Trouble shooting
Si04-115
80
Service Diagnosis
5.14
Faulty Outdoor Unit PCB and Transmitting/Receiving
Circuit
Remote
Controller
Display
∗
Outdoor unit LED
Display
A
3
3
3
3
Method of
Malfunction
Detection
1. The proper program operation of the microcomputer is checked by the program.
2. Signals transmitted from the outdoor unit to the indoor unit are received by the outdoor unit
itself in indoor unit -outdoor unit signal transmission mode, and proper receiving of the
signals by the indoor unit is checked.
Malfunction
Decision
Conditions
1. When the microcomputer program does not function properly.
2. When the signals transmitted from the outdoor unit to the indoor unit are received by the
outdoor unit itself in indoor unit-outdoor unit signal transmission mode, but not properly.
3. When the zero cross signal is not detected over 10 seconds.
Supposed
Causes
"
Display disabled by faulty power supply.
"
Microcomputer program run-away due to an external factor.
∗
Noise
∗
Momentary voltage drop
∗
Momentary power failure, etc.
"
Faulty outdoor unit PCB.
Troubleshooting
Check No.13
Refer to P.91
Is the grounding proper?
Is there any disturbance?
Is it normal?
NO
NO
NO
NO
Turn off the power,
remove No. 2 of the terminal board,
and turn the power on again.
Check the grounding.
Turn the power off and back on again.
Does
the same LED indication
appear again?
YES
YES
YES
YES
Correct the power supply.
∗
Check the voltage at the terminals
marked with "5V" and "GND".
Replace the outdoor unit PCB.
Provide the grounding.
The malfunction may be caused by an
external factor, rather than defective parts.
Locate the cause of the noise, etc.,
and correct the situation.
Locate the cause of the power supply
waveform disturbance, and take
necessary measures.
Replace the outdoor unit PCB.
Replace the indoor unit PCB.
(R1958)
Check No. 13
Power supply waveform check
YES
NO
Check the 5-VDC power supply of
the outdoor unit PCB.
Is the voltage 5 ± 0.5 V?
Check the power supply voltage.
YES
NO
Is it at the rated voltage?
Caution
Be sure to turn off power switch before connect or disconnect connector,
or parts damage may be occurred.
