33
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
NO
CHECK POINT
REMARK
1
IC1 PIN 20, 21(KOC-922T9S/R)
5VDC 5%
IC1 PIN 26, 27(KOC-923T9S/R)
2
IC1 PIN 22 (KOC-922T9S/R)
IC1 PIN 28 (KOC-923T9S/R)
3
IC1 PIN 8 OR 9
12. PRINTED CIRCUIT BOARD
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.
Terminal
6-7
8-9
9-10
Voltage(load)
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
T : 20 ms(50Hz)
5V
0V
T
T : 250 ns(4MHz)
5V
0V
T
NO
MEASURE POINT
WAVE FORM
REMEDY
REMARK
1
MP1
DC 5V 5%
Replace ZD2, EC1
NO LOAD
2
MP2
DC 24V 20%
Replace D17-D20, EC4(KOC-922T9S/R)
NO LOAD
Replace D18-D21, EC4(KOC-923T9S/R)
