Mitsubishi City Multi PURY-P400 Service Handbook page 88

(7) Transmission Power Circuit (30 V) Check Procedure
If " " is not displayed on the remote control, investigate the cause of the problem by following the procedures listed below
and correct the problem.
No. Check Item
1 Disconnect the transmission line from TB3
and check the TB3 voltage.
2 Check if the following connectors are
disconnected in the outdoor unit's control
box.
MAIN Board: CNS1, CNVCC3, CNVCC4
INV Board: CNVCC2, CNVCC4, CNL2,
CNR, CNAC2
3 Disconnect the wires from CNVCC3 on the
Main board, and check the voltage
between pins 1 and 3 on the wire side of
the CNVCC3.
Tester + ..... 1 pin
Tester - ..... 3 pin
4 Disconnect the wiring from CNVCC2 on the
INV board, and check the voltage between
pins 1 and 3 of CNVCC2.
Tester + ..... 1 pin
Tester - ..... 3 pin
5 Disconnect the wiring from CNL2 on the
INV board, and check the resistance at
both ends of choke coil L2.
6 Disconnect the wiring from CNR on the INV
board, and check the resistance at both
ends of R7.
7 Check the resistance at both ends of F01
on the INV board.
8 Check the voltage between pins 1 and 3 of
CNAC2 on the INV board.
9 Check the voltage between L2 and N on
power supply terminal block TB1.
Judgment
DC24~30 V
Except the above-mentioned
Connector disconnected
Except the above-mentioned
DC24~30 V
Except the above-mentioned
DC24~30 V
Except the above-mentioned
0.5~2.5Ω
Except the above-mentioned
19~25Ω
Except the above-mentioned
0Ω
Except the above-mentioned
AC198~264 V
Except the above-mentioned
AC198~264 V
Except the above-mentioned
–87–
Response
Check the transmission line for the following, and
correct any defects:
Broken wire, short circuit, grounding, faulty
contact.
Go to No. 2
Connect the connectors as shown on the electric
wiring diagram.
Go to No. 3
Check the wiring between CNS1 and TB3 for the
following, and correct any defects:
broken wire, short circuit, grounding, faulty
contact.
If there is no trouble, replace the Main board.
Go to No. 4
Check the wiring between CNVCC2 and
CNVCC3 for the following, and correct any
defects:
broken wire, short circuit, grounding, faulty
contact.
Go to No. 5
Go to No. 6
Replace choke coil L2.
Go to No. 7
Replace R7.
Go to No. 8
Replace F01
Replace the INV board.
Go to No. 9
Check the wiring to CNAC2 for the following and
correct any defects:
broken wire, faulty contact.
Check the power supply wiring and base power
supply, and correct any defects.