Hitachi RAS-E08H2A - Page 46

– 44 –
Fig. 3-4 Power module circuit (U
+
is OFF, V
–
is ON)
Since current flows at point B only when U
+
transistor and V
–
transistor are ON, the current waveform
at point B becomes intermittent waveform as shown in Fig. 3-3. Since current at point B is approximately
proportional to the input current of the air conditioner, input current is controlled by using DC current
(Id) detection resistor.
<Reference>
If power module is defected, self diagnosis lamps on the MAIN P.W.B. may indicate as shown below:
L
D
303
L
D
302
L
D
301
MAIN
P
.
W
.B
.
SE
R
V
ICE SWIT
C
H
HI
C
I
PM
Fig. 3-5
Table 3-1