Daewoo KOR-1N4A9W, Service Manual, Page: 26 / 34

25
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
2. Voltage Check
- Key check point
- Check method
NOTE
1. Refer to Circuit Diagram.
2. Secondary side voltage of the low voltage transformer changes in proportion to fluctuation of power source
oltage.
3. The allowable tolerance of the secondary voltage is within ± 5% of nominal voltage.
NOTE
Each measure point must be measured with GND points.
Terminal Voltage
(4,5) -6 or (7, 8) -6
LOAD
DC 12V
NO LOAD
AC 30 V
NO CHECK POINT REMARK
1 IC 1 PIN 5 5 VDC
2 IIC 1 PIN 8
3 IC 1 PIN 19 OR PIN 20
T:20ms(50Hz)
T:250ns(4MHz)
NO MEASURE POINT WAVE FORM REMEDY REMARK
1 MP1 DC 5V ±0.25V Replace Q8, R28, ZD3, C2, EC1 NO LOAD
2 MP2 DC 15V ±3.0V Replace EC3, D11, D12, D13, C9 NO LOAD