8
3-2 Fault Diagnosis by Symptom
3-2-1 No Power(completely dead)-Initial diagnosis
1) Checklist :
(1) Is input voltage normal?
(2) Is AC power linked correctly?
(3) Is output voltage of DC regulator IC KA7812(IC01) normal? (11.5VDC-12.5VDC)
(4) Is output voltage of DC regulator IC KA7805(IC02) normal? (4.5VDC-5.5VDC)
2) Troubleshooting procedure
Replace PCB
display
Is DC voltage of PCB dis-
play normal?
Remove power cord and plug in again
in approx. 5 seconds
Is operation lamp blinking?
Does operation start when run/stop
button on the remote controller unit pushed?
Is transmission display of the remote
controller unit blinking?
Is "beep"sound heard from the main
unit?
Is DC voltage of the PCB module
normal?
Are voltages of #62 (compressor), #61
(outdoor fan) of the micom normal? 5VDC
Is voltage of #63 (indoor fan) of the micom
normal?
Is voltage at #32 terminal of the Micom normal?
0VDC
Is voltage at #64 terminal of the Micom normal?
5VDC
Is rating voltage ±10% range
applied to the primary side
of the power transformer?
¥Check linkage between
power cord and
terminal tap
¥Check fuse
Is 14~18VAC appear in the
secondary side of the
power transformer?
Replace power
transformer
YES
NO
YES
NO
YES
YES
YES
NO
YES
YES
YES
DC5V
10ms
10ms
100ns
NO
NO
OK
YES
YES
YES
YES
NO
NO
YES
Normal
Refer to remote control
unit fault diagnosis
Replace PCB
module.
Is output voltage of ICO2 normal?
Check connections
compressor, outdoor
fan and indoor fan.
Are voltages at RY71(Compressor)
RY72(outdoor fan) normal? DC12V
Is voltage at SS71(indoor fan)
Replace RY71,
RY73, RY72 and
SS71
NO
NO
NO
Is voltage output terminal of
D101~D105(IN4007) normal?
Replace ICO2
Check PCB pattern.
Replace main PCB.
Replace IN4007
Replace
micom
Is voltage at #25 terminal of the micom
normal?
Are voltage at #30 and #31 of the
micom normal?
NO
NO
NO
YESNO
NO
NO
YES
OK
Is operation normal?
Replace resonator (X501)
1- 4/17/01 4:41 PM Page 8
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