Making Checks On The Printer Side (1/2) - Canon iR8500 Service Manual

CHAPTER 6 TROUBLESHOOTING

1.1.2 Making Checks on the Printer Side (1/2)

<Checking the Images>
Using PG4, PG7, and PG8
Is there a
NO
horizontal line in
the image?
YES
Clean the following, and check
them for adhesion of foreign
matter:
[1] Dust-proofing glass
[2] Charging assemblies
[3] Developing cylinder
Is there a
NO
horizontal line in
the image?
YES
6-4
<Checking the Density Slope>
Check the image using PG4.
Is there a
NO
difference in density
between front
and rear?
YES
Is the rear
NO
lighter?
YES
Turn the adjusting
Turn the adjusting
screw at the front of
screw at the rear of
the primary charging
the primary charging
assembly counter-
assembly counter-
clockwise (2 turns
clockwise (2 max.).
max.).
Execute potential
control.
Turn off and then on the power
switch, and generate a single test
print using PG7 or PG4.
Caution:
1. If there still is a difference in density after giving the adjusting
screw 2 turns on one side (each turn causing a change of
about 0.7 mm), check the charging assembly, scanning lamp,
and scanner for dirt.
2. When turning the adjusting screw counterclockwise, take care
so that the distance between the wire and the grid is not less
than 7.5 mm.
Reference:
Moving the wire away from the wire makes the image darker,
while bringing it closer makes the image lighter.
F06-101-02
<Checking the Solid Black Density>
Check PG8 (solid black).
Is the output
YES
free of a fuzzy image
and the density
appropriate?
NO
Make the following selections in
service mode:
COPIER>DISPLAY>DPOT>VDM.
Check the primary charging
NO
Is the reading of
system and the potential control
'VDM' between 360
system; if normal, replace the
and 420?
photosensitive drum.
YES
Make the following selections in
service mode:
COPIER>DISPLAY>DPOT>VL1M.
Check the following; if faulty,
replace it:
Is the reading NO
1. Laser output
of 'VL1M' between
2. Potential control system
50 and 90?
YES
Check the following of the
developing assembly system:
YES
Is the test print PG6
1. Developing bias
(solid white) foggy?
2. Sleeve for toner coating
NO
Perform the following:
1. Vary the settings of the following with reference to
the following table: ADJUST>V-CONT>VD-OFST and
ADJUST>V-CONT>VL-OFST:
Darker images
Lighter images
Default
VD-OFST -4 -3 -2 0 +2 +3
VL-OFST +4 +3 +2 0 -2 -3
COPYRIGHT© 2001 CANON INC. 2000 2000 2000 2000
A
+4
-4
CANON iR8500/7200 REV.1 AUG. 2001