1
R441
RL1
COOL/HEAT
CHANGING RELAY
TAB2
WJ1
WJ2
RL2
REVERSING
VALVE RELAY
Fig. 1-1
<Reference>
When the intelligent power module fails or becomes
○
poorly connected
It may stop immediately after compressor startup, due
to "abnormally low speed," "unsuccessful failure," "Ip
stoppage," or something similar.
<Reference>
When the diode stack (DB602) fails, it may be because
○
there is no DC voltage, resulting in its total operation
stoppage. Note also another possibility where the 25
A fuse (F1) may have melted down.
○ If the diode stack (DB601) is in a failure, an "abnormal
power supply voltage" may occur.
– 180 –
Cr
L2
TAB3-4
L1
+ +
J9
R08
R02
R01
IPM1
P
U
V
W
N