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R

LASER PRINTER

SERVICE MANUAL
MODEL:HL-720/730/730Plus

© Copyright Brother 1996 All rights reserved. No part of this publication may be reproduced in any form or by any means without permission in writing from the publisher. Specifications are subject to change without notice. Trademarks: The brother logo is a registered trademark of Brother Industries, Ltd. Apple,the Apple Logo,and Macintosh are trademarks,registered in the United States and other countries,and True Type is a trademark of Apple computer, Inc. Epson is a registered trademark and FX-80 and FX-850 are trademarks of Seiko Epson Corporation. Hewlett Packard is a registered trademark and HP Laser Jet II, IIP, and IID are trademarks of HewlettPackard 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.

PREFACE
This service manual contains basic information required for after-sales service of the laser printer (here-after referred to as "this machine" or "the printer"). This information is vital to the service technical in maintaining the high print quality and performance of the printer. This service manual covers both HL-720 and HL-730/730Plus. This manual consists of the following chapters: CHAPTER I: FEATURES AND SPECIFICATIONS Features, specifications, etc. THEORY OF OPERATION Basic operation of the mechanical system, the electrical system and the electrical circuit, and their timing. DISASSEMBLY AND REASSEMBLY Procedures of disassembling and reassembling the mechanical system. TROUBLESHOOTING Reference values and adjustments, troubleshooting for image defects, troubleshooting for malfunctions, etc. Connection diagrams, PCB circuit diagrams.

CHAPTER II:

CHAPTER III:

CHAPTER IV:

APPENDICES:

Note:

There are each captions for HL-720 and HL-730/730Plus to divide this manual according to the contents. You can fin the captions under the headings. Please pay attention to them On the other hand, the headings have no captions that means the contents are common to HL720 and HL-730/730Plus.

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 quality performance and for fostering the practical ability to find the cause of problems.

CONTENTS
CHAPTER I FEATURES AND SPECIFICATIONS....................................................... I-1
1. SYSTEM REQUIREMENTS................................ ................................ ................................ I-1 2. FEATURES ................................ ................................ ................................ ....................... I-1 3. SPECIFICATIONS ................................ ................................ ................................ ..............I-4
3.1 3.2 3.3 3.4 3.5 3.6 3.7 4.1 4.2 4.3 Printing.......................................................................................................................................I-4 Functions ...................................................................................................................................I-5 Electrical and Mechanical ..........................................................................................................I-6 Paper Specification ....................................................................................................................I-7 Print Delivery..............................................................................................................................I-7 Paper .........................................................................................................................................I-7 Effective Printing Area ...............................................................................................................I-8 Laser Safety (110 - 120V Model only)) ....................................................................................I-10 CDRH Regulations (110 -120V Model only) ............................................................................I-10 Caution for Laser Product........................................................................................................I-11

4. SAFETY INFORMATION ................................ ................................ ................................ ..I-10

CHAPTER II THEORY OF OPERATION .................................................................... II-1
1. ELECTRONICS................................ ................................ ................................ ..................II-1
1.1 1.2 1.3 General Block Diagram.............................................................................................................II-1 Main PCB Block Diagram .........................................................................................................II-3 Main PCB..................................................................................................................................II-5
1.3.1 1.3.2 1.3.3 1.3.4 1.3.5 1.3.6 1.3.7 1.3.8 1.3.9 1.3.10 1.3.11 CPU Core ................................................................................................................................. II-5 ASIC ......................................................................................................................................... II-7 ROM ....................................................................................................................................... II-13 DRAM..................................................................................................................................... II-13 Optional RAM ......................................................................................................................... II-15 Optional Serial I/O ................................................................................................................. II-16 EEPROM ................................................................................................................................ II-16 Reset Circuit........................................................................................................................... II-17 CDCC I/O ............................................................................................................................... II-18 Engine I/O .............................................................................................................................. II-19 Paper Feed Motor Drive Circuit .............................................................................................. II-21

1.4 1.5 2.1 2.2

Panel Sensor PCB ..................................................................................................................II-22 Power Supply..........................................................................................................................II-23 Overview of printing mechanism............................................................................................II-24 Paper Transfer ........................................................................................................................II-25
2.2.1 Paper Supply.......................................................................................................................... II-25 2.2.2 Paper Registration.................................................................................................................. II-25 2.2.3 Paper Eject............................................................................................................................. II-26

2. MECHANICS................................ ................................ ................................ .................... II-24

2.3 2.4

Sensors...................................................................................................................................II-27
2.3.1 Cover Sensor ......................................................................................................................... II-27 2.3.2 Toner Empty Sensor .............................................................................................................. II-27

Drum Unit................................................................................................................................II-28
2.4.1 2.4.2 2.4.3 2.4.4 2.4.5 Photosensitive Drum .............................................................................................................. II-28 Primary Charger ..................................................................................................................... II-28 Developer Roller..................................................................................................................... II-28 Transfer Roller........................................................................................................................ II-28 Cleaner Roller ........................................................................................................................ II-28

i

2.4.6 Erase lamp ............................................................................................................................ II-28

2.5

Print Process ..........................................................................................................................II-28
2.5.1 2.5.2 2.5.3 2.5.4 2.5.5 2.5.6 Charging................................................................................................................................. II-28 Exposure stage ...................................................................................................................... II-29 Developing ............................................................................................................................. II-30 Transfer .................................................................................................................................. II-30 Drum Cleaning Stage ............................................................................................................. II-31 Erasing Stage......................................................................................................................... II-31

CHAPTER III DISASSEMBLY AND REASSEMBLY ................................................. III-1
1. SAFETY PRECAUTIONS................................ ................................ ................................ ..III-1 2. DISASSEMBLING FLOW................................ ................................ ................................ ..III-2 3. DISASSEMBLING PROCEDURE ................................ ................................ ..................... III-3
3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 Drum Unit.................................................................................................................................III-3 Top Cover ................................................................................................................................III-3 Multi-purpose Paper Tray Assy ..............................................................................................III-4 Fixing Unit ................................................................................................................................III-5 Scanner Unit ............................................................................................................................III-7 Main PCB Assy .......................................................................................................................III-7 Base Plate Assy.......................................................................................................................III-8 Panel sensor PCB Assy...........................................................................................................III-8 Low-voltage Power Supply PCB Assy .....................................................................................III-9 High-voltage Power Supply PCB Assy ....................................................................................III-9 Fan Motor...............................................................................................................................III-10 Drive Unit ...............................................................................................................................III-10 Main Motor Assy and Motor Heat Sink ..................................................................................III-11 Gears and Solenoid ...............................................................................................................III-11 Tray Extension .......................................................................................................................III-12 Paper Eject Tray Assy ...........................................................................................................III-12

4. PACKING................................ ................................ ................................ ........................ III-13

CHAPTER IV TROUBLESHOOTING......................................................................... IV-1
1. INTRODUCTION................................ ................................ ................................ .............. IV-1
1.1 1.2 2.1 2.2 Initial Check ............................................................................................................................ IV-1 Basic Procedure ..................................................................................................................... IV-2 Image Defect Examples.......................................................................................................... IV-3 Troubleshooting Image Defects.............................................................................................. IV-4

2. IMAGE DEFECTS ................................ ................................ ................................ ............ IV-3

3. TROUBLESHOOTING OF MALFUNCTIONS ................................ ................................ IV-12 4. INSPECTION MODE................................ ................................ ................................ ...... IV-17
4.1 4.2 Incorporated Inspection Modes ............................................................................................ IV-17 Error codes ........................................................................................................................... IV-19

APPENDICES ............................................................................................................. V-1
1. 2. 3a. 3b. 4. 5. 6. Connection Diagram, HL-720 .................................................................................................. V-1 Connection Diagram, HL-730/730Plus .................................................................................... V-2 Main PCB Circuit Diagram (1/2), HL-720................................................................................. V-3 Main PCB Circuit Diagram (2/2), HL-720................................................................................. V-4 Main PCB Circuit Diagram (1/2), HL-730/730Plus................................................................... V-5 Main PCB Circuit Diagram (2/2), HL-730/730Plus................................................................... V-6 Panel/Sensor PCB Circuit Diagram ......................................................................................... V-7

ii

7. 8. 9. 10.

Low-Voltage Power Supply PCB Circuit Diagram 230V .......................................................... V-8 Low-Voltage Power Supply PCB Circuit Diagram 115V .......................................................... V-9 High-Voltage Power Supply PCB Circuit Diagram ................................................................ V-10 Serial No. Descriptions .......................................................................................................... V-11

iii

CHAPTERI






Check the following system requirements to setup and operate the printer: · · · · · IBM PC or compatible with 80486 SX or higher microprocessor Parallel interface (or printer port) 4 Mbytes or more of memory 10 Mbytes of space available on your hard disk for the printer driver and all fonts Microsoft Windows 3.1/3.11 or Windows 95

Caution: This printer has been designed specially for Windows 3.1/3.11 and Windows 95. It cannot work in a DOS environment such as MS-DOS.






This printer has the following features: 600 dpi Resolution and 6 ppm Printing Speed 600 dots per inch (dpi) with microfine toner and six pages per minute (ppm) printing speed (A4 or Letter size paper). User-Friendly Operation for Windows The dedicated printer driver and TrueTypeTM-compatible fonts for Microsoft® Windows 3.1 and Windows 95 are available on the floppy disk supplied with your printer. You can easily install them into your Windows system using our installer program. The driver supports our unique compression mode to enhance printing speed in Windows applications and allows you to set various printer settings including toner saving mode, custom paper size, sleep mode settings, gray scale adjustment, resolution, and so forth. You can easily set these print options through the Printer Setup Menu within the Windows Control Panel. Printer Status Monitor with Bi-directional Parallel Interface The printer driver can monitor your printer's status using bi-directional parallel communications. The printer status monitor program can show the current status of your printer. When printing, the animated dialog box appears on your computer screen to show the current printing process. If an error occurs, a dialog box will appear to let you know what to correct. For example: when your printer is out of paper, the dialog box will display "Paper Empty" and instructions for the proper corrective action. Versatile Paper Handling The printer has a multi-purpose sheet feeder and straight paper path mechanism. Using this mechanism, you can load A4, letter, legal, B5, A5, and executive sizes of paper, and various types of paper including envelopes, postcards, organizer paper, or a custom paper size. The multi-purpose sheet feeder also allows manual paper loading, so you can use labels and transparencies.



Auto Resolution Reduction When printing in 600 dpi, mode with the standard memory, the printer may not be able to print due to insufficient memory. To prevent this memory error, the printer driver automatically reduces the resolution to 300 dpi or less and for successful printing Environment-Friendly Economy Printing Mode This feature will save your printing cost by saving toner. It is useful to obtain draft copies for proof-reading. You can select from two economy modes, 25% toner saving and 50% toner saving, through the Windows printer driver supplied with your printer. Sleep Mode Sleep mode automatically reduces power consumption when the printer is not in use. The printer consumes less than 7W when in sleep mode. The time-out for auto sleep mode can be set through the Windows printer driver. Low Running Cost Since the toner cartridge is separate from the Drum Unit, you need to replace only the toner cartridge after around 2,200 pages printed, which is cost effective and ecologically friendly. Enhanced Memory Management The printer provides its own data compression technology on its printer hardware and the supplied printer driver software, which can automatically compress graphic data and font data efficiently into the printer's memory. You can avoid memory errors and print most full page 600 dpi graphic and text data, including large fonts, with the printer's standard memory.


This printer has the following features: 600 dpi Resolution and 6 ppm Printing Speed 600 dots per inch (dpi) with microfine toner and six pages per minute (ppm) printing speed (A4 or Letter size paper). User-Friendly Operation for Windows The dedicated printer driver and TrueTypeTM-compatible fonts for Microsoft® Windows 3.1 and Windows 95 are available on the floppy disk supplied with your printer. You can easily install them into your Windows system using our installer program. The driver supports our unique compression mode to enhance printing speed in Windows applications and allows you to set various printer settings including toner saving mode, custom paper size, sleep mode settings, gray scale adjustment, resolution, and so forth. You can easily set these print options through the Printer Setup Menu within the Windows Control Panel. Printer Status Monitor with Bi-directional Parallel Interface The printer driver can monitor your printer's status using bi-directional parallel communications. The printer status monitor program can show the current status of your printer. When printing, the animated dialog box appears on your computer screen to show the current printing process. If an error occurs, a dialog box will appear to let you know what to correct. For example: when your printer is out of paper, the dialog box will display "Paper Empty" and instructions for the proper corrective action.



Versatile Paper Handling The printer has a multi-purpose sheet feeder and straight paper path mechanism. Using this mechanism, you can load A4, letter, legal, B5, A5, and executive sizes of paper, and various types of paper including envelopes, postcards, organizer paper, or a custom paper size. The multi-purpose sheet feeder also allows manual paper loading, so you can use labels and transparencies. Environment-Friendly Economy Printing Mode This feature will save your printing cost by saving toner. It is useful to obtain draft copies for proof-reading. You can select from two economy modes, 25% toner saving and 50% toner saving, through the Windows printer driver supplied with your printer. Sleep Mode Sleep mode automatically reduces power consumption when the printer is not in use. The printer consumes less than 7W when in sleep mode. The time-out for auto sleep mode can be set through the Windows printer driver. Low Running Cost Since the toner cartridge is separate from the Drum Unit, you need to replace only the toner cartridge after around 2,200 pages printed, which is cost effective and ecologically friendly. Remote Printer Console Program for DOS The utility program, Remote Printer Console (RPC), is available on the floppy disk supplied with your printer. When you operate your computer in the DOS (Disk Operating System) environment, this program allows you to easily change the default settings of the printer such as fonts, page setup, emulations and so on. This program also provides a status monitor program, which is a Terminate-and-Stay Resident (TSR) program. It can monitor the printer status while running in the background and report the current status or errors on your computer screen. Popular Printer Emulation Support This printer supports three printer emulation modes, HP LaserJet IIP, Epson FX-850, and IBM Proprinter XL. When you use DOS application software or WindowsTM version 3.0 or earlier, you can use any of these emulations to operate the printer in the 300 dpi resolution mode. The printer also supports Auto-emulation switching between HP and Epson or HP and IBM. If you want to set the printer emulation, you can do it using the Remote Printer Console Program. Optional Apple Macintosh Interface The optional Apple Macintosh serial interface kit is available, which allows your printer to be connected to Apple Macintosh computers. With this option, you can use your printer with both an IBM PC, or compatible and an Apple Macintosh at the same time. This optional interface board can be used as an RS-422A interface for Macintosh or an RS-232C serial interface for IBM PC or compatible. Enhanced Memory Management The printer provides its own data compression technology on its printer hardware and the supplied printer driver software, which can automatically compress graphic data and font data efficiently into the printer's memory. You can avoid memory errors and print most full page 600 dpi graphic and text data, including large fonts, with the printer's standard memory.




3.1


Printing

Print method Resolution Print speed Electrophotography by semiconductor laser beam scanning 600 dots/inch (under Brother Printing Solution for Windows) 6 page/minute (when loading A4 or letter-size paper from the multipurpose sheet feeder) Max. 20 seconds at 23°C (73.4°F) 20 seconds (when loading A4 or letter-size paper from the multipurpose sheet feeder) Toner in a cartridge Life Expectancy: 2,200 pages/cartridge (when printing A4 or lettersize paper at 5% print coverage) Drum unit, separated from toner cartridge

Warm-up First print

Print media

Developer Print method Resolution

Electrophotography by semiconductor laser beam scanning 600 dots/inch (under Brother Printing Solution for Windows) 300 dots/inch (under DOS, Apple Macintosh and other operating system) 6 page/minute (when loading A4 or letter-size paper from the multipurpose sheet feeder) Max. 20 seconds at 23°C (73.4°F) 20 seconds (when loading A4 or letter-size paper from the multipurpose sheet feeder) Toner in a cartridge Life Expectancy: 2,200 pages/cartridge (when printing A4 or letter size paper at 5% print coverage) Drum unit, separated from toner cartridge

Print speed

Warm-up First print

Print media

Developer



3.2

Functions

CPU Emulation Printer driver Z80 12.5 MHZ Windows 3.1 GDI WindowsTM 3.1/3.11 and Windows 95 driver, supporting Brother Native Compression mode and bi-directional capability Bi-directional Centronics parallel interface. 0.5Mbytes Expandable up to 2.0 Mbytes with an optional memory board. MB-215W - 1.5 MB 1 switch and 4 lamps Self-diagnostic program

Interface Memory

Control panel Diagnostics CPU Emulation

MC68EC000 16 MHz Automatic emulation selection among HP LaserJet IIP, EPSON FX-850, and IBM Proprinter XL WindowsTM 3.1/3.11 and Windows 95 driver, supporting Brother Native Compression mode and bi-directional capability. Optional Macintosh® QuickDraw driver (Standard in some countries.) Bi-directional Centronics parallel interface. RS-422A/RS-232C serial interface is optionally available.(The serial interface is a standard in some countries.) 0.5 Mbytes (HL-730) or 1.0 Mbytes (HL-730Plus) only with Data Compression Technology. Expandable up to 2.0 Mbytes with an optional memory board. MB110 - 1.0 MB (for HL-730/730Plus) MB115 - 1.5 MB (for HL-730 only) 1 switch and 4 lamps Self-diagnostic program

Printer driver

Interface

Memory

Control panel Diagnostics



3.3

Electrical and Mechanical

Power source U.S.A. and Canada: Europe and Australia: Printing: Standing by: Sleep: Printing: Standing by: Operating: Storage: Operating: Storage: AC 110 to 120V, 50/60Hz AC 220 to 240V, 50Hz

Power consumption

150 W or less 35 W or less 7 W or less 48 dB A or less 35 dB A or less 10 to 32.5°C (59 to 90.5°F) 0 to 40°C (38 to 104°F) 20 to 80% (without condensation) 20 to 80% (without condensation)

Noise

Temperature

Humidity

Dimensions (W x D x H) 366 (W) x 353 (D) x 250 (H) (when the output tray is closed and the Multi-purpose sheet feeder is removed.) Weight Approx. 6.5 kg (14.3 lb.) including the drum unit

Power source U.S.A. and Canada: Europe and Australia: Printing: Standing by: Sleep: Printing: Standing by: Operating: Storage: Operating: Storage: AC 110 to 120 V, 50/60Hz AC 220 to 240 V, 50Hz

Power consumption

150 W or less 35 W or less 7 W or less 48 dB A or less 35 dB A or less 10 to 32.5°C (59 to 90.5°F) 0 to 40° C (38 to 104°F) 20 to 80% (without condensation) 20 to 80% (without condensation)

Noise

Temperature

Humidity

Dimensions (W x D x H) 366 (W) x 353 (D) x 250 (H) (when the output tray is closed and the Multi-purpose sheet feeder is removed.) Weight Approx. 6.5 kg (14.3 lb.) including the drum unit



3.4

Paper Specification (1) Multi-purpose tray loading Paper size: A4, Letter, Legal, B5, A5, and Executive, and other sizes of paper that can be handled by the feed mechanism, can be loaded.

90 to 229 mm

148 to 356 mm (face down)

Feeding direction

Feedable paper type: Maximum load height: Envelopes: Setting method:

60 (16 lb.) to 157 (42 lb.) g/m2 (long-grained paper) 22 mm (200 sheets of 75 g/m2 paper) letter size 10 envelopes Pull the manual paper tray toward you, insert the sheet of paper into the tray, aligning the top edge of the sheets, then push the tray back to its original position.

(2) Manual paper loading The manual paper loading takes priority of feeding and a single sheet of paper can be fedinto the printer. The applicable sizes and types of paper are the same as the multi-purpose tray loading above in specification. 3.5 Print Delivery (1) At the print delivery tray opened Tray capacity : Maximum 100 sheets (75g/m2), face-down only (2) At the print delivery tray closed Tray capacity : 1 sheet (75 g/m2), face-down only

Note)
3.6 Paper

Face down: Environment :

Deliver the printed face of the paper downward. 23°C

(1) Types of paper (a) Normal paper (60 to 157 g/m2, specified types of high-quality paper) · · · · · · · A4 size Letter size Legal size B5 size A5 size Executive size 9" envelop size (printing face is Letter size)

*The specified types of plain paper are as follows: Letter : Xerox 4200 (75 g/m2) A4 : Xerox 80 Premier Paper



(b)

Special paper (specified types) · · · · Labels Envelopes (DL,C5, COM10) Postcards Organizers (K, L, and J sizes of DAY-TIMERS)

(2) Paper feed conditions Types Normal paper (cut sheet) Special paper (cut sheet) Name 60 to 157 g/m paper Labels Envelopes Postcards Organizers
2

Tray feed

Manual feed





3.7

Effective Printing Area Printable area

E

A C E

F

B

D

F
The effective printing area means the area within which the printing of all the data received without any omissions can be guaranteed.




The table below shows the effective printing areas. Size A4 A 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) 184.15mm 7.25" (2,175 dots) 148.5mm 5.85" (1,754 dots) 69.85mm 2.75" (825 dots) 95.25mm 3.75" (1,125 dots) 139.7mm 5.5" (1,650 dots) 104.78mm 4.125" (1,237 dots) 98.43mm 3.875" (1,162 dots) 162mm 6.38" (1,913 dots) 110mm 4.33" (1,299 dots) B 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) 210.0mm 8.27" (2,480 dots) 127.0mm 5.0" (1,500 dots) 171.45mm 6.75" (2,025 dots) 215.9mm 8.5" (2,550 dots) 241.3mm 9.5" (2,850 dots) 190.5mm 7.5" (2,250 dots) 229mm 9.01" (2,704 dots) 220mm 8.66" (2,598 dots) C 203.2mm 8.0" (2,400 dots) 203.2mm 8.0" (2,400 dots) 203.2mm 8.0" (2,400 dots) 170.0mm 6.69" (2,007 dots) 164.0mm 6.46" (1,936 dots) 175.7mm 6.92" (2,075 dots) 135.8mm 5.35" (1,604 dots) 56.2mm 2.21" (663 dots) 86.78mm 3.42" (1,024 dots) 131.23mm 5.17" (1,550 dots) 92.11mm 3.63" (1,087 dots) 85.7mm 3.37" (1,012 dots) 150.0mm 5.9" (1,771 dots) 98.0mm 3.86" (1,157 dots) D 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) 201.5mm 7.93" (2,380 dots) 118.5mm 4.66" (1,400 dots) 163.0mm 6.42" (1,925 dots) 207.43mm 8.17" (2,450 dots) 232.8mm 9.16" (2,750 dots) 182.0mm 7.16" (2,150 dots) 220.5mm 8.68" (2,604 dots) 211.5mm 8.33" (2,498 dots) E 3.4mm 0.13" (40 dots) 6.35mm 0.25" (75 dots) F 4.23mm 0.17" (50 dots)

Letter



Legal


6.01mm 0.24" (71 dots)

B 5 (JIS)

B 5 (ISO)


6.35mm 0.25" (75 dots) 6.01mm 0.24" (71 dots) 6.35mm 0.25" (75 dots)

Executive

A5 Organizer (J size) Organizer (K size) Organizer (L size)


6.01mm 0.24" (71 dots)

COM-10

MONARCH

C5

DL



(Note that the paper sizes indicated here should conform to the nominal dimensions specified by JIS.) A4 paper must accommodate 80 characters printed in pica pitch (203.2 mm). The dot size is based on 300 dpi resolution.




4.1


Laser Safety (110 - 120V Model only) This printer is certified as a Class 1 laser product under the US 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 dose not produce hazardous laser radiation. Since radiation emitted inside the printer is completely confined within the protective housings and external covers, the laser beam cannot escape from the machine during any phase of user operation.

4.2

CDRH Regulations (110 -120V Model only) The Center for Device and Radiological Health (CDRH) of the US Food and Drug Administration implemented regulations for laser products on August 2, 1976. These regulations apply to laser products manufactured from August 1, 1976. Compliance is mandatory for products marketed in the United States. The label shown below indicates compliance with the CDRH regulations and must be attached to laser products marketed in the United States. The label for Japanese products

MANUFACTURED : BROTHER INDUSTRIES, LTD. 15-1, Naeshiro-cho, Mizuho-ku, Nagoya 467, Japan. This product complies with FDA radiation performance standards, 21 CFR Subchapter J.

K

The label for Chinese products

MANUFACTURED : C Brother Corporation (Asia) Ltd.. Shenzhen Buji Nan Ling Factory Gold Garden Ind., Nan Ling Village, Buji, Rong Gang, Shenzhen, CHINA. This product complies with FDA radiation performance standards, 21 CFR Subchapter J.



4.3

Caution for Laser Product (1) CAUTION: When the machine during serving is operated with open cover, the regulations of VBG 93 and the performance instructions for VBG 93 are valid. In case of any trouble with the laser unit, please replace the laser unit itself. To prevent direct exposure to the laser beam, do not try to open the enclosure of laser unit.

(2) CAUTION:

(3) Location of the Exit Opening of Laser Beam.




Fig. 1.2 (4) Location of Caution Label for Laser Product.

Fig. 1.3



CHAPTERII THEORY OF OPERATION
1.
1.1

ELECTRONICS
General Block Diagram Fig. 2.1 shows a general block diagram of this printer.
Optional RAM board (1.5, 3.5 Mbytes)

Control system Expansion memory I/O

Low-voltage power supply block

Interface block Video control block

Engine control block Operation block (Operation panel) Erase lamp
High-voltage power supply block

Laser scanner unit

Drive block (Stepping motor)

Paper tray unit Paper tray Manual feed

Drum unit Transfer block

Fixing unit Developing block Charging block Drum Cleaner block

Paper eject block

Paper feed system Toner cartridge Image generation system

Fig. 2.1

II-1

External device

Fig. 2.2 shows a general block diagram of this printer.

Optional RAM board (1.0, 1.5 Mbytes)

Optional I/F board (Mac. RS-232C)

Control system Expansion memory I/O Expansion I/O

Low-voltage power supply block

Interface block Video control block

Engine control block

Operation block (Operation panel) Erase lamp

High-voltage power supply block

Laser scanner unit

Drive block (Stepping motor)

Paper tray unit Paper tray

Drum unit Transfer block

Manual feed

Fixing unit Developing block Charging block Drum Cleaner block

Paper eject block

Paper feed system Toner cartridge

Image generation system

Fig. 2.2

II-2

External device

External device

1.2

Main PCB Block Diagram Fig. 2.3 shows a block diagram of the main PCB.
ASIC

Reset Circuit

CPU Core (Z80) BUS INT

Oscillator (12.27 MHz)

Program ROM 16 Kbytes DRAM 0.5 Mbytes DRAM Control

Working S-RAM 512 Bytes Option RAM 1.5 Mbytes or 3.5 Mbytes Timer

CDCC Parallel I/O

To PC

DATA Extension

FIFO

EEPROM (128 x 8 bits)

EEPROM I/O

Motor Driver

Engine Control I/O

To Panel sensor PCB

Fig. 2.3

II-3

Fig. 2.4 shows a block diagram of the main PCB.
A S I C CPU Core Reset Circuit (MC68EC000) BUS INT Oscillator (15.3MHz)

Address Decoder Program + Font ROM 512 Kbytes DRAM Control

Timer RAM (0.5 Mbytes) FIFO

Option RAM (1M or 1.5Mbytes) DATA EXTENSION

CDCC Parallel I/O Option Serial I/O (RS232C & RS422A) Soft Support

To PC

EEPROM (128

8 bits)

EEPROM I/O

Motor Driver

Engine Control I/O

To Panel Sensor PCB

Fig. 2.4

II-4

1.3

Main PCB 1.3.1 CPU Core

Fig. 2.5 shows the ASIC circuit block on the main PCB. The CPU core is a Z80 which is driven with a clock frequency of 12.27 MHz. This frequency is made by dividing the source clock of 24.54 MHz into two in the oscillator circuit. The address bus is 16 bits and the data bus is 8 bits. The total memory space is 64 Kbytes. The CPU core access directly only the program ROM and the working S-RAM, and the DRAM through the DRAM control unit.

NOTE:

The ASIC has the functions above.

Fig. 2.5

II-5

Fig. 2.6. shows the CPU circuit block on the main PCB. The CPU is a Motorola MC68EC000FN16 which is driven with a clock frequency of 15.3 MHz. This clock frequency is made by dividing the source clock of 30.67 MHz into two. The address bus is 23 bits of A1 to A23, and the data bus is 16 bits. The total memory space is 16 Mbytes.

Fig. 2.6

II-6

1.3.2

ASIC

The ASIC is composed of Cell Based IC and has the following function blocks. (1) Oscillator circuit Oscillator circuit drives the outside ceramic resonator, and generates the main clock for the CPU core by dividing the source clock frequency into two. It is also equipped with the several clocks for timer unit, engine control I/O unit, CDCC parallel I/O unit, data extension unit and FIFO. (2) Program ROM The program ROM of 16 Kbytes is contained in this ASIC. (3) Working S-RAM The working S-RAM of 512 Bytes is also contained in this ASIC as a work RAM for the CPU core. (4) DRAM control circuit This circuit generates the RAS, CAS, WE, OE and MA signals for the DRAM and controls the refresh for the DRAM (CAS before RAS self-refreshing method). The CPU core, the CDCC parallel I/O unit and the data extension unit access the DRAM through the DRAM bus controlled by the DRAM control unit. (5) Interrupt control This circuit controls all the interrupts to the CPU core. The CPU core has no priority to each interrupt element. If the first interrupt is accepted, then the second waits until the first has been complete. The interrupt elements can be masked respectively. (6) Timers The following timers are incorporated: Timer 1 16-bit timer Timer 2 10-bit timer Timer 3 Watch-dog timer

II-7

(7) CDCC parallel I/O There are two modes in this unit. One is the CPU receiving mode and the other is the DMA receiving mode. In the CPU receiving mode the CPU receives the command data from the PC, and after the CPU is switched to the DMA mode, it receives the image data and writes to the DRAM directly. CPU Receiving Mode

STROBE

BUSY ACK 90 µsec 0.5 µsec

STROBE

BUSY ACK 1.5 µsec 0.5 µsec

BUSY goes HIGH at the falling edge of STROBE. The data (8 bits) from the PC is latched in the data buffer at the rising edge of STROBE. The pulse width of ACK differs according to the speed MODE as shown above. BUSY goes LOW at the rising edge of ACK. This supports the IEEE1284 data transfer with the following mode. Nibble mode Byte mode (8) Data extension This circuit extents the compressed image data which are received from the PC, and writes the bit map data to the FIFO. (9) FIFO A 5,120-bit FIFO is incorporated. Data for one raster is transferred from DRAM to the FIFO through the data extension unit and exported as the serial video data. The data cycle is 6.13 MHz. (10)EEPROM I/O One output port and one I/O port are assigned.

II-8

(11) Engine control I/O This I/O is used for the connection to the panel sensor PCB. It controls the main motor, solenoid, sensors, scanner, etc.

II-9

The ASIC is composed of Cell Based IC and has the following function blocks. (1) Oscillator circuit Generates the main clock for the CPU by dividing the source clock frequency into two. (2) Address decoder Generates the CS for each device. (3) DRAM control Generates the RAS, CAS, WE, OE and MA signals for the DRAM and controls refresh recessing (CAS before RAS self-refreshing method). (4) Interrupt control Interrupt levels: Priority High 7 6 5 4 3 2 1 NMI FIFO EXINT(Option Serial I/O) BD / Timer 1 SCANINT CDCC / BOISE / DATA EXTENTION Timer 2

Low (5) Timers

The following timers are incorporated: Timer 1 Timer 2 Timer 3 (6) FIFO A 5,120-bit FIFO is incorporated. Data for one raster is transferred from the RAM to the FIFO by DMA transmission and is output as serial video data. The data cycle is 6.13 MHz. 16-bit timer 10-bit timer Watch-dog timer

II-10

(7) CDCC parallel I/O There are two modes in this unit. One is the CPU receiving mode and the other is the DMA receiving mode. In the CPU receiving mode the CPU receives the command data from the PC, and after the CPU is switched to the DMA mode, it receives the image data and writes to the DRAM directly. CPU Receiving Mode
STROBE

BUSY ACK 90 µsec 0.5 µsec

STROBE

BUSY ACK 1.5 µsec 0.5 µsec

BUSY goes HIGH at the falling edge of STROBE. The data (8 bits) from the PC is latched in the data buffer at the rising edge of STROBE. The pulse width of ACK differs according to the speed MODE as shown above. BUSY goes LOW at the rising edge of ACK. This supports the IEEE1284 data transfer with the following mode. Nibble mode Byte mode (8) Data extension This circuit extents the compressed image data which are received from the PC, and writes the bit map data to the FIFO. (9) Software support Supports 16 x 16 rotation, bit expansion, and bit search. (10)EEPROM I/O One output port and one I/O port are assigned.

II-11

(11)Engine control I/O This I/O is used for the connection to the panel sensor PCB. It controls the main motor, solenoid, sensors, etc.

Fig. 2.8

II-12

1.3.3

ROM

A program of 512 Kbytes and the font data are stored in the ROM. A 42-pin IC socket is provided: an 8 Mbits ROM (42-pin) can be mounted to this socket normally, but a 4 Mbits ROM (40-pin) must be mounted to leave the 1st and 42nd pins of the socket opened.

Fig. 2.9 1.3.4 DRAM

A 4M-bit DRAM (x8 bits) is used as the RAM.

Fig. 2.10

II-13

A 4M-bit DRAM (x 16bits) is used as the RAM. Only one DRAM is installed in the 0.5 Mbyte model.

Fig. 2.11

II-14

1.3.5

Optional RAM

Three 4M-bit DRAM (x 8 bits) and one 16M-bit DRAM (x 8 bits) are used as the optional RAM. The total memory area is expanded up to 4 Mbytes.

Fig. 2.12 There are two types of optional RAMs: the 1 Mbyte model and the 1.5 Mbytes model for HL-730, and one type of optional RAM: the 1Mbyte model for HL730Plus. The memory capacity can be expanded up to 2 Mbytes for both HL-730 and HL-730Plus. HL-730 (0.5 M model): + 1 M optional RAM = 1.5 Mbytes + 1.5 M optional RAM = 2 Mbytes HL-730Plus (1 M model) + 1 M optional RAM = 2 Mbytes

Fig. 2.13

II-15

1.3.6

Optional Serial I/O

The interrupt of serial I/O are input to the EXINT terminal of the ASIC, and are recognized by the CPU. A 32-byte space for register is provided for this I/O, which are read and written to by the CPU.

Fig. 2.14 1.3.7 EEPROM

The EEPROM is XL24C01AF type of a two-wire method with a 128 x 8 bits configuration.

Fig. 2.15 The EEPROM is XL24C01AF type of a two-wire method with a 128 x 8 bits configuration.

Fig. 2.16

II-16

1.3.8

Reset Circuit

The reset IC is PST591DMT. The reset voltage is 4.2V (typ.) and the LOW period of reset is 50 ms (typ.).

Fig. 2.17

The reset IC is PST593DMT. The reset voltage is 4.2V (typ.) and the LOW period of reset is 200 ms (typ).

Fig. 2.18

II-17

1.3.9

CDCC I/O

Fig. 2.19 shows the CDCC interface circuit.

Fig. 2.19 Fig. 2.20 shows the CDCC interface circuit.

Fig. 2.20

II-18

1.3.10

Engine I/O

Fig. 2.21 shows the engine interface circuit.

Fig. 2.21

II-19

Fig. 2.22 shows the engine interface circuit.

Fig. 2.22

II-20

1.3.11

Paper Feed Motor Drive Circuit

The motor driver consists of a TR array. The excitation method is 2-2 phase excitation with an bipolar drive.

Fig. 2.23 The motor driver is a TR array, The excitation method is 2-2 phase excitation with an bipolar drive.

Fig. 2.24

II-21

1.4

Panel Sensor PCB The following parts are on the panel sensor. · Operation Panel .......1Key, 4LEDs · Connector..................Low-voltage, high-voltage, solenoid, main motor, toner sensor, laser, polygon motor, connector for main PCB · Registration sensor

II-22

1.5

Power Supply The power supply uses the switching regulation system to generate the regulated DC power (+5V and +24V), which are converted from the AC line.

(Heater)
Thermal Fuse Heater Circuit Lamp

Fuse

Lightning Surge Absorber

Feedback

Line Filter

Rectifier

Oscillator

(Panel Sensor Circuit)

24V Regulation Circuit

24V

5V Regulation Circuit

5V

Fig. 2.25

II-23

2.
2.1

MECHANICS
Overview of printing mechanism
Multi-Purpose Sheet Feeder Manual Paper Pass Paper Supply Unit Papers

Paper Pick-up Roller Paper Feed Roller Drum Unit

Pitch Roller Auger Hopper Plate Blade

Photosensitive Drum Transfer Roller Erase Lamp

Fuser Unit Pressure Roller Eject Sensor Actuator Eject Roller

Registration Sensor Lever Toner Cartridge

Polygon Mirror

Heat Roller

Laser Scanner

Toner Empty Sensor

Developer Roller Cleaner Roller Primary Charger

Supply Roller

Fig. 2.26
Scanner Unit Main Motor Fan Motor Registration Sensor PCB HighVoltage Power Supply Registration Sensor Solenoid Charger

Primary Charger (Corona Wire) Primary Charger (Grid) Developer Roller Transfer Roller Paper Eject Sensor Thermistor

Main PCB

Panel Sensor PCB

Paper Eject Sensor PCB Toner Empty Sensor PCB

Toner Empty Sensor

II-24

2.2

Paper Transfer 2.2.1 Paper Supply The pick-up roller picks up one sheet of paper from the paper tray at every one rotation and feeds it to the paper feed roller one by one.
Papers Pick-up roller

Registration sensor lever

Hopper plate

Separation pad

Fig. 2.27 The paper is gripped between the pick-up roller and the separation pad and separated into individual sheets. The pick-up roller is directly connected to the sector gear, whose rotation is forcibly stopped by the gear stopper; when the pick-up solenoid is activated, the clutch mechanism is engaged by the solenoid ON/OFF and the sector gear is driven; when it has completed one full turn its rotation is stopped again by the gear stopper. The paper drawn out by the pick-up roller presses against the top of form sensor lever and the paper top position/absence of paper is detected by sensing the motion of the lever. 2.2.2 Paper Registration When paper picked up from the multi-purpose paper tray (MPT) presses against the top of form sensor actuator, the registration sensor lever is caused to turn, and the photo sensor detects this motion. With this signal from the sensor the paper feed roller is stopped of its rotation temporarily by the clutch. Then paper is fed to the nip point between the paper feed roller and the pinch roller in the multi purpose paper tray, and the skew of the paper is corrected by the bump of the leading edge of paper against the nip point. When the paper feed roller starts to rotated again by the motion of clutch, paper, leading edge of which has been aligned, is fed by the paper feed roller and is transported to the transfer roller.
Paper Paper feed roller Pinch roller Transfer roller Idle gear Paper feed gear

Paper feed roller Drum

Clutch mechanism (engaged/released by the solenoid assembly) Released when the solenoid is ON and engaged when the solenoid is OFF.

Fig. 2.28

II-25

2.2.3

Paper Eject The completion of paper eject is detected in the following manner: (a) When the leading edge of the paper push down the eject sensor actuator located in the fixing unit, the photo sensor (photo interrupter) is opened and detects the start of paper eject motion. After that, when the bottom of the edge of paper has passed through the paper eject sensor actuator, the photo sensor is closed and the completion of paper eject motion is recognized.
Transfer roller

(b)


Pressure roller

Eject sensor actuator Eject roller

Drum Heat roller

Eject sensor actuator

Paper

Paper

High-voltage power supply PCB

, ,
Sensor Sensor

Fig. 2.29

II-26

2.3

Sensors 2.3.1 Cover Sensor Detects open or close of the top cover. Toner Empty Sensor Detects if there is toner in the toner cartridge. It also detects whether or not the drum unit is installed. (The toner cartridge is installed in the drum unit).

2.3.2

Top Cover

Cover Switch

Fig. 2.30

II-27

2.4

Drum Unit 2.4.1 Photosensitive Drum Generates the latent electrostatic image and develops the image on the drum surface. 2.4.2 Primary Charger Forms a uniform charge on the drum surface. (1) (2) 2.4.3 Corona wire Generates ion on the drum. Grid Spreads the ion evenly over the drum. Developer Roller Develops the latent electrostatic image on the drum surface by the toner. 2.4.4 Transfer Roller Transfers the toner image to the paper from the drum surface. 2.4.5 Cleaner Roller Removes and exhausts the toner remaining on the drum surface. 2.4.6 Erase lamp Discharges the electrostatic latent image on the drum.

2.5

Print Process 2.5.1 Charging The drum is charged to approx. +1000V by ion which is generated by the primary charger. Ion is generated by an ionization of the corona wire, which applied DC bias from High-voltage Power Supply. The flow of ion is controlled by the grid to be distributed evenly on the drum surface. The other end of the grid is generated to approx. 280V by the voltage regulator.
280V Passive Type Voltage Regulator

Voltage Regulator

+ + + -- + ++ - - - ++ + + 1000V + + + + + + + + + ++

-

Aluminum pipe Grid Organic Photoconductor layer

Drum

HVPS Corona wire

Fig. 2.31 The primary charge uses a corona wire, but since the charging terminal of the drum is a positive terminal , only less than 1/10 of the usual quantity of ozone is generated. The level of ozone expelled from the printer is therefore not harmful to the human body. Applicable safety standards have been complied with.

II-28

2.5.2

Exposure stage After the drum is positively charged, it is exposed to the light emitted from the laser unit.
Drum Laser Beam Paper Laser beam f lens Polygon mirror Motor Laser diode Lens

Laser detector

Fig. 2.32 The exposed area is the part to be printed. The surface potential of the exposed area is recreated forming an electrostatic image to be printed.
1 Cycle of drum 1 4 2 Primary charging Laser beam exposure and developing (a) Unexposed area ( Non image area ) (b) Exposed area ( Image area ) Transfer the image to paper Erase the residual potential

Surface Potential (V)

1 +1000 +700

2 (a)

3

3 (b) 4

+400 Drum +300 Sleeve Time

Fig. 2.33

II-29

2.5.3

Developing Developing causes the toner to be attracted to the electrostatic image on the drum so as to transform it into a visible image. The Developer Consists of the non-magnetic toner. The developer roller made of conductive rubber and the supply roller made of conductive sponge rotate on each other. The toner is charged and carried from the supply roller to the developer roller. Thus, the toner is adhered to the developer roller and conveyed to the drum with its thickness made even by the blade. The toner is nipped between the developer roller and the drum and developed on the latent image. Electrostatic field between the drum and the developer roller, which is DC-biased from the High-voltage power supply, makes electrostatic potential to attract toner particles from the devel oper roller to the drum.
Transfer roller Blade Toner (b) Cleaning process [ON] Auger (a) Transfer process [ON]

Erase lamp Develop housing

Drum Supply roller DC-bias Developer roller Cleaner roller

Fig. 2.34 2.5.4 Transfer (a) Transfer process After the drum has been charged and exposed , and has received a developed image, the toner formed image is transferred onto the paper, applying the negative charge from the backside of the paper. The negative charge to the paper causes the positive charged toner to leave the drum, and adhere to the paper. As a result, the image is visible on the paper. (b) Cleaning process of transfer roller If the toner is not transferred onto the paper perfectly due to jamming etc., it is possible that the toner adheres to the charge transfer roller. The transfer voltage charges to positive voltage during non transferring process. Therefore the transfer roller is cleaned by returning the positive charged toner adhered on the transfer roller onto the photo-conductive drum.

II-30

2.5.5

Drum Cleaning Stage In the image transfer stage, not all the toner on the photosensitive drum is transferred onto the paper but some of them remain on the drum. In the drum cleaning stage, the drum surface is cleaned by the cleaning roller, so that residual toner on the drum surface is removed away and collected in the cleaning roller itself. The residual toner in the cleaning roller will be discharged to the drum when starting or unprinting the toner will be collected by a developing roller and reused (for further developing).

2.5.6

Erasing Stage Before the cleaning stage, the drum surface is exposed by the light emitted from the erase lamp. (LED lamp) This stage prepares the drum to decrease its surface voltage uniformly, and to receive an uniform change in the primary changing stage.

II-31

CHAPTERIII








To prevent the creation of secondary problems by mishandling, be careful about the following precautions during maintenance work. (1) Always turn off the power switch and unplug the power cord from the power outlet before accessing any parts inside the printer. (2) Be careful not to lose screws, washers, or other parts removed. (3) Be sure to apply grease to the gears and applicable positions specified in this chapter. (4) When using soldering irons or other heat-generating tools, take care not to damage the resin parts such as wires, PCBs, and covers. (5) Before handing the PCBs, touch a metal portion of the equipment to discharge the static electricity charged in your body, or the electronic parts or components may be damaged. (6) When transporting PCBs, be sure to wrap them in conductive sheet such as aluminum foil. (7) Be sure to replace self-tapping screws correctly, if removed. Unless otherwise specified, tighten screws to the following torque values. TAPTITE, BIND or CUP B M3 : 6kgf · cm M4 : 9kgf · cm TAPTITE, BIND S M3 : 9kgf · cm SCREW M3 : 7kgf · cm M4 : 10kgf · cm (8) When connecting or disconnecting cable connectors, hold the connector bodies, but not the cables. If the connector has a lock, release the connector lock first to unlock it. (9) After a repair, check not only the repaired portion but also the connectors, or check if other related portions are functioning properly before doing operation checks.





BOTTOM
1 DRUM UNIT 6



MAIN PCB ASSY

B B
7 2 TOP COVER BASE PLATE ASSY

A
8 3 MP PAPER TRAY ASSY PANEL SENSOR PCB ASSY 9 LOW-VOLTAGE PS PCB ASSY 10 HIGH-VOLTAGE PS PCB ASSY

4

C
FIXING UNIT 12 DRIVE UNIT

11

FAN MOTOR

C
5 SCANNER UNIT 13 MAIN MOTOR ASSY and MOTOR HEAT SINK



A

15 16

TRAY EXTENSION PAPER EJECT TRAY ASSY

14

GEARS and SOLENOID


3.1




Drum Unit (1) Open the top cover. (2) Lift out the drum unit.







Fig. 3.1 3.2 Top Cover (1) Open the top cover to the first lock position. (2) Prize up the top cover link and free it from the dowel on the top cover to release it inward. (3) Press the link downward.















Fig. 3.2



(4) Open the top cover further, release the catch of the both side by sliding the top cover backward.






Fig. 3.3 3.3 Multi-purpose Paper Tray Assy (1) Tilt the left outward and pull out the MP tray. It is not necessary to tilt the right rib.

!









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!"#! $(()*



%+,

,

Fig. 3.4

NOTE: When reassembling, apply a suitable amount of grease (2 rice-grain size) between the heat sink of the motor and the ground leaf spring in case of grease shortage.



PR98292 3.4 Fixing Unit (1) Remove the M4x12 screw securing the fixing unit. (2) Lifting up the fixing unit, disconnect the two heater harnesses and remove the connector of thermistor on EL PCB.

-

2 )-3, . '/
* . '/*


'0* $! 1/
Fig. 3.5 (3) Remove the two M3x10 screws. (4) Open the fixing unit cover along the open side of the fixing unit cover.

-
2 (-35 4 -
1


-
Fig. 3.5a



(5) Release the right side of the paper eject roller shaft. (6) Remove the four eject pinch rollers and the pinch springs from the fixing unit frame. Then, remove the pinch spring from each pinch roller.

1 6


1 4 $6 1


Fig. 3.5b (7) Remove the M3x10 screw securing the electrode plate to remove the electrode plate from the fixing unit frame. (8) Loosen the other M3x10 screw securing the fixing unit cover. (9) Remove the heat roller. Then, remove the halogen heater lamp from the heat roller.

Caution: Never touch the surface of the halogen heater lamp and the heat roller.

.
.
'/ 35572 ,557* (-35 (-35

$


Fig. 3.5c



3.5

Scanner Unit (1) Remove the three screws. (2) Lift out the scanner unit. (3) Disconnect the three connectors of the scanner unit from the panel sensor PCB. (4) Remove the screw and disassemble the Toner sensor PCB from the Scanner unit.




1/

'132 1,2 1(* 4 1
1/

Fig. 3.6

NOTE: Never touch the inside of the scanner unit or the mirror when disassembling or reassembling. If there is any garbage or dust on the mirror, blow it off.
3.6 Main PCB Assy (1) Remove three screws securing the main PCB holder on the back side of the printer. (2) Grasp the hooks at left and right and draw out the main PCB assy.



1/

.

#8 4

4
Fig. 3.7

.





3.7

Base Plate Assy

NOTE Prior to turning the printer upside-down, drum unit should be removed from the printer.
(1) Turn the printer upside down. (2) Remove the four M4 and four M3 tapping screws. (3) Lift out the base plate assy and remove the grounding screw.

( 4 '4 * ) 4 '/ *

( 4 '4 * ) 4 '/ *


0
/





Fig. 3.8 3.8 Panel sensor PCB Assy (1) Remove the screw securing the panel sensor PCB assy. (Remove the part A from under the main shield) (2) Disconnect the seven connectors from the PCB (The three connectors have already disconnected at the disassembling scanner unit. See page, III-5 ).

1
1/

9

4 4

'1%* .7 '1&* !7 '1)* '*

'1:*
Fig. 3.9




NOTE1:When reassembling, the connectors must be inserted to the PCB without floating and the PCB must not be floated by the harnesses. NOTE2:The connector should be inserted by fitting the housing color and the pin number.
3.9 Low-Voltage Power Supply PCB Assy (1) Remove the screw securing the low-voltage power supply PCB assy. (2) Disconnect the two connectors from the component side of the PCB.

!


1/ . ';3*

!7 ';353*
Fig. 3.10 3.10 High-voltage Power Supply PCB Assy (1) Remove the screw securing the high-voltage power supply PCB assy. (2) Disconnect the four connectors from the PCB.

#
.

1/
1/ '1)*



'1,*

'1(* .7 '13*
Fig. 3.11




NOTE: When reassembling, the density volume must be fitted into the cut side of the density dial.



3.11

Fan Motor (1) Disconnect the connector from the high-voltage power supply PCB. ( It has been disconnected already. See above) (2) Take off the fan motor assy.





Fig. 3.12 3.12 Drive Unit (1) Remove the four screws securing the drive unit.


Fig. 3.13



3.13

Main Motor Assy and Motor Heat Sink (1) Remove the two screws securing the main motor assy. (2) Remove the two screws securing the motor heat sink.








Fig. 3.14 3.14 Gears and Solenoid (1) Apply grease the point as shown below. Grease: MOLYKOTE EM-30L TKC-0 MOLYKOTE EM-D110

9

'$335* ,58<) )58#
:) ):
4

1


,5

(5 3)8)& ! '$(5!*

NOTE: Apply EM-30L to the small gears (2 pcs.) inside "Gear 45 arm assy".
Fig. 3.15



3.15

Tray Extension (1) Put the tray extension assy down toward the front of the printer, and pull the bottom of its both side legs outward to release it.

-







Fig. 3.16 3.16 Paper Eject Tray Assy (1) Open the paper eject tray. (2) Press the both sides of hinges of the paper eject tray inward to release it from the holes on the top cover. (3) Press the tray extension toward the arrays and remove it.





1 6

-


Fig. 3.17







;








2 4




1

1

1




Fig. 3.18



CHAPTERIV TROUBLESHOOTING
1.
1.1

INTRODUCTION
Initial Check (1) Operating environment

Check if : 1) The source voltage stays within ±10% from the rating voltage shown on the rating plate. 2) The printer is installed on a solid, level surface. 3) The room temperature is maintained between 10°C and 32.5°C. The relative humidity is maintained between 20% and 80%. 4) The printer is not exposed to ammonia fumes or other harmful gases. 5) The printer is not located in a hot or humid area (such as near water or a humidifier) 6) The printer is not exposed to direct sunlight. 7) The room is well-ventilated (2) Printer paper Check if : 1) A recommended type of print paper is being used (if the paper is too thick or too thin, or tends to curl, paper jams or paper feed problems may occur, or prints may be blurred). 2) The print paper is damped. [If so, use fresh paper, and check whether the print quality improves or not.] (3) Consumables Check if : 1) The toner LED is not lit on the display when a toner cartridge is installed in the printer. [If the above LED is lit, replace the cartridge with a new one. If blank spots occur on prints, take out the process cartridge and slowly rock it to distribute the toner evenly.] (4) Others Condensation: When the printer is moved from a cold room into a warm room in cold weather, condensation may occur inside the printer, causing various problems as below: 1) Condensation on the optical surface such as the scanning mirror, lenses, the reflection mirror and the protection glass may raise/cause the print image to be light. 2) If the photosensitive drum is cold, the electrical resistance of the photosensitive layer gets high, making it impossible to obtain a correct contrast in printing. 3) Condensation on the corona unit may cause corona leakage. 4) Condensation on the hopper gate and separation pad may cause paper feed troubles. If condensation has occurred, wipe the effected units or parts with a dry cloth.



If the process cartridge is unsealed soon after moved from a cold room to a warm room, condensation may occur inside the cartridge, which may cause incorrect image. Instruct the user to allow the cartridge to come to room temperature before unsealing it. This will take one to two hours.

1.2

Basic Procedure If a malfunction or incorrect print is appeared, make an initial check, then follow the basic procedure below: (1) Check the error lamps according to the procedure of inspection mode described on the later pages of this section. If no error lamp is lit, see Section 4 for troubleshooting. (2) If any incorrect image is found, follow the image defect description in this section.



2.
2.1

IMAGE DEFECTS
Image Defect Examples

I-1 Light

I-2 Dark

I-3 Completely blank

I-4 All black

I-5 Dirt back of paper

I-6 Black vertical streaks

I-6 Black and blurred vertical stripes

I-7 Black and blurred horizontal stripes

I-8 Dropout

I-9 White vertical streaks

I-10 Faulty registration

I-11 Poor fixing

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