Engine Controller; Outline - Canon LBP2900 series Service Manual

Chapter 2
SW1
1
IC1
J1
14
IC3
1 5
J2
F-2-21

2.7.2 Engine Controller

2.7.2.1 Outline

The engine controller circuit is used to control the sequence of operation of the machine, and it operates under the control of the CPU found in the engine
controller.
When the machine is turned on and the power supply supplies the engine controller with DC power, the CPU starts to control the operation of the printer.
When the machine is in a standby state, the CPU then drives the various loads (e.g., laser diode, motor, solenoid) according to the print command coming
from the video controller.
The following is a block diagram of the circuit:
* CPU (IC902)
The CPU is a 8-bit single-chip microprocessor IC. The CPU is equipped with both ROM and RAM, and it performs the following as instructed by the
control program stored in the ROM:
1. sequential control of the printer.
2. communicates with the interface controller.
3. controls the power supply circuit.
4. controls the laser/scanner.
5. controls sensors.
6. controls loads (motor, solenoid)
7. detects the presence/absence of a cartridge
2-20
IC4
IC2
J3
1
4
2 1
J4
Sensors
Power supply
PCB
Pick-up
solenoid
Video
Controller
PCB
Engine controller PCB
IC902
CPU
F-2-22
Main motor
Scanner motor
BD circuit
Laser driver
0008-0558