Power Module Circuit (U + Is On, V – Is On) - Hitachi RAS-25CNH1 Service Manual

‡
0
zzz
µ
1000 F
B
R806
‡
0
DC current (Id)
detection resistor
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:
Control P.W.B.
Fig. 3-5
Simplified check of power module (Lighting mode when operated with compressor leads disconnected)
(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 91) for independent checking of power module.
Power module
‡
0 0
0 0
£
£
+
+
U 0
V 0
£ £
- -
U V
‡
0
0
MP6501
Fig. 3-4 Power module circuit (U + is ON, V – is ON)
}
LD301 Red
LD302 Red
Self-diagnosis lamps
LD303 Red
– 69 –
0
0
£
A
+
0
W
U
V
W
£
-
W
0 0 0
Table 3-1
Self-diagnosis
lp (peak current cut)
Abnormal low speed
rotation
Switching incomplete
Switching incomplete
DC compressor
U coil
motor
V coil
W coil
Self-diagnosis lamp
and mode
Blinks 2
LD301
times
Blinks 3
LD301
times
Blinks 4
LD301
times
Blinks 10
LD301
times