Oki OKIOFFICE44 Service Manual page 283

3) High-voltage and medium-voltage control
High voltages are activated by IOGA and generated by the high-voltage circuit inside the
power supply unit. The CH (charge) voltage of about -1.35kV is used for the charge roller.
The TR1/TR2 (transfer) voltage of about +3.5kV/-0.75kV is used for the transfer roller.
Medium voltages are activated by IOGA and generated by the medium-voltage circuit
inside the power supply unit. The SB1/SB2 (toner supply) voltage of about +0V/-450V is
used for the toner supply roller. The DB1/DB2 (developing) voltage of about +300V/-
300V 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.
R44
IOGA
DBON1
DBON2
DBPWM
TR1PWM
CHPWM
TR2PWM
Board Descriptions
Signal Name
CHON "1": CH is output.
DBON1 "1": + ive polarity voltage of DB/SB is output.
DBON2 "1": - ive polarity voltage of DB/SB is output.
TRON1 "1": + ive polarity voltage of TR is output.
TRON2 "1": - ive polarity voltage of TR is output.
TLHV (OLHV)
CH
High-voltage
TR1/TR2
generation
circuit
Medium-
voltage
CB
generation
circuit
DB1/DB2
SB1/SB2
Figure A3.2.17 High/Medium Voltages Control
A - 41
Description
Contact assy.
Charge roller
EP drum
Cleaning roller
Transfer roller
OKIOFFICE 44 Serv. Man., P/N 59276801
Developing roller
Toner supply roller