DAEWOO ELECTRONICS KOG-3C6R - Printed Circuit Board; Circuit Check Procedure

25
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
PRINTED CIRCUIT BOARD
NO CHECK POINT REMARK
1 IC 1 PIN 40, 18 5 VDC
2 IC 1 PIN 29
3 IC 1 PIN 15 OR 16
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.
T
5V
0V
T: 250 ns (4MHz)
T
Terminal Voltage
4-7
LOAD
DC 12 V
NO LOAD
AC 29.5 V
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, D10 NO LOAD
T:20ms(50Hz)
5V
0V
27