Daewoo KOG-371G0S Service Manual page 78

PRINTED CIRCUIT BOARD <KOG-373R0S, KOG-393R0S>
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
4-7
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
1 IC 1 PIN 2, 21, 30, 34
2 IC 1 PIN 35
3 IC 1 PIN 31 OR 32
• Check method
NO MEASURE POINT
1
2
NOTE :
Each measure point must be measured with GND points.
WAVE FORM
MP1 DC -5V±0.25V
MP2 DC -12V±2.0V
LOAD
AC 25.8 V
REMARK
–5 VDC
0V
–5V
T
0V
–5V
T
Replace EC2, D10, D11, D12
77
NO LOAD
AC 28.4 V
T:20ms(50Hz)
T: 250 ns (4MHz)
REMEDY
Replace VL1, EC1
REMARK
NO LOAD
NO LOAD