Mitsubishi Electric MXZ-SM72TAM-U1 Service Manual page 96

8-7-3. Check method of multi controller circuit board
Multi controller circuit board check
Fuse check
Check the fuse on multi controller circuit board
Did the fuse blow?
No
Did the fuse (F1 and F2) blow?
No
Is 7seg LED lit? (SW1: all off)
Yes
Normal
Power circuit board
Conv.
circuit
Noise
LO1 LO2 LO3
filter
circuit
board
LI1 LI2 LI3
TB1 L1 L2 L3
208/230 V AC ± 10%
OCH800A_96
Disconnect the FAN motor
Yes
connector and measure the
resistance of connector pins.
Refer to "How to check the parts".
Yes
No
Check the voltage from the power circuit
board to CNDC (PK) connector.
LED1 LED2
290 to 380V DC? (1-phase)
290 to 330V DC? (3-phase)
• Check wiring.
• Replace multi controller circuit board.
CNDC (PK)
CNDC
(PK)
1
3
290-330 V DC
CNAC2
(RD)
1
3
208/230 V AC ± 10%
Is the fan motor normal?
No
Replace the outdoor multi controller circuit
board (MULTI.B.) and the faulty fan motor.
Check the SV1, SV2, SS and 21S4 and
wiring.
No
Yes
• Check the breaker and main incoming power.
• Check power board.
• Check wiring.
JP50
F1
F2
Yes
Replace the outdoor multi
controller circuit board (MULTI.B.).
Multi controller circuit board
CNAC (RD)