Daewoo KOC-9U0T7S, Service Manual

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12. PRINTED CIRCUIT BOARD
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. Secondary side voltage of the low voltage transformer changes in proportion to fluctuation of power source
voltage.
2. The allowable tolerance of the secondary voltage is within 5% of nominal voltage.
NOTE: Each measure point must be measured with GND points.
Terminal
6-10
Voltage(load)
AC 12.4 V
Voltage(no load)
AC 13.3 V
NO CHECK POINT REMARK
1 IC1 PIN 2, 3, 4 5VDC 5%
2 IC1 PIN 15
3 IC1 PIN 17 OR 18
T : 20 ms(50Hz)
5V
0V
T
T : 250 ns(4MHz)
5V
0V
T
NO MEASURE POINT WAVE FORM REMEDY REMARK
1 MP1 DC 5V 5% NO LOAD
2 MP2 DC 12V 20% NO LOAD
3
10
6
5
Replace VL1, EC1, C4, C5
Replace D17-20, EC2, R28, R29, D15, D7