27
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
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
4-7
LOAD
AC 12.6 V
NO LOAD
AC 14.7 V
NO
CHECK POINT
REMARK
1
IC1 PIN 2, 21, 30, 34
-5VDC
2
IC1 PIN 35
3
IC1 PIN 31 OR 32
T : 20.0ms(50Hz)
T : 250 ns(4MHz)
NO
MEASURE POINT
WAVE FORM
REMEDY
REMARK
1
MP1
DC -5V±0.25V
Replace VL1, EC1
NO LOAD
2
MP2
DC -12V±2.0V
Replace EC2, D12,13,14
NO LOAD
