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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: 120V / Frequency: 60Hz
2. Voltage Check
- Key check point
- Check method
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.
NOTE
Each measure point must be measured with GND points.
Terminal Voltage
6-8
9-10
LOAD
DC 12V
AC 3.4V
NO LOAD
AC 25.8V
AC 4.0V
NO CHECK POINT REMARK
1 IC1 PIN 63, 64 5VDC
2 IC1 PIN 38
3 IC1 PIN 33 OR 34
T : 16.67ms(60Hz)
5V
0V
T : 250 ns(4MHz)
5V
0V
NO MEASURE POINT WAVE FORM REMEDY REMARK
1 MP1 DC 5V±0.25V Replace Q8, ZD3, EC2 NO LOAD
2 MP2 DC 12V±2.0V
Replace D12, 13, R25, EC5, EC4
NO LOAD