Mitsubishi Electric PURY-HP144, Service Handbook

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[8-11 Control Circuit ]
HWE18220_GB chapter 8 -
59
8 Troubleshooting Based on Observed Symptoms
8-11-2 Troubleshooting Problems with Outdoor Unit Transmission Power Supply
Circuit
1) YNU
YES
YES
NO
NO
A B
NO
8-12 VDC
Fuse F4 is blown.
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
24-30 VDC
24-30 VDC
24-30 VDC
24-30 VDC
24-30 VDC
YES
NO
24-30 VDC
YES
YES
NO
NO
NO
YES
YES
Fuse F4 is
blown.
Check the voltage at the indoor/outdoor
transmission terminal block (TB3) of outdoor unit.
Check whether the transmission line is disconnected,
check for contact failure, and repair the problem.
Check if the indoor/outdoor transmission line is
not short-circuited, and repair the problem.
Check the wiring between the control board and
power-supply board, and also check connectors CNPW,
CNPS, CN202, and CNINT for proper connections.
Check the wiring between the control board and
power-supply board, and also check connectors CNPW,
CNPS, CN202, and CNINT for proper connections.
Correct wiring problems, and tighten loose connectors.
Correct wiring problems, and tighten loose connectors.
Disconnect CN100 on the power-supply board,
replace F4, and turn on the power supply.
Check the voltage at TB3 after removing
transmission line from TB3.
Check whether the male connector is connected to the
female power supply connector (CN40).
Connected
Check voltage of terminal block for centralized control (TB7).
Check voltage of TB7 by removing transmission line from TB7.
Check the voltage across pins 3 and 4 of CNPW on the control board.
Check the voltage across pins 1 and 2 of CNPW on the control board.
Check the voltage across pins 1 and 2 of CN600 on the control board.
Check the wiring between the control board and
power-supply board, and also check connectors
CN600 and CNDC for proper connections.
Check the wiring between the noise filter board and
power-supply board, and also check connectors
CN2, CNTR1, CNTR4, RYNF and CN100 for proper
connections.
Fix the wiring and connector
disconnection.
Correct wiring problems, and
tighten loose connectors.
Check for shorted transmission
line or power feed collision for
centralized control.
Replace the control board.
YES
NO
Any problems with wiring or
loose connectors?
Is there a wiring
error or a connector
disconnection?
Check the voltage across pins 4-1 of CNPS on the control board.
YES
Replace the
Transformer in the
Transformer Box.
Replace the control board.
Replace the power-supply board.
3.25-3.35 VDC
YES
NO
Replace the power-supply board.
Any problems with wiring or
loose connectors?
Any problems
with wiring or loose
connectors?
Check fuse F4 to the left of power supply terminal
block TB1.