Black Dots; Horizontal Streaks; Black Vertical Streaks - Mita DP-2800 Service Manual

Black dots

Note the spacing of the
defects. Use the Repetitive
defects gauge on page 6-39.

Horizontal streaks

Check drum ground.
Check main charger contacts.
The drum unit may be
defective.

Black vertical streaks

ABC
123
Contaminated main charger
wire.
Check the drum surface for
a streak of toner laying
lengthwise.
Defective developer unit.
• If the defects occur at regular intervals of 94 mm, the
problem may be a damaged drum unit or fuser roller.
Replace the drum unit or fuser unit accordingly.
• If the defects occur at random intervals, the toner may
be leaking from the drum unit. Replace the drum unit.
• If the defects occur at regular intervals of 38 mm, the
problem may be a toner lump on the developing roller.
Remove the lump using a soft brush. Note that the
developing roller surface is fragile: Contact the
manufacturer for type of the brush to use.
• The drum axle and its counter part—drum grounding
tab in the printer must be in a good contact. If necessary,
apply a small amount of electro-conductive grease
onto the tab. See the manufacturer for which type of
grease to use.
• Take out the main charger unit; check the electric
terminals to see if they are clean.
• Replace the drum unit.
• Clean the main charger wire by pulling the green
colored cleaning knob in and out several times.
• A streak of toner remaining on drum after printing
means that the cleaning blade in the drum unit is not
working properly. Replace the cleaning blade; or replace
the drum unit.
• Replace the developer unit.
5A2
6-35