Overview/Configuration; Overview; Parts Replacement Procedure; Laser/Scanner Unit - Canon L90 Series Service Manual

3.1 Overview/Configuration

3.1.1 Overview

[1]
[2]
[7]
[6]
The machine's laser scanner assembly consists of the laser driver and the
scanner motor, which are driven by signals coming from the DCNT board.
The laser driver serves to turn on the laser diode according to the laser con-
trol signal and video signals from the DCNT board.
The laser beam moves thorough the collimator less and the cylindrical lens
to reach the 4-facet mirror rotating at a specific speed.
The leaser beam reflected by the 4-facet mirror moves through the imaging
lens arranged in front of the 4-facet mirror to reach and focus on the photo-
sensitive drum.
When the 4-facet mirror rotates at a specific speed, the laser beam scans the
photosensitive drum in keeping with the mirror rotation, thus drawing static
images on the photosensitive drum.
Memo:
BD Fault
The machine identifies a BD fault if it does not detect the /BDI signal
within 0.1 sec after the scanner motor is forced to accelerate. It also
detects a BD fault if it does not detect a specific interval of /BDI
signals for 2 sec continuously after the scanner motor has reached a
specific revolution (number of rotations).
Scanner Fault
If the machine does not detect the /BDI signal 1.5 sec after it has
stopped forcing the scanner motor to accelerate, it extends the period
of detection by 120 sec; if it still does not detect a specific interval of
/BDI signals, it identifies a scanner fault.
BD Error
The machine identifies a BD error if it does not detect the /BDI signal
at a specific interval while the /BDI signal is being generated. It,
however, does not identify a BD error under the following condition:
-the door is identified as being open within 0.2 sec after detection of a
BD error.
The laser/scanner unit contains parts that cannot be adjusted in the
field. Do not attempt to disassemble the laser/scanner unit.
[4]
[5]
F-3-1
[1] Laser driver PCB
[2] BD sensor
[3] Photosensitive drum
[4] Imaging lends
0018-4899
[3]
[5] Scanner motor
[6] 4-facet mirror
[7] Cylindrical lens

3.2 Parts Replacement Procedure

3.2.1 Laser/Scanner Unit

3.2.1.1 Preparation for Removing the Laser/Scanner Unit

1) Remove the document feed tray and the paper tray cover. (page 7-2)Ref-
erence[Removing the Document Feed Tray and the Paper Tray Cover]
2) Detach the right cover. (page 7-2)Reference[Detaching the Right Cov-
er]
3) Detach the left cover. (page 7-2)Reference[Detaching the Left Cover]
4) Detach the front cover. (page 7-1)Reference[Detaching the Front Cov-
er]
5) Detach the rear cover. (page 7-1)Reference[Detaching the Rear Cover]
6) Detach the cartridge cover. (page 7-3)Reference[Detaching the Car-
tridge Cover]
7) Remove the control panel unit. (page 7-4)Rference[Removing the Con-
trol Panel Unit]
8) Detach the upper cover. (page 7-3)Reference[Detaching the Upper Cov-
er]
9) Remove the reader unit. (page 2-5)Reference[Removing the Reader
Unit]
10) Remove the DCNT board. (page 7-4)Reference[Removing the DCNT
Board]

3.2.1.2 Removing the Laser/Scanner Unit

1) Remove the 4 screws [1], and detach the Laser/Scanner unit [2].
T-3-1
[1] [2]
F-3-2
Chapter 3
0018-4182
0018-4183
[1]
3-1