Oki OKIFAX 5400 Maintenance Manual page 216

ACTION Item:
No.
9 Probable cause 1: D85 is defective.
Check item 1:
Probable cause 2: The load is larger than the normal value.
Check item 2:
Probable cause 3: D52 is defective.
Check item 3:
10 Probable cause 1: Q11 and Q12 are malfunctioning.
Check item 1:
Check item 2:
11 Probable cause 1: Current set resistor R115 is defective.
Check item 1:
Probable cause 2: The reference voltage is incorrect.
Check item 2:
Check item 3:
12 Probable cause 1: CC (Constant Current) mode is not set.
Check item 1:
Probable cause 2: T2 is defective.
Check item 2:
Probable cause 3: Check (3) of ACTION 11.
13 Probable cause 1: The voltage memory circuit is malfunctioning.
Check item 1:
14 Probable cause 1: D65 or D66 is defective.
Check item 1:
Check item 2:
Check item 3:
15 Probable cause 1: The class of D76 or D82 is incorrect.
Check item 1:
Probable cause 2: The load current is lower than the specified value.
Check item 2:
40838301TH Rev.1
Replace D85.
Check if the load current is 2µA or less.
Check if D52 is iZ300 class Y or Z (class X is not acceptable).
Check the PWM waveform of DB output (cycle: 142 µs, ON time: 36µs).
Check Q11 and Q12. Check the base voltage of Q21, Q22 and Q23 (3.7V
or more to 3.9V or more).
Check R115 (tolerance error: +/-1%)
Check if the voltage at CN3-B10 pin is 2.5V.
Check the PWM waveform of TR1 (cycle: 142Ms, ON time: 36 µs).
Check if TR SEL2 is "H".
Replace T2. Check T2.
Check if the average value of the VSEN voltage in the CC mode is equal
to that in the CV (Current Voltage) mode.
Check if the voltage across C230 remains unchanged in the CV mode (for
15 seconds or more).
Check if these diodes are 1ZB390.
Check the PWM waveform of TR2 output (cycle: 146µs, ON time: 36µs).
Check if TR1 is "L" or TR2 is "H" (if TR1 is "H", TR1 output appears).
Check if both D76 and D82 are of EB-2 class.
The load current shall be 6 to 8µA. (Namely, the load current shall not be
more than or less than this limit range.)
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ACTION