Color Shift - Ricoh B202 Service Manual

TROUBLESHOOTING GUIDE 2

4.6.2 COLOR SHIFT

The following briefly explain the factors causing color shifts and what to do on the machine to correct it:
• Temperature change causes the optical components in the laser
optics housing unit to contract, causing the main scan
magnification to change. To correct the line position, the machine
automatically does the line position adjustment when the
temperature changes by 5°C since the last position adjustment.
If the line position adjustment functions correctly, no color shift
occurs. If the line position adjustment fails (result: SP5-993-007),
color lines may shift anywhere on the outputs.
• The process speed at each stage (registration roller, transfer belt,
and fusing belt/roller) affects the paper transport speed. If the
paper transport speed changes during image transfer of a color,
the color line being transferred shifts with respect to the color line
already transferred to the paper. The registration roller speed
(adjusted by color development motor speed) and fusing belt/roller
speed (adjusted by black development motor speed) are adjusted
by the manufacturer.
Paper speed may slightly change due to the type of paper used or
after replacing the parts related to the drive sections of the
registration section, transport unit, and fusing unit. (After replacing
the fusing unit, the speed adjustment should be done in the User
Program mode.) Also, the position where color shift occurs
depends on which section starts moving at the incorrect speed.
• Paper skew directly affects the color shift between the front and
rear sides. There are several factors. One of them is the position of
the side fences.
B202/B178/B180
The black development motor drives the
fusing unit pressure roller. The motor
speed is adjustable in the SP mode.
The transfer motor drives the
transfer belt. The motor speed
is not adjustable.
The color development motor drives
the registration rollers. The motor
speed is adjustable in SP mode.
4-64
K
Y
C
M
B178T905.WMF
SM