Brother MFC-4820C User manual

FACSIMILE EQUIPMENT
SERVICE MANUAL
MODEL: MFC4820C/MFC4420C

i
PREFACE
This publication is a Service Manual covering the specifications, construction, theory of operation,
and maintenance of the Brother facsimile equipment. It includes information required for field
troubleshooting and repair--disassembly, reassembly, and lubrication--so that service personnel
will be able to understand equipment function, to rapidly repair the equipment and order any
necessary spare parts.
To perform appropriate maintenance so that the facsimile equipment is always in best condition
for the customer, the service personnel must adequately understand and apply this manual.
This manual is made up of eight chapters and appendices.
SAFETY INSTRUCTIONS
CHAPTER 1 PARTS NAMES & FUNCTIONS
CHAPTER 2 SPECIFICATIONS
CHAPTER 3 SETTING UP OF THE MACHINE
CHAPTER 4 THEORY OF OPERATION
CHAPTER 5 ROUTINE MAINTENANCE
CHAPTER 6 DISASSEMBLY/REASSEMBLY
CHAPTER 7 MAINTENANCE MODE
CHAPTER 8 TROUBLESHOOTING
Appendix 1. Serial No. Descriptions
Appendix 2. Software Installation
Appendix 3. EEPROM Customizing Codes
Appendix 4. Firmware Switches (WSW)
Appendix 5. Re-packing Instructions
Appendix 6. Wiring Diagram
Appendix 7. Circuit Diagrams
This manual describes the models and their versions to be destined for major countries. The specifications
and functions are subject to change depending upon each destination.

CHAPTER 4 THEORY OF OPERATION
CONTENTS
4.1 OVERVIEW ......................................................................................................................4-1
4.2 MECHANISMS.................................................................................................................4-2
4.2.1 Document Scanner Mechanism...........................................................................4-4
4.2.2 Paper Feeding Mechanism ..................................................................................4-6
4.2.2.1 Auto Sheet Feeder (ASF) mechanism.........................................................4-7
4.2.2.2 Paper feeding and ejection mechanism.......................................................4-9
4.2.3 Printing mechanism............................................................................................4-11
4.2.3.1 Ink supply and ink jet mechanism..............................................................4-12
4.2.3.2 Head cap mechanism ................................................................................4-21
4.2.3.3 Purging mechanism ...................................................................................4-22
4.2.3.4 Carriage drive mechanism.........................................................................4-29
4.2.4 Sensors and Actuators.......................................................................................4-31
4.3 CONTROL ELECTRONICS...........................................................................................4-34
4.3.1 Configuration......................................................................................................4-34

CHAPTER 6 DISASSEMBLY/REASSEMBLY
CONTENTS
6.1 DISASSEMBLY/REASSEMBLY .....................................................................................6-1
Safety Precautions.......................................................................................................6-1
Tightening Torques...........................................................................................................6-2
Preparation ..................................................................................................................6-3
How to Access the Object Component........................................................................6-3
Disassembly Flowchart................................................................................................6-4
6.1.1 Draining the Ink from the Ink Tubes
--This must be performed before removing the print head unit or engine unit-- ..6-5
6.1.2 Print Head Unit.....................................................................................................6-6
6.1.3 Bottom Plate, Main Insulation Sheet, and EMC Plates (USB and MJ)..............6-13
6.1.4 Power Supply Insulation Sheet, Battery Cover (Rear Cover S), and
Backup Battery...................................................................................................6-16
6.1.5 Rear Cover L, Enclosure Cover, Power Supply PCB, and NCU PCB...............6-17
6.1.6 USB PCB, Main PCB, Modular PCB*, and Driver PCB.....................................6-19
6.1.7 Document Cover ................................................................................................6-23
6.1.8 Scanner Unit and Control Panel.........................................................................6-24
6.1.9 Upper Cover and ASF Cover R..........................................................................6-26
6.1.10 Media Module and Handset Mount (Side Cover)...............................................6-28
6.1.11 Speaker..............................................................................................................6-29
6.1.12 Auto Sheet Feeder (ASF)...................................................................................6-30
6.1.13 Engine Unit and Purge Unit................................................................................6-33
6.1.14 Ink Cartridge Support Base, Ink Absorber Case, Ink Slot Cover, and
Air Pump & Motor Module..................................................................................6-41
6.1.15 Routing of the Harnesses and Flat Cables........................................................6-44
6.2 LONG-PERIOD STORAGE ...........................................................................................6-49

6-1
6.1 DISASSEMBLY/REASSEMBLY


Safety Precautions
To prevent the creation of secondary problems through mishandling, observe the following
precautions for maintenance work.
(1) Unplug the power cord from the power outlet before replacing parts or units. When accessing
to the power-related sections, be sure to unplug the power cord from the power outlet.
(2) Be careful not to lose screws, washers or any other parts removed for parts replacement.
(3) When using soldering irons and other heat-generating tools, take care not to damage the resin
parts such as wires, PCBs, and covers.
(4) Before handling the PCBs, touch a metal portion of the machine to discharge the static
electricity in your body; otherwise, the electronic parts may be damaged.
(5) When transporting PCBs, be sure to wrap them in conductive sheets such as aluminum foil.
(6) If any of the self-tapping (Taptite) screws are removed, be sure to reinsert them correctly.
(7) Tighten screws to the torque values listed on the next page.
(8) When connecting or disconnecting cables, hold the connector bodies not the cables themselves.
If the connector has a lock, always slide the lock to unlock the connector.
(9) After repairs, check not only the repaired portion but also that the connectors and other related
portions function properly before performing any operational checks.
(10) The print head unit will start head locking operation five seconds after the printing is finished.
Head locking operation takes from 5 to 10 seconds. NEVER unplug the power cord before the
print head unit completes the head locking operation; doing so will render the print head unit
unusable, and therefore require replacement.
When you receive the machine from the user or when you pack it to send it back to the user,
check the head locking state.

CHAPTER 8 ERROR INDICATION AND TROUBLESHOOTING
CONTENTS
8.1 ERROR INDICATION.......................................................................................................8-1
8.1.1 Equipment Errors .................................................................................................8-1
[ 1 ] Error messages on the LCD ........................................................................8-1
[ 2 ] Error codes shown in the "MACHINE ERROR X X " message....................8-3
8.1.2 Communications Errors........................................................................................8-7
8.2 TROUBLESHOOTING...................................................................................................8-13
8.2.1 Introduction.........................................................................................................8-13
8.2.2 Precautions ........................................................................................................8-13
8.2.3 Checking prior to Troubleshooting .....................................................................8-13
8.2.4 Troubleshooting Procedures..............................................................................8-15
[ 1 ] Control panel related..................................................................................8-15
[ 2 ] Telephone related......................................................................................8-15
[ 3 ] Communications related............................................................................8-16
[ 4 ] Paper feeding related.................................................................................8-16
[ 5 ] Print-image related.....................................................................................8-17
[ 6 ] PC-driven printing ......................................................................................8-20
[ 7 ] SmartMedia, Compact Flash, or Memory Stick driven printing..................8-21
[ 8 ] Others ........................................................................................................8-21
Cleaning the purge unit ........................................................................................8-22
Cleaning the print head unit..................................................................................8-22
8.3 JAMS..............................................................................................................................8-23
8.3.1 Paper is Jammed inside the Machine ................................................................8-23
8.3.2 Paper is Jammed in the Paper Tray...................................................................8-24
8.3.3 Paper is Jammed inside the Paper Tray............................................................8-24

Brother MFC-4420C MFC-4820C service manual
Brother MFC-4420C MFC-4820C service manual
Brother MFC-4420C MFC-4820C service manual
Brother MFC-4420C MFC-4820C service manual
Brother MFC-4420C MFC-4820C service manual
Brother MFC-4420C MFC-4820C service manual
Brother MFC-4420C MFC-4820C service manual
Brother MFC-4420C MFC-4820C service manual
Brother MFC-4420C MFC-4820C service manual