Oki B 4100 Maintenance Manual page 312

ACTION Item:
No.
1 Probable cause 1:
Check item 1:
Probable cause 2:
Check item 2:
2 Probable cause 2:
Check item 1:
Probable cause 2:
Check item 2:
3 Probable cause 1:
Check item 1:
Probable cause 2:
Check item 2:
Probable cause 3:
Check item 3:
4 Probable cause 1:
Probable cause 2:
Check item 2:
Check item 3:
5 Probable cause 1:
Check item 1:
Probable cause 2:
Check item 2:
6 Probable cause 1:
Check item 1:
Probable cause 2:
Check item 2:
7 Probable cause 1:
8 Probable cause 1:
Check item 1:
Probable cause 2:
Check item 2:
Probable cause 3:
Check item 3:
40055101TH Rev.4
A double AC voltage is applied (200V is applied to a 120V transformer).
Check the input AC voltage.
A short-circuit between lines after F2.
Check the pattern on PCB and T1.
Short-circuit in 30V output circuit.
Check DS1, C7, and R53.
A short-circuit in 5V output circuit.
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.
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 the AC voltage.
If the load setting is large, the output voltage becomes lower than the specified
value.
Check the load resister.
DS1 is defective (if the 30V output voltage is low).
Check DS1 and R53.
F3 blows. See ACTION 2.
T1 is defective.
Check secondary side pins 1 to 3 and primary side pins 1 and 2 of T1.
Check DS1 for shorting and opening.
D10 and D11 are defective.
Check the AC voltage.
T1 is defective.
Check pins 5 and 6 of T1 (thermal fuse may blow).
The reference resister is defective.
Check R83, R10 and R11 (tolerance error: +/- 1%).
IC1 is defective.
Check IC1-1 pin (normal value: 2.45 to 2.69V).
F3 blows. See ACTION 2.
C19 and C20 are defective.
Check C10 and C20.
L3 is defective.
Check L3.
C8 and C35 are defective.
Check C8 and C35.
ACTION
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