Mitsubishi Electric AE-200A Service Handbook page 74

[V Troubleshooting]
(3) Check and solution
If noise is confirmed in the waveform or any of the errors of the error codes in (1) occur, perform the following checks.
Error description
1. Are the transmission line and power cable
(100—240VAC) routed together?
2. Is the transmission line bundled together
with the transmission line of another
system?
3. Is the specified cable being used for the
transmission line?
4. When the transmission line is
daisy-chained on
the indoor unit terminals, is the shield
daisy-chained too?
5. Is the transmission line grounded with the
earth?
6. Is the transmission line connected to the
junction terminals properly?
1. When the transmission line is
daisy-chained, is the shield daisy-chained
too?
2. Check the treatment method of the shield
of the
transmission line (for centralized control).
If the peak value is low, if a 66xx error occurs, or if the remote controller remains in the initial screen display state
Error description
1. The distance to the farthest end of transmission
line exceeds 200 m (656 ft).
2. The types of transmission lines differ.
3. Outdoor unit board failure
4. Indoor unit or remote controller failure
5. The MA remote controller is connected to the
M-NET transmission line.
NOTE:
For details on the restrictions on wiring length, refer to "III [4] Restrictions and notes on transmission wiring."
Lay the power cable as far away as possible. When laying the
cables over a long distance, provide a space of at least 5 cm
between them.
In particular, do not insert them in the same conduit.
Lay the transmission line so that it is separate from other
transmission lines.
When it is bundled with another transmission line, there is the risk of
erroneous operation.
Use the specified transmission line.
Transmission line type CVVS/CPEVS/MVVS shielded cable
(for M-NET remote controller)
Transmission line diameter
(Remote controller wire: 0.5 to 1.25 mm
The two wires of the transmission line are daisy-chained. The shield
must also be daisy-chained in the same way as the transmission
lines.
If the shield is not daisy-chained, its effect on reducing noise will be
small.
Prevent parts from being grounded with the earth.
If bare wires are twisted together, connect the wires properly by, for
example, crimping them together.
Ground one point of the shield at a unit that supplies power.
If no grounding is provided, the noise on the transmission line cannot
escape so there is the risk that the transmission signal will be
transformed.
The transmission line for centralized control is less susceptible to
noise interference if it is grounded from one outdoor unit in the case
of group operation between units with different refrigerant or from the
system controller in the case of using a system controller.
However, the environment against noise varies depending on the
distance of the transmission lines, the number of the connected
units, the type of the controllers to be connected, and the
environment of the installation site, so check that the transmission
line work for centralized control has been performed as follows.
a) When not grounded
・ Group operation between units with different refrigerant
Grounded at one outdoor unit (power supply unit)
・ Using system controller
Grounded at a power supply unit (including a system
controller with a built-in power supply)
b) When an error occurs even though grounded at one point
Ground the shield at all outdoor units and power supply
units (including system controllers with a built in power
supply)
Check that the distance from the outdoor unit or power supply unit to
the indoor unit and to the remote controller at the farthest end is 200
m (656 ft) or less.
Use the specified transmission line.
Transmission line type: CVVS/CPEVS/MVVS shielded cable
Transmission line diameter: At least 1.25 mm
2
wire: 0.5 to 1.25 mm )
Replace the outdoor unit control board or transmission power supply
board.
Replace the indoor unit control board or remote controller.
Connect the MA remote controller to the MA remote controller
terminal block (TB15) on the indoor unit control board.
70
Action
2
At least 1.25 mm
2
Action
2
(remote controller
)