Controlling The Pre-Exposure Lamp - Canon NP6412 Service Manual

CHAPTER 4 IMAGE FORMATION SYSTEM
G.

Controlling the Pre-Exposure Lamp

1. Outline
The machine is equipped with a pre-exposure lamp to ensure stable generation of images by
removing residual charge from the photosensitive drum.
2. Operations
a. Controlling the Intensity of the Pre-Exposure Lamp
The intensity of the pre-exposure lamp is controlled based on the settings of '33' (IP_OFST)
and '37' (PREX_LP) made in service mode.
The microprocessor (Q101) on the DC controller PCB controls the pre-exposure lamp control
signal (PEXP*) according to the levels of IP_OFST and PREX_LP so as to vary the voltage sup-
plied to the pre-exposure lamp.
Related Service Mode
33 (IP_OFST)
37 (PREX_LP)
+5V
CPU
(Q101)
Q184
DC controller PCB
Reference:
The levels of PREX_LP and IP_OFST are adjusted and stored at the factory. If you have
replaced the pre-exposure lamp or the drum unit, be sure to enter the values recorded on the
label attached to each part.
4-24
COPYRIGHT © 1999 CANON INC.
Corrects the current used during APVC measurement.
Adjusts the intensity of the pre-exposure lamp.
+24VU
J121 J801
-2
-1
PEXP*
(PWM signal)
Figure 4-120
CANON NP6512/6612/7120/7130/7130F REV.0 AUG. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
-1
-2
Pre-exposure lamp(LA2)