Fault Diagnosis By Symptom; No Power - Samsung AQ07A1VE Service Manual

5-2 Fault Diagnosis by Symptom

5-2-1 No Power (completely dead)-Initial diagnosis
1) Checklist :
(1) Is input voltage normal?
(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
YES
Is DC voltage of PCB
display normal?
Is rating voltage ±10% range
Replace PCB
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
5-2
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 unit pushed?
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
normal?
Are voltages of #62, #36:SH07/09/12YAB,
SH09/12YAO(compressor), #60, #48:SH07/09/12YAB,
SH09/12YAO(4 way valve) and #61, #37:SH07/09/12YAB,
SH09/12YAO(outdoor fan) of the micom normal? 5VDC
Is voltage of #63 (indoor fan) of the micom normal?
DC5V
10ms
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
normal?
Are voltage at #30 and #31 of the
micom normal?
NO
Replace
NO
micom
YES
YES
NO
NO Refer to remote control
YES
unit?
YES
NO
YES
Are voltages at RY71(Compressor)
RY73(4-way valve) and SY72(outdoor fan)
YES
normal? DC12V
Is voltage at SS71(indoor fan)
NO
Check connections
compressor 4-way
0VDC
valve, outdoor fan
5VDC
and indoor fan.
YES NO
Is output voltage of ICO2 normal?
Check PCB pattern.
Replace main PCB.
20ms
YES
NO
100ns
YES
Normal
unit fault diagnosis
Replace PCB
module.
YES NO
Replace
RY71, RY73,
RY72 and
SS71
NO
YES
Replace ICO2
Is voltage output terminal of
D101~D105(IN4007) normal?
YES NO
Replace IN4007
OK
Samsung Electronics