Mitsubishi Electric PUMY-P36NKMU2-BS Technical & Service Manual page 109

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
(WH)
(RD)
24–30 V DC (Non-polar)
TB3 M1 M2
To indoor unit
OCH695B
* 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 AC ±10%?
Yes
(208–230 V AC )
Disconnect the indoor unit - outdoor transmission wiring
from the terminal block TB3 , and check the voltage
between M1 and M2 on TB3 again.
24–30 V DC?
No
• Check the wiring.
• Replace the M-NET power circuit board.
M-NET power circuit board
CN2
109
• Check the breaker and incoming power supply.
No
• Check the power circuit board.
• Check the wiring.
Yes
(24–30 V DC )
• Correct the short circuit point on
the M-NET transmission line.
Power circuit board
1
3
CNAC1(WH)
CN1
208/230 V AC
±10%
208/230 V AC
±10%
NI
L2
LI
L1
TB1