Brother Facsimile Equipment MFC7420 - Manual (Page 45)

Confidential
CHAPTER 3 THEORY OF OPERATION
This chapter gives an overview of the scanning and printing mechanisms as well as the sensors,
actuators, and control electronics. It aids in understanding the basic principles of operation as
well as locating defects for troubleshooting.
CONTENTS
3.1 OVERVIEW ...................................................................................................................... 3-1
3.2 MECHANICAL COMPONENTS....................................................................................... 3-2
3.2.1 Scanner Mechanism ............................................................................................ 3-3
3.2.2 Printing Mechanism.............................................................................................. 3-6
3.2.2.1 Paper supply ................................................................................................ 3-6
3.2.2.2 Push-up function of paper tray..................................................................... 3-8
3.2.2.3 Paper registration....................................................................................... 3-10
3.2.2.4 Paper eject ................................................................................................. 3-11
3.2.2.5 Drum unit.................................................................................................... 3-11
3.2.2.6 Toner cartridge........................................................................................... 3-12
3.2.2.7 Print process .............................................................................................. 3-15
3.2.3 Sensors and Actuators ....................................................................................... 3-18
3.3 CONTROL ELECTRONICS........................................................................................... 3-19
3.3.1 Components ....................................................................................................... 3-19