Brother mfc8440 - Page 5

MFC-8440/8840D/8840DN, DCP-8040/8045D/8045DN
SERVICE MANUAL
iii
3.2.2 For Parallel Interface Cable Users
(For Windows
®
95/98/98SE/Me/2000 Professional/XP)...................................................2-13
3.2.3 For Windows NT
®
Workstation Version 4.0 Users............................................................2-18
3.2.4 For Network Interface Cable Users
(For Windows
®
95/98/98SE/Me/NT/2000 Professional/XP)..............................................2-20
3.2.5 For USB Interface Cable Users (For Mac
®
OS 8.6 to 9.2 Users)......................................2-23
3.2.6 For USB Interface Cable Users (For Mac
®
OS X 10.1/10.2.1 or greater Users)...............2-24
3.2.7 For Network Interface Cable Users (For Mac
®
OS 8.6 to 9.2 Users) ................................2-25
3.2.8 For Network Interface Cable Users (For Mac
®
OS X 10.1/10.2.1 or greater Users) .........2-26
CHAPTER 3 THEORY OF OPERATION................................................. 3-1
1. ELECTRONICS ...................................................................................................... 3-1
1.1 General Block Diagram ....................................................................................................3-1
1.2 Main PCB Block Diagram.................................................................................................3-2
1.3 Main PCB .........................................................................................................................3-3
1.3.1 CPU.....................................................................................................................................3-3
1.3.2 USB.....................................................................................................................................3-3
1.3.3 IEEE 1284...........................................................................................................................3-4
1.3.4 ROM....................................................................................................................................3-4
1.3.5 Flash ROM..........................................................................................................................3-5
1.3.6 SDRAM ...............................................................................................................................3-5
1.3.7 Optional RAM......................................................................................................................3-6
1.3.8 EEPROM.............................................................................................................................3-7
1.3.9 Reset circuit ........................................................................................................................3-7
1.3.10 Engine I/O ...........................................................................................................................3-7
1.3.11 Panel I/O .............................................................................................................................3-7
1.3.12 Video I/O .............................................................................................................................3-8
1.3.13 Scanner control...................................................................................................................3-8
1.3.14 Power supply.......................................................................................................................3-9
1.4 Engine PCB....................................................................................................................3-10
1.5 Power Supply..................................................................................................................3-11
1.5.1 Low-voltage power supply.................................................................................................3-11
1.5.2 High-voltage power supply................................................................................................3-12
2. MECHANICS ........................................................................................................ 3-13
2.1 Overview of Printing Mechanism....................................................................................3-13
2.2 Scanner Mechanism.......................................................................................................3-14
2.3 Paper Transfer ...............................................................................................................3-15
2.3.1 Paper supply .....................................................................................................................3-15
2.3.2 Paper registration..............................................................................................................3-15
2.3.3 Paper eject........................................................................................................................3-16
2.3.4 Duplex printing ..................................................................................................................3-16
2.4 Sensors ..........................................................................................................................3-17
2.4.1 Cover sensors...................................................................................................................3-17
2.4.2 Toner sensors ...................................................................................................................3-17
2.4.3 Cassette sensor / Paper empty sensor.............................................................................3-18
2.4.4 Paper eject sensor ............................................................................................................3-18
2.4.5 MP-PE sensor ...................................................................................................................3-19
2.4.6 Document cover sensor ....................................................................................................3-19
2.4.7 Document front sensor / Document rear sensor ...............................................................3-20
2.4.8 DX-sensor PCB ASSY.......................................................................................................3-20