Mitsubishi PUMY-P60NKMU Technical & Service Manual page 54

Check code
4220
●Diagnosis of defectives
Make sure to turn the power OFF before connecting/disconnecting
any connectors, or replacing boards.
Continued from the previous page
Is CN5 connected properly
without any contact failure?
Is there any breakage of CT1 on
the noise fi lter board?
Check the bus voltage read by the microprocessor
with an operation of SW1 on the outdoor controller
board.
Is the power supply normal?
Check the bus voltage at the both ends of
R80 on the outdoor power board using a
tester.
Is the bus voltage normal?
The difference on the voltage between
the one read by the microprocessor and
the one at the both ends of R80 is large.
OCH502C
Voltage shortage/Overvoltage/PAM error/T open-phase/
Power synchronization signal error
Diagnosis
Yes
No
Yes
Yes
Yes
No
The black square (■) indicates a switch position.
No
Yes Malfunction of noise fi lter CT1.
Replace the outdoor power board
(Defective outdoor power board).
The bus voltage can be displayed by an
operation of SW1 on the outdoor controller
board.
SW1 Setting
Display on LED1,2
ON
0 999.9
OFF
1 2 3 4 5 6 7 8
Decrease of power supply voltage.
No
T open-phase.
Replace the outdoor power board
No
(Defective outdoor power board).
Replace the outdoor power board
Yes
(A HIC trouble is suspected).
Check the power supply facility
(Check if a receiving electricity is lowered).
54
Chart 2 of 2
Remedy
Correct the CN5 wiring.
Unit
V