The Lcd Momentarily Lights Up And Then Goes Off - Mitsubishi Electric PURY-HP72 Service Handbook

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[8-1 MA Remote Controller Problems ]

The LCD Momentarily Lights Up and Then Goes Off.

1. Phenomena
When the remote controller operation SW is turned on, the operation status briefly appears on the display, then it goes off,
and the display lights out immediately, and the unit stops.
2. Cause
1) The power for the M-NET transmission line is not supplied from the outdoor unit. For details, refer to the following page(s).
[8-12-2 Troubleshooting Problems with Outdoor Unit Transmission Power Supply Circuit](page 308)
[8-13-2 Troubleshooting Problems with Outdoor Unit Transmission Power Supply Circuit](page 310)
2) Short circuit of the transmission line.
3) Incorrect wiring of the M-NETtransmission line on the outdoorunit.
Disconnected wire for the MA remote controller or disconnected line to the terminal block.
The indoor transmission line is connected incorrectly to the transmission terminal block for centralized controller (TB7).
The male power supply connectors on the multiple outdoor units are connected to the female power supply switch connector
In the system to which the power supply unit for transmission lines is connected, the male power supply connector is connect-
ed to the female power supply switch connector (CN40) on the outdoor unit.
4) Disconnected M-NET transmission line on the indoor unit side.
5) Disconnected wire between the terminal block for M-NET line (TB5) of the indoor unit and the indoor unit board (CN2M) or
disconnected connector.
3. Check method and remedy
When 2) and 3) above apply, check code 7102 will be displayed on the self-diagnosis LED.
Same symptom for all units in a
system with one outdoor unit?
Check the
self-diagnosis LED
Is the error code 7102
Check item 1) in the
"Cause" column.
Check items 2) and 3)
in the "Cause" column.
Correct the error.
- 252 -
Measure voltages of the
terminal block for transmission
line (TB5) on the indoor unit.
Check item 4) in the
17 - 30V?
"Cause" column.
Check item 5)
in the "Cause" column.
Error found?
Indoor unit board or
MA remote controller failure

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