SiME332106E
Check
Part 6 Service Diagnosis
275
6.4 Power Transistor Check
CHECK 4
RXYMQ4AVMK
Use a multimeter to measure the resistance to determine if the power transistor is defective or
not.
1. Do not touch live parts (high voltage parts) within 10 minutes after turning off the power
supply.
2. Touch the earth terminal with your hand to release static electricity. (This is to avoid
damaging the PCB.)
3. Use a multimeter to measure the C+ and C- on the PCB to make sure that the residual
voltage of the power transistor is under 50 VDC.
4. After verifying the residual voltage, pull out the outdoor fan motor connector.
If a strong wind causes the outdoor fan to rotate, the capacitor may store electricity.
Therefore, make sure that the fan is still and then pull out the outdoor fan motor connector.
5. Disconnect the connection wire between the power transistor and the compressor.
Remove the connection wire from the compressor.
At this point, make sure that there is no deformation of the Faston terminal at the front end of
the connection wire.
6. Use a multimeter to measure the resistance listed in the table.
Among the three phases listed in the table, if there is one phase with unbalanced resistance
(with a value five times higher than the other values), then the power transistor is defective.
When normal, all phases have the same resistance value.
Multimeter
Resistance
Multimeter
Resistance
Red (+)
Black (–)
Red (+)
Black (–)
C+
U
C–
U
C+
V
C–
V
C+
W
C–
W
U
C+
U
C–
V
C+
V
C–
W
C+
W
C–
Blue
White
Red
Outdoor unit PCB
Compressor
