Fault Diagnosis By Symptom; Samsung Electronics - Samsung AQ12A5(6)MB 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) 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 primary side(~,~)
display
of the "BD71"
•Check linkage between
power cord and
terminal tap
•Check fuse
Is 325VDC appear in the
secondary side (+, -)
of "BD71"
NO
Replace
SMPS PARTS
Replace resonator (X301)
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
ON/OFF 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
Are voltages of #8 (compressor),
#7(4 way valve) and #6 (outdoor fan)
of the micom normal? 5VDC
Is voltage of #60 (indoor fan) of the
micom normal?
DC5V
YES
Is voltage at #50 terminal of the Micom normal?
Is voltage at #18 terminal of the Micom normal?
Is voltage at #52 terminal of the micom
Are voltage at #48 and #49 of the
micom normal?
NO
NO
YES
YES
NO
NO
YES
unit?
YES
NO
normal?
YES
YES
10ms
NO
0VDC
5VDC
NO
YES
normal?
10ms
YES
NO
250ns
YES
Replace
micom
Normal
Refer to remote control
unit fault diagnosis
Replace PCB
module.
Are voltages at RY71(Compressor)
normal? DC12V
Is voltage at SS71(indoor fan)
YES NO
Check connections Replace
compressor RY71 and
and indoor fan. SS71
Is output voltage of ICO2 normal?
NO
YES
Check PCB pattern.
Replace ICO2
Replace main PCB.
Is voltage output terminal of
TLP180(PC02) normal?
YES NO
Replace TLP180(pc02)
OK

Samsung Electronics