B. Controlling The Primary Charging Roller Bias - Canon GP215 Service Manual

3. OPERATIONS AND TIMING

B. Controlling the Primary Charging Roller Bias

1. Outline
The bias for the primary charging roller is controlled by the composite power supply PCB according to
the instructions from the DC controller PCB.
In addition, an AC bias is applied to the primary charging roller to ensure stable charging.
The composite power supply PCB serves the following functions:
• Controlling the DC bias to a specific voltage
• Controlling the AC bias to a specific current
Composite power supply PCB
T101
T101
Drive
circuit
Q605
J209-B6
J209-B2
J102-B9
J102-B5
IC101
DC controller PCB
3–60
COPYRIGHT © 1996 CANON INC.
Rectification
AC drive
circuit
DC
current Frequency
division
setection
CPU
J209-A4~A9
J102-A1~A7
CPU
Figure 3-503
CANON GP215/200 REV.0 JULY 1996 PRINTED IN JAPAN (IMPRIME AU JAPON)
Primary charging
assembly
T300
Photo-
sensitive
drum
AC component
current detection
Drum ambient
temperature detection