Symptom

Vertical bands of uneven image density appear in halftone images on the rear side of duplex copies/prints when printing onto coated paper in low-temperature, low-humidity environments (10°C, 15%).

1: Approximately 30mm

2: Approximately 50mm

[A]: Bands of low density (at approx. 30-50mm from the center)

[B]: Density is relatively high at the ends of bands

Cause

Friction between the paper and the registration roller generates an electrical charge on some areas of the paper, after the paper has passed through the fusing unit to fuse the first side. The areas on the paper are charged differently, and these differences are visible as bands.

Solution

Lower the paper transfer bias for the second side.

Pro C5200S/C5210S:

  • The user can use the IMSS settings to lower the bias.
  • If the symptom occurs in full-color mode, use [027. Paper Transfer Current: FC: Side 2] in IMSS setting.
  • If the symptom occurs in B/W mode, use [021. Paper Transfer Current: BW: Side 2] in IMSS setting.

  • When using plain paper, the setting can be changed using 2-652-001 to 009 (for each paper thickness and type) and 2-642-001 to 009 (for each paper thickness and type).

MP C6503/C8003:

A customer engineer must perform the following adjustment:

  • If the symptom occurs in full-color mode, lower the value of SP2-652-001 to 009 (for each paper thickness).
  • If the symptom occurs in B/W mode, lower the value of SP2-642-001 to 009 (for each paper thickness).
  • The value must be between [default value] and [default value - 20A].

  • The density of solid images may be decreased if the bias is too low (especially for high-density solid image areas). In addition, other image problems may occur.