Printed Circuit Board; Circuit Check Procedure - Daewoo KOR-1N9Z9S25 Service Manual

PRINTED CIRCUIT BOARD

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
(4,5)-6 or (7,8)-6
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 5
2 IC 1 PIN 8
3 IC 1 PIN 35 OR PIN 36
• Check method
NO MEASURE POINT
1 MP1
2 MP2
NOTE :
Each measure point must be measured with GND points.
LOAD
AC 25.3 V
5 VDC
5V
0V
5V
0V
T
WAVE FORM
DC 5V ±0.25V
DC 15V ±2.0V
24
REMARK
T
REMEDY
Replace VL1, EC1
Replace EC2, D11, D13, D14
NO LOAD
AC 30.8 V
T: 20ms (50Hz)
T: 250ns (4MHz)
REMARK
NO LOAD
NO LOAD