Image Quality Problems - Samsung CLP-775ND Series Service Manual

4.2.3. Image quality problems

1) Vertical Black Line and Band
• Description
a) Straight thin black vertical line occurs in the printed image.
b) Dark black vertical bands occurs in the printed image.
Cause and Check Point
Check if the surface of the charge roller is scratched or
contaminated.
Check if there are grooves on the circumference of the OPC
drum.
Check if the cleaning blade is damaged
Is the charge roller of PTB unit damaged?
Check if paper transfer belt is damaged or contaminated.
2) Vertical White Line
• Description : White vertical voids in the image.
Cause and Check Point
Check if the LSU window or internal lenses of LSU is
contaminated.
Check if there are scratches on the circumference of the
OPC drum.
Check if there are scratches on the circumference of the
developing roller.
Foreign objects inside the toner cartridge.
Check if there are vertical scratches on the transfer unit.
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4. Alignment and Troubleshooting
Solution
Replace the toner cartridge and test again.
Replace the toner cartridge and test again.
Replace the toner cartridge and test again.
Clean the charge roller of PTB unit, or replace the PTB unit.
Replace the PTB unit and test again.
Solution
Clean the LSU window with recommended cleaner(IPA).
Clean the window with a clean cotton swab. If dirt is inside
the LSU, replace the LSU.
Replace the toner cartridge.
Replace the toner cartridge.
Replace the toner cartridge.
Replace the PTB unit.
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