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EPSON TERMINAL PRINTER

LQ-300
SERVICE MANUAL




EPSON
NOTICE

All rights reserved. Reproduction of any part of this manual in any form whatsoever without
SEIKO EPSON's express written permission is forbidden.

The contents of this manual are subjects to change without notice.

Alleffortshavebeen made toensuretheaccuracy of thecontentsofthis manual. However, should
any errors be detected, SEIKO EPSON would greatly appreciate being informed of them.

The above notwithstanding SEIKO EPSON can assume no responsibility for any errors in this

manual or the consequence thereof.

Epson is registered trademark of Seiko Epson Corporation.

General Notice: Other product names used herein are foridentication purposes only and maybe
trademarks of their respective carnpanies.




Copyright @ 1994 by SEIKO EPSON CORPORATION Nagano, Japan




-i-
PRECAUTIONS

Precautionary notations throughout the text are categorized relative to 1) personal injury and 2)
damage to equipment.

DANGER Signals a precaution which, if ignored, could result in serious or fatal personal injury.
Great caution should be exercised in performing procedures preceded by DANGER
Headings.

WARNING Signals a precaution which, if ignored, could result in darnage to equipment.

Theprecautionary measures itemized below should alwaysbe observed when performin grepair/
maintenance procedures.

DANGER

1. ALWAYS DISCONNECT THE PRODUCT FROM BOTH THE POWER SOURCE AND
PERIPHERAL DEVICES PERFORMING ANY MAINTENANCE OR REPAIR PROCE-
DURE.

2. NO WORK SHOULD BE PERFORMED ON THE UNIT BY PERSONS UNTAMILIARWITH
BASIC SAFETY MEASURES AS DICTATED FOR ALL ELECTRONICS TECHNICIANS IN
THEIR LINE OF WORK.

3. WHEN PERFORMING TESTING AS DICTATED WITHIN THIS MANUAL, DO NOT
CONNECT THE UNITTOA POWER SOURCE UNTIL INSTRUCTED TO DO SO. WHEN
THE POWER SUPPLY CABLE MUST BE CONNECTED, USE EXTREME CAUTION IN
WORKING ON POWER SUPPLY AND OTHER ELECTRONIC COMPONENTS.

WARNING

1. REPAIRS ON EPSON PRODUCT SHOULD BE PERFORMED ONLY BY AN EPSON
CERTIFIED REPAIR TECHNICIAN.

2. MAKE CERTAIN THAT THE SOURCE VOLTAGE IS THE SAME AS THE RATED VOLT-
AGE, LISTED ON THE SERIAL NUMBER/RATING PLATE. IF THE EPSON PRODUCT
HAS A PRIMARY AC RATING DIFFERENT FROM AVAILABLE POWER SOURCE, DO
NOT CONNECT IT TO THE POWER SOURCE.

3. ALWAYS VERIFY THAT THE EPSON PRODUCT HAS BEEN DISCONNECTED FROM
THE POWER SOURCE BEFORE REMOVING OR REPLACING PRINTED CIRCUIT
BOARDS AND/OR INDIVIDUAL CHIPS.

4. IN ORDER TO PROTECT SENSITIVE MICROPROCESSORS AND CIRCUITRY, USE
STATIC DISCHARGE EQUIPMENT, SUCH AS ANTI-STATIC WRIST STRAPS, WHEN
ACCESSING INTERNAL COMPONENTS.

5. REPLACE MALFUNCTIONING COMPONENTS ONLY WITH THOSE COMPONENTS
BY THE MANUFACTURE; INTRODUCTION OF SECOND-SOURCE Ics OR OTHER
NONAPPROVED COMPONENTS MAY DAMAGE THE PRODUCT AND VOID ANY
APPLICABLE EPSON WARRANTY.




- ii -
PREFACE
This manual describes functions, theory of electrical and mechanical operations, maintenance, and repair
of LQ-300.
The instructions and procedures included herein are intended for the experience repair technician, and
attention should be given to the precautions on the preceding page. The chapters are organized as
follows:

CHAPTER 1. PRODUCT DESCRIPTION
Provides a general product overview, lists specifications, and illustrates the main components of the printer.

CHAPTER 2. OPERATING PRINCIPLES
Describes the theory of printer operation.

CHAPTER 3. DISASSEMBLY AND ASSEMBLY
Includes a step-by-step guide for product disassembly and assembly.

CHAPTER 4. ADJUSTMENTS
Includes a step-by-step guide for adjustment.

CHAPTER 5. TROUBLESHOOTING
Provides Epson-approved techniques for adjustment.

CHAPTER 6. MAINTENANCE
Describes preventive maintenance techniques and lists lubricants and adhesives required to service the equipment.

APPENDIX
Describes connector pin assignments, circuit diagrams, circuit board component layout and exploded diagram.



The contents of this manual are subject to change without notice.




- iv -
f=":

REVISION SHEET

Revision Issue Date Revision Page

Rev. A September 28, 1994 1st issue




.-..>
.$...




.,,

.




-v-


1
TABLE OF CONTENTS


CHAPTER 1. PRODUCT DESCRIPTION
CHAPTER 2. OPERATING PRINCIPLES ..

CHAPTER 3. DISASSEMBLY AND ASSEMBLY
CHAPTER 4. ADJUSTMENTS
CHAPTER 5. TROUBLESHOOTING
CHAPTER 6. MAINTENANCE
APPENDIX




- vi -
CHAPTER 1 Product Description

Table of Contents

1.1 FEATURES 1-1

1.2 SPECIFICATIONS 1-2
1.2.1 Hardware Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
1.2.1.1 Paper Handling Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
1.2.1.2 Paper Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
1.2.1.3 Printable Area... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
1.2.1.4 Ribbon Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
1.2.1.5 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
1.2.1.6 Environmental Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
1.2.1.7 Reliability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
1.2.1.8 Safety Approvals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
1.2.1.9 Physical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
1.2.2 FirmwareS pacifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8

1.3 INTERFACE SPECIFICATIONS 1-11
1.3.1 Paraliellnterface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11
1.3.1.I Compatible Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11
1.3.1.2 Reverse Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-13
1.3.2 Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-14
1.3.3 Interface Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-15
1.3.4 Preventing the Host from Data TransferTimeout . . . . . . . . . . . . . . . . . 1-15

1.4 OPERATING INSTRUCTIONS 1-16
1.4.1 Control Panel Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-16
1.4.2 Self-test Function. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-17
1.4.3 Hexadecimal Dump Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-17
1.4.4 Micro Adjustment Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-18
1.4.5 PrinterStatus Indication.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-18
1.4.6 Selected Font . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-19
1.4.7 Printer Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-19
1.4.7.1 Power-on Initialization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-19
1.4.7.2 Hardware Initialization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-19
1.4.7.3 Software Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-19
1.4.8 PrinterSettings . . . . . . . . . . . . . . . . . . . . . . . .......:. . : . . . . . . . . . 1-20
1.4.8.1 Selectable PrinterSettings . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-20
1.4.8.2 Changing the Default Settings. . . . . . . . . . . . . . . . . . . . . . . . . . 1-20

1.5 MAIN COMPONENTS 1-24
1.5.1 C143 MAIN Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-24
1.5.2 C130PSB/PSE Board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-24
1.5.3 Printer Mechanism (M-5M1O) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-25
1.5.4 Housing Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-25
List of Figures
Figure 1-1. Exterior View of the LQ-300. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 ,':~\
Figure l-2. Pin Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Figure l-3. PrintableAreafor Cut Sheets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
!!.,
Figure l-4. PrintableAreafor Envelopes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Figure l-5. PrintableAreafor Continuous Paper . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Figure l-6. Data Transmission Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11
Figure 1-7. Control Panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-16
Figure l-8. C143 MAIN Board Component Layout . . . . . . . . . . . . . . . . . . . . . . I-24
Figure l-9. C130 PSB/PSE Board Component Layout . . . . . . . . . . . . . . . . . . 1-24
Figure 1-10. Printer Mechanism (M-5 M1O). . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-25
Figure 1-11. Housing Assembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-25



List of Tables
Table l-1. Optional Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Table l-2. PaperThickness LeverSettings . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 -
(:;
Table l-3. Feeding Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Table 1-4. Specifications for Cut Sheet Paper (CSF). . . . . . . . . . . . . . . . . . . . . 1-4
Table 1-5. Specifications for Cut Sheet Paper (Manual Insertion) . . . . . . . . . . . 1-4
Table -6. Specifications forEnvelopes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Table -7. Specifications for Continuous Paper (Single Sheet and Multi-Part) . 1-4
Table -8. Specifications for Continuous Paper with a Label. . . . . . . . . . . . . . . 1-5
Table -9. Electrical Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
Table -lO. CharacterTables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
Table -11. Resolution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9
Table -12. Printing Speed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10
Table -13. Signal and Connector Pin Assignments forthe Parallel Interface. 1-12
Table -14. Signal and ConnectorPin Assignments forthe Parallel Interface. 1-13
Table -15. Signal and Connector Pin Assignments forthe Serial Interface . . 1-14
Table -16. Paper Feeding Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-17
Table -17. Font Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-19
Table -18. Font Lightsand Language Selection . . . . . . . . . . . . . . . . . . . . . . . 1-20
f"~.
Table -19. Default Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-21 ..
Table -20. CharacterTables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-21
Table -21. Page Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-22
Table -22. SkiDOver Perforation/Auto TearOff/AGM/Auto Line Feed
EX~/ACK/ State Reply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-22
Table l-23. Graphic Ptint Direction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-22
Table l-24. Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-22
Tablel-25.interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-22
Table l-26. Bit Rate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-22
Table 1-27. Parity Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-23
Table 1-28. Data Length. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-23
LWOO Service Manual Product Description


1.1 FEATURES
The LQ300 is a small, light-weight, 24pin serial impact dot-matrix color printer suitable for
personal use. The major features of this printer are:
q Fast printing of lo-cpi draft characters at 200 cps
q Compact design saves precious work space
q Easy-to-operate panel
q Quiet printing
q Two built-in 8-bit parallel interfaces and an EIA-232D serial interface
q Printing of up to 66 kes on A4-size or 62 lines on letter-size paper
q Optional color printing using a color ribbon (black, magenta, cyan, yellow)
q Detachable tractor (push, pull, and push-pull tractor feed)
Figure 1-1 shows an exterior view of the LQ-300, and Table 1-1 lists the optional units available for
the LQ-300.

~'"pe'"Q@'



lease
r




Knob

Power s




Sprocket


lever


Center support Tractor unit



Figure 1-1. Exterior View of the LQ-300

Table 1-1. Optional Units

Model Description
#77!53 Ribbon oartridge (monochrome)
#7755 Ribbon oartridge (monochrome, sub-cartridge)
#7768 Ribbon cartridge (film)
S015077 Ribbon oartridge (color)
C80637* Single-bin cut sheet feeder
C83211