Hitachi RAD-25NH7 Service Manual page 60

260V-360V
B
R24
DC current (Id)
detection resistor
Since current flows at point
G
intermittent waveform as shown in Fig. 3-3. Since current at point
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:
P.W.B (Main)
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 94) for independent checking of power module.
System Power Module 2
+
+ +
U V
— —
U V
_
Fig. 3-4 Power module circuit (U + is ON, V – is ON)
only when U+ transistor is ON, the current waveform at point
B
Self diagnosis lamps
(LD303, 302, 301)
A
+
W
U
V
W
—
W
is approximately proportional to the
B
Table 3-1
Self-diagnosis
lp (peak current cut)
Abnormal low speed
rotation
Switching incomplete
– 70 –
DC compressor
U coil
motor
V coil
W coil
B
Self-diagnosis lamp
and mode
Blinks 2
LD301
times
Blinks 3
LD301
times
Blinks 4
LD301
times
becomes