Canon LBP 2460 Service Manual - Page 76

CHAPTER 2 C. Scanning System Figure 2-3-4 shows the scanner motor control circuit. DC controller PCB J201-C6 CPU (IC201) /PRNT 64 P10/A0 Gate array (IC205) X202 +5V +24VA Gate array interface bus X1I 40 SCNCK 28 SCNCLK +5V NSRDY 29 /SCNRDY J207-5 J207-4 J207-3 J207-1 Extended I/O interface bus C16 30 /SCND J207-2 M2 Scanner motor/ driver Extended I/O (IC203) Figure 2-3-4 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