OKIDATA ML380 User manual

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Page: 1
Service Guide ML380
Chapter 0 About This Manual
ML380
Dot Matrix Printer
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 ML380
0 About This Manual
Front Cover 1
Manual Copyright 2
1 Product Specifications
1.1 Overview 3
1.2 Physical Specifications 4
1.3 Power Requirements 5
1.4 Environmental Conditions 6
1.5 Agency Approvals 7
1.6 Operational Specifications 8
1.7 Paper Specifications 9
1.8 Memory Specifications 10
1.9 Consumables 11
1.10 Options 12
1.11 Reliability 13
2 Principles of Operation
2.1 Principles of Operation - General Information 14
....2.1.02 Microprocessor and Peripheral Circuits 15
....2.1.03 Initialization 16
....2.1.04 Interface Control 17
....2.1.05 Printhead Drive Circuit 18
....2.1.06 Spacing Drive Circuit 19
....2.1.07 Line Feed Circuit 20
....2.1.08 Alarm Circuits 21
....2.1.09 Paper End Detection Circuit 22
....2.1.10 Power Supply 23
2.2 Mechanical Operation - Printhead Mechanism 24
....2.2.02 Spacing 25
....2.2.03 Ribbon Drive 26
....2.2.04 Paper Feed 27
....2.2.05 Paper-End Detection 28
....2.2.06 Semi-Automatic Sheet Feeder (SASF) 29
....2.2.07 Paper Park 30
3 Maintenance & Disassembly
3.1 Maintenance - General Information 31
....3.1.02 Maintenance Tools 32
....3.1.03 Maintenance Precautions 33
3.2 Disassembly/Assembly Procedures - General Information 34
....3.2.01 Paper Separator 35
....3.2.02 Printhead 36
....3.2.03 Upper Cover Assembly 37
....3.2.04 Space Rack 38

Table of Contents Page
....3.2.05 Ribbon Feed Gear Assembly 39
....3.2.06 Mini-Pitch (Space) Belt 40
....3.2.07 Head Connector Assembly 41
....3.2.08 Main Control Board (UMMB) 42
....3.2.09 Operation Panel 43
....3.2.10 Line Feed Motor 44
....3.2.11 Photosensor Assembly (Paper End) 45
....3.2.12 Bail Arms 46
....3.2.13 Carriage Frame 47
....3.2.14 Platen Assembly 48
....3.2.15 Pressure Roller Assembly 49
....3.2.16 Paper Pressure Guide 50
....3.2.17 Tractor Assembly 51
....3.2.18 Microswitch Assembly (SASF) 52
....3.2.19 Microswitch Assembly (Home Position Switch) 53
....3.2.20 Printer Mechanism 54
....3.2.21 Power Supply Unit 55
....3.2.22 Space Motor Assembly 56
....3.2.23 Bottom Paper Guide Lever 57
3.3 Printer Adjustments 58
....3.3.02 Gap Between Platen and Printhead 59
....3.3.03 Space Belt Tension 60
....3.3.04 Key Combinations 61
....3.3.05 Menu Operation / Menu Select Mode - General
Information 62
........From Print Mode 63
........From Power-OFF 64
........Printing the Menu 65
........Sample Menu 66
........Reset Menu to Factory Defaults 67
........Limited Operation 68
........Menu Settings 69
....3.3.06 Top of Form 70
....3.3.07 Paper Park 71
....3.3.08 Paper Tear Off 72
....3.3.09 Resets 73
3.4 Cleaning 74
3.5 Lubrication 75
3.6 Shipping Instructions 76
4 Failure & Repair Analysis
4.1 Failure & Repair Analysis - Introduction 77
....4.1.02 Printer Serial Number Identification 78
....4.1.03 Firmware Revision Identification 79
4.2 Reporting Problems - General Information 80

Table of Contents Page
....4.2.02 Problem Lists 81
....4.2.03 Reporting Methods 82
4.3 Troubleshooting Updates General Information 83
4.4 Troubleshooting Tips 84
....4.4.02 Problem Categories 85
....4.4.03 START HERE Flowchart 86
....4.4.04 Tips for Preventing Image Problems 87
....4.4.05 Common Problems 88
4.5 Abnormal Output 89
4.6 Fault Alarms - General Information 90
....4.6.02 Fault Alarm Lamp Display 91
4.7 Repair Analysis Procedures (RAPS) - Using The RAPS 92
....4.7.02 RAP Index 93
........RAP 01: No Power 94
........RAP 02: Space Operation Does Not Operate Normally 95
........RAP 03: Wrong Character or Missing Dots 96
........RAP 04: Line Feed Trouble 97
........RAP 05: Data Receiving Failure 98
4.8 Printer Tests - General Information 99
....4.8.02 Rolling ASCII Test 100
....4.8.03 Font Test 101
....4.8.04 Serial Interface Loopback Test - General Information 102
........Loopback Connector Configuration Diagram 103
........Procedure 104
........Serial Cable Information 105
........Serial Interface Signal Requirements 106
........Commonly Used Serial Cable Configurations 107
....4.8.05 Hexadecimal Dump Mode 108
4.9 Resistance Checks - General Information 109
....4.9.02 Main Control Board (UMMB) Voltage Check Points 110
....4.9.03 Connectors Block Diagram 111
....4.9.04 Connector Location 112
....4.9.05 Resistance Diagrams - Printhead 113
........Space and Line Feed Motors 114
....4.9.06 Head Cable Connection 115
A Board Diagrams
A1 Board Diagrams - General Information 116
A.2 Index To Charts 117
....A.2.01 Main Control Board (UMMB) Original 118
....A.2.02 Main Control Board (UMMB) Current 119
....A.2.03 RS232-C Serial Module (UMRS) 120
B Illustrated Parts Listing
B.1 Overview - General Information 121
....B.1.02 Definition of Terms 122

Table of Contents Page
....B.1.03 Parts Ordering Information 123
B.2 Charts 124
....B.2.01 Printer 125
....B.2.02 Covers 126
....B.2.03 Printer Unit 127
....B.2.04 Printer Mechanism (1 of 3) 128
....B.2.05 Printer Mechanism (2 of 3) 129
....B.2.06 Printer Mechanism (3 of 3) 130
....B.2.07 Option Parts 131
....B.2.08 Consumables 132
....B.2.09 Packaging 133
....B2.10 Documentation 134
....B.2.11 Service Training Kit Revision List 135

Page: 2
Service Guide ML380
Chapter 0 About This Manual
Manual Copyright
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 August, 1989 P/N 59238701
Second Edition September, 1993 P/N 59238702
Third Edition November, 1994 P/N 59238703
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: [phone], 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.
Centronics is a registered trademark of Centronics Inc.
PLUG n PRINT is a registered trademark of Oki America, Inc.; marque deposee de Oki America, Inc.
Epson is a registered trademark of Seiko Epson Corporation.
IBM is a registered trademark of International Business Machine 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)

Page: 3
Service Guide ML380
Chapter 1 Product Specifications
1.1 OVERVIEW
1.1.01 General Information
The Microline 380 is an 80 column, impact dot matrix printer using a 24 pin printhead. It emulates the
Epson LQ printer.
A push tractor is standard. An optional pull tractor is available.
Font and Character Pitch selection is available through the operator panel, printer menu, or through
software (using control codes).
A Centronics Parallel interface is standard. An RS232-C serial module is available as an option.
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)

Page: 4
Service Guide ML380
Chapter 1 Product Specifications
1.2 PHYSICAL SPECIFICATIONS
1.2.01 Dimensions
Width: 15.67 inches (398 millimeters)
Depth: 4.72 inches (120 millimeters)
Height: 13.58 inches (345 millimeters)
NOTE: Dimensions DO NOT INCLUDE the platen knob, acoustic cover, and paper separator.
1.2.02 Weight
17.9 pounds (8.1 kilograms)
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)

Page: 5
Service Guide ML380
Chapter 1 Product Specifications
1.3 POWER REQUIREMENTS
1.3.01 Input Power
120 VAC: +5.5 / -15%
220/240 VAC: +5.5 / -15%
Single-phase AC
1.3.02 Power Consumption
Operating: 90 VA
Idle: 30 VA
1.3.03 Power Frequency
120 VAC: 50/60 Hz +/- 2%
220/240 VAC: 50/60 Hz +/- 2%
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)

Page: 6
Service Guide ML380
Chapter 1 Product Specifications
1.4 ENVIRONMENTAL CONDITIONS
1.4.01 Acoustic Rating
57 dBA
1.4.02 Altitude
10,000 feet (3,050 meters)
1.4.03 Ambient Temperature and Relative Humidity (RH)
While operating: 41 to 95 degrees Fahrenheit (5 to 35 degrees Celsius)
Operating humidity: 20% to 80% RH
While in storage: -40 to 158 degrees Fahrenheit (-40 to 70 degrees Celsius)
Storage humidity: 5% to 95% RH
1.4.04 Impact
Non-operating: 3 G or less
1.4.05 Vibration
Operating: 0.3 G (5 to 150 Hz) or less (except at resonating frequency)
Non-Operating: 1 G (5 to 150 Hz) or less (except at resonating frequency)
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)

Page: 7
Service Guide ML380
Chapter 1 Product Specifications
1.5 AGENCY APPROVALS
1.5.01 Listings
UL No: UL Standard No. 478 and 114
CSA No: CSA Standard C22.2 No. 154
FCC: FCC Certified per Part 15, Subject J, Class B
VDE: VDE 0806, 0875 Class B, and 0836
BS: BS 5850 / 6204
IEC: 435 / 380
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)

Page: 8
Service Guide ML380
Chapter 1 Product Specifications
1.6 OPERATIONAL SPECIFICATIONS
1.6.01 Character Matrix Sizes
Table of Print Speed and Character Matrix
Mode LQ Utility HS Utility
Speed 63 cps (12 cpi) 192 cps (12 cpi) 240 cps (15 cpi)
Matrix (H x V) 30 x 18 9 x 17 7 x 16
1.6.02 Characters Per Line
Maximum Characters Per Line Characters Per Inch
80 10
96 12
120 15
137 17.1
160 20
1.6.03 Character Pitches
5, 6, 8.5, 10, 12, 15, 17.1, 20 characters per inch
Characters Per Inch = cpi
The character pitches are selected through the following methods.
Operator panel (front panel controls)
Menu Select Mode (Menu Mode)
Control codes in the software
Special Microline 380 drivers
1.6.04 Character Sets
Standard ASCII
EPSON Character Set
IBM Character Set I and II
Foreign Language Sets (14)
Line Graphics
Zero / Slashed Zero
1.6.05 Emulation
Epson LQ
1.6.06 Fonts

Letter Quality
Courier
Letter Gothic
Prestige
Orator
Roman
Helvette
Draft
Utility
Special Font Effects
Emphasized / Enhanced
Outline
Shadow
Double Height
Double Width
1.6.07 Front Panel Switches
SELECT / Exit
FEED / Group
TOF / PARK / Item
FONT / Set
PITCH / Print
1.6.08 Graphics Resolution
Graphics Resolution
Maximum: 180 x 360 dpi
Minimum: 60 x 72 dpi
*1.6.09 Interface
Standard
Parallel
Optional
RS232C Serial, 19.2 Kbytes Super-Speed (Ready/Busy, X-ON / X-OFF)
NOTE:
When the serial interface module is installed, the printer's parallel interface connector is NOT accessible.
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/180 inch
1.6.11 Line Feed Time
2.2 inches per second
1.6.12 Menu Mode
Print: Prints the entire menu.
Group: Selects Group Function
Item: Selects Item
Set: Selects Item Value
Exit: Exits Menu Mode, Enters Select
1.6.13 Paper Feed Methods

Standard
Friction Feed (Top)
Push Tractor (Rear)
Optional
Pull Tractor (Bottom / Rear)
Single-Bin Cut Sheet Feeder (Top)
CSF 3800
1.6.14 Paper Feed Paths
Top Feed (Standard)
Rear Feed (Standard)
Bottom Feed (by using an Optional feed mechanism)
Special Features
Paper Park
Semi-Automatic Sheet Feeding
Paper Tear Off
1.6.15 Paper Loading
Semi-Automatic Sheet Feeding
Opening the paper bail arm activates the semi-automatic sheet feeder (SASF)
1.6.16 Paper Out Detection
Distance from end of paper
Rear Feed: 2.3 inches (57 millimeters)
Bottom Feed: 1.4 inches (36 millimeters)
Top Feed: 1 inch (25 mm)
1.6.17 Paper Tear Capabilities
Paper Tear-0ff (sharp edge on access cover)
1.6.18 Print Method
Printhead Type
General Information
Impact Dot Matrix
24 pin printhead
.0079 inch (.20 millimeter) diameter pins
Overheat Protection
When printhead temperature is between 90 and 129 degrees Celsius (ALARM 1), the printer stops
bi-directional printing. Uni-directional printing begins.
If the temperature continues to rise (130 degrees Celsius, ALARM 2), printing stops.
Printing will resume when the printhead temperature drops below the ALARM 1 threshold.
NOTE:
Refer to Section Two for more information on printhead operation.
Printhead Gap Information
Two 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 0.016, +/- 0.002 inches (0.41, +/- 0.05 mm).
2. Printhead Gap Adjust
The printhead gap is modified by moving the printhead gap lever, located on the left side of the housing.
To move the lever, pull it towards the printer housing and push the lever towards the front of the printer.
The settings are 1, 2, 3, 4, and 5.
Use 1 for single sheet.

Use 2 for multiple sheets or forms (thickness: 2 sheets).
Use 3 for multiple sheets or forms (thickness: 3 sheets).
Use 4 for multiple sheets or forms (thickness: 4 sheets).
Use 5 for envelopes and extra thick paper.
1.6.19 Print Modes
Letter Quality
Utility
1.6.20 Print Speed
Print
Mode Character Pitch
10 cpi 12 cpi 15 cpi 17.1 cpi 20 cpi
LQ 50 cps 60 cps 75 cps 85 cps 100 cps
Utility 150 cps 180 cps 112.5 cps 128.25 cps 150 cps
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)

Page: 9
Service Guide ML380
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
Length: 3 to 14 inches (76.2 to 356 millimeters)
Number of Copies: Original
Paper Feed Path: Bottom
Printhead Gap Information: Refer to the Printhead Gap Information, Section 1.6
Thickness: .008 inches (0.2 millimeters) Maximum
Weight: 100 lbs. (375 g/m 2 ) Maximum
Width: 5 to 8 inches (127 to 203 millimeters)
Continuous Form
Length: 3 to 14 inches (76.2 to 356 millimeters)
Number of Copies: Original, Original + 2 Interleaf Original + 2 Carbonless
Paper Feed Path: Rear or Bottom
Printhead Gap Information: Refer to the Printhead Gap Information, Section 1.6
Thickness: Single 0.0028 to 0.0039 inches (0.07 to 0.1 millimeters)
Multi 0.01 inch (.25 millimeter) Maximum
Weight:
Single Part 14 - 22 lb. (52.5 to 82.5 to 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: 3.5 to 10.5 inches (89 to 267 millimeters)
Cut Sheet
Number of Copies: Original, Original + 2 Interleaf Original + 2 Carbonless
Paper Feed Path: Top
Printhead Gap Information: Refer to the Printhead Gap Information, Section 1.6.
Note: Multi-part cut sheet paper CANNOT be used.
Weight: 14 to 22 lbs. (52.5 to 82.5 g/m 2 )
Width: 7.2 to 10 inches (182 to 254 millimeters)
Length: 3 to 14 inches (76.2 to 356 millimeters)
Thickness: 0.0028 to 0.0039 inches (0.07 to 0.1 millimeters)
Envelopes
Number of Copies: Original
Paper Feed Path: Bottom
Printhead Gap Information: Refer to the Printhead Gap Information, Section 1.6.
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: .016 inches (41 millimeters) Maximum
Weight: 17 to 24 lbs. (64 to 90 g/m 2 ) Maximum
Labels
Length: 3 to 14 inches (76.2 to 356 millimeters)

Number of Copies: Original
Paper Feed Path: Bottom
Printhead Gap Information: Refer to the Printhead Gap Information, Section 1.6.
Weight: N/A
Width: Carrier 3.5 to 8.5 inches (88 to 261 millimeters)
Thickness: .01 inches (0.25 mm) Maximum (including backing)
CAUTION:
Use Bottom Feed and/or optional Pull Tractor for card stock and labels.
DO NOT use fabric labels.
DO NOT print on the edge or perforation of the label.
DO NOT use Paper Park with labels.
Transparency
NOTE:
Roller marks may mar the transparency under high temperature / high humidity conditions.
Length: 3 to 14 inches (76.2 to 356 millimeters)
Number of Copies: Original
Paper Feed Path: Top
Printhead Gap Information: Refer to the Printhead Gap Information, Section 1.6.
Weight: 12 to 24 lbs. (45 to 90 g/m 2 )
Width: 8.5 to 11 inches (216 to 280 millimeters)
Thickness: 0.004 inches (0.1 millimeters)
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)

Page: 10
Service Guide ML380
Chapter 1 Product Specifications
1.8 MEMORY SPECIFICATIONS
1.8.01 EEPROM
256 Kbit EEPROM
Used to store Menu data
Located at Q18 of the main control board
1.8.02 ROM
Program ROM
256 Kbit
Located at Q2 of the main control board
Resident Character Generator ROM
1 Mbit
Masked to the CPU
1.8.03 RAM
32 Kbyte
Located on the main control board
Used as
Receive Buffer
Printer Buffer
Scratch Pad
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)

Page: 11
Service Guide ML380
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
Cartridge Fabric
Types
Black Nylon Ribbon
Life (On average, at 10 characters per inch, Utility Mode)
Black Ribbon 2 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)