Samsung US18A6RC, Service Manual

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8
3-2 Fault Diagnosis by Symptom
3-2-1 No Power(completely dead)-Initial diagnosis
1) Checklist :
(1) Is input voltage normal? (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 input voltage of DC regulator IC KA7805 (IC02) normal? (11VDC-12.5VDC)
(5) 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
display 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 #8 (compressor), and#6
(outdoor fan) of the micom normal? ; 5VDC
Is voltage of #60 (indoor fan) of the micom
normal?
Is voltage at #33 terminal of the Micom normal?
; 0VDC
Is voltage at #18 terminal of the Micom normal?
; 5VDC
Is the rating Voltage ±10%
range applied to the
between #1 and #3 of CN78
•Check linkage between
power cord and
terminal tap
•Check fuse
Is 11~12.5VDC appear in
the input side of the DC
regulator IC KA7805(IC02)?
refer to
replace
PCB module
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
Refer to Replace PCB
module.
Is output voltage of ICO2 normal?(DC5V)
Check connections
compressor, outdoor
fan and indoor fan.
Are voltages at RY71(Compressor)
and RY72 (Outdoor fan) normal? ; DC12V
Is voltage at SS71(indoor fan)
Replace
RY71, RY72
and SS71
NO
NO
NO
Is voltage output terminal of
D101~D105(IN4007) normal?
Replace ICO2
Refer to replace PCB
module
Replace IN4007
Replace
micom
Is voltage at #52 terminal of the micom
normal?
Are voltage at #48 and #49 of the
micom normal?
NO
NO
NO
YES NO
NO
NO
YES
OK
Is operation normal?
Replace resonator (X501)
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