25
D How to check miswiring and serial signal error
A
• Reinstall ei-
ther the unit
or the light
away from
each other.
• Attach a
fi
lter
on remote
control
receiving
section of
the indoor
unit.
• Turn OFF inverter-controlled lighting
equipment.
• Turn OFF the power supply and then
turn ON again.
• Press the emergency operation switch.
After the relay
52C is turned on
3 minutes later, is
miswiring or the
serial signal error
indicated?
No
B
Yes
1 Make sure that the wiring is correct. If the pro-
cedure is performed without correcting miswir-
ing, it may lead to damage to the P.C. board.
3 Be sure to release the failure-mode recall function after checking.
Turn OFF the power supply.
Is there rated voltage in the
power supply?
Yes
No
1. Turn ON the power supply.
2. Press the emergency operation switch.
Check the power supply.
Has the relay 52C been turned on 3 minuets later ?
[The relay will be turned on in 3 to 7 seconds by
bridging the timer short mode point (Refer to 10-7.).]
Is there any miswiring, poor
contact, or wire disconnec-
tion of the indoor/outdoor
connecting wire?
Yes
No
Correct them.
No
Yes
Aim the remote controller at the indoor unit, and press
STOP/OPERATE/ (OFF/ON) button. The relay 52C will
be turned on, and the outdoor unit will be energized.
Is the rated supply voltage applied
between the S1 and S2 on the
outdoor terminal block? (Check of
supply voltage)
No
Is there any problem in the
indoor/outdoor connecting wire,
such as the damage of the wire,
intermediate connection, poor
contact with the terminal block?
Yes
Replace
the indoor/
outdoor con-
necting wire.
No
Replace the indoor electronic control
P.C. board. 3
Is there approximately 250 VDC – 370
VDC between DB61 (+) and DB61
(–) on the inverter P.C. board in the
outdoor unit? (Voltage check of the
inverter P.C. board in the outdoor unit)
No
Replace the
inverter P.C.
board in the
outdoor unit. 2
Yes
Yes
Does the LED on the inverter P.C.
board in the outdoor unit repeat
"3.6-second-OFF and 0.8-second-
ON quick blinking" for 3 minutes
after the outdoor unit is energized?
(Check the blinking pattern within 3
minutes after LED is turned on. Af-
ter 3 minutes, LED will blink 6 times
whether the inverter P.C. board in
the outdoor unit is normal or not.)
No
Replace the
inverter P.C.
board in the
outdoor unit. 2
Yes
A
2 Be careful of 140
VDC – 280 VDC
residual charge in
the capacitor on the
main inverter circuit.
B
Turn OFF the power supply. Make sure again that the
indoor/outdoor connecting wire is correctly connected.
With the indoor/outdoor connecting wire connected, bridge
between S2 and S3 on the outdoor terminal block. 1
<Preparation of the remote controller>
While pressing both OPERATION SELECT button and
TOO COOL button on the remote controller at the same
time, press RESET button.
First, release RESET button.
Hold down the other 2 buttons for another 3 seconds.
Make sure that the indicators on the LCD screen shown in
the right
fi
gure are all displayed. Then release the buttons.
(Setting up the failure mode recall function)
Indication of miswiring
Indication of serial signal error
OPERATION
INDICATOR lamp
Continuous blinks
Initializing the determination of the power
receiving system
The microprocessor may have mistaken the
unit as a model receiving power from the
outdoor unit. Follow the procedure below to
start the determination of the power receiv-
ing system all over again.
1. Hold down the emergency operation
switch for 30 seconds. (Do not release the
switch even though a buzzer beeps once
in about 5 seconds. Keep holding down
the switch until a buzzer beeps again for
1 second after 30 seconds. Figure 1)
2. Turn off the power supply.
3. Wait for about 30 seconds.
4. Turn on the power supply.
5. Press the emergency operation switch.
6. The relay 52C will be turned on in 3 min-
utes.
Has the miswiring or the serial error
been indicated?
Yes
No
ON
OFF
Buzzer
0.5-second
1-second
ON
OFF
Emergency
operation switch
30-second
ON
OFF
5-second
Beeps
Beeps
Beeps
Figure 1
OBH750
