
5-6
Samsung Electronics
5-4 PCB Inspection
5-4-1 Inspection Precautions
1) Be sure to check whether the AC sub power switch is removed when removing the main PCB or
panel PCB.
2) Do not hold the outside of the main PCB or panel PCB with the hand or aply excessive force to it.
3) When connecting or removing the connector to the main PCB or panel PCB, do not pull the lead
w i re, but hold the entire assembly with the hand.
5-4-2. Inspecting procedures
1) When there is any trouble with the main PCB or panel PCB, check the connector for a poor con-
necting and the PCB or copper-clad pattern for separation.
2) The PCB is composed of the following two parts.
• Main PCB: The main PCB is composed of the MICOM and peripheral circuit, relay drive sensor
drive circuit, DC 5V power circuit, DC 12V power circuit and buzzer drive circuit, etc.
• Panel PCB: The panel PCB is composed of the LED display key and remote contro l .
5-4-3. Detailed inspection procedures
NO NO NO NO
1 Turn off the sub power switch, 1) Is the fuse blown? 1) Overvoltage?
and then check PCB fuse. 2) Indoor fan motor short?
2 1. Apply the supply voltage Check the supply voltage 1) Power cord faulty, poor connection
2. When power lamp and LED display 1) Is the voltage between both of indoor and outdoor unit, fuse
operate afterpressing the on/off ends/of the trans connector(GT4,5 blown, wrong wiring of power cables.
button, it is not related to items AC187V ~ AC 253V? 2) Power trans faulty power circuit
1)~4). 2) The voltage between both faulty.
terminals/of the CN11 AC 18V~AC 3) Power circuit faulty load short.
21V. 4) Power circuit faulty, load short.
3) Is the voltage between both
terminals/of the REG1 (KA 7812)
out and GND DC 12V?
4) Is the voltage between both
terminals/of the REG2 (KA7805)
out and GND DC 5V?
3 Set the unit to “cool” operation mode 1) The compressor does 1) The relay(RY1) for driving the
by the “on/off” button and mode not operate. electronic contractor does not
selector key. operate.
1. Fan operation 2) Electronic contactor faulty.
2. Fan speed high, medium, low.
4 Set the unit to “fan” operation mode 1) Is AC 220V applied between the 1) Indoor fan motor faulty.
by the “on/off” button and mode com terminal and the high, medium, 2) Starting condenser faulty.
selector key. and low terminal at the indoor fan
1. Fan operation motor connector? (when selecting
2. Fan speed high, each fan speed)
medium, low. 2) Indoor fan motor does not turn.
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