59348301_b.p65 ML420 Oki Data Microline 420 Printer Manual

ML420 to the manual a5699021-3b50-e5e4-251a-5cab55df8f85

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User Manual: ML420

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User’s
Guide

59348301

ML 420/421 User’s Guide
P/N 59348301, Revision 1.2
February, 2006
Every effort has been made to ensure that the information in
this document is complete, accurate, and up-to-date. Oki Data
assumes no responsibility for the results of errors beyond its
control. Oki Data also cannot guarantee that changes in
software and equipment made by other manufacturers and
referred to in this guide will not affect the applicability of the
information in it. Mention of software products manufactured
by other companies does not necessarily constitute
endorsement by Oki Data.
Copyright 2002, 2007 by Oki Data. All rights reserved.
Written and produced by the Oki Data Training and
Publications Department.
Web Site: http://www.okiprintingsolutions.com.

Trademark Information
OKI and MICROLINE are registered
trademarks of Oki Electric Industry
Company, Ltd.
Epson is a registered trademark of Epson America, Inc.
IBM is a registered trademark of International Business Machines
Corp.
Microsoft and Windows are either registered trademarks or
trademarks of Microsoft Corporation in the United States and
other countries.

Safety
Your Oki printer has been carefully designed to give you years
of safe, reliable performance. As with all electrical equipment,
there are a few basic precautions you should take to avoid
hurting yourself or damaging the printer:
• Carefully read all setup and operating instructions. Be sure
to save all documents for future reference.
• Read and follow all warning and instruction labels on the
printer itself.
• Place your printer on a firm, solid surface. If you put in on
something unsteady, it might fall and be damaged.
• Avoid overheating the printer. Do not place it on a soft
surface, such as a rug, sofa, or bed. The vents may be
blocked, causing the printer to overheat.
• The printer must be installed near a power outlet which will
remain easily accessible.

• Be certain that your power source matches the rating listed
on the back of the printer. If you aren’t sure, check with your
dealer or with your local power company.
• Your printer has a grounded, 3-prong plug as a safety feature.
It will only fit into a grounded outlet. If you can not plug it
in, chances are that you have an older, non-grounded outlet.
Contact an electrician to have it replaced with a grounded
outlet. Do not use an adapter to defeat the grounding.
• To avoid damaging the power cord, do not put anything on it
or place it where it will be walked on. If the cord becomes
damaged or frayed, replace it immediately.
• If you’re using an extension cord or power strip with the
printer, make sure that the total of the amperes required by all
the equipment on the extension is less than the extension’s
rating. Generally, the total ratings of all equipment plugged
into any one power line should not exceed 15 amperes. Don’t
exceed this unless you know that the power line your
equipment is plugged into has a rating above 15 amperes.

• Unplug the printer before you clean it. Use only a damp
cloth. Do not use liquid or aerosol cleaners.
• To protect your printer from overheating, make sure no
openings on the printer are blocked. Do not put the printer on
or near a heat source, such as a radiator or heat register. If
you put the printer in any kind of enclosure, make sure it is
well ventilated.
• The printhead can get quite hot when it has been printing for
a length of time. Do not touch the printhead until it has had a
chance to cool off.
• Do not use your printer near water. Do not spill liquid of any
kind into it.
• Do not poke anything into the ventilation slots on the sides of
the printer. You could get a shock or cause a fire.
• Aside from the routine maintenance described in this
document, don’t try to service the printer yourself. Opening
the cover may expose you to shocks or other hazards. Don’t
make any adjustments other than those outlined in the
document. You might cause damage requiring extensive
repair work.

4 Microline 420/421 User’s Guide

• If anything happens that indicates that your printer is not
working properly or has been damaged, unplug it
immediately. Then, follow the procedures in “Service and
Support” for having your printer serviced.
These are some of the things to look for:
– The power cord or plug is frayed or damaged.
– Liquid has been spilled into the housing, or the printer has
been exposed to water.
– The printer has been dropped or its cabinet has been
damaged.
– The printer doesn’t function normally when you’re
following the operating instructions.

Contents
Safety............................................................................ 3
Chapter 1: Introduction ............................................. 7
Printer Features ............................................................................... 7

Chapter 2: Helpful Hints ........................................... 8
Saving Money: Forms Tear-Off ...................................................... 8
Saving Time .................................................................................... 8
Internet Support ........................................................................... 8
Paper Park .................................................................................... 8
Operation Tips ................................................................................ 9
Top of Form (TOF) ...................................................................... 9
Turning the Platen Knob .............................................................. 9
Controlling Access to the Printer ................................................. 9

Chapter 3: Using Your Printer ................................ 10
Parts Identification: Rear Feed (Continuous Forms) .................... 10
Parts Identification: Top Feed (Single Sheets) ............................. 11

Top of Form (TOF) ....................................................................... 12
Top of Form (TOF) and Forms Tear-Off .................................... 12
Determining if Forms Tear-Off is Off or On .............................. 13
Setting Top of Form (TOF):
Forms Tear-Off OFF (Default Setting) ...................................... 14
Setting Top of Form (TOF):
Forms Tear-Off Set to ON .......................................................... 15
Temporarily Changing the Top of Form Position ...................... 16
Resetting Top of Form to the Factory Default ........................... 16
Forms Tear-Off Feature ................................................................ 17
Potential Problems with Software Packages .............................. 17
Changing the Forms Tear-Off Setting ........................................ 18
Manual Forms Tear Off .............................................................. 18
Paper Park ..................................................................................... 18
Changing Paper Paths ................................................................... 19
Printhead Gap ............................................................................... 21
Print Quality ................................................................................. 22
Character Pitch ............................................................................. 23
Printer Reset ................................................................................. 24
Emulations .................................................................................... 24

Chapter 4: Menu Mode ............................................ 25

Appendix B: Printer Control Codes ....................... 69

Menu Mode Keys ....................................................................... 25
Entering and Exiting Menu Mode ............................................. 26
Resetting the Menu to the Factory Defaults .............................. 26
Printing the Menu Settings ......................................................... 26
Changing the Menu Settings ...................................................... 27
Menu Settings Table ................................................................... 28
Explanations of Menu Items ...................................................... 35

IBM Proprinter III Commands ..................................................... 69
Epson FX Commands ................................................................... 72
Oki MICROLINE Standard Commands ...................................... 75

Chapter 5: Maintenance........................................... 42
Replacing the Ribbon Cartridge ................................................... 42
Loading Paper ............................................................................... 44
Rear Feed ................................................................................... 44
Top Feed (Single Sheets) ........................................................... 53
Clearing Paper Jams ..................................................................... 55
Rear-Feed Paper Jams ................................................................ 55
Rear-Feed, Repeating Paper Jams .............................................. 56
Single-Sheet Paper Jams ............................................................ 58
Cleaning the Housing ................................................................... 59

Chapter 6: Troubleshooting ..................................... 60
General Information ..................................................................... 60
Problems / Solutions ..................................................................... 61

Appendix A: Parts & Accessories ............................ 66
Purchasing Parts & Accessories ................................................... 66
Replacement Parts ........................................................................ 67
Accessories ................................................................................... 68
6 Microline 420/421 User’s Guide

Appendix C: Specifications ...................................... 78
Appendix D: Installation .......................................... 84
Location ........................................................................................ 84
Unpack .......................................................................................... 84
Install the Ribbon Cartridge ....................................................... 87
Power Connection ........................................................................ 88
Computer Connections ................................................................. 88
Parallel (LPT): IEEE 1284 ......................................................... 88
USB: Specification 1.1 Compliant ............................................. 89
Loading Paper ............................................................................... 89
Testing the Printer ......................................................................... 90
Font Sample Test ........................................................................ 90
Rolling ASCII Test ..................................................................... 91
Hexadecimal Dump Mode ......................................................... 92
Emulations .................................................................................... 92
Printer Drivers .............................................................................. 92
Loading the OKI Driver ............................................................. 93
Using a Compatible Driver ........................................................ 93

Index .......................................................................... 94

Chapter 1: Introduction
Printer Features

Oki Data on the Internet

• Super reliable, durable operation: 20,000 hours Mean Time
Between Failures (MTBF) at 25% duty cycle and 35% page
density
• Advanced paper handling, with built-in rear push tractor and
zero-tear forms capability.
• Blazing print speeds, in characters per second:
– High Speed Draft (HSD) Mode: 507 cps
– Utility Mode: 380 cps
– Near Letter Quality (NLQ) Mode: 95 cps

The Oki Data Web Sites provide the most current information
available on your printer.
On-line documents are available for viewing and downloading
via Oki Data’s Web Sites.
You may reach Oki Data via the Internet at:
• www.okidata.com
• my.okidata.com

– Super Speed Draft (SSD) Mode: 570 cps
• This rugged 9-pin printer can meet the needs of harsh and
demanding environments.

Chapter 2: Helpful Hints
Saving Money: Forms Tear-Off

Saving Time

The Forms Tear-Off feature allows a printed continuous forms
page to be torn off without wasting paper or adjusting the
printer.

Internet Support

When printing stops, Forms Tear-Off automatically moves the
paper to align the perforation with the tear bar (located under
the access cover), after a time interval which you select through
the menu.

• www.okidata.com is the main web site, the gateway to Oki
Data’s products and services.
• http://my.okidata.com is a powerful area of Oki Data’s web
site designed to help you personalize the information and
service you get from Oki Data.

Paper remains in the tear-off position until the printer receives
more data. Then, the paper moves back down for printing.
Note: This feature is normally turned off.
Important!
Forms Tear-Off and the Top of Form settings interact. For
more information, see “Top of Form (TOF) and Forms TearOff” in Chapter 3.

Oki Data provides support via the Internet:

Paper Park
Your printer’s paper park feature allows you to print a single
sheet (cut-sheet) page without removing continuous feed paper
from the printer.
For more information, see “Paper Park” in Chapter 3.

Operation Tips
Top of Form (TOF)
Top of Form (TOF) sets the print start position. The factory
default is 1" from the top.
The Top of Form can be changed in increments of 1/180",
either for a single print job or set to a new default. The overall
amount of adjustment is limited to avoid paper jams.
The first line prints at the red line of the plastic paper shield (1)
on the printhead.

Turning the Platen Knob
Important!
Always turn the printer off before turning the platen knob! If
you turn the platen knob when the printer is on, the Top of
Form misaligns.

Controlling Access to the Printer
You can control access to the printer by changing the setting for
the Operator Panel Function in the Menu from Full Operation
(the factory default) to Limited Operation.
When Limited Operation is selected, the PRINT QUALITY and
CHARACTER PITCH keys don’t work. This prevents these
settings from being changed from the control panel when
several people are using the printer.
For more information, see “Changing the Menu Settings” in
Chapter 3.

For more information, see “Top of Form (TOF)” in Chapter 3.

Helpful Hints 9

Chapter 3: Using Your Printer
Parts Identification: Rear Feed
(Continuous Forms)
Note: The serial number of your printer is on a label on the
back, beside “S/N.”
Sheet Guide
Paper Lever
On-Off Switch
Platen Knob
Control Panel
Acoustic Cover
Access Cover

Note: For rear feed, the paper lever must be forward.

Parts Identification: Top Feed
(Single Sheets)

Note: For single-sheet printing, the paper lever must be in the
middle position.

Paper Guides
Sheet Guide
Paper Lever
On-Off Switch
Platen Knob
Control Panel
Acoustic Cover (open)

Using Your Printer 11

Top of Form (TOF)

Top of Form (TOF) and Forms Tear-Off

Important!
If you turn the platen knob when the printer is on, the Top of
Form misaligns. Always shut the printer off before turning
the platen knob!

Note: Your software may print the first line of print above or
below where TOF is set. You may need to adjust the
TOF to meet your software’s requirements.

Note: The factory default setting for the Top of Form (where
the printing should begin) is 1" down from the top of the
page.
Top of Form sets the print start position for the printer. It is
adjustable in increments of 1/144 of an inch. The amount of
adjustment is limited to avoid paper jams.
The first line prints at the red line of the plastic paper shield (1)
on the printhead.

12 Microline 420/421 User’s Guide

The Top of Form and Forms Tear-Off settings of your printer
interact. How you set the Top of Form depends on whether
Forms Tear-Off is On (set to 500 ms, 1 sec, or 2 sec) or OFF
(the factory default setting).

Determining if Forms Tear-Off is Off or On

To use the TEAR key:

There are two ways to determine the status of the Forms
Tear-Off menu setting:

1 Make sure paper is loaded.
2 Press TEAR (3).
• If the paper moves up, Forms Tear-off is off.
• If the paper moves down, Forms Tear-off is on.

• Print the Menu.
• Use the TEAR key.

To print the Menu:

1
2
3
4

Make sure paper is loaded.
Hold SHIFT (2), then press SEL (1) to enter the Menu Mode.
Press PARK (4) to print the menu.
Look for the Form Tear-Off setting in the paper feed group
you are using (Rear Feed, Bottom Feed or Top Feed—Forms
Tear–Off appears in the Top Feed group only if the optional
Roll Paper Stand is installed).

Using Your Printer 13

Setting Top of Form (TOF):
Forms Tear-Off OFF (Default Setting)
Important!
If you turn the platen knob when the printer is on, the Top of
Form misaligns. Always turn the printer off before turning
the platen knob!

With paper loaded and the printer on and selected:
1 Press SEL | MENU (1) to take the printer off line.
The SEL light goes out.
2 Press and hold SHIFT (2), then
Note: When you begin pressing the Micro Feed key, the
printhead will move to the right.
• Press LF | Micro Feed Down (3) to set the TOF higher (the
paper moves down).
• Press FF/LOAD | Micro Feed Up (4) to set the TOF lower
(the paper moves up).

Note: The first line prints at the red line (1) of the plastic
paper shield on the printhead.

3 When you have the TOF set where you want it, press and
hold SHIFT (2), then press QUIET/TOF (7) to engage the new
setting.
The printhead moves back to the left margin.
4 Press SEL/MENU (1) to save the setting and place the printer
back on line.
Note: To reset the Top of Form to the factory default, see
“Resetting Top of Form to the Factory Default” later in
this chapter.

14 Microline 420/421 User’s Guide

Setting Top of Form (TOF):
Forms Tear-Off Set to ON
Important!
If you turn the platen knob when the printer is on, the Top of
Form misaligns. Always turn the printer off before turning
the platen knob!

2 Press SHIFT (2) and QUIET/TOF (7) to reset the current TOF.
3 Press FF/LOAD (4) to load the paper.
4 Wait briefly until the paper moves up to the tear position,
then press and hold TEAR (5).
The paper moves to the current TOF.
5 Keep holding TEAR, then press and hold SHIFT (2) and
release TEAR.
6 Continue to hold SHIFT, then
Note: When you begin pressing the Micro Feed key, the
printhead will move to the right.

Note: The first line prints at the red line (1) of the plastic
paper shield on the printhead.

• Press LF | Micro Feed Down (3) to set the TOF higher (the
paper moves down).
• Press FF/LOAD | Micro Feed Up (4) to set the TOF lower
(the paper moves up).

With paper loaded and the printer on and selected:

7 When you have the TOF set where you want it, press and
hold SHIFT (2), then press QUIET/TOF (7) to engage the new
setting.
The printhead moves back to the left margin.
8 Press SEL/MENU (1) to save the setting and place the printer
back on line.

1 Press PARK (6) to park the paper.
The SEL light goes off and the red alarm light comes on.

Note: To reset the Top of Form to the factory default, see the
next page.

Using Your Printer 15

Temporarily Changing the Top of Form
Position
Important
Do not use the platen knob to change the Top of Form. If you
turn the platen knob when the printer is turned on, the Top of
Form misaligns. Always turn the printer off before turning
the platen knob!
To move the Top of Form position lower for one page only:
1 Press SEL to deselect the printer.
2 Press LF to lower the position of the Top of Form.

16 Microline 420/421 User’s Guide

Resetting Top of Form to the Factory Default
The factory default setting for the Top of Form (where the
printing should begin) is 1" down from the top of the page.
To reset the Top of Form to the factory default:
1 Remove paper from the paper path.
2 Turn the printer off.
3 Press and hold PARK + QUIET/TOF while turning on the
printer.
4 Reload paper.

Forms Tear-Off Feature
Note: This feature is normally turned off. To use Forms
Tear-Off, you must enter the menu and change the
setting to the desired time interval (see next page).
The Forms Tear-Off feature allows a printed continuous forms
page to be torn off without wasting paper or adjusting the
printer. It can be used for rear feed continuous forms, bottom
feed continuous forms (with the optional push tractor installed)
or for top feed roll paper (with optional roll paper stand
installed).
When the printer is turned on, the paper feeds to the tear-off
position.
When data is received, the paper automatically moves down to
the print position (TOF) and printing begins.
Note: You can also move the paper down to the print position
manually by pressing TEAR.

Notes: The status of the Forms Tear-Off menu setting affects
how you set the Top of Form: see “Top of Form (TOF)
and Forms Tear-Off” earlier in this chapter.
Do not use Forms Tear-Off with labels or multipart
forms!
Forms Tear-Off cannot be used when the optional pull
tractor is engaged.

Potential Problems with Software Packages
If Forms Tear-Off is set to On and the software package you are
using “pauses” for a long enough interval while sending data to
the printer, Forms Tear-Off may be activated. No data is lost,
but this causes uneven print registration due to the paper
movement.
If this occurs, use the menu to turn off this feature, then use the
TEAR key to move the paper up to the tear position manually
(see next page).

When printing stops, Forms Tear-Off automatically moves the
paper to align the perforation with the tear bar (located under
the access cover), after the time interval which you selected
through the menu.
Paper remains in the tear-off position until the printer receives
more data. Then, the paper moves back down for printing.

Using Your Printer 17

Changing the Forms Tear-Off Setting

Manual Forms Tear Off

Note: The default setting for Forms Tear-Off is OFF.

If you don’t wish to engage the Forms Tear-Off feature, you
can advance
• rear-feed continuous forms loaded on the built-in tractor
or
• bottom-feed continuous forms loaded on the optional push
tractor
up to the tear off position manually by pressing TEAR (5).

Paper Park

To change the Forms Tear-Off setting:
1 Press SHIFT (2) + SEL (1).
2 Press GROUP (3) repeatedly until the Rear Feed or Bottom
Feed group shows in the first column of the printed line,
depending on which paper feed you are using,
3 Press ITEM (4) repeatedly until Form Tear-Off appears in the
second column:
Rear Feed

Form Tear-Off

Off

4 Press SET (5) until the time interval you wish to select
appears in the third column:
Rear Feed

Form Tear-Off

1 Sec

5 Press SHIFT (2) + SEL (1) to exit Menu Mode and save the
setting.
18 Microline 420/421 User’s Guide

Important!
Never park labels!
Paper park allows you to switch to single-sheet printing without
removing continuous feed paper from the printer.
When you wish to print single sheets, simply press PARK (6) to
retract the continuous form paper from the paper path, then lift
the sheet guide, load the sheet and send the print job.

Changing Paper Paths

4 Move the paper lever (1) to the middle position marked
“TOP.”

Continuous Forms to Single Sheets
1 Tear off any printed pages, then press PARK.
2 Raise the sheet guide (1) to the single-sheet feed position.

5 Adjust the paper guides (1) for the size paper you are using,
then place a sheet of paper in the sheet guide.

3 Pivot the wire feed guide into the sheet guide.

Using Your Printer 19

Single Sheets to Continuous Forms
1 Press FF/LOAD to remove the single-sheet paper.
2 Lower the sheet guide into the continuous-forms position.

4 Move the paper lever to the appropriate position.
• Rear feed:

• Bottom feed:

3 Swing the wire feed guide over onto the pull-up roller.

5 If necessary, load continuous-form paper.
6 Press FF/LOAD.

20 Microline 420/421 User’s Guide

Printhead Gap
The printhead gap is the distance between the printhead and the
platen.

To adjust the gap, open the access cover and move the blue
lever (1) to the recommended setting from the table.

CAUTION!
Make sure the printer is turned off before you open the access
cover.

Setting

Media

Regular paper

2-part form (with carbon)

3-part form (with carbon)

4-part form (with carbon)

Envelopes or extra thick paper

Note: When the head gap is set to 2, 3, 4 or 5, the printer
automatically slows down for better print quality with
multipart forms.

Using Your Printer 21

Print Quality
Important!
Front panel settings for print quality and character pitch are
normally overridden by software commands.

HSD: High Speed Draft

• Lower quality, higher speed (507 cps)
• Gothic typeface only
SSD: Super Speed Draft

• Lowest quality, highest speed (570 cps)
• Gothic typeface only
NLQ: Near Letter Quality

• Highest quality, slowest speed (95 cps)
• Courier or Gothic
Press PRINT QUALITY (1) to select:
UTL: Utility—the default

• Medium quality, medium speed (380 cps)
• Gothic typeface only

22 Microline 420/421 User’s Guide

Character Pitch
Important!
Front panel settings for character pitch are normally
overridden when the SI command is received from your
software.

Epson and IBM Emulations
Set the character pitch by pressing CHARACTER PITCH (1)
until the light beneath the desired setting is lit:
•
•
•
•
•
•

10 cpi
12 cpi
15 cpi
17 cpi
20 cpi
Proportional

MICROLINE Emulation
In the MICROLINE emulation, the Character Pitch choices are:
Character pitch determines how many characters will print on
each line. You can choose a specific fixed width for each
character in characters per inch (CPI), or Proportional. The
higher cpi settings are often used for spreadsheets.
Proportional (PROP) sets character widths based on the
character itself: e.g., the letter i is assigned a narrower width
than the letter m. This provides a more polished, typeset
appearance.
Note: To reset the printer to the factory default character
pitch, deselect the printer, then press and hold the
SHIFT key while pressing the CHARACTER PITCH key.

•
•
•
•
•

10 cpi, Proportional or non-proportional
12 cpi, Proportional or non-proportional
15 cpi, Proportional or non-proportional
17 cpi, Proportional or non-proportional
20 cpi, Proportional or non-proportional

To select Proportional, press the CHARACTER PITCH key until
both the cpi value and PROP lights are lit.
To select non-proportional, press the CHARACTER PITCH key
until the light for the cpi value you wish to use is lit.

Using Your Printer 23

Printer Reset

Emulations

Clearing some error conditions requires that you reset
(reinitialize) the printer. To do this:

• IBM® Proprinter III — factory setting
• Epson® FX
• Oki® MICROLINE®

1 Press and release SEL (1) to take the printer off-line.
The SEL light goes out.
2 Press and hold SHIFT (2), then press the RESET/
CHARACTER PITCH key.
Important!
Pressing SHIFT + RESET reinitializes the printer, but does not
affect any menu settings and does not reset the printer to the
factory defaults. For information on resetting the printer to
the factory defaults, see “Resetting the Menu to the Factory
Defaults” later in this chapter.

24 Microline 420/421 User’s Guide

Changing Emulations
1 Make sure paper is loaded.
2 Press and hold SHIFT (2), then press SEL (1).
3 Press LF (3).
The following line prints:
Printer Control

Emulation Mode

IBM PPR

4 Press TEAR (4) repeatedly until the emulation you wish to
select prints in the right-hand column.
5 Press and hold SHIFT (2), then press SEL (1) to save your
setting and exit the Menu Mode.

Chapter 4: Menu Mode
Note: Please print the current Menu Mode settings before you
reset or change them. This is the only way to have a
record of the settings.
In Menu Mode, you use the front panel keys to change the
defaults for the printer parameters. The changes you make in
the Menu Mode are automatically saved when you exit the
Menu Mode and are retained, even when you turn the printer
off.

Menu Mode Keys

GROUP Key

Prints the next Group in the Menu.
With the SHIFT key, prints the previous Group.
ITEM Key

Prints the next Item in the Group.
With the SHIFT key, prints the previous Item in the Group.
SET Key

Prints the next setting for an Item.
With the SHIFT key, prints the previous setting for an Item.
PRINT Key

Prints a copy of all the Menu settings.
With the SHIFT key, prints the current settings for the
Group selected.
MENU Light

Glows when the printer is in the Menu Mode.

Entering and Exiting Menu Mode

Printing the Menu Settings

To enter or exit the Menu Mode, hold SHIFT while pressing
SEL.

Printing the Current Menu Settings

Resetting the Menu to the Factory Defaults
Note: Please print the current Menu Mode settings before you
reset or change them. This is the only way to have a
record of the settings.
To reset the Menu to the standard settings (factory defaults):
1 Turn the printer off.
2 Press SEL + LF while turning the printer on.

26 Microline 420/421User’s Guide

1 Make sure paper is loaded in the printer.
2 Press and hold SHIFT, then press SEL to enter the Menu
Mode.
3 Press PRINT (PARK key).
Printing All Menu Settings

To print out a listing of the settings for all menu items,
regardless of the emulation selected or the accessories installed:
1 Make sure paper is loaded in the printer.
2 Press and hold SHIFT, then press SEL to enter the Menu
Mode.
3 Press and hold SHIFT, then press PRINT QUALITY.

Changing the Menu Settings
Note: Please print the current Menu Mode settings before you
reset or change them. This is the only way to have a
record of the settings.
1 Press and hold SHIFT, then press SEL to enter the Menu
Mode.
2 Use the GROUP, ITEM and SET keys to make your changes:
a Press GROUP until the Group you wish to change appears
in the first column.
b Press ITEM until the Item you wish to change appears in
the second column.
c Press SET until the setting you want appears in the third
column.
3 Press and hold SHIFT, then press SEL to exit the Menu Mode
and save your settings.
Important!
If you turn off the printer without first exiting the Menu
Mode, the changes you have made will be lost.

Mode Menu 27

Menu Settings Table
For a complete explanation of each menu item, see “Explanations of Menu Items” later in this chapter.
The table below shows the items which may appear in the menu. Settings which are engaged at the factory (defaults) are set in bold
italic. Some groups or entries will only appear when a specific emulation is engaged, as noted.
Group

Item

Settings (Defaults are set in bold italic)

Printer Control

Emulation Mode

IBM PPR, Epson FX, ML

Font

Print Mode

LQ Courier, LQ Roman, LQ Swiss, LQ Swiss Bold, LQ Orator, LQ Gothic,
LQ Prestige, Utility, HSD

DRAFT Mode

HSD, SSD

Pitch

10 cpi, 12 cpi, 15 cpi, 17.1 cpi, 20 cpi

Proportional Spacing

No, Yes

Style

Normal, Italics

Size

Single, Double

Character Set

• Set I, Set II [Epson and IBM mode]
• Standard, Line Graphics, Block Graphics [ML Mode]

Language Set

American, French, German, British, Danish I, Swedish, Italian, Spanish I,
Japanese, Norwegian, Danish II, Spanish II, Latin American, French Canadian,
Dutch, Publisher

Zero Character

Slashed, Unslashed

Code Page

USA, Canada French, Multilingual, Portugal, Norway, BRASCII, Abicomp,
Multilingual 858, ISO 8859-15

Symbol Sets

28 Microline 420/421User’s Guide

Menu Settings Table (Continued)
Group

Item

Settings (Defaults are set in bold italic)

Rear Feed

Line Spacing

6 LPI, 8 LPI

Form Tear-Off

Off, 500 ms, 1 sec, 2 sec

Skip Over Perforation

No, Yes

Page Width (wide model)

13.6", 8"

Page Length

11", 11-2/3", 12", 14", 17", 5", 3", 3.5", 4", 5.5", 6", 7", 8", 8.5"

Line Spacing

6 LPI, 8 LPI

Form Tear-Off

Off, 500 ms, 1 sec, 2 sec

Skip Over Perforation

No, Yes

Page Width (wide model)

13.6", 8"

Page Length

11", 11-2/3", 12", 14", 17", 5", 3", 3.25", 3.5", 4", 5.5", 6", 7", 8", 8.5"

Bottom Feed

Mode Menu 29

Menu Settings Table (Continued)
Group

Item

Settings (Defaults are set in bold italic)

Top Feed

Line Spacing

6 LPI, 8 LPI

Form Tear-Off*

Off, 500 ms, 1 sec, 2 sec

Bottom Margin

Valid, Invalid

Page Width (wide model)

8", 13.6"

Page Length

11", 11-2/3", 12", 14", 17", 5", 3", 3.25", 3.5", 4", 5.5", 6", 7", 8", 8.5"

Wait Time

500 ms, 1 sec, 2 sec

Page Length Control

by Actual Page Length, by MENU Setting

Graphics

Bi-directional, Uni-directional

7 or 8 Bit Graphics†

8, 7

Receive Buffer Size

1 Line, 32K, 64K, 128K

Paper Out Override

No, Yes

Set-Up

* Appears only when the optional Roll Paper Stand is installed.
† Appears only when the MICROLINE emulation is selected.

30 Microline 420/421User’s Guide

Menu Settings Table (Continued)
Group

Item

Settings (Defaults are set in bold italic)

Setup (cont..)

Print Registration 1

0, range to 0.25 mmm to the right or left, set in 0.05 mm increments
• press SEL to shift registration to the left;
• press SHIFT + SEL to shift registration to the right.

Print Registration 2

0, range to 0.25 mmm to the right or left, set in 0.05 mm increments
• press SEL to shift registration to the left;
• press SHIFT + SEL to shift registration to the right.

7 or 8 Bits Data Word*

8, 7

Operator Panel Function

Full Operation, Limited Operation

Reset Inhibit

No, Yes

Print Suppress Effective

No, Yes

Auto LF

No, Yes

Auto CR

†

No, Yes

CSF Bin Select**

Bin 1, Bin 2

Print DEL Code*

No, Yes

* Appears only when MICROLINE emulation is selected.
† Appears only when the IBM emulation is selected.
** Appears only if the optional Cut Sheet Feeder is installed.
Mode Menu 31

Menu Settings Table (Continued)
Group

Parallel I/F

Item

Settings (Defaults are set in bold italic)

SI Select Pitch (10 cpi)*

15 cpi, 17.1 cpi

SI Select Pitch (12 cpi)*

12 cpi, 20 cpi

Time Out Print

Valid, Invalid

Auto Select

No, Yes

Centering Position

DEFAULT, MODE 1, MODE 2

CSF Type†

Wide, Narrow

Power Saving

Enable, Disable

Power Save Time

5 min, 10 min, 15 min, 30 min, 60 min

I-Prime

Buffer Print, Buffer Clear, Invalid

Pin 18

+5V, Open

Auto Feed XT**

Invalid, Valid

Bi-Direction

Enable, Disable

* Appears only when the IBM emulation is selected.
†

Appears only when optional Cut Sheet Feeder is installed.

** Appears only if the Epson emulation is selected.

32 Microline 420/421User’s Guide

Menu Settings Table (Continued)
Group

Item

Settings (Defaults are set in bold italic)

Serial IF*

Parity

None, Odd, Even

Serial Data 7/8 Bits

8 Bits, 7 Bits

Protocol

Ready/Busy, X/On / X/Off

Diagnostic Test

No, Yes

Busy Line

SSD-, SSD+, DTR, RTS

Baud Rate

19200 bps, 9600 bps, 4800 bps, 2400 bps, 1200 bps, 600 bps, 300 bps

DSR Signal

Valid, Invalid

DTR Signal

Ready on Power Up, Ready on Select

Busy Time

200 ms, 1 sec.

* Appears only when the optional Serial Interface is installed.

Mode Menu 33

Menu Settings Table (Continued)
Group

Item

Settings (Defaults are set in bold italic)

CSF Bin 1*

Line Spacing

6 LPI, 8 LPI

Bottom Margin

Valid, Invalid

Page Width (Wide model)

8", 13.6"

Page Length

11", 11-2/3", 12", 14", 17", 5", 3.5", 4", 5.5", 6", 7", 8", 8.5"

Line Spacing

6 LPI, 8 LPI

Bottom Margin

Valid, Invalid

Page Length

11", 11-2/3", 12", 14", 17", 5", 3.5", 4", 5.5", 6", 7", 8", 8.5"

CSF Bin 2*

* Appears only when the optional Cut Sheet Feeder is installed.

34 Microline 420/421User’s Guide

Explanations of Menu Items

Auto Feed XT, Default = Invalid

Change this setting to 8 if your system uses 8-bit graphics.

Epson emulation only. In the Epson emulation, the XT signal
on pin 14 of the parallel interface can control automatic line
feed. Some interface cables are wired in such a way that
automatic line feed is always in effect: this item eliminates this
potential problem. If your system uses pin 14 of the parallel
interface to control automatic line feed, change the setting to
Valid.

7 or 8 Bit Data Word, Default = 8

Auto Select, Default = No

These explanations are in alphabetical sequence to make it
easier to look them up. Some items only appear when optional
accessories are installed; others appear in several groups in the
menu.
7 or 8 Bit Graphics, Default = 7

Change this setting to 7 if your system uses 7-bit data word
lengths.
Auto CR, Default =No

IBM emulation only. If you want the printer to automatically
add a carriage return when a Line Feed is received at the end of
a line, change the setting to Yes.

Determines whether or not your printer will automatically be
selected after you load in paper. With the factory default
engaged, the printer will be deselected so that you can set the
Top of Form. If you always use the same Top of Form position,
change the setting to Yes.
Baud Rate, Default = 9600 bps

Auto LF, Default = No

Appears only if optional Serial Interface is installed. Set this to
match your system’s transmission speed.

If your printout is consistently double spaced, select No; if it
overprints, select Yes.

Bi-direction, Default = Enable

Change this setting if you wish to disable bidirectional
transmission (PnP) in Nibble mode.

Mode Menu 35

Bottom Margin, Default = Valid

Centering Position, Default = DEFAULT

Change to Invalid if you want the printer to ignore the bottom
margin setting.

Used to limit printhead travel when printing narrow columns.

CAUTION!!
Setting the Bottom Margin to Invalid can cause loss of data
and damage the printhead by allowing printing without paper.
Busy Line, Default = SSD-

Appears only when the optional Serial Interface is installed. If
Ready/Busy protocol (factory default) is selected, you can
choose which line your system monitors for a busy signal:
•
•
•
•

SSD -9V, select SSDSSD +9V, select SSD+
DTR -9V, select DTR
RTS -9V, select RTS

• Select Mode 1 for the narrow carriage printer.
• Select Mode 1 or Mode 2 for the wide carriage printer.
Character Set, Default = IBM Set I

Epson and IBM emulations only. Use this to switch character
sets to IBM Set II
Character Set, Default = Standard

MICROLINE emulation only. Use this to switch the character
set to Line Graphics.
Code Page, Default = USA

Choose the Code Page character set you wish to use: USA,
Canada French, Multilingual, Portugal, Norway, BRASCII,
Abicomp, Multilingual 858, or ISO 8859-15.

Busy Time, Default = 200 ms

CSF Bin Select, Default = Bin 1

Appears only when the optional Serial Interface is installed.
Sets the length of the busy signal when the Ready/Busy
protocol (factory default) is engaged,

Appears only when the optional Dual-Bin Cut Sheet Feeder is
installed. Use this to switch to Bin 2 as the default.

36 Microline 420/421User’s Guide

CSF Type, Default = Wide

Emulation Mode, Default = IBM PPR

To avoid paper jams, change this setting to Narrow if you are
using the optional Cut Sheet Feeder on the wide model ML421
printer.

Selects the printer command set (emulation) you want to
engage.

Diagnostic Test, Default = No

Sets the character pitch used when the ESC SI command is
received.

Appears only when the optional Serial Interface is installed.
Select yes to perform a diagnostic test of the serial interface.
DRAFT Mode, Default = HSD

Applies only when the Print Mode is set to DRAFT. Selects the
draft mode to be used: HSD (High Speed Draft) or SSD (Super
Speed Draft).

ESC SI Pitch, Default = 17 cpi

Form Tear-Off, Default = Off

Choose 500 ms, 1 sec, or 2 sec to turn the Form Tear-Off
feature on and to set the time interval for the printer to wait
before advancing the paper.
Graphics, Default = Bi-directional

DSR Signal, Default = Valid

Appears only when the optional Serial Interface is installed.
Used with the Ready/Busy protocol (factory default) to select
the way your system handles the DSR signal.

Change to uni-directional graphics for better registration, but
slower printing. With this set for bi-directional, you can
optimize the registration using the Print Registration setting in
the Menu.

DTR Signal, Default = Ready on Power Up

Appears only when the optional Serial Interface is installed.
Change to Ready on Select if the DTR signal is required when
the printer is selected (leave as Ready on Power Up if the DTR
signal is required when the printer is turned on).

Mode Menu 37

I-Prime, Default = Buffer Print

Determines what the printer will do when it receives the
I-Prime signal from the software.
• Buffer Print: prints out the buffer contents before resetting.
• Buffer Clear: dumps the buffer contents immediately.
• Invalid: causes the printer to ignore the I-Prime command.
Select this setting if you wish to enter settings through the
printer’s control panel which will not be automatically
overridden by the software’s settings when the I-Prime
signal is sent.
Language Set, Default = American

Replaces certain standard symbols with special characters used
in foreign languages.
Line Spacing, Default = 6 lpi

Change to 8 lines per inch (lpi) to get more lines on a page.

Operator Panel Function, Default = Full Operation
Change to Limited Operation to deactivate the PRINT QUALITY
and CHARACTER PITCH buttons, so that these features can

only be controlled through your software. This prevents these
from being changed from the control panel when several
people are using the printer.
Important!
This feature also prevents access to the Menu. To access the
Menu in these circumstances, turn the printer off, then hold
down the SEL key while turning on the printer.
Page Length, Default = 11"

Selects the length of the paper you are using. This enables the
printer to keep track of the initial printing position (TOF) on
each page.
Page Length Control, Default = by Actual Page Length

If you are printing single sheets no longer than 17 inches and
wish the printer to acknowledge the menu setting for Top Feed
Page Length, change the setting to “by Menu Setting.”

38 Microline 420/421User’s Guide

Page Width, Default = Depends on Feed Path

Parity, Default = None

Wide carriage model only.

Appears only when the optional Serial Interface is installed.
Selects the type of parity your system uses: None, Odd or
Even.

For rear and bottom paths, the default is 13.6". Change to 8" if
you will be printing on narrow paper. This prevents printing on
the platen which can damage the printhead and the platen, and
can cause loss of data.
For the top feed path the default is 8". Change to 13.6" to print
on wide paper.

Pin 18, Default = +5V

Sets the signal on pin 18 to +5 volts or open.
Pitch, Default = 10 cpi

Choose the character width, in characters per inch (cpi).
Paper Out Override, Default = No

Senses when less than 1" (25 mm) of paper remains and stops
printing. Change to Yes to override the sensor and print closer
to the bottom of the page.
Caution!!
Engaging Paper Out Override can cause loss of data and
damage the printhead by allowing printing without paper.

Power Save Time, Default = 5 min

Sets the interval the printer waits for more data before it goes
into the power save mode. Power Saving must be set to Enable
(the factory default) for this to be effective.
Power Saving, Default = Enable

Change to Disable if you wish to prevent the printer from
entering the Power Save mode after the selected interval.

Mode Menu 39

Print Mode, Default = Utility

Receive Buffer Size, Default = 64K

Choose the quality and typeface of printing. Switch to NLQ
Courier or NLQ Gothic for Near Letter Quality printing. If you
are printing draft-type documents, select DRAFT, then select
either HSD or SSD under DRAFT Mode. Both of these Items
are in the Font Group.

Selects the amount of memory devoted to holding received
data. Choosing 1 Line will tie up your computer while printing,
but if you abort the print job, the printer will stop much sooner.

Print Registration, Default = 0

Change the setting as required to obtain the best registration for
bi-directional printing.
Print Suppress Effective, Default = Yes

If your system uses the DC1 and DC3 codes for something
other than the print suppress mode, change the setting to No.
Proportional Spacing, Default = No

Change the setting to Yes to engage proportional spacing of
characters.
Protocol, Default = Ready/Busy

Appears only if the optional Serial Interface is installed.
Change to X-ON / X-Off if that is the type of protocol your
system uses.

40 Microline 420/421User’s Guide

Reset Inhibit, Default = No

Select Yes if you wish the printer to ignore the reset command
sent by software. This prevents your software from changing
the settings you make through the front panel controls or
through printer commands.
Note: This will also prevent your software from clearing out
existing settings when you finish printing one document
and switch to another.
Serial Data 7/8 Bits, Default = 8 Bits

Appears only if the optional Serial Interface is installed.
Change to 7 Bits if you systems uses a 7-bit data format.
SI Select Pitch 10 cpi, Default = 17.1 cpi

IBM emulation only. Sets the pitch to be engaged when the
printer control panel is set for 10 cpi and the SI command is
received.

SI Select Pitch 12 cpi, Default = 20 cpi

Wait Time, Default = 1 sec

IBM emulation only. Sets the pitch to be engaged when the
printer control panel is set for 12 cpi and the SI command is
received.

Sets the amount of time the printer will wait for more data
before moving to the form tear-off position.
Zero Character, Default = Slashed

Size, Default = Single

Change to Double for double width and height printing.

If you do not want the printer to use a slash to distinguish the
number zero from the capital letter O, change the setting to
Unslashed.

Skip Over Perforation, Default = No

Change to Yes if you want the printer to go to the next page
when it comes within 1" (25 mm) of the bottom of the page.
Keep it set to No if your software has its own page formatting
controls.
Style, Default = Normal

Change to italics if you want the printed characters to be
slanted.
Time Out Print, Default = Valid

If your software spends a long time processing between
portions of data it feeds to the printer, change the setting to
Invalid to keep your printer from dumping the received data
while it is waiting for more.

Mode Menu 41

Chapter 5: Maintenance
Replacing the Ribbon Cartridge
Important!
Make sure you have the correct replacement ribbon for the
your printer. The wrong ribbon will not print when installed
in your printer. Look for the printer model number on the
ribbon package.
Ribbon Cartridge Handling

1 Make sure the printer is turned OFF.
2 Open the access cover and center the printhead.

CAUTION!
The printhead may be HOT!

5 Turn the take-up knob (1) in the direction of the arrow to
take up any ribbon slack.

3 Swing the used ribbon cartridge up off the printhead, lift it
out, and discard it.

6 Close the access cover and turn the printer back on.
CAUTION!
If ribbon should contact the eyes:

4 Unpack the new ribbon cartridge and install it.
Important!
Do not remove the ribbon shield (1) from the ribbon!

Flush eyes with large quantities of water for 15 minutes,
keeping eyelids open with fingers. Seek medical attention.
If ribbon should contact the skin

Wash thoroughly with soap and water.
For more information

See the Material Safety Data Sheet in your Warranty,
Regulatory, and Safety Information booklet.

Maintenance 43

Loading Paper

Loading Rear Feed Paper from the Back of the Printer

Rear Feed

Note: These instructions assume you have ready access to the
back of the printer. If you do not, skip down to “Loading
Rear Feed Paper from the Front of the Printer.”

Note: If you have any paper in the paper path, remove it
before installing rear feed paper.
Lock Lever

1 Make sure the paper lever is forward (position marked
“REAR”).

Upper Tractor Cover
Pins

2 Open the access cover (1).

44 Microline 420/421 User’s Guide

3 Grasp the sheet guide. Lift it slightly, then slide it back.

4 Pivot the sheet guide forward and gently rest it against the
roller assembly.
Careful!
If you push the sheet guide too hard against the roller
assembly, it may dislodge it. If it does, be sure to reseat the
roller assembly before continuing.

Maintenance 45

5 From the back of the printer, locate the tractors (1).

6 Open the lock levers (1) and move the right tractor (as
viewed from the back of the printer) to the reference mark
(2) matching the width of the paper you are loading. Then
close the lock lever on the right tractor:

ML421
ML420

Note: The movement of the right tractor is limited to ensure
that the paper covers the paper sensor.
7 Open the tractor covers.

46 Microline 420/421 User’s Guide

8 Place continuous forms paper on the first two pins of either
tractor.
Important!
You must keep the number of paper holes engaged on either
pin the same. If you don’t the paper will skew and jam.

10 Adjust the left tractor until the holes in the paper are
centered on the pins then lock the lever and close the left
tractor cover.
Note: If the paper is too loose or too tight it can cause jams.

9 Close the right tractor cover.

Maintenance 47

11 Lower the sheet guide and slide it toward the front of the
printer until the marks align.

12 Place the wire guide (“1” in the illustration for the step
above) in the sheet guide on the pull-up roller assembly.

13 Press FF/LOAD.
Note: The factory default setting for the Top of Form (where
the printing should begin) is 1" down from the top of the
page. To change the setting, see “Top of Form (TOF)”
in Chapter 3.

48 Microline 420/421 User’s Guide

Loading Rear Feed Paper from the Front of the Printer

2 Open the access cover (1).

Note: These instructions assume you do not have ready access
to the back of the printer. If you do, go back to “Loading
Rear Feed Paper from the Rear of the Printer” earlier
in this chapter.
Lock Lever
Upper Tractor Cover
Pins
3 Grasp the tabs and lift off the sheet guide.

1 Make sure the paper lever is forward (position marked
“REAR”).

4 Pull up on the lock levers to release them.

Maintenance 49

Note: The movement of the left tractor (as viewed from the
front of the printer) is restricted to ensure that the
paper covers the paper out sensor.

7 Open the tractor covers and place continuous forms paper on
the first two pins of either tractor, then close the left tractor
cover.

5 You will find reference marks (1 in illustration below) on the
printer for the two most common paper sizes:

Important!
You must keep the number of paper holes engaged on either
pin the same. If you don’t the paper will skew and jam.

ML420:

ML421:

6 Move the left tractor to the position to match your paper size
and push back on the lever to lock it in place, then move the
right tractor to fit the width of the paper.

50 Microline 420/421 User’s Guide

8 Adjust the position of the right tractor to center the holes in
the paper on the pins. Then, close its tractor cover and push
back the lock lever. Do not stretch the paper.

9 Reinstall the sheet guide.

Note: If the paper is too loose or too tight it can cause jams.

Maintenance 51

10 Place the wire guide (1) in the sheet guide on the pull-up
roller assembly.

52 Microline 420/421 User’s Guide

11 Press FF/LOAD.
Note: The factory default setting for the Top of Form (where
the printing should begin) is 1" down from the top of the
page. To change the setting, see “Top of Form (TOF)”
in Chapter 3.

Top Feed (Single Sheets)
Note: If you have continuous form paper in the path, press
PARK to remove it before loading single sheets.

3 Open the acoustic cover (1) and raise the sheet guide to the
single-sheet position. Pivot the wire feed guide (2) up into
the sheet guide.

1 Make sure the printer is on and deselected (SEL light off).
2 Place the paper lever in the center position (marked “TOP”).

Maintenance 53

4 Adjust the paper feed guides (1) for the width of the paper,
then place a sheet of paper in the separator. The paper will
feed into the printer.

Important!
If the paper does not feed in, remove it. Check the paper lever
position. Make sure the ALARM light is on: if it is flashing,
hold the SHIFT key and press the CHARACTER PITCH/RESET
key. Reload the sheet of paper.
Note: The factory default setting for the Top of Form (where
the printing should begin) is 1" down from the top of the
page. To change the setting, see “Top of Form (TOF)”
in Chapter 3.

54 Microline 420/421 User’s Guide

Clearing Paper Jams

5 Lift the sheet guide (1) and reload paper. Make sure you
lock the tractor covers.

Rear-Feed Paper Jams
1 Turn off the printer.
2 Use the platen knob to back the paper all the way out of the
printer.
CAUTION!
Make sure the printer is turned off before you open the access
cover.
3 Open the access cover (1) and remove the pull-up roller
assembly (2). Remove any torn pieces of paper.

5 Lower the sheet guide, then install the pull-up roller
assembly and close the access cover.

6 Turn on the printer and press FF/LOAD.

Maintenance 55

Rear-Feed, Repeating Paper Jams

Bits of Paper Stuck in the Paper Path

If the paper keeps jamming, you may have:

1 Turn off the printer.
2 Use the platen knob to back the paper all the way out of the
printer.

• defective paper
• misaligned paper
• bits of paper stuck in the paper path
Defective Paper

Replace the paper with a fresh stack.
Misaligned Paper

1 Turn off the printer.
2 Use the platen knob to back the paper all the way out of the
printer.
3 Tear off a couple of sheets of paper, leaving a new, clean,
square-cut edge.
4 Reload the paper and turn the printer back on.

56 Microline 420/421 User’s Guide

CAUTION!
Make sure the printer is turned off before you open the access
cover.
3 Open the access cover (1) and remove the pull up roller
assembly (2). Then grasp the tabs (3) on the sheet guide (4)
and lift it off the printer.

4 Remove any torn pieces of paper.
5 Fold some continuous-form paper over three times to make a
page four sheets thick. Then, load it on the tractors and close
and lock the covers.

8 Load regular paper, close and lock the tractor covers.

9 Install the sheet guide, then install the pull-up roller
assembly and close the access cover.

6 Use the platen knob to draw the quadruple-thick page
around the platen. This brings out jammed pieces of paper.
7 Remove the paper pieces. Then, use the platen knob to back
the paper out.

10 Turn the printer on and press FF/LOAD.

Maintenance 57

Single-Sheet Paper Jams
1 Turn off the printer.
2 Use the platen knob to back the paper out.

3 Open the access cover (1) and remove the pull-up roller
assembly (2).

4 Remove any torn pieces from around the carriage.
5 Reinstall the pull-up roller assembly and close the access
cover.

58 Microline 420/421 User’s Guide

Cleaning the Housing
You should clean the printer housing every six months (or after
about 300 hours of operation).

4 Use a clean, dry cloth to dust around the carriage shaft and
platen. Remove any loose bits of paper.
5 Reinstall the pull-up roller assembly and close the access
cover.

CAUTION!
Never use strong solvents or strong detergents on the
cabinet—they could damage the housing.
1 Turn off the printer.
2 Use the platen knob to back the paper out of the printer.
CAUTION!
Make sure the printer is turned off before you open the access
cover.
3 Open the access cover (1) and remove the pull-up roller
assembly (2).

Maintenance 59

Chapter 6: Troubleshooting
General Information
Here are some general things to check before proceeding with
detailed troubleshooting.
• Is the printer plugged in and turned on?
• Are the connections (power and interface) secure?
• Is the product being operated under the proper ambient
conditions?
• Does the paper being used meet the specifications for this
product?
• Is the paper properly installed?
• Is the ribbon properly installed?
• Is an Oki ribbon being used?
• Is the printhead gap correctly set?
• Are the correct printer drivers being used for the printer?

Note: Settings in your software application will normally
override any settings in your printer driver.
Printer driver settings normally override settings from
the printer menu or printer front panel.

Problems / Solutions
Problem

The I-Prime signal will automatically override any front panel
settings you have made. To eliminate this problem, enter the
Menu Mode, go to the Parallel Interface group and change the
setting for I Prime to Invalid.

My word processor files do not print the way I have the menu
and front panel set.

For more information on changing menu settings, see
“Changing the Menu Settings” in Chapter 4.

Solution
Remember:

Problem

• Settings in your software application can override settings in
your printer driver.
• Your printer driver settings can override any settings from the
printer menu or printer front panel.
Before sending a file to the printer, many word processors send
either an “initialization string” or an I-Prime signal to the
printer.

Nothing happens when I turn on the printer.
Solution
Check the power cord connection to the outlet and to the
printer. If you are using a power strip, make sure it is turned on,
and that the fuse hasn’t blown or that the circuit breaker hasn’t
tripped.

The initialization string contains codes that override the panel
and menu settings. To change your printer to ignore the reset
code, enter the Menu Mode, go to the Set-Up group and change
the setting for Reset Inhibit to Yes.

Troubleshooting 61

Problem

The printer does not print when the computer sends data.

I'm getting strange symbols, incorrect fonts, etc., when I try to
print a document.

Solutions
1 Is the SEL light on? If not, press the SEL key.
2 Check that the interface cable is securely connected to both
the printer and the computer.
3 If you have the optional serial interface board installed,
check to be sure that it is firmly seated in the printer.

62 Microline 420/421 User’s Guide

Solutions
1 Check to be sure that the printer driver you have selected in
your software matches the printer emulation.
• Press SHIFT and SEL keys, then press GROUP key.
• This will print a line showing the emulation you have
selected.
2 If you have embedded any printer commands in your
software, check to be sure that you entered them correctly.

Problem

Ink smears on the paper when I print narrow columns.

I've installed a new ribbon and the printing is smeared and
streaked.

Solution
This may be caused by excessive printhead travel from the
centering position. Enter the Menu and set the Centering
Position to MODE 1. See “Using Your Printer, Menu Mode.”

Solution
The ribbon shield (1) is either loose or missing.

For the wide-carriage printer, if MODE 1 doesn't work, try
setting the Centering Position to MODE 2.

Remove the ribbon cartridge and check the ribbon shield.
• If it is loose, secure it.
• If it is missing, find it and install it.

Troubleshooting 63

Problem

There are dots missing in my printouts.

The ALARM light is on and the Character Pitch 10 light is
flashing.

Solution
The head gap may not be set correctly. Try moving the headgap
lever to a lower setting. If that doesn’t help, the printhead may
be damaged; call for service.

Solution
This indicates that the paper lever is set at the wrong position
for the paper you are trying to use. Move it to the proper
setting.

Problem
The ALARM light is flashing.
Solution
Try turning the printer off and then back on again. If the light
still blinks, call for service.

64 Microline 420/421 User’s Guide

Problem
The ALARM light is on and the Character Pitch 15 light is
flashing.
Solution
This indicates a paper jam. Press the SEL key and correct the
paper jam situation. See “Clearing Paper Jams,” in Chapter 4.

Problem

The printer needs paper. The ALARM is not on and I can’t load
paper.

The Print Quality and Character Pitch keys on the front panel
don't work.

Solution
1 Press and release the SEL key.
2 Press and hold the SHIFT key and press the RESET /
CHARACTER PITCH key.
The ALARM light comes on and you can now load paper.

Solution
The Operator Panel Function in the printer menu can be used to
disable these buttons (Limited Function). If the printer is part of
a customized system or if it is used by a number of people, the
system manager may have used this option to make sure the
printer is always set properly.

Problem

Check with your system manager before changing any menu
settings.

Continuous-form paper sticks to the sheet guide.
Solution
In cold dry weather, static charges can build up and make the
paper cling to the sheet guide. Try moving the paper guides
together so that the paper rests on the guides rather than on the
separator.

Troubleshooting 65

Appendix A: Parts & Accessories
Purchasing Parts & Accessories
Before you purchase, know your printer model number (see the
front of the unit) and have the correct part number and
description of the item. Item descriptions and part numbers are
provided in this section.
• Consult the dealer where your purchased your printer.
• Locate an Authorized Oki Data Reseller by visiting one of
our web sites
http://my.okidata.com (allows you to register your
product and personalize your own support needs)
http://www.okidata.com (provides general information)

• In the United States, purchase directly from Oki Data
- Via the Internet
http://my.okidata.com
http://www.okidata.com

- Via telephone
Order toll-free by phone at 1-800-654-3282
(1-800-OKI-DATA) using VISA®, MasterCard®, or
AmEx®.
• In Canada, call 888-309-4570.

Replacement Parts

Item

Part Number

Both Models
Ribbon Cartridge ( ) ------------------------------- 42377801
Platen Knob ( ) ------------------------------------- 51902220
Power Cord ( ) ------------------------------------- 56631801
Printhead ( ) ---------------------------------------- 41923901
Model ML420
Access Cover ( ) ----------------------------------- 42115401
Sheet Guide ( ) ------------------------------------- 51009509
Pull-Up Roller Assembly ( ) --------------------- 42044701
Model ML421
Access Cover ( ) ----------------------------------- 42115301
Sheet Guide ( ) ------------------------------------- 51009410
Pull-Up Roller Assembly ( ) --------------------- 42045701

Accessories 67

Accessories
Option

Part Number

Model ML420
Pull Tractor, Top-Mount ( ) ---------------------- 70030501
Push Tractor, Bottom-Mount ( ) ---------------- 70030701
Roll Paper Stand ( ) ------------------------------- 70023301
Model ML421
Pull Tractor, Top-Mount ( ) ---------------------- 70030601
Push Tractor, Bottom-Mount ( ) ---------------- 70030801
Both Models
Cut Sheet Feeder ( ) ------------------------------- 70030101
Serial Interface ( ) --------------------------------- 70012801
OkiLAN® 6120i 10/100 Base-T Ethernet
Internal Print Server (not shown) --------------- 70046501
OkiLAN 6020e 10/100 Base-T Ethernet
External Print Server (not shown) --------------- 70036001
OkiLAN 6010 10 Base-T Ethernet
External Print Server (not shown) --------------- 70034401

68 Microline 420/421 User’s Guide

Appendix B: Printer Control Codes
This section lists the most commonly used printer control
codes.
You will find a comprehensive listing of the control codes
(English only), on your Printer CD.
To access it:
1 Place the CD in your CD-ROM drive and wait for it to
AutoPlay.
2 Select your printer model, then click Continue.
3 Click Documentation and follow the on-screen prompts to
view the file.

IBM Proprinter III Commands
IBM Command

ASCII

Decimal

Backspace

Carriage Return

Character Pitch
Select 10 cpi
Select 12 cpi
Select 15 cpi
Select Condensed Print

DC2
ESC :
ESC g
ESC SI, or SI

18
27 58
27 103
27 15, or 15

Character Sets
IBM Set I
IBM Set II
Publisher
Slashed Zero
Unslashed Zero

ESC 7
ESC 6
ESC ! Z
ESC ! @
ESC ! A

27 55
27 54
27 33 90
27 33 64
27 33 65
69

IBM Proprinter III Commands
(continued)
IBM Command

ASCII

Decimal

Double Width On
Double Width Off

ESC W 1
ESC W 0

27 87 49
27 87 48

Emphasized Printing On
Emphasized Printing Off

ESC E
ESC F

27 69
27 70

Enhanced Printing On
Enhanced Printing Off

ESC G
ESC H

27 71
27 72

Form Feed

Form Length
n inches (n = 1 to 255)
n lines (n = 1 to 255)

ESC C NUL n 27 67 0 n
ESC C n
27 67 n

Horizontal Tab, Execute

Italics On
Italics Off

ESC % G
ESC % H

27 37 71
27 37 72

70 Microline 420/421 User’s Guide

IBM Command

ASCII

Decimal

Line Feed, Execute
w/ Carriage Return
n/144" (n = 1 to 127)
n/216" (n = 0 to 255)
Reverse
Auto Line Feed On
Auto Line Feed Off

LF
ESC % 5 n
ESC J n
ESC ]
ESC 5 1
ESC 5 0

10
27 37 53 n
27 74 n
27 93
27 53 49
27 53 48

ESC 0
ESC 1

27 48
27 49

ESC A n

27 65 n

ESC 2

27 50

ESC % 9 n

27 37 57 n

ESC 3 n

27 51 n

Line Spacing
Set Spacing to 1/8"
Set Spacing to 7/72"
Set Spacing to n/72"
(n = 0 to 255)
Store Spacing Set
by ESC A n
Set Spacing to n/144"
(n = 1 to 127)
Set Spacing to n/216"
(n = 0 to 255)

IBM Proprinter III Commands
(continued)

IBM Command

ASCII

Decimal

Software I-Prime

ESC } NUL

27 125 0

Stop Printing

ESC j

27 106

IBM Command

ASCII

Decimal

Overscore On
Overscore Off

ESC _ 1
ESC _ 0

27 95 49
27 95 48

Subscript On
Superscript On
Subscript/Superscript Off

ESC S 1
ESC S 0
ESC T

27 83 49
27 83 48
27 84

Paper Out Sensor Off
Paper Out Sensor On

ESC 8
ESC 9

27 56
27 57

Top of Form,
Set at Current Position

ESC 4

27 52

Print Quality, Select HSD

ESC # 0

27 35 48

Print Suppress Mode On
ML420
ML421
Print Suppress Mode Off

Underline Printing On
Underline Printing Off

ESC - 1
ESC - 0

27 45 49
27 45 48

ESC Q ETX
ESC Q SYN
DC1

27 81 3
27 81 22
17

Uni-Directional Print On
Uni-Directional Print Off

ESC U 1
ESC U 0

27 85 49
27 85 48

Vertical Tab, Execute

Proportional Spacing On
Proportional Spacing Off

ESC P 1
ESC P 0

27 80 49
27 80 48

Reset: Clear Print Buffer

CAN

Control Codes 71

Epson FX Commands
Epson Command

ASCII

Decimal

Backspace

Carriage Return,
Execute

Character Pitch
Select 10 cpi
Select 12 cpi
Select 15 cpi
Begin 10 cpi

ESC P
ESC M
ESC g
ESC SI, or SI

27 80
27 77
27 103
27 15, or 15

Cancel Condensed Print

DC2

Delete

DEL

127

72 Microline 420/421 User’s Guide

Epson Command

ASCII

Decimal

Double Height On
Double Height Off

ESC w 1
ESC w 0

27 119 49
27 119 48

Double Width On
Double Width Off

ESC W 1
ESC W 0

27 87 49
27 87 48

Emphasized Print On
Emphasized Print Off

ESC E
ESC F

27 69
27 70

Enhanced Print On
Enhanced Print Off

ESC G
ESC H

27 71
27 72

Epson Set 1, Select
Epson Set 2, Select

ESC t 0
ESC t 1

27 116 48
27 116 49

Italic Printing On
Italic Printing Off

ESC 4
ESC 5

27 52
27 53

Form Feed

Epson FX Commands (continued)
Epson Command

ASCII

Form Length
n Inches (n = 1 to 22)
n Lines (n = 1 to 127)

ESC C NUL n 27 67 0 n
ESC C n
27 67 n

Horizontal Tab

Justification
Left
Center
Right
Full

ESC a 0
ESC a 1
ESC a 2
ESC a 3

27 97 48
27 97 49
27 97 50
27 97 51

ESC P
ESC M
LF
ESC J n
ESC % 5 n

27 80
27 77
10
27 74 n
27 37 53 n

ESC j n

27 106 n

Line Feed, Execute
Select 10 cpi
Select 12 cpi
w/ Carriage Return
n/216" (n = 0 to 255)
n/144" (n = 0 to 127)
Reverse, n/216"
(n = 0 to 255)

Decimal

Epson Command

ASCII

Decimal

Line Spacing, Set
n/144" (n = 0 to 127)
n/216" (n = 0 to 255)
n/72"
(n = 0-85 or 128-213)
1/6"
1/8"
7/72"

ESC % 9 n
ESC 3 n
ESC A n

27 37 57 n
27 51 n
27 65 n

ESC 2
ESC 0
ESC 1

27 50
27 48
27 49 n

Paper Out Sensor Off
Paper Out Sensor On

ESC 8
ESC 9

27 56
27 57

Control Codes 73

Epson FX Commands (continued)
Epson Command

Print Quality/Font
Select HSD/SSD
(depends on setting
for Draft Mode)
Select NLQ
Select Courier
(NLQ only)
Select Gothic
(NLQ only)
Select UTL

ASCII

Decimal

Epson Command

ASCII

Decimal

Reset Printer
Clear Buffer & Initialize ESC @
Clear Print Buffer
CAN

27 64
24

Skip Over Perforation,
Cancel

ESC O

27 79

ESC ( 0
ESC x 1

27 40 48
27 120 49

Software I-Prime

ESC } NUL

27 125 0

ESC k 0

27 107 48

Subscript On
Superscript On
Subscript/Superscript Off

ESC S 1
ESC S 0
ESC T

27 83 49
27 83 48
27 84

ESC k 1
ESC x 0

27 107 49
27 120 48

Underline On
Underline Off

ESC - 1
ESC - 0

27 45 49
27 45 48

Print Speed
Half-Speed On
Half-Speed Off

ESC s 1
ESC s 0

27 115 49
27 115 48

Print Suppress Mode On
Print Suppress Mode Off

DC3
DC1

19
17

Uni-Directional Printing
One Line Only
On
Off

ESC <
ESC U 1
ESC U 0

27 60
27 85 49
27 85 48

Vertical Tab, Execute

Proportional Spacing On
Proportional Spacing Off

ESC p 1
ESC p 0

27 112 49
27 112 48

74 Microline 420/421 User’s Guide

Oki MICROLINE Standard
Commands

Oki Command

ASCII

Decimal

Slashed Zero
Unslashed Zero

ESC ! @
ESC ! A

27 33 64
27 33 65

ESC US 1
ESC US 0

27 31 49
27 31 48

Oki Command

ASCII

Decimal

Backspace

Double Height On
Double Height Off

Carriage Return

Double Width Printing

Emphasized Printing On
Emphasized Printing Off

ESC T
ESC I

27 84
27 73

Enhanced Printing On
Enhanced Printing Off

ESC H
ESC I

27 72
27 73

Form Feed

Horizontal Tab, Execute

Italic On
Italic Off

ESC ! /
ESC ! *

27 33 47
27 33 42

Character Pitch
Select 10 cpi
Select 12 cpi
Select 15 cpi
Select 17.1 cpi
Select 20 cpi
Character Sets
Standard
Block Graphic
Line Graphics
Publisher

RS
FS
ESC g
GS
ESC # 3
ESC ! 0
ESC ! 1
ESC ! 2
ESC ! Z

30
28
27 103
29
27 35 51
27 33 48
27 33 49
27 33 50
27 33 90

Control Codes 75

Oki MICROLINE Standard
Commands (continued)

Oki Command

ASCII

Decimal

Paper Out Sensor Off
Paper Out Sensor On

ESC E 1
ESC E 0

27 69 49
27 69 48

Print Quality
Select HSD/SSD
Select NLQ Courier
Select NLQ Gothic
Select Utility

ESC # 0
ESC 1
ESC 3
ESC 0

27 35 48
27 49
27 51
27 48

Print Speed, Set to Full
Print Speed, Set to Half

ESC >
ESC <

27 62
27 60

Oki Command

ASCII

Decimal

Line Feed Commands
w/ Carriage Return
w/o Carriage Return
n/144" (n = 0 to 127)
Reverse

LF
ESC DC2
ESC % 5 n
ESC LF

10
27 18
27 37 53 n
27 10

ESC 6
ESC 8

27 54
27 56

Print Suppress On
Print Suppress Off

DC3
DC1

19
17

ESC % 9 n

27 37 57 n

Proportional Printing
On
Off

ESC Y
ESC Z

27 89
27 90

Reset: Clear Print Buffer

CAN

Line Spacing
Set Spacing to 1/6"
Set Spacing to 1/8"
Set Spacing, in n/144"
(n = 0 to 127)
Skip Over Perforation
1/3" increments
(n = 1 to 9)
Default

ESC G n n
ESC % S 0

76 Microline 420/421 User’s Guide

27 71 n n
27 37 83 48

Oki MICROLINE Standard
Commands (continued)
Oki Command

ASCII

Decimal

Shift-In
Shift-Out

SI
SO

15
14

Software I-Prime

ESC } NUL

27 125 0

Subscript Printing On
Subscript Printing Off
Superscript Printing On
Superscript Printing Off

ESC L
ESC M
ESC J
ESC K

27 76
27 77
27 74
27 75

Underline Printing On
Underline Printing Off

ESC C
ESC D

27 67
27 68

Uni-Directional Print On
Uni-Directional Print Off

ESC ESC =

27 45
27 61

Vertical Tab, Execute

Control Codes 77

Appendix C: Specifications
Note: Specifications are subject to change without notice.

Print Method
Impact dot matrix

Printhead
9 pins, 0.30 mm (0.0118") diameter, with thermal
protection

Interfaces
Standard: Centronics parallel, IEEE-1284 compliant
USB 1.1
Optional: RS-232C Serial
Ethernet Print Servers:
6120i 10/100 Base-T, Internal
6020e 10/100 Base-T, External
6010e 10 Base-T, External

Receive Buffer Size
Maximum 128K

Reliability
Ribbon Life

4 million characters, on average, 10 cpi utility
Printhead Life

400 million characters average in 10 cpi utility mode at
25% duty and 35% page density
Mean Time Between Failures (MTBF)

20,000 hours at 25% duty cycle and 35% page density
Mean Time to Repair (MTTR)

15 minutes

Emulations (co-resident)
• IBM Proprinter III
• Epson FX
• Oki MICROLINE Standard

Print Speed
Mode

Speed
(Characters per Second)

Super Speed Draft (SSD)

570 cps

High Speed Draft (HSD)

507 cps

Utility

380 cps

Near Letter Quality (NLQ)

95 cps

Characters per Line (cpl)
Setting

ML420

ML421

10 cpi

80 cpl

136 cpl

12 cpi

96 cpl

163 cpl

15 cpi

120 cpl

204 cpl

17.1 cpi

137 cpl

233 cpl

20 cpi

160 cpl

272 cpl

Specifications 79

Graphics Resolution

Bar Codes

Emulation

Density

Max. Resolution
(Dots per inch)

IBM, Epson

Single
Double
Quadruple

60 x 216 dpi
120 x 216 dpi
240 x 216 dpi

Oki MICROLINE

Single
Double
Quadruple

72 x 72 dpi
144 x 144 dpi
288 x 144 dpi

•
•
•
•
•
•

Code 39
UPC A, UPC E
EAN 8, EAN 13
Interleaved 2 of 5
Code 128
Postnet

Paper Thickness: Tractor Feed
Rear Feed: 0.014" (0.36 mm) maximum
Bottom Feed: 0.017" (0.44 mm) max.
Requires optional push or pull tractor.

Resident Fonts
Print Quality

Available Fonts

Near Letter Quality

Courier, Gothic

Utility

Gothic

High Speed Draft

Gothic

Super Speed Draft

Gothic

80 Microline 420/421 User’s Guide

Paper Specifications: ML420
Single (Cut) Sheets

Feed: Top Only
Weight: 14 to 24 lb. US Bond (52.6 to 90 g/m2)
Width Range: 7.2" to 8.5" (183 to 216 mm)
Single-part, continuous forms

Feed: Rear, Bottom*
Weight: 12 to 24 lb. US Bond (45 to 90 g/m2)
Width Range: 3" to 10" (76 to 254 mm)
Carbonless continuous forms (orig. + 4 copies)

Feed: Rear, Bottom*
Weight: 9 to 11 lb.
Width Range: 3" to 10" (76 to 254 mm)
Interleaf continuous forms (orig. + 4 copies)

Feed: Rear, Bottom*
Weight: 10 to 12 lb. paper, 9 lb carbon
Width Range: 3 to 10" (76 to 254 mm)

Labels

Feed: Bottom* Only
Weight: Not applicable
Width Range: 3" to 10" (76 to 254 mm)
Envelopes, single feed

Feed: Top Only
Weight: Max. 24 lb.
Width Range: 6.5" to 9.5" (165 to 241 mm)
Envelopes, continuous feed, non-overlap type

Feed: Bottom* Only
Weight: Max. 24 lb.
Width Range: 6.5" to 9.5" (165 to 241 mm)
Card Stock

Feed: Bottom*
Weight: Max. 100 lb. Index (180 g/m2)
Width Range: Not applicable

* Bottom feed requires optional pull or push tractor
Specifications 81

Paper Specifications: ML421
Single (Cut) Sheet

Feed: Top Only
Weight: 14 to 24 lb. US Bond (52.6 to 90 g/m2)
Width Range: 7.2" to 14.3" (182.8 to 363.2 mm)
Single-part, continuous forms

Feed: Rear, Bottom*
Weight: 12 to 24 lb. US Bond (45 to 90 g/m2)
Width Range: 3" to 16" (76.2 to 406.4 mm)
Carbonless continuous forms

Feed: Rear, Bottom*
Weight: 9 to 11 lb.
Width Range: 3" to 16" (76.2 to 406.4 mm)
Interleaf continuous forms

Feed: Rear, Bottom*
Weight: 10 to 12 lb. paper, 9 lb. carbon
Width Range: 3" to 16" (76.2 to 406.4 mm)

* Bottom feed requires optional pull or push tractor
82 Microline 420/421 User’s Guide

Labels

Feed: Bottom* Only
Weight: Not applicable
Width Range: 3" to 16" (76.2 to 406.4 mm)
Envelopes, single feed

Feed: Top Only
Weight: Max. 24 lb.
Width Range: 6.5" to 9.5" (165.1 to 241.3 mm)
Envelopes, continuous feed, non-overlap

Feed: Bottom* Only
Weight: Max. 24 lb.
Width Range: 6.5" to 9.5" (165.1 to 241.3 mm)
Card stock

Feed: Bottom* Only
Weight: Max. 100 lb. Index (180 g/m2)
Width Range: Not applicable

Environmental Requirements

Physical Specifications

Temperature

Note: Height dimensions do not include the acoustic cover.

Operating: 41 to 95°F (5 to 36°C)
Storage: 14 to 122°F (-10 to 50°C)
Humidity

Operating: 20 to 80% RH
Storage: 5 to 95% RH

Electrical Requirements
• 120 volts ac, (+6%, -15%)
50 or 60 Hz (±2%)
58 W Typical, 10 W idle
• 230 ac, (+15%, -14 %)
50 or 60 Hz (±2%)
58 W Typical, 10 W idle

ML420

Size (WxDxH): 17.1" x 16.1" x 6"
(434 x 409 x 153 mm)
Weight: 16.7 lbs. (7.6 kg)
ML421

Size (WxDxH): 23.1" x 16.1" x 6"
(588 x 409 x 153 mm)
Weight: 21.1 lbs. (9.6 kg)

Specifications 83

Appendix D: Installation
Location

Printer

• Place your printer on a firm, solid surface.
• Allow enough space around the printer to easily access the
platen knob and the various paper feed paths.
• Make sure a suitable grounded power outlet is available
nearby.

Ribbon Cartridge
Power Cord

Unpack
• If any items are missing, contact your dealer immediately.
• Keep your packing materials and carton in case you ever
need to ship or transport the printer.
• Interface cable and paper are sold separately.

1 Remove any packing tape, then grasp the tabs (1) at either
end of the access cover and pivot it toward the front of the
printer as far as it will go.

3 Remove the shipping restraint from the pull-up roller
assembly (1).

2 Remove the printhead shipping restraint.

Installation 85

4 Use the tabs (1) to lift and remove the sheet guide, then
remove the shipping restraint.

86 Microline 420/421 User’s Guide

5 Reinstall the sheet guide: insert the clips on either side of the
separator into the notches marked with a triangle, then press
down to secure the separator in place.

Install the Ribbon Cartridge
Important!
Make sure you have the correct replacement ribbon for your
printer. The wrong ribbon will not print when installed in
your printer.

CAUTION! The printhead may be HOT!
3 Unpack the new ribbon cartridge and install it on the
printhead.
Important!
Do not remove the ribbon shield (1) from the ribbon!

Ribbon Cartridge Handling

• Leave unused ribbon cartridges in their packages until
needed.
• Careful; the ribbon ink may cause permanent stains.
• Ribbon ink on skin or clothing can usually be removed with
soap and water.
1 Make sure the printer is turned OFF.
2 Open the access cover and center the printhead (1).

4 Turn the take-up knob (1) in the direction of the molded-in
arrow to take up any ribbon slack.

5 Close the access cover and turn the printer on.

Installation 87

Power Connection

Computer Connections

1 Make sure both the printer and the computer are OFF.
2 Plug the power cord into the back of the printer, then into a
grounded outlet.

Parallel (LPT): IEEE 1284
• Requires bidirectional cable, max. length 6 ft. (1.8 m), not
supplied.
• Printer has 36-pin socket
1 Make sure the printer and computer are both turned off.
2 Attach a suitable bidirectional cable to the parallel connector
on the back of the printer. Then attach and secure the cable
to your computer.

3 Turn on the printer.

3 Turn the printer and computer back on.

88 Microline 420/421 User’s Guide

USB: Specification 1.1 Compliant

Loading Paper

• Requires USB 1.1 cable, maximum length 19.7 ft. (5 m), not
supplied.
• Printer has USB “B” receptacle.

For instructions on loading paper, see “Loading Paper” in
Chapter 5.

1 Make sure the printer and computer are both turned off.
2 Attach a suitable USB cable to the printer. Then attach the
cable to your computer.

3 Turn the computer and printer back on.

Installation 89

Testing the Printer
• Font Sample Test
• Rolling ASCII Test
• Hexadecimal Dump Mode

Font Sample Test

Important!
Wide carriage Model ML421: If you are using 8.5" paper to
run the tests, make sure the paper width selection in the
printer menu is set to 8.5 inches. Otherwise, printing on the
platen may damage the printer. See Chapter 4: Menu Mode
for more information.

90 Microline 420/421 User’s Guide

The Font Sample Test prints a sample of the fonts standard to
the printer.
The top of the printout shows the Printer Model, Emulation,
Country Code, Interface, and Firmware Revision Level.
1 Make sure paper is loaded.
2 Turn off the printer.
3 Press and hold the LF key while turning the printer back on.
The printer prints a page of font samples and the test ends.

Rolling ASCII Test

The Rolling ASCII Print Test produces a continuous printout of
all 96 ASCII characters in a rolling pattern in whatever
typeface is selected (default = LQ Courier).
The top of the printout shows the Printer Model, Emulation,
Country Code, and Firmware Revision Level.

1 Make sure continuous forms paper is loaded.
2 Turn the printer off.
3 Press and hold the QUIET/TOF key while turning the printer
back on. (If the printer comes on without starting the Rolling
ASCII test print, you did not hold the QUIET/TOF key long
enough.)
The printer prints the rolling ASCII text page after page.
4 Press SEL to end the test.

Installation 91

Hexadecimal Dump Mode

Emulations

When the printer is placed in the Hexadecimal Dump Mode, all
data received, including text and printer commands, is printed
in both hexadecimal and ASCII format.

The factory default emulation for your printer is IBM
Proprinter III.

For example, the following line of BASIC code
LPRINT CHR$ (27);”0”;CHR$ (30);”This is an
example of a hexadecimal dump.”

If you wish to change to one of the other emulations, see
“Changing Emulations” in Chapter 3.

Printer Drivers

would print like this:

Note: In the ASCII format, all non-printable characters are
represented by a period.
To engage the Hexadecimal Dump Mode:
1 Make sure paper is loaded.
2 Turn off the printer.
3 Hold the SEL and FF/LOAD keys for several seconds while
turning on the printer.
To exit the Hexadecimal Dump Mode:
• Press the SEL key.
or
• Turn the printer off, then on again.

92 Microline 420/421 User’s Guide

The Oki driver for your printer is provided on the CD included
with the printer. You can either load the Oki driver or select one
of the compatible drivers listed below in your software
application.

Loading the OKI Driver

Using a Compatible Driver

Parallel Interface

Note: See your software documentation for information on how
to select a printer driver.

1 Insert the CD into your CD-ROM drive.
Note: If the CD does not AutoPlay, click Start → Run →
Browse, then browse to your CD-ROM drive,
double-click Install.exe and click OK.

The drivers below are listed by decreasing compatibility with
your printer. Use one as close to the top of the list as possible.

2 Select your printer model.
3 When the Menu Installer window appears, click the Printer
Software button.
4 Follow the on-screen instructions.

• IBM Proprinter III
• IBM Proprinter II
• IBM Proprinter

USB Interface

• Epson FX286e
• Epson FX 850/1050
• Epson FX 800/1000

1 Turn the printer on.
The Windows Add New Hardware Wizard window displays.
2 Click Next.
3 Insert the CD into your CD-ROM drive.
4 Follow the on-screen instructions to install the software for
your printer model.

IBM Proprinter III

Epson FX

Installation 93

Index
A

Accessories ............................................. 68
Alignment problems ................................. 9
ASCII Test .............................................. 91
Auto Carriage return ............................... 35
Auto LF (Line Feed) ........................ 31, 35
Auto Select ............................................. 32

Carbonless continuous forms .......... 81, 82
Card Stock ....................................... 81, 82
Centering printhead position .................. 63
Character Pitch ....................................... 39
Selecting ............................................ 23
Character Set ................................... 28, 36
Character Width ...................................... 39
Characters Per Second (CPS) ................... 7
Code Page Character Set ........................ 36
Codes, Printer Control ............................ 69
Commands
Epson FX ..................................... 72–74
IBM Proprinter III ....................... 69–71
Oki Microline Standard ............... 75–77
Control Codes ......................................... 69
Cut Sheet Feeder..................................... 68

Electrical Requirements .......................... 83
Emulations ....................................... 24, 92
Mode .................................................. 37
Envelopes ........................................ 81, 82
Environmental Requirements ................. 83
Epson FX Commands ....................... 72–74

B
Bar Codes ............................................... 80
Bi-directional printing ..................... 30, 40
Bottom Feed .................................... 81, 82
Form Tear-Off .................................... 29
Line Spacing ...................................... 29
Skip Over Perforation ........................ 29
Buffer
Clearing ............................................. 38
Receive Buffer Size ........................... 78

Factory defaults, menu mode ................. 26
Font Sample Test .................................... 90
Fonts
Embedded Printer Commands ........... 62
Resident ............................................. 80
Selecting ............................................ 40
Forms Tear-Off ....................................... 37
Changing ............................................ 18
Top of Form ................................ 12, 17
Wait Time ........................................... 41
Front Panel
Keys ..................................................... 9
Menu Mode ........................................ 25

Height, Double Height Printing .............. 41
Hex Dump Mode .................................... 92
Humidity ................................................. 83

Labels .............................................. 81, 82
Language ................................................ 28
Length, Page
Rear Feed ........................................... 29
Top Feed ............................................ 30
Limited Operation ...................... 9, 38, 65
Line Spacing ........................................... 38
Bottom Feed ...................................... 29
Rear Feed ........................................... 29
Top Feed ............................................ 30

G
Graphics
Printing ....................................... 30, 37
Resolution .......................................... 80
GROUP, Menu Mode ............................. 25

I
I-Prime ...................................... 32, 38, 61
IBM
Character Set ...................................... 36
Proprinter III Commands ............. 69–71
Initialization string .................................. 61
Interleaf Continuous Forms .................... 82
Interleaf continuous forms...................... 81
Interleaved 2 of 5 .................................... 80
Italics ............................................... 28, 41

M
Margin, Bottom ............................... 30, 36
Mean Time Between Failures (MTBF) .. 78
Mean Time to Repair (MTTR) ............... 78
Memory, Receive Buffer Size ................ 78
MENU light ............................................ 25
Menu Mode ............................................ 25
Changing Settings .............................. 27
Entering ............................................. 26
Exiting ............................................... 26
Front Panel keys ................................ 25
Printing the Menu Settings ................ 26
Reset to factory defaults .................... 26
Settings Table ............................... 28–42
Index 95

O
Oki MICROLINE Standard
Commands ....................................... 75–77
Operator Panel Function ......................... 65
Options ................................................... 66

P
Page Length
Rear Feed ........................................... 29
Top Feed ............................................ 30
Page Width .............................................. 39
Bottom Feed ...................................... 29
Rear Feed ........................................... 29
Setting in the Printer Menu ......... 30, 39
Top Feed ............................................ 30
Paper
Cut Sheet ............................................ 68
Single Sheet ....................................... 53
Static .................................................. 65
Thickness ........................................... 80
Weight ................................................ 82
Widths .................................. 30, 39, 82
Paper Jams ........................................ 64–66
Paper Lever ............................................. 64
Paper Out ................................................ 65
Override ...................................... 30, 39
96 Microline 420/421 User’s Guide

Paper Park ............................................... 18
Paper Path, switching ............................. 19
Parallel Interface ..................................... 32
I-PRIME Signal ................................. 61
Parts, replacement, purchasing ............... 66
Perforation, skip over ...................... 29, 41
Pitch, character ................................ 28, 39
PlatenKnob part number ......................... 67
Postnet .................................................... 80
Power rating.............................................. 3
Print Method ........................................... 78
Print Mode ....................................... 28, 40
Print Registration ............................. 31, 40
Print Server Option ................................. 68
Print Size ................................................ 79
Print Speed ......................................... 7, 79
Print Suppress .................................. 31, 40
Printer Control Codes ....................... 69–77
Printer Drivers, Selecting ................. 92–93
Printer Parameters .................................. 25
Printhead ................................................. 78
Gap ..................................................... 21
Proportional Spacing ....................... 28, 40
Pull Tractor ............................................. 68
Push Tractor ............................................ 68

R
Rear Feed
Continuous Forms .............................. 10
Form Tear-Off ............................. 29, 30
Jams, Repetitive ................................. 56
Line Spacing ...................................... 29
Paper Jam ........................................... 55
Skip Over Perforation ........................ 29
Receive Buffer Size ................................ 78
Reliability ............................................... 78
Replacement Parts .................................. 66
Resolution (Graphics) ............................. 80
Ribbon Cartridge
Replacement Order No. ..................... 67
Replacing ........................................... 42
Ribbon Shield ........................... 43, 63, 87
Roll Paper Stand ..................................... 68
RS-232C Serial Interface ........................ 78

Self Tests ................................................. 90
Serial Interface ........................................ 68
Serial Interface Option ........................... 62
Server, Print Option ................................ 68
Sheet Guide ............................................ 67
Single Sheet
Cut Sheet Feeder Option .................... 68
Jams ................................................... 58
Loading .............................................. 53
Skip Over Perforation ............................. 29
Software
Embedded commands ........................ 62
Matching drivers to emulations ......... 62
Software vs. printer settings .............. 61
Specifications ......................................... 78
Standard Character Set ........................... 28
Symbol Sets ..................................... 28, 38

Temperature Specifications .................... 83
Tests
ASCII Test ......................................... 91
Font Sample Test ............................... 90
Hex Dump .......................................... 92
Thickness, Paper ..................................... 80
Time Out .......................................... 32, 41
Top Feed ........................................... 81–84
Bottom Margin ................................... 30
Line Spacing ...................................... 30
Pull Tractor ........................................ 68
Single Sheet ....................................... 11
Top of Form ............................................ 35
Forms Tear-Off ...................... 8, 12, 17
Paper Shield .................................. 9, 12
Reset to factory default ...................... 16
Setting ................................................ 12
Standard Setting .......................... 12, 16
Typefaces ................................................ 28
Selecting ............................................ 40

Uni-directional printing, graphics .......... 30
Utility
Front Panel Light ............................... 80
Print Speeds ......................................... 7
Utility Mode Print Quality ................. 22

W
Wait Time ........................................ 30, 41
Weight, Paper ......................................... 82
Width
Character ............................................ 39
Double width printing ........................ 41
Page
Bottom Feed .................................. 29
Rear Feed ...................................... 29
Top Feed........................................ 30
Paper .................................................. 82
Setting in the Printer Menu .... 30, 39

Z
Zero character (slashed, unslashed) . 28, 41

Index 97

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