Mitsubishi Electric City Multi PQHY-P72 Service Handbook page 221

[ IX Troubleshooting ]
Error
Error definition and error detec-
Code tion method
6831 MA communication error or no
reception error
Communication between the
MA remote controller and the
indoor unit is not done proper-
ly. No proper data has been re-
ceived for 3 minutes.
6834 MA communication error or
start bit detection error
Communication between the
MA remote controller and the
indoor unit is not done proper-
ly.
No proper data has been re-
ceived for 2 minutes.
6832 MA communication error or
synchronization recovery error
Communication between the
MA remote controller and the
indoor unit is not done proper-
ly.
Failure to detect opening in the
transmission path and unable
to send signals
Indoor unit : 3 minutes
Remote controller : 6 seconds
6833 MA communication error or
transmission/reception H/W er-
ror
Communication between the
MA remote controller and the
indoor unit is not done proper-
ly.
An error occurs when the
transmitted data and the re-
ceived data differ for 30 times
in a row.
Cause
(1) Contact failure of the remote
controller lines of MA remote
controller or the indoor unit.
(2) All the remote controllers are set
to SUB.
(3) Failure to meet wiring regula-
tions
Wire length
Wire size
Number of remote controllers
Number of indoor units
(4) The remote controller is re-
moved after the installation with-
out turning the power source off.
(5) Noise interference on the re-
mote controller transmission
lines
(6) Faulty circuit that is on the in-
door board and performs trans-
mission/reception of the signal
from the remote controller
(7) Problems with the circuit on the
remote controller that sends or
receives the signals from the re-
mote controller
(1) Contact failure of the remote
controller lines of MA remote
controller or the indoor unit.
(2) 2 or more remote controllers are
set to MAIN.
(3) Overlapped indoor unit address
(4) Noise interference on the re-
mote controller lines
(5) Failure to meet wiring regula-
tions
Wire length
Wire size
Number of remote controllers
Number of indoor units
(6) Problems with the circuit on the
remote controller that sends or
receives the signals from the re-
mote controller
- 212 -
Check method and remedy
1) Check for disconnected or loose
transmission lines for the indoor units
or MA remote controllers.
2) Confirm that the power is supplied to
the main power source and the remote
controller line.
3) Confirm that MA remote controller's
capacity limit is not exceeded.
4) Check the sub/main setting of the MA
remote controllers.One of them must
be set to MAIN.
5) Diagnose the remote controller
(described in the remote controller in-
stallation manual).
[OK]: no problems with the remote
controller (check the wiring regula-
tions)
[NO]: Replace the MA remote control-
ler.
[6832, 6833, ERC]:
due to noise interference
<Go to (5)>
6) Check wave shape/noise on MA re-
mote controller line by following <4. In-
vestigation method of transmission
wave shape/noise>.
7) When no problems are found with
items 1 through 6, replace the indoor
unit board or the MA remote control-
ler.
The following status can be confirmed
on LED1 and 2 on the indoor unit
board.
LED1 is lit.
The main power source of the indoor
unit is turned on.
LED2 is lit.
MA remote controller line is being
powered.