CHAPTER 4 IMAGE TROUBLESHOOTING
4-8
6.
Fogging (overall)
7.
Fogging in paper feed direction
8.
Dark lines (broad lines in paper feed direction)
Cause/Problem
area
Dirt on the
scanner
Pre-exposure
lamps
DC controller
PCB
High-voltage
transfomer
DC controller
PCB
Action
End.
End.
1.Replace the pre-expo-
sure lamp unit.
2.Replace the DC con-
troller PCB.
Replace the DC control-
ler PCB.
1.Replace the high-volt-
age trans former.
2.Replace the drum unit.
Replace the DC control-
ler PCB.
Result
Yes
Yes
No
No
Yes
No
Check
Does the image quality improve after the
basic adjustment procedure is followed?
Does the image improve after the scanning
lamp, reflectors, mirrors, lens and dust-
proofing glass are cleaned?
Does the pre-exposure lamp go ON during
copying?
Set the meter to the 30VDC range and
measure the voltage between J307-6 (+)
and J307-7 (-) of the DC controller PCB.
Is the voltage 10V or less during copying
and approx. 16V at other times?
Is the voltage between J307-5 (+) and
J307-7 (-) of the DC controller PCB
approx. 0.6V during copying and approx.
14V at other times?
Procedure
1
2
3
4
5
Cause/Problem
area
Primary co-
rona assembly
Scanner
Pre-exposure
lamps
Feed roller
Action
End.
End.
End.
Clean the feed roller be-
low the developing unit.
Result
Yes
Yes
Yes
No
Check
Does the image quality improve after the
primary corona wires, grid wires, and co-
rona frame are cleaned?
Does the image quality improve when the
scanning lamp, reflectors, lens, mirrors,
and dust-proofing glass are cleaned?
Is the pre-exposure lamp brighter after it is
cleaned?
Procedure
1
2
3