Brother HL-8050N User manual

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Read this manual thoroughly before maintenance work.
Keep this manual in a convenient place for quick and easy reference at all times.
Sep. 2003
SM-PRN043

© Copyright Brother Industries, Ltd. 2003
All rights reserved.
No part of this publication may be reproduced in any form or by any means without permission
in writing from the publisher.
Specifications are subject to change without notice.
Trademarks:
The brother logo is a registered trademark of Brother Industries, Ltd.
Apple, the Apple Logo, and Macintosh are trademarks, registered in the United States and
other countries, and True Type is a trademark of Apple computer, Inc.
Epson is a registered trademark and FX-80 and FX-850 are trademarks of Seiko Epson
Corporation.
Hewlett Packard is a registered trademark and HP Laser Jet is a trademark of Hewlett
Packard Company.
IBM, IBM PC and Proprinter are registered trademarks of International Business Machines
Corporation.
Microsoft and MS-DOS are registered trademarks of Microsoft Corporation.
Windows is a registered trademark of Microsoft Corporation in the U.S. and other countries.

HL-8050N SERVICE MANUAL
i
PREFACE
This service manual contains basic information required for after-sales service of the laser
printer (hereinafter referred to as "this machine" or "the printer"). This information is vital to
the service technician to maintain the high printing quality and performance of the printer.
This service manual covers the HL-8050N printers.
This manual consists of the following chapters:
CHAPTER 1: GENERAL
Features, specifications, etc.
CHAPTER 2: INSTALLATION AND BASIC OPERATION
Installation conditions, Installation procedures, basic operation of the printer
etc.
CHAPTER 3: THEORY OF OPERATION
Basic operation of the mechanical system, the electrical system and the
electrical circuits and their timing information.
CHAPTER 4: DISASSEMBLY AND RE-ASSEMBLY
Procedures for disassembling and re-assembling the mechanical system.
CHAPTER 5: MAINTENANCE
Periodical replacements parts, consumable parts, etc.
CHAPTER 6: TROUBLESHOOTING
Reference values and adjustments, troubleshooting image defects,
troubleshooting malfunctions, etc.
CHAPTER 7: SERVICE MODE
Professional Menu mode and Service Menu mode, etc.
APPENDIX:Serial No. descriptions, page counter, Diameter / circumference of rollers,
Connection diagrams, PCB circuit diagrams, etc.
Information in this manual is subject to change due to improvement or redesign of the product.
All relevant information in such cases will be supplied in service information bulletins
(Technical Information).
A thorough understanding of this printer, based on information in this service manual and
service information bulletins, is required for maintaining its print quality performance and for
improving the practical ability to find the cause of problems.

TABLE OF CONTENTS
ii
TABLE OF CONTENTS
REGULATION.............................................................................................viii
SAFETY INFORMATION...............................................................................x
CHAPTER 1 GENERAL.......................................................................... 1-1
1. FEATURES ...............................................................................................................1-1
2. OVERVIEW ...............................................................................................................1-3
3. SPECIFICATIONS.....................................................................................................1-4
3.1 Printing.............................................................................................................................1-4
3.2 Functions..........................................................................................................................1-5
3.3 Options.............................................................................................................................1-5
3.4 Electrical and Mechanical................................................................................................1-6
3.5 Network............................................................................................................................1-7
3.6 Paper................................................................................................................................1-8
3.6.1 Feedable paper................................................................................................................... 1-8
3.6.2 Print delivery .......................................................................................................................1-9
3.7 Printable Area ................................................................................................................1-10
3.8 Serial No. Descriptions ..................................................................................................1-12
CHAPTER 2 INSTALLATION AND BASIC OPERATION...................... 2-1
1. TO USE THE PRINTER SAFETY .............................................................................2-1
1.1 Installing and Relocating your Printer.............................................................................. 2-1
1.2 Precautions for Power and Ground/Earthed Connections ..............................................2-3
1.3 Operating Precautions..................................................................................................... 2-4
1.4 Notes on Handling Consumables....................................................................................2-5
2. CARTON COMPONENTS.........................................................................................2-7
3. CONTROL PANEL....................................................................................................2-8
3.1 Data LED Indications.......................................................................................................2-8
3.2 Liquid Crystal Display (LCD)............................................................................................2-9
3.3 Panel Buttons Functions................................................................................................ 2-10
4. SETTING UP YOUR PRINTER...............................................................................2-11
4.1 Install the Toner Cartridge .............................................................................................2-11
4.2 Load Paper in the Paper Tray........................................................................................2-13
4.3 Installing the Face-up Output Tray ................................................................................2-15
4.4 Printing a Test Page. .....................................................................................................2-16
4.5 Setting Your Language on the Control Panel................................................................2-17

HL-8050N SERVICE MANUAL
iii
CHAPTER 3 THEORY OF OPERATION................................................ 3-1
1. ELECTRONICS.........................................................................................................3-1
1.1 General Block Diagram.................................................................................................... 3-1
1.2 Main PCB.........................................................................................................................3-2
1.2.1 Outline.................................................................................................................................3-2
1.2.2 Circuit..................................................................................................................................3-4
2. MECHANICS.............................................................................................................3-6
2.1 Summary of Print Process...............................................................................................3-6
2.2 Flow of Print Data.............................................................................................................3-9
2.3 Driving Force Transmission Path................................................................................... 3-10
2.3.1 Main Motor........................................................................................................................ 3-10
2.3.2 Motor ASSY Exit ............................................................................................................... 3-10
2.3.3 Gear Layout ...................................................................................................................... 3-11
2.4 Paper Transport.............................................................................................................3-14
2.4.1 Paper Transport Path........................................................................................................ 3-14
2.4.2 Layout of Paper Transport Path........................................................................................ 3-15
2.5 Actions of Main Functional Components.......................................................................3-17
2.5.1 Paper Cassette ................................................................................................................. 3-17
2.5.2 Paper Feeder.................................................................................................................... 3-20
2.5.3 Engine............................................................................................................................... 3-22
2.5.4 Fuser................................................................................................................................. 3-25
2.5.5 500 Paper Exit & Option Face Up Tray ............................................................................ 3-27
2.5.6 Drive ................................................................................................................................. 3-28
2.5.7 Electrical .......................................................................................................................... 3-29
2.6 Control............................................................................................................................3-31
2.6.1 Control of Paper Size........................................................................................................ 3-31
2.6.2 ROS Control...................................................................................................................... 3-31
2.6.3 Fuser Control.................................................................................................................... 3-32
2.7 Schematic Diagrams of Safety System .........................................................................3-33
CHAPTER 4 DISASSEMBLY AND RE-ASSEMBLY ............................. 4-1
1. SAFETY PRECAUTIONS..........................................................................................4-1
2. DISASSEMBLY FLOW..............................................................................................4-2
3. DISASSEMBLY PROCEDURE .................................................................................4-3
3.1 Drum Unit.........................................................................................................................4-3
3.2 Paper Cassette 150.........................................................................................................4-3
3.3 Paper Cassette 550....................................................................................................... 4-10
3.4 Face-up Output Tray ASSY ..........................................................................................4-16
3.5 Stopper FSR/Cover Rear 500........................................................................................4-16
3.6 Disassembly of the Cover Rear 500..............................................................................4-17
3.7 Cover Rear.....................................................................................................................4-20
3.8 Cover Right....................................................................................................................4-21
3.9 Cover Left.......................................................................................................................4-22
3.10 Cover Exit 500................................................................................................................4-22
3.11 500 Exit ASSY................................................................................................................4-23
3.12 Cover Top/Operation Panel...........................................................................................4-29
3.13 Cover Front ...................................................................................................................4-31

TABLE OF CONTENTS
iv
3.14 Fan Main........................................................................................................................4-31
3.15 Chute Transfer...............................................................................................................4-32
3.16 Lever Fuser LH/Lever Fuser RH....................................................................................4-33
3.17 150 Feeder ASSY..........................................................................................................4-34
3.18 550 Feeder ASSY..........................................................................................................4-41
3.19 Sensor Low Paper/Actuator/Plate CST Lock/Stopper Tray R/ Stopper Tray L.............4-46
3.20 Guide Tray Right............................................................................................................4-47
3.21 Guide Tray Left ..............................................................................................................4-47
3.22 Duct Front/Fan SUB.......................................................................................................4-48
3.23 ROS ASSY.....................................................................................................................4-49
3.24 Shield Plate ROS...........................................................................................................4-50
3.25 Main Motor.....................................................................................................................4-50
3.26 Guide CRU Left..............................................................................................................4-52
3.27 Guide ASSY CRU R ......................................................................................................4-54
3.28 Power Switch .................................................................................................................4-55
3.29 Interlock SW Rear..........................................................................................................4-55
3.30 Gear ASSY Housing......................................................................................................4-56
3.31 Gear ASSY Plate/Gear 9...............................................................................................4-57
3.32 PWBA Exit Motor ...........................................................................................................4-58
3.33 LVPS..............................................................................................................................4-59
3.34 HVPS/MCU, FFC ASSY ESS........................................................................................4-60
3.35 PWBA ESS ....................................................................................................................4-61
4. PACKING ................................................................................................................4-62
5. GUIDELINES FOR LEAD FREE SOLDER..............................................................4-63
6. HARNESS ROUTING..............................................................................................4-66
CHAPTER 5 PERIODIC MAINTENANCE............................................... 5-1
1. REPALACING THE TONER CARTRIDGE (TN-1700) ..............................................5-1
1.1 Toner Cartridge Handling Precautions ............................................................................5-1
1.2 Replacing the Toner Cartridge......................................................................................... 5-2
2. REPALACING THE FUSER UNIT & TRANSFER ROLL CARTRIDGE (FP-8000) ...5-4
2.1 Fuser Unit & Transfer Roll Cartridge Handling Precautions...............................................5-4
2.2 Replacing the Fuser Unit & Transfer Roll Cartridge ...........................................................5-4
3. REPALACING THE FEED ROLLER ............................................................................5-9
3.1 Replacing the Feed Roller.................................................................................................5-10
4. CLEANING THE PRINTER ........................................................................................5-13
4.1 Cleaning the Outside of the Printer................................................................................... 5-13
4.2 Cleaning the Interior..........................................................................................................5-14
4.3 Cleaning the Feeder Roller...............................................................................................5-14
4.4 If the Printer Will Not Be Used for a Long Time................................................................5-15

HL-8050N SERVICE MANUAL
v
CHAPTER 6 TROUBLESHOOTING....................................................... 6-1
1. PRPGRESSING WITH THE TROUBLESHOOTING.................................................6-1
1.1 Flow of Troubleshooting...................................................................................................6-1
1.2 Preparatory Requirements...............................................................................................6-2
1.3 Cautions for Service Operations......................................................................................6-3
1.4 Cautions for FIP Use........................................................................................................6-4
2. LEVEL 1 FIP..............................................................................................................6-5
2.1 Level 1 FIP.......................................................................................................................6-5
2.2 Flow of Level 1 FIP ..........................................................................................................6-5
2.3 Error/Status Code List......................................................................................................6-6
3. LEVEL 2 FIP..............................................................................................................6-9
3.1 Level 2 FIP.......................................................................................................................6-9
4. ERROR CODE FIP..................................................................................................6-10
4.1 Level 1 FIP.....................................................................................................................6-10
4.2 Level 2 FIP.....................................................................................................................6-28
5. IMAGE QUALITY TROUBLE...................................................................................6-44
5.1 Entry Chart Image Quality Troubleshooting...................................................................6-44
5.2 Image Quality FIP .......................................................................................................... 6-46
6. JUDGEMENT OF PRINT CONSISTENCY..............................................................6-65
7. PREVENTIVE MAIN MAINTENANCE.....................................................................6-70
CHAPTER 7 SERVICE MODE................................................................ 7-1
1. ENTERING HIDDEN FUNCTION MENU MODES....................................................7-1
2. PROFESSIONAL MENU MODE ...............................................................................7-2
2.1 Enabling and Disabling Professional Menu Mode........................................................... 7-2
2.2 Function Table .................................................................................................................7-3
3. SERVICE MENU MODE............................................................................................7-8
3.1 Entering the Service Menu Mode ....................................................................................7-8
3.2 Function Table .................................................................................................................7-8
4. OTHER HIDDEN FUNCTION MENUS....................................................................7-11
4.1 Hidden Function Menus Enabled by Pressing Switch (es) When Turning the Machine on.
.......................................................................................................................................7-11
4.2 Parts life Reset Function................................................................................................7-11
5. HOW TO USE THE SELF-DIAGNOSTICS TOOLS ................................................7-12
5.1 Troubleshooting for Printer won’t print...........................................................................7-12
5.2 Diagnostics.....................................................................................................................7-13
5.3 Printer Information .........................................................................................................7-15
6. HOW TO REWRITE HL-8050N FLASH ROM.........................................................7-16
7. NVRAM BACKUP....................................................................................................7-17

TABLE OF CONTENTS
vi
CHAPTER 8 PLUG/JACK(P/J) CONNECTOR LOCATIONS ................ 8-1
1. CONNECTOR [P(PLUG)/J(JACK)]............................................................................8-1
1.1 List of P/J .........................................................................................................................8-1
1.2 P/J Layout Diagram .........................................................................................................8-3
APPENDIX
1. CONNECTION WIRING DIAGRAM ......................................................................... A-1
1.1 Connection Wiring Diagram.............................................................................................A-1
1.1.1 Symbols in the General Connection Wiring Diagram ..........................................................A-1
1.1.2 General Wiring Diagram......................................................................................................A-2
1.2 Interconnection Wiring Diagram of Parts.........................................................................A-3
1.2.1 Instructions for the Use of the Interconnection Wiring Diagram of Parts.............................A-3
1.2.2 Configuration of the Interconnection Wiring Diagram of Parts.............................................A-4
2. HOW TO KNOW PAGE COUNTER & PARTS LIFE.............................................. A-13
1.1 Printing Out of the Print Configuration Page..................................................................A-13
1.2 How to Read the Page Counter & the Parts Life...........................................................A-13
3. NOTE TO REMEMBER ABOUAT TONER CARTRIDGE....................................... A-15