Hitachi RAM-50CNHZ2, Service Manual, Page: 70 / 107

– 78 –
+
U
U
V
W
–
U
+
V
–
V
+
W
–
W
System power module
260V-360V
DC current (Id)
detection resistor
A
U coil
DC compressor
motor
V coil
W coil
B
●
Since current flows at point B only when U+ transistor is 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 detective, self diagnosis lamps on the control P.W.B. may indicate as shown below:
❈
From results of power module simple inspection (inspection mode when operated with compressor lead
disconnected), LD310 blinks four times about 2 seconds later: Unit has not entered the normal operation.
Fig. 3-4 System power module circuit (U+ is ON, V– is ON)
Self-diagnosis
Self-diagnosis lamp
and mode
lp (peak current cut)
LD301
Abnormal low speed
rotation
LD301
Switching incomplete
LD301
Blinks 2
times
Blinks 3
times
Blinks 4
times
Table 3-1
GRN3
GRN1
Reactor
SPM2
Smoothing capacitor
(C501, C502, C503)
Power P.W.B
Terminal
Board (2p)
Diode Stack
(D25 VB60) Switching Power P.W.B
(For Indoor P.W.B.)
Self-disgnosis lamps
(From left: LD301, LD302, LD303, LD304)
Service-switch
Control P.W.B