Daewoo KOR-6L4B5S69, Service Manual, Page: 27 / 35

26
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
NO CHECK POINT REMARK
1 IC 1 PIN 5 5 VDC
2 IC 1 PIN 8
3 IC 1 PIN 19 OR PIN 20
NOTE :
Each measure point must be measured with GND points.
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.
Terminal Voltage
(4,5)-6 or (7,8)-6
LOAD
AC 14 V
NO LOAD
AC 17 V
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 ±2.0V Replace EC3, D11, D12, D13 NO LOAD
PRINTED CIRCUIT BOARD
T
T:20ms(50Hz)
5V
0V
T
T:250ns(4MHz)
5V
0V