Daewoo KOG-373R0S PRINTED CIRCUIT BOARD KOG-374R0S, KOG-375R0S, Circuit Check Procedure

PRINTED CIRCUIT BOARD <KOG-374R0S, KOG-375R0S>

1. CIRCUIT CHECK PROCEDURE

1. Low Voltage Transformer check

•The low voltage transformer is located on the P.C.B.

•Measuring condition: input voltage : 230V/Frequency : 50Hz

Terminal Voltage	LOAD	NO LOAD
4-7	AC 25.8 V	AC 28.4 V

NOTE :

1.Refer to Circuit Diagram (point 4).

2.Secondary side voltage of the low voltage transformer changes in proportion to fluctuation of power source voltage.

3.The allowable tolerance of the secondary voltage is within ± 5% of nominal voltage.

2.Voltage check

• Key check point

NO	CHECK POINT				REMARK
1	IC 1 PIN 2, 21, 30, 34				–5 VDC
2	IC 1 PIN 35
		0V					T:20ms(50Hz)
		–5V
			T
3	IC 1 PIN 31 OR 32
		0V
		–5V	T				T: 250 ns (4MHz)
• Check method
NO	MEASURE POINT	WAVE FORM				REMEDY		REMARK
1	MP1	DC -5V±0.25V			Replace VL1, EC1			NO LOAD
2	MP2	DC -12V±2.0V		Replace EC2, D6, D11, D12				NO LOAD

NOTE :

Each measure point must be measured with GND points.

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