Daewoo KOR-63DB9S Printed Circuit Board, Circuit Check Procedure, Low Voltage Transformer check

PRINTED CIRCUIT BOARD

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
4-8	AC 25.8 V	AC 31.8 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 14	-5 VDC
2	IC 1 PIN 22

T:20ms(50Hz)

3

IC 1 PIN 1 OR 2

T:250ns(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, D9, 10, 11	NO LOAD

NOTE :

Each measure point must be measured with GND points.

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