Mitsubishi Electric MXZ-4C36NAHZ Technical & Service Manual page 111

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 (F500) blow?
No
Did the fuse (F1 and F2) blow?
No
7seg LED is lit?
(SW1: all off)
Yes
(lit)
LED1
Normal
Power
circuit
CN52C
board
(RED)
1 3
13 V DC
Conv.
Circuit
Noise
Filter
Circuit
LI NI
TB1
L1 L2
OCH573E
Disconnect the FAN motor connector and
measure the resistance of connector pins.
Yes
Refer to "8-6. HOW TO CHECK THE PARTS".
(blow)
Yes (blow)
No (No lit)
Check the voltage from the power circuit
board to CNDC (PNK) connector.
LED2
290 to 350 V DC?
Check wiring.
Replace multi controller circuit board.
CNDC (PNK) F500
290–350 V DC
3
1
CNDC
(PNK)
208/230 V AC
±10%
1
3
CNAC2
(RED)
208/230 VAC
±10%
Check the SV1, SV2, SS and 21S4 and wiring.
No
Yes
Check the breaker and main incoming power.
Check power board.
Check wiring.
CN52
F1
F2
CNAC (RED)
Replace multi controller circuit board (MULTI. B.)
and the defective fan motor. See DC fan check.
Multi controller
circuit board