Oki OKIFAX4550 Maintenance Manual page 347

3) High-voltage and medium-voltage control
High voltages are activated by IC2(IOGA6) and generated by the high-voltage circuit inside
the power supply unit. The CH (charge) voltage of about -1.30kV is used for the charge
roller. The TR1/TR2 (transfer) voltage of about +3.9kV/-0.75kV is used for the transfer
roller.
Medium voltages are activated by IC2(IOGA6) 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 +265V/
-265V is used for the developing roller. The CB (cleaning) voltage of about +400V/-1.35kV
is used for the cleaning roller.
Figure A.28 (4/4) shows high/medium voltages control.
* Signals used to control the high/medium-voltages are listed below.
Signal Name
DBON1
DBON2
TRON1
TRON2
CB1ON
CB2ON
R46
IC2
IOGA6
DBON1
DBON2
DBPWM
TR1PWM
CHPWM
TR2PWM
41309401TH Rev.4
CHON "1": CH is output.
"1": + ive polarity voltage of DB/SB is output. (+265V)
"1": - ive polarity voltage of DB/SB is output. (-265V)
"1": + ive polarity voltage of TR is output.
"1": - ive polarity voltage of TR is output.
"1": + ive polarity voltage of CB is output.
"1": - ive polarity voltage of CB is output.
P2H
CH
High-voltage
TR1/TR2
generation
circuit
Medium-
voltage
CB
generation
circuit
DB1/DB2
SB1/SB2
Figure A.28 (4/4) High/Medium Voltage Control
Description
(-1.30kV)
(+3.9kV)
(-0.75kV)
(-1.35kV)
Contact assy.
Charge roller
EP drum
Cleaning roller
Transfer roller
(+400V)
Developing roller
Toner supply roller
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