26
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 Circuit Diagram.
2. Secondary side voltage of the low voltage transformer changes in proportion to fluctuation of power source volt-
age.
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
5-6-7
LOAD
AC 12.6 V
NO LOAD
AC 14.7 V
NO
CHECK POINT
REMARK
1
IC1 PIN 5
5VDC
2
IC1 PIN 8
3
IC1 PIN 35 OR PIN 36
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, D13, D14
NO LOAD
T
T : 16.67ms(60Hz)
5V
0V
T
T : 250 ns(4MHz)
5V
0V
