Mitsubishi Electric CAHV-R450YA-HPB Service Manual page 165

[ X Troubleshooting ]
Control Circuit
-6- Control Circuit
Troubleshooting transmission power circuit of outdoor unit
HWE22020
Check the voltage at the indoor/outdoor
transmission terminal block (TB3) of outdoor unit.
24 ~ 30 VDC
NO
Check the voltage at TB3 after removing transmission line from TB3.
24 ~ 30 VDC
NO
Check whether the male connector is connected to
the female power supply connector (CN40).
NO
Connected
YES
Check voltage of terminal block for centralized control (TB7).
24 ~ 30 VDC
NO
Check voltage of TB7 by removing transmission line from TB7.
24 ~ 30 VDC
NO
Check the voltage between No.1 and No.2 pins of the
CNS2 on the M-NET board.
24 ~ 30 V DC
NO
Check the voltage between No.1 and No.2 pins of the
CN102 on the M-NET board.
24 ~ 30 V DC
NO
Check the voltage between No.1 and No.3 pins of the
CNDC2 on the REC board .
DC
279 ~ 374 V
NO
Check the voltage between No.1 and No.3 pins of
the CNDC1 on the .
REC board
DC
279 ~ 374 V
NO
Check the noise filter F3 fuse.
F3 blown
NO
Check the voltages among TB23 and TB24 on the
noise filter.
A
YES
Check whether the transmission line is disconnected,
check for contact failure, and repair the problem.
YES
Check if the indoor/outdoor transmission line is not
short-circuited, and repair the problem.
Check the wiring between the control board and M-NET board
YES
for the transmission line (CN62, CNPS, CN102 and CNIT),
and check for proper connection of connectors.
YES
NO
Is there a wiring
Fix the wiring and connector
error or a connector
disconnection.
disconnection?
YES Check for shorted transmission
line or power feed collision for
centralized control.
YES
Replace the M-NET board.
YES
YES
Is there a connector
Fix the connector disconnection.
disconnection?
NO
Check the voltage between No.5 and No.2 pins of
the CNPS on the control board.
YES
Is the voltage
NO
measurement between
Replace the M-NET board
3.2 and 3.4 VDC?
YES
Replace the control board.
YES
Replace the M-NET board
YES
Disconnect the REC board CNDC1, CNDC2 and CNDC3,
and then replace F3, then turn the power on.
YES
F3 blown
Replace the noise filter.
NO
Connect the REC board CNDC2, and then turn the power on.
YES
F3 blown
Replace the control board.
NO
Connect the REC board CNDC3, and then turn the power on.
YES
F3 blown Replace the inverter board.
NO
B
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