Developing Bias Control Circuit - Canon NP6260 Service Manual

3. Developing Bias Control Circuit

The circuit used to control the developing bias is provided with the following func-
tions:
a. Turning on and off the AC bias
b. Controlling the voltage level of the DC bias
AC Bias OFF control developing bias remote signal ACBTP is '0'
AC bias switch circuit goes OFF.
Drive circuit goes OFF.
AC transformer T401 output is cut off.
The above condition deprives the developing cylinder of AC bias.
The above condition stops the AC bias to the developing cylinder.
AC bias ON control developing bias remote signal ACBTP is '1'
Drive circuit goes ON.
AC bias switch circuit goes ON.
The above condition causes the high-voltage transformer to increase the high-
voltage transformer to 1500 Vp-p and supply it to the developing assembly.
DC controller
PCB
Q156
J114 J779
-A3 -8
ACBTP
J114 J779
(master)
-A10 -1
Micro-
processor
HVRMT
J114 J779
-A1 -10
ROED
D/A
J114 J779
converter
-A2 -9
DCBC
COPYRIGHT © 1997 CANON INC.
High-voltage transformer (HVT)
AC transformer T401
Switch Drive
circuit circuit
Switch
circuit
Figure 4-208
CANON NP6560/NP6360/NP6260 REV. 0 NOV. 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 4 IMAGE FORMATION SYSTEM
Voltage detection
AC wave
generation
DC transformer
T402
Drive
circuit
Developing
Drum
cylinder
Roller
electrode
4-35