Fault Diagnosis By Symptom - Samsung AQ18A6RC Service Manual

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
YES
Is DC voltage of PCB
display normal?
Is the input rating
Replace PCB
range applied to the
display
between #1 and #3 of CN78
¥Check linkage between
power cord and
terminal tap
¥Check fuse
Is 11~12.5VAC appear in
the input side of the DC
regulator IC KA7805(ICO2)?
NO
Refer to replace
PCB Module
Replace resonator (X501)
Is operation normal?
YES
OK
8
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
±10%
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
DC5V
YES
Is voltage at #33 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
NO
NO
YES
YES
NO
NO
YES
unit?
YES
NO
normal?
YES
YES
micom normal?
10ms
NO
; 0VDC
; 5VDC
NO
YES
normal?
10ms
NO
YES
micom normal?
100ms
YES
Replace
micom
Normal
Refer to remote control
unit fault diagnosis
Refer to Replace
PCB module.
Are voltages at RY71(Compressor)
RY73 (4 way valve) and RY 72 (Outdoor fan)
normal? (DC12V)
Is voltage at SS71(indoor fan)
YES
Check connections Replace
compressor 4-way RY71, RY73,
valve, outdoor fan and RY72 and
indoor fan.
Is output voltage of ICO2 normal?(DC5V)
YES
Check PCB pattern. Module
Replace ICO2
Refer to Replace module PCB.
Is voltage output terminal of
D101~D105(IN4007) normal?
YES NO
OK Replace IN4007
NO
SS71
NO