Troubleshooting for Horizontal White Streaks in Small Solid Black Areas

Symptom

Horizontal white streaks may appear in small solid black areas (smaller than 3cm x 3cm). (See the example below in the red circle)

Cause

Electrical charge of the Bk toner is lower compared to other toners because the Bk station is the most downstream, and the transfer bias is set higher in FC mode.

This prevents black toner from maintaining the optimum charge level, which may result in poor toner transfer.

Action

1. Print black in FC mode.
   PS driver and PCL driver
   
   • Select “Print Quality” from Detailed Settings.
   • Select “User Setting” as Settings for Images.
   • Select “CMY+K” or “Black by K (Black) – Text Only” for PS driver, and “CMY+K” for PCL driver as Gray Reproduction.
   Fiery driver
   
   • Select “Job Properties” of the affected image.
   • Select “Expert setting” from “Color” tab.
   • Select “Gray/Black Processing” Tab.
   • Specify “Normal” for Black text and graphics in order to print in CMYK mode.
2. Increase the image transfer current. (+5 to 10A from the default)
   

   [#016: Image transfer current: FC: K].
   First increase the value by +5A. Check the results and increase or decrease the value by 1A as necessary.

   Do not increase by more than +10A from the default.

   

   Risks:

   Image density may decrease in Bk solid images that have a high coverage ratio. (Density at the sides become low.)

   Ghosting of Bk halftone images

3. Adjust the paper transfer current. (-5A to -15A from the default)
   

   To ease the symptom, decrease the paper transfer current in [#026 & #027: Paper transfer current: FC: Side 1, 2].

   Decrease -5A at a time as you check the results.

   Do not decrease by more than -15A from the default.

   

   Risks:

   Low image density

   Toner scattering around solid images

4. Increase the maximum image density.
   To ease the symptom, increase the maximum image density of Bk in [#011: Maximum Image Density:K] by adjusting the notch to the [+].

   

   Side effect:

   Low toner yield

MP C6503/C8003, Pro C5200S/C5210S

Pro C5200S/C5210S only