Pcb Inspection Method - Samsung AS18WJWB Service Manual

6-4 PCB Inspection Method

6-4-1 Pre-inspection Notices
1. Check if you pulled out the AC power plug when you eliminate the PCB or front panel.
2. Don't hold the PCB side not impose excessive force on it to eliminate the PCB.
3. Don't pull the lead wire but hold the whole housing to connect or disconnect a connector to the PCB.
6-4-2 Inspection Procedure
1. Check connector connection and peeling of PCB or bronze coating pattern when you think the PCB is broken.
2. The PCB is composed of the 3 parts.
G Main PCB Part : MICOM and surrounding circuit, relay, room fan motor driving circuit and control circuit, sensor driving circuit,
power circuit of DC12V and DC5V, and buzzer driving circuit.
G Display part : LED lamp
G Switch part : Switch
6-4-3 Detailed Inspection Procedure
No Procedure
1
Plug out and pull the PCB
out of the electronic box.
Check the PCB fuse.
Supply power.
2
If the operating lamp
twinkles at this time,
the above 1)~3) have
no relation.
3
Press the ON/OFF button
and operate TURBO
mode.
But, exclude the
RESERVE operation.
4 Press the ON/OFF button.
1. FAN Speed [High]
2. Continuous Operation
Samsung Electronics
Inspection Method
1) Is the fuse disconnected? (F701)
Checking the power voltage.
1) Is the DB71input voltage AC200V~AC240V?
2) Is the voltage between both terminals of the
C102 on the 2 nd side of the transformer AC12V
±0.5V?
3) Is the voltage between both terminals of OUT
and GND of IC02(KA78L05) DC5V ±0.5V?
Checking the power voltage.
1) Check the voltage of the relay(RY71) coil(IC05 PIN
#11 and GND : 0V, PIN#6 and GND : 5V) during
operation(3 minutes after TURBO operation).
2) Check the voltage of both terminals of
terminal block 1 and N1 after 3 minute
operation.: AC220V
1) Is the voltage over AC180V being imposed
on terminal #3 and #5 of the fan motor
connector(CN72)?
2) The fan motor of the indoor unit doesn't run.
3) The power voltage between terminal #3 and #5
of the connector(CN72) is 0V.
Cause
• Overcurrent
• Indoor Fan Motor Short
• AC Part Pattern Short of the MAIN PCB
• Power Cord is fault, Fuse open. Wrong
Power Cable Wiring, AC Part is faulty.
• Switching Trans or Power Circuit is faulty
• Power Circuit is faulty, Load Short
• Relay(RY71) Coil Disconnection, IC05 is
faulty
• Relay(RY71) Contact is faulty
• Fan Motor of the indoor is faulty
• Fan Motor Connector(CN72) is faulty
• ASS'Y Main PCB is faulty
• Connection is faulty
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