Oki OKIFAX 5400 Maintenance Manual page 300

3) High-voltage and medium-voltage control
High voltages are activated by CPU and generated by the high-voltage circuit inside
the power supply unit. The CH (charge) voltage of about -1.35 kV is used for the charge
roller. The TR1/TR2 (transfer) voltage of about +3.5 kV/-0.75 kV is used for the transfer
roller.
Medium voltages are activated by CPU and generated by the medium-voltage circuit
inside the power supply unit. The SB1/SB2 (toner supply) voltage of about +0 V/-450
V is used for the toner supply roller. The DB1/DB2 (developping) voltage of about +300
V/-300 V is used for the developing roller. The CB (cleaning) voltage of about +400V
is used for the cleaning roller.
Figure A3.1.17 shows high/medium voltages control.
* Signals used to control the high/medium-voltages are listed below.
E17
CPU
DBON1
DBON2 25
29
DBPWM
30
TR1PWM
31
CHPWM
33
TR2PWM
35
40838301TH Rev.1
Signal Name
CHPWM P.W.M : CH is output.
DB1ENB "1": + ive polarity voltage of DB1/SB1 is output.
DB2ENB "1": - ive polarity voltage of DB2/SB2/CB is output.
TR1PWM P.W.M : TR1 is output.
TR2PWM P.W.M : TR2 is output.
DBPWM P.W.M : DB/SB/CB is output.
1VP/2VP (Power supply unit)
CH
High-voltage
TR1/TR2
generation
circuit
Medium-
voltage
CB
generation
circuit
DB1/DB2
SB1/SB2
Figure A3.1.17 High/Medium Voltage Control
Description
Contact assy.
Charge roller
Cleaning roller
Transfer roller
A3 - 19
Developing roller
EP drum
Toner supply roller
E17