Mitsubishi Electric City Multi CMB-P1016NU-G, Service Handbook

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[
IX
Troubleshooting ]
(2) Troubleshooting transmission power circuit of heat source unit
Check the voltage between 1 and 3 of INV board CNDC2.
Check the voltage at the power supply terminal block (TB1)
of the heat source unit.
Check if the connector on the heat source unit
board is not disconnected.
NV board
: CNDC2 G/A board : CNDC1
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
Check the wiring inside the heat source unit.
G/A board: CNDC1 - INV board: CND2
Check the fuse (F01) on the G/A board.
Check the diode stack.
Check the rush current protection resistor.
YES
DC 250 ~ 310 V
Replace the INV board.
AC 208 / 230 V 10% Check and repair power source wiring and main power source.
Disconnected?
Connect it.
Faulty wiring?
Repair wiring.
Replace the fuse.
Broken?
Broken?
Replace the rush current protection resistor.
Replace the diode stack.
19 ~ 25
Turn on the power again.
Check whether the male connector is connected to
the female power supply connector (CN40).
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
Check if the connector (CNL1 and CNL2) on the
INV board are not disconnected.
Check if the indoor/heat source transmission line is not
short-circuited, and repair the problem.
Check whether the transmission line is disconnected, check
for contact failure, and repair the problem.
Connected
Check the wiring between connectors (CNS1 and TB3).
Check if the connector (CNS1) is not disconnected.
Disconnected? Connect it.
Connect it.
Replace the main board.
DC 24 ~ 30 V
NO
Check the voltage between 1 and 2, and 1 and 3 of main board CNVCC1
DC 24 ~ 30 V
Check the voltage between 1 and 2, and 1 and 3 of main board CNVCC1
DC 24 ~ 30 V
DC 24 ~ 30 V
Check voltage at TB7 by removing transmission line from TB7.
Check voltage at the terminal block for centralized control (TB7).
DC 24 ~ 30 V
Check the voltage at TB3 after removing transmission line from TB3.
YES
NO
DC 24 ~ 30 V
Check the voltage at the indoor/heat source
transmission terminal block (TB3) of heat source unit.
YES
Check and repair wiring between main board connector
(CNVCC1) and INV board connector (CNVCC1).
Check if the transmission line
for centralized control is not short-
circuited, and repair the problem.
YES
Disconnected?
NO
NO