Canon NP6512 - Controlling the Pre-Exposure Lamp

CHAPTER 4 IMAGE FORMATION SYSTEM
COPYRIGHT © 1999 CANON INC. CANON NP6512/6612/7120/7130/7130F REV.0 AUG. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON) 4-24
Figure 4-120
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) Corrects the current used during APVC measurement.
37 (PREX_LP) Adjusts the intensity of the pre-exposure lamp.
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.
Pre-exposure lamp(LA2)
DC controller PCB
CPU
(Q101)
+5V
Q184
J121
-2
-1 -2
+24VU
PEXP*
(PWM signal)
J801
-1