Mitsubishi Heavy Industries SRRM40HENG-L, Handbook, Page: 176 / 1106

174
SCM-HG (4 room)
(7) Inverter failure diagnosis
If the results of the diagnosis in Item (3) indicate that the inverter is defective, perform the following inspection on the inverter.
Is LED 1 (green) on the printed
circuit board on?
Is there approximately DC 280V
between
P and
N
on the power
transistor?
Is there voltage at U, V and W of the
power transistor?
Is there output at CNJ on the printed
circuit board?
[Electrical abnormalities in outdoor unit]
Is the fuse good?
Is the varistor good?
Is the noise filter good?
Fuse is defective
e
Replace
The varistor is defective
e
Replace
The noise filter is defective
e
Replace
The printed circuit board is
defective
e
Replace
The printed circuit board is
defective
e
Replace
The power transistor is
defective
e
Replace
Inspect compressor.
Condenser is defective
e
Replace
The reactor is defective
e
Replace
The diode stack is defective
e
Replace
The printed circuit board is
defective
e
Replace
Is the diode stack good?
Is there conductivity in the reactor?
Is condenser good?
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
NO
NO NO
NO
NO
NO
NO
NO
NO
NO
(a) Diagnosis procedure
High voltage is created inside the controller box. When performing operations other than inspecting the
voltage system, stop operation and wait until LED7 on the printed circuit board of the outdoor unit has
gone out (approx. 20 minutes) before coming in contact with the components inside the controller box.