Mitsubishi Electric PQHY-P72ZLMU-A Service Handbook page 327

[ IX Troubleshooting ]
(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
work is performed ac-
cording to wiring
specifications.
Check that the
grounding work is
performed according
to grounding specifi-
cations.
2) Check the followings when the error "6607" occurs, or "HO" appears on the display on the remote controller.
Error code definition
7. The farthest distance of transmission line is
200m [656ft] or longer.
8. The types of transmission lines are different.
9. Heat source 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.
HWE15150
Error code definition
1. The transmission line and
the power line are not
wired too closely.
2. The transmission line is
not bundled with that for
another systems.
3. The specified wire is used
for the transmission line.
4. When the transmission
line is daisy-chained on
the indoor unit terminals,
are the shields daisy-
chained on the terminals,
too?
5. Is the shield of the indoor-
heat source transmission
cable grounded to the
earth terminal on the heat
source unit?
6. Check the treatment meth-
od of the shield of the
transmission line (for cen-
tralized control).
Isolate the transmission line from the power line (5cm [1-31/32"] or
more). Do not insert them in the same conduit.
The transmission line must be isolated from another transmission
line.
When they are bundled, erroneous operation may be caused.
Use the specified transmission line.
Type: Shielded wire CVVS/CPEVS/MVVS (For ME remote control-
ler)
2
Diameter: 1.25mm [AWG16] or more
(Remote controller wire: 0.3 - 1.25mm
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.
Connect the shield of the indoor-heat source transmission cable to
the earth terminal ( ) on the heat source unit.
If no grounding is provided, the noise on the transmission line can-
not escape leading to change of the transmission signal.
The transmission cable for centralized control is less subject to
noise interference if it is grounded to the heat source unit whose
power jumper cable was moved from CN41 to CN40 or to the pow-
er supply 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 heat source 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 heat source units.
Check that the farthest distance from the heat source unit to the in-
door 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-
ler)
2
Diameter: 1.25mm [AWG16] or more
(Remote controller wire: 0.3-1.25mm
Replace the heat source 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).
- 318 -
Remedy
2
[AWG22-16])
Remedy
2
[AWG22-16])
GB