User Guide

CHAPTER 4 IMAGE FORMATION SYSTEM

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

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