Brother HL-3450CN Service Manual

Brother Color Laser Printer

SERVICE MANUAL

MODEL: HL-3450CN

Read this manual thoroughly before commencing any maintenance work.
Keep this manual in a convenient place for quick and easy reference at all times.

January, 2002
SM-PRN028

© Copyright Brother 2002

All rights re served.
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-3450CN SERVICE MANUAL

i

PREFACE

This service manual contains basic information required for after-sales service of the color laser printer
(here-in-after 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-3450CN color laser printer.
This manual consists of the following chapters:

CHAPTER 1: OUTLINE OF PRODUCT

Features, parts names, internal structure, and description of the control panel.

CHAPTER 2: SPECIFICATIONS

Specifications, etc.

CHAPTER 3: INSTALLATION

Installation conditions and installation procedures.

CHAPTER 4: STRUCTURE OF SYSTEM COMPONENTS

Basic operation of the mechanical system, the electrical system and the electrical
circuits and their timing information.

CHAPTER 5: CONTROL PANEL OPERATION

Operation and setting procedures on the control panel.

CHAPTER 6: PERIODIC MAINTENANCE

Description of periodic maintenance parts and procedures for periodic replacement
and cleaning.

CHAPTER 7: DISASSEMBLY

Procedures for replacement of the mechanical system parts.

CHAPTER 8: TROUBLESHOOTING

Description of error messages on the control panel, troubleshooting image failure,
etc.

APPENDICES : SERIAL NO. DESCRIPTIONS, ETC.

Information in this manual is subject to change due to improvement or re-design 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

TABLE OF CONTENTS

REGULATIONS..................................................................................vi

SAFETY INSTRUCTIONS................................................................viii

SHIPMENT OF THE PRINTER.........................................................xiii

CHAPTER 1 PRODUCT OUTLINE ................................................. 1-3

1. FEATURES.....................................................................................................1-3

2. PARTS NAMES & FUNCTIONS.....................................................................1-6

3. INTERNAL STRUCTURE...............................................................................1-8

4. DESCRIPTION OF CONTROL PANEL ..........................................................1-9

4.1 Video Controller Mode .........................................................................................................1-9

4.2 Engine Controller Mode .......................................................................................................1-9

CHAPTER 2 SPECIFICATIONS...................................................... 2-3

1. RATING ..........................................................................................................2-3

2. GENERAL SPECIFICATIONS........................................................................2-4

2.1 Printing.................................................................................................................................2-4

2.2 Functions .............................................................................................................................2-4

2.3 Electrical and Mechanical ....................................................................................................2-5

2.4 Paper....................................................................................................................................2-6

2.5 Printing Area ........................................................................................................................2-8

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3. ENVIRONMENTAL CONDITIONS.................................................................2-11

3.1 Ambient Temperature / Humidity / Altitude ........................................................................2-11

CHAPTER 3 INSTALLATION ......................................................... 3-3

1. CONDITIONS REQUIRED FOR INSTALLATION...........................................3-3

1.1 Environmental Conditions....................................................................................................3-3

1.2 Basic Layout of Printer Set-up Location...............................................................................3-3

2. UNPACKING...................................................................................................3-5

2.1 Unpacking the Printer ..........................................................................................................3-5

2.2 Unpack the Starter Kit..........................................................................................................3-7

3. INSTALLATION WORK ..................................................................................3-8

3.1 Install the Oil Bottle and Fuser Cleaner ...............................................................................3-8

3.2 Install the OPC Belt Cartridge..............................................................................................3-9

3.3 Install the Toner Cartridge into the Printer.........................................................................3-11

3.4 Install the Media Cassette and Adaptor.............................................................................3-12

3.5 Test Print............................................................................................................................3-14

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ii

HL-34500CN SERVICE MANUAL

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS.............. 4-3

1. BASIC STRUCTURE......................................................................................4-3

1.1 Mechanical Structure ...........................................................................................................4-3

1.2 Basic Mechanism of Color Printing......................................................................................4-5

1.3 Structure of the OPC Belt ....................................................................................................4-7

1.4 Print System and Transfer System ......................................................................................4-8

1.5 Scanning System...............................................................................................................4-23

1.6 Paper Transportation System ............................................................................................4-25

1.7 Fusing Unit.........................................................................................................................4-26

2. STRUCTURE OF THE CONTROL SYSTEM.................................................4-28

2.1 Basic Structure - Electrical System and Functions............................................................4-28

2.2 Control System - Control of the Print Process ...................................................................4-37

2.3 Main PCB (Video Controller PCB) .....................................................................................4-46

2.4 Low-voltage Power Supply Unit.........................................................................................4-60

2.5 High-voltage Power Supply Unit ........................................................................................4-63

2.6 Connection Diagram ..........................................................................................................4-65

CHAPTER 5 CONTROL PANEL OPERATION............................... 5-3

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1. PANEL LAYOUT.............................................................................................5-3

2. VIDEO CONTROLLER MODE........................................................................5-4

2.1 Configuration of Operational Mode......................................................................................5-4

2.2 Line Test Mode ....................................................................................................................5-5

2.3 DRAM Test Mode ................................................................................................................5-9

2.4 Test Print Mode..................................................................................................................5-10

2.5 NVRAM Reset Mode..........................................................................................................5-10

3. ENGINE CONTROLLER MODE...................................................................5-11

3.1 Configuration of Operational Mode....................................................................................5-11

3.2 Operation of Normal Mode.................................................................................................5-13

3.3 Service Mode.....................................................................................................................5-20

3.4 Adjustment Work Procedures ............................................................................................5-44

CHAPTER 6 PERIODIC MAINTENANCE....................................... 6-3

1. GENERAL.......................................................................................................6-3

1.1 Handling Precautions...........................................................................................................6-3

1.2 List of Maintenance Tools

1.3 List of Consumables for Maintenance..................................................................................6-5

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6-4

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2. PERIODIC MAINTENANCE CLEANING .........................................................6-6

2.1 Cleaning the Register Roller................................................................................................6-9

2.2 Cleaning the Paper Guide..................................................................................................6-10

2.3 Cleaning the Paper Exit Roller...........................................................................................6-11

2.4 Cleaning the Transfer Roller..............................................................................................6-12

iii

TABLE OF CONTENTS

2.5 Cleaning the Paper Discharger..........................................................................................6-13

2.6 Cleaning the OPC Belt Cartridge.......................................................................................6-14

2.7 Cleaning the Transfer Drum...............................................................................................6-15

2.8 Cleaning the Dustproof Glass in the Laser Unit.................................................................6-16

2.9 Cleaning the Printer Interior...............................................................................................6-17

2.10 Cleaning the Oil Pad........................................................................................................6-18

3. PERIODIC MAINTENANCE PARTS..............................................................6-19

4. PERIODIC MAINTENANCE PROCEDURES ................................................6-21

4.1 OPC Belt Cartridge Replacement......................................................................................6-21

4.2 Fusing Unit Replacement...................................................................................................6-23

4.3 Transfer Roller Replacement.............................................................................................6-26

4.4 Paper Discharger Replacement.........................................................................................6-28

4.5 Drum Cleaner Replacement ..............................................................................................6-30

4.6 Ozone Filter Replacement .................................................................................................6-32

4.7 Paper Feeding Roller and Separator Pad Replacement....................................................6-33

4.8 Transfer Drum Replacement..............................................................................................6-34

4.9 Oil Pad Replacement.........................................................................................................6-35

CHAPTER 7 DISASSEMBLY & RE-ASSEMBLY............................ 7-4

1. BEFORE STARTING DISASSEMBLY............................................................7-4

1.1 Precautions..........................................................................................................................7-4

1.2 Preparation of Disassembly.................................................................................................7-4

2. PARTS NAME.................................................................................................7-6

2.1 Cover ...................................................................................................................................7-6

2.2 Circuit Boards (PWBs).........................................................................................................7-7

2.3 Motor Units...........................................................................................................................7-7

2.4 Clutches...............................................................................................................................7-8

2.5 Sensors................................................................................................................................7-8

3. DISASSEMBLY FLOW................................................................................... 7-9

4. DISASSEMBLY PROCEDURE.....................................................................7-10

4.1 Right Side of the Printer.....................................................................................................7-10

4.2 Top of the Printer ...............................................................................................................7-23

4.3 Left Side of the Printer .......................................................................................................7-32

4.4 Paper Exit Unit...................................................................................................................7-42

4.5 Front of the Printer.............................................................................................................7-47

4.6 Rear of the Printer..............................................................................................................7-50

4.7 Fusing Unit.........................................................................................................................7-54

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iv

HL-34500CN SERVICE MANUAL

v

CHAPTER 8 TROUBLESHOOTING ............................................... 8-3

1. OUTLINE OF TROUBLESHOOTING .............................................................8-4

2. OPERATOR CALL..........................................................................................8-5

2.1 Video Controller Mode .........................................................................................................8-5

2.2 Engine Controller Mode .......................................................................................................8-8

3. PAPER TRANSPORT ERROR.....................................................................8-10

3.1 Feed Jam...........................................................................................................................8-10

3.2 Inner Jam...........................................................................................................................8-11

3.3 Outer Jam ..........................................................................................................................8-13

3.4 Others ................................................................................................................................8-13

4. SERVICE CALL............................................................................................8-14

4.1 Video Controller Mode .......................................................................................................8-15

4.2 Engine Controller Mode .....................................................................................................8-18

5. IMAGE FAILURE..........................................................................................8-47

APPENDIX 1 ...................................................................................A-1

APPENDIX 2 ...................................................................................A-6

APPENDIX 3 ...................................................................................A-7

APPENDIX 4 ...................................................................................A-8

APPENDIX 5 .................................................................................A-11

APPENDIX 6 .................................................................................A-14

APPENDIX 7 .................................................................................A-21

APPENDIX 8 .................................................................................A-36

APPENDIX 9 .................................................................................A-38

REGULATIONS

REGULATIONS

LASER SAFETY (FOR 110-120 V MODEL ONLY)

This printer is certified as a Class I laser product under the U.S. Department of Health and Human
Services (DHHS) Radiation Performance Standard according to the Radiation Control for Health and
Safety Act of 1968. This means that the printer does not produce hazardous laser radiation.

Since radiation emitted inside the printer is completely confined within protective housings and external
covers, the laser beam cannot escape from the machine during any phase of user operation.

FDA REGULATIONS (FOR 110-120 V MODEL ONLY)

U.S. Food and Drug Administration (FDA) has implemented regulations for laser products
manufactured on and after August 2, 1976. Compliance is mandatory for products marketed in the
United States. One of the following labels on the back of the printer indicates compliance with the FDA
regulations and must be attached to laser products marketed in the United States.

Caution

Use of controls, adjustments or performance of procedures other than those specified in this manual
may result in hazardous radiation exposure.

vi

HL-3450CN SERVICE MANUAL

IEC 60825 SPECIFICATION (FOR 220-240 V MODEL ONLY)

This printer is a Class 1 laser product as defined in IEC 60825 specifications. The label shown below
is attached in countries where required.

This printer has a Class 3B Laser Diode which emits invisible laser radiation in the Scanner Unit. The
Scanner Unit should not be opened under any circumstances.

Caution

Use of controls, adjustments or performance of procedures other than those specified in this manual
may result in hazardous radiation exposure.

The following caution label is attached near the laser unit.

5mW

780nm-800nm

DANGER­VORSICHT

DANGER­PELIGRO-

INVISIBLE LASER RADIATION WHEN OPEN.
AVOID DIRECT EXPOSURE TO BEAM.

UNSICHTBARE LASERSTRAHLUNG, WENN ABDECKUNG

-

GEÖFFNET UND SICHERHEITSVERRIEGELUNG
ÜBERBRÜCKT. NICHT DEM STRAHL AUSSETZEN.

RAYON LASER INVISIBLE LORS DE L’OUVER TURE.
EVITER L’EXPOSITION DIRECTE.

RADIACION LASER INVISIBLE AL ABRIR. EVITAR
LA EXPOSICION DIRECTA AL HAZ.

MAS

For Finland and Sweden
LUOKAN 1 LASERLAITE
KLASS 1 LASER APPARAT

Varoitus! Laitteen käyttäminen muulla kuin tässä käyttöohjeessa mainitulla tavalla saattaa altistaa
käyttäjän turvallisuusluokan 1 ylittävälle näkymättömälle lasersäteilylle.

Varning – Om apparaten används på annat sätt än i denna Bruksanvisning specificerats, kan
användaren utsättas för osynlig laserstrålning, som överskrider gränsen för laserklass 1.

vii

SHIPMENT OF THE PRINTER

SAFETY INSTRUCTIONS

SAFETY PRINCIPLE

1) Before starting any operations, read this manual thoroughly. Especially read the safety instructions
in this section carefully and ensure that you understand the contents.

2) Perform all the operations by following the procedures described in this manual. Follow all the
cautions and warnings set out in the procedures and on safety labels affixed to the machine.
Failure to do so may result in human injury or equipment damage.

3) Perform only the procedures explained in this manual. Refrain from opening or touching any
portions that are not related to your required operation(s).

4) Repair and replacement of parts should be performed by trained and qualified persons only.
Operators should not attempt to do such repair or replacement work.

5) It must be appreciated that the above-mentioned cautions and warnings do not cover every
circumstance because it is impossible to evaluate all the conditions of repair situations.

SPECIAL SAFETY INFORMATION

Introductory Information

Cautions and warnings are made clear by them following a ‘Safety Alert Symbol’ or ‘Signal Word’ such
as DANGER, WARNING and CAUTION.

<SAFETY ALERT SYMBOL>
This is the safety alert. When you find this symbol placed on the equipment or marked in this manual,

be aware of the potential of human injuries. Follow the recommended precautions and safety
operation practices.

<Understanding Signal Words>
DANGER is used to indicate the presence of a hazard which will cause severe human injuries or a fatal
accident if the warning is ignored.
WARNING is used to indicate the presence of a hazard or unsafe practices which may cause severe
human injuries or a fatal accident if the warning is ignored.
CAUTION is used to indicate the presence of a hazard or unsafe practices which may cause minor
human injuries if the warning is ignored. CAUTION also calls your attention to safety messages in this
manual.

<Follow Safely Instructions>
Carefully read all the safety messages set out in this manual and also in the safety warning signs
placed on the equipment. In this manual, the safety instructions (safety alert symbols and signal
words) are enclosed in a rectangular enclosure to bring them to your attention. Keep the safety signs
on the equipment in good condition and ensure none are missing or damaged. Replace the safety
signs if unreadable or damaged. Learn how to operate the equipment and how to use the controls
properly. Do not let anyone operate this equipment without following the instructions. Keep the
equipment in proper working condition. Unauthorized modification to the equipment may impair the
function & safety and affect the life of the equipment.
Listed below are the various kinds of “WARNING” messages contained in this manual.

<Caution for the batteries>
There is a danger of explosion if the battery is incorrectly replaced.
Do not replace the battery.
Do not disassemble, recharge or dispose of in fire.
Used battery should be disposed of according to local regulations.

viii

HL-3450CN SERVICE MANUAL

WARNING

HAZARDOUS VOLTAGE

May cause serious injuries or fatal accidents. Voltage is now applied from the power
supply of printer. There is a danger of electrical shock if you touch the active area
inside the printer.

Be sure to turn the power supply switch OFF and pull the plug out from the power
outlet before starting maintenance work on the printer.

WARNING

HARMFUL OZONE GAS

Inhalation of an excessive amount of ozone gas may adversely affect the respiratory
organs.

An Ozone Filter is fitted to this printer to reduce the exhausted ozone. This filter
must be replaced with a new filter periodically in accordance with the manual
supplied with the printer.

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WARNING

HOT SURFACE

The Fusing Unit reaches a temperature of approx.160°C and adjacent parts are also
very hot.

When you need to change the cleaning pad or remove jammed paper, wait about 20
minutes after opening the paper exit unit to allow the unit to cool down.

CAUTION

ROTATING PARTS

Be aware of the potential danger of various rollers and take care not to get your
fingers or hand caught in the machine, this can cause serious injuries. Note that the
exit roller that ejects the printed paper rotates during printing.

Be careful not to get your hair, fingers, hands, sleeve or necktie caught in the
machine while operating the machine.

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ix

SHIPMENT OF THE PRINTER

CAUTION

HAZARDOUS POWDER

Toner is a fine powder which can cause a powder explosion if disposed of into a fire.
Under no circumstances dispose of toner into a fire.

CAUTION

HAZARDOUS POWDER

Toner is a fine powder which may cause irritation to the eyes and respiratory organs
if inhaled.

Handle the toner cartridge, waste toner pack and developing unit carefully so as not
to spill the toner.

CAUTION

POWER CORDS & PLUGS

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This printer is equipped with a 3-wire power cord fitted with a 3-pronged plug (bi­polar plug with grounding) for the user’s safety.

Use these power cords in conjunction with a properly grounded electrical outlet to
avoid an electrical shock.

CAUTION

SAFETY INTERLOCK

The front cover, paper exit unit and transfer unit of this printer have electrical safety
interlocks to turn the power off whenever they are opened. Do not attempt to
circumvent these safety interlocks.

CAUTION

N Do not step on or lean against the media cassette. It may cause the product to tilt

or fall over and result in injuries.

N Do not lean against or apply any excessive force to the media cassette or open

covers, otherwise it may cause the product to tilt or fall over and result in injuries.

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x

HL-3450CN SERVICE MANUAL

CAUTION

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Do not lean against or apply any excessive force to the paper cassette, open cover
of Duplex unit. Otherwise it may cause the product to decline or fall down and result
in the injuries.

xi

SHIPMENT OF THE PRINTER

1

2

4 3

<Label Location>

1. Hot Caution Label

5

WARNING WARNUNG

Hot surface.
Avoid contact.

Heiße oberfiäche.
Bei beseitigung.

AVERTISSEMENT

Surface chaude.
Eviter tout contact.

2. Laser Caution Label

DANGER­VORSICHT

DANGER­PELIGRO-

5mW

780nm-800nm

INVISIBLE LASER RADIATION WHEN OPEN.
AVOID DIRECT EXPOSURE TO BEAM.

UNSICHTBARE LASERSTRAHLUNG, WENN ABDECKUNG

-

GEÖFFNET UND SICHERHEITSVERRIEGELUNG
ÜBERBRÜCKT. NICHT DEM STRAHL AUSSETZEN.

RAYON LASER INVISIBLE LORS DE L’OUVER TURE.
EVITER L’EXPOSITION DIRECTE.

RADIACION LASER INVISIBLE AL ABRIR. EVITAR
LA EXPOSICION DIRECTA AL HAZ.

MAS

xii

HL-3450CN SERVICE MANUAL

3. Rating Label

4. Operation Label

(For US)

(For Europe)

5. Jam Label

xiii

SHIPMENT OF THE PRINTER

SHIPMENT OF THE PRINTER

If for any reason you must ship the printer, carefully package the printer to avoid any damage during
transit. It is recommended that you save and use the original packaging. The printer should also be
adequately insured with the carrier.

CAUTION

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N When shipping the printer, remove the toner cartridges, the OPC belt cartridge

and the waste toner pack from the printer to prevent toner spill in the printer or
damage of the toner cartridge and the OPC belt cartridge.

N When shipping the printer, remove the oil bottle and the fuser cleaner from the

fusing unit. After removing the oil bottle, be sure to remove the oil remaining in the
fusing unit with the supplied syringe. Failure to do so will cause severe damage to
the printer.

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xiv

CHAPTER 1

PRODUCT OUTLINE

HL-3450CN SERVICE MANUAL

CHAPTER 1 PRODUCT OUTLINE

1-2

CONTENTS

CHAPTER 1 PRODUCT OUTLINE .....................................................1-3

1. FEATURES..........................................................................................................1-3

2. PARTS NAMES & FUNCTIONS..........................................................................1-6

3. INTERNAL STRUCTURE....................................................................................1-8

4. DESCRIPTION OF CONTROL PANEL ...............................................................1-9

4.1 Video Controller Mode.................................................................................................................1-9

4.2 Engine Controller Mode...............................................................................................................1-9

1-3

CHAPTER 1 PRODUCT OUTLINE

1. FEATURES

This printer has the following features:

2400 x 600 dpi Class Resolution

The printer prints pages with a resolution of 600 dots per inch (dpi) as default. It also
provides higher quality printout which is the equivalent of 2400 x 600 dpi resolution when
using High Resolution Control (HRC) or Color Advanced Photoscale Technology (CAPT).

High Speed Color Laser Printing

The printer allows crisp printing in 24 bit brilliant color. The printer prints at a speed of 24
pages per minute in monochrome mode and 6 pages per minute in full color mode when
printing A4 or Letter size paper in Landscape orientation. The controller utilizes a high speed
32-bit RISC microprocessor and special hardware chips, which provides a very fast
processing speed.

HL-3450CN SERVICE MANUAL

High Resolution Control (HRC)

The high resolution control (HRC) technology provides clear and crisp printouts and improves
even the 600 dpi resolution. This mode is effective when printing text data.

Color Advanced Photoscale Technology (CAPT)

®

The printer can print graphics in 256 shades for each color in HP

color printer PCL5C™ and
BR-Script 3 emulations, producing nearly photographic quality. This mode is effective when
printing photographic images.

Maintenance-Free & Economical Tone r Cartridge

A toner cartridge can print up to 14,000 (Black) and 8,500 (Cyan, Magenta and Yellow)
single-sided pages at 5% coverage. The one piece, easy-to-replace toner cartridges do not
require difficult maintenance.

Universal Media Cassette

This printer loads paper automatically from the media cassette. Since the media cassette is
a universal type, a number of different sizes of paper can be used. Even envelopes can be
loaded from the media cassette.

Three Interfaces

This printer has a high speed, bi-directional parallel interface, USB and Ethernet
10/100BaseTX.

If your application software supports the bi-directional parallel interface, you can monitor the
printer status. It is fully compatible with the industry-standard bi-directional parallel interface.

The Brother network board (NC-4100h) is factory installed in the HL-3450CN, which enables
you to use this printer in the TCP/IP, IPS/SPX, Apple Talk, DLC/LLC, Banyan VINES, DEC
LAT and NetBEUI environments. Also, many useful utilities, such as BRAdmin Professional
for the administrator and Brother network printing software, are included in the CD-ROM
supplied with the HL-3450CN printer. For setup, see the Network User’s Guide.

CHAPTER 1 PRODUCT OUTLINE

1-4

Automatic Interface Selection

The printer can automatically select the bi-directional parallel, USB, or Ethernet 10/100 Base
TX depending on the interface port through which it receives data. With this feature, the
printer can be connected to more than one computer.

Five Emulation Modes

®

The printer can emulate Hewlett-Packard
mode), PostScript

®

3 language emulation (Brother BR-Script 3) printers, the industry-

standard HP-GL™ plotter as well as EPSON

Color PCL® 5C language (PCL6® in monochrome

®

FX-850™, and IBM® Proprinter XL® printers (in
monochrome mode). It is possible to print with all application programs that support one of
these printers.

Automatic Emulation Selection

The printer can automatically select the printer emulation mode depending on the print
commands it receives from the computer software. With this feature, many users can share
the printer on a network.

Data Compression Technology

The printer can internally compress the received graphics and font data in its memory so that
it can print larger graphics and more fonts without additional memory.

Various Fonts

The printer has 66 scalable and 12 bitmapped fonts. The fonts that can be used will vary
according to the selected emulation mode.

In PCL mode, you can also print the 13 kinds of bar codes listed below. In BR-Script mode,
the printer has 165 scalable fonts.

< Bar Code Printing >
This printer can print the following 13 types of bar codes:

x

Code 39

x

Code 128

x

Interleaved 2 of 5

x

Codabar

x

ISBN (EAN)

x

ISBN (UPC-E)

x

UPC-A

x

UPC-E

x

EAN-8

x

EAN-13

x

EAN-128

x

FIM (US-PostNet)

x

Post Net
(US-PostNet)

CCITT G3/G4

Since the printer supports the CCITT G3/G4 format in addition to HP-compatible formats, it
can quickly receive and print data compressed in this format.

Lock Panel

If the panel button settings have been changed, the printer may not work as expected. It is
possible for the administrator of the printer to lock the settings to prevent changes from being
made.

Power Save Mode

The printer has a power save mode. As laser printers consume power to keep the fixing
assembly at a high temperature, this feature can save electricity when the printer is on but
not being used. The factory setting of the Power Save mode is ON so that it complies with
the new EPA Energy Star new specification.

HL-3450CN SERVICE MANUAL

1-5

Toner Save Mode

The printer has an economical toner save mode. This mode allows you to reduce the printer
running cost substantially in addition to the improved life expectancy of the toner cartridge.

Reprint Function

A touch of a panel button allows reprinting of the last print job without sending the data again
from the computer. When there is not enough memory to print the last complete job out, the
last print page can be reprinted. Data can be stored in an IDE HDD that can be optionally
installed. It can be reprinted by selecting a document from the control panel or the browser.
When the private print driver is selected, Secure Printing can be executed which allows you
to print only when a password is entered.

Saving User Settings

It is possible to operate the printer differently from other users with the panel button settings.
One set of user settings can be stored.

*PANTONE

®

Calibrated

There are many variables in process reproduction of colors generated by the HL-3450CN,
any one of which may affect the quality of the PANTONE Color simulation, including;

x

Type of paper used

x

Type of toner used

x

Effective final resolution

x

Dot structure/halftones

For optimal results, it is recommended that the following materials and settings are used.

1) NEUSIEDLER color copy paper

2) Brother Toner Cartridges TN-02 BK/C/M/Y

3) 600 x 600 dpi resolution

CHAPTER 1 PRODUCT OUTLINE

1-6

1

3

M

6

8

7

2. PARTS NAMES & FUNCTIONS

<Front View>

5. Power button

. Upper cover

2. Control panel

4. Top cover
(Paper Exit Unit)

<Rear View>

. Front cover

edia cassette

Fig. 1-1

Paper exit unit

. Controller box

. Power inlet

. Rear access cover

Fig. 1-2

1-7

No. Part Name Outline of Functions

HL-3450CN SERVICE MANUAL

1 Upper cover

2 Control panel

3 Front cover

To act as an upper enclosure and also as a
paper tray for printed paper.

To display the status of printer operations and
control the printer directly.

To act as a front enclosure, opened when
replacing a toner cartridge or waste toner pack.

To exit the printed paper onto the upper cover,

Top cover (Paper exit

4

unit)

acting also as part of the paper tray for printed
paper. To be opened when replacing an OPC
belt cartridge or Drum cleaner.

5 Power button

To operate power-on and off to the printer.
(Push for On/Off operation)

6 Power inlet To connect a power supply cable.

7 Re ar access cover

8 Controller box

To act as a rear enclosure, opened when
clearing an internal jam or doing maintenance
work.

Space where the main (video controller) PCB is
installed.

CHAPTER 1 PRODUCT OUTLINE

1-8

2

1
(

1

3. INTERNAL STRUCTURE

<Cross Sectional View >

. OPC Belt Cartridge

4. Fusing Unit

3. Drum Cleaner

K

Y
M
C

7. Paper Discharger

8. Transfer Roller

5. Transfer Unit

6. Transfer Drum

10. Paper Pick-up
Roller

Fig. 1-3

No. Components Name Outline of Functions

. Toner Cartridge

K, Y, M, C)

1. Laser Unit

9. Media Cassette

1 Toner Cartridge

Contain the toner (K, Y, M, C) for developing.
Each toner cartridge (K, Y, M, C) is independent.

2 OPC Belt Cartridge Forms images and includes the OPC belt.

3 Drum Cleaner

Cleans and collects waste toner adhering to the transfer

drum.
4 Fusing Unit Fixes by heat and pressure the toner image onto the paper.
5 Transfer unit Transfers toner images from the transfer drum to the paper.

6 Transfer Drum

7 Paper Discharger

Forms color images, combining the toner images from the

OPC belt on the drum.

Emits a corona charge for separating the paper from the

transfer drum.
8 Transfer Roller Transfers the toner image on the transfer drum to the paper.
9 Media Cassette Feeds paper automatically.

10 Paper Pick-up Roller Feeds paper automatically from the media cassette.

11 Laser Unit

Generates a modulated laser beam and scans the OPC belt

to produce the image.

1-9

4. DESCRIPTION OF CONTROL PANEL

The printer control panel provides control of the printer including test printing, maintenance
operations performed by the video controller and also the ones which are performed by the
engine controller.

The Video Controller Mode and the Engine Controller Mode have some common functions.
Under normal circumstances the functions in the Video controller mode will be used. Refer to
CHAPTER 5 for further information.

4.1 Video Controller Mode

The printer goes into the Video Controller Mode when the power is turned on by pressing the
power button.

The Video Controller Mode supplies the general test printing and setting functions and some
of the maintenance operations. If further engine settings are required, use the Engine
Controller Mode.

HL-3450CN SERVICE MANUAL

4.2 Engine Controller Mode

The printer goes into the Engine Controller Mode when power is turned on by pressing the
power button at the same time as holding down the
(Refer to Fig.1-4.)

NOTE:
This mode provides unique control panel display and operation functions which are

completely different from the ones described on the actual control panel labels or in the
user’s guide. Refer to CHAPTER 5 for detailed information.

Secure print, Back

and

Set

buttons.

CHAPTER 1 PRODUCT OUTLINE

1

3

1

KCMY

2

Power DataReady

4

5

6

7

8

11

No. LED / Button Name

1 LCD: 16 character by 2 lines
2 Power LED
3 Ready LED
4 Data LED
5 Go button
6 Job Cancel button
7 Alarm LED
8 Secure Print button

9 - button
10 + button
11 Reprint button
12 Back button
13 Set button

Alarm

Secure

Print

Reprint

Go

Back

Fig. 1-4

Menu

Job

Cancel

Set

9

10

12

13

-10

CHAPTER 2

SPECIFICATIONS

HL-3450CN SERVICE MANUAL

CHAPTER 2 SPECIFICATIONS

2-2

CONTENTS

CHAPTER 2 SPECIFICATIONS..........................................................2-3

1. RATING ..............................................................................................................2-3

2. GENERAL SPECIFICATIONS............................................................................2-4

2.1 Printing .......................................................................................................................................2-4

2.2 Functions....................................................................................................................................2-4

2.3 Electrical and Mechanical...........................................................................................................2-5

2.4 Paper..........................................................................................................................................2-6

2.4.1 Printable media....................................................................................................................2-6

2.4.2 Media cassette capacity ......................................................................................................2-8

2.4.3 Printed output.......................................................................................................................2-8

2.5 Printing Area...............................................................................................................................2-8

2.5.1 Effective printable area........................................................................................................2-8

2.5.2 Print guarantee area..........................................................................................................2-10

3. ENVIRONMENTAL CONDITIONS.....................................................................2-11

3.1 Ambient Temperature / Humidity / Altitude...............................................................................2-11

CHAPTER 2 SPECIFICATIONS

1. RATING

HL-3450CN SERVICE MANUAL

WARNING

Use the power supply cable supplied with the printer, or a similar cable complying
with the following specification (3-wire power cable with ground).

Use of an “out of specification” cable may result in an electric shock.

Destination Voltage (V) Frequency (Hz) Input Current (A) Power Cord (Piece)

US / Canada 120 50/60 11 1

Europe 220 - 240 50/60 6 1 *

* For European models, the power supply cable depends on the country as follows;

Figure Rating Approval Agency Applicable Area

A

B

Figure A: For Europe (Sample)

250VAC, 6A

VDE, DEMKO, SEV Europe (Continent)

BS UK

2.5m

Figure B: For UK

2.5m

NOTE:
For details of other power supply cables, refer to the parts reference list.

** For rating labels, refer to ‘Safety Instruction’ on Page viii.

2-3

CHAPTER 2 SPECIFICATIONS

2. GENERAL SPECIFICATIONS

2.1. Printing

Print method Electro photography by semiconductor laser beam scanning
Laser Wavelength: 780nm

Output: 5mW max.
Resolution 600 x 600 dots per inch (Fine)

2400 x 600 dots per inch (using HRC and CAPT)

Print speed Monochrome mode: 24 page/minute
Full color mode: 6 page/minute
(when printing A4/Letter-size paper in Landscape orientation)

Monochrome mode: 12 page/minute
Full color mode: 3 page/minute
(when printing A3/Ledger-size paper in Portrait orientation)

Warm-up Max. 210 seconds at 20°C (68°F)
First print Monochrome mode: 19 seconds or less

Full color mode: 34 seconds or less
(when loading A4/Letter-size plain paper in Landscape orientation by

Print media Toner in a single-color single-component cartridge.
Life Expectancy: 14,000 single-sided pages/cartridge (Black)
8,500 single-sided pages/cartridge (C/M/Y)
(when printing on A4/Letter-size paper with 5% coverage)

Resident printer fonts <HP PCL, EPSON FX-850, and IBM Proprinter XL modes>
66 scalable fonts and 12 bitmapped fonts,11 bar codes
<BR-Script 3 mode>
165 scalable fonts

(The resolution can be enhanced to 2400dpi class by using Brother
exclusive HRC (High Resolution Control) and CAPT (Color Advanced
Photoscale Technology).)

face down print delivery from standard upper cassette feed)

2.2. Functions

CPU Toshiba TMPR4955-266 (TX4955-266MHz)
Emulation Automatic emulation selection

Interface Automatic interface selection among the bi-directional parallel,

RAM 64 Mbytes
(Expandable up to 384Mbytes with DIMMs)
The standard memory fitted can vary depending on the printer model

HDD option 2.5 inch IDE HDD
Compact Flash 1 card slot: Compact Flash Type II
Control panel 8 buttons, 4 LEDs and a 16-column x 2 lines liquid crystal display
Diagnostics Self-diagnostic program

x

HP Color Printer (PCL5C) including HP LaserJet 4+ (PCL5e) and
HP LaserJet 5 (PCL6 monochrome)

x

BR-Script 3 (Adobe PostScript 3 compatible)

x

HP-GL

x

EPSON FX-850

x

IBM Proprinter XL

Universal Serial Bus (USB) and Ethernet 10/100 Base TX.

and country.

2-4

2-5

2.3. Electrical and Mechanical

Power source U.S.A. and Canada: AC 120V, 50/60Hz
Europe and Australia: AC 220 to 240V, 50/60Hz

Power consumption Printing (peak*): 1350W or less
Printing (average): 600W or less
Standing by (peak*): 1350W or less
Standing by (average): 200W or less
Sleep: 30W or less

Noise: Printing: 55dB A or less
Standing by: 48dB A or less

Temperature: Operating: 10 to 32.5°C (50 to 90.5°F)
Non operating: 5 to 35°C (41 to 95°F)
Storage: 0 to 35°C (38 to 95°F)

Humidity: Operating: 20 to 80% (non condensation)
Storage: 10 to 90% (non condensation)

HL-3450CN SERVICE MANUAL

Dimensions: 615 x 540 x 420 mm (24.2 x 21.3 x 16.5 inches)
(W x D x H) 615 x 620 x 610 mm (24.2 x 24.4 x 24.0 inches)
with the Duplex Unit and one optional lower tray unit fitted
615 x 620 x 750 mm (24.2 x 24.4 x 30.6 inches)
with the Duplex Unit and two optional lower tray units fitted

Weight: Approx. 46kg (101lbs.)
Approx. 54kg (119lbs.) including consumables*

*Consumables are defined as:
Belt cartridge, Toner cartridge (Y, M, C, K), Fuser oil bottle,
Fuser cleaning roller, Waste toner Pack

Optional Units:

x

Lower Tray Unit: Approx. 11kg (24lbs.)

x

Duplex Unit: Approx. 12kg (26lbs.)

x

Standard Media Cassette: Approx. 2.1kg (4.6lbs.)

x

Lower Tray Unit Media Cassette: Approx. 2.7kg (6.0lbs.)

*NOTE:

x

The peak figure of power consumption is worked out when the halogen heater lamp is
turned ON.

x

The peak figure of power consumption is worked out excluding inrush current value.

x

The peak figure of power consumption is a reference value and should be used internally
at Brother offices only.

x

The power consumption figure quoted for sleep mode is when the fan has stopped.

CHAPTER 2 SPECIFICATIONS

2.4. Paper

The standard media cassette (upper cassette) is supplied with the printer. The optional lower
tray unit and the optional A4/Letter cassette can also be installed.

NOTE:
The standard upper cassettes and the optional A4/Letter cassette are interchangeable

between the upper and the lower feeder.

2.4.1 Printable media

(1) Type & size

Paper source Paper type Paper Size

Standard upper cassette

Plain paper A3, B4, A4, Ledger, Executive, Legal,

Letter, B5 (ISO/JIS), 330x483mm

(13”x19”)
Envelope COM10, DL,
Transparency A4, Letter
Label A4, Letter
Other size width 210-330mm (8.2”-12.9”)

length 176-483mm (6.9”-18.8”)
Optional lower cassette Plain paper A3, B4, A4, B5 (ISO/JIS), Legal, Ledger,

Letter
Optional A4/Letter cassette Plain paper A4, Letter, B5 (ISO/JIS), Executive
Envelope: COM10, DL
Transparency A4, Letter
Label A4, Letter
Other size: width 210-297mm (8.2”-11.7”)

length 176-297mm (6.9”-11.7”)

(2) Paper weight specifications

Paper cassette Optional lower tray Optional duplex unit
Normal paper

60 to 90 g/m

2

m

m

(16 to 24 lbs)

Thick stock

90 to 160 g/m

(24 to 43 lbs)

2

90 to 105 g/m

(24 to 28 lbs)

2-6

2

2-7

(3) Recommended paper specifications

!

Item Description
Basis Weight (g/m2) 82 ± 5
Thickness (µ m) 95 ± 6
Smoothness (Bekk) (seconds) 90 ± 20
Stiffness (Clark) 100 ± 15
Brightness (%) 85 ± 2

10

10

Surface Resistance (:)
Grain Direction Long

Measurement Condition: 17.5 ~ 27.0°C, 50 ~ 70%RH

~ 1011

HL-3450CN SERVICE MANUAL

CAUTION:

When you are choosing print media, be sure to it is designed for use with a laser printer and
load the media cassette correctly. Also follow the information given below to prevent any
paper jams, print quality problems or printer damage;

<Paper type to avoid>

x

Highly textured paper.

x

Smooth or shiny paper.

x

Paper that is coated or has a chemical finish.

x

Damaged, wrinkled or pre-folded paper.

x

Paper exceeding the recommend weight specification in the manual.

x

Paper with tabs and staples.

x

Letterheads using low temperature dyes or thermography.

x

Multipart or carbonless paper.

<Envelopes type to avoid>

x

Envelopes constructed with a paper with a weight that exceeds the paper weight
specifications for the printer.

x

Poorly manufactured envelopes with edges that are not straight or consistently square.

x

Envelopes with ‘baggy’ construction of folds that are not sharply creased.

x

Envelopes with transparent windows, holes, cutouts or perforations.

x

Envelopes with clasps, snaps or tie strings.

x

Envelopes made with smooth or shiny paper.

x

Envelopes that are rough, highly textured, or deeply embossed.

x

Envelopes that do not lie flat or that are curled, wrinkled, or irregularly shaped.

x

Envelopes having an open flap with an adhesive that seals the envelope.

<Transparencies / labels type to avoid>

x

Transparencies / labels that cannot withstand a temperature of 200 degrees centigrade
(392 degrees Fahrenheit) for a period of 0.1 seconds.

NOTE:
Keep the paper sealed in the bag as supplied and do not open the bag until the paper is

required for use.

CHAPTER 2 SPECIFICATIONS

2.4.2 Media cassette capacity

Maximum load height: 27mm (1.06 inches)

x

Plain paper: 250 sheets of 75g/m

x

Envelopes : 15 sheets

x

Transparency: 50 sheets

x

Label: 80 sheets

2.4.3 Printed output

(1) Capacity
250 sheets of 75g/m
(2) Delivery
Face-down print delivery

Note: Face down: Delivers the printed side of the paper downwards.

2

(20lb) paper for the standard/optional A4/Letter

cassette
500 sheets of 75g/m

2

(20lb) paper (plain paper stacked in the output tray)

2

(20lb) for the optional lower cassette

2.5 Printing Area

2.5.1 Effective printable area

The effective printing area means the area within which the printing of all the data received
without any omissions can be guaranteed. (Refer to Table 2-1 for details.)

F

E

B

D

A

CE

F

Fig. 2-1

2-8

HL-3450CN SERVICE MANUAL

2-9

Table 2-1: Effective Printing Areas

Size A B C D E F

A 4

Letter

Legal

B 5 (JIS)

B 5 (ISO)

Executive

COM-10

D L

13x19 330mm

A 3 297mm

B 4 257mm

Ledger 279.4mm

210.0mm

8.27”
(2,480 dots)

215.9mm

8.5”
(2,550 dots)

215.9mm

8.5”
(2,550 dots)

182.0mm

7.16”
(2,149 dots)

176.0mm

6.93”
(2,078 dots)

184.2mm

7.25”
(2,175 dots)

104.8mm

4.125”
(1,237 dots)

110.1mm

4.33”
(1,299 dots)

13”
(3,900 dots)

11.7”
(3,507 dots)

10.1”
(3,035 dots)

8.5”
(3,300 dots)

297.0mm

11.69”
(3,507 dots)

279.4mm

11.0”
(3,300 dots)

355.6mm

14.0”
(4,200 dots)

257.0mm

10.12”
(3,035 dots)

250.0mm

9.84”
(2,952 dots)

266.7mm

10.5”
(3,150 dots)

241.3mm

9.5”
(2,850 dots)
221mm

8.66”
(2,598 dots)

482.6mm
19”
(5,700 dots)
420mm

16.5”
(4,960 dots)
364mm

14.3”
(4,298 dots)
432mm
14”
(5,100 dots)

203.2mm

8.0”
(2,400 dots)

207.44mm

8.16”
(2,450 dots)

207.44mm

8.16”
(2,450 dots)

173.54mm

6.82”
(2,049 dots)

167.54mm

6.59”
(1,978 dots)

175.74mm

6.91”
(2,075 dots)

96.34mm

3.785”
(1,137 dots)

101.64mm

3.99”
(1,199 dots)

306.5mm

12.1”
(3,620 dots)

288.5mm

11.4”
(3,407 dots)

248.9mm

9.8”
(2,935 dots)

270.9mm

10.7”
(3,200 dots)

288.5mm

11.36”
(3,407 dots)

271.0mm

10.67”
(3,200 dots)

347.1mm

13.67”
(4,100 dots)

248.5mm

9.78”
(2,935 dots)

241.5mm

9.5”
(2,852 dots)

258.3mm

10.17”
(3,050 dots)

232.8mm

9.16”
(2,750 dots)

211.5mm

8.33”
(2,498 dots)

475.8mm

18.7”
(5,620 dots)

411.5mm

16.2”
(4,860 dots)

355.4mm
14”
(4,198 dots)

423.3mm

16.7”
(5,000 dots)

3.4mm

0.13”
(40 dots)

4.23mm

0.17”
(50 dots)

Ç

Ç

Ç

Ç

Ç

Ç

11.85mm

0.47”
(140 dots)

4.23mm

0.17”
(50 dots)

Ç

Ç

4.23mm

0.17”
(50 dots)

Ç

Ç

Ç

Ç

Ç

Ç

Ç

Ç

Ç

Ç

Ç

NOTE:

x

The paper sizes indicated here should conform to the nominal dimensions specified by
JIS.

x

A4 paper must accommodate 80 characters printed in pica pitch (203.2 mm).

x

The dot size is based on 300 dpi resolution.

x

Organizer is not supported by any printer emulation (command).

CHAPTER 2 SPECIFICATIONS

P
O

P
O

3

5

N
a

N
a

N
a

4

4

#
D

2.5.2 Print guarantee area

<Plain paper>

3mm

5mm

Print

guarantee

area

Fig. 2-2

mm

on printable

rea

on guarantee

rea

mm

mm

mm

aper: 5mm
ther: 10mm

aper: 4mm

ther: 10mm

<Envelope>

42mm

16mm

3mm

4mm

Non guarantee
area

#10: 68mm
DL: 40mm

on printable

rea

Print guarantee

area

4mm

10: 68mm

L: 40mm

Fig. 2-3

2-10

2

3. ENVIRONMENTAL CONDITIONS

R
1
5

3.1 Ambient Temperature / Humidity / Altitude

(1) Under Operational conditions: 10.0 a 32.5qC (50 ~ 90.5qF), 20 a 80%RH (See the
figure below)

80
70

HL-3450CN SERVICE MANUAL

60

50

ecommended Condition;

27.0qC

a

7.5
0 a 70%RH

40

20

Ambient Humidity (%RH)

100 17.5 20 27 30 32.5 40

Ambient Temperature ( )

C

(2) Under Non Operational conditions: 5.0 a 35.0qC (41 ~ 95qF), 10 a 80%RH (See the

figure below.)

80

60

40
30

Ambient Humidity (%RH)

20
10

5

10020303540

Ambient Temperature( )

C

-11

CHAPTER 2 SPECIFICATIONS

(3) Storage and transportation environment of printer
The following defines the storage and transportation environment of printers that have been

packed according to Brother specification. However, this section does not cover the OPC
belt cartridge, toner cartridges and developer cartridges.

In particular, since consumables such as the toner cartridges and OPC belt are individually
packaged, the following environmental conditions should be respected. During
transportation, strictly refrain from leaving the goods on the ground or under the sun.

Temperature

Humidity

Normal
Conditions

Severe
Conditions

0qC a 35qC (32qF a 95qF)

High Temperature: 35qC a 40qC (95qF a 104qF)
Low Temperature: -10qC a 0qC (14qF a 32qF)

10% a 90%RH
Period of Storage One Year
Other No condensation
Atmosphere

613 a 1,067hpa (460 a 800mmHg)

The period under the severe conditions should not be continuous, and is assumed as an
accumulation of intermittent time. However, an individual period of intermittent time under
severe conditions should not be allowed to exceed 48 hours.

NOTE:
Normal conditions should occupy more than 90% of total storage period.
Severe conditions should be less than 10% of total storage period.

2-12

CHAPTER 3

INSTALLATION

CHAPTER 3 INSTALLATION

3-2

CONTENTS

CHAPTER 3 INSTALLATION .........................................................3-3

1. CONDITIONS REQUIRED FOR INSTALLATION...........................................3-3

1.1. Environmental Conditions.....................................................................................................3-3

1.2. Basic Layout of Printer Set-up Location ...............................................................................3-3

2. UNPACKING...................................................................................................3-5

2.1 Unpacking of Printer..............................................................................................................3-5

2.2 Unpack the Starter Kit ...........................................................................................................3-7

3. INSTALLATION WORK ..................................................................................3-8

3.1 Install the Oil Bottle and Fuser Cleaner.................................................................................3-8

3.2 Install the OPC Belt Cartridge ...............................................................................................3-9

3.3 Install the Toner Cartridge into the Printer...........................................................................3-11

3.4 Install the Media Cassette and Adaptor...............................................................................3-12

3.4.1 Install the media cassette .............................................................................................3-12

3.4.2 Install the envelope adaptor..........................................................................................3-13

3.5 Test Print.............................................................................................................................3-14



3-3

CHAPTER 3 INSTALLATION

1. CONDITIONS REQUIRED FOR INSTALLATION

Any Laser beam printer is likely to be influenced by the environment of the set-up location. If
the printer is set-up in an inappropriate location, the printer may not perform as expected.
Therefore, the following factors should be taken into consideration before deciding where to
set-up the printer.

1.1. Environmental Conditions

The printer should not be set up in the locations referred to in the following items (1) through
(8) which specify inappropriate locations for set-up.

(1) Where it is likely to receive direct sunlight or similar light. (For example, next to a

window)

(2) Where it is likely to suffer a big difference in temperature and humidity between the

maximum and minimum levels. (Normal operation environment is within 10qC a 32.5qC,
20 a 80%RH and without any condensation.)

HL-3450CN SERVICE MANUAL

(3) Where it is likely to be in a draft of cold air from an air-conditioner or warm air from a

heater, or to receive direct radiant heat.

(4) Where it is likely to be excessively dusty or be subject to corrosive gases such as

ammonia.
(5) Where it is likely that an ultrasonic humidifier will be used.
(6) Where it is likely to have poor ventilation.
(7) Where it is likely to have unstable conditions such as when the set-up table is not strong

enough.
(8) Where it is likely to be tilted (angle from the horizontal should not be greater than r1q).

1.2. Basic Layout of Printer Set-up Location

CAUTION

In the case when the printer is set on a table, confirm that the media cassette does not to
protrude out beyond the edge of the table.

x

Any protrusion of the media cassette may catch a passersby and result in damage to the
printer.

x

Protrusion of the media cassette may cause the printer to tilt or fall over if the operator
leans against or applies excessive force to the media cassette, which may cause injuries.

CHAPTER 3 INSTALLATION

3-4

Fig.3-1 shows the basic layout of the printer set-up location that is suitable for smooth
operation and maintenance of the printer.

Table

20cm (8")

Paper Exit Side

80cm (32")

50cm (20")

20cm (8")

16cm
(6.4")

70cm
(28")

70cm
(28")

Front Side

10cm (4")

Fig. 3-1

x

A space in front of the printer of 70cm is necessary to open the front cover.

x

A space at back of the printer of 20cm is necessary to open / close the rear access cover.

x

The space on both sides of the printer of 10cm is necessary for general access.

3-5

2. UNPACKING

The package containing a printer weighs approximately 66kg (145lbs), so it is too heavy

x

for one person to carry. It needs two adults or more to move the printer. Since the printer
is a precision machine, make sure that it is carried slowly with care so that no impact
occurs to the printer while moving it.
Do not attempt to lift a printer when it is covered by the polyethylene bag because it is

x

slippery and may result in damage and injury if dropped.

2.1 Unpacking the Printer

Refer to Fig.3-2 on the next page.

1) Cut the two bands from around the packing carton.

2) Remove the binding tape from the top of the package.

3) Open the top of the package and take the ST packing set out.

HL-3450CN SERVICE MANUAL

WARNING

4) Remove the upper packing (4 locations).

5) Take the customisation kit** out of the box.

6) Take the power cable out of the box. (for US / Canada only).

7) Open up the polyethylene bag enclosing the printer and remove it.

8) Remove the silica gel.

9) Lift up and set up the printer in a suitable location using at least two persons.

** For USA/Canada, the kit contains the use’s guide and printer driver disks.

For other countries, the kit contains the use’s guide, printer driver disks and the
powercable.

CHAPTER 3 INSTALLATION

3-6

STARTER KIT
(ST PACKING SET 3 (B))

STARTER PACKING
SLEEVE

STARTER KIT PACKING (U)

Media cassette

OUTER BOX

Toner cartridges

STARTER KIT PACKING (M)

OPC belt cartridge

Oil bottle

L-SHAPED
PAPER SUPPORT

Toner cartridges

Fuser cleaner

L-SHAPED

PAPER SUPPORT

BASE SET 3 (B)

SILICA GEL

Power cable

POLYETHYLENE
BAG (EN)

PALLET 3 (B)

STARTER KIT
PACKING (L)

BAND

SHIPPING TAPE

TAPE

PROTECTIVE
PACKING

Fig. 3-2

HL-3450CN SERVICE MANUAL

3-7

Y
M
C
K

2.2 Unpack the Starter Kit

<Unpacking Procedure>

1) Open the vinyl bag and slide off the cardboard sleeve covering the starter kit.

2) Confirm all of the following parts are inside the starter kit packing box.

No. Kit Name Appearance Quantity

Toner Cartridge (Y, M,

1

C, K)

(Yellow)

(Magenta)
(Cyan)
(Black)

4

2 OPC Belt Cartridge 1

3 Oil Bottle 1

4 Fuser Cleaner & Syringe 1

Media Cassette with

5

Envelope Adapter

PRECAUTION

When shipping the printer, remove the oil bottle and the fuser cleaner from the fusing unit.
After removing the oil bottle, be sure to remove the oil remaining in the fusing unit with the
supplied syringe. Failure to do so will cause severe damage to the printer.

1

CHAPTER 3 INSTALLATION

3-8

3. INSTALLATION WORK

Do not lean against or apply any excessive force to the media cassette or open covers;
otherwise it may cause the product to tilt or fall over and result in injuries.

Install the parts of the starter kit into the printer according to the following procedures:

3.1 Install the Oil Bottle and Fuser Cleaner

(1) Release the two sets of retainer lock

levers for both the oil bottle and the
fuser cleaner.

(2) Set the fusing unit pressure release

levers to the SET position.

CAUTION

Pressure release

lever

(3) Install the oil bottle into the fusing unit.

NOTE:
When installing the oil bottle, be sure not to

touch the oil feed connection at the bottom
of the bottle to avoid oil leakage.

(4) Install the fuser cleaner into the fusing

unit.

(5) Secure the oil bottle and the fuser

cleaner with the retainer lock levers.

(6) Close the top cover.

Oil bottle

Fuser cleaner

Fig. 3-3

Fig. 3-4

Pressure release
lever

Fig. 3-5

HL-3450CN SERVICE MANUAL

3-9

NOTE:
The retainer lock levers for the fuser cleaner and oil bottle are located as shown in the figure

below;

Retainer lock levers

Fuser cleaner

Oil bottle

3.2 Install the OPC Belt Cartridge

x

Do not directly touch the OPC belt surface with bare
hands or gloves.

x

If the belt is exposed for more than two minutes to a light
source of 800 lux, the belt may be damaged.

(1) Open the front cover and the top cover

by releasing the latches.

Retainer lock levers

Fig. 3-6

PRECAUTION

Top cover

PRECAUTION

When installing or removing the OPC
belt, be sure to open the front cover first.
Failure to do so will cause the OPC belt
to be damaged due to contact with the
toner cartridges.

Front cover

Fig. 3-7

CHAPTER 3 INSTALLATION

3

O

P

T
r

(2) Release the belt cartridge lock levers

(left & right).

(3) Pull and remove the tension release

pins on both sides (left & right) of the
OPC belt cartridge.

(4) Remove the protective sheet from the

OPC belt cartridge.

Belt cartridge

lock lever (L)

ension

elease pin

OPC belt

cartridge

Fig. 3-8

Belt cartridge lock
lever (R)

(5) Install the OPC belt cartridge into the

guides at both sides in the printer.

(6) Set the belt cartridge lock lever at both

sides (left and right).

rotective sheet

Fig. 3-9

PC belt cartridge

Fig. 3-10

Tension
release pin

-10

3

3.3 Install the Toner Cartridges into t he Pri nt er

HL-3450CN SERVICE MANUAL

(1) Rock each of the cartridge 3 to 4 times

through 30

o

to the horizontal.

(2) Pull off the tape labeled ‘REMOVE’ from

the toner cartridge.

(3) Remove the protective cover from the

toner cartridge.

o

30

Protective label

Fig. 3-11

Fig. 3-12

o

30

Protective
cover

(4) Install the four toner cartridges by

sliding them gently along the guides into
the printer. DO NOT USE FORCE TO
INSERT THE CARTRIDGES AND DO
NOT PUSH THEM FULLY INTO THE
PRINTER, THEY WILL BE
POSITIONED CORRECTLY WHEN
THE FRONT COVER IS CLOSED.

NOTE:
The installation order of the four toner

cartridges should be from the bottom to the
top, in terms of colors this is in the order
Cyan (C), Magenta (M), Yellow (Y), and
Black (K).

(3) Close the front cover.

?

Fig. 3-13

Fig. 3-14

@

K

Y
M
C

Fig. 3-15

-11

CHAPTER 3 INSTALLATION

3

C

P

3.4 Install the Medi a Casset t e and Adapt er

3.4.1 Install the media cassette

(1) Remove the cassette cover from the

media cassette.

(2) Set the paper guide according to the

print paper size.
i) Horizontal direction; Holding the

green side plate to meet the paper
size position.

ii) Vertical direction; Holding the green

color lever, adjust the end plate to
meet the paper size position.

assette cover

Fig. 3-16

Paper guide

aper guide

(3) Load the paper into the cassette.

PRECAUTION

Loading capacity of the cassette is
subject to the type of media in use.
Keep the loading level below the upper
limit marked on the label. Excessive
loading of media over the upper limit will
result in paper feed jams or print quality
problems.

(4) Install the cassette cover.
(5) Install the cassette into the printer.

Fig. 3-17

PAPER
LABEL

OHP FILM

Fig. 3-18

-12

3

3.4.2 Install the envelope adapter

P

C

H

NOTE:
The specification of envelopes feedable from the envelope adapter are as follows;

Capacity: 15 envelopes

x

Size: DL (110 x 220 mm), #10 (105 x 241 mm)

x

HL-3450CN SERVICE MANUAL

(1) Prepare the media cassette and

envelope adapter.

(2) Put the adapter on the cassette base

and engage the hooks provided on the
leading edge of the adapter (left and
right) into the cassette base.

(3) Move the envelope guide to meet the

adapter base.

(4) Move the paper guides to meet the

desired envelope size.

(5) Load the envelopes into the adapter.

Envelope adapter

Envelope guide

Paper guide

Cassette base

Fig. 3-19

Adaptor base

Fig. 3-20

aper guide

PRECAUTION

Do not load media in the adapter higher
than the specified capacity limit,
otherwise it may result in paper feed
jams or print quality problems.

Fig. 3-21

CAUTION

When removing the envelope adapter from the media cassette, pull the adapter toward you
while holding the trailing edge of the adapter up approximately 10mm.
Do not hold up the trailing edge of the adapter by force, otherwise it may result in damage to
the hooks provided at the leading edge of the adapter.

Envelope adaptor

Cassette base

ook

Fig. 3-22

assette base

-13

CHAPTER 3 INSTALLATION

3

F

3.5 Test Print

(1) Make sure the printer power button is off. Do not connect the interface cable.

(2) Connect the AC power cord to the printer, and then plug it into the AC outlet.

ig. 3-23

Fig. 3-24

(3) Turn on the power button.

Fig. 3-25

-14

3

(4) After the printer warms, the READY message will appear.

KCMY

NETWORK READY

HL-3450CN

DataReadyPo wer

HL-3450CN SERVICE MANUAL

Alarm

Secure
Print

Reprint Back Set

Job

Go

Cancel

Fig. 3-26

(5) Press the Go button. The printer will print a test page. Check that the test page is

printed correctly.

KCMY

NETWORK READY

HL-3450CN

DataReadyPow er

Alarm

Job

Go

Cancel

Back Set

Fig. 3-27

-15

HL-3450CN SERVICE MANUAL

CHAPTER 4

STRUCTURE OF

SYSTEM

COMPONENTS

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4-2

CONTENTS

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS..................4-3

1. BASIC STRUCTURE.......................................................................................4-3

1.1 Mechanical Structures ............................................................................................................4-3

1.2 Basic Mechanism of Color Printing.........................................................................................4-5

1.2.1 Principle of color printing..................................................................................................4-5

1.2.2 Basic color printing process .............................................................................................4-5

1.3 Structure of the OPC Belt .......................................................................................................4-7

1.4 Print System and Transfer System.........................................................................................4-8

1.4.1 Structure of the printer......................................................................................................4-9

1.4.2 Basic structure of the printing system............................................................................4-10

1.4.3 Details of each process..................................................................................................4-12

1.5 Scanning System..................................................................................................................4-23

1.6 Paper Transportation System...............................................................................................4-25

1.6.1 Outline............................................................................................................................4-25

1.6.2 Structure of paper transportation system.......................................................................4-25

1.7 Fusing Unit............................................................................................................................4-26

1.7.1 Structure.........................................................................................................................4-26

1.7.2 Fusing process...............................................................................................................4-27

2. STRUCTURE OF THE CONTROL SYSTEM.................................................4-28

2.1 Basic Structure - Electrical System and Functions...............................................................4-28

2.2 Control System - Control of the Print Process......................................................................4-37

2.3 Main PCB (Video Controller PCB)........................................................................................4-46

2.3.1 Outline............................................................................................................................4-46

2.3.2 Circuit.............................................................................................................................4-48

2.4 Low-voltage Power Supply Unit............................................................................................4-60

2.5 High-voltage Power Supply Unit...........................................................................................4-63

2.6 Connection Diagram.............................................................................................................4-65

HL-3450CN SERVICE MANUAL

4

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

1. BASIC STRUCTURE

1.1 Mechanical Structures

This laser beam color printer (hereinafter called “Printer”) consists of five mechanical
systems; Print, Transfer, Scanning, Paper Transport and Control System. The printer
produces color printing through the interactive operations of these five systems as shown in
Fig.4-1.

(1) Print System

The print system consists of the following 6 (six) functional parts located around the
OPC belt which form a toner image on the OPC Belt.

x

Charger Part

x

Exposure Part

x

Development Part

x

First Transfer Part

x

Discharger Part

x

Cleaner Part

(2) Scanning System

The scanning system consists of the following 2 (two) functional parts which form an
electrostatic latent image on the OPC Belt by scanning it with a laser beam.

x

Scanner Unit

x

Scanner Motor (SCM)

(3) Transfer System

The transfer system consists of the following 3 (three) functional parts and transfers
the toner image formed on the transfer drum onto the page.

x

Transfer Drum

x

Second Transfer Part

x

Drum Cleaner Unit

(4) Paper Transport System

The paper transport system consists of the following 5 (five) functional parts and picks
up paper from the media cassette, separates the paper from the transfer drum and
exits it from the printer body after fusing the toner image on the paper.

x

Media Cassette

x

Transport rollers

x

Paper Discharger

x

Fusing unit

x

Paper Exit

-3

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4-4

Main Motor

MM

Paper Exit Unit

Fusing Unit

Transfer Unit

AC Discharger Unit

Transfer Roller

Resistration Roller

Transport Roller

Paper Exit

Fix

Paper Discharger

Second Transfer

Drum Cleaner Unit

Drum Cleaning
Operation

Transfer Drum

First Transfer

Discharge

OPC Belt

Charge

Developer Motor

Development

Exposure

DM

Toner
Cartridge

K

Y

M

C

Scanner Unit

LD

Laser Diode

I/F Controller

MCTL

I/F Control

Sequence Control

Laser Control

SCM

Scaner Moter

Erase Lamp

Cleaning

DC Charger

Paper Feed

Paper Cassette

Fig. 4-1

4

(5) Control System

The control system consists of the following 4 (four) control parts and runs the printer
by processing the interface signals transmitted from the Host computer and interfacing
to the print, transfer, scanning and transport systems.

x

Sequence Control

x

Laser Control

x

Fusing Temperature Control

x

Interface Control

1.2 Basic Mechanism of Color Printi ng

1.2.1 Principle of color printing

Color printing is made through the subtractive process by combining the three primary colors,
yellow, magenta, and cyan. Fig.4-2 shows the three primary colors and subtractive process:

HL-3450CN SERVICE MANUAL

C

B

K

M

1.2.2 Basic color printing process

(a) The printer has a toner cartridge of each color yellow, magenta, cyan and black as

shown in Fig.4-3.

(b) The toner image developed using the primary colors is transferred to the transfer drum

for the printed color combination as shown in Fig.4-4 a .

(c) The toner image formed on the transfer drum is transferred to the transported paper as

shown in Fig.4-4 b .

R

G

Y

Fig. 4-2

Y: Yellow
M: Magenta
C: Cyan
R: Red
G: Green
B: Blue
K: Black

(d) The toner on the paper is fused by the thermal fixing unit to fix the toner image onto

the paper as shown in Fig.4-4 c .

Summarizing the above processes, a toner color layer is formed on the transported paper,
and subsequently, the color image is made through the subtractive process.

-5

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4-6

T

T

ransfer crum

OPC belt

oner cartridge

K

Y
M
C

Fig. 4-3

Toner

C

C

YYY

C

a

First Transfer

a

M

M

YYY

M

C

C

Transfer Drum

Y

Y

CCC

Y

Second Transfer

b

b

M

Y

Y

Y

M

M

CC

Paper

C

Fusing

Red

C

Cyan

R

Green

C

G

Paper

Fig. 4-4

4

1.3 Structure of the OPC Belt

T

P

A

I

S

The OPC belt consists of a surface layer having a photoconductor (OPC) of organic material,
the inner layer of an insulator material (PET) and an aluminum deposit layer in between. The
OPC belt is located as shown in Fig.4-5 as the main part of the print system.

OPC belt

Transfer drum

OPC belt cartridge

HL-3450CN SERVICE MANUAL

oner cartridge

Fig. 4-5

canner Unit

Electrode

hotoconductor (OPC)

luminum deposit layer

nsulator material

Fig. 4-6

-7

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4-8

1.4 Print System and Transfer System

Fig.4-7 shows the basic structure of the print system having the OPC belt as the main part
and the transfer system having the transfer drum. Color printing is achieved by actuating in
sequence each process in the print system and transfer system.

Print System

Transfer System

1

2

3

4

7

8

10

Chargimg

Exposing

Developing

OPC Belt

Transfer Drum(First Transfer)

Transfer Drum

Second Transfer(Paper)

Paper Dischanging

Fusing

KCMY

KCMY

KCMY

KCMY

OPC Belt Cleaning

6

5

9

Belt Discharge

Transfer Drum Cleaning

Transport System

11

Paper Exit

Fig. 4-7

4

1.4.1 Structure of the printer

4

3
2

M

1

No. Component Part Process

1 Charger Charging
2 Scanner Unit Exposing
3 Toner cartridge Developing
4 OPC belt cartridge Receives the Image
5 Transfer drum Transfers the Image
6 Erase lamp Discharges the Belt
7 Cleaning blade Cleaning the Belt
8 Transfer roller Transferring

9 Paper discharger Discharges the Paper
10 Drum cleaner Cleans the Drum
11 Fusing unit Fusing
12 Paper exit unit Exits the Paper

HL-3450CN SERVICE MANUAL

. OPC belt cartridge

12. Paper exit unit

11. Fusing unit

9. Paper discharger

8. Transfer roller

Transfer

5. Transfer drum

unit

Paper pick-up roller

10. Drum cleaner

6. Erase lamp

7. Cleaning
blade

Fig. 4-8

. Charger

edia cassette

. Toner cartridge

(K, Y, M, C)

. Scanner Unit

-9

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4

1.4.2 Basic structure of the printing system

A toner image is formed through the potential of the OPC belt varying in each of the charger,
exposure, development, transfer and cleaning processes.

(1) Process of Print System (See Fig.4-9.)

i) The OPC belt is biased to the voltage -CBV (V) by the power supply CBV.
ii) A negative high voltage is applied to the charger unit by the power supply CHV, and

a corona is generated as the result.

iii) The developer roller of the toner cartridges is biased to -DBV (V) by the power

supply DBV.

iv) The frame potential of the transfer drum is GND.

Fusing Unit

Cleaning Unit

FCBV

Toner

OPC Belt

Toner Cartridge

Paper Discharger

ACHV

Transfer Roller

THV (+)

THV ( - )

Transfer Drum

Paper

Erase Lamp

Fig. 4-9

Cleaning

Brade

K

Y

M

C

Charger

CHV

ZDV

Develop

DBV

CBV

Scanner Unit

Po

-10

4

(2) Variation of OPC Belt Potential (See Fig.4-10.)

i) The OPC belt is initially biased to -CBV (V).

HL-3450CN SERVICE MANUAL

ii) The OPC belt surface is evenly charged to V

(V) in the charging process.

0

iii) The potential of the exposure part of the OPC belt is reduced to -VR (V) as it is

exposed to the laser beam in the process of exposing, and an electrostatic latent
image is formed on the OPC belt as the result.

iv) Negatively charged toner is moved onto the exposed part of the OPC belt in the

development process due to the difference of potential between -VR (V) and -DBV
(V), and a visible toner image is formed as the result.

v) Negatively charged toner on the OPC belt moves to the transfer drum surface in the

transfer process because the GND potential of the transfer drum is greater than ­VR (V) of the OPC belt.

vi) The OPC belt is discharged by the erase lamp.

Process

OPC Belt

OV

CBV

- V

1

O

CHV

- CBV

- V

R

DBV

Charger

3

2

4

Transfer Drum

Toner

Toner

Dev. roller

1
2
3
4
5

DBV

CBV
CHV
DBV

- VR

GND

Charging Process
Exposing Process
Developing Process
Transfering Process
Cleaning (Erase)
Power Supply for OPC Belt Bias
Power Supply for Charging
Power Supply for Dev. Roller Bias
Remain voltage on the OPC Belt

5

Fig. 4-10

-11

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4

C
(

1.4.3 Details of each process

1 Charging

The charging process ensures that the OPC belt is evenly charged by the charger system.

(1) Structure of the charger unit (Refer to Fig.4-8 and Fig.4-11)

i) The charger unit is located as shown in Fig.4-8.
ii) The charger unit consists of the case, corona wire and grid.
iii) The charger unit charges the OPC belt surface to the potential -V

corona charge.

iv) The charger unit has the grid controlled to the constant voltage ZD (V) for even

charging.

(2) Process of charging (Refer to Fig.4-12.)

i) The status of the OPC belt surface before charging is -CBV (V).
ii) The charger unit charges the OPC belt surface evenly to -V

negative charge.

(V) with the

0

(V) by generating a

0

ZD

Grid

CBV CHV

Fig. 4-11

Corona wire

Case

-V

0

leaning

Blade)

Charging

Fig. 4-12

-12

HL-3450CN SERVICE MANUAL

4

2 Exposing

The exposing process means that the OPC belt surface is exposed to the laser beam to form
an electrostatic latent image.

(1) Structure of scanner unit

i) The scanner unit is located as shown in Fig.4-8.
ii) The source of the laser beam is a semiconductor laser.
iii) The laser light is scanned onto the OPC belt by converting the laser light to a beam

of light through the lens and reflective mirror to form an electrostatic latent image.

(2) Process of exposing (Refer to Fig.4-13.)

i) The OPC belt surface has been charged to the potential -Vo (V) in the charging

process.
ii) The laser light is scanned at right angles to the forward direction of the OPC belt.
iii) High speed switching of the laser is made according to the transmitted image data.
iv) The charge of the areas radiated by the laser light is reduced to the potential -VR

(V).
v) An invisible electrostatic latent image is formed on the OPC belt as shown in Fig. 4-

13.

-V

R

-V

O

Charging

Exposing

Fig. 4-13

-13

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4

D

T

3 Developing

The developing process means that an electrostatic latent image on the OPC belt is made
visible by depositing toner onto the exposed areas of the OPC belt.

(1) Structure of the Toner Cartridge (Refer to Fig.4-8 & 4.14.)

i) The toner cartridge is located as shown in Fig.4-8.
ii) Four toner cartridges are made available from the top to bottom in the order black,

yellow, magenta and cyan.
iii) Each color toner is loaded in the corresponding toner cartridge.

(2) Process of Developing (Refer to Fig.4-8, 4-14, 4-15, and 4-16)

i) Toner adheres to the developer roller of the toner cartridge.
Developing is processed by this roller contacting the OPC belt surface.
ii) The developer roller has been biased to the potential -DBV (V). Fig.4-15 describes

the relationship established between the potential of the toner, the potential -V

at the non-exposed area of OPC belt and the potential -VR (V) on the exposed area

of the OPC belt.
iii) Developing is processed by the toner adhering to the OPC belt due to the attraction

between the potential of the toner and the potential -VR (V) on the exposed area of

the OPC belt. A visible Toner image is formed on the OPC belt.
iv) No developing takes place on the non-exposed area because the potential of the

toner and that of the OPC belt is the same polarity and therefore repel each other.

(V)

0

OPC belt

eveloper roller

Toner

oner cartridge

Fig. 4-14

-14

HL-3450CN SERVICE MANUAL

4

D

T

T

eveloper roller

(-CBV) + (-DBV)

oner

(-CBV)

OPC belt

CBV

DBV

Fig. 4-15

oner (M)

YM

Exposing

Developing

Fig. 4-16

C

K

-15

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4

T

A

R

4 First Transfer (Drum)

The first transfer process means that the toner image on the OPC belt is transferred onto the
transfer drum.

(1) Structure of the Transfer Drum (Refer to Fig.4-8.)

i) The drum is located as shown in Fig.4-8.
ii) Material of the drum is aluminum.
iii) Semiconductor rubber is used to provide the drum surface as shown in Fig.4-17.
iv) The transfer drum rotates by contacting and synchronizing with the OPC belt.

ransfer Drum

luminum

ubber

Fig. 4-17

-16

HL-3450CN SERVICE MANUAL

4

R

R

B
(

B
(

(2) First Transfer Process (Refer to Fig.4-18.)

i) The OPC belt has been through the development process and contacts and

synchronizes with the transfer drum.
ii) The OPC belt has been biased to the potential of -CBV (V). The potential of the

transfer drum is nearly GND.
iii) Toner on the OPC belt is moved onto the transfer drum due to the difference of

potential between the OPC belt and the transfer drum.
iv) Toner that has been developed by each color in sequence is moved from the OPC

belt onto the transfer drum and the color toner images overlap on the transfer drum.
v) Upon completion of the drum transfer process, the complete toner image is

transferred onto paper in the paper transfer process.

OPC belt

esidual charge

esidual toner

elt cleaning

Blade)

elt discharging

Erase lamp)

Drum transferring

Fig. 4-18

-17

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4

B
(

B
(

5 Belt Discharging (Erase Lamp)

The belt discharging process means that upon completion of the drum transfer process, an
LED light is radiated onto the OPC belt prior to mechanically cleaning the belt to discharge
the residual charge.

(1) Structure of Erase Lamp

i) The erase lamp is located as shown in Fig.4-8.
ii) The light source of the erase lamp is 24 light emitting diodes (LEDs).

(2) Process of Discharging (Refer to Fig.4-19.)

i) Though the toner image was transferred to the transfer drum in the drum transfer

process, there is still a residual charge on the OPC belt.
ii) The residual charge (-VR) on the OPC belt is discharged by the radiation of the

erase lamp light prior to cleaning the belt.

elt cleaning

elt discharging

Erase lamp)

Drum transferring

Blade)

Fig. 4-19

-18

HL-3450CN SERVICE MANUAL

4

B
(

B
(

6 Belt Cleaning

The belt cleaning process means that the residual toner adhering to the OPC belt surface is
mechanically scavenged.

(1) Structure of Belt Cleaning

The blade for the belt cleaning is located relative to the OPC belt cartridge as shown in
Fig.4-8.

(2) Process of Belt Cleaning (Refer to Fig.4-20.)

i) There is residual toner on the OPC belt as it has not been completely transferred in

the drum transfer process.
ii) Residual toner is mechanically scavenged by the blade edge.
iii) The scavenged residual toner is collected in the waste toner pack by the waste

toner feeder.

elt cleaning

elt discharging

Erase lamp)

Drum transferring

Blade)

Fig. 4-20

-19

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4

T

P

V

T

7 Second Transfer (Paper)

The second transfer process is where the toner image on the transfer drum is transferred
onto the transported paper.

(1) Second Transfer Structure

i) The transfer roller for the paper transfer is located as shown in Fig.4-8.
ii) The transfer roller is normally kept out of contact with the transfer drum until the

second transfer process starts.
iii) The transfer roller is positively biased by the power supply THV.
iv) The transfer roller is in contact with the transfer drum only in the second transfer

process.
v) Transported paper passes between the transfer roller and transfer drum.

(2) Second Transfer Process (Refer to Fig.4-21.)

i) Paper is transported and is synchronized with the transfer drum.
ii) The transfer roller operates and is synchronized with the transported paper and is

in contact with the transfer drum through the transported paper.
iii) The transported paper passes between the transfer roller and transfer drum.
At this time the positive high voltage (THV) is fed to the transfer roller.
iv) Negatively charged toner on the transfer drum is moved to the positively charged

paper.
v) The transported paper with the toner transferred to it is moved to the paper

discharging process.

Paper discharger

Transfer roller

VAC

THV

Transfer drum

oner image

AC: Power supply for paper

discharging

HV: Power supply for transfer

roller bias

aper

Fig. 4-21

-20

HL-3450CN SERVICE MANUAL

4

T

T

P

8 Paper Discharging

The paper discharging process is where the transported paper onto which the toner transfer
has been completed is separated from the transfer drum by applying an AC charge to the
paper.

(1) Structure of Paper Discharger (Refer to Fig.4-22.)

i) The AC charger unit for discharge the paper is located as shown in Fig.4-8.
ii) The AC charger unit consists of the case and a charger wire.
iii) A high alternating voltage (VAC) is fed to the AC charger unit.

(2) Process of Paper Discharging (Refer to Fig.4-22.)

i) The paper adheres to the transfer drum in the transfer process.
ii) The paper is neutralized (discharged) in terms of any electrical charge by the

alternate voltage generated by the discharger.
iii) Paper is separated from the transfer drum and subsequently transported to the

fusing (fixing) process.

Paper discharger

Transfer roller

VAC

THV

ransfer drum

oner

aper

Fig. 4-22

-21

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4

D

W

D

9 Drum Cleaning

The drum cleaning process is where the residual toner on the transfer drum is removed.

(1) Structure of Drum Cleaning (Refer to Fig.4-23.)

i) The drum cleaning unit is located as shown in Fig.4-8.
ii) The drum cleaning brush is a semiconductor type so that the brush can clean the

surface of the rotating transfer drum. The Drum cleaning brush is kept out of

contact with the transfer drum when the print image on the transfer drum is being

created.
iii) The drum cleaning roller is positively biased by the positive voltage FCBV (V).
iv) FCBV (V) is fed to the cleaning brush in contact with the roller and the cleaning

brush is self-biased by the resistance of the brush.
v) The drum cleaning roller rotates in contact with the drum cleaning brush.

(2) Process of Drum Cleaning (Refer to Fig.4-23.)

FCBV: Cleaning roller

i) There is residual toner on the surface of the transfer drum after the paper transfer

process.
ii) The Drum cleaning brush is positively self-biased and so the negatively charged

residual toner is removed from the surface of the transfer drum onto the drum

cleaning brush.
iii) The Drum cleaning roller has been biased to the positive voltage FCBV (V). As the

cleaning brush rotates, the residual toner absorbed into the brush from the transfer

drum is attracted by the positive FCBV (V) voltage on the roller and adheres to the

surface of the drum cleaning roller.
iv) Waste toner adhering to the surface of the drum cleaning roller is scavenged by the

cleaning blade and collected into the waste toner pack by the waste toner feeder.

Power supply for
fuser cleaner bias

Cleaning brush

Residual

Toner

FCBV

Transfer drum

Fig. 4-23

rum cleaner

est toner feeder

rum cleaning unit

-22

4

1.5 Scanning System

This printer employs a semiconductor laser diode as a light source. This laser diode is
switched according to the transmitted image data (video signal).

The generated laser light scans over the OPC belt through a polygon mirror and lens, by
which method electrostatic latent images will be formed on the OPC belt.

(1) Structure of the Scanning System (Refer to Fig.4-24.)

The scanner unit is located as shown in Fig.4-8.
The scanner unit consists of the following parts;

Scanner Unit: Light emitting source incorporating a laser diode.

c

Cylinder lens: Condenser for the laser beam.

d

Polygon mirror: Hexahedral mirror for scanning the laser beam.

e
f

F-6 lens:
Scanner motor: Motor to rotate the polygon mirror.

g

Mirror: Reflecting mirror for the laser beam path.

h

LDC: Laser diode control circuit.

i

PD: Beam detector.

j

BTD mirror: Beam timing detector mirror to guide the laser beam

k

HL-3450CN SERVICE MANUAL

Focus lens for the laser beam.

to the PD sensor.

Scanner Unit box

Dust proof glass

Developer belt

6

4

2

5

3

9

2

8

1

7

Fig. 4-24

-23

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4

(2) Specification:
Specification of the scanner unit is as follows;

Item Specifications
Rated output of laser diode 5 mW.
Wave length of laser beam Approx.785nm.
Scanning density 600dpi
Scanning width 310mm
Scanner motor speed 24,072rpm
Number of polygon mirror faces 6

-24

4

1.6 Paper Transportation System

1.6.1 Outline

This printer employs automatic paper feeding from the media cassette.
When toner images are formed on the transfer drum through the operations of the print

system and transfer system, paper is fed by the pick-up roller and transported to the
register roller. The transported paper is further transported to the transfer, fuser and
exit parts by the register roller synchronizing with the rotation of the transfer drum.

1.6.2 Structure of paper transportation system

The paper transportation system consists of the following parts;

Media cassette: Case to accommodate paper to be fed automatically.

c

Paper pick-up roller: Roller to feed sheets of paper one by one, preventing

d

multi-feed.

Register roller: Roller to transport papers synchronized with the

e

transfer drum.

HL-3450CN SERVICE MANUAL

Transfer part: Print processing part consisting of transfer drum and

f

transfer roller to transfer the toner image onto the
paper.

Paper discharger unit: Corona generator to generate AC corona for

g

separating paper from the transfer drum.

Fusing unit: Mechanical part to fuse the toner image with heat

h

rollers and fix it on the paper.

Paper exit unit: Mechanical part to exit the fused paper from the

i

printer.

Paper exit roller: Roller to feed paper from the printer.

j

i

h

j

K
Y
M
C

g

f

e

d

c

Fig. 4-25

-25

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4

1.7 Fusing Unit

The fusing unit employs a thermal fusing system using heater lamps in the rollers. Paper
carrying the combined toner image passes between the heat rollers. Heat and pressure is
applied to the paper when passing between the heat rollers so that the toner image is melted
and fused onto the paper.

1.7.1 Structure

The fusing unit consists of the following component parts; (Refer to Fig.4-26.)

Fuser roller: incorporates a heater lamp.

c

Back-up roller: is a pressure roller and incorporates a heater

d

Fusing heaters: halogen lamps to heat the rollers.

e

Thermistor: is a sensor to detect the temperature of the

f

Thermal fuse: prevent the fuser roller from being

g

lamp.

fuser roller’s surface.

excessively heated up.

Oil bottle: contains silicone oil for fusing.

h

Fuser cleaner: cleans the fuser roller.

i

7

2

4

1

6

5

3

Fig. 4-26

-26

4

1.7.2 Fusing process

M
Y
C

R
M
G

Silicone oil supplied from the oil bottle is applied to the surface of

c

fuser roller.
The toner image has been transferred onto the paper, but not yet

d

fused.
Transported paper passes between the heater roller and back-up

e

roller.
Each roller is heated up to approx.150qC, and receives

f

approximately 156N pressure from the opposite heat roller.
When the paper carrying the toner images passes between the

g

two heat rollers, the toner images are melted and fused on the
transported paper.

The paper carrying the fused image is separated from the heat

h

rollers, and ejected from the printer.

HL-3450CN SERVICE MANUAL

: Magenta toner
: Yellow toner
: Cyan toner

Toner Image

(a) Before Fusing

(b) After Fusing

M
Y

R

Fig. 4-27

C

MY

: Red

: Magenta
: Green

M

G

Paper

Fixed toner

-27

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4

2. STRUCTURE OF THE CONTROL SYSTEM

2.1 Basic Structure - Electrical System and Functions

Most of the main electrical parts of this printer are controlled by the MCTL (engine controller)
PWB.

<Structure of the sequence control>
The basic structure of the sequence control is shown in Fig.4-28.

Print Process Control: To control the print process from the paper feed

c

through to the paper exit.

Laser Output Control: To automatically control the laser output.

d

Fuser Temperature Control: To control the fixer heater so that the

e

temperature of the fuser roller and back-up
roller will be correct.

Toner Sensing Control: To control the sensing of the toner empty

f

status.

Interface Control:

g

(Video Signal)
Control Panel Indicator: To display the printer operational status on the

h

Error Control: To control the safety stop procedures when

i

To process the input and output signals to and
from the external controller (host).

control panel indicator.

errors occur in the printer.

-28

HL-3450CN SERVICE MANUAL

4

Host Computer

I/F
Controller

Video
Controller

Cleaning Roller
Sensor

Oil Sensor

Fusing Unit

Control

Panel

I/F
Control

Main

Motor

DC Power

Supply Unit

Cooling

Fan

Cooling

Fan

Belt

Sensor

MCTL (Engine Controller)

Sequence Control
Temperature Control

Toner Connection Control
Control Panel Control
Error Clearance Program

High Voltage Unit

Interlock Switches

Fig. 4-28

Drum

Sensor

DM

ATC (4 pcs.)

YMCK

CPU

Paper Empty Sensor
Paper Feed Sensor
Toner Empty Sensor
Paper Size Sensor
Paper Exit Sensor
OHP Sensor
Drum Jam Sensor

Cleaning Roller Sensor

Scanner

Motor

LDU

Laser Control

Drum Encoder
Belt Sensor
Oil Sensor
Paper Full Sensor
Waste Toner Sensor
Toner Key Sensor
Developer Sensor
Temperature Sensor

PD

-29

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4

<Layout & Function of the Electrical Parts>
(1) Print PCB (Refer to Fig. 4-29.)

No. Name Function

1 Video controller PCB

To receive the print data from the host computer,
convert it into image data and then send the
printing image data to the MCTL PWB.

2

Engine controller PCB

(MCTL PWB)

To control the sequence of processes of the
printer: Fusing Temperature Control, Laser Output
Control, Control Panel Indications, Toner Empty
Sensing Control, Error Processing Control,
Interface Control.

3

Control panel PCB

(Panel PWB)

To display the printer’s operation status and
support the control panel switches.

4 LDU PCB

5 PDU PCB

To control the drive and output to the laser diode
in the scanner unit.

To sense the emission of the laser diode and the
beam position in the scanner unit.

6 Erase lamp To discharge the OPC belt with the LEDs.

To send the signals from the sensors to the MCTL

7 IOD1 PWB

PWB, and to drive the outputs from the MTCL
PWB to the motors, clutches and solenoids.

8 IOD2 PWB - Ditto -

9

10

DC power supply

(LVPS) PCB

High-voltage power

supply (HVU) PCB

To provide the printer with the power for printer
control.

To provide the printer with the high voltage power
supplies necessary for the printing process.

-30

HL-3450CN SERVICE MANUAL

4

4

6

5

Layout of PCBs

10. High-voltage power
supply (HVU) PCB

1. Video
controller PCB

. Erase lamp

3. Control panel PCB

(Panel PWB)

8. IOD2 PWB

7. IOD1 PWB

2. Engine controller PCB
(MCTL PWB)

. LDU PCB

9. Power supply (LVPS) PCB
. PDU PCB

Fig. 4-29

-31

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4

7

1

(2) Motors (Refer to Fig.4-30.)

No. Name Code Function

1 Main motor MM

Developing motor

2

(Developer drive motor)

DM

To drive the OPC belt and the paper
transport system.

To drive the toner cartridge and the
developing system.

3 Scanner motor SCM To scan the laser beam

4

5

6

7
7-1
7-2
7-3

Ozone fan motor
(Cooling fan motor)

Fuser fan motor
(Cooling fan motor)

Controller fan motor
(Cooling fan motor)

Interlock swit ch
Front cover switch
Top cover switch
Rear access cover

OZFAN

(OZ)

HTFAN

(EX)

CTLFAN

(PS)

DSW1
DSW2
DSW3

To exhaust the ozone from the
printer (charger unit).

To exhaust the heat of the fusing

To exhaust the heat of the power
supply unit and Interface Controller.

These are the safety interlock
switches that operate when the
covers are opened.

(TR unit cover) swit ch

Layout of Motors

7-2. Top cover switch

6. Controller fan motor

7-3. Rear access

cover switch

4. Ozone fan motor

5. Fuser fan motor
. Main Motor

2. Developing motor

3. Scanner motor

-1. Front cover switch

Fig. 4-30

-32

4

(3) Clutches (Refer to Fig.4-31.)

No. Name Function

To feed paper by coupling the feed roller to the

1 Paper feeding clutch

main gear unit at the correct timing for paper
feeding.

To transport paper by coupling the register roller to

2 Registration clutch

the main gear unit synchronized with the rotation of
the transfer drum.

HL-3450CN SERVICE MANUAL

3 Fuser clutch

4 Cleaner clutch

5 a 8

Developer clutch

9 TR ca m clutch

10 Cleaner cam clutch

To drive the fusing rollers by coupling the fusing
unit to the main gear unit.

To drive the brush of the drum cleaner by coupling
the cleaner clutch to the main gear unit at the
correct timing for drum cleaning.

To drive the magnetic roller of the desired color
toner cartridge by coupling that toner cartridge to
the developer gear unit during developing.

To make the transfer roller contact the transfer
drum surface at the time of the second transfer.

To make the drum cleaner contact the surface of
the transfer roller at the correct timing for drum
cleaning.

NOTE: The cleaner cam clutch is identical to the
TR cam clutch.

-33

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4

Layout of Clutches

10

3

4

9

2

1

8

7

6

5

Fig. 4-31

-34

HL-3450CN SERVICE MANUAL

4

(4) Sensors

No. Name Code Function

1 Paper size sensor PSU Photo sensor to detect the paper size.

2 Paper feeding sensor PS 1

3 Paper exit sensor PS 2

4 Paper empty sensor PS 3

5 Oil sensor OIL

6 OHP sensor OHP

7 Drum jam sensor DPJ

8 Drum encoder sensor PS 4

9 Belt sensor PBS

Photo sensor to detect when paper is
fed from the media cassette.

Photo sensor to detect that paper is
exited from the paper exit unit.

Photo sensor to detect if paper is
loaded in the media cassette.

Photo sensor to detect if the fusing
unit oil is empty.

Photo sensor to detect if media in the
media cassette is an OHP.

Photo sensor to detect if paper is
wound around the transfer drum.

Photo sensor to detect rotation of the
transfer drum.

Photo sensor to detect the home
position of the OPC belt.

10 Toner sensor TPD/TTR

Photo sensor to detect if the toner is
empty for each toner cartridge.

11 Waste toner sensor

WTS Photo sensor to detect if the waste

toner bottle is full of toner.

12 Home position sensor

GHP1/

GHP2

13 Cleaning roller sensor PS 5

Photo sensor to detect the position of
the toner cartridge.

Photo sensor to detect if the fuser
cleaner is fitted in the fixing unit.

14

Temperature sensor

TH

for fusing unit

15 Paper full sensor PS 6

Thermistor to detect the fuser
temperature.

The sensor to detect when the paper
eject tray is full of paper.

16 Toner key sensor TNK

The sensor to detect the key provided
in the toner cartridge.

-35

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4

7

1

3

Layout of Sensors

14. Temperature sensor
(Thermistor to detect)

. Paper exit sensor

13. Cleaning roller sensor

15. Paper full sensor

5. Oil sensor

9. Belt sensor

8. Drum encoder sensor

6. OHP sensor

2. Paper feeding sensor

4. Paper empty sensor

. Drum jam sensor

0. Toner sensor

12. Home position sensor

11. Waste toner sensor

1. Paper size sensor

16. Toner key sensor

Fig. 4-32

-36

4

2.2 Control System - Control of the Print Process

A Micro CPU mounted on the MCTL PWB controls the print processes.

<Print Sequence Diagram>

HL-3450CN SERVICE MANUAL

Host Computer

I/F
Controller

Video
Controller

Cleaning Roller
Sensor

Oil Sensor

Fusing Unit

Control

Panel

I/F
Control

Main
Motor

DC Power

Supply Unit

Cooling

Fan

MCTL (Engine Controller)

Sequence Control
Temperature Control

Toner Connection Control
Control Panel Control
Error Clearance Program

Interlock Switches

Cooling

Fan

Sensor

High Voltage Unit

Fig. 4-33

DM

Belt

Drum

Sensor

ATC (4 pcs.)

YMCK

CPU

Paper Empty Sensor
Paper Feed Sensor
Toner Empty Sensor
Paper Size Sensor
Paper Exit Sensor
OHP Sensor
Drum Jam Sensor

Cleaning Roller Sensor

Scanner

Motor

LDU

Laser Control

PD

Drum Encoder
Belt Sensor
Oil Sensor
Paper Full Sensor
Waste Toner Sensor
Toner Key Sensor
Developer Sensor
Temperature Sensor

-37

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4

(1) Control Block Diagram (Refer to Fig.4-33.)

No. Name Function

1 Sequence Control

2 Temperature Control

3 Toner Empty Sensing Control

4 Control Panel Control

5 Error Processing Control

To control the sequence of printer
operations.

To control the temperature of the fixing
unit.

To detect the toner empty status of each
toner cartridge.

To control the control panel indications
and the operational signals.

To sense errors occurring in the printer
and control the stop procedures.

To control the receipt and transmission of

6 Interface Control

the interface signals from the external
controller.

7 Laser Control To control laser scanning and laser power.

-38

HL-3450CN SERVICE MANUAL

4

(2) Laser Drive Control Circuit

Laser Drive Control Circuit (LDC) consists of the video signal input circuit, laser drive
circuit, laser diode, output sensing circuit and output control circuit, as shown in Fig.4-

34.

<Operation>
(1) When the video signal is received, the laser drive control circuit switches the laser

diode according to the video signal data.

(2) The radiated laser beam is sensed by the photo detector (PD) and the signal is fed

back to the output control circuit.

(3) The output control circuit controls the laser output to make the level constant by

comparing the laser output with the feed-back value transmitted from the output
sensing circuit.

(4) The scanning laser beam is sensed by the beam detector (PD), then the beam

detecting timing (BDT) signal is output.

MCTL PWB

PRINT Signal

VIDEO Signal

Frequency Control
Circuit

Beam Scanning
Control Circuit

Synchronizie
Control Circuit

PD

BDT

LDC PCB

OPC Belt

Scanner Lens

Scanner Motor

Laser

Fig. 4-34

-39

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4

(3) Control of the Fusing Temperature

Each roller of the fusing unit is controlled to maintain the appropriate temperature so
that toner will be fixed correctly onto the print paper.

<Basic Structure of Temperature Control (Fig.4-36)>

FLS: Thyristor to switch the power supply to the heat lamp.
TFU1/TFU2: Temperature fuse to shut down the circuit for safety when the

temperature becomes too hot within the fixing unit.

TH: Temperature sensor to detect the surface temperature of the

heat roller (HR).

RY: Relay to prevent further heating when it becomes hotter than

the set temperature within the fixing unit.

GA/CPU: Process circuit to control the temperature signal (micro

computer).
CM1: Sensor circuit for temperature signal (for ACOFF signal).
CM2: Sensor circuit for temperature signal (for HON signal).
CM3: Sensor circuit for temperature signal (for processing).
Q: Sensor circuit for shut-down by the thermistor (for THERR

signal).
HR: Heat lamp for the heat roller.
BR: Heat lamp for the back-up roller.

< Signal Functions >

HON-N To turn on/off the heater inside the fuser roller.
ACOFF To turn off the relay RY1 if overheat occurs.
THERR To detect the shut-down by the thermistor.
AD To convert the temperature sensing signal to AD.

<Controlled Temperature and Safety>

TPS

TA

Temperature

( )

C

Time

C

150 TS

Fig. 4-35

-40

HL-3450CN SERVICE MANUAL

4

<Basic Structure of Fuser Control>

RY-1

ACOFF-P

RY-1

CM3

CM2

CM1

Q

AD

THERR ACOFF

HON

HON-N

PC

FLS

TFU

BR

1

TFU

HR

2

Fusing Unit

GA/CPU

Fig. 4-36

-41

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4

TS:

To maintain the temperature for fixing of the toner at 150qC by
turning the thyristor on and off.

TA:

Reference temperature ( approx. 185qC) to identify that it is
excessively hot inside the fusing unit. When it reaches this
point, the relay RY turns off, the power supply to the heat lamp
is shut down and the printer stops operating.

TPS: Limit temperature when the thermal fuse will start to melt and

shut down the power supply to the heat lamp if the temperature
control circuit should break down. When the thermal fuse
melts, the printer will stop operating.

<Safety Control by Temperature Control Signal>

H0: When the THERR signal is input, the control panel indicates

“H0”, and the printer will stop operating.

H2: If the temperature of the fixing unit does not reach the required

point “T1” after a certain time, the control panel indicates “H2”
and the printer will stop operating.

H3: If the “Heater On” signal still continues after a certain time, the

control panel indicates “H3”, and the printer will stop operating.

H4: If the temperature within the fusing unit becomes unusually hot

and when ACOFF signal is input, the control panel indicates
“H4”, and the printer will stop operating.

-42

HL-3450CN SERVICE MANUAL

4

(

4) Interface Control
<General>

(a) Interface Type

The video interface handles laser image data that corresponds to dots for printing but
does not store image data in a buffer. The video data signals of the input image data
switches the semiconductor laser diode to form a print image.

(b) Interface Connection

Video Interface /

Operator

Panel

DC Power Supply Connector

Duplex unit

(Option)

Lower Tra y(1)

Unit (Option)

LowerTray(2)

Unit (Option)

Printer
Engine

Controller

DC Power Supply

Laser Printer

Controller

(LPC)

[Customer design]

Host

System

Fig. 4-37

The interface connector of this laser printer is connected to the host system as shown
in Fig.4-37.

-43

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4

(c) Interface Circuit (Printer side)

Table 4-1: Interface Circuit

No. Interface Circuit Signal Name

1

2

x

VIDEO-N

x

VIDEO-P

x

HSYNC-N

x

HSYNC-P

x

PRREQ-N

3

4

x

COMMAND-N

x

ID1-N

x

ID2-N

x

VSYNC-N

x

IREADY-N

x

STATUS-N

x

KEY-STATUS-N

-44

HL-3450CN SERVICE MANUAL

4

(d) Connector Pin Assignment

The connector in the printer to connect to the controller board is type 128A-064S2B­L14A(DDK) or the equivalent.

Table 4-2: Connector Pin Assignment

Pin No. Signal Name Pin No. Signal Name

1A PSGND 1B +5V
2A PSGND 2B +5V
3A PSGND 3B +5V-D
4A PSGND 4B +5V-D

5 PSGND 5B +5V-D
6A PSGND 6B +5V-D
7A PSGND 7B +5V-D
8A PSGND 8B +5V-D
9A VIDEO-P 9B VIDEO-N

10A RET (GND) 10B Reserve
11A HSYNC-P 11B HSYNC-N
12A ID2-N 12B Reserve
13A RET (GND) 13B VSYNC-N
14A RET (GND) 14B Reserve
15A RET (GND) 15B STATUS
16A RET (GND) 16B IREADY-N
17A RET (GND) 17B Reserve
18A RET (GND) 18B COMMAND
19A RET (GND) 19B PRREQ-N
20A RET (GND) 20B Reserve
21A ID1-N 21B Reserve
22A RET (GND) 22B KEY_STATUS-N
23A Reserve 23B Reserve
24A Reserve 24B Reserve
25A RET (GND) 25B Reserve
26A RET (GND) 26B Reserve
27A RET (GND) 27B Reserve
28A RET (GND) 28B Reserve
29A RET (GND) 29B Reserve
30A RET (GND) 30B Reserve
31A RET (GND) 31B Reserve
32A RET (GND) 32B Reserve

-45

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS

4

2.3 Main PCB (Video Controller PCB)

2.3.1 Outline

The main PCB consists of the circuits which perform the following functions;

x

Receive the printing data from the computer.

x

Convert the received data to the bitmap data such as characters or graphics.

x

Control the engine and send the generated bitmap data as a video signal.

The control panel is controlled by communicating with the engine CPU to display LCD
messages, light the LEDs and display the button status, etc.

The power for the Main PCB is supplied from the engine through the engine interface
connector.

-46

4

<Main PCB Block Diagram>

HL-3450CN SERVICE MANUAL

CDCC I/F

RJ45

10/100Base-TX

USB

Compact Flash

+5v

Network Board

+5v

+3.3v

NC-4100

IDE
HARD DISK

CompactFlash Data BUS

+5v

HCT245

Regurator
PQ30RV31

Regurator

PQ070XZ01Z

PCI-BUS

IDE Data BUS

HCT245

+3.3v+5v

+1.65v+3.3v

+5v/+3.3v

Gate Array

SLAC099HF1A

Local Data BUS

+3.3v / +1.65v

CPU

TMPR4955-266

(TX4955 266MHz)

+5v/+3.3v

CPU-Address/Data MultiBUS

ASIC
MB87F4561

CS,DQM

RAS,CAS

WE,MA

Data BUS

LCX16245

Address BUS

Clock
Generator

C8750

LCX16347

66MHz(CPU,SDRAM)
33MHz(PCI)
48MHZ(GA)

+3.3v

SLOT2

DIMM
(100pin)
3slots
348MB MAX

+3.3v +3.3v

MASK
ROM
32M x2
(8MB)

SN75C1168

SLOT1

Hsync

Video

SLOT0

Flash
ROM
32M x2
(8MB)

ENGINE I/F

+5v

EEPROM
M24C64
64kbit

Address BUS

Command,PrReq

Vsync,Status,Iready,KeyStatus

+5v

GND

-47