Digital Equipment LA30 N User manual

Order Number: ER-LA30N-SV-003
Service Manual
TM
LA30
N
/LA30
W
Companion Printer

LA30N/LA30W Companion Printer
Service Manual
Digital Equipment Corporation
Maynard, Massachusetts

The contents of this manual may be revised without prior notice.
All Rights Reserved, Copyright © 1996, 1997 Digital Equipment Corporation. Printed in Ireland.
No part of this manual may be reproduced in any form without permission.
Specification No. ER-LA30N-SV
Edition
001
002
003
Date published
January 1996
July 1996
June 1997
Page
–
–
P.4-17,
19, 20,
and 27
and
P.6-2
Revised contents
First issue
LA30W included
Replacement of power supply and ROM
board (cabling and mask ROM mounting)
revised
Replacement of ribbon feed assy added
Recommended Spare Parts List revised
REVISION RECORD

PREFACE
This manual is for engineers who operate, install, or maintain the LA30N/LA30W Companion Printer. The
topics covered are:
Chapter 1: Printer specifications, performance, and configuration
Chapter 2: Unpacking, performance check, and connection
Chapter 3: Troubleshooting
Chapter 4: Maintenance
Chapter 5: Principles of operation
Chapter 6: Spare parts

i
CONTENTS
CHAPTER 1 PRINTER SPECIFICATIONS, PERFORMANCE, AND CONFIGURATION ............1-1
1.1 Overview ...................................................................................................................................................1-1
1.2 Equipment Structure ..................................................................................................................................1-2
1.2.1 Overview .............................................................................................................................................1-2
1.2.2 Model configuration............................................................................................................................1-2
1.2.3 Structure ..............................................................................................................................................1-3
(1) Upper cover assembly ................................................................................................................1-4
(2) Printing mechanism assembly....................................................................................................1-5
(3) Lower cover assembly ...............................................................................................................1-6
CHAPTER 2 UNPACKING, PERFORMANCE CHECK, AND CONNECTION ................................2-1
2.1 Overview ...................................................................................................................................................2-1
2.2 Notes on Installation..................................................................................................................................2-1
2.3 Unpacking..................................................................................................................................................2-2
2.4 Inspection after Unpacking........................................................................................................................2-4
CHAPTER 3 TROUBLESHOOTING ........................................................................................................3-1
3.1 All Indicators Don’t Light .........................................................................................................................3-4
3.2 No Print Head Movement..........................................................................................................................3-6
3.3 Incorrect Printing due to Defective Nonvolatile RAM .............................................................................3-9
3.4 Printing Quality Abnormal ........................................................................................................................3-10
3.5 Forms Feed Abnormal ...............................................................................................................................3-13
3.6 Error Display .............................................................................................................................................3-15
CHAPTER 4 MAINTENANCE ...................................................................................................................4-1
4.1 Overview ...................................................................................................................................................4-1
4.2 Notes on Use..............................................................................................................................................4-1
4.3 Maintenance Tools ....................................................................................................................................4-2
4.4 Maintenance Levels...................................................................................................................................4-2
4.5 Preventive Maintenance ............................................................................................................................4-2
4.6 Parts Drawings...........................................................................................................................................4-3
4.7 Parts That Must Not Be Disassembled ......................................................................................................4-4
4.8 Level 1 Maintenance .................................................................................................................................4-5

ii
4.9 Level 2 Maintenance .................................................................................................................................4-6
4.9.1 Parts replacement ................................................................................................................................4-6
(1) Acoustic cover replacement .......................................................................................................4-7
(2) Tractor unit replacement ............................................................................................................4-8
(3) Cover replacement, including platen knob ................................................................................4-11
(4) Control panel replacement .........................................................................................................4-15
(5) Printing mechanism replacement ...............................................................................................4-16
(6) Power supply and fuse replacement...........................................................................................4-17
(7) RS-423 board replacement.........................................................................................................4-18
(8) ROM board (control board) replacement...................................................................................4-19
(9) Platen roll assembly replacement...............................................................................................4-21
(10) Paper feed motor (LF motor) replacement ................................................................................4-22
(11) Space motor (SP motor) assembly replacement ........................................................................4-23
(12) Sensor T replacement.................................................................................................................4-24
(13) Carriage unit replacement ..........................................................................................................4-25
(14) Print head and ribbon feed assembly replacement.....................................................................4-27
(15) Gear assembly replacement .......................................................................................................4-28
(16) Paper feeder assembly replacement ...........................................................................................4-29
(17) Card guide replacement .............................................................................................................4-30
(18) Ribbon shift unit (color kit) replacement ...................................................................................4-31
4.9.2 Adjustment ..........................................................................................................................................4-32
(1) Print head gap adjustment ..........................................................................................................4-32
(2) Vertical alignment......................................................................................................................4-34
(3) Top-of-forms adjustment (factory use) ......................................................................................4-36
4.9.3 Lubrication ..........................................................................................................................................4-37
(1) Ribbon drive assembly...............................................................................................................4-38
(2) Color ribbon shift motor (option) ..............................................................................................4-39
(3) LF gear bearing and continuous/single lever .............................................................................4-40
(4) Back cover assembly..................................................................................................................4-41
(5) Paper feed roller shaft ................................................................................................................4-42
(6) Shaft ...........................................................................................................................................4-43
(7) Stay shaft....................................................................................................................................4-44
(8) Front and top covers (LA30N)...................................................................................................4-45
(9) Front and top covers (LA30W) ..................................................................................................4-46
(10) Sheet guide assembly ................................................................................................................4-47

iii
4.10 Diagnostics ..............................................................................................................................................4-48
4.10.1 Self-test printing................................................................................................................................4-48
(1) Starting self-test printing............................................................................................................4-48
(2) Checking printer performance ...................................................................................................4-49
(3) Stopping self-test printing ..........................................................................................................4-49
4.10.2 Hex dump ..........................................................................................................................................4-50
(1) Starting hex dump printing ........................................................................................................4-50
(2) Stopping hex dump printing.......................................................................................................4-50
4.10.3 Control panel maintenance functions initiated when power goes on................................................4-51
CHAPTER 5 PRINCIPLES OF OPERATION..........................................................................................5-1
5.1 Overview ...................................................................................................................................................5-1
5.2 Mechanical Operation ...............................................................................................................................5-2
5.2.1 Print head drive ...................................................................................................................................5-2
5.2.2 Carriage drive......................................................................................................................................5-3
5.2.3 Ribbon feed .........................................................................................................................................5-4
5.2.4 Paper feed............................................................................................................................................5-5
(1) Continuous forms feeding ..........................................................................................................5-6
(2) Cut-sheet feeding .......................................................................................................................5-8
(3) Paper selection ...........................................................................................................................5-9
(4) Autoloading................................................................................................................................5-10
(5) Paper end detection ....................................................................................................................5-11
5.2.5 Print head gap control (paper thickness adjustment) ..........................................................................5-14
5.2.6 Color ribbon shift motor (option)........................................................................................................5-15
5.2.7 Option detection mechanism...............................................................................................................5-16
5.3 Electrical Operation...................................................................................................................................5-17
5.3.1 System configuration ..........................................................................................................................5-17
(1) Printer control board (ROM board)............................................................................................5-19
(2) Power supply unit ......................................................................................................................5-19
(3) Sensors .......................................................................................................................................5-19
(4) Control panel..............................................................................................................................5-19
5.3.2 Main controller....................................................................................................................................5-23
5.3.3 Interface control ..................................................................................................................................5-25
(1) Centronics parallel interface ......................................................................................................5-25
(2) RS-423 serial interface...............................................................................................................5-26
5.3.4 Carriage motor control ........................................................................................................................5-27
5.3.5 Print head control ................................................................................................................................5-31
5.3.6 Paper feed control ...............................................................................................................................5-33

iv
5.3.7 Ribbon shift control ............................................................................................................................5-35
5.3.8 Fire check control................................................................................................................................5-37
(1) Short-mode detection...............................................................................................................5-37
(2) Long-mode detection ...............................................................................................................5-37
5.3.9 Control panel control ..........................................................................................................................5-39
5.3.10 Power supply.....................................................................................................................................5-40
(1) Surge current prevention..........................................................................................................5-40
(2) Rectifying and smoothing........................................................................................................5-40
(3) Main voltage regulation switching ..........................................................................................5-42
(4) Protection .................................................................................................................................5-42
(5) External signal .........................................................................................................................5-44
5.4 Firmware Overview...................................................................................................................................5-45
CHAPTER 6 RECOMMENDED SPARE PARTS ....................................................................................6-1

v
ILLUSTRATIONS
Figure 1.1 LA30N and LA30W printers .........................................................................................................1-1
Figure 1.2 Printer component structure ...........................................................................................................1-3
Figure 1.3 Upper cover assembly (LA30N) ....................................................................................................1-5
Figure 1.4 Printer lower assembly (LA30N) ...................................................................................................1-6
Figure 2.1 Unpacking the printer and accessories...........................................................................................2-2
Figure 2.2 Removing the print head shipping restraint (cardboard) ...............................................................2-3
Figure 2.3 Removing the bail stopper and four tapes......................................................................................2-3
Figure 2.4 Installing the cut-sheet stand..........................................................................................................2-4
Figure 3.1 Printer functional block diagram....................................................................................................3-2
Figure 4.1 Basic components ..........................................................................................................................4-3
Figure 4.2 Location of parts that must not be disassembled ...........................................................................4-4
Figure 4.3 Cleaning and lubrication ................................................................................................................4-5
Figure 5.1 Function sequence..........................................................................................................................5-1
Figure 5.2 Print head .......................................................................................................................................5-2
Figure 5.3 Carriage drive.................................................................................................................................5-3
Figure 5.4 Ribbon feed ....................................................................................................................................5-4
Figure 5.5 Paper feed path...............................................................................................................................5-5
Figure 5.6 Continuous form feeding (push-feed tractor).................................................................................5-6
Figure 5.7 Continuous form feeding (pull-feed tractor) ..................................................................................5-7
Figure 5.8 Cut-sheet feeding ...........................................................................................................................5-8
Figure 5.9 Paper selection ...............................................................................................................................5-9
Figure 5.10 Autoloading..................................................................................................................................5-10
Figure 5.11 Paper end detection (cut sheet) ....................................................................................................5-11
Figure 5.12 Paper end detection (continuous forms via push-feed tractor) ....................................................5-12
Figure 5.13 Paper end detection (continuous forms via pull-feed tractor)......................................................5-13
Figure 5.14 Print head gap control ..................................................................................................................5-14
Figure 5.15 Color ribbon shift motor ..............................................................................................................5-15
Figure 5.16 Option detection mechanism........................................................................................................5-16
Figure 5.17 System configuration ...................................................................................................................5-17
Figure 5.18 Connection diagram .....................................................................................................................5-18
Figure 5.19 Controller block diagram .............................................................................................................5-20
Figure 5.20 MB90706 block diagram .............................................................................................................5-21
Figure 5.21 MBCU20050 block diagram ........................................................................................................5-22
Figure 5.22 Memory configuration .................................................................................................................5-23
Figure 5.23 Centronics parallel interface signal timing ..................................................................................5-25
Figure 5.24 RS-423 serial interface signal timing...........................................................................................5-26

vi
Figure 5.25 Stepping motor drive circuit ........................................................................................................5-27
Figure 5.26 Phase switching and carriage drive direction...............................................................................5-28
Figure 5.27 Relationship between carriage drive speed and phase excitation ................................................5-29
Figure 5.28 Carriage drive 1/2-phase excitation at low speed ........................................................................5-30
Figure 5.29 Carriage drive 2-phase excitation at high speed ..........................................................................5-30
Figure 5.30 Print head pin magnet drive circuit ..............................................................................................5-31
Figure 5.31 Print timing ..................................................................................................................................5-32
Figure 5.32 Phase switching and paper feed direction ....................................................................................5-33
Figure 5.33 Paper feed speed...........................................................................................................................5-34
Figure 5.34 1/2-phase excitation of paper feed ...............................................................................................5-34
Figure 5.35 Phase switching and ribbon shift direction ..................................................................................5-35
Figure 5.36 Ribbon shift speed........................................................................................................................5-36
Figure 5.37 Ribbon shift phase excitation .......................................................................................................5-36
Figure 5.38 Fire check circuits ........................................................................................................................5-38
Figure 5.39 Control panel block diagram........................................................................................................5-39
Figure 5.40 Surge current prevention circuit...................................................................................................5-40
Figure 5.41 Power supply block diagram........................................................................................................5-41
Figure 5.42 PWSTOP signal ...........................................................................................................................5-44
Figure 5.43 Firmware configuration................................................................................................................5-45

vii
TABLES
Table 3.1 Errors indicated by the Fault indicator and the buzzer....................................................................3-15
Table 3.2 Alarms that turn power off ..............................................................................................................3-15
Table 4.1 Maintenance tools............................................................................................................................4-2
Table 4.2 Parts not to be disassembled............................................................................................................4-4
Table 4.3 Cleaning...........................................................................................................................................4-5
Table 4.4 Power-on-initiated maintenance......................................................................................................4-52
Table 5.1 Memory address map ......................................................................................................................5-24
Table 5.2 Voltage regulation switching control ..............................................................................................5-42
Table 5.3 Overcurrent protection ....................................................................................................................5-43
Table 5.4 Overvoltage protection ....................................................................................................................5-43

1-1
CHAPTER 1 PRINTER SPECIFICATIONS,
PERFORMANCE, AND
CONFIGURATION
1.1 Overview
This manual is for maintenance engineers, and covers overall maintenance of the Digital LA30N and LA30W
Companion Printers, together with detailed information such as troubleshooting and component replacement.
The information in this manual applies both to the Digital LA30N Companion Printer (80-column printer) and to
the Digital LA30W Companion Printer (136-column printer). However, illustrations are of LA30N Companion
Printer unless otherwise stated.
Recommended references are:
• LA30N/LA30W Companion Printer Illustrated Parts Breakdown (Order Number: ER-LA30N-IP-002)
• LA30N/LA30W Companion Printer User Guide (Order Number: EK-LA30E-UG-001)
The former contains information on location and order number of all parts needed for printer maintenance. The
latter contains general information on printer operation.
The main difference between the LA30N and the LA30W is the “print span”. The LA30N is an 80-column
printer and the LA30W a 136-column printer. As shown in the figures below, the physical specifications are
thus different (size, weight, ...). Some minor differences concern mechanical internal parts that do not impact the
general maintenance of the printer (top cover hinges, bail rollers mechanism, ...). The only visible difference
concerns the accurate location of the notch scale of the paper thickness lever.
LA30N LA30W
Figure 1.1 LA30N and LA30W printers

1-2
1.2 Equipment Structure
1.2.1 Overview
This section outlines printer structure and features.
1.2.2 Model configuration
There are two basic models. The LA30N is an 80-column printer and the LA30W a 136-column printer.
Each model has two optional components: power supply and color kit (color ribbon shift mechanism).
Power supply: factory option
Color kit (consisting of a color ribbon shift mechanism and ribbon): user option
The model configuration varies with the combination of the three options, as follows:
The monochrome model prints in color when the optional color kit is installed.
Each model has three emulations: Digital PPL2, IBM Proprinter X24E and XL24E, and Epson ESC/P2.
Each model is equipped with a dual interface: Centronics parallel and RS-423 serial (to be exact, IEEE 1284
parallel and DEC-423 serial).
Basic models
80 columns
(LA30N)
Print span
136 columns 
(LA30W)
Color
No color kit
Color kit
No color kit
Color kit

100 to 120 VAC
Input voltage
100 to 120 VAC
220 to 240 VAC
220 to 240 VAC No color kit
Color kit
No color kit
Color kit

1-3
1.2.3 Structure
Major printer components are organized as shown below. Items in boldface are recommended spare parts (see
Chapter 6) that can be replaced in the field by maintenance service engineers. Replacement and adjustment are
detailed in Chapter 4.
Upper cover assy
Upper cover
Front cover
Top cover (bail rollers are built in for LA30W)
Acoustic cover [soundproof cover]
Control panel [OP board]
Platen knob
Bail roller unit (LA30N only)
Frame assy
Paper feeder assy (contains feed roller assy)
Platen assy [platen roll assy]
Carriage unit [carrier unit]
Card guide assy (plastic print guide)
Ribbon feed assy
Ribbon shift assy (color kit, option)
Timing belt
Carrier cable assy
Relay cable assy
SP motor assy [space motor assy]
Stay shaft assy
Copy control lever (linked to paper thickness lever )
Sensors
Sensor T assy (for cut-sheet paper end)
Gear assy (paper feed gear system)
Paper feed motor [LF motor]
Paper select lever [change lever]
Print head (consumables)
Ribbon cartridge (black or four-color, consumables)
Printing mechanism [printer mecha assy]
Tractor unit
Printer lower assy
Bottom cover
ROM board [main board with ROM] (also called control board)
RS-423 board
Power supply [power unit] (also called power supply board)
(100-120 or 220-240VAC)
AC inlet assy
Figure 1.2 Printer component structure
LA30N/W printer
Cut-sheet stand [sheet guide sub assy]
Back cover
Note:
[ ] indicates a name referred to in the
Recommended Spare Parts List.
( ) shows additional information.

1-4
(1) Upper cover assembly
The screws (two for the LA30N and three for the LA30W) on the back, fasten the upper cover to the bottom
cover. The upper cover assembly consists of the upper, front, and top covers, an acoustic cover, and a control
panel –– all plastic, lightweight, and sturdy. The cut-sheet stand is mounted on this assembly.
Printer control board
Power supply
Bottom cover
Control panel
Interface connectors (not visible)
Cut-sheet stand
Figure 1.3 Upper cover assembly (LA30N)
a. Upper cover
The interface cable connector is located to the right side, as seen from the front of the upper cover, so that it
does not obstruct the paper feed path.
b. Front cover
The front cover is opened when the ribbon cartridge is installed.
c. Top cover
The separator directs the printed paper to the cut-sheet stand. The separator of the LA30W has bail rollers.
d. Acoustic cover
The acoustic cover helps reduce printing noise.
e. Control panel
The control panel consists of an LSI, 7 switches, 16 LEDs, and a buzzer. The switches control operations
such as forms loading and feeding, font selection, and conditions selected in setup mode. The LEDs display
printer statuses, the selected font, and a setup menu number. The buzzer sounds to indicate operating and
printer statuses.
Upper cover
Stay shaft assy
Platen knob
Top cover assy
Carriage unit
Tractor unit (not visible)
Acoustic cover
Front cover
Space motor
Gear assy

1-5
f. Cut-sheet stand
The cut-sheet stand catches printed pages ejected by the printer. It must be raised while printing cut sheets
and laid down while printing continuous forms. It must also be raised while printing paper-stapled continu-
ous forms in push-tractor mode.
g. Back cover
The back cover, which is installed on the cut-sheet stand, is opened to set continuous forms on the tractor
unit from the back of the printer. It must be closed while the printer is operating.
(2) Printing mechanism assembly
The two hooks on the bottom cover hold the printing mechanism in place and the two screws fasten it to the
bottom cover.
a. Frame assembly
The frame assembly consists of metal plates, a rack rail for ribbon feeding and a paper feed assembly.
b. Carriage unit
The carriage unit supports the removable 24-wire print head and endless inked-ribbon cartridge (black or
four-color), and slides back and forth on the stay shaft. The ribbon feeder (gear system) moves the ribbon in
one direction regardless of carriage movement. The color kit, consisting of a color selection shift motor and
four-color ribbon, is installed on the cartridge. One of the two sensors detects left, right, top, and bottom
edges of paper and the other detects the left end of cartridge movement and information on installed options.
c. Space motor and stay shaft assemblies
The main stay shaft and guide rail support the carriage unit, which the space motor moves horizontally
through the timing belt. The paper thickness lever rotates the eccentric main stay shaft that adjusts the gap
between the print head and platen.
d. Sensors
Three of four sensors detect paper outages and the other detects the paper select lever.
e. Forms feed mechanism
The paper feed motor drives the platen and/or the tractor unit via gears in feeding paper. The paper select
lever switches power transmission to the tractor unit.
f. Tractor unit
The convertible tractor unit is used on the back of the printer as a push tractor and on top of the printer as a
pull tractor.
Bail roller unit (LA30N only)
The bail rollers hold down paper on the platen. For the LA30W, the bail rollers are built in the top cover.

1-6
(3) Lower cover assembly
Figure 1.4 Printer lower assembly (LA30N)
Bottom cover
Printer control board
a. Bottom cover
The bottom cover supports the printer mechanism.
b. Printer control board
The printer control board controls the host interface, control panel, and printing mechanism, using an MPU
and an LSI. Memory holds resident character patterns and firmware, including resident emulation programs.
This board has drivers and receivers for other components. Sensor receivers convert signals from sensors.
Drivers supply power to motors, print head wires, and other components. It also has a Centronics parallel
interface controller and RS-423 serial interface controller.
c. Power supply
The power supply at the front of the printer outputs a constant voltage, regardless of fluctuation in input AC
line voltage, between 100 and 120 VAC or 220 and 240 VAC. It includes an AC line switch and noise filter.
Power supply

2-1
CHAPTER 2 UNPACKING, PERFORMANCE CHECK,
AND CONNECTION
The contents of this chapter are briefly reproduced from the Setting Up Your Printer in the User Guide for
reference in maintenance although the contents are originally for users of the LA30N and LA30W printers.
2.1 Overview
The LA30N and LA30W printers come packed for transportation.
After unpacking and before installation, the printer must undergo self-test printing. Installation requires mini-
mum time and expense.
2.2 Notes on Installation
For best results, note the following points when installing the printer:
• Place the printer on a level, vibration-free surface.
• Keep the printer away from sunlight and heaters.
• Be sure printer ventilation ports are not blocked.
• Do not operate the printer in a humid or dusty environment.
• Use an outlet that is separated from noise-generating equipment such as motors.
• Use the correct AC voltage to avoid unexpected problems.
• Be sure the platen knob is able to turn freely during printer operation. Obstructions may cause incorrect
printing.