2NC/2NF/2NG/2NN/3P7/3P8/3P9
1-4-79
(10) Black dots appear on the image.
Print example Cause of trouble
1. Dirty charging roller
2. Flawed or dirty drum unit
3. Damaged or paper dust bitten cleaning blade
Defective part Check description Corrective Action
1
Drum unit Check the print image on paper
has a problem at an interval
equivalent to the circumference
of the drum (126mm).
If the drum has scratches, replace the drum
unit. (see page 1-5-40)
2
Charging roller Check the print image on paper
has a problem at an interval
equivalent to the circumference
of the charging roller (38mm).
A problem is observed at a constant interval of
the charging roller (38 mm), replace the
charging roller. (see page 1-5-40)
3
Developer unit 1. Check if that the developing
bias is leaked.
Execute AC calibration by U140.
(see page 1-3-51)
2. Check the print image on
paper has a problem at an
interval equivalent to the
circumference of the
developing roller (39mm).
1. If the print image on paper has a problem
at an interval equivalent to the
circumference of the developer roller, clean
the developer unit.
2. Replace the developer unit.
(see page 1-5-35)
4
Transfer roller unit. Check if the transfer roller is con-
taminated on its surface or dam-
aged.
Replace the transfer roller unit.
Check the cleaning bias connec-
tor or the connecting terminals of
high voltage are not dirty or
deformed.
1. If the connector or terminals are dirty,
clean.If the connecting terminals are
deformed, correct for a proper conduction.
2. Replace the high-voltage circuit PWB.
5
Fuser unit Check the print image on paper
has a problem at an interval
equivalent to the circumference
of the fuser roller.
1. If the print image has a problem, clean the
fuser roller.
2. If cleaning does not help improve the
symptom, replace the fuser unit.
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