Samsung UD26B1C2, UD18B1C2 Fault Diagnosis by Symptom, No Power completely dead-Initial diagnosis

3-3 Fault Diagnosis by Symptom

3-3-1 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

Remove power cord and plug in

again in approx. 5 seconds

YES

Replace

PCB display

Is operation lamp blinking?

	NO				YES
Is DC voltage of PCB		Does operation start when
		run/stop button on the remote
display normal?
		controller unit pushed?
	NO			NO
Is rating voltage ±10%		Is transmission display of the
range applied to the		remote controller unit blinking?
primary side (~,~)					YES
of the “BD71”
		Is "beep"sound heard from the
	NO
				main unit?
	NO
•Check linkage between					YES
power cord and		Is DC voltage of the PCB module
terminal tap				normal?
•Check fuse					YES
		5VDC Is voltage of #60 (indoor fan)
Is 14~18VAC	appear in	of the micom normal?
the secondary side (+, -)
of “BD71”		DC5V
NO	YES		10ms
				NO

YES	Normal
NO	Refer to remote control
	unit fault diagnosis

NO	Replace PCB module.
YES	DC12V
	Is voltage at SS71(indoor fan)
	YES	NO

Check connections

compressor 4-way

Replace RY71,

Replace

valve, outdoor fan and

RY73, RY72 and

SMPS PARTS

indoor fan.

SS71

NO

Replace resonator (X301)

Is operation normal?

Is output voltage of ICO2 normal?

Is voltage at #52 terminal of the		YES	NO
micom normal?
	Check PCB pattern.		Replace ICO2
10ms	Replace main PCB.
YES	NO
	Is voltage output		terminal of
Are voltage at #48 and #49 of the	TLP180(PC02) normal?
micom normal?
		YES	NO
250ns	OK	Replace TLP180(pc02)
YES

YES

OK

NO

Replace micom

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