Mitsubishi Electric MXZ-4C36NAHZ Service Manual page 106

Check method of M-NET power circuit board
M-NET power circuit board check
Check the voltage between M1 and M2 on the
transmission terminal block TB3.
24–30 V DC?
Yes
(24–30 V DC )
Normal
24–30 V DC
Multi controller circuit board
4 3 2 1
2 1
CN102
CNS1
(WHT)
(RED)
24–30 V DC (Non-polar)
TB3 M1 M2
To branch box
OCH573
* To check the voltage of the parts on this board with a tester is difficult due to its location.
Test points are limited.
No
Is the incoming main voltage
208/230 V ±10% AC?
Yes
(208–230 V AC )
Disconnect the branch box - outdoor transmission wiring
from the terminal block TB3 , and check the voltage
between M1 and M2 on TB3 again.
24–30 V DC?
• Check wiring.
• Replace M-NET power circuit board.
M-NET power circuit board
CN2
106
• Check breaker and incoming power supply.
No
• Check power circuit board.
• Check wiring.
Yes
(24–30 V DC )
No
• Correct the short circuit point on
the M-NET transmission line.
CN1
Power circuit board
208/230 V
±10% AC
NI
1 L2
LI
3 L1
CNAC1(WHT)
TB1
208/230 V
±10% AC