PRINTED CIRCUIT BOARD
1. CIRCUIT CHECK PROCEDURE
1. Low voltage transformer check
The low voltage transform er is located on the P.C.B.
M easuring condition: Input voltage: 230 V / Frequency: 50Hz
2. Voltage Check
- Key check point
- Check m ethod
Term inal Voltage
LO AD
N O LO A D
4 - 7
A C 12.6 V
A C 14.7 V
NO
CHECK POINT
REMARK
1
IC1 P IN 2,21,30,34
-5VD C
2
IC 1 P IN 35
T : 20m s(50H z)
3
IC1 P IN 31 O R 32
T : 250 ns(4M H z)
NO
MEASURE POINT
W AVE FORM
REMEDY
REM ARK
1
M P 1
D C -5V ± 0.25V
R eplace V L1, E C 1
N O LO A D
2
M P 2
D C -12V ± 2.0V
R eplace E C 2, D12,13,14
N O LO A D
NOTE
1. Refer to Circuit 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 nom inal voltage.
NOTE
Each m easure point m ust be m easured with G ND points.
