Oki OKIOFFICE84 Maintenance Manual page 296

P2H
1. High-voltage section
1.1 Functional overview
The high-voltage outputs consist of TR1 (3.9 kV), TR2 (-0.75 kV), DB1 (+265 V), DB2 (-
265 V), SB2 (-550V), CB1 (+400 V), CB2 (-1.35 kV) and CH (-1.30 kV) and are obtained
as follows. The control signal obtained from IOGA4 of R51 board is applied to High-
voltage power supply circuit. As result, the driver current is applied to the drive circuit,
which will provide the high-voltage outputs.
Note:
1.2 SB2, DB1, DB2 (P2H)
1)
2)
3)
1.3 TR1 and TR2 (P2H)
1)
2)
3)
4)
1.4 CH
1)
1.5 CBI, CB2
1)
40672201TH Rev. 4
Signal Name
Output Voltage
SB1/SB2
0±5 V/-550 V
DB1/DB2
+265 V/-265 V
TR1/TR2
+3.9 kV/-0.75 kV
CH
-1.30 kV
CB1 +400 V
CB2
-1.35 kV
These four high-voltage outputs are obtained from the flyback voltage of Q10.
The positive and negative voltages of DB1 and DB2 are obtained by switching the
charging direction under the triac and thyristor.
Feedback is not applied to these outputs. However, SB2 is limited by D85 and
DB2 is limited by D84 so as not to provide an output exceeding a preset voltage.
The TR1 high-voltage is obtained by rectifying the secondary output of Q17
switching circuit by a voltage-doubler rectifier.
TR1 output circuit has both constant current (hereinafter called CC) and constant
voltage (hereinafter called CV) modes.
At first, TR1 output circuit operates in the CC mode. Once the voltage determined
by parameters such as roller and medium is obtained, this circuit changes to
operate in the CV mode by the control signal.
The TR2 output voltage is regulated by keeping the voltage obtained by switching
operation of Q15 at a constant voltage by D66 and D65.
(P2H)
The CH output voltage is stabilized by keeping the primary flyback voltage ob-
tained by switching operation of Q16 at a constant voltage by D76 and D82.
(P6L)
The CB1 output voltage is stabilized by keeping the primary flyback voltage
obtained by switching operation of Q2 at a constant voltage by D7 and D6 and D5.
Application
Voltage applied to toner supply roller.
Voltage applied to developing roller.
Voltage applied to transfer roller.
Voltage applied to charging roller.
Voltage applied to cleaning roller.
Voltage applied to cleaning roller.
A3 - 26
P2H
P2H
P2H
P2H
P6L
P6L