Oki OF5600, Service Manual

Page: 336 / 448

Board Descriptions A - 52 OF 5300/5600 Serv Man, P/N 59278301
5-6 High-voltage Section
5-6-1 Functional overview
The high-voltage outputs consist of TR1 (3.5 kV), TR2 (-0.75 kV), DB1 (+300 V), DB2 (-300 V),
SB2 (-450V), CB (+400 V) and CH (-1.35 kV) and are obtained as follows. The control signal
obtained from IOGA of M17 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:
Signal Name
SB1/SB2
Output Voltage
0
±
5 V/-450 V
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.
+300 V/-300 V
+3.5 kV/-0.75 kV
-1.35 kV
+400 V
Application
DB1/DB2
TR1/TR2
CH
CB
5-6-2 SB2, DB1, DB2 and CB
1) These four high-voltage outputs are obtained from the flyback voltage of Q10.
2) The positive and negative voltages of DB1 and DB2 are obtained by switching the
charging direction under the triac and thyristor.
3) 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.
5-6-3 TR1 and TR2
1) The TR1 high-voltage is obtained by rectifying the secondary output of Q17
switching circuit by a voltage-doubler rectifier.
2) TR1 output circuit has both constant current (hereinafter called CC) and constant
voltage (hereinafter called CV) modes.
3) 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.
4) The TR2 output voltage is regulated by keeping the voltage obtained by switching
operation of Q15 at a constant voltage by D66 and D65.
5-6-4 CH
1) 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.