Service manual

33
12. PRINTED CIRCUIT BOARD (KOC-1B5K)
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. Secondary side voltage of the low voltage transformer changes in proportion to fluctuation of power source
voltage.
2. The allowable tolerance of the secondary voltage is within ± 5% of nominal voltage.
NOTE: Each measure point must be measured with GND points.
: The marks of the above corresponding voltage (+5V, +24V) are written on the PCB.
Terminal
6-7
8-9
9-10
Voltage(olad)
AC 17.0 V
AC 1.3 V
AC 1.3 V
Voltage(no load)
AC 19.9 V
AC 1.6 V
AC 1.6 V
NO CHECK POINT REMARK
1 IC1 PIN 63, 64 5VDC±5%
2 IC1 PIN 38
3 IC1 PIN 33 OR 34
T : 16.67 ms(60Hz)
5V
0V
T
T : 250 ns(4MHz)
5V
0V
T
NO MEASURE POINT WAVE FORM REMEDY REMARK
1A DC 5V±5% Replace ZD2, EC1 NO LOAD
2B DC 24V±20% Replace D20-23, EC6 NO LOAD