Scanning System - Canon LBP 2460 - B/W Laser Printer Service Manual

CHAPTER 2
C. Scanning System
Figure 2-3-4 shows the scanner motor control circuit.
CPU (IC201)
J201-C6 /PRNT
64
P10/A0
The scanner motor is a three-phase, eight-pole DC brushless motor with a HALL element. It
forms a unit with the scanner driver, which controls the scanner motor rotation at a constant
speed.
When the printer is turned ON, the oscillation frequency of the crystal oscillator (X202) is
divided by the gate array (IC205), and the SCNCLK signal is sent to the scanner driver.
The /PRNT signal sent to the CPU (IC201) on the DC controller becomes "L", the CPU sets
the /SCND signal to "L" through the extended I/O (IC203). When it goes "L", the scanner driver
rotates the scanner motor using the SCNCLK signal. When the scanner motor reaches its
prescribed speed, it sets the SCANNER MOTOR READY signal (/SCNRDY) signal to "L".
The CPU on the DC controller PCB monitors the /SCNRDY signal through the gate array to
make sure that the scanner motor runs at the correct speed.
The CPU notifies to the video controller of a scanner failure in the following cases:
a. When the /SCNRDY signal does not become "L" within 30 seconds from the scanner motor
starting rotation.
b. When the /SCNRDY signal goes "H" for 1.5 seconds from going "L."
2 - 30
DC controller PCB
Gate array (IC205)
40
Gate array X1I
interface bus
28
SCNCK
29
NSRDY
Extended I/O
interface bus
30
C16
Extended I/O (IC203)
Figure 2-3-4
+5V
+24VA
J207-5
X202
J207-4
SCNCLK J207-3
+5V
/SCNRDY J207-1
/SCND J207-2
M2
Scanner
motor/
driver