Mitsubishi Electric PURY-HP72 Service Handbook page 276

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[8-4 Checking Transmission Waveform and for Electrical Noise Interference ]
(3) Check method and remedy
1) Measures against noise
Check the followings when noise exists on the wave or the errors described in (1) occur.
Check that the wiring
1. The transmission line and
work is performed ac-
cording to wiring
2. The transmission line is
3. The specified wire is used
4. When the transmission
Check that the
5. Is the shield of the indoor-
grounding work is
performed according
to grounding specifi-
6. Check the treatment meth-
2) Check the followings when the error "6607" occurs, or "HO" appears on the display on the remote controller.
Error code definition
The farthest distance of transmission line is
200m [656ft] or longer.
The types of transmission lines are different.
Outdoor unit circuit board failure
10. Indoor unit circuit board failure or remote con-
troller failure
11. The MA remote controller is connected to the M-
NET transmission line.
Error code definition
Isolate the transmission line from the power line (5cm [1-31/32"] or
the power line are not
more). Do not insert them in the same conduit.
wired too closely.
The transmission line must be isolated from another transmission
not bundled with that for
another systems.
When they are bundled, erroneous operation may be caused.
Use the specified transmission line.
for the transmission line.
Type: Shielded wire CVVS/CPEVS/MVVS (For ME remote control-
Diameter: 1.25mm
(Remote controller wire: 0.3 - 1.25mm
The transmission is two-wire daisy-chained. The shielded wire
line is daisy-chained on
must be also daisy-chained.
the indoor unit terminals,
When the shielded cable is not daisy-chained, the noise cannot be
are the shields daisy-
reduced enough.
chained on the terminals,
Connect the shield of the indoor-outdoor transmission cable to the
outdoor transmission ca-
earth terminal ( ) on the outdoor unit.
ble grounded to the earth
If no grounding is provided, the noise on the transmission line can-
terminal on the outdoor
not escape leading to change of the transmission signal.
The transmission cable for centralized control is less subject to
od of the shield of the
noise interference if it is grounded to the outdoor unit whose power
transmission line (for cen-
jumper cable was moved from CN41 to CN40 or to the power sup-
tralized control).
ply unit.
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, or the environment of the
installation site. Therefore, the transmission line work for central-
ized control must be performed as follows.
Check that the farthest distance from the outdoor unit to the indoor
unit and to the remote controller is within 200m [656ft].
Use the specified transmission line.
Type: Shielded wire CVVS/CPEVS/MVVS (For ME remote control-
Diameter: 1.25mm
(Remote controller wire: 0.3-1.25mm
Replace the outdoor unit control board or the power supply board
for the transmission line.
Replace the indoor unit circuit board or the remote controller.
Connect the MA remote controller to the terminal block for MA re-
mote controller (TB15).
- 265 -
[AWG16] or more
When no grounding is provided:
Ground the shield of the transmission cable by connecting to
the outdoor unit whose power jumper connector was moved
from CN41 to CN40 or to the power supply unit.
When an error occurs even though one point grounding is
provided: Ground the shield on all outdoor units.
[AWG16] or more

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