Oki B4100 User Manual
Page 312
40055101TH Rev.4
312 /
ACTION Item:
No.
ACTION
1
Probable cause 1:
A double AC voltage is applied (200V is applied to a 120V transformer).
Check item 1:
Check the input AC voltage.
Probable cause 2:
A short-circuit between lines after F2.
Check item 2:
Check the pattern on PCB and T1.
2
Probable cause 2:
Short-circuit in 30V output circuit.
Check item 1:
Check DS1, C7, and R53.
Probable cause 2:
A short-circuit in 5V output circuit.
Check item 2:
Check Q1, D6, D7, C6, C10, C20, D6, D8, R4, R9, R83, R10, R11, and C35.
If D8 and D6 operate and F3 blows when 5V overvoltage is detected, D8 and Q1
may be detective. Replace both D8 and Q1.
3
Probable cause 1:
If the AC voltage is high (127V or more)/(250V or more), the output voltage
becomes higher than the specified value. If the AC voltage is low (102V or less)/
(198V or less), the output voltage becomes lower than the specified value.
Check item 1:
Check the AC voltage.
Probable cause 2:
If the load setting is large, the output voltage becomes lower than the specified
value.
Check item 2:
Check the load resister.
Probable cause 3:
DS1 is defective (if the 30V output voltage is low).
Check item 3:
Check DS1 and R53.
4
Probable cause 1:
F3 blows.
→
See ACTION 2.
Probable cause 2:
T1 is defective.
Check item 2:
Check secondary side pins 1 to 3 and primary side pins 1 and 2 of T1.
Check item 3:
Check DS1 for shorting and opening.
5
Probable cause 1:
D10 and D11 are defective.
Check item 1:
Check the AC voltage.
Probable cause 2:
T1 is defective.
Check item 2:
Check pins 5 and 6 of T1 (thermal fuse may blow).
6
Probable cause 1:
The reference resister is defective.
Check item 1:
Check R83, R10 and R11 (tolerance error: +/- 1%).
Probable cause 2:
IC1 is defective.
Check item 2:
Check IC1-1 pin (normal value: 2.45 to 2.69V).
7
Probable cause 1:
F3 blows.
→
See ACTION 2.
8
Probable cause 1:
C19 and C20 are defective.
Check item 1:
Check C10 and C20.
Probable cause 2:
L3 is defective.
Check item 2:
Check L3.
Probable cause 3:
C8 and C35 are defective.
Check item 3:
Check C8 and C35.