Controlling The Developing Bias - Canon NP6621 Service Manual

OPERATIONS AND TIMING
G. Controlling the Developing
Bias
1. Outline
Figure 3-308 shows the circuit that controls the
developing bias, and the circuit has the following
functions:
• Turns ON/OFF the developing bias AC
component.
• Turns ON/OFF the developing bias DC
component.
• Controls the voltage level of the developing
bias DC component.
• Controls the developing bias DC component
to a constant voltage.
Composite power supply PCB
Developing
DC bias drive
Developing
DC bias voltage
detection circuit
AE sensor
Copy Density key
3–46
T4
circuit
BPWM
BIASS
DC controller PCB
Figure 3-308
COPYRIGHT © 1998 CANON INC.
24V
Developing AC bias transformer
T301
Developing AC
transformer
drive circuit
Microprocessor
J5
J307
Q301
Microprocessor
CANON NP6621 REV.0 FEB. 1998 PRINTED IN JAPAN (IMPRIME AU JAPON)
Photosensitive
drum
Developing
cylinder
VR850
Copy density
correction volume