Canon LBP-2000, Service Manual

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CHAPTER 2
2 - 8
2 . Operation within the block
a . CPU
The CPU is an 8-bit microprocessor. It is a single-chip type, possessing a built-in ROM and RAM;
it performs the following operation of the Printer using ASIC according to the control program
stored in ROM.
1) controlling the sequence of operation of the printer engine
2) controlling the registration sensor/delivery sensor
3) controlling the drive of the main motor/fan motor
4) controlling the cassette pickup clutch/registration clutch
5) controlling the multifeeder pickup solenoid
6) communicating with the paper feeder
b . ASIC
1) controlling the communication with the video controller PCB
2) controlling the high-voltage power supply circuit
3) controlling the laser/scanner
4) controlling the fixing heater
5) controlling the multifeeder paper sensor/paper size detecting switch
c . Reset IC
The reset IC monitors the +3.3V voltage and resets the CPU in a specific time if the power supply
voltage r2.7 V after the power is turned on or if it drops below +2.7 V while power is
s u p p l i e d .
d . Heater control circuit
For details, see C. ‘Controlling the Fixing Mechanisms.’
e . High voltage power supply circuit
For details, see D. ‘High-Voltage Power Supply Circuit.’
f . Low-voltage power supply circuit
For details, see E. ‘Low-Voltage Power Supply Circuit.’