Daewoo KOM-9P2CBS, Service Manual

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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
NOTE :
Each measure point must be measured with GND points.
NOTE :
1. Refer to Ciruit 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
6-7, 7-8
9-10
LOAD
DC 12V
AC 3.4V
NO LOAD
AC 26.0V
AC 4.0V
PRINTED CIRCUIT BOARD
NO CHECK POINT REMARK
1 IC1 PIN 63, 64 5VDC
2 IC1 PIN 38
3 IC1 PIN 33 OR 34
• Check method
1 MP1 DC 5V±0.25V Replace Q9, ZD2, EC2, R21, C3 NO LOAD
2 MP2 DC 12V±2.0V Replace D12, D13, EC4, EC5, R22,C7 NO LOAD
NO MEASURE POINT WAVE FORM REMEDY REMARK
T
T:20ms(50Hz)
5V
0V
T
T:250ns(4MHz)
5V
0V