Mitsubishi Electric MXZ-18TV Service Manual page 22

A A Check of power supply
Start
Check the connecting of main circuit parts .
Turn on power supply
Is there voltage of 230V AC in the
power supply terminal block?
Yes
Is there voltage of 325V DC across the
smoothing capacity?
Yes
Replace the outdoor electronic control
P. C. board.
B B Check of outdoor unit serial signal
Start
1. Check the indoor unit with referring to the indoor unit service manual.
2. Turn off the power supply of the indoor and outdoor unit and return the indoor/ outdoor unit connecting wire to former
original.
3. Check the connection of indoor/ outdoor unit connecting wire in the outdoor unit terminal block, and check the connection
of the connector (CN601: unit A, CN602: unit B) in the control P. C. board
4. Disconnect the lead wire to the compressor. Turn on the power supply (indoor/ outdoor unit) 3 minutes later,
EMERGENCY OPERATION starts.
Is there voltage from 5V DC - 10V DC between
No. 3 (+) and N (-) in the outdoor terminal block.
Yes
Recheck a connected circumstance of the indoor/ outdoor unit connecting wire.
No
Check the power supply cable.
Is there voltage of 230V AC across the
No
input terminal part in the diode module
(DS61)?
Yes
Check the main circuit parts
and replace it.
No
Replace the outdoor electronic control P. C. board.
22
Replace the noise
No
filter P. C. board