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Service Guide ML520/521
Chapter 0 About This Manual
ML520 // ML521 Dot Matrix Printers
Adobe Acrobat printable reference copy of the OKIDATA Service Training Manual. 09/17/97
Note: This Adobe Acrobat version of the Okidata Service Training Manual was built with the pictures rendered at 300 dpi, which is ideal for printing, but does not view on most displays well.
Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)
Table of Contents
Page
Service Guide ML520/521
0 About This Manual Front Cover Copyright Information 1 Product Specifications 1.1.01 General Information ....1.2 Physical Specifications ....1.3 Power Requirements ....1.4 Environmental Conditions ....1.5 Agency Approvals ....1.6 Operational Specifications ....1.7 Paper Specifications ....1.8 Memory Specifications ....1.9 Consumables ....1.10 Options - Cut Sheet Feeders ........1.10.02 Pull Tractor Kit ........1.10.04 Bottom Push Tractor Kit ........1.10.05 Serial Interface ........1.10.06 Roll Paper Stand ........1.10.08 OKISmart Typer Utility ....1.11 Reliability 2 Principles of Operation 2.1 Electrical Operation ....2.1.01 Main Control Board ........Block Diagram ........Program ROM ........RAM ........LSI ........Electrically Erasable Programmable Read Only Memory (EEPROM) ....2.1.02 Initialization ....2.1.03 Parallel Interface Control ....2.1.04 Print Control ........LSI/Printhead Interface ........Gap Adjust Control ........Print Compensation Control ....2.1.05 Space and Line Feed (SP/LF) Motor Control ........Line Feed Motor Control ........Space Motor Control ........Encoder Disk ....2.1.06 Operation Panel ....2.1.07 Alarm Circuit ........Low Motor Drive Voltage Alarm 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38
Table of Contents ........Head Drive Time ........Print Speed ........%Head Overheat Alarm Processing ....2.1.08 Power Supply Circuit 2.2 Mechanical Operation - Printhead Mechanism ........Printhead Gap Information ........Interconnect Diagram: Control Board to Printhead ........Line Feed Motor Resistance ........Space Motor Resistance ........Printhead Operation ........Printhead Temperature ....2.2.02 Spacing Mechanism ........Spacing Operation ....2.2.03 Head Gap Mechanism ........Ribbon Drive Operation ....2.2.05 Line Feed Mechanism ........Cut Sheet/Continuous Sheet Switching Mechanism ........Cut Sheet Paper Feed Operation ........Continuous Paper Feed (Rear Tractor Mechanism) ........Continuous Paper Feed (Pull Tractor Mechanism) ........Continuous Paper Feed (Bottom Tractor Feed Mechanism) ........Continuous Paper Feed (Push/Pull Tractor Mechanism) ....2.2.06 Paper Detection Mechanism ....2.2.07 Support Protector Mechanism ....2.2.08 Automatic Paper Load ........Continuous Feed Paper ....2.2.09 Paper Park 3 Maintenance & Disassembly ....3.1.01 General Information ....3.1.02 Maintenance Tools ....3.1.03 Maintenance Precautions 3.2 Disassembly/Assembly Procedures ....3.2.01 Preliminary Items ....3.2.02 Printhead Assembly ....3.2.03 Ribbon Protector ....3.2.04 Gear Case Assembly ....3.2.05 Pull-up Roller Assembly ....3.2.06 Upper Cover, Access Cover, and Sheet Guide Assemblies ....3.2.07 Control Board (FJIM) ....3.2.08 Power Supply Assembly ....3.2.09 Operator Panel PCB (LEOP) ....3.2.10 PC Connector
Page 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79
Table of Contents ....3.2.11 Space Motor and Roller Guide Assemblies ....3.2.12 Carriage Cable ....3.2.13 Space Rack ....3.2.14 Roller/Holder Backup Assembly ....3.2.15 Guide Rail and Adjust Cam ....3.2.16 Left Ground Plate ....3.2.17 Right Ground Plate ....3.2.18 Rear and Cut Sheet Paper Feed Sensor Levers ....3.2.19 Platen Assembly ....3.2.20 Paper Chute Assembly ....3.2.21 Line Feed Motor Assembly ....3.2.22 Reset Spring ....3.2.23 Idle Gear and Change Lever ....3.2.24 Pressure Spring ....3.2.25 Carriage Shaft ....3.2.26 Leaf Spring ....3.2.27 Bottom Paper Sensor Levers ....3.2.28 Front Pressure Roller Assembly ....3.2.29 Tractor Assembly ....3.2.30 Main Frame 3.3 Printer Adjustments ....3.3.02 Printhead Gap Adjustment ....3.3.03 Key Combinations ....3.3.04 Menu Operation ........Menu Settings ....3.3.05 Top of Form ....3.3.06 Paper Park ....3.3.07 Tear Feature ....3.3.08 Forms Tear Off ....3.3.09 Resets 3.4 Cleaning 3.5 Lubrication 3.6 Shipping Instructions 4 Failure & Repair Analysis ....4.1.01 Introduction ....4.1.02 Printer Serial Number Identification ....4.1.03 Firmware Revision Identification 4.2 Reporting Problems - General Information ....4.2.02 Problem Lists ....4.2.03 Reporting Methods 4.3 Troubleshooting Updates 4.4 Troubleshooting Tips ....4.4.02 Problem Categories ....4.4.03 START HERE Flowchart
Page 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122
Table of Contents ....4.4.04 Tips for Preventing Image Problems ....4.4.05 Common Problems 4.5 Abnormal Output - Output Samples ....Left Margin Drifting Problem 4.6 Fault Alarms ....4.6.02 ALARM/LED Display Troubleshooting Table Index ....4.6.03 ALARM/LED Display Troubleshooting Tables 4.7 Repair Analysis Procedures (Raps) ....4.7.02 RAP Index ........RAP 01 No Power Supplied to Printer ........RAP 02 No Spacing Operation ........RAP 03 Printhead Homing Error ........RAP 04 Paper Jam During Paper Loading ........RAP 05 Printhead Pins Not Firing ........RAP 06 Poor Print Quality ........RAP 07 Ribbon Feed Problem ........RAP 08 Line Feed Problem ........RAP 09 Operation Panel Malfunction ........RAP 10 Parallel Interface Problem ........RAP 11 Serial Interface Problem 4.8 Printer Tests ....4.8.02 Rolling ASCII Test ....4.8.03 Font Test ....4.8.04 Serial Interface Loopback Test ........Serial Cable Information ........Serial Interface Signal Requirements ........Commonly Used Serial Cable Configurations ....4.8.05 Hexadecimal Dump Mode 4.9 Resistance Checks ........Layout Diagram ....4.9.02 Printhead ....4.9.03 Line Feed Motor Resistance ....4.9.04 Space Motor Resistance A Reference Charts A.1 Overview - A.1.01 General Information A.2 Index To Charts ........Board Layout ....A.2.01 Main Controller Board (FJIM) ....A.2.02 Operator Panel Board (LEOP) ....A.2.03 Power Supply Assembly ....A.2.04 Space Motor Board ....A.2.05 RS232-C Serial Interface Board - Option (LXHI) B Illustrated Parts Listing B.1 Overview - B.1.01 General Information
Page 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164
Table of Contents ........Format ........Current Part Numbers ....B.1.02 Definition of Terms ....B.1.03 Parts Ordering Information B.2 Charts ........Overview ....B.2.01 Printer ....B.2.02 Upper Cover Assembly ....B.2.03 Printer General Assembly ....B.2.04 Printer Unit ....B.2.05 Printer Unit ....B.2.06 Printer Unit ....B.2.07 Carriage Assembly ....B.2.08 Options ....B.2.09 Option Parts ....B.2.10 Consumables ....B.2.11 Packing Materials ....B.2.12 Documentation ....B.2.13 Service Training Kit Revision List
Page 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183
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Service Guide ML520/521
Chapter 0 About This Manual
This document may not be reproduced without the written permission of the Okidata Technical Training Group. Every effort has been made to ensure the accuracy of the information contained in this training course. Okidata is not responsible for errors beyond its control. © 1994 by Okidata All rights reserved. First Edition Second Edition Third Edition February, 1993 September, 1993 December, 1994 P/N 59257801 P/N 59257802 P/N 59257803
Written and produced by the Okidata Technical Training Group Please address any comments on this publication to: Technical Training Group Okidata 532 Fellowship Road Mount Laurel, NJ 08054-3499 Fax Number: (609) 235-2600, ext. 7034 Okilink Login Name: Technical Training OKIDATA is a registered trademark of Oki Electric Industry Company, Ltd.; marques deposee de Oki Electric Industry Company, Ltd.; marca registrada, Oki Electric Industry Company, Ltd. MICROLINE is a registered trademark of Oki Electric Industry Company, Ltd.; marque depose de Oki Electric Industry Company, Ltd. OkiSmart Paper Handling is a trademark of Oki Electric Industry Company, Inc. PLUG n PRINT is a registered trademark of Oki America, Inc.; marque deposee de Oki America, Inc. Bitstream is a registered trademark of Bitstream Incorporated. Epson is a registered trademark of Seiko Epson Corporation. IBM is a registered trademark of International Business Machine Corporation. MS-DOS is a registered trademark of Microsoft Corporation. PC is a registered trademark of International Business Machine Corporation.
Proprinter is a registered trademark of International Business Machine Corporation. Windows is a trademark of Microsoft Corporation Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)
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Service Guide ML520/521
Chapter 1 Product Specifications
1.1.01 General Information The Microline 520 and Microline 521 are letter quality, nine-pin, dot-matrix printers which utilize OKISMART paper handling. Patented Okidata technology does away with the manual head gap adjustment. The printer actually reads and learns the print medium being used, then automatically adjusts the head gap to the optimum distance. This autogapping process leads to longer printhead life. Options include the Bottom Feed Push Tractor, Cut-Sheet Feeder, Pull Tractor and Serial Interface Board. The Microline 520 is an 80 column printer. The Microline 521 is a 132 column printer. Okidata's one year limited warranty covers the parts, labor and printhead on both printers. The following items are available for the printer.
OKISMART Typer - software which provides the flexibility for the Microline 590/521 to function like a typewriter on checks, labels and envelopes. OKISMART Panel - a utility program that lets you control selected printer functions from your personal computer.
Scalable Fonts - 14 scalable fonts, available on diskette.
NOTE: The OkiSmart software includes three programs. 1. OkiSmart Control 2. OkiSmart Panel Emulator 3. OkiSmart Setup Refer to the Printer Handbook for more information.
Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)
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Service Guide ML520/521
Chapter 1 Product Specifications
1.2 PHYSICAL SPECIFICATIONS 1.2.01 Dimensions
NOTE: Dimensions INCLUDE the platen knob, acoustic cover, and paper separator.
Microline 520 Width: 16.9 inches (43 centimeters) Depth: 14.9 inches (37.8 centimeters) Height: 6.5 inches (16.5 centimeters) Microline 521 Width: 23 inches (58.4 centimeters) Depth: 14.9 inches (37.8 centimeters) Height: 6.5 inches (16.5 centimeters) 1.2.02 Printer Weight Microline 520 17.6 pounds (8.0 kilograms) Microline 521 23.1 pounds (10.5 kilograms)
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Service Guide ML520/521
Chapter 1 Product Specifications
1.3 POWER REQUIREMENTS 1.3.01 Input Power 120 VAC: +5.5 / -15% 230/240 VAC: +10 / -14% 1.3.02 Power Consumption Operating: 110 VA Idle: 40 VA Local Test: 70 VA 1.3.03 Power Frequency 120 VAC: 60 Hz +/- 2% 230/240 VAC: 50/60 Hz +/- 2%
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Service Guide ML520/521
Chapter 1 Product Specifications
1.4 ENVIRONMENTAL CONDITIONS 1.4.01 Acoustic Rating Near Letter Quality Mode Microline 520 54.9 dBA Microline 521 54.4 dBA Utility Mode Microline 520 57.2 dBA Microline 521 56.9 dBA Quiet Mode Microline 520 52.5 dBA Microline 521 52.3 dBA
1.4.01 Altitude 10,000 feet (3,050 meters)
1.4.03 Ambient Temperature and Relative Humidity (RH) While operating: 41 to 104 degrees Fahrenheit (5 to 40 degrees Celsius) Operating humidity: 20% to 80% RH While in storage: 14 to 122 degrees Fahrenheit ( - 10 to 50 degrees Celsius) Storage humidity: 5% to 95% RH
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Service Guide ML520/521
Chapter 1 Product Specifications
1.5 AGENCY APPROVALS 1.5.01 Listings UL No: UL Standard No. 1950 D3 CSA No: CSA Standard 22.2-950 D3 FCC: FCC Certified per Part 15, Subject J, Class B IEC: IEC 950 VDE: VDE 0805 VDE 0875 Class B BS: BS 7002
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Service Guide ML520/521
Chapter 1 Product Specifications
1.6 OPERATIONAL SPECIFICATIONS 1.6.01 Character Matrix Sizes Table of Print Speed and Character Matrix Near Letter Quality Mode Speed 80 (12cpi) Matrix (H x V) 17 x 13
Utility 320 (12cpi) 9x7
High Speed Draft 427 (12cpi) 7x7
Print Speed at Different CPI for the ML 520/521 Mode HSD CPI 10 12 15 17.1 20 Utility 10 12 15 17.1 20 LQ 10 12 15 17.1 20 CPS 427 427 427 427 427 320 320 320 320 320 80 80 80 80 80 Horiz. DPI 90 108 135 154 180 120 144 180 206 240 240 288 360 412 480 Vert. DPI 72 72 72 72 72 72 72 72 72 72 144 144 144 144 144 IPS 42.7 35.6 28.5 25.0 21.4 32 26.7 21.3 18.6 16.0 16.0 13.3 13.3 9.32 8.0
1.6.02 Characters Per Line Microline 520
Characters Per Line 80 96 120 137 160 Microline 521 Characters Per Line 136 163 204 233 272
Characters Per Inch 10 12 15 17.1 20
Characters Per Inch 10 12 15 17.1 20
1.6.03 Character Pitches 5, 6, 8.5, 10, 12, 15, 17.1, 20 1.6.04 Character Sets Standard ASCII EPSON Character Set I & II IBM Character Set I, II & All Characters Foreign Character Substitution International Character Sets Code Page 850, 860, 863, 865 and 437 Line Graphics Bar Code Code 39 UPC A UPC E EAN 8 EAN 13 Interleaved 2 of 5 Code 128 (A, B, C) Postnet
1.6.05 Emulations
NOTE: The emulations are co-resident
Epson FX IBM Proprinter Microline Standard 1.6.06 Fonts Near Letter Quality Courier Utility Gothic High Speed Draft Gothic Bar Code Code 39 UPC A UPC E EAN 8 EAN 13 Interleaved 2 of 5 Code 128 (A, B, C) Postnet 1.6.07 Front Panel Switches SELECT / Menu Micro Feed Up / Down Shift Paper Park Line Feed Pitch Selection FORM FEED / Load Print Quality Selection Top of Form Tear Quiet Reset 1.6.08 Graphics Resolution Graphics Resolution: 288 (horizontal) x 144 (vertical) dots per inch (DPI) maximum 1.6.09 Interface Standard Centronics Parallel Optional
RS232C Serial 1.6.10 Line Feed Increments Fixed 6 lines per inch (lpi) [0.167 inch (4.23 millimeters)] 8 lines per inch (lpi) [0.125 inch (3.175 millimeters)] Variable n/60 inch n/72 inch n/144 inch n/216 inch 1.6.11 Line Feed Time 65 milliseconds 6 lines per inch (lpi) 6 milliseconds 8 lines per inch (lpi) 1 second 5.0 inches (Continuous paper feed rate) 1.6.12 Menu Mode Switch Paper park Line Feed / Reverse FORM FEED / Load Tear SEL / Menu Action Prints the entire menu. Selects Group Function Selects Item Selects Item Value Exits Menu Mode, Enters Select
1.6.13 Paper Feed Methods Standard Friction Feed (Top) Rear Push Tractor (Rear) Optional Pull Tractor (Bottom) Bottom Push Tractor Feed (Bottom) Single-Bin Cut Sheet Feeder (Top) CSF 5000 - Narrow CSF 5001 - Wide 1.6.14 Paper Feed Paths Top Feed (Standard) Rear Feed (Standard) Bottom Feed (by using an Optional feed mechanism) Special Features
Paper Park Automatic Paper Loading Forms Tear Off 1.6.15 Paper Loading Auto Loading (Top Feed) Press FORM FEED / Load switch to feed paper to default position 1.6.16 Paper Out Detection Distance from end of paper Rear Feed: 0.5 inches (12.7 mm) Bottom Feed: 0.5 inches (12.7 mm) Top Feed: 0.5 inches (12.7 mm) 1.6.17 Paper Tear Capabilities Forms Tear-0ff (sharp edge on access cover) Metal Tear Bar (with optional bottom feed tractor unit)
1.6.18 Print Method Printhead Type General Information Impact: Dot Matrix 9 pin printhead .0134 inch (0.34 millimeter) diameter pins Overheat Protection When printhead temperature exceeds 110 degrees Celsius, the printer stops bi-directional printing. Uni-directional printing begins. If the temperature exceeds 118 degrees Celsius, printing stops. Printing will resume when the printhead temperature drops below 118 degrees Celsius.
NOTE: Refer to Section Two for more information on printhead operation.
Printhead Gap Information Three items factor into printhead gap information:
1. Printhead Gap Adjustment This is a SERVICE ADJUSTMENT made by a technician. It is covered in Section 3.3 of this Service Handbook. The Adjustment measures 0.014 +/- 0.001 inches 90.35, +/-0.03 mm). 2. Printhead Gap Adjustment This is a MENU ITEM in the SET-UP Group. It fine tunes the automatic setting of the printhead gap. The settings are 0, 1 and -1. Use 1 to darken print (if output is consistently light). Use -1 to lighten print (if output is consistently dark). 3. Gap Control This is a MENU ITEM in each (Paper Feed) Group. The Groups are REAR FEED, BOTTOM FEED, and TOP FEED. Gap Controls determines how the printhead gap is set. The settings are listed below. Auto Gap, Semi Auto Gap, 1, 2, 3, 4, 5, 6, 7, 8, 9 An explanation of each setting follows. Auto Gap This is the factory default. Automatically determines paper thickness of the first page. During single-sheet feed, each page's thickness is checked while a job is printing. Semi Auto Gap Similar to Auto Gap. Automatically determines paper thickness of the first page. During single-sheet feed, each page's thickness IS NOT checked "while" a job is printing. 1, 2, 3, 4, 5, 6, 7, 8, 9
Used when the same paper is used ALL of the time. Bypasses the automatic head gap adjustment. 1 is the narrowest head setting. 9 is the widest head setting.
1.6.19 Print Modes Near Letter Quality Utility High Speed Draft 1.6.20 Print Speed Table of Print Speed and Character Matrix Mode Near Letter Quality Speed 80 (12 cpi) Matrix (H x V) 17 x 13
Utility 320 (12 cpi) 9x7
High Speed Draft 427 (12 cpi) 7x7
Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)
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Service Guide ML520/521
Chapter 1 Product Specifications
1.7 PAPER SPECIFICATIONS CAUTION: Use Bottom Feed and/or optional Pull Tractor for card stock and labels. 1.7.01 Types Card Stock Weight: 120 lbs. (450 g/m 2 ) Maximum Width: Microline 520 5 to 8 inches (12.7 to 20.3 centimeters) Microline 521 5 to 14 inches (12.7 to 35.6 centimeters) Length: 3 to 17 inches (7.62 to 43.18 centimeters) Thickness: .017 inches (0.44 millimeters) Paper Feed Path: Bottom Printhead Gap Information: Refer to the Printhead Gap Information, Section 1.6 Continuous Form Weight: Single Part 12 - 24 lb. (45 to 90 g/m 2 ) Multi-Part, Carbonless 9 - 11 lb. (35 to 40 g/m 2 ) Multi-Part, Interleaf Paper 10 - 12 lb. (38 to 45 g/m 2 ) Carbon 9 lb. (35 g/m 2 ) Width: Microline 520 3.5 to 10.5 inches (8.8 to 26.6 centimeters) Microline 521 3.5 to 16.5 inches (8.8 to 41.9 centimeters) Length: 3 to 17 inches (7.62 to 43.18 centimeters) Thickness: 0.014 inches (0.36 millimeters) Rear Feed 0.017 inches (0.44 millimeters) Bottom Feed Paper Feed Path: Rear or Bottom Printhead Gap Information: Refer to the Printhead Gap Information, Section 1.6 Cut Sheet Weight: 12 to 24 lbs. (45 to 90 g/m 2 )
Width: 7.2 to 14.3 inches (18.3 to 36.3 centimeters) Width: Microline 520 7.2 to 8.5 inches (18.2 to 21.5 centimeters) Microline 521 7.2 to 14.3 inches (18.2 to 36.3 centimeters) Length: 3 to 17 inches (7.62 to 43.18 centimeters) Thickness: 0.014 inches (0.325 millimeters) Maximum Paper Feed Path: Top Printhead Gap Information: Refer to the Printhead Gap Information, Section 1.6. Envelopes Weight: 24 lbs. (90 g/m 2 ) Maximum Size: Single Feed Minimum: 6.5 x 3.6 inches (16.5 x 9.1 centimeters) Maximum: 9.5 x 4.1 inches (24.1 x 10.4 centimeters) Continuous Non-overlap type Thickness: .014 inches (.325 millimeters) Maximum Paper Feed Path: Bottom Printhead Gap Information: Refer to the Printhead Gap Information, Section 1.6. Labels Weight: N/A Width: Microline 520 3.5 to 10.5 inches (8.8 to 26.6 centimeters) Microline 521 3.5 to 16.5 inches (8.8 to 41.9 centimeters) Length: 3 to 17 inches (7.62 to 43.18 centimeters) Thickness: .011 inches (0.28 mm) Maximum (including backing) Paper Feed Path: Bottom Printhead Gap Information: Refer to the Printhead Gap Information, Section 1.6. CAUTION: Use Bottom Feed and/or optional Pull Tractor for card stock and labels. Transparency
NOTE: Roller marks may mar the transparency under high temperature / high humidity conditions.
Weight: 12 to 24 lbs. (45 to 90 g/m 2 ) Width: Microline 520 7.2 to 8.5 inches (18.2 to 21.5 centimeters) Microline 521 7.2 to 14.3 inches (18.2 to 36.3 centimeters) Length: 3 to 17 inches (7.62 to 43.18 centimeters) Thickness: 0.14 inches (0.36 millimeters) Paper Feed Path: Top Printhead Gap Information: Refer to the Printhead Gap Information, Section 1.6. 1.7.02 Length
NOTE: The recommended length is specific to paper type.
Rear Feed Minimum 3 inches (7.62 centimeters) Maximum 17 inches (43.18 centimeters) Bottom Feed Minimum 3 inches (7.62 centimeters) Maximum 17 inches (43.18 centimeters) Top Feed Minimum 3 inches (7.62 centimeters) Maximum 17 inches (43.18 centimeters) 1.7.03 Number of Copies Original + 4 Interleaf Original + 4 Carbonless Original Cut Sheet 1.7.04 Thickness 0.014 inches / 0.36 mm Maximum Thickness, Rear Feed 0.017 inches / 0.44 mm Maximum Thickness, Bottom Feed 1.7.05 Weight
NOTE: The recommended weight is specific to paper type.
Minimum: 9 lb. (35 g/m 2 ) Maximum: 120 lb. (90 g/m 2 ) 1.7.06 Width
NOTE: The recommended width is specific to paper type.
Paper Microline 520 Minimum: 3.5 inches ( 8.8 centimeters) Maximum: 10.5 inches (26.6 centimeters) Microline 521 Minimum: 3.5 inches ( 8.8 centimeters) Maximum: 16.5 inches (41.9 centimeters) Printing Area Microline 520 8 inches Maximum Microline 521 13.6 inches Maximum
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Service Guide ML520/521
Chapter 1 Product Specifications
1.8 MEMORY SPECIFICATIONS 1.8.01 EEPROM 1 Kbit serial EEPROM (used to store Menu data) 1.8.02 EPROM 1 MBit EPROM (Printer Control Program - Fonts) 1.8.03 RAM 128 Kbyte Total Resident RAM Used as Receive Buffer Receive Buffer Size is selected through the Menu. Settings are: 64 K, 32 K, 1 line Print Buffer DLL Buffer Scratch Pad
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Service Guide ML520/521
Chapter 1 Product Specifications
1.9 CONSUMABLES 1.9.01 Ribbon CAUTION: Using a non-Okidata ribbon may damage the printhead and void any warranties. Material Nylon fabric, cartridge type, re-inking Type Black Ribbon Life (On average, at 10 characters per inch, Utility Mode) 4 million characters Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)
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Service Guide ML520/521
Chapter 1 Product Specifications
1.10 OPTIONS - Cut Sheet Feeders 1.10.01 Cut Sheet Feeders Single Bin The CSF-5000 is a narrow feeder for the Microline 520. Single Bin with envelope capability Paper Width: 7.2" to 8.5" (18.3 cm to 36.3 cm) Paper Length: 10.1" to 14" (25.6 cm to 35.6 cm) Capacity: 170 sheets (16 lb.), 100 sheets (20 lb.) The CSF-5001 is a wide feeder for the Microline 521. Single Bin with envelope capability Paper Width: 7.2" to 14.3" (18.3 cm to 36.3 cm) Paper Length: 10.1" to 14" (25.6 cm to 35.6 cm) Capacity: 170 sheets (16 lb.), 100 sheets (20 lb.)
Dual Bin P/N 70022601 is a narrow feeder for the Microline 520. Dual Bin with envelope capability Paper Width: 7.2" to 8.5" (18.3 cm to 36.3 cm) Paper Length: 10.1" to 14" (25.6 cm to 35.6 cm) Capacity: 170 sheets (16 lb.), 100 sheets (20 lb.) P/N 70022801 is a wide feeder for the Microline 521. Dual Bin with envelope capability Paper Width: 7.2" to 14.3" (18.3 cm to 36.3 cm) Paper Length: 10.1" to 14" (25.6 cm to 35.6 cm) Capacity: 170 sheets (16 lb.), 100 sheets (20 lb.)
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Service Guide ML520/521
Chapter 1 Product Specifications
1.10.02 Pull Tractor Kit
NOTE: The Pull Tractor Kit (P/N 70023001) is a narrow feeder for the Microline 520. The Pull Tractor Kit (P/N 70023201) is a wide feeder for the Microline 521.
Bottom Feed Rear Feed (For Push/Pull Operation) Paper Types: Continuous Feed and Labels
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Service Guide ML520/521
Chapter 1 Product Specifications
1.10.04 Bottom Push Tractor Kit
NOTE: The Bottom Push Tractor Kit (P/N 70022901) is a narrow feeder for the Microline 520. The Bottom Push Tractor Kit (P/N 70023101) is a wide feeder for the Microline 521.
Bottom Feed Paper Type: Continuous Feed Includes: Stand and Metal Tear Bar
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Service Guide ML520/521
Chapter 1 Product Specifications
1.10.05 Serial Interface Super-Speed 19.2K RS-232C Ready/Busy/X-On/X-Off Protocols Can be configured through the Menu or OKISmart Utility Program
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Service Guide ML520/521
Chapter 1 Product Specifications
1.10.06 Roll Paper Stand Adapts printer for use with roll-type paper (Model 520 only) Includes: Stand, Support, Cord and DIN plug for connection to printer
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Service Guide ML520/521
Chapter 1 Product Specifications
1.10.08 OKISmart Typer Utility Obtained via BRC (Business Reply Card) packaged with printer Includes: Typewriter Mode, Form Creation Utility and Barcode Utility 1.10.09 OKISmart Panel Utility Obtained via BRC (Business Reply Card) packaged with printer Includes: Front Panel Control Utility and Drivers for Windows 3.0 & 3.1
NOTE: The OKISmart software includes three programs. 1. OKISmart Control 2. OKISmart Panel Emulator 3. OKISmart Setup Refer to the Printer Handbook for more information.
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Service Guide ML520/521
Chapter 1 Product Specifications
1.11 RELIABILITY 1.11.01 Mean Time Before Failure (MTBF) Approximately 6,000 hours: 25% duty cycle / 35% page density 1.11.02 Mean Time To Repair (MTTR) Approximately 15 minutes to major sub-assembly level 1.11.03 Printer Life Approximately 16,000 hours of power-on time: 25% duty cycle / 35% page density 1.11.04 Printhead Life Average 200 million characters in 10 cpi utility mode @ normal 25% duty, 35% page density 1.11.05 Ribbon Life Approximately 4 million characters 1.11.06 Warranty (Limited) One year, parts and labor 1.11.07 Service Authorized OKIDATA Service Centers
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Service Guide ML520/521
Chapter 2 Principles of Operation
2.1 ELECTRICAL OPERATION The printer is comprised of the electrical components listed below. Main Control Board Power Supply Assembly Transformer Filter Board Operator Panel Space Motor / Line Feed Motor Printhead Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)
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2.1.01 Main Control Board The main control board is made up of the microprocessor, peripheral circuits, drive circuits, sensors and interface connectors. The power to the main control board is supplied by the transformer assembly through a wire harness. The power to other electrical parts (line feed motor, space motor and printhead) is provided by the power supply circuitry through connectors on the main control board. Microprocessor (MPU) (Location 04C: 67X640) 16 bit MPU, using CMOS technology. The MPU contains a 20 bit address bus, a 16 bit data bus. The MPU can access 1 Mbyte of program memory and 1 Mbyte of data memory space. The microprocessor controls the entire printer by executing the control program through LSIs and the driver circuits. the
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Block Diagram
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Program ROM Location 05CA: 27C1024 This 64k x 16 bit (1Mbit) EPROM contains the control program for the printer. The MPU executes the instructions contained in this program. The Program ROM is assigned to the program memory area of the MPU and instructions are fetched by the PSEN signal of the MPU.
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Chapter 2 Principles of Operation
RAM Location 05CB: 511664Z The RAM is CMOS dynamic RAM with 65,536 words x 16-bit configuration. It is used as a receive buffer, print buffer and work buffer.
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LSI Location 04B: MSM79VO35 Detects the output of the two-phase sensor on the DC space motor to control the motor drive phase. Transmits and receives serial data to and from the printhead based on the dot timing (which is derived from the space motor speed). Controls the external interface. The LSI is connected to the MPU.
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Electrically Erasable Programmable Read Only Memory (EEPROM) (Location 03C: 93CS46) The EEPROM is a CMOS serial I/O type memory (EEPROM). It is capable of electrically erasing and writing 1,024 bits. The EEPROM contains the menu data and the head drive time correction data.
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Chapter 2 Principles of Operation
2.1.02 Initialization This printer is initialized when the printer is powered on or when the I-PRIME-N signal is input from the host via the parallel interface. The steps in Printer Initialization are listed below. The RST-N signal is output from the reset circuit to reset the MPU and LSIs. The program is executed and the LSIs are reset by the MPU via IORST-N.
NOTE: A reset operation initiated by I-PRIME does not reset the MPU.
The program sets the LSI (02D) mode, checks the memory (ROM/RAM), then executes carriage homing and determines the phase of the line feed motor. Finally, the program establishes the interface signals (P-I/F: ACK-P signal sending, and S-I/F: BUSY-N signal off) and lights the SELECT lamp to indicate that the printer is in the ON-LINE state.
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2.1.03 Parallel Interface Control The parallel data input from the host to the interface LSI is latched to the internal register at the falling edge of the STROBE-N signal. The LSI sets the BUSY-N signal to inform the host that the data is being processed. The LSI also outputs the RXD-N signal to inform the MPU of data reception. The data is read upon receiving the RD-N signal from the MPU. When the data processing is complete, the BUSY-N signal is disabled and the ACK-N signal is sent to request the next data. When the buffer is full and reception is not desired, the BUSY signal is sent to request data transmission be stopped.
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2.1.04 Print Control The print data is transmitted as serial data from the LSI to the control circuit and the driver contained in the printhead. After the data is printed, the sensor analog circuit controlling each pin returns the pin stroke data to the MPU. The MPU will make an automatic head gap adjustment. This feedback system sets the optimum drive time for each pin in order to maintain high print quality. In the case of envelopes, where the medium thickness varies as the printhead moves along the platen, the strike force of the pins changes to compensate for the differences in thickness.
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LSI/Printhead Interface The connection between the LSI and the printhead is made with the bi-directional serial data bus. The LSI transmits the print data as serial data to the logic circuit of the printhead. The printhead returns serial data from the printhead sensor analog circuit to the LSI. This information is used to determine the optimum drive time for the next print request. The logic circuit of the printhead signals the LSI if a parity error is detected in the print data.
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Gap Adjust Control The Gap Adjust LSI receives stroke length information for all of the printhead pins from the sensor analog circuit. The Gap Adjust LSI then sets the optimum printhead gap for the printing medium.
NOTE: Refer to Section 2.2.03 for a description of the mechanical process. All values in the below chart are in millimeters
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Print Compensation Control The printhead compensates for the shape of the platen as shown below.
NOTE: Also refer to Section 2.1.07 - Head Drive Time
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2.1.05 Space and Line Feed (SP/LF) Motor Control The LSI (Location 04B: MSM79V035) generates the space motor and the line feed motor control signals according to commands received from the MPU. These signals are sent to the SP/LF motor driver.
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Line Feed Motor Control The SP/LF motor driver (Location 5A: MHM2025) drives the line feed motor in two-phase bipolar, based on the phase changeover data output from the LSI. The serial data from the LSI (04B: MSM79V035) is processed by a register contained in the SP/LF motor driver to measure the overdrive time and to change the phase.
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Space Motor Control The SP/LF motor driver (Location 5A: MHM2025) drives the three-phase brushless motor. Motor movement is based on the phase signal (SPU, SPV and SPW) and the speed instruction data from the LSI. The MPU can identify the current speed of the space motor by measuring the pulse width of the output (Phase A, Phase B) of the encoder disk sensor. After comparing the target speed for each print mode with the actual speed, the motor is accelerated or decelerated to maintain the desired speed for each print mode.
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Encoder Disk As the space motor operates, the encoder disk spins. When the encoder disk interrupts the photo sensors, the signals Phase A and Phase B are generated. The LSI (Location 04B: MSM79V035) divides these edge pulse signals (the frequency division is based on the selected print pitch) to generate the signal IPT. The IPT signal provides dot-on timing and carriage position detection timing.
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2.1.06 Operation Panel The Serial I/O Port (Ports 20 - 23) of the MPU reads the operation panel switch data from the operation panel control LSI (Location IC1: BUS148S). A two byte (15 bits +1 parity bit (even parity)) command (OPTXD) is transmitted from the MPU to the operation panel LSI in synchronization with the OPCLK signal. Once the LSI decodes the command, the command must pass a command code check and have no parity errors. Then, the specified I/O control will return the two byte command response to the MPU.
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2.1.07 Alarm Circuit Driver Circuit Alarm Processing The printhead driver output and the head gap magnet output drive signals are monitored at R29 and C8. The POWER OFF-P signal is output by the comparator (Location 02C: IC2901) when driven for more than the specified time. This signal becomes the ALM signal. The ALM signal is sent to the power supply board and causes the DC voltages to be turned off.
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Low Motor Drive Voltage Alarm +40V is converted into the POWLEV signal (0 vdc to +5 vdc) by the voltage divider network of R542 and R544, then input to the A/D port of the MPU. The value of this voltage is used to control the drive time and the print speed (pass number) of the head.
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Head Drive Time The head drive time is modified to compensate for the amount of the voltage drop of the POWLEV signal. By monitoring the voltage drop every 500 microseconds, the MPU is able to control and maintain the impact necessary for each printhead pin.
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Print Speed
Actual Voltage (+40 vdc) +34 vdc or greater +32 vdc to +34 vdc +30 vdc to +32 vdc +30 vdc or less
Passes Required 1 1 1 2
Relative Print Speed 100% Approximately 85% Approximately 50% Less than 50%
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Head Overheat Alarm Processing If the printhead temperature exceeds 110 degrees Celsius, the printer will switch to uni-directional print. If the temperature exceeds 118 degrees Celsius, printing will stop. Once the printhead cools, printing will resume. Two thermistors are used to monitor the printhead temperature. One is contained in the printhead. The other is in the printhead driver. A thermistor in the printhead prevents over-heating of the coil during periods of continuous bi-directional printing. If the temperature of the coil exceeds the pre-determined limits, the control circuit detects the thermistor signal (TSD). Another thermistor monitors the temperature of the printhead driver. If the temperature of the driver exceeds the pre-determined limits, the control circuit detects the thermistor signal (TSD). The voltage of the TSD signal is monitored at the MPU A/D port to control the pass number and print method (uni-directional / bi-directional) at each of seven levels.
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2.1.08 Power Supply Circuit The switching type power supply circuit supplies the +5 vdc, +/-8 vdc, 10 VAC and +40 vdc.
Voltage/Signal +5 vdc +8 vdc +10 VAC +40 vdc
Purpose IC logic levels, LED drive voltages Serial interface line voltage, comparator IC Serial interface line voltage and the printhead analog circuit Printhead, space motor and line feed motor drive voltage
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2.2 MECHANICAL OPERATION 2.2.01 Printhead Mechanism The printhead is a spring-charged, 9-pin printhead. It is attached to the carriage, which moves parallel to the platen. Electrically, the printhead is controlled by the main control board via the carriage cable and the space motor. The printhead is composed of the following parts. Wire Guide Spring Assembly Wire, Armature, Spring, Yoke, Spacer Magnet Assembly Magnet, Core, Coil, Yoke Printed Circuit Board Logic Control, Print Driver, Analog Sensor Control and Thermistor Cooling Fin
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Printhead Gap Information Three items factor into printhead gap information. 1. Printhead Gap Adjustment This is a SERVICE ADJUSTMENT made by a technician. It is covered in Section 3.3 of this Service Handbook. The Adjustment measures 0.014, +/- 0.001 inches (0.35, +/- 0.03 mm). 2. Printhead Gap Adjust This is a MENU ITEM in the SET-UP Group. It fine tunes the automatic setting of the printhead gap. The settings are 0, 1, and -1. 0 is the factory default. Use 1 to darken print (if output is consistently light). Use - 1 to lighten print (if output is consistently dark). 3. Gap Control This is a MENU ITEM in each [Paper Feed] Group. The Groups are REAR FEED, BOTTOM FEED, and TOP FEED. Gap Control determines how the printhead gap is set. The settings are listed below. Auto Gap, Semi Auto Gap, 1, 2, 3, 4, 5, 6, 7, 8, 9 An explanation of each setting follows.
Auto Gap This is the factory default. Automatically determines paper thickness of the first page. During single-sheet feed, each pages thickness is checked while a job is printing.
Semi Auto Gap Similar to Auto Gap. Automatically determines paper thickness of the first page. During single-sheet feed, each pages thickness IS NOT checked while a job is printing. 1, 2, 3, 4, 5, 6, 7, 8, 9 Used when the same paper is used ALL of the time. Bypasses the automatic head gap adjustment. 1 is the narrowest gap setting. 9 is the widest gap setting.
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Interconnect Diagram: Control Board to Printhead
NOTE: The printhead coil resistance values ARE NOT LISTED. The individual printwire control lines CANNOT be accessed on this printhead.
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Line Feed Motor Resistance The resistance of each coil should be approximately 13 ohms.
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Space Motor Resistance The resistance of each coil should be approximately 5 ohms.
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Printhead Operation When the printhead is idle, the armature is attracted to the permanent magnet. The print wires, which are attached to each armature, are then concealed inside the wire guide. When a signal to print a character is received, current flows through a coil. The magnetic field generated by the coil opposes the magnetic field between the armature and the permanent magnet. The armature is then driven in the direction of the platen by the force of the armature spring. The print wire (which is attached to the armature) protrudes from the tip of the wire guide and strikes the paper through the ribbon. This prints a dot on the paper. As the armature gets closer to the electrode of the analog sensor, the capacitance between them increases and a small amount of current flows. This current is amplified and sent to the logic control LSI to indicate armature activity. In order to attain optimum drive time, this information is transferred to the MPU. The MPU continually modifies the head gap to maintain the optimum drive time condition. The analog sensor element monitors all of the pins. The difference in pin stroke due to the curvature of the platen is compensated for at the logic control section of the printhead and is not transferred to the MPU. After the character has been printed, the permanent magnet attracts the armature and the print wires are retracted into the wire guide.
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Chapter 2 Principles of Operation
Printhead Temperature If the printhead temperature exceeds 110 degrees Celsius, the printer will switch to uni-directional print. If the temperature exceeds 118 degrees Celsius, printing will stop. Once the printhead cools, printing will resume. Two thermistors are used to monitor the printhead temperature. One is contained in the printhead. The other is in the printhead driver. A thermistor in the printhead prevents over-heating of the coil during periods of continuous bi-directional printing. If the temperature of the coil exceeds the pre-determined limits, the control circuit detects the thermistor signal (TSD). Another thermistor monitors the temperature of the printhead driver. If the temperature of the driver exceeds the pre-determined limits, the control circuit detects the thermistor signal (TSD). The voltage of the TSD signal is monitored at the MPU A/D port to control the pass number and print method (uni-directional / bi-directional) at each of seven levels. Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)
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2.2.02 Spacing Mechanism The spacing mechanism consists of a carriage shaft (mounted parallel to the platen), and a carriage frame which moves along the shaft. The carriage frame is driven by a DC servo motor mounted on the carriage frame. Items included in the spacing mechanism are listed below. Space Motor Assembly DC Servo Motor Motor Gear Sensor Encoder Disk Carriage Frame Carriage Shaft Space Rack Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)
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Spacing Operation The carriage frame, which contains the printhead and space motor, moves along the carriage shaft parallel to the platen. When the space motor rotates, the driving force is transmitted to the motor gear. As the motor gear rotates, the carriage moves along the platen. For every revolution of the DC servo motor, the carriage frame moves 0.8 inch (20.32 mm). As the DC servo motor rotates, a slotted disk (called the encoder disk), rotates with the servo motor and passes through the photosensor. The position of the carriage frame can be determined by counting the pulses generated by the photosensors. In the same way, the rotation of the space motor can be recognized and controlled by measuring the phase relationship and the pulsewidth of the signals generated by the photosensors.
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2.2.03 Head Gap Mechanism The head gap is automatically set for the thickness of the medium loaded in the printer. In the case of envelopes, where the medium thickness varies as the printhead moves along the platen, the strike force of the pins changes to compensate for the differences in thickness. Head Gap Setting Operation Once printing starts, the space motor rotates the ribbon gear, causing idle gear C to turn the change gear. When the MPU requests a change in the head gap setting, the GAP-P signal causes the armature (which is holding the change gear) to be attracted to the pranger magnet. The gap reset spring can now push the change gear so it contacts the gap change gear. The rotation of the gap change gear causes idle gear D to turn the adjust gear. The adjust gear turns the adjusting screw, resulting in a new head gap setting.
NOTE: As the adjusting screw turns counter-clockwise, the gap narrows. As the adjusting screw turns clockwise, the gap widens.
There is a cam at each setting of the gap change gear. When the change gear is at the top of the cam, the change gear disengages from the gap change gear. At this time, the armature resets, changing the head gap by one setting. The head gap is modified in .06 mm units for each range setting.
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Ribbon Drive Operation The ribbon drive mechanism feeds the ribbon in synchronization with the spacing operation. The force required to drive the ribbon is obtained from the space motor. The ribbon drive mechanism is composed of the items listed below. Ribbon Drive Gear Assembly Ribbon Gear This gear is located on the space motor assembly Ribbon Cartridge A continuous loop ribbon with uni-directional feed is used. Ink is supplied from an ink which is built into the ribbon cartridge. tank,
When the space motor turns, the ribbon gear on the spacing motor shaft rotates. The rotation is transmitted via a combination of gears, from the ribbon drive gear assembly to the drive gear in the ribbon cartridge. Although the space motor moves in both the forward and reverse directions during bi-directional printing, the gears in the ribbon drive assembly maintain uni-directional ribbon feed by switching the rotation direction of the gears.
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2.2.05 Line Feed Mechanism The line feed operation is accomplished by activating the line feed motor which turns the platen. The rotation of the platen is used to feed paper from the selected paper path. The components of the paper feed mechanism are listed below. Line Feed Motor (pulse motor), with gears Line Feed Idler Gear Platen Rear Tractor Feed Unit Pressure Roller
Change Lever (Paper Path Selection Lever) The change lever is used to select one of three different paper paths; top, rear or bottom. Paper Clamp Mechanism Moving the change lever between the bottom, top and rear positions, changes the positions of the front release gear arm and the release cam. The movement of the front release gear arm changes the position of the front release gear shaft. This causes the front pressure roller to open or close. The movement of the release cam causes the rear pressure roller to open or close.
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Cut Sheet/Continuous Sheet Switching Mechanism Top Feed (for cut sheet paper) When cut sheet paper is used during normal operation or by the Cut Sheet Feeder (CSF) option, place the change lever in the Top Feed position. As the platen turns, the platen gear causes the idle gear to rotate. At this time, the rear and front pressure rollers are pressed securely to the platen to feed the cut sheet. The cut sheet detection lever enables the cut sheet detection switch (which is located on the main control board). This places the printer in the cut sheet mode. When cut sheet paper is placed between the platen and the paper chute, the printer automatically feeds the sheet to the print start position. Rear/Bottom Feed (for continuous feed paper) When the continuous feed paper is used, either with the rear tractor, optional bottom tractor or optional pull tractor, place the change lever in the Rear/Bottom Feed position. When the change lever is placed in this position, the reset spring pushes the change gear. In this position, the idle gear is engaged with the bottom tractor unit drive gear and the tractor gear. As the platen turns, power is transferred from the platen gear, to the idle gear, to the change gear, and then to the push tractor shaft. CAUTION: The cut sheet / continuous sensor lever must be positioned below the BASW sensor. The lever should contact the sensor only when the change lever is in the top feed (middle) setting. If the lever is not correctly positioned, the ALARM lamp will light and the unit will not automatically load paper or receive data.
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Cut Sheet Paper Feed Operation As the line feed motor rotates, power is transferred through the decelerating gears (line feed idler gear, platen gear) to the platen. When using cut sheet paper, the change lever must be in the TOP position so the platen and pressure rollers can feed the paper. This also disengages the push tractor.
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Continuous Paper Feed (Rear Tractor Mechanism) As the platen rotates, power is transferred to the tractor gear from the platen gear, the idler gear, and the change gear. The tractor gear drives the pin tractor belts, which feed the continuous paper.
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Continuous Paper Feed (Pull Tractor Mechanism) Bottom feed of continuous sheets is possible only when an optional pull tractor unit is installed. As the platen rotates, power is transferred to the drive gear from the line feed idler gear, the platen gear, idler gear B and idler gear A. The drive gear turns the pull tractor assembly, which feeds the continuous paper.
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Continuous Paper Feed (Bottom Tractor Feed Mechanism) As the platen rotates, power is transferred to the drive gear from the platen gear, the idle gear and the tractor change gear. The drive gear turns the pin tractor belts on the bottom tractor feed unit, which feeds the continuous paper.
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Continuous Paper Feed (Push/Pull Tractor Mechanism) This mechanism consists of an optional pull tractor and a standard push tractor mechanism. Continuous paper is fed by these two tractors at the same time.
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Service Guide ML520/521
Chapter 2 Principles of Operation
2.2.06 Paper Detection Mechanism Top Feed Paper Detection When cut sheet paper is inserted into the printer, Point A of the Rear/Top Paper Feed Lever is pushed backward, causing the Sensor Lever to rotate. As the Sensor Lever rotates, it contacts the Rear Sensor Lever. This makes the Rear Sensor Lever rotate. The Rear Sensor Lever rotates, unblocking the Rear / Top Paper End Sensor (SNS1). Rear Feed Detection When paper is fed from the Rear Push Tractor, Point B is pushed backward. This makes the Sensor Lever rotate. As the Sensor Lever rotates, it contacts the Rear Sensor Lever. This makes the Rear Sensor Lever rotate. The Rear Sensor Lever rotates, unblocking the Rear / Top Paper End Sensor (SNS1). Bottom Feed Detection When the paper is fed from the bottom of the printer, Point C is pushed, rotating the Bottom Paper End Lever. As the Bottom Paper End Lever rotates, it contacts the Bottom Sensor Lever. This makes the Bottom Sensor Lever rotate. The Bottom Sensor Lever rotates, unblocking the Bottom Paper End Sensor (SNS2).
NOTE: The method for detecting a paper-end condition is the reverse of the above. PAPER-END is detected when the Bottom Paper End Sensor (SNS2) is blocked.
Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)
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Service Guide ML520/521
Chapter 2 Principles of Operation
2.2.07 Support Protector Mechanism During printer initialization, the support protector is latched in the stored position (approximately 5 mm from the left bracket of the main frame). Just before paper is loaded, the printhead moves towards the left bracket and unlatches the support protector. As the printhead moves to the right, the support protector reset spring pushes the support protector toward the center of the platen. With the support protector in this position, the ribbon protector and the support protector prevent the leading edge of the paper from curling or folding. Once the paper is ejected, the printhead slowly moves towards the left bracket. The support protector is latched in the stored position when it is pushed to approximately 5 mm from the left bracket.
Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)
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Service Guide ML520/521
Chapter 2 Principles of Operation
2.2.08 Automatic Paper Load The Microline 520/521 printers will automatically detect cut sheet paper and feed the paper to the Top of Form (TOF) position. Cut Sheet Paper Set the change lever to the TOP FEED position.
NOTE: When the change lever is in the TOP FEED position, the cut sheet detection lever contacts the cut sheet detection switch (BASW), which is located on the main control board.
Insert the sheet of paper between the platen and the paper chute. Once paper is detected at the paper end sensor and the amount of time selected on the Wait Time setting of the menu has lapsed, the line feed motor will feed the paper until the leading edge of the paper reaches the top of form position.
Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)
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Service Guide ML520/521
Chapter 2 Principles of Operation
Continuous Feed Paper Set the change lever to either the REAR FEED or BOTTOM FEED position.
NOTE: When the change lever is in the REAR FEED or BOTTOM FEED position, the cut sheet detection lever does NOT contact the cut sheet detection switch (BASW), which is located on the main control board.
Place continuous feed paper in the appropriate tractor. Press the FF/LOAD switch. The line feed motor will feed the paper until the leading edge of the paper reaches the top of form position.
Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)
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Service Guide ML520/521
Chapter 2 Principles of Operation
2.2.09 Paper Park If continuous feed paper is installed and printing on cut sheet paper is desired, it is not necessary to unload the continuous feed paper. The Paper Park feature provides a means of retracting the continuous feed paper from the paper path,