Fault Diagnosis By Symptom - Samsung AS12A2VC Service Manual

3-2 Fault Diagnosis by Symptom

3-2-1 No Power(completely dead)-Initial diagnosis
1) Checklist :
(1) Is input voltage normal? (the rating voltage ±10% range.)
(2) Is AC power linked correctly?
(3) Are connections between primary side, secondary side of the power transformer and PCB good.
(4) Is output voltage of DC regulator IC KA7812 (IC01) normal? (11VDC-12.5VDC)
(5) Is output voltage of DC regulator IC KA7805 (IC02) normal? (4.5VDC-5.5VDC)
2) Troubleshooting procedure
Is DC voltage of PCB dis-
YES
play normal?
Is the rating voltage ±10%
Replace PCB
range applied to the
display
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?
NO
Replace power
transformer
Replace resonator (X501)
Is operation normal?
YES
OK
Remove power cord and plug in again
in approx. 5 seconds
Is operation lamp blinking?
NO
Does operation start when
run/stop button on the remote controller
NO
Is transmission display of the remote
controller unit blinking?
Is "beep"sound heard from the main
NO
NO
Is DC voltage of the PCB module
Are voltages of #62 (compressor), #60(4
way valve) and #61 (outdoor fan) of the
micom normal? 5VDC
Is voltage of #63 (indoor fan) of the
DC5V
YES
Is voltage at #32 terminal of the Micom normal?
Is voltage at #64 terminal of the Micom normal?
Is voltage at #25 terminal of the micom
Are voltage at #30 and #31 of the
NO
NO
YES
YES
unit pushed?
NO
NO
YES
unit?
YES
NO
normal?
YES
YES
micom normal?
10ms
NO
0VDC
5VDC
YES NO
normal?
10ms
YES
NO
micom normal?
100ns
YES
Replace
micom
Normal
Refer to remote control
unit fault diagnosis
Replace PCB
module.
Are voltages at RY71(Compressor)
RY73(4-way valve) and SY72(outdoor fan)
normal? DC12V
Is voltage at SS71(indoor fan)
YES
Replace
Check connections
RY71, RY73,
compressor 4-way
RY72 and
valve, outdoor fan and
indoor fan.
Is output voltage of ICO2 normal?
YES
Check PCB pattern.
Replace ICO2
Replace main PCB.
Is voltage output terminal of
D101~D105(IN4007) normal?
YES NO
Replace IN4007
OK
NO
SS71
NO
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