Mitsubishi Electric PUHY-HP120TNU-A, Service Handbook

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[8-4 Checking Transmission Waveform and for Electrical Noise Interference ]
16
- chapter 8 HWE18240_GB
8 Troubleshooting Based on Observed Symptoms
(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.
2) Check the followings when the error "6607" occurs, or "HO" appears on the display on the remote controller.
Error code definition Remedy
Check that the wiring
work is performed ac-
cording to wiring
specifications. 1. The transmission line and
the power line are not
wired too closely. Isolate the transmission line from the power line (5cm [1-31/32"] or
more). Do not insert them in the same conduit.
2. The transmission line is
not bundled with that for
another systems. The transmission line must be isolated from another transmission
line.
When they are bundled, erroneous operation may be caused.
3. The specified wire is used
for the transmission line. Use the specified transmission line.
Type: Shielded wire CVVS/CPEVS/MVVS (For ME remote control-
ler)
Diameter: 1.25mm
2
[AWG16] or more
(Remote controller wire: 0.3 - 1.25mm
2
[AWG22-16])
4. When the transmission
line is daisy-chained on
the indoor unit terminals,
are the shields daisy-
chained on the terminals,
too? The transmission is two-wire daisy-chained. The shielded wire
must be also daisy-chained.
When the shielded cable is not daisy-chained, the noise cannot be
reduced enough.
Check that the
grounding work is
performed according
to grounding specifi-
cations. 5. Is the shield of the indoor-
outdoor transmission ca-
ble grounded to the earth
terminal on the outdoor
unit? Connect the shield of the indoor-outdoor transmission cable to the
earth terminal (
) on the outdoor unit.
If no grounding is provided, the noise on the transmission line can-
not escape leading to change of the transmission signal.
6. Check the treatment meth-
od of the shield of the
transmission line (for cen-
tralized control). The transmission cable for centralized control is less subject to
noise interference if it is grounded to the outdoor unit whose power
jumper cable was moved from CN41 to CN40 or to the power sup-
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.
(1) 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.
(2) When an error occurs even though one point grounding is
provided: Ground the shield on all outdoor units.
Error code definition Remedy
7. The farthest distance of transmission line is
200m [656ft] or longer. Check that the farthest distance from the outdoor unit to the indoor
unit and to the remote controller is within 200m [656ft].
8. The types of transmission lines are different. Use the specified transmission line.
Type: Shielded wire CVVS/CPEVS/MVVS (For ME remote control-
ler)
Diameter: 1.25mm
2
[AWG16] or more
(Remote controller wire: 0.3-1.25mm
2
[AWG22-16])
9. Outdoor unit circuit board failure Replace the outdoor unit control board or the power supply board
for the transmission line.
10. Indoor unit circuit board failure or remote con-
troller failure Replace the indoor unit circuit board or the remote controller.
11. The MA remote controller is connected to the M-
NET transmission line. Connect the MA remote controller to the terminal block for MA re-
mote controller (TB15).