C. Scanning System - Canon LBP-3260 Service Manual

CHAPTER 2

C. Scanning System

Figure below shows the scanner motor control circuit.
DC controller PCB
IC201
(CPU)
73
XT1/P07
IC202
(G.A.)
52
DB22
54
SCNCLK
70
X1AO
X202
71
X1AI
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 (IC202), and the /SCNCLK signal is sent to the scanner driver.
When the /PRNT signal sent to the CPU (IC201) on the DC controller becomes "L", the CPU
sets the /SCND signal to "L" through the gate array. When it goes "L", the scanner driver rotates
the scanner motor using the SCNCLK signal. When the scanner motor reaches its prescribed
speed, the scanner driver sets the SCANNER MOTOR READY signal (/SCNRDY) signal to "L".
The CPU on the DC controller PCB monitors the /SCNRDY signal to make sure that the scan-
ner motor runs at the correct speed.
The CPU notifies the video controller of a scanner failure in the following cases:
a. When the /SCNRDY signal does not become "L" within 30 seconds after the scanner motor
starts rotation.
b. When the /SCNRDY signal goes "H" for 1.5 continuous seconds after going "L."
2 - 30
+24VA
+5V
+5V
+5V
Figure 2-3-4
J18
J207-7
-1
-1 -7
-2 /SCNRDY
-6
-3 /SCND -5
-5 /SCNCLK
-3
-4 GND
-4
-6 24VGND -2
Scanner motor
J1-1
-7
-6
M1
M
-5
-3
-4
-2