Grid Bias Corrective Control; Determining The Optimum Grid Bias - Canon ImageRunner iR8500 Series Service Manual

Main power
switch ON
[1] The control panel power switch is turned on.
[2] The front door is opened/closed.

8.3.4 Determining the Optimum Grid Bias

iR105i/iR105+ / iR9070 / iR85+ / iR8070
A grid bias is selected so that the surface potential of the drum will be identical to the target potential (the primary charging bias is fixed).
Potential sensor
Primary charging
bias (DC)
Grid bias

8.3.5 Grid Bias Corrective Control

iR105i/iR105+ / iR9070 / iR85+ / iR8070
Potential control is executed 10 min and 60
min after the temperature of the fixing
assembly has reached 195˚C.
Potential
Potential control for
control transparency
Fixing assembly temperature at 195˚C
(end of fixing assembly warm-up)
Related Service Mode
COPIER> OPTION> BODY> PO-CNT
(potential control on/off)
COPIER> ADJUST> V-CONT> EPOTOFST
(potential sensor offset value input)
COPIER> ADJUST> V-CONT> VL-OFST
(VL target potential offset input)
COPIER> ADJUST> V-CONT> VD-OFST
(VD target potential offset value input)
COPIER> FUNCTION> DPC> OFST
(potential sensor offset adjustment)
The relationship between the surface potential of
the drum (VD) and the gird bias is obtained based
on measurements taken several times.
VD3
VD2
VD1
500V 600V 700V
Grid bias
195˚C
WMUP
Measurement
(VD1)
500 V
Potential control
sequence started
The charging characteristics are likely to have
stabilized at this point, and potential control will
not be executed after this point.
10 min
Print com- Potential
mand control
Print com-
mand
F-8-10
T-8-4
0: disable potential control.
1: enable potential control. (default)
If you have replaced the image processor
PCB or initialized the RAM on the image
processor PCB, enter the value recorded on
the service label.
For adjustments, see descriptions on
electrical parts.
Charging
characteristic curve
If the target VD is attained basde on this
measurement, control is ended; otherwise,
corrective control will start.
WMUPR
Measurement
Measurement
Measurement
(VD2)
(targetVD)
(VD3)
Vg
600 V 700 V
A grid bias (VG) needed to attain the
target VD is selected.
F-8-11
60 min
Potential
control
200˚C
STBY
Chapter 8
0006-9596
0006-9598
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