Mitsubishi Heavy Industries FDT90VNPWVH Service Manual page 63

(6) Power transistor module (Including the driver PCB) inspection procedure
short circuit between the
power transistor module
Compressor operation
Is there any difference in
the compressor current
* (1) Power transistor module terminal short circuit check procedure
Disconnect the compressor wiring, then conduct a short circuit check.
P-U, P-V, P-W
N-U, N-V, N-W
Check between the P-N terminals.
Bring the tester probes in contact with the following
places on each te rminal.
P: Power transistor P terminal,
N: Power transistor N terminal,
U: End of red harness to compressor
V: End of white harness to compressor
W: End of black or blue harness to compressor
Is the power
YES
transistor module
cracked or burnt?
NO
Is there a
YES
∗
terminals? (1)
NO
YES
between phases?
NO
Normal
-
If there is a 10% or greater difference
in the current in different phases.
(except during acceleration or deceleration)
Check for a power transistor short-circuit.
• When you do not have a diagnostic checker for judging if the inverter
is defective, measure between the terminals of the power transistor
parts, judge whether the power transistor is defective or not.
• Disconnect the compressor, then measure with the control
incorporated.
Model FDC90, 100VNP-W
Tester
Normal values (W)
Terminal Terminal
(+) (-)
P N
N P
P U
P V
P W
N U
A few of MW
N V
N W
U P
V P
W P
U N
V N
W N
If the measured values range from 0 - several k W , there is a possibility that the
elements are damaged, so replace the power transistor parts.
62
-
'19 • PAC-SM-334
Replace the outdoor
unit inverter PCB
Diode mode ( V )
—
(Not short)
Approx. 0.4 V
—