Canon NP6412 Service Manual page 107

4. Developing DC Bias Voltage Level Control
The DC bias control signal (BIAS_PWM) is varied according to the following settings so as to
vary the DC component of the developing bias, thereby controlling the copy density:
• Density lever setting (for manual density adjustment)
• AE sensor output (auto density adjustment)
• Copy mode settings (toner save mode/photo mode)
• Density correction dial (VR107) setting
You can use the density correction dial (VR107) on the DC controller PCB to vary the develop-
ing DC bias. Change the bias if copies tend to be foggy or light images because of shifts in the
sensitivity of the photosensitive drum. The dial is used when manual density adjustment or auto
density adjustment (AE) is executed.
COPYRIGHT © 1999 CANON INC.
Figure 4-108
CANON NP6512/6612/7120/7130/7130F REV.0 AUG. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 4 IMAGE FORMATION SYSTEM
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