Oki OKIOFFICE 84 Service Manual page 403

The ACON control signal on the secondary side is transmitted to the primary side via PC4 to turn triac TRA1 for AC
voltage supply to the heater.
3) High-voltage and medium-voltage control
High voltages are activated by IOGA4 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 IOGA4 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 A3.1.15 shows high/medium voltages control.
* Signals used to control the high/medium-voltages are listed below.
Signal Name
CHON
DBON1
DBON2
TRON1
TRON2
CB1ON
CB2ON
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Description
"1": CH is output. (-1.30kV)
"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. (+3.9kV)
"1": - ive polarity voltage of TR is output. (-3.9kV)
"1": - ive polarity voltage of CB is output. (+400V)
"1": - ive polarity voltage of CB is output. (-1.35kv)