Hitachi RAM-40QH5 Service Manual page 43

260V-360V
B
DC current (Id)
detection resistor
Since current flows at point B only when U+ transistor is ON, the current waveform at point B becomes
G
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:
Smoothing Capacitors
(C501, C502, C503)
SPM2
Reactor
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.
System power module
+
+ +
U V
— —
U V
_
Fig. 3-4 Power module circuit (U + is ON, V – is ON)
Diode stack
Switching Power P.W.B.
(D25 VB60) (For Indoor P.W.B)
Table 3-1
Abnormal low speed rotation
– 49 –
+
W
U
V
W
—
W
Service switch
Control P.W.B.
Self-diagnosis lamps
(From left: LD301, LD302, LD303, LD304)
Self-diagnosis
lp (peak current cut)
Switching incomplete
DC compressor
U coil
A
motor
V coil
W coil
Terminal
Power P.W.B.
Board (2p)
Self-diagnosis lamp and mode
LD301 Blinks 2 times
LD301 Blinks 3 times
LD301 Blinks 4 times
Terminal
Board (4p)