Hitachi RAS-25CNH2 Service Manual page 48

260V-380V
B
R24
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:
Fig. 3-5
Simplified check of power module (Lighting mode when operated with compressor leads disconnected)
G
(1) Disconnect connector of 3-pole (WHT, YEL, RED) lead wire connecting to compressor located at the
lower part of electric parts box.
(2) Set to compressor operation state (other than FAN mode) and press Start/stop switch of remote
control.
(3) If normal operation continues for more than 1 minute (LD303 lights), power module is considered
normal.
❈ Refer to other item (troubleshooting on page 109) for independent checking of power module.
Power module
+
+ +
U V
– –
U V
_
6DI15S
Fig. 3-4 Power module circuit (U + is ON, V – is ON)
(LD301)
}
(LD302) Self-diagnosis lamps
(LD303)
– 51 –
A
+
W
U
V
W
V coil
–
W
Table 3-1
Self-diagnosis
lp (peak current cut)
Abnormal low speed
rotation
Switching incomplete
DC compressor
U coil
motor
W coil
Self-diagnosis lamp
and mode
Blinks 2
LD301
times
Blinks 3
LD301
times
Blinks 4
LD301
times