Oki MICROLINE Turbo ML390 User manual

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Page: 1
Service Guide ML390/391
Chapter 0 About This Manual
ML390/ML391
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 ML390/391
0 About This Manual
Front Cover 1
Manual Copyright 2
1 Product Specifications
1.1 General Description - General Information 3
....1.1.02 Compatibility - Microline 390/391 vs. Microline
390/391-Plus 4
1.2 Product Specifications 5
1.3 Paper Specifications 6
1.4 Physical Specifications 7
1.5 Power Requirements 8
1.6 Environmental Requirements 9
1.7 Agency Approvals 10
1.8 Options 11
1.9 Consumables 12
1.10 Memory Specifications 13
1.11 Reliability Specifications 14
2 Principles of Operation
2.1 Printer Overview - General Information 15
....2.1.02 Compatibility - Microline 390/391 vs. Microline
390/391-Plus 16
2.2 Circuit Board Description 17
....Block Diagram (Microline 390/391) 18
....Block Diagram (Microline 390/391-Plus) 19
2.3 Electrical Operation - Initialization 20
....2.3.02 Interface Control 21
....2.3.03 Print Head Drive Circuit 22
....2.3.04 Spacing Operation 23
....2.3.05 Line Feed 24
....2.3.06 Alarm Circuits 25
2.4 Mechanical Principles Of Operation - Printhead 26
....2.4.02 Space Mechanism / Operation 27
........Head Gap Adjusting Mechanism 28
............Head Gap Adjusting Mechanism - Diagram 1 29
............Head Gap Adjusting Mechanism - Diagram 2 30
....2.4.03 Ribbon Drive Mechanism / Operation 31
....2.4.04 Paper Feed Mechanism 32
....2.4.05 Paper-End Detection Mechanism 33
....2.4.06 Semi-Automatic Sheet Feeder (SASF) Operation 34
....2.4.07 Release Lever Operation 35
3 Maintenance & Disassembly
3.1 Maintenance - General Information 36

Table of Contents Page
....3.1.02 Maintenance Tools 37
....3.1.03 Maintenance Precautions 38
3.2 Disassembly/Assembly Procedures 39
....3.2.01 Preliminary Items 40
....3.2.02 Separator Assembly 41
....3.2.03 Printhead Assembly 42
....3.2.04 Upper Cover Assembly 43
....3.2.05 Operator Panel Assembly 44
....3.2.06 Control Board - Revs A and B 45
........Control Board - Rev C 46
....3.2.07 IC Card (B) Panel 47
....3.2.08 Transformer - Revs A and B 48
........Transformer - Rev C 49
....3.2.09 Filter Assembly 50
....3.2.10 Power Supply Board - Revs A and B 51
........Power Supply Board - Rev C 52
....3.2.11 Power Interconnect Module / Cable Guide - Revs A
and B 53
........Power Interconnect Module / Cable Guide - Rev C 54
....3.2.12 Indicator Assembly (Bail Bar Assembly) 55
....3.2.13 Head Cable Access Cover and Connection Board
(SRBS) 56
....3.2.14 Ribbon Feed Gear Assembly 57
....3.2.15 Space Motor Assembly 58
....3.2.16 Carriage Frame Assembly 59
....3.2.17 Space Rack 60
....3.2.18 Guide Rail 61
....3.2.19 Platen Assembly 62
....3.2.20 Line Feed Motor and Gear - Line Feed Motor 63
........Line Feed Motor and Gear - Line Feed Motor Gear 64
....3.2.21 Line Feed Motor Interconnect Module 65
....3.2.22 Reset Spring, Change Gear, and Idler Gear 66
....3.2.23 Release Lever 67
....3.2.24 Paper Pressure Guide 68
....3.2.25 Pressure Roller Assembly 69
....3.2.26 Tractor Assembly 70
....3.2.27 Sensor Lever 71
....3.2.28 Paper End (B) Lever 72
....3.2.29 Main Chassis Assembly 73
3.3 Adjustments - General Information 74
....3.3.01 Printhead Gap Adjustment 75
3.4 Cleaning 76
3.5 Lubrication 77
4 Failure & Repair Analysis

Table of Contents Page
4.1 Overview - Introduction 78
....4.1.02 Compatibility - Microline 390/391 vs. Microline
390/391-Plus 79
4.2 Troubleshooting Updates 80
4.3 Reporting Problems 81
4.4 Troubleshooting Tips 82
4.5 Fault Alarms 83
4.6 Repair Analysis Procedures - Using The RAPS 84
....4.6.02 RAP Index 85
....4.6.03 Troubleshooting Cautions 86
........RAP 01: Operator Panel Lamps Do Not Light 87
........RAP 02: Abnormal Spacing 88
........RAP 03: Wrong or Missing Characters / Dots on Output 89
........RAP 04: Line Feed Problems 90
........RAP 05: Malfunction of Operator Panel Switch(es) 91
........RAP 06: Parallel Interface Does Not Receive Data 92
........RAP 07: Serial Interface Does Not Receive Data 93
4.7 Hexadecimal Dump 94
4.8 Resistance / Service Checks - Index To Charts 95
....4.8.02 Interconnect Diagrams - Microline 390/391 - Rev. A
and B 96
........Interconnect Diagrams - Microline 390/391 - Rev C 97
........Interconnect Diagrams - Microline 390/391 - Plus 98
....4.8.03 Printhead 99
....4.8.04 Space Motor 100
....4.8.05 Line Feed Motor 101
....4.8.06 Operator Panel Board 102
....4.8.07 Control Board 103
4.9 Printer Tests - General Information 104
....4.9.02 Rolling ASCII Print Test 105
....4.9.03 Font Sample Test 106
....4.9.04 Serial Interface Loopback Test 107
4.10 Menu Operation 108
4.11 Top Of Form 109
4.12 Paper Park 110
4.13 Forms Tear Off 111
A Board Diagrams
A.1 Board Reference Charts - General Information 112
....A.1.02 Compatibility - Microline 390/391 vs. Microline
390/391-Plus 113
A.2 Index To Charts - Microline 390/391: Rev A And B 114
....Index To Charts - Microline 390/391: Rev C 115
....Index To Charts - Microline 390/391 - Plus 116
....A.2.01 Control Board (SKRB) - Rev A and B 117

Table of Contents Page
....A.2.02 Control Board (SKRA) - Rev C and "Plus" Printers 118
....A.2.03 Power Supply (PAII) - Rev A and B 119
....A.2.04 Power Supply (SUII) - Rev C and "Plus" Printers 120
....A.2.05 Filter Assembly 121
....A.2.06 Operator Panel (LXSP) - Microline 390/391 122
....A.2.07 Operator Panel (LXSP-5) - Microline 390/391-Plus 123
....A.2.08 Interconnect Board (SRBS) 124
....A.2.09 RS232-C Serial Interface (LXHI) 125
B Illustrated Parts Listing
B.1 Illustrated Parts Listing - General Information 126
....B.1.02 Definitions of Terms 127
....B.1.03 Compatibility - Microline 390/391 vs. Microline
390/391-Plus 128
....B.1.04 Parts Ordering Information 129
B.2 Charts - Index 130
....B.2.01 Covers 131
....B.2.02 Electrical Components - Rev A and B 132
....B.2.03 Electrical Components - Rev C 133
....B.2.04 Printer Mechanism - Rev A and B (1 of 2) 134
....B.2.05 Printer Mechanism - Rev A and B (2 of 2) 135
....B.2.06 Printer Mechanism - Rev C (1 of 2) 136
....B.2.07 Printer Mechanism - Rev C (2 of 2) 137
....B.2.08 Operator Panel 138
....B.2.09 Carriage Assembly 139
....B.2.10 Tractor Assembly 140
....B.2.11 Options 141
....B.2.12 Consumables 142
....B.2.13 Packaging 143
....B.2.14 Documentation 144

Page: 2
Service Guide ML390/391
Chapter 0 About This Manual
This document may not be reproduced without 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 our control.
© 1994 by Okidata All rights reserved.
First Edition April, 1994
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.
Centronics is a registered trademark of Centronics Inc.
IBM is a registered trademark of International Business Machines, Inc.
Proprinter is a registered trademark of International Business Machines, Inc.
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 ML390/391
Chapter 1 Product Specifications
1.1 GENERAL DESCRIPTION
1.1.01 General Information
The Microline 390, Microline 391, Microline 390-Plus, and 391-Plus are twenty-four pin, dot matrix printers.
These printers provide Epson LQ and IBM Proprinter emulations, which are selected through the Printer
Menu.
The major difference between the Microline 390/390-Plus and Microline 391/391-Plus is the width of each
printer. The Microline 390/390-Plus can handle 80 print columns (at 10 CPI). The Microline 391/391-Plus
can print up to 136 columns (at 10 CPI).
The standard interface is a Centronics parallel and an optional RS232-C serial interface can be installed.
The optional serial interface can transfer data at speeds up to 19.2K baud.
Both printers feature an enhanced operator panel which provides access to the following capabilities.
· Menu Selection
· Quiet Mode
· Printer Tests
· Paper Park
· Print Characteristics
· Standard Printer Controls
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 ML390/391
Chapter 1 Product Specifications
1.1.02 Compatibility - Microline 390/391 vs. Microline 390/391-Plus
The differences between the Microline 390/391 and Microline 390/391-Plus printers are listed below.
Hardware Differences
· Operator Panel
· Operator Board
· Character Generator Programmable Read Only Memory (CGROM)
· Programmable Read Only Memory (PROM)
· Middle Cover
Operational Differences
· "Plus" printers have more resident fonts.
· In the "Plus" printers, data in the receive buffer is printed upon receipt, without having to wait for a line
terminator character (CR/LF or FF).
· In the "Plus" printers, the DC1/DC3 Acknowledge/Ignore, Receive Buffer Size, and RESET inhibit can be
controlled through the printers Menu.
Serial Number Revision Levels
Microline 390/391
A
Rev A units are original production units. An interconnect module connects the power supply board to the
main control board.
B
Rev B units are retrofitted to include a modified interconnect module, which prevents corrosion.
C
These units have a cable connection between the power supply board and the main control board. The
cable connection wire replaces the interconnect module.
Microline 390/391-Plus
Revision levels do NOT apply to the "Plus" printers.
NOTE:
Please refer to the parts lists for parts differentiation. Please be sure of the parts you need before ordering
to avoid confusion and incorrect parts orders.
Printer Serial Number Identification
There are three serial number revision levels for the printers. Hardware differences exist between levels.
To identify the revision level of a printer, record the serial number from the back of the printer. Refer to the
following to decode the serial number.

Example Printer Serial Number: 401A0154693
Date Code 401 (4 = year. 01 = month)
Revision A
Serial Number 0154693
Compatibility Chart
Item Okidata
P/N Purpos e /
Functio
n of
Item
Printer
Serial
Number
Revision
Level
390/391A 390/391B 390/391C 390+ 391+
Main
Control
Board
SKRA
Board 5504540 1Main Control
Board
Yes Yes No No No
SKRB
Board 5503870 2Main Control
Board
Yes Yes Yes No No
SKRA-3
Board 5504540 3Main Control
Board
Yes Yes Yes Yes Yes
Power
Supply
Board
PAII
Board 5503880 1Power Supply
Board
Yes Yes No No No
SUII
Board 5504740 1Power Supply
Board
Yes Yes Yes Yes Yes
Operator
Panel
Assembl
y

Panel:
Operator
Assembly
5006960
1Operato r Panel
Assemb
ly
(390/39
1)
Yes Yes Yes No No
Panel:
Operator
Assembly
5006961
0Operato r Panel
Assemb
ly
(390/39
1-Plus)
No No No Yes Yes
PCB:
LXSP 5504560 1Operato r Panel
Board
(390/39
1)
Yes Yes Yes No No
PCB:
LXSP-5 5503860 5Operato r Panel
Board
(390/39
1-Plus)
No No No Yes Yes
Transfor
mer
120 Volt
XFRMR 5640720 1Transfo rmer
(390
and
390-Plu
s)
Yes Yes Yes Yes Yes
120 Volt
XFRMR 5640720 2Transfo rmer
(391
and
391-Plu
s)
Yes Yes Yes Yes Yes
220 Volt
XFRMR 5640780 1Transfo rmer
(390
and
390-Plu
s)
Yes Yes Yes Yes No

220 Volt
XFRMR 5640780 2Transfo rmer
(391
and
391-Plu
s)
Yes Yes Yes No Yes
Intercon
nect
Module
Interconn
ect
Module
5532830
1Connec ts
power
supply
board
to main
board
Yes Yes No No No
Cable
Cable 5661680
2Connec ts
power
supply
board
to main
board
No No Yes Yes Yes
Cable
Guide
Cable
Guide 5100380 1Holds cable in
place
No No Yes Yes Yes
Covers
Cover 5348830
1Middle Cover
(390)
Yes Yes Yes No No
Cover 5348840
1Middle Cover
(391)
Yes Yes Yes No No

Cover 5348831
6Middle Cover
(390-Pl
us)
No No No Yes No
Cover 5348842
2Middle Cover
(391-Pl
us)
No No No No Yes
Chassis
Chassis 5006110
1Chassis : Main
(390
and
390-Plu
s)
Yes Yes Yes Yes No
Chassis 5006120
1 Chassis
: Main
(391
and
391-Plu
s)
Yes Yes Yes No Yes
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 ML390/391
Chapter 1 Product Specifications
1.2 PRODUCT SPECIFICATIONS
1.2.01 Print Method
· Impact Dot Matrix
Number of Print Wires: 24
Print Wire Diameter: .0079 inch (.2 mm)
1.2.02 Print Modes
· Utility
· Letter Quality (LQ)
1.2.03 Character Pitches
· 10 CPI
· 12 CPI
· 15 CPI
· 17.1 CPI
· 20 CPI
· Proportional
1.2.04 Character Sets
· Standard ASCII
· Epson Character Set
· IBM Character Set I
· IBM Character Set II
· IBM Proprinter Compatible Character Set
· Foreign Language Substitution
· Line Graphics
NOTES:
Characters Per Inch = cpi Characters Per Second = cps Dots Per Inch = dpi
Character Sets are selected through the Menu
1.2.05 Resident Fonts
Microline 390/391
· Courier
· Utility
NOTE:

Additional fonts can be accessed by using an optional font card.
Microline 390/391-Plus
· Courier
· Roman
· Swiss
· Orator
· Gothic
· Prestige
· Utility
NOTE:
Additional fonts can be accessed by using an optional font card.
The "Plus" printers can access Down Line Loadable (DLL) fonts.
1.2.06 Print Speed
Print Mode Character
Pitch
10 cpi 12 cpi 15 cpi 17.1cpi 20 cpi
Utility 225 cps 270 cps 168.6 cps 192.9 cps 225 cps
LQ 75 cps 90 cps 112.5 128.6 cps 150 cps
1.2.07 Print Resolution
Print Mode Character
Pitch
10 cpi 12 cpi 15 cpi 17.1cpi 20 cpi
Utility 120 dpi 120 dpi 240 dpi 240 dpi 240 dpi
LQ 360 dpi 360 dpi 360 dpi 360 dpi 360 dpi
1.2.08 Character Matrix Sizes

Print Mode Matrix Size Characters Per Inch
Utility 9 X 7 All sizes
LQ 17 X 13 10 and 12 cpi
LQ 15 X 18 15 17.1 and 20 cpi
1.2.09 Characters Per Line
10 CPI 12 CPI 15 CPI 17.1 CPI 20 CPI
390/390-Plus 80 96 120 137 160
391/391-Plus 136 163 204 233 272
1.2.10 Paper Feed Specification
Available Paper Paths
· Rear
· Top
· Bottom Feed
NOTE:
Bottom Feed requires the use of the optional pull tractor
Line Feed Increments
· 1/6", 1/8", n/60", n/180", n/216" and n/360".
Line Feed Timing
· 70 ms @ 6 lines per inch
· Slew Rate: 3.75 inches per second (Continuous Feed Paper)
1.2.11 Interface Specifications
· Centronics Parallel (Standard)
· RS232C Serial (Optional)
NOTE:
Interface cables are sold separately.
A shielded cable is required. Twisted-pair wires are recommended for noise protection.
Parallel interface cables should be no more that 16.4 feet (5 m) in length.

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 ML390/391
Chapter 1 Product Specifications
1.3 PAPER SPECIFICATIONS
1.3.01 Width
· Microline 390/390-Plus
Minimum: 3 inches (76.2 mm)
Maximum: 10 inches (254 mm)
· Microline 391/391-Plus
Minimum: 3 inches (76.2 mm)
Maximum: 16 inches (406.4 mm)
1.3.02 Single Part Forms
· Weight
Minimum: 12 pound (45 g/m 2 )
Maximum: 24 pound (90 g/m 2 )
1.3.03 Multipart Forms - Carbon Lined or Pressure Sensitive
· Weight
Minimum: 9 pound (35 g/m 2 )
Maximum: 11 pound (40 g/m 2 )
· Thickness
Maximum: 0.014 inches (0.356 mm)
· Number of Copies
Original plus three copies
1.3.04 Multipart - Interleaf
· Weight
Paper
Minimum: 10 pound (38 g/m 2 )
Maximum: 12 pound (45 g/m 2 )
Carbon
Maximum: 9 pound (35 g/m 2 )
· Thickness
Maximum: 0.014 inches (0.356 mm)
· Number of Copies
Original plus three copies

1.3.05 Cut Sheets (Single Part ONLY)
· Friction Feed
Weight
Minimum: 12 pound (45 g/m 2 )
Maximum: 24 pound (90 g/m 2 )
· Cut Sheet Feeder 3000
Weight
Minimum: 16 pound
Maximum: 24 pound (90 g/m 2 )
1.3.06 Envelopes (Individual)
· Weight
Maximum: 24 pound maximum (90 g/m 2 )
· Thickness
Maximum: 0.016 inches (0.41 mm)
· Dimensions
6 1/2 inches x 3 5/8 inches
8 7/8 inches x 3 7/8 inches
9 1/2 inches x 4 1/8 inches
1.3.07 Envelopes (Continuous)
NOTES:
Continuous Feed Envelopes should be used ONLY with bottom feed.
· Weight
Maximum: 24 pound (90 g/m 2 )
· Thickness
Maximum: 0.014 inches (0.36 mm)
· Width
Minimum: 3 inches (76.2 mm)
Maximum: 10 inches (354 mm)
1.3.08 Card Stock
NOTES:
Card Stock should be used ONLY with bottom feed.
Set the head gap adjusting lever for optimum printing performance.
· Weight
Maximum: 100 pound (150 g/m 2 )
· Thickness
Maximum: 0.008 inches (0.20 mm)

· Dimensions
Maximum: 5 inches x 8 inches
1.3.09 Labels
NOTES:
Labels should be used ONLY with bottom feed.
Do NOT use fabric labels.
Do NOT print on the edge or perforation of the label.
· Carrier Width
Maximum: 8.5 inches (216 mm) Microline 390/390-Plus
Maximum: 15 inches (381 mm) Microline 391/391-Plus
· Thickness
Maximum: 0.011 inches (0.28 mm)
1.3.10 Transparencies
· Thickness
Maximum: 0.004 inches (0.10 mm)
· Dimensions
Maximum: 8.5 inches wide x 11 inches long (216 mm x 260 mm)
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)