26
D How to check miswiring and serial signal error
• Turn OFF inverter-controlled lighting
equipment.
• Turn OFF the power supply and then
turn ON again.
• Press the emergency operation switch.
A
Is serial signal
error indicated 6
minutes later?
B
Yes
• Reinstall
either the unit
or the light
away from
each other.
•
Attach a filter
on remote
control receiv-
ing section
of the indoor
unit.
No
Replace the indoor power
P.C. board and the indoor
terminal P.C. board
Turn OFF the power supply.
Is there rated voltage in the power supply?
Yes
No
Turn ON the power supply.
Check the power supply.
Is there rated voltage between outdoor terminal block S1 and S2?
No
Check the wiring.
Press the emergency operation switch once.
Does the OPERATION INDICATOR lamp light
up? <Confirmation of the power to the indoor
unit>
No
Is serial signal error indicated 6 minutes later?
Yes
No
Is there any miswiring, poor
contact, or wire disconnec-
tion of the indoor/outdoor
connecting wire?
Yes
Correct them.
No
A
Turn OFF the power supply.
Check once more if the indoor/outdoor
connecting wire is not miswiring.
Bridge the outdoor terminal block S2 and
S3. * 1
B
* 1. Miswiring may damage indoor electronic control P.C.
board during the operation.
Be sure to confirm the wiring is correct before the opera
-
tion starts.
Turn ON the power supply.
Does the LED on the inverter P.C. board or the outdoor electronic control P.C.
board repeat "3.6-second-OFF and 0.8-second-ON quick blinking"? * 3
Yes
No
(Lit or not
lit)
Replace the inverter P.C. board or the outdoor
electronic control P.C. board. * 2
* 2. Be careful of the residual voltage of smoothing
capacitor.
Is there amplitude of 10 to 20 V DC between indoor terminal block S2
and S3? <Confirmation of serial signal>
Yes
Check the wiring
If there are any error of the indoor/outdoor connecting wire:
such as the damage of the wire, intermediate connection,
and/or poor contact to the terminal block, replace the indoor/
outdoor connecting wire.
No
Is there 2 V DC or less between CN10A (+)
and JPG (GND)(-) on the indoor electronic
control P.C. board?
No
Yes
* 3. Be sure to check this within 3 minutes after turning ON.
After 3 minutes, LED blinks 6 times. Even when the
inverter P.C. board or the outdoor electronic control P.C.
board is normal, LED blinks 6 times after 3 minutes.
(Except for outdoor unit of multi system type)
Is there 2 V DC or less between
CN10A (+) and JPG (GND)(-) on
the indoor electronic control P.C.
board?
Is there 2 V DC or less between
CN10A (+) and JPG (GND)(-) on
the indoor electronic control P.C.
board?
Replace the indoor elec-
tronic control P.C. board.
No
Yes
No
Yes
Is the bus-bar voltage of the inverter P.C. board or the outdoor electronic control P.C. board normal? (Refer
to "TEST POINT DIAGRAM AND VOLTAGE" in the outdoor service manual.)
No
Yes
Check of power supply.
(Refer to the outdoor
service manual.)
Turn OFF the power supply.
Remove the bridge between outdoor terminal block S2 and S3.
Turn ON the power supply.
Is there rated voltage between indoor terminal block S1 and S2?
<Confirmation of power voltage>
Yes
No
Yes
Yes
MSZ-HM09/12/15NA
OBH746D
