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EK-1LA36-MM-001

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Document:	LA36 DECwriter II Maintenance Manual Volume 1
Order Number:	EK-1LA36-MM
Revision:	001
Pages:	406
Original Filename:	http://www.mirrorservice.org/sites/www.bitsavers.org/www.computer.museum.uq.edu.au/pdf/EK-1LA36-MM-001%20LA36%20DECwriter%20II%20Maintenance%20Manual%20Volume%20I.pdf

OCR Text

EK-1 LA36-MM-001

LA36 OECwriter II
MAINTENANCE MANUAL
Volume I

digital equipment corporation • maynard, massachusetts

1st Edition, June 1975
2nd Printing (Rev), September 1976
2nd Edition, June 1977

Copyright © 1975, 1976, 1977 by Digital Equipment Corporation
The material in this manual is for informational
purposes and is subject to change without notice.
Digital Equipment Corporation assumes no respon·
sibility for any errors which may appear in this
manual.
Printed in U.s.A.

This document was set on DIGITAL's DECset-8000
computerized typesetting system.

The following are trademarks of Digital Equipment
Corporation, Maynard, Massachusetts:
DEC
DECCOMM
DECsystem·lQ
DECSYSTEM·20

DECtape
DECUS
DIGITAL
MASSBUS

9/77·14

PDP
RSTS
TYPESET-8
TYPESET· I I
UNIBUS

CONTENTS
Page
CHAPTER 1

GENERAL DESCRIPTION

1.1
1.2
1.2.1
1.2.2
1.2.3
1.2.4
1.2.5
1.2.6
1.2.7
1.2.8
1.2.9
1.2.10
1.3
1.4

PHYSICAL CHARACTERISTICS
FUNCTIONAL DESCRIPTION .
Character Printing .. .
Bell Operation . . . . .
Paper Feeding . . . .
Ribbon Drive System
Carriage Servo System . . . . .
Power Supply . . . . . . . . .
.............. .
Standard Current Loop Interface
.............. .
Optional Half-Duplex (Active or Passive) Current Loop Interface
Peripheral Interface Port
.................. .
Interface Options . . . . . .
TECHNICAL CHARACTERISTICS
OPTIONS . . . . . . . . . . . . .

CHAPTER 2

INSTALLATION AND CHECKOUT GUIDE

2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
2.10

GENERAL . . . . . . . . . . .
UNPACKING AND INSPECTION
.... .
PACKING PROCEDURE . . . . . . . . . .
EASY IDENTIFICATION OF LOGIC BOARDS
INTERF ACE INSTALLATION . . .
M7722 JUMPER CONFIGURATION
M7723 JUMPER CONFIGURATION
M7728 JUMPER CONFIGURATION
LA36 CHECKOUT AND ACCEPTANCE PROCEDURES
LA35 CHECKOUT AND ACCEPTANCE PROCEDURES

CHAPTER 3

OPERATION

3.1
3.1.1
3.1.2
3.1.3
3.1.4
3.1.5
3.1.6
3.1.7
3.1.8
3.1.9
3.1.10
3.1.11
3.1.12
3.1.13

LA36 OPERATOR CONTROLS AND INDICATORS
POWER ON/OFF Switch
LINE/LOC Switch . . .
FDX/HDX Switch .. . .
BAUD RATE Switches
ALT CHAR SET Switch .
CHAR SET LOCK Switch
STD/ ALT CHARACTER SET Indicators .
AUTO LF Switch ..
HERE IS Switch . . . . . .
PAPER OUT Indicator
DEVICE SELECT Indicator
SELECT AVAIL Indicator
CTRLKey . . . . . . . . .

iii

1-3
1-4
1-4
1-5
1-5
1-9
1-10
1-10
1-10
1-12
1-13
1-13
1-14
1-14

2-1
2-3
2-4
2-4
2-5
2-5
2-5
2-5
. 2-13
. 2-13

3-1
3-1
3-1
3-1
3-2
3-2
3-2
3-2
3-2
3-2
3-2
3-3
3-3
3-3

CONTENTS (CONT)
Page
3.1.14
3.1.15
3.1.16
3.1.17
3.1.18
3.1.19
3.1.20
3.1.21
3.1.22
3.1.23
3.1.24
3.1.25
3.2
3.2.1
3.2.2
3.2.3
3.2.4
3.2.5
3.2.6
3.3
3.3.1
3.3.2
3.3.3
3.3.4
3.4
3.4.1
3.4.2
3.4.3
3.4.4
3.4.5
3.5
3.6
3.6.1
3.6.2
3.7
3.7.1
3.7.2
3.7.3
3.7.3.1
3.7.3.2
3.7.4
3.8
3.9
3.10

CAPS LOCK Key
SHIFT Key
TAB Key
ESC (SEL) Key
REPEAT Key .
RETURNKey .
LINE FEED Key
BACKSPACE Key
DELETE Key
BREAK Key . . .
Numeric Keypad
Bell . . . . . . .
LA35 OPERATOR CONTROLS AND INDICATORS
LINE/LOC Switch . . . .
BAUD RATE Switches
PAPER OUT Indicator
POWER ON/OFF Switch
HEAD OF FORM Switch
Bell . . . . . . . . . . .
LA36/LA35 COMMON CONTROLS
Carriage Adjustment Lever
Paper Advance Knob
Tractor Adjust Knob
Cover Interlock Switch
LOADING PAPER AND NEW FORMS
Paper Positioning Procedure .. .
Impression Adjustment . . . . .
Horizontal Positioning Adjustment
Fine Vertical Positioning
Reloading Paper . . . . . . . . . .
RIBBON INSTALLATION . . . . . . .
DECwriter INTERFACE INFORMATION
Interface Description
Interface Specifications . . . . .
PROGRAMMER'S GUIDE . . . . . .
LA36 Programmer's Information
Transmitting Characters and Commands
Special Command Keys . . . . . . .
CTRLKey . . . . . . . . . . .
BREAK Key . . . . . . . . . .
Receiving Characters and Commands
. . . . . . . .
USING THE LA36
USING THE LA35
TROUBLESHOOTING

3-3
3-3
3-3
3-3
3-3
3-4
3-4
3-4
3-4
3-4
3-5
3-5
3-6
3-6
3-6
3-6
3-6
3-6
3-6
3-7
3-7
3-7
3-8
3-8
3-9
3-9
· 3-12
· 3-13
· 3-13
· 3-14
· 3-15
· 3-18
· 3-18
· 3-18
· 3-19
· 3-19
· 3-19
· 3-19
· 3-19
· 3-19
· 3-19
· 3-23
· 3-24
.. 3-24

CONTENTS (CONT)
Page
CHAPTER 4

THEORY

4.1
4.1.1
4.1.2
4.1.3
4.1.4
4.1.5
4.1.6
4.1.7
4.1.8
4.1.9
4.1.1 0
4.1.11
4.2
4.3

4.10
4.11
4.12
4.13
4.14
4.14.1
4.14.2
4.14.3

PROGRAM DESCRIPTION
. . . . .
4-1
Scratch Pad Memory
. . . . .
4-4
Initialize (lNIT) Routine
. .
4-6
Position (POSIT) Routine .
4-8
SERVO Routine . . . . . . . .
. . . . . 4-10
. . . . .
. . . . 4-10
SPEED Routine
INPUT Routine
.....
. . . 4-12
BELL Routine . . . . . . .
. . . . . 4-13
. 4-14
PRINT Routine . . . . . .
LINE FEED (LF) Routine
. 4-16
LCV Routine
. 4-18
......
. 4-18
NEXT Routine
. 4-21
TIMING . . . . . . . . . . . .
M7722/M7723 CONTROL LOGIC
. 4-22
KEYBOARD SYSTEM . . . . . .
. . . . .
. 4-24
DATA COMMUNICATIONS INTERFACE . . . . . . . .
. 4-32
20 rnA Loop Receiver . . . . . . . . . . . . . . . .
. 4-33
20 rnA Loop Driver . . . . . . . . . . . . . . . . .
. 4-33
CLOCK LOGIC . . . . . . . . . . . . . . . . . . . . . . .
. 4-34
UNIVERSAL ASYNCHRONOUS RECEIVER/TRANSMITTER (UART) .. 4-35
. . . 4-37
CHARACTER BUFFER/GENERATOR AND PRINT HEAD SYSTEM
. 4-40
CARRIAGE SERVO SYSTEM . . . . . . . . . . . . . .
Tachometer, Summing Network, and Sum Amplifier . . .
. 4-42
. 4-43
Encoder and Threshold Detector . . . . . . . . . . . . .
. 4-43
Encoder Signal Detector . . . . . . . . . . . . . . . . . .
Column Increment Counter and Carry/Borrow Generator .
. 4-46
BELL SYSTEM . . . . . . . . .
. . . . . .
. . . . . .
. .. 4-47
. . . . 4-47
LINE FEED STEPPER SYSTEM . . . . . . . . . . . . . . . . .
. . . . .
. . . . .
. 4-48
WAKE-UP (WU) CIRCUIT
POWER SUPPLY AND REGULATOR
. 4-49
PRINTER MECHANISM
. . . . .
. 4-49
. 4-50
Carriage Subsystem . . . . . . . . .
Ribbon Feed Subsystem . . . . . . .
. 4-50
. 4-51
Paper Feed Subsystem . . . . . . . .

CHAFfERS

UPGRADED LA36

5.1
5.2
5.3
5.3.1

GENERAL
. . . . . . . . . . . . . . .
LA35/LA36 MODEL VARIATIONS . . . . . .
EASY IDENTIFICATION OF LOGIC BOARDS
Major Functional Differences Between M7722 and M7723
.................. .
Logic Boards
M7722, M7723, and M7728 Jumper Configurations

4.4
4.5
4.5.1
4.5.2
4.6
4.7
4.8

4.9
4.9.1
4.9.2
4.9.3

4.9.4

5.3.2

5-1
5-1
5-1
5-2
5-2

CONTENTS (CONT)
Page
5.3.3
5.3.4
5.4
5.4.1
5.5
5.6
5.7
5.8
5.8.1
5.8.2
5.8.3
5.8.4

Functional Differences Between M7723 and M7728 Logic Boards
M7728 Cabling Configurations/Option Combinations
MAJOR POWER SUPPLY CHANGES
New Power Transformers
NEW KEYBOARD BEZELS
CAPS LOCK KEYBOARD
LA35/LA36 OPTIONS
DECwriter II - M7728 FUNCTIONAL DESCRIPTION
New Transmit Path
New Receive Path . . . . . . . . . . . . .
Transmit Operation with Options Installed
Receive Operation with Options Installed

CHAPTER 6

ELEcrRICAL SERVICING

6.1
6.1.1
6.1.1.1
6.1.1.2
6.1.1.3
6.1.1.4
6.1.1.5
6.1.2
6.1.2.1
6.1.2.2
6.1.3
6.2

ELECTRICAL TESTS . . .
Off-Line Tests . . . .
Encoder Signal Processing Test
Servo Speed Test
..... .
Line Feed (LF) Stepping Test
Bell Test . . . . . . . .
Printable Character Test '"
On-Line Tests . . . . . . . . . . .
Current Loop Interface UART and Character Buffer Test
Serial Line Interface . . . . . . . . . . .
Wake-Up Test . . . . . . . . . . . . . . . . .
TROUBLESHOOTING CHARTS (ON-LINE TESTS)

CHAPTER 7

MECHANICAL SERVICING

7.l
7.2
7.2.1
7.2.2
7.3
7.3.1
7.3.2
7.4
7.4.1
7.4.2
7.5
7.5.l
7.5.2
7.6
7.6.l

GENERAL . . . . . . . . .
PRINTER HOUSING
Printer Housing Removal
Printer Housing Installation
PRINT HEAD ASSEMBLY
Print Head Removal .
Print Head Installation
TIMING BELT . . . . . .
Timing Belt Removal
Timing Belt Installation
CARRIAGE ASSEMBLY AND CARRIAGE SHAFTS
Carriage Assembly and Carriage Shafts Removal
Carriage Assembly and Carriage Shaft Installation
CARRIAGE BUSHING AND CARRIAGE LEVER
Carriage Bushing and Carriage Lever Removal . .

5-2
5-3
5-4
5-4
5-4
5-4
5-4
5-4
5-6
5-6
5-6
5-8

6-1
6-1
6-2
6-11

6-19
6-23
6-25
. 6-37
6-37
6-40
6-42
6-43

7-1
7-1
7-1
7-5
7-5
7-5
7-6
7-9
7-9
7-9
7-10
7-10
7-12
7-14
7-14

CONTENTS (CONT)
Page
7.6.2
7.7
7.7.1
7.7.2
7.8
7.8.1
7.8.2
7.9
7.9.1
7.9.2
7.10
7.1 0.1
7.10.2
7.11
7.11.1
7.11.2
7.11.3
7.12
7.12.1
7.12.2
7.13
7.13.1
7.13.2
7.14
7.14.1
7.14.2
7.15
7.15.1
7.15.2
7.16
7.16.1
7.16.2
7.17
7.17.1
7.17.2
7.18
7.18.1
7.18.2
7.19
7.19.1
7.19.2
7.20
7.20.1
7.20.2

Carriage Bushing and Carriage Lever Installation
RIBBON DRIVE ASSEMBLY . . . . . .
Ribbon Drive Assembly Removal
Ribbon Drive Assembly Installation
RIBBON DRIVE FAFNIR BEARING
Ribbon Drive Fafnir Removal . . .
Ribbon Drive Fafnir Installation
RIBBON ECCENTRIC WITH CLUTCH/BACKSTOP SPRING
Ribbon Eccentric with Clutch/Backstop Spring Removal
Ribbon Eccentric with Clutch/Backstop Spring Installation
RIBBON DRIVE PULLEY . . . . .
Ribbon Drive Pulley Removal . . . .
Ribbon Drive Pulley Installation
DC MOTOR .\ND ENCODER ASSEMBLY
DC Motor and Encoder Assembly Removal
DC Motor and Encoder Assembly Installation
Encoder Electrical Adjustment
PRINTER MECHANISM ASSEMBLY
Printer Mechanism Assembly Removal
Printer Mechanism Installation
TRACTOR DRIVE SHAFTS AND TRACTOR ASSEMBLIES
Tractor Drive Shaft and Tractor Assembly Removal
Tractor Drive Shaft and Tractor Assembly Installation
RIBBON CHASSIS ASSEMBLY. . . . .
Ribbon Chassis Assembly Removal . . . . . . . . . .
Ribbon Chassis Assembly Installation . . . . . . . . .
RIBBON SPOOL RATCHET WHEELS AND FRICTION DISKS
Ribbon Spool Ratchet Wheel(s) and Friction Disk Removal
Ribbon Spool Ratchet Wheel(s) and Friction Disk Installation
PRINT BAR . . . . . . .
Print Bar Removal ..
Print Bar Installation
IDLER GEAR ASSEMBLY
Idler Gear Assembly Removal
Idler Gear Assembly Installation
STEPPING MOTOR ASSEMBLY. .
Stepping Motor Assembly Removal
Stepping Motor Assembly Installation
TRANSFORMER ASSEMBLY . . . . . .
Transformer Assembly Removal . . .
Transformer Assembly Installation Procedure
LINE FILTER ASSEMBLY AND FUSE HOLDER
Type 1 Line Filter and Fuse Holder Removal
Type 1 Line Filter and Fuse Holder Installation

vii

7-15
7-16
7-16
7-17
7-18
7-18
7-20
7-20
7-20
7-20
7-21
7-21
7-21
7-22
7-22
7-23
7-23
7-26
7-26
7-27
7-29
7-29
7-29
7-31
7-31
7-31
7-32
7-32
7-33
7-34
7-34
7-35
7-37
7-37
7-37
7-38
7-38
7-38
7-39
7-39
7-43
7-44
7-44
7-44

CONTENTS (CONT)
Page
7.20.3
7.20.4
7.21
7.21.1
7.21.2
7.22
7.22.1
7.22.2
7.23
7.23.1
7.23.2

Type 2 Line Filter and Fuse Holder Removal . . . . . . . . . . . . . . 7-45
Type 2 Line Filter and Fuse Holder Installation . . . . . . . . . . . . . 7-45
LK02, LK03 KEYBOARD ASSEMBLY AND FRONT PANEL ASSEMBLY . 7-45
Keyboard and Front Panel Assembly Removal . . . . . . . . . . . . . 7-45
LK02 Keyboard Assembly Installation . . . . . . . . . . . . . . . . . 7-46
POWER BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-50
. . . . .
. . . . . . .. .. 7-50
Power Board Removal.
Power Board Installation
. . . . . . . . . . . .
. . . 7-50
LOGIC BOARD . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . 7-51
Logic Board Removal . . . .
. . . . . . . . ..
. 7-51
Logic Board Installation . . . . . . . . . . .
. . . . . . . . . . . . 7-51

CHAPTER 8

ADJUSTMENT PROCEDURES AND LUBRICATION

8.1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
8.9
8.10
8.11
8.12

GENERAL . . . . . . . . . .
. . . . .
. . . . .
8-1
ENCODER ADJUSTMENT . . . . . . . . .
. . . . .
8-1
PRINT HEAD ADJUSTMENT . . . . . . . . .
. . . . .
8-4
CARRIAGE SHAFT ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . 8-6
PRINT BAR ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . 8-9
PAPER GUIDE AND PRINTER MECHANISM ADJUSTMENT . . . . . . . 8-11
PAPER OUT SWITCH ADJUSTMENT . . . . . . . . . . . . . . . . . . . . 8-13
RIBBON TENSION ADJUSTMENT
. . . . . . . . . . . . . . . . . . . . . 8-13
RIBBON DRIVE ASSEMBLY ADJUSTMENT . . . . . . . . . . . . . . . . 8-16
IDLER GEAR ASSEMBLY ADJUSTMENT
.....
. . . . . . . . . 8-18
BUMPER ASSEMBLY ADJUSTMENT
. 8-19
LUBRICATION . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . 8-20

APPENDIX A

ENGINEERING DRAWINGS

APPENDIXB

ILLUSTRATED PARTS BREAKDOWN

APPENDIXC

REFERENCE DATA

C.l
C.2
C.3

ABBREVIATIONS
..... .
SIGNAL GLOSSARY . . . . . .
IC PIN LOCATION DRAWINGS

. . . . . . . . . . . . ..

C-l
C-l
C-l

FIGURES
Figure No.
1-1
1-2
1-3
1-4
1-5

Title

Page

Outline Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Simplified Functional Block Diagram . . . . . . . . . . . . . . . . . .
1-4
Current Loop Cable Connector Pin Designations . . . . . . . . . . . . . . . 1-10
Standard Current Loop Interface . . . . . . . . . . . .
. . . . . . .. 1-11
Optional Current Loop Configurations . . . . . . . . . . . . . . . . . . . . 1-12
viii

FIGURES (CONT)
Figure No.
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9
2-10
2-11
2-12
4-1
4-2
4-3
4-4
4-5

4-6
4-7
4-8
4-9
4-10
4-11
4-12
4-13
4-14
4-15
4-16
4-17
4-18
4-19
4-20
4-21
4-22
4-23
4-24
4-25
4-26
4-27
4-28
4-29
4-30
4-31
4-32

ntle
LA36 Site Considerations
LA35 Site Considerations
DECwriter Packaging
Cable Tie Location
Physical Characteristics of M7722, M7723, and M7728 Logic Boards
DECwriter Current Loop Cable Connection . . . .
DECwriter DEClO Current Loop Cable Connection
DECwriter EIA Logic Board Connection
Acoustic Coupler Cable Connection . . . . .
Location of Jumpers on M7722 Logic Board
Location of Jumpers on M7723 Logic Board
Location of Jumpers on M7728 Logic Board
Microprogram Flow Diagram
INIT Routine . . . . . . .
POSIT and START Routines
SERVO Routine
SPEED Routine
INPUT Routine
BELL Routine .
PRINT Routine
LINE FEED Routine
LCV Routine
NEXT Routine
Control Logic Block Diagram
LK02/LK03 Keyboard Logic Diagram
.....
Keyboard Timing Diagram
Data Communications Interface Diagram
Data Communications Interface Timing Diagram
20 rnA Loop Receiver Diagram
20 rnA Loop Driver
Clock Logic . . . . . . . . . .
Clock Timing Relationship
UART/Mode Selection and Baud Rate Selection Logic
Character Buffer/Address Register/Generator and Print Head System
CG ROM Character Cell
Print Head Operation
Carriage Servo System .
Tachometer Logic . . .
Encoder and Threshold Detector
Encoder Signal Detector . . . . .
Increment Detection Timing
Encoder Signal Detector and Column Increment Counter Timing Diagram
Column Increment Counter and C/B Generator Logic
Bell System Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ix

Page
2-1
2-1
2-2
2-3
2-4
2-6
2-7
2-8
2-9
2-10
2-11
2-12
4-2
4-7
4-9
4-10
· 4-11
· 4-12
· 4-13
· 4-15
· 4-17
· 4-18
· 4-19
· 4-23
· 4-25
· 4-31
· 4-32
· 4-32
· 4-33
· 4-33
· 4-34
· 4-34
· 4-36
· 4-38
· 4-39
4-40
· 4-42
· 4-43
· 4-44
· 4-44
· 4-45
4-46
· 4-47

FIGURES (CONT)
Figure No.
4-33
4-34
4-35
4-36
4-37
4-38
4-39
5-1
5-2
5-3
5-4
5-5
5-6
5-7
6-1
6-2
6-3
6-4
6-5
6-6
6-7
6-8
6-9
6-10
6-11
6-12
6-13
6-14
6-15
6-16
6-17
6-18
6-19
6-20
6-21
6-22
6-23
6-24
6-25
6-26
6-27
6-28
6-29
6-30
6-31

Title

Page

Line Feed Stepper System .
Line Feed Timing Diagram
Power Supply Block Diagram
LA36 Printing Principle
Carriage Subsystem
Ribbon Feed Subsystem
Paper Feed Subsystem .
Physical Characteristics of M7722, M7723, and M7728 Logic Boards
Cabling Configurations for the M7728 Logic Board
LA36 Keyboard Bezel ., . . . . . . . . .
Basic Block Diagram of M7728 Logic Board
..... .
M7728 Control Logic Diagram
Steering of Keyboard Data . . . . . . . .
Receive Operations of M7728 Logic Board
Encoder +21 V Test Setup
Encoder - 21 V Test Setup
+PTland +PT2 Waveforms
+PT1 and +PT2 Schmitt Waveforms
+INC and COUNT Flip-Flop Waveforms
COUNT Flip-Flop and COUNT Pulse Waveforms
COUNT Flip-Flop and CLR ± Flip-Flop Waveforms
+INC Waveform . . . . . .
+TACH Waveform . . . . . . . . .
- PT1 and - PT2 Waveforms
- PT1 and - PT2 Schmitt Waveforms
- INC and COUNT Flip-Flop Waveforms
- INC Waveform . . . . . . . . . .
- TACH Waveform . . . . . . . . . . .
- INC and 76 JlS CLOCK Waveforms ..
- TACH Waveforms at Q 12-Band Q 12-C
-TACH and 76 JlS Waveforms . . . .
-TACH and SUM Waveforms at J1-B
-TACH and MD Waveforms . . . . .
INC Waveform . . . . . . . . . . . .
COL INC COUNT 3 (MSB) and COL INC COUNT 2 Waveforms
COL INC COUNT 3 (MSB) and BORROW H Waveforms
+INC and 76 JlS Waveforms . . . . . .
+TACH and 76 JlS Waveforms . . . . .
+TACH Waveforms at Q11-B and Q11-C
+TACH and SUM Waveforms . . . . .
+TACH and MD Waveforms . . . . . .
COL INC COUNT 3 (MSB) and CARRY H Waveforms
LF Motor Phase 1 and Phase 2 Waveforms
..... .
LF1 Waveform at TPA12 and LF2 Waveform at TPA15
LF1 Waveform at TPA13 and LF2 Waveform at TPA16

· 4-47
· 4-48

· 4-49

· 4-49
· 4-50
· 4-51
· 4-51
5-2
5-3
5-4
5-5
5-7
5-8
5-9
6-3
6-4
6-5
6-5
6-6
6-6
6-7
6-7
6-8
6-8
6-9
6-9
6-10
6-10
6-12
6-12
6-13
6-13
6-14
6-14
6-15
6-15
6-16
6-16
6-17
6-17
6-18
6-18
6-19
6-20
6-20

FIGURES (CONT)
Figure No.
6~32

6-33
6-34
6-35
6-36
6-37
6-38
6-39
6-40
6-41
6-42
6-43
6-44
6-45
6-46
6-47
6-48
6-49
6-50
6-51
6-52
6-53
6-54
6-55
6-56
6-57
6-58
6-59
6-60
6-61
6-62
6-63
6-64
6-65
6-66
6-67
7-1
7-2
7-3
7-4
7-5
7-6
7-7
7~

ntle
LFI Waveform at TPA14 and LF2 Waveform at TPA17
LF Motor Common Return and LF HOLD Waveforms
LFI Waveform at 11-11 and LF2 Waveform at JI-P
LFI Waveform and LF HOLD Waveforms
BELL Source and BELL SINK Waveforms
BELL SINK and BELL Waveforms
KBH H Pulse Waveforms
HD EN and SOL Waveforms at J6
HS 1 and SD 1 Waveforms
HSI and SDI Waveforms
HSI and SDI Waveforms
HSI and SDI Waveforms
HD EN and HS 1 Waveforms at J 1
HD EN and BUFF HEAD EN H Waveforms
HD EN Voltage Waveform and SD Current Waveform
WRITE BUFF Land CLR R DONE Waveforms
KEY STB L Waveform
Power Board V REF Waveform
CLK Hand 592 ns Waveforms .
592 ns and 1.184 J,lS Waveforms
9.4 J,lS and 76 J,lS Waveforms .
9.4 J,lS and 19L J,lS Waveforms
18.8 J,lS and 76 J,lS Waveforms
18.8 J,lS and 4.8 kHz Waveforms
208 Hand 4.8 kHz Waveforms
37.6 J,lS and 1.76 kHz Waveforms
M7728 Option Clock Waveform
Current Loop Test Setup
Loop Receiver Waveforms
Loop Driver Waveforms .
Serial Line Test Setup ..
Serial Output and Serial Input Waveforms
Wake-Up Waveform . . . . . . . . . . .
Example of Lost Position (reduced 50 percent)
Print Head Solenoid Resistance Measurement
Typical Voltages for Power Supply Regulators
Assembly Removal Sequence
Printer Housing Removal
Power Board Connectors
Prin t Head Removal .
Print Head Cable
Print Head Adjustment
Belt Tension Spring Location
Carriage Shaft Screw Access .

Page
6-21
6-21
6-22
6-22
6-23
6-24
6-24
6-26
6-26
6-27
6-27
6-28
6-29
6-30
6-30
6-31
6-31
6-32
6-32
6-33
6-33
6-34
6-34
6-35
6-35
6-36
6-36
6-38
6-39
6-39
6-41
6-41
6-42
6-53
6-54
6-55
7-2
7-3
7-4
7-5
7-6
7-7
7-9
7-10

FIGURES (CONT)
Figure No.
7-9
7-10
7-11
7-12
7-13
7-14
7-15
7-16
7-17
7-18
7-19
7-20
7-21
7-22
7-23
7-24
7-25
7-26
7-27
7-28
7-29
7~30

7-31
7-32
7-33
7-34
7-35
7-36
7-37
7-38
7-39
7-40
7-41
7-42
7-43
7-44
8-1
8-2
8-3
8-4
8-5
8-6
8-7
8-8

TItle

Carriage Shaft Removal . . . . . .
Printer Mechanism End Plate Loosening
Carriage Shaft Parallelism/Alignment
Plain Bushing and Spring Replacement
Carriage Lever and Eccentric Bearing Replacement
Ribbon Drive Assembly Removal
Ribbon Drive Adjustment .. .
Fafnir Bearing Removal . . . .
Ribbon Drive Shaft Adjustment
DC Motor/Encoder Cabling ..
DC Motor/Encoder Removal
Encoder 50 Percent Duty Cycle Waveshape
Encoder (Rear View) . . . . . . . . .
Encoder Phasing Adjustment . . . . .
Printer Mechanism Removal Preparation
Printer Mechanism Removal ..
Printer Mechanism Alignment . . .
Printer Mechanism Adjustment
.....
Tractor Removal
Tractor Phasing/Adjustment
Ribbon Chassis Removal
Ribbon Threading/Drag Test
Friction Disk/Ratchet Wheel Replacement
Print Bar Removal .. . . . . . . . .
Calibrate Alignment Gauge and Block
Print Bar Alignment . . . . .
Idler Gear Assembly Removal
Stepping Motor Removal
Transformer Removal
.....
Capacitor C5
Rocker Switch S 1
Type 2 Filter Assembly Removal
Keyboard Bezel Removal
LK02 Keyboard Removal . . . .
LK03 Keyboard Removal . . . .
LK03 Keyboard and Control Pad Removal
Encoder 50 Percent Duty Cycle Wave Shape
Encoder (Rear View)
Encoder Phasing Waveshape
Print Head Adjustment
Timing Belt Removal
Carriage Shaft Parallelism/Alignment
Alignment Gauge and Calibration Block
Print Bar Adjustment . . . . . . . . .

xii

Page

· 7-11
· 7-11
· 7-13
7-15
7-15
7-16
7-18
7-19
· 7-19
· 7-22
· 7-22
7-24
7-24
7-25
7-26
7-26
7-28
· 7-28
· 7-29
· 7-30
· 7-31
· 7-32
· 7-33
· 7-34
· 7-35
· 7-36
· 7-37
7-38
· 7-39
· 7-41
· 7-42
7-45
· 7-46
· 7-47
· 7-48
· 7-49
8-2
8-3
8-4
8-5
8-7
8-8
8-9
8-10

FIGURES (CONT)
Figure No.

8-9
8-10

8-il
8-12
8-13
8-14
8-15
8-16
8-17
8-18
8-19
8-20

TItle

Page

Printer Mechanism Alignment .
Printer Mechanism Adjustment
Paper Guide Adjustment
PAPER OUT Switch Adjustment
Ribbon Spool Tension Adjustment
Ribbon Threading/Drag Test
Ribbon Drive Adjustment
Ribbon Drive Assembly . .
Idler Gear Assembly . . . .
Bumper Assembly Adjustment
Carriage Shaft Lubrication
Ribbon Drive Assembly Lubrication

8-11
8-12
8-12
8-13
8-14
8-15
8-16
8-17
8-18
8-19
8-20
8-20

TABLES
Table No.

1-1
1-2
1-3
1-4
1-5
1-6
1-7
1-8
1-9
3-1
3-2
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8

6-1
6-2
6-3
6-4

6-5
8-1
B-1
B-2

Title

Page

Standard ASCII Character Set and Code
.......... .
ASCII Codes and Responses . . . . .. . . . . . . . . . . .
Standard Full-Duplex 20 rnA Current Loop Cable Connections
Optional Half-Duplex 20 rnA Current Loop Cable Connections
Interface Port Connector Pins .
Technical Characteristics
Current Interface Specifications
LA36 Options . . . . . . .
LA35 Options . . . . . . . . .
ASCII Codes and Responses . .
Operator's Troubleshooting Guide
Scratch Pad Allocations . .
SPEED Algorithm . . . . . . . .
Keyboard ROM Addressing
Numeric Keypad ROM Addressing
Oock Frequencies and Time Periods
Baud Rate Switch Connections
MPC SPEED Command Truth Table
LF Pulse Truth Table . . . . . .
Test Equipment and Special Tools
UARTTest . . . . .
Character Buffer Test
Troubleshooting Chart
DC Supply Voltages .
Lubrication Points . .
Glossary of Abbreviations
Signal Glossary
.....

1-2
1-6
1-11
1-13
1-13
1-14
1-16
1-17
1-20
3-20
3-24
· 4-5
· 4-10
· 4-25
· 4-31
· 4-35
· 4-37
· 4-41
· 4-48
6-1
6-25
6-25
6-44
6-54
8-20
B-2
B-5

xiii

TRACTOR
ADJUSTMENT

PAPER
ADVANCE

CARRIAGE ADJUSTMENT
LEVER

OPERATOR
CONTROLS

LA36/ LA35 DECwriter

CHAPTER 1
GENERAL DESCRIPTION

The LA36/LA35 DECwriter II is a fast, small, quiet 300 baud printer terminal for use as an economical hard-copy terminal in remote or local output or input/ output applications. A true 30-character-persecond throughput is provided for full utilization of a 300 baud communications line without the use
offill characters. Data can be Sent (LA36) or received (LA36/LA35) in standard ASCII code at 3 rates:
110, 150, and 300 baud.
NOTE
This manual should be used to maintain LA37s. The
LA37 is an LA36 with a APL/ ASCII keyboard.
The printer produces a hard copy original plus up to 5 duplicate copies on tractor-driven continuous
forms varying in width from 7.6 to 37.8 cm (3 to 14-7/8 inches). Preprinted forms can be positioned in
exact vertical alignment by operating a manual clutch on the tractor drive. The standard set of 96
upper- and lowercase ASCII characters (Table 1-1) is printed at a horizontal spacing of 3.9 characters
per centimeter (10 characters per inch) and a vertical spacing of 2.3 lines per centimeter (6 lines per
inch). A switch on the LA36 keyboard printed circuit board allows selection of a reduced set of 64
uppercase ASCII characters.
NOTE
On LA36 printers with serial numbers below 15700,
this switch is internal. On units above 15700, this
switch is accessible to an operator and is called keyboard CAPS LOCK key.

1-1

Table 1-1 Standard ASCII Character Set and Code

COL2 COL)

III

1
1

COLlI COLS COLb COL?

84838281

10 10 0

.I :I.

('.',

C'l

(.)

..:)

(""I
' ...

t:)

"(\

(.)

\,J

"..

(.)

(2)

'.1

\2)

(2)

}

(2)

. ..
'X
\

:11:

'_J

(:.

C,.

::)

'l'.., ·4 II T 1..1 'l',
%
. ..••••-:J r'.._. u (:.j 1..1
,.}

r'.. 'v'

\.\

i.
I_J

7 G t.1..l d w
(:('5 H 1\ ,•...I ..',.
..-; I Y :1.. ...
.
. ....1 Z
••••
.- 1 ::..

••• 1

(
)

"'I

I-{ r.. II.. -{
f._ \ :I. II

....

.....

M ] m }

'0,
'

()

+ y
t

,'.

0'
'"

.
..

Iii

,...

....

1"1

DEL

1-2

1.1 PHYSICAL CHARACI'ERISTICS
The unit is a free-standing, pedestal-type terminal. Dimensions are shown in Figure 1-1. There are two
major mechanical assemblies and three circuit boards in the unit. Mechanical assemblies are the printer mechanism and print head, which are mounted on a cabinet base. A complete mechanical breakdown of the DECwriter II is provided in Appendix B.
Electronic components are mounted on a keyboard assembly, logic board, and a power board. The
logic board, which contains all logic control function parts, is mounted on the rear door of the cabinet
to simplify access during maintenance. The power board, which contains all power amplifier, driver,
and dc power supply and regulator parts, is mounted against the rear wall of the cabinet. Large
components, such as the power transformer and filter capacitors, are mounted on the base of the
cabinet. The line cord enters at the base of the cabinet. A fan mounted inside the cabinet provides
forced-air cooling. Low-voltage, high-energy terminals are protected against accidental shorts by
fuses.

LA35/LA36

l'l:'~:J]

LA36

rFrO>

!frO>
33.5"
(852mm)

---,

33.5 "
(852m m)

L- 21.7"~
(551mm)

L24.0"

(610mm)

25.0"
(635mm)

~
CP-1571

Figure 1-1

Outline Dimensions

1-3

1.2 FUNCTIONAL DESCRIPTION
A functional block diagram is shown in Figure 1-2. The DECwriter II prints by moving a 7-wire print
head horizontally along the print line, firing the individual wires at the appropriate times to produce a
7 X 7 dot matrix character.
The print head travels on a carriage system and is connected to the drive system by a timing belt. A
reversible dc servo motor provides the drive power for the print head and for the ribbon drive mechanism. An encoder on the motor produces feedback pulses that are used by the logic to keep track of the
print head position.
Line feeding is accomplished by a pin-feed tractor system that is driven by a stepping motor through a
simple gear mechanism.
A microprogrammed controller (MPC) is used to control the printer.

SET/CLR BEL
BELL
SYSTEM

2.4 KHz

CRYSTAL
CLOCK

\1.6896MHZ

LINE FEED
STEPPER
SYSTEM

LF/LF HOLD

MICROPROGRAMMED
CONTROLLER
(MPC)

CARRY I BORROW INCREMENT
SPEED DATA ~
DATA BUSvI

CHARACTER
ADDRESS
DATA
COMMUNICATIONS
INTERFACE
SERIAL
INPUT

RECEIVE
LOOP

I
I

-,
J
r --"- ------I
I
L_
I
SERIAL
OUTPUT

TRANSMIT
LOOP

¢-

I
CARRIAGE
SERVO
SYSTEM

:
I

A
T
A
B

r--~
I

~
UA RT
CHARACTER BUFFER

-.....,

ADDRESS REGISTER

CG ROM

RIBBON
DRIVE
SYSTEM

I
I

oo.M'~

PRINT HEAD
SYSTEM

---,

I
-~
I
I
I
I
LA36 ONLY
IL ______________
..JI
STROBE

COLUMN INCREMENT COUNT

KEYBOARD
SYSTEM

CP-1378

Figure 1-2 Simplified Functional Block Diagram

1.2.1 Character Printing
At power-up, the print head is moved slowly to the left until it hits the end stop. This point is used as a
reference by the MPC to determine the location of the printed line. The first print column is set about
3.8 mm (0.15 inch) to the right of the end stop.
1-4

Incoming characters from the keyboard system (LA36) or the data communications interface are
placed in a 16-character read/write FIFO '(first-in, first-out) buffer. Under normal operation, the
buffer will never overflow; however, in case of overflow, the most recently received character is lost.
Detection of printable characters and decoding of control characters is performed by the MPC based
on information stored in the character generation ROM (read only memory). This allows the implementation of arbitrary character sets simply by changing the ROM.
In the standard ASCII character set, there are 95 character codes that are interpreted as printable. For
each of these characters, the carriage servo system is commanded to move through one character cell.
The print head solenoids are energized each 0.25 mm (0.01 inch) of motion to form the 7 columns of
the 7 3 7 dot matrix for the character. The 96th character code (delete) is a nonprinting, nonspacing
control code.
Four additional codes are interpreted by the MPC: carriage return (CR), line feed (LF), backspace
(BS), and bell (BEL). The remaining 28 ASCII codes are nonprinting, nonspacing control codes that
cause no operation in the printer.
Carriage return and backspace operations are described in Paragraph 1.2.5. Line feed operation is
described in Paragraph 1.2.3.
Table 1-2 identifies the 7-bit ASCII codes generated by the LA36 keys and the responses of the
LA36/LA35 to all incoming codes.
1.2.2 Bell Operation
Receipt of the bell character causes an audible tone to be produced. A separate tone burst is produced
from each of up to eight bell codes received in succession.
If the keyboard has been active during the printing of a line, the audible tone is generated when the
carriage passes the 64th character position.

1.2.3 Paper Feeding
The LA36 is designed for pin-feed paper up to 378 mm (14.875 inches) wide. The hole spacing along
the edge is 12.7 ± 0.254 mm (0.500 ± 0.010 inch) [non-accumulative over 0.508 mm (2.0 inches)] with a
hole diameter of 3.81 to 4.064 mm (0.150 to 0.160 inch). Multipart forms of up to six sheets (and five
carbon sheets) may be used, with a maximum allowable total thickness of 0.508 mm (0.020 inch),
which is measured at about 20 Ib/in2 pressure. Card stock of one layer may be used, with a maximum
thickness of 0.254 mm (0.010 inch). Multipart forms may have only one card part; the card must be the
last part. A print head gap control (Figure 3-1) is provided for the operator to adjust for the thickness
of various forms, which range from 0.0762 to 0.508 mm (0.003 to 0.020 inch).
A full 279.4 mm (11 inch) high box of paper may be placed under the rear of the printer stand. The
paper is fed through a slot under the mechanism. Loading can be facilitated by opening the head gap to
maximum with the printer cover open. Special attention should then be given to readjusting the head
gap to the corresponding paper thickness setting as directed in Chapter 3, Paragraph 3.2.1. The feed
holes of the paper are engaged by 2 tractors of 11 pins each after passing through the print station.
Supports are provided for the incoming and outgoing paper to prevent interference.
The drive tractors may be adjusted horizontally to register properly for any form with hole spacing in
the casework, and are provided with a knob for manual paper advance. The shaft is driven through a
reduction gear by a stepper motor. Each line feed operation advances the paper 4.2 mm (1/6 inch). This
is performed in 33 ms, maximum, either singly or in succession. Consequently, the paper feed rate is
127 mm (5 inches or 30 lines) per second.

1-5

Table 1-2 ASCII Codes and Responses
KEYBOARD OPERAnONS
To Transmit, Type Key(s) (LA36)
ASCD Code

Character

SHIFT*

CTRL*

CHAR

000

NUL
SOH
STX
ETX
EaT
ENQ
ACK
BEL
BS
HT
LF
VT
FF
CR
SO
SI
DLE

V
V
V
V
V
V
V
V

SPACE
A
B
C
D
E
F
BELL
H
I
J
VT
FF
M
N
a
P
Q
R
S
T
U

001
002
003
004

005
006
007
010
011
012
013
014
015
016
017
020
021
022
023
024
025
026
027
030
031
032
033
034
035
036
037
040

V
V
V
v'

V
V
V
V
V

DCl
DC2
DC3
DC4
NAK
SYN
ETB
CAN
EM
SUB
ESC
FS
GS
RS

US
SP

V
V

Character
Printed

Action/Description

None

None
~

~j,

None
Sound Alann Bell
Backspace one position
None
Advance Paper one line
None
None
Move print head to left margin
None
411~

V
W

V
V

[
\

V
V
V
V

RECEIVE OPERAnONS

'"
-

space bar

None
Blank Spacd

None
Print character, move print head
one position to the right.

*A check in this column indicates the key (SHIFT or CTRL) that must be held down while the character key is typed.
If both keys are checked, then both keys must be held down.

1-6

Table 1-2 ASCII Codes and Responses (Cont)
RECEIVE OPERATIONS

KEYBOARD OPERATIONS
To Transmit, Type Key(s) (LA36)
CHAR

Character
Printed

"
#

V
V
V
V

(
)

0
1
2
3
4
.5
6
7

0
1
2
3
4
5
6
7

8
9

;

<
=
>

ASCnCode

Character

SHIFf*

041
042
043

"
#

044

045
046
047
050
051
052
053
054
055
056
057
060
061
062
063
064
065
066
067
070
071
072
073
074
075
076
077

V
V
V
V
V
V

(
)

*
+
,

CTRL*

Action/Description
Print character, move print head
one position to the right.

2
3
4
5
6
7

V
,

<
=
>
?

100
101

102
103
104

A
C
D

V
V
V
V
V
V

V
V

Print character, move print head
one position to the right.

*A check in this column indicates the key (SHIFT or crRL) that must be held down while the character key is typed.
If both keys are checked, then both keys must be held down.

1-7

Table 1-2 ASCII Codes and Responses (Cont)
KEYBOARD OPERATIONS
To Transmit, Type Key(s) (LA36)

RECEIVE OPERATIONS

CHAR

Character
Printed

F
G

H
I

J
K
L

ASCllCode

Character

SHIFT··

105
106
107
110
111
112
113
114
115
116
117
120
121
122
123
124
125
126
127
130
131
132
133
134
135
136
137
140
141
142
143
144
145
146
147
150

F
G

CTRL·

Y
Y
Y
Y
Y
Y

N
0
P

R
S
T

Y
Y
Y
Y
Y
Y
Y

R
S
T

Y
V
Y
Y
Y

V
W

H
I

J
K

X
Y

s
T

w
X

z
]

Z
[
\
]

[

]

Y
V

A
B

c
d
e
f

g
h

C
D
E
F

G
H

Action/Description
Print character, move print head
one position to the right.
... ~

c
d
e
f

g
h

... ~

Print character, move print head
one position to the right.

*A check in this column indicates the key (SHIFT or CfRL) that must be held down while the character key is typed.
If both keys are checked, then both keys must be held down.

1-8

Table 1-2 ASCII Codes and Responses (Cont)
RECEIVE OPERATIONS

KEYBOARD OPERATIONS
To Transmit, Type Key(s) (LA36)
ASCnCode

151
152
153
154
155
156
157
160
161
162
163
164
165
166
167
170
171
172
173
174
175
176
177

Character

SmFT*

i
j
k

crRL*

CHAR

Character
Printed

I
J
K

j
k

1
m
n

M
N

Print character, move print head
one position to the right.

1
m
n
0

0
P

r
s
t

R
S

r
s
t

T
U
V

v
w

x
Y
z

I
I

DEL

vi
vi
vi

v
w

X
Y
Z

Action/Description

y
z
I

DELETE

None

...

Print character, move print head
one position to the right.
None

*A check in this column indicates the key (SHIFT or CfRL) that must be held down while the character key is typed.
If both keys are checked, then both keys must be held down.

1.2.4 Ribbon Drive System
A 36.576 m (40 yard) long, 12.7 mm (0.5 inch) wide ribbon is wound upon two 101.6 mm (3-1/4 inch)
diameter spools. Two rivets are provided in the ribbon, one near each end, to serve as a reversing
tripper.
Power from the carriage drive motor moves the ribbon through a drive belt, a one-way clutch and a
reversing mechanism. The clockwise motion of the motor during printing is used to drive the ribbon;
no ribbon motion occurs during carriage return. The drive is always connected to one of the two
spools. The connecting mechanisms are controlled by a power shift which is triggered by the reversing
sensors. As one spool empties, the rivet on the ribbon pushes a lever into the path of a shift tab which
flips the ratchet from one reel to the other. Ribbon tension is maintained by drags composed of springloaded disk brakes on each spool hub.
1-9

1.2.5 Carriage Se"O System
The carriage servo system is a dc servo mechanism that contains a power amplifier driving a conventional permanent-magnet dc motor which drives the carriage through a timing belt. The movement of
the motor shaft and, hence, the position of the carriage is detected by an optical incremental encoder
which produces one pulse for each 2.54 mm (0.01 inch) of carriage motion.
A one-decade, up/down BCD (binary-coded decimal) counter keeps track of the carriage position
within a character space. The overflow of this counter is monitored by an MPC and is used to determine the carriage position and for other control functions. The speed of the motor during printing,
carriage return, and LCV (last character visibility) is controlled by the MPC by means of a register
which in turn controls the output voltage of the power amplifier feeding the motor.
Printing is accomplished by moving the print head from left to right across the space to be occupied by
the character. When a BCD counter indicates that the carriage is at a given dot position, the appropriate solenoids are energized to print. If the carriage is to the right of the starting position for the
character, the carriage is moved to the left of the starting position before printing commences. If there
is a second printing character in storage while a character is being printed, the carriage speed is
increased to catch up. When printing is complete, the carriage stops.
When a backspace character is received, the carriage is moved to the left a distance of one character
cell [2.54 mm (0.1 inch)]. This function allows character overprinting without an intervening carriage
return.
When a carriage return character is received, the carriage is moved to the left-hand margin. Carriage
speed is a function of the distance between the carriage and the left-hand margin. The time required to
return the carriage to the margin is compensated for by an accelerated print rate until no more than
one character is in the buffer.
When approximately 2 seconds have elapsed without a printable character input, the carriage moves 4
character spaces to the right to permit the operator to see the last character. When printing is to be
resumed, the carriage moves to the left to begin printing.
1.2.6 Power Supply
The main power supply is an unregulated supply with nominal output voltages of +21 Vdc and -21
Vdc. The minimum instantaneous output voltage is 15 V for full load and minimum line voltage.
The 5 V supply for the logic has a regulation of ±5 percent with 200 mY peak-to-peak maximum
ripple.
Regulated volts of +12 V ±5 percent and -12 V ±5 percent, with 500 mY peak-to-peak maximum
ripple are provided for operational amplifier and MOS (metal oxide semiconductor) circuits. A -9 Vdc
regulator is included on the logic board when the PROM (programmable read only memory) option is
supplied.
1.2.7 Standard Current Loop Interface
NOTE
The LA36 and LA35 have identical interfaces.
However, the LA35 only utilizes the receive
circuitry.
The standard interface is a full-duplex, passive
20 mA current loop similar to a Teletyp~ interface. The cable pin connections are shown in
Table 1-3 (polarities denote current flow) and
Figure 1-3. Circuit operation is shown in Figure
1-4 (polarities denote current flow).

8
CP-1I615

@Teletype is a registered trademark of Teletype Corporation.

1-10

Figure 1-3 Current Loop Cable
Connector Pin Designations

Table 1-3 Standard Full-Duplex 20 mA Current Loop Cable Connections
Connector Pin Numbers
To Logic Board
Connector J3

To Host Computer
Connector

Pl-2

Circuit

Description

P2-3

Transmi t (+)
(keyboard)

Negative side
of line

Pl-5

P2-7

Transmit (- )
(keyboard)

Positive side
of line

Pl-3

P2-2

Receive (+)
(printer)

Negative side
of line

Pl-7

P2-5

Receive (-)
(printer)

Positive side
of line

LA36
PASSIVE RECEIVER

HOST (COMPUTER)
ACTIVE TRANSMITTER
CURRENT
SOURCE
XMIT

INTERFACE
CABLES
UP TO
R~C
1500 FT 7

~r----~
7r- - --~

20 MA
LOOP
RCVR

I----___e+-... PRINTER
3

'---J>.IiI'r---tf--4" I

______ JI SEE
NOTE

TRANSMITTED
DATA

PASSIVE TRANSMITTER

ACTIVE RECEIVER
RECEIVED

DATA~---

---,

REC

I----I~r

..----I~r

- - ~r

REC

~r-

20MA
LOOP
__X_M_T....,R.....-_ FROM
KEYBOARD

CURRENT
SOURCE

CP-l1l7

NOTE: Loop ,witches or. trani,tor,.

Figure 1-4 Standard Current Loop Interface

1-11

Typing each specific key causes the LA36 transmitter switch to be opened and closed in a pattern that
defines the key.
The 20 rnA communications circuit will operate wherever the current source is located. A device is said
to be active if it supplies the current for the communications loop and passive if it receives current from
another device.
The LA36 is shipped with a 20 rnA cable (BC05F) to interface the terminal as a passive device to a
computer, or to another peripheral device that is operating as an active device.
1.2.8 Optional Half-Duplex (Active or Passive) Current Loop Interface
In the half-duplex mode, transmission between two devices can take place in only one direction at a
time; however, no keyboard lockout is provided. Any ofthe configurations shown in Figure 1-5 can be
obtained by using jumpers on the DECwriter II logic boards; the jumpers can be changed as described
in Chapter 2, Paragraph 2.5.4. The configurations on the left of Figure 1-5 show the LA36 used as an
active device, providing its own current source; the configurations on the right show the DECwriter II
used in the half-duplex mode, both as a passive and an active device.
Cable pin connections are shown in Table 1-4.
The active connection defeats the isolation of signal line and local circuits, requiring that appropriate
protective measures, such as high potential breakdown grounds (lighting arrestors, etc.) be installed on
the signal line and that care be taken to ensure that protective (frame) ground is connected.
HALF DUPLEX
(PASSIVE)
ACTIVE TRANSMIT

-1

RECEIVE DATA r--.....L._-,
TO PRINTER

~-}TO

pASSIVE
1MI\ RECEIVER
XMIT DATA

~R~M ~E.!.~~~D___"

r
_

XMIT DATA
FROM KEYBOARD ~ SEE NOTE

TO
} ACTIVE HALF

DUP". PO",

SEE NOTE

+-=,"v..

*
HALF DUPLEX
(ACTIVE)

ACTIVE RECEIVE

~}TO
REC

PASSIVE
TRANSMITTER

-~~------~~~'----~L
_
~_

+
RECEIVE DATA r--.....L._..,

RECEIVE DATA
TO PRINTER

TO PRINTER

TO
} PASSIVE
HALF
DUPLEX PORT

r--........- - ,

XMIT DATA
FROM KEYBOARD,

..---_-'~."...___""_'1....J SEE NOTE
+J::

NOTE: Loop switches are transistors.

Figure 1-5 Optional Current Loop Configurations
1-12

CP-1164

Table 1-4 Optional Half-Duplex 20 mA Current Loop Cable Connections
Connector Pin Numbers
To Logic Board
Connector 13

To Host Computer
Connector

Pl-S

PI-3

Circuit

Description

P2-3

Transmi t (+)
(keyboard)

Negative side
of line

P2-S

Receive (-)
(printer)

Positive side
of line

1.2.9 Peripheral Interface Port
The LA36/LA35 has a connector for non-current loop interfaces. The connection is via a straight 8pin Mate-N-Lok connector, J4, with the pin designations listed in Table 1-5.
The interface using this port is physically mounted within the cabinet.

1.2.10 Interface Options
The LA36 is capable of functioning with several different interfaces (options).
Tables 1-8 and 1-9 provide a general description of each interface option. For detailed information,
refer to the appropriate chapter in Volume 2 of this manual.

Table 1-5 Interface Port Connector Pins
Pin

Function

Unused

-12 V, up to 125 rnA to optional in terface

+12 V, up to 125 rnA to optional interface

+5 V, up to 500 rnA to optional interface

Serial output of LA36 to optional interface
TTL level, will drive 10 unit loads.

Mechanical keying
connection).

Serial input to LA36 from optional interface
TTL level (must be capable of driving 10
unit loads).

Ground

1-13

plug (no

electrical

1.3 TECHNICAL CHARACTERISTICS
The technical characteristics of the LA36 DECwriter II are listed in Table 1-6. The interface specifications for the LA36 serial 20 rnA current loop are shown in Table 1-7.
1.4 OPTIONS
The basic LA36 DECwriter II can be expanded to provide the user with a number of function options
for receiving, transmitting, and handling data. These functional options are described in Tables 1-8
and 1-9.

Table 1-6 Technical Characteristics
Main Specifications
Printing Speed
Number of Columns
Printing Characters
Control Characters
Keyboard Characters

30 char/sec throughput, serial asynchronous
132
96 ASCII/character set (95 + DELETE)
32 ASCII/character set
128 (LA36)

Printing
Type
Character Size
Vertical Spacing
Horizontal Spacing
Carriage Return
Line Feed
Slew Speed (paper feed rate)

Impact 7 X 7 dot matrix
0.175 X 0.25 cm (0.70 X 0.100 in)
2.36 lines/cm (6 lines/in)
3.94 char/cm (10 char/in)
500 ms, maximum
33 ms
1.97 cm/sec (5 in/sec) (30 lines/sec)

LA36 Keyboard

Standard ASCII typewriter-like layout, mechanical contact
with four parallel switches.

Transmission Rates

110 baud II bit; I start bit, 7 character bits, 1 parity bit, and 2
stop bits. 150 and 300 baud 10 bit; 1 start bit, 7 character bits, 1
parity bit, and 1 stop bit.

Modes of Operation

Local or full-duplex on-line, switch-selectable at keyboard
panel

Parity

None

Interface

Integrated 20 rnA current loop, full-duplex passive operation;
connectors are 8-pin Mate-N-Lok type.

Power

90-132 Vac, 180-264 Vac, 48-63 Hz, or 50/60 Hz ± 1 Hz (see
note)
300 W, maximum (printing)
160 W (idle)

Ribbon

DIGITAL-specified nylon fabric, spool assembly 12.7 mm (0.5
in) wide ± 36.576 m (40 yards) long
Order No. 36-10558
1-14

Table 1-6 Technical Characteristics (Cont)
Paper
Variable Width
Single-Part

7.62 to 37.78 cm (3 to 14-7/8 in)
6.8 kg (15 lb) paper. minimum
Card stock thickness of 0.25 mm (0.010 in). maximum

Multipart

2- to 6-part (see Notes)
Thickness of 0.50 mm (0.020 in). maximum
Tractor-drive. pin-feed
NOTES
1. Multipart forms may have only one card part. The card must be
the last part.
2. NCR or 3M paper, up to 6-part, must use ribbon on top copy.
First surface impact paper is not recommended.
3. Continuous-feed, fan-fold business forms with 3- or 4-prong
margin crimps on both margins (multipart) are recommended.
Stapled forms are not recommended and may damage tractors
and other areas of the machine. Dot or line glue margins are
acceptable (if line is on one margin only). Do not line glue both
margins as air will not be able to escape and poor impressions
will result.

Mechanical
Mounting
LA36 Size
LA35 Size
LA36 Weight
LA35 Weight

Free-standing pedestal unit
851 mm (33.5 in) H X 699 mm (27.5 in) W X 607 mm (24 in) D
851 mm (33.5 in) H X 699 mm (27.5 in) W X 550 mm (21.7 in) D
46 kg (102 lb)
44.09 kg (97 Ib)

Environment
Temperature

Operating: 10 0 to 40 0 C (50 0 to 104 0 F)
Non-operating: -40 0 to 66 0 C (-40 0 to 151 0 F)

Relative Humidity

Operating: 10 to 90% with a maximum wet bulb temperature of
28 0 C (82 0 F) and a minimum dew point of 2 0 C (36 0 F).
noncondensing
Nonoperating: 5 to 95%

Altitude

Operating: sea level to 3.04 km (8000 ft)

Ribbon

DIGITAL-specified nylon fabric. spool assembly 12.7 mm (0.5
in) wide ± 36.576 m (40 yards) long
Order No. 36-10558
NOTE
50/60 Hz is applicable to printers with CVT transformers. This
transformer can be identified by the capacitor mounted on top of
the transformer frame.
1-15

Table 1-7 Current Interface Specifications
Transmitter (passive, isolated, goes to "mark" state when power is turned off)
Minimum
Open circuit voltage (of circuit being driven)
Voltage drop, marking
Spacing current
Marking current
Receiver (passive, isolated)
Voltage drop, marking
Spacing current
Marking current

Maximum

5.0V
0.5V
0.4 rnA
20 rnA

40V
2.0V
2.0 rnA
80 rnA

Minimum

Maximum

1.2 V
0.0 rnA
15mA

2.7V
3.0mA
80 rnA

Minimum

Maximum

1.7 V
0.0 rnA
15mA

4.7V
3.0 rnA
80 rnA

Cable
4-conductor
Standard 28.1 cm (15 ft) BC05F-15 supplied with LA36
Cable extension is 4920 m (1500 ft), maximum
Receiver /Transmitter (active/half duplex)
Voltage drop, marking
Spacing current
Marking current

NOTE
Standard configuration is passive transmitter and
receiver. Active/half duplex are optional configurations. These configurations are jumper selectable. (See Paragraph 2.5, Interface Installation.)

1-16

Table 1-8 LA36 Options
Control
Switch/Indicator

Description

Options

Name

LAXX-LB

Expander Option

None

The Expander Option Mounting Kit
includes the logic, cables, and mounting hardware required to expand the
LA36 to include options LAXX-LA,
LAXX-KV, LAXX-KW, LAXX-KX,
LAXX-KY, and LAXX-PK.

LAXX-PK

APLI ASCII Dual
Character Set

ALT CHAR SET,
CHAR SET LOCK,
and STD/ALT
CHARACTER SET
Indicators

This option provides an APL alternate character set for use with the
standard character set in the LA36.

LAXX-LA

Auto LF After CR

AUTO LF

When the AUTO LF switch is activated, the printer will automatically
insert a line feed after each carriage
return code typed during transmission. The LAXX-LA option can also
be configured to execute a line feed
after each received carriage return
code. Any combination of these
options can be used.

LAXX-LM

Acoustic Coupler

Carrier Detect Lamp

The acoustic coupler provides an
interface between a telephone and the
DECwriter.

LAXX-KV

Top of Forms
Control

FORMS LENGTH
Switch and SET TOP
OF FORM
Pushbutton

Controls mounted under the top cover
provide the operator with a method of
selecting the length of the paper to be
used. After the desired setting is
selected and the paper is lined up for
proper vertical alignment, the operator presses the SET TOP OF FORM
switch so that the internal logic will be
preset to the paper length defined by
the operator.

1-17

Table 1-8 LA36 Options (Cont)
Options

Name

Switch/Indicator

Description

LAXX-KW

Selective
Addressing

DEVICE SELECT
and SELECT AVAIL
Lamps

The Selective Addressing Option
allows the LA36 to communicate with
other terminals on a single data communications channel.

LAXX-KX

Auto Answerback
and Auto LF
Options

HERE IS, AUTO LF

The Automatic Answerback Option
allows the terminal to transmit a preprogrammed message of 20 characters
(maximum). The message is initiated
by pressing the HERE IS pushbutton,
or upon receipt of the ENQ control
code from another device. The
LAXX-KX also incorporates the features of the Auto LF Option (LAXXLA).

LAXX-KY

Forms Control and
Vertical and
Horizontal Tabs

Keyboard Keys

The Forms and Tabbing Option
enables the terminal to set horizontal
and vertical tab positions either locally or via the system software. This
option also incorporates features of
the Top of Forms Option (LAXXKV) and operates in the same manner.

LAXX-LG

EIA/CCITT
Interface

None

The LAXX-LG interface provides the
user with an RS/232-C interface with
modem control and includes a 3.54 m
(9 ft) cable terminated with a standard
EIA connector.

LAXX-KH

OF!! Mounting Kit

None

The DFll Mounting Kit enables the
user to mount one of the DIGITAL
series OF!! communication options
in the LA36.

1-18

Table 1-8 LA36 Options (Cont)

OptiORS

Name

S~teb/lnlUcator

Description

LAXX-KJ

Compressed Font
Option

None

The Compressed Font Option is a
mechanical option that provides the
LA36 with the ability to print 132 columns on a form 21.59 cm (8-1/2 inches) wide.

LAXX-KK

14-Key Numeric
Keypad

Keyboard Keys

The 14-key numeric keypad is located
to the right of the keyboard and provides the operator with a convenient
method of entering mathematical
number sequences.

LAXX-LZ

Paper Out

PAPER OUT Lamp

Provides a visual indication for a
paper-out condition. Prevents keyboard and received data from
printing.

LAXX-LH

Current Loop Cable

None

20 mA current loop with Mate-NLok.

LAXX-LK

Current Loop Cable

None

20 mA current loop with 4-pin plug
for DEClO.

LAXX-KG

EIA Interface

None

The LAXX-KG interface includes a
3.54 m (9 ft) cable terminated with a
standard EIA connector (no modem
control features).

LAXX-LN

Scale, Pointer, and
Window Kit

Column Scale, Line
Indicator, and
Column Pointer

Operator convenience items that assist
in positioning the print head on preprinted forms and in locating horizontal tabs.

1-19

Table 1-9 LA3S Options
Option

Description

Name

LAXX-LB

Expander Option
Mount

The Expander Option Mounting Kit includes the logic,
cables, and mounting hardware required to expand the LA35
to include options LAXX-LA, LAXX-KV, LAXX-KW,
LAXX-KX, LAXX-KY, and LAXX-PK.

LAXX-PK

APL/ ASCII Dual
Character Set

This option provides an APL alternate character set for use
with the standard character set in the LA35.

LAXX-LA

Auto LF After CR

The LAXX-LA option causes the printer to execute a line
feed after each received carriage return code.

LA~-KV

Top of Forms
Control

Controls mounted under the top cover provide the operator
with a method of selecting the length of the paper to be used.
After the desired setting is selected and the paper is lined up
for proper vertical alignment, the operator presses the SET
TOP OF FORM switch so that the internal logic will be preset to this paper length as defined by the operator.

LAXX-KW

Selective
Addressing

The Selective Addressing Option allows the LA35 to operate
with other terminals on a single data communications
channel.

LAXX-KX

Auto Answerback
and Auto LF
Options

The Automatic Answerback Option allows the terminal to
transmit a preprogrammed message of 20 characters (maximum). The message is initiated upon receipt of the ENQ
control code from another device. The LAXX-KX may be
configured to incorporate the features of the Automatic Line
Feed Option (LAXX-LA).

LAXX-KY

Forms Control,
Vertical and
Horizontal Tabs

The Forms and Tabbing Option enables the printer to set
horizontal and vertical tab positions via the system software.
This option also incorporates features of the Top of Forms
Option (LAXX-KV) and operates in the same manner.

1-20

Table 1-9 LA35 Options (Cont)
Option

Description

Name

LAXX-LM

Acoustic Coupler

The acoustic coupler provides an interface between a telephone and the DECwriter.

LAXX-LG

EIA/CCITT
Interface

The LAXX-LG EIA/CCITT interface provides the user with
an RS232-C interface with modem control and includes a
3.54 m (9 ft) cable terminated with a standard EIA connector.

LAXX-KH

DFll Mounting Kit

The DFll Mounting Kit enables the user to mount one of the
DIGITAL series DFll communication options in the LA35.

LAXX-KJ

Compressed Font
Option

The Compressed Font Option is a mechanical option that
provides the LA35 with the ability to print 132 columns on a
form 21.59 cm (8-1/2 inches) wide.

LAXX-LC

TTL TO CCITT
(V28 Converted and
Modem Protector

The TTL to CCITT (V28) converter and modem protector is
a BPO DATEL services interface that meets the requirements
of CCITT (V28), with BPO-required modem protection
circuitry.

LAXX-LH

Current Loop Cable

20 rnA current loop with Mate-N-Lok

LAXX-LK

Curent Loop Cable

20 rnA current loop with 4-pin plug for DEClO

LAXX-KG

EIA Interface

The LAXX-LG interface includes a 3.54 m (9 ft) cable terminated with a standard EIA connector.

LAXX-LN

Scale, Pointer, and
Window Kit

These are operator convenience items that assist in positioning the print head on preprinted forms and for locating horizontal tabs

1-21

CHAPTER 2
INSTALLATION AND CHECKOUT GUIDE

2.1 GENERAL
This paragraph contains the step-by-step procedures for unpacking and unit checkout to ensure that
the unit was not damaged during shipment and that the unit is operating properly prior to connection
to the communication system.
The DECwriter should be installed in an area that is free of excessive dust, dirt, corrosive fumes, and
vapors. To ensure that the unit has proper ventilation and cooling, the ventilation openings on the side
of the cabinet should not be obstructed. A minimum 10.2 cm (4 inch) clearance between units must be
maintained at all times. Adequate service clearance must also be provided for servicing the unit. (Refer
,
to Figures 2-1 and 2-2.)

i(696mmJ
27.5"

t - - - 24"

=:=l

rF~

--( m")

(S52mm)

-..,

mm)

(33. 5")
(S51

L--250"~

21.7"
( 551mm)

-J

(635mm)

I---S

L--25.0·~
(63!5mm)

:--SER~ICE--l
I
I

AREA

I
I

I--E
[J--...

~F~~~====~~L--

* CURRENT LOOP CABLE (BC05F) LENGTH
IS 15 FT ; EJA CABLE LENGTH IS 9 FT
(2744mm)

* CURRENT LOOP CABLE (BC05F) LENGTH IS

15 FT ; EIA CABLE LENGTH IS 9FT

(Z744mmJ

I
SERVICE
I
:
AREA
I
L __________ J
Cp·ZOZ3

Figure 2-1

I
I

I
I
SERVICE
I
AREA
I
I
L __________ J
CP-2021

LA36 Site Considerations

Figure 2-2
2-1

LA35 Site Considerations

FULL
TELESCOPE
CAP

--_w

STITCHED
TUBE

POLYBAG

---_-..I

WOOD BRACE

HEX HEAD BOLTS
MICROFOAM

WOOD SKID

POLYBAG

TEE NUTS

CP-2187

Figure 2-3

DECwriter Packaging

2-2

2.2 UNPACKING AND INSPECTION
The following procedure outlines the steps required for unpacking and inspecting the DECwriter.
1. Cut the nylon retaining straps from around the shipping carton and discard them.
2.

Remove the outer cardboard shipping container.

3. Remove all shock-absorbing material and packing from around the DECwriter (Figure 2-3).
4.

Remove the poly bag from the printer.

Remove the foam key protector pad from the keyboard (LA36).

Loosen and remove the hex-head bolt securing the wooden leg brace to the skid assembly.
Remove the micro foam from around each leg of the DECwriter.

7. Carefully inspect the DECwriter cabinet, keyboard, and carriage assembly for possible shipping damage. Inspect and check the enclosed packing list for lost or missing items. Report
any damage or missing items to the local DIGITAL Field Service Office or Sales Office and
to the local carrier.
8.

Remove the printer from the wooden shipping skid and place it in the desired location.

9. Lift the DECwriter top cover assembly; clip and remove the nylon cable tie securing the
print head assembly (Figure 2-4). Remove the caution tag.

CABLE
TIE
7555-10

Figure 2-4

Cable Tie Location
2-3

10. Install and adjust the leveling feet on the DECwriter legs.
11. If necessary, wipe all outer surfaces with a clean, soft, lint-free cloth.
12. Connect the interface cable to the user's equipment. (See the DECwriter Interface
Information. )
NOTE
Site pllUlS are not supplied by Digital Equipment
Corporation. Interface logic connections must be
specified and provided by tbe system supplier or the
customer because each installation may be different.
2.3 PACKING PROCEDURE
If it becomes necessary to ship your DECwriter to another location, repack it per the following
procedure.
1. Remove the ribbon and paper.
2. Using a nylon cable tie, secure the print head assembly to prevent movement while in transit.
3. Pack the DECwriter as shown in Figure 2-3.
2.4 EASY IDENTIFICATION OF LOGIC BOARDS
There are three possible logic board models that can be installed in a DECwriter: M7722, M7723, and
M7728. The M7722 board is typically factory installed in earlier LA36s while the M7723 and M7728
boards are found in newer terminals. The M7728 performs all functions of the M7722 and M7723 and
is backward compatible for a direct replacement for either board. Replacing either board with an
M7728 does not enhance the capabilities of the terminal in which the M7728 board is installed.
Figure 2-5 shows the obvious physical differences between the three logic boards that permit easy
identification. The M7722 and M7723 boards each have four connectors while the M7728 has five
connectors. The M7723 and M7728 boards have solder dot test points around the perimeter and the
M7722 does not have these test points.
SOLDER DOTS
TEST POINTS

·• .............. . · ·· ................ ..
•
•
•
•
·
.
·••
•
·•
•

M7722
LOG IC BOARD

•
•

M7723

M772B

LOGIC BOARD

•
•
•
•

.............

••

•
•

..................
5
CONNECTORS

4 CONNECTORS

CP-2391

Figure 2-5

Physical Characteristics of M7722, M7723, and M7728 Logic Boards

2-4

2.S INTERFACE INSTALLATION
1.

Connect one of the following DECwriter interfaces.
NOTE
For additional installation information, refer to the
LA36/LA3S DECwriter II User's Manual, EKLA363S-0P-002.
• Current loop cable (see Table 1-7 for interface specifications); connect per Figure 2-6.
• DEClO current loop cable; connect per Figure 2-7.
• EIA cable (LAXX-KG); connect per Figure 2-8.
• EIA cable (LAXX-LG); connect per Figure 2-8
• Acoustic coupler cable (LAXX-LM); connect per Figure 2-9. For additional acoustic
coupler installation information, refer to LAXX-LM-4 Installation Procedure.
NOTE
Site plans are not supplied by Digital Equipment
Corporation. Interface logic connections must be
specified and provided by the system supplier or the
customer because each installation may be different.

Check and record the options installed in the DECwriter.

2.6 M7722 JUMPER CONFIGURATION
Figure 2-10 shows the location and function of all jumpers on the M7722 logic board.
2.7 M7723 JUMPER CONFIGURATION
Figure 2-11 shows the location and function of all jumpers on the M7723 logic board.
2.8 M7728 JUMPER CONFIGURATION
Figure 2-12 shows the location and function of all jumpers on the M7728 logic board.

2-5

(TO USERS
EQUIPMENT)

PINNING

FROM

Pl-2
Pl-3
Pl-5
Pl-7

P2-3
P2-2
P2-7
P2-5

CP-2043

Figure 2-6

DECwriter Current Loop Cable Connection

2-6

2838 CONNECTOR
~ (TELEPHONE

CONNECTOR)

CP-2042

Figure 2-7

DECwriter DEClO Current Loop Cable Connection

2-7

STANDARD EIA MODEM - TERMINAL INTERFACE CONNECTIONS
SENTTO

NAME

1
2

FG
TO
RD
RTS
SG
DCD
NONE
DTR
RI

3
4
7
8
11
20
22

EIACIRCUIT
DESIGNATION

FUNCTION
FRAME GROUND
TRANSMITTED DATA
RECEIVED DATA
REQUESTTO SEND (NOTE 11
SIGNAL GROUND
DATA CARRIER DETECT (NOTE 2)
UNASSIGNED
DATA TERMINAL READY (NOTE 11
RING INDICATOR (NOTE 2)

AA
BA
BB
CA
AB
CF
NONE
CD
CE

DATA TERMINAL
EQUIPMENT
(DECwriter)

DATA
COMMUNICATIONS
EQUIPMENT

X
X
X
X
X
X

NOTES:
1.
2.
3.
4.

REQUEST TO SEND AND DATA TERMINAL READY ALWAYS ASSERTED ON LAXX-KG.
DATA CARRIER DETECT AND RING INDICATOR NOT USED ON LAXX-KG.
POSITIVE VOLTAGE EQUALS BINARY ZERO. SPACE. ON.
NEGATIVE VOLTAGE EQUALS BINARY ONE. MARK. OFF.

LAXX - KG or LG

TO USERS
EQUIPMENT

~P1

CP-2046

Figure 2-8

DECwriter EIA Logic Board Connection
2-8

CARRIER INDICATOR

TELEPHONE
HANDSET
FOLDED
CABLE

LOGIC BOARD
M7722
M7723
M7728

CP-2190

Figure 2-9

Acoustic Coupler Cable Connection

2-9

W54

M7722 CURRENT LOOP CONFIGURATION JUMPERS
JUMPER

W12

W32

W&4

FULL-DUPLEX ACTIVE

FULL-DUPLEX
PASSIVE

PASSIVE RECEIVE/
ACTIVE TRANSMIT

W2 W5 W3 W32 W9 we W6 W7

W10

W12
(PINS 4 TO 13) W1

ACTIVE RECEIVE/
PASSIVE TRANSMIT

HALF-DUPLEX
ACTIVE"

HALF-DUPLEX
PASSIVE"

~ca7 ~..

~ caa

n
c:::>
y=:>O
=

"CONNECT USER-MANUFACTURED CABLE BETWEEN J3-3 ANC» & AND OPERATING SYSTEM.

f
C>

11 B~Q 8
OQ

LEGEND:
1 = JUMPER INSTALLED.
o = JUMPER NOT INSTALLED.

E67

M7722 PARITY CON~IGURATION JUMPERS
FUNCTION

W10

8TH BIT MARKING
(NO PARITY)

EVEN PARITY

LEGEND:
1 = JUMPER INSTALLED.
o = JUMPER NOT INSTALLED.
M7722 BELL VOLUME
W1 INSTALLED - STANDARD BELL VOLUME
W1 NOT INSTALLED - LOWER BELL VOLUME

o 0 o o 009 0 0~o 0
0~ 09000
o0
o 0 o O~
OQ

c{Ij]

Jo'ill

CP-3142

Figure 2-10 Location of Jumpers
on M7722 Logic Board
2-10

JUMPER CONFIGURATIONS FOR M7723 LOGIC BOARD
FUNCTION

W13

W14

FULL-DUPLEX ACTIVE

FULL-DUPLEX PASSIVE

PASSIVE RECEIVEI
ACTIVE TRANSMIT

ACTIVE RECEIVEI
PASSIVE TRANSMIT

HALF-DUPLEX ACTIVE'

HALF-DUPLEX PASSIVE'

'CONNECT USER-MANUFACTURED CABLE BETWEEN J3-3 AND I AND OPERATING SYSTEM.

FUNCTION
8TH BIT MARKING
8TH BIT SPACING
EVEN PARITY
ODD PARITY

W10

W11

0
0
1
1

X
X
0
1

0
1
X
X

LEGEND
1 = JUMPER INSTALLED
o = JUMPER NOT INSTALLED
X
DO NOT .CARE

W1 INSTALLED
W1 NOT INSTALLED
W12 NOT USED

STANDARD BELL VOLUME
LOWER BELL VOLUME
NO FUNCTION

W16

W11

8142-1

Figure 2-11 Location of Jumpers
on M7723 Logic Board
2-11

JUMPER CONFIGURATIONS FOR M7728 LOGIC BOARD
i

FUNCTION

W15

W13

FULL-DUPLEX ACTIVE

FULL-DUPLEX PASSIVE

PASSIVE RECEIVE/
ACTIVE TRANSMIT

ACTIVE RECEIVE/
PASSIVE TRANSMIT

HALF-DUPLEX ACTIVE·

HALF-DUPLEX PASSIVE·

W14
1

,
1

1
1

1
0

0
0

0
i

·CONNECT USER-MANUFACTURED CABLE BETWEEN J3-3 AND 6 AND OPERATING SYSTEM.

FUNCTION
8TH BIT MARKING
8TH BIT SPACING
EVEN PARITY
ODD PARITY

W10

W11

W115

0
0
1
1

X
X
0
1

X
X

~} NO PARITY
W16

LEGEND:
1
JUMPER INSTALLED.
o = JUMPER NOT INSTALLED.
X = DO NOT CARE.

W18

W19

W20

PRINT PARITY ERROR
INDICATION

EIGHT BIT CONTROL OVER
OPTIONS
(NO PARITY DETECTION)

FUNCTION

W1 INSTALLED

STANDARD BELL VOLUME

W1 NOT INSTALLED

LOWER BELL VOLUME

W121NSERTED

PRINT ALL CHARACTERS TYPED
WHETHER LOCAL OR ON LINE IN FULL
OR HALF DUPLEX

W12 NOT INSTALLED

POSITION OF FDX/HDX SWITCH
ESTABLISHES WHETHER TRANSMITTED CHARACTERS ARE PRINTED

W16 NOT USED

NO FUNCTION

W17 NOT USED

NO FUNCTION

W20

W11

W19

W18

W10

W15
8142-2

Figure 2-12 Location of Jumpers
on M7728 Logic Board
2-12

2.9 LA36 CHECKOUT AND ACCEPTANCE PROCEDURES
Perform the following procedure. If the desired results are not achieved, refer to the troubleshooting
guide in Chapter 6 (Table 6-4).
1.

Install ribbon per ribbon installation procedure (Chapter 3).

Install paper per paper loading procedure (Chapter 3).
CAUTION
Before connecting the LA36 to a power source,
ensure that the line voltage and frequency are compatible with the power requirements of the machine.
Ensure that the POWER switch on the console is
OFF.

Connect the LA36 line cord to the correct wall receptacle; press the control panel POWER
switch to the ON position. The print head automatically positions itself to the left margin.

Set the baud rate to 300 and the LINE/LOC switch to LOC.

Press the LINE FEED key, hold down the CTRL key, and then press the BELL key. The
stepping motor will advance the paper one line and the bell tone will sound. Type a line of
characters. When the print head passes the 64th character position, the bell tone will sound.

Press the BACKSPACE key. The print head will move one character position to the left.

After 132 characters have printed, press the RETURN key and observe the return of the
print head to the "home" position.

Set the BAUD RATE switches to the setting prescribed for the operating system.
NOTE
Both the 110 and 300 BAUD RATE switches must
be depressed to obtain a baud rate of 150.

2.10 LA3S CHECKOUT AND ACCEPTANCE PROCEDURES
Perform the following procedure. If the desired results are not achieved, refer to the troubleshooting
guide in Chapter 6.
1.

Install ribbon per ribbon installation procedure (Chapter 3).

Install paper per paper loading procedure (Chapter 3).
CAUTION
Before connecting the LA3S to a power source,
ensure that the line voltage and frequency are compatible with the power requirements of the machine.
Ensure that the POWER switch on the console is
OFF.

2-13

Connect the LA3S line cord to the correct wall receptacle; press the control panel POWER
switch to the ON position. The print head automatically positions itselfto the left margin.

Set the BAUD RATE switches to the applicable baud rate.

Set the LINE/LOC switch to LINE.

Run the applicable software and observe printout for the desired results.

2-14

CHAPTER 3
OPERATION

3.1

LA36 OPERATOR CONTROLS AND INDICATORS
NOTE
Dot on switch indicates function of switch when
depressed.

7622-28

3.1.1 POWER ON/OFF Switch
The POWER ON/OFF switch connects and disconnects the line voltage to the LA36 OECwriter II.
The POWER switch should be in the ON position for normal unit operation. When changing paper,
ribbon, or adjusting the print head, the switch should be turned OFF.
3.1.2 LINE/LOC Switch
The LlNE/LOC switch is a 2-position operator control switch. When in the LINE position, the LA36
is enabled to transmit and receive data. When in the LOC position, the LA36 receive/transmit lines are
disabled and only local operations can be performed.
3.1.3 FDX/HDX Switch
The FOX/HOX switch controls the printing of transmitted keyboard characters. When in the FOX
position, characters typed on the keyboard are transmitted; only received characters are printed. When
in the HOX position, keyboard characters are both transmitted and printed; received characters are
also printed. The operator should not attempt to transmit data when receiving data in the HOX mode.

3-1

7622-28

3.1.4 BAUD RATE Switches
The BAUD RATE switches select the rate at which characters are transmitted and received over the
communication line.
Switch

Character Rate

110
300
IlOand 300

10 characters/second
30 characters/second
15 characters/second

3.1.5 ALT CHAR SET Switch
When an alternate character set is installed, the ALT CHAR SET switch allows the operator to select
either the standard ASCII character set (switch up) or the alternate character set (switch down).
3.1.6 CHAR SET LOCK Switch
The CHAR SET LOCK switch allows the operator to select manual (switch down) or automatic
(switch up) character set switching. In the automatic mode, the transmitting device can change the
character set by issuing the character codes switch in (control-O) or switch out (control-N). The
switch-in code selects the standard ASCII character set. The switch-out code sClects the alternate
character set. In the manual mode, the character set is selected by the ALT CHAR SET control switch.
3.1.7 STD/ALT CHARACTER SET Indicators
The STD / ALT CHARACTER SET indicators give a visual indication of the selected character set. If
no alternate character set option is installed, the STD indicator will always be illuminated when power
is on.
3.1.8 AUTO LF Switch
The AUTO LF switch is an optional operator c()ntrol that is inoperative unless option LAXX-LA or
LAXX-KX is installed in the LA36. When either option is installed and the AUTO LF switch is
enabled, an LF control code will be transmitted each time a carriage return code is transmitted.
3.1.9 HERE IS Switch
The HERE IS switch is an optional operator control that is inoperative unless option LAXX-KX is
installed in the LA36. When the LAXX-KX is installed, depressing the HERE IS switch will cause a
20-character preprogrammed message to be transmitted.
3.1.10 PAPER OUT Indicator
When illuminated, the PAPER OUT indicator gives a visual indication that the LA36 is out of paper.
Printing stops when the out-of-paper condition is detected.
.
3-2

7622-28

3.1.11 DEVICE SELECT Indicator
The DEVICE SELECT indicator, when illuminated, gives a visual indication that the LA36 has been
selected as a slave terminal and can transmit data back to the transmitting unit. This indicator is only
operative when the Selective Addressing Option LAXX-KW is installed in the LA36.
3.1.12 SELECT AVAIL Indicator
The SELECT A VAIL indicator gives a visual indication that the data communication channel is
available and that the LA36 has the ability to initiate data transmission. This indicator is only operative when the Selective Addressing Option LAXX-KW is installed in the LA36.
3.1.13 CTRL Key
The CTRL key provides the LA36 operator with a method of transmitting ASCII control codes
(0008-0378). Holding the CTRL key down and pressing any alphanumeric key or control key changes
the standard alphanumeric ASCII code for that key to a control code (0008-0378).
3.1.14 CAPS LOCK Key
The 26 letter keys transmit only uppercase when the CAPS LOCK switch is down. None of the other
keys are affected.
3.1.1S SHIFf Key
This is a momentary switch which, when depressed, allows selection of uppercase for all printable
characters.
3.1.16 TAB Key
The printer does not respond to TAB (code 011 8) unless option LAXX-KY is installed.
3.1.17 ESC (SEL) Key
The ESC (SEL) key generates code 033 8. This provides the LA36 operator with a convenient method of
generating an escape command code sequence. The printer does not respond to the escape code unless
option LAXX-KY is installed.
3.1.18 REPEAT Key
The REPEAT key does not generate an ASCII code. However, when the REPEAT key is held down
and any key is depressed, it causes the ASCII code for that character to be transmitted and printed at a
repetition rate of approximately 15 characters/second (until the key is released).
3-3

7622·28

3.1.19 RETURN Key
The RETURN key generates code 015 s. The printer control logic causes the print head to be repositioned to the left-hand margin each time the carriage return character code is received. If a line feed
(LF) character code follows the carriage return code, the line feed operation is executed simultaneously
with the carriage return. With options LAXX-LA or LAXX-KX installed, the capability of adding a
line feed command after the carriage return is included.
3.1.20 LINE FEED Key
The LINE FEED key generates code 012 s. The printer will advance the paper one line each time the
LF code is received.
NOTE
Rapid paper advance can be obtained by placing the
LA36 in the local mode and pressing the LINE
FEED and REPEAT keys.
3.1.21 BACKSPACE Key
The BACKSPACE key generates code 01Os. The printer control logic causes the print head to move
one position to the left each time a BACKSPACE code is received, until the print head reaches the lefthand margin.
3.1.22 DELETE Key
The DELETE key generates code 177s. The printer does not respond to the delete code.
3.1.23 BREAK Key
The BREAK key is provided for users that utilize the half-duplex mode of transmission. The BREAK
key allows the LA36 operator to interrupt incoming data flow by forcing the communication line from
a mark mode into the space mode (until the BREAK key is released). If the LAXX-LG EIA interface
is installed, a short space (230 ms) will be generated.

3-4

3.1.24 Numeric Keypad
The numeric keypad enables numbers to be
entered in an adding machine fashion. Each key
in the numeric keypad generates the same ASCII
character as the corresponding key in the main
keyboard. The ENTER key corresponds to the
RETURN key.

7622-9

,3.1.25 Bell
The bell indicates that a bell code was received, or that the print head has reached column 64.

3-5

3.2 LA35 OPERATOR CONTROLS AND INDICATORS
NOTE
Dot on switch indicates function of switch .when
depressed.

7666-22

3.2.1 LINE/LOC Switch
The LINE/LOC switch is a 2-position operator control switch. When in the LINE position, the LA35
is enabled to receive data. When in the local mode, the LA35 receive line is disabled and only local
operations can be performed.
3.2.2 BAUD RATE Switches
The BAUD RATE switches select the rate at which characters are received over the communication
line.
Switch

Character Rate

110

10 characters/second
30 characters/second
15 characters/second

300
110 and 300

3.2.3 PAPER OUT Indicator
The PAPER OUT indicator, when illuminated, gives a visual indication that the LA35 is out of paper.
Printing stops when the out-of-paper condition is detected.
3.2.4 POWER ON/OFF Switch
The POWER switch connects and disconnects the line voltage to the LA35 DECwriter. The POWER
switch should be in the ON position for normal unit operation. When changing paper, ribbon, or
adjusting the print head, the switch should be turned OFF.
3.2.5 HEAD OF FORM Switch
This switch is operational only when the Top of Form Option is installed. Its function is to advance the
paper to the head of the form.
3.2.6 Bell
The bell indicates that a bell code was received.

3-6

3.3 LA36jLA35 COMMON CONTROLS
3.3.1 Carriage Adjustment Lever
The Carriage Adjustment lever controls the
print head gap for single-part or multipart
forms.

..... n'I<,.... E
ADJUSTMENT
LEVER

766&16

3.3.2 Paper Advance Knob
The Paper Advance knob pushes in to disengage
the line feed gear train, allowing fine vertical
adjustment of paper position. Coarse vertical
adjustment is achieved by simply turning the
knob. Each detent turned represents one line.
PUSH IN HERE
AND TURN TO
ADJUST PAPER - - VERTICALLY

PAPER
ADVANCE
KNOB

7595-4

3-7

3.3.3 Tractor Adjust Knob
The Tractor Adjust knob allows fine horizontal
adjustm,ent of forms.

7595-7

3.3.4 Cover Interlock Switch
The cover interlock switch prevents the LA36 from operating when the cover is open. When the cover
is opened, the PAPER OUT indicator will light and the keyboard will become inactive. The
LINE/LOC switch or the POWER ON/OFF switch can be used to reactivate the LA36.

3-8

3.4 LOADING PAPER AND NEW FORMS
The LA36/LA35 can accept multipart forms, with widths from 7.62 to 37.8 cm (3 to 14-718 inches).
When loading new forms, it is necessary to perform two adjustments:
1.
2.

Paper Positioning (Paragraph 3.4.1)
Impression Adjustment (Paragraph 3.4.2).

In addition, there is a horizontal positioning (Paragraph 3.4.3) and vertical positioning adjustment
(Paragraph 3.4.4). The horizontal positioning adjustment allows the paper to be slightly shifted left or
right. This procedure is especially useful when typing on preprinted forms with defined horizontal
zones. The vertical positioning adjustment enables the paper to be adjusted vertically. Once these
adjustments have been performed, reloading paper (Paragraph 3.4.5) becomes quick and simple,
requiring a minimum of interruption.

3.4.1

Paper Positioning Procedure

1. Set the POWER switch to OFF.

2. Lift the cover.
3. Place the tractor-feed paper on the floor
between the legs of the LA36/LA35. (The
term tractor-feed refers to the holes on
either side of the paper.)
NOTE
Ensure that the leading edge of the forms is
directly below and parallel to the feed slot.

7666-14

3-9

4. Open the left tractor cover so that the tractor pins are exposed.

7666-32

5. Move the Carriage Adjustment lever to the
highest number (toward operator).

ADJUSTMENT
LEVER

3-10

7666-16

6. Feed the paper through the load channel
under the terminal and align the left paper
margin holes over the left tractor pins.
7. Close the left tractor cover.

8. Loosen the Tractor Adjustment knob on
the right tractor about 1/2 turn.
9. Open the right tractor cover and slide the
tractor to a position where the holes on the
right paper margin align directly over the
tractor pins.
10. Close the tractor cover.

NOTE
Ensure that the paper does not pull against
the tractor pins or bow in the middle.
11. Tighten the tractor adjustment. and proceed to the impression adjustment (Paragraph 3.4.2).

7668-35

3-11

3.4.2

Impression Adjustment

NOTE
The Carriage Adjustment lever is normally set forward (to notch number 1) for single-thickness
paper. The following procedure is applicable only
to multipart forms.

Set the POWER switch to OFF.

Set the Carriage Adjustment lever to the
number corresponding to the number of
parts in the form.

Turn the Paper Advance knob counterclockwise while moving the Carriage
Adjustment lever forward one notch at a
time until the paper smudges; then move
the lever back one notch at a time until the
paper no longer smudges.

Set the POWER switch to ON and resume
operation.
NOTE
If the impression is unsatisfactory due to a
worn ribbon, perform the ribbon installation
procedure (Paragraph 3.S). An indication of
a worn ribbon is that the first copy in a multipart copy is poor but the remaining copies
are good.

3-12

3.4.3 Horizontal Positioning Adjustment
The horizontal positioning adjustment enables
the paper to be shifted left or right [1.27 cm (1/2
inch), maximum]. Shifting the paper provides a
simple means of aligning the type within the
appropriate columns on the paper.

Set the POWER switch to OFF.

Lift the cover and loosen both Tractor
Adjustment knobs about 1/2 turn.

Move the tractors the desired amount [1.27
cm (1/2 inch), maximum] to have characters type in the appropriate columns.

TRACTOR ADJUSTMENT KNOBS

7666·10

Tighten the Tractor Adjustment knobs.
NOTE
Ensure that the paper does not pull against
the tractor pins or bow in the middle.

3.4.4 Fine Vertical Positioning
F or fine vertical positioning, press in and turn
the Paper Advance knob.

PUSH INHERE
AND TURN TO
ADJUST PAPER - - VERTICALLY

PAPER
ADVANCE

KNOB

759&-4

3-13

3.4.S Reloading Paper
1.

Set the POWER switch to OFF.

Lift the cover.

Place the tractor-feed paper on the floor
between the legs of the LA36/LA35.

Open both tractor covers so that the tractor
pins are exposed.
NOTE
Ensure that the leading edge of the forms is
directly below and parallel to the feed slot.

Feed the paper through the load channel
under the terminal and align the paper
holes over the tractor pins.

Close the tractor covers.

3-14

3.5 RIBBON INSTALLATION
The printer ribbon should last for 16 to 20 hours of actual printing at 30 characters/second (about 2
million characters). After 12 hours, or when the print density becomes too light, remove both ribbon
spools from their drive spindles and turn the whole assembly over so that the previous lower edge of
the ribbon is now on top. After rethreading the ribbon, another 8 hours (approximately) of printing
time is possible before the ink is completely used. At that time, the ribbon must be replaced by removing both spools and un threading the ribbon. Replace with a new spool and ribbon assembly (Part No.
36-10558) and an empty spool. (One of the old spools may be used if desired.)
NOTE
Use only DIGITAL-recommended ribbons (Part No.
36-10558). Use of other ribbons can cause damage
and void machine warranty.

I. Set the POWER switch to OFF and lift the
cover.
2. Record the setting of the Carriage Adjustment lever. Move the Carriage Adjustment
lever to the highest number.
3. Remove the ribbon spools and ribbon.
Save one spool to be used with the new
ribbon.

7666-32

3-15

4. Connect the hook on the end of the ribbon
to the empty spool.

7666·17

5. Wind 10 turns of ribbon on the empty
spool.

7666·21

7622-22

3-16

® CD

CARRIAGE LEVER ADJUSTMENT

ET
CP-2006

6. Place the full spool on the left spindle and turn clockwise until it drops into position.
7. Guide the ribbon around idler spool A through guide B, and around the outside of idler spools C
through E.
8. Guide around the front of head F and idler spools G through I.
9. Guide the ribbon through slot J (direction changing guide) and around idler spool K.
10. Turn the spool clockwise until it drops into position.
II. Take up the slack in the ribbon by turning the free moving spool.
12. Return the Carriage Adjustment lever to its original setting.
NOTE
The rivet located on the ribbon must be on the spool
or between the spool and the direction changing
guide.

Ribbon can be threaded in the opposite direction
(from K to A).

3-17

3.6 DECwriter INTERFACE
INFORMATION
3.6.1

f - - - - - 100ms-----I-1

1 -.
I1
.

Interface Description

,
I

NOTE
'The LA35 and LA36 have identical interfaces.
However, the LA35 utilizes only the receive
circuitry.

11
START
BIT

I
I

40V

Voltage drop, marking
Spacing current
Marking current

0.5 V
2.0V
O.4mA 2.0mA
20mA 80mA

I
I

,
I

I
I

....I1L.......i1'--l''--I'---L...L.J

I
I

I
I I
START
BIT

8
PARITY
DATA MSB
BITS

LSB

1 I
STOP
BIT

150 BAUD

rA-.

--·IL.....L.[--'-:_TL.......iT'--IT'--IT'--IT_~...L:_1...J!
•

-I I- 6.66ms

1,. . .- - - 33.3 ms ---.-1
I
I
I
I
I

Max.

5.0V

110 BAUD

-I 1-9.09ms
I..
6 6 . 6 m s - - -....
·1
,
,

Passive, isolated, goes to mark state when power
is turned off.

Open circuit voltage
(of circuit being driven)

2
STOP
BITS

,"~-"-I-"-,--'-I

Transmitter (LA36 only)

Min.

8
DATA
BITS

1~[1T~~~T~~~~~~;t,;t~~I~i~---

There are three interface option kits available
for the DECwriters: LAXX-LH, 20 mA Cable
Option Kit; LAXX-LK, 20 mA Cable Option
Kit (DEClO); LAXX-LG, EIA Interface Option
Kit. Refer to Chapter 2 of this manual for installation instructions for these interfaces.
3.6.2 Interface Specifications
The interface specifications for the DECwriter
serial 20 mA current loop are shown below.

LSB

, 1

8
DATA
BITS

START~LSB
BIT _

PARITY

,..-.....

1 I

MSB~
~ STOP
_ _ BIT

300 BAUD

,,..-....

..I TI-rl-'---I
I
I
I
I
I
I
[ ~~..,..TI
I
I
I
I
I
I
I
I
,

...J

-I I- 3.33ms
CP-1177

Serial Interface Timing Diagram

Receiver
Passive, isolated
Min.
Voltage drop, marking
Spacing current
Marking current

Max.
Receiver/Transmitter (LA36 only)

1.2 V
2.7 V
O.OmA 3.0mA
15mA 80mA

Active, half-duplex
Min.

Cable
Voltage drop, marking
Spacing current
Marking current

4-conductor LAXX-LH or LAXX-LK
[Cable extension up to 492 m (1500 ft) is
permitted]

3-18

Max.

1.7V
4.7V
O.OmA 3.0mA
15mA 80mA

3.7 PROGRAMMER'S GUIDE
3.7.1

,.-------------,

LA36 Programmer's Information

I II

NOTE
All information in this paragraph is applicable to
the LA3S, with the exception of keyboard operations (Paragraph 3.7.3). This is due to the fact
that the LA36 and LA3S receive operations and
baud rates are identical.

BUFFER

I:
I

RECEIVER

INCOMING
DATA

L ____________ J

r------------,
I
I

KEYBOARD

OUTGOING
DATA

IL _ _ _ _ _ _ _ _ _ _ _ .JI

3.7.2 Transmitting Characters and Commands
The only wayan operator can transmit data is
by typing keys on the keyboard. The 7-bit ASCII
equivalent of each key is transmitted the instant
a key is depressed.

LA36
CP-llIS8

3.7.3 Special Command Keys
3.7.3.1 CfRL Key - Holding down the CTRL key changes the ASCII code transmitted when another
key is typed in that it forces bits 6 and 7 to O. For example, the ASCII code for the letter "g" is 147
( 00111).
Bits 6 and 7
Holding down the CTRL key and typing the "G" key transmit the ASCII code 007

The CTRL key enables the LA36 operator to transmit all ASCII control codes (000-037).
3.7.3.2 BREAK Key - The BREAK key is commonly used to manually interrupt the flow of data
coming to the LA36. The function of the BREAK key is to cause the transmitted data signal from the
LA36 to go to the space condition while the BREAK key is depressed. If the LAXX-LG EIA/CCITT
interface is installed, then the BREAK signal is limited to approximately 230 ms.
3.7.4 Receiving Characters and Commands
The DECwriter receives commands as well as characters to be printed in the form of 7-bit ASCII
codes.
Normally, the DECwriter prints characters and processes commands as fast as they are received. The
one exception is the return operation (moving the print head back to the left margin). Return can take
longer than the time interval between two successive data inputs. This is a normal condition for
mechanical devices, which are slower than electronic signals. The normal programming practice is to
compensate for this time lag by using filler characters (such as ASCII 000) to take up slack time.
In the LA35 and LA36, it is necessary that a single non printing, nonspacing character be sent after a
carriage return or that carriage return is followed by 33.33 ms of idle (marking) line time.
The nonprinting, nonspacing character requirement is fulfilled by the line feed, (LF) code which normally will follow CR. The LF function will be executed simultaneously with CR.
Additional CR characters sent without an intervening character that causes printing or spacing will be
disregarded.
Table 3-1 lists the 7-bit ASCII codes used by the DECwriter and indicates the operations performed by
the printer. Note that some ASCII codes, though generated by the keyboard, are not recognized by the
printer.

3-19

Table 3-1 ASCII Codes and Responses
RECEIVE OPERA nONS

KEYBOARD OPERAnONS
To Transmit, Type Key(s) (LA36)
ASCII Code

Character

000
001
002
003

NUL
SOH
STX
ETX
EOT
ENQ

004

005
006
007
010
011
012
013
014
015
016
017
020
021
022
023
024
025
026

SHIFT*

CTRL*

..;

ACK
BEL

..;
..;
..;
..;
..;
..;
..;
..;

HT
LF
VT
FF
CR
SO
SI
DLE
DCl
DC2
DC3
DC4
NAK
SYN
ETB

027
030
031

CAN

032

SUB

033

ESC

034
035

037

GS
RS
US

040

036

..;
..;

..;
..;
..;
..;
..;
..;
..;
..;
..;
..;
..;
..;
..;
..;
..;
..;
..;
..;
..;
..;
..;
..;
..;

CHAR

Character
Printed

Action/Description

SPACE

None

A
B
C
D
E

None
Sound Alarm Bell

BELL

Backspace one position

H
I

None
Advance Paper one line
None
None
Move print head to left margin
None

J
VT
FF
M
N

0
P
Q
R
S
T
U
V
W
X
Y

Z
[

=
'"

space bar

.,
None
Blank Spacd

None
Print character, move print head
one position to the right.

*A check in this column indicates the key (SHIFT or CTRL) that must be held down while the character key is typed.
If both keys are checked, then both keys must be held down.

3-20

Table 3-1 ASCII Codes and Responses (Cont)
RECEIVE OPERATIONS

KEYBOARD OPERATIONS
To Transmit, Type Key(s) (LA36)
ASCII Code

Character

SHIFf*

041
042
043

!
"

044

045
046
047
050
051
052
053
054
055
056
057
060
061
062
063
064
065
066
067
070
071
072
073
074
075
076
077
100
101
102
103
104

%
&

v'
v'
v'
v'
v'
v'

(
)

*
+

v'
v'
v'
v'

CTRL*

CHAR

Character
Printed

Action/Description

!
"

Print character, move print head
one position to the right.

%
&

(

(
)

)

0
1
2
3
4
5
6
7

8
9

<
=
>

v'
,

<
=
>
?
@

v'
v'
v'
v'

v'
v'
v'

C
0

A
B

Print character, move print head
one position to the right.

*A check in this column indicates the key (SHIFT or CTRL) that must be held down while the character key is typed.
If both keys are checked, then both keys must be held down.

3-21

Table 3-1 ASCII Codes and Responses (Cont)
RECEIVE OPERAnONS

KEYBOARD OPERAnONS
To Transmit, Type Key(s) (LA36)
ASCII Code

Character

SHIFT··

105
106
107
110

E
F

..j

..j
..j
..j
..j
..j

III
112
113
114
115
116
117
120
121
122
123
124
125
126
127
130
131
132
133
134
135
136
137
140
141
142
143
144
145
146
147
150

H
I
J
K
L
M
N

0
P

Q
R

T
U
V
W

X
Y
Z
[

V
..j
..j
..j
..j
..j
..j
..j
..j
..j
..j

CTRL·

CHAR

Character
Printed

E
F

H
I
J
K
L
M
N

R
S

U
V

U
V
W

..j
..j
..j

X
Y
Z
[

X
y

\
..j

]

\
]

I\.

a
b
c
d
e
f

E
F

a
b
c
d
e
f

B
C

Print character, move print head
one position to the right.

Z
[

]

Action/Description

...
Print character, move print head
one position to the right.

*A check in this column indicates the key (SHIFT or CTRL) that must be held down while the character key is typed.
If both keys are checked, then both keys must be held down.

3-22

Table 3-1

ASCII Codes and Responses (Cont)
RECEIVE OPERATIONS

KEYBOARD OPERATIONS
To Transmit, Type Key(s) (LA36)

Character
CHAR

Printed

i
j
k
1

I
J
K

i
j
k

m
n

M
N
0
P

m
n

ASCII Code

Character

151
152
153
154
155
156
157
160
161
162
163
164
165
166
167
170
171
172
173
174
175
176
177

DEL

SHIFT*

CTRL*

P
q

r
s

t
u
v

s
t
u
v

U
V
W

Y
Z

I
I

..;
..;
..;

Print character, move print head
one position to the right.

P
q

Action/Description

DELETE

None

Print character, move print head
one position to the right.
None

• A check in this column indicates the key (SHIFT or CTRL) that must be held down while the character key is typed.
If both keys are checked, then both keys must be held down.

3.8 USING THE LA36
The following steps are all that may be required to place your LA36 on-line.
1.
2.
3.
4.

5.
6.
7.
8.

Load paper (described in Paragraph 3.4).
Set LINE/LaC switch to LaC.
Set POWER switch to ON.
Select full-duplex or half-duplex mode (FDX/HDX switch).
Select character set (ALT CHAR SET and CHAR SET LOCK switches), if applicable.
Select AUTO LF, if applicable.
Select desired baud rate (BAUD RATE switches).
Set the LINE/LaC switch to LINE.

The LA36 is now on-line and ready to receive and transmit data.
3-23

3.9 USING THE LA35
Using the LA35 requires almost no operator intervention. The following steps are all that may be
required to place the LA35 on-line.

I.
2.
3.
4.

Load paper.
Set the LINE/LOC switch to LINE.
Set the BAUD RATE switches to the appliable baud rate.
Set the POWER switch to ON.

The LA35 is now on-line and fully operational.
3.10 TROUBLESHOOTING
Operator-related troubleshooting information is listed in Table 3-2.

Table 3-2
Symptom
DECwriter does not turn on
when POWER switch is set to
ON.

Operator's Troubleshooting Guide
Possible Cause and Corrective Action
• AC power cord is not plugged into wall outlet - plug it in.
• Current is not coming from wall outlet - check outlet with a
known working electrical device (such as a lamp).
• Check ac line fuse (following page).
• If none of the above, contact your local Field Service Office.

Print head does not print
characters.

• Check servo fuse - might be blown (following page).
• Print head may be set too far from paper - adjust the Carriage Adjustment lever.
• Check option interconnect cable (Chapter 2).

Light print

• Print head may be set too far from paper - adjust the Carriage Adjustment lever per impression adjustment procedure
(Paragraph 3.4.2).
• Ribbon ink has run out - replace ribbon.
• Reverse ribbon after 8-12 hours of continuous printing. Ribbon should be reversed only once, then changed.

Paper does not advance

• Improper loading of paper - check tractor covers to ensure
that they are closed.
• Holes in paper are torn - turn DECwriter OFF and reload
paper properly.
• Paper snagged or caught by box.

3-24

Table 3-2
Symptom

Paper tearing on multipart forms

Operator's Troubleshooting Guide (Cont)
Possible Cause and Corrective Action

• Print head is exerting pressure on paper so that paper tears
when it advances - check print head position control (adjust
Carriage Adjustment lever).
• Tension exerted on the paper by the tractors is incorrect.

Line bunching

• Tension exerted on the paper by the tractors is excessive.

FUSE RATING
115 V. 3A S8
230V. 1.5A S8
7622-21

LA36/LA35 Fuse Locations

3-25

CHAPTER 4
THEORY

This chapter contains microprogram information timing, detailed control logic theory, and mechanical theory for the DECwriter II. The program description is divided into two parts. The first part
(Paragraph 4.1) is a general description supported by a flow diagram. The second part (Paragraphs
4.1.1 through 4.1.11) is a series of detailed descriptions of the routines supported by detailed flow
diagrams. A detailed description of the scratch pad memory is presented before the routine
descriptions.
The control logic theory is also divided into two parts. The first part (Paragraph 4.3) is a functional
system description supported by a block diagram. The second part (Paragraphs 4.4 through 4.13) is a
series of detailed descriptions of the functional systems supported by block diagrams and detailed logic
diagrams. Mechanical theory of operation is presented in Paragraph 4.14. The mechanical descriptions
are supported by simplified diagrams. The logic functions and signal names that are used in these
diagrams and descriptions are cross referenced to improve usability.
For example, DECI (Decoder 1) is a logic function that appears on a block diagram. The location of
this function in both the simplified and detailed logic diagrams is identified by the notation, MPC4
(microprogrammed controller, page 4). Signal names, SET HDE for example, are cross referenced in
the same manner, using the signal source for reference. Thus, cross reference is as follows.
SETHDE

DECI

. unctIOn
IOglC

signal name

Signal abbreviations are explained in Appendix C, Table C-2. This table also lists signal source and
destination information. A complete set of logic diagrams is provided in Chapter 10.

4.1 PROGRAM DESCRIPTION
The microprogram consists of several instruction sequences connected by major decision nodes as
shown in Figure 4-1.
The first sequence is the initialize (INIT) routine. This routine initializes all the control RAM locations
and moves the print head to the left margin. The next sequence is the position (POSIT) routine.
Requests for print head position changes (such as for print or carriage return) are processed. All
position information is in units of character cells and is stored in locations of the control RAM
(random access memory). In addition, indications of print head position change are processed.
(CARRY is equal to one column forward.) The SERVO routine interacts with the POSIT and SPEED
routines to correct position error. In the SPEED routine, a speed is commanded to the carriage servo
system based on the difference between actual and desired print head positions. Possible speeds
include7.62 cm/sec (3 in/sec) for normal printing, 15.24 em/sec (6 in/sec) for catch-up mode, 127
em/sec (50 in/sec) for carriage return, slower speeds for carriage return slowdown, and 0 in/sec for
idle.
4-1

OVERALL FLOW

AR-ooeJO. POWER UP

ENTERS
AFTER
208CLK
SYNC

PRINT EXIT
,WHILESVNC
ON INC.

,.0

CP·1379

Figure 4-1

Microprogram Flow Diagram

4-2

The INPUT routine operates the character buffer address register as a first-injfirst-out (FIFO) memory. It uses three locations of the control RAM as read address, write address, and word count.
The BELL routine activates the bell system and times the duration of the audible tone bursts.
The PRINT routine requests print head motion and activates the print head solenoids to form the 7 X
7 dot matrix characters. The LINE FEED routine times the four steps and the settling time for the line
feed stepper sytem.
The last character visibility (LCV) routine is entered when no character is being processed. It times the
head step-over delay and requests print head motion.
The NEXT routine is the mate to the INPUT routine. It processes characters out ofthe FIFO memory
and sets up the conditions in the control RAM which will cause their execution.

If the character to be processed is printable, the PRINT routine is activated. If necessary, a recovery
from the LCV position is requested. If the column is 64 and the keyboard has been active on this line,
the end-of-line warning is sounded.
If the character is carriage return, the desired print head position change is entered in the control
RAM. The POSIT and SPEED routines complete the execution of carriage return. Backspace is processed in a similar manner.
If the character is line feed, then the line feed step timing sequence is initiated.
If a bell character is received, the BELL routine is notified. Up to eight sequential bell characters can
be processed and will sound as separate tone bursts.
All other characters cause no action. If 132 characters have been printed on the current line, normally
printable characters also cause no action. Thus, overprinting does not occur.

4-3

4.1.1 Scratch Pad Memory
The variables that are monitored by the microprogram are stored in the control RAM (random access
memory), which is used as a scratch pad memory. Memory locations are utilized as listed in Table 4-1.
The control RAM provides space for 16 words to keep track of various operational conditions within
the LA36 during its operating cycle. Each memory location in this control RAM is 4 bits wide. Some
locations are dedicated exclusively to a specific function and other locations are shared. The dedicated
locations are used for those functions that need to be monitored at all times. The shared locations are
used for variables that are applicable only during certain times in the operating cycle of the machine;
e.g., at one portion of the sequence it is important to keep track of position error but in other portions
it is important to time a line feed, print, or initialize function. However, because these functions are
mutually exclusive in time, they can share the same set of bit positions in the control RAM. Note that
these various functions do not use exclusive bits in a particular location but rather use all four bits of
that location at different times. An exception is location 12 in which the variable PRINT is continuously stored in the least significant bit (LSB) position of that word while timers for LCV, LINE
FEED, PRINT, and INIT are alternately stored in the upper three bits. When timing, these bits are
incremented each time by 2 instead of I to preserve the proper state of the LSB which is (I) for PRINT
and (0) for LINE FEED.
Locations 0, I, and 2 of the control RAM are used to monitor carriage position within each printable
line and are, at all times, an indication of where the head (or carriage) is actually located. Locations 3
and 4 provide a total of 8 bits that indicate the column in which the last character was printed (or, in a
sense, where the carriage should be located.
Positions 5, 6, and 7 are used to control the operation of the character buffer (FIFO). These are read
address, write address, and word (character) count. When the word count (WD CNT) is equal to 0
(buffer empty), it does not matter what the read or the write addresses are if they are equal to each
other. This ensures that upon receipt of the next character, these addresses will continue to track each
other.
The read and write addresses in positions 5 and 6 share those positions with one of the LCV timers for
timing out the 1.3 second head step-over function for LCV. This is feasible because LCV will occur
only when WD CNT is equal to 0; while the read and write addresses are equal, these positions are
available for timing that function. Upon receipt of the next character from the UART, the write
address and WD CNT are incremented. When that character is read out of the buffer, the read address
is incremented, creating an equal condition again between locations 5 and 6.
Location 11 is used in combination with location 12 as a counting location for either the dot print or
line feed functions. As previously stated, the LSB of location 12 is set during dot printing and cleared
during line feeding. These states are maintained by incrementing the timer bits in location 12 by 2 each
time instead of by 1. When the count in location II is zero, the printer is neither printing nor line
feeding and location 12 can be used as an LCV timer. Location 12 is also used as a timer during
initialize.

4-4

Table 4-1

Scratch Pad Allocations

Octal Location

Mnemonic

pas La

1
2

POSMD
pas HI

COLLa

COL HI

RDADR
LCV 1

Character Buffer Read Address
LCVTimer

WTADR
LCV 1

Character Buffer Write Address
To Keep WT ADR=RD ADR

WDCNT

Character Buffer Character Count

Usage
12-Bit Carriage Position
(Relative to column)

8-Bit Column Count
(Records columns printed)

Unused

COUNT

Print Dot Count, LF Pulse Count

PRINT
LCV2
LF I
PTI
IN IT 1

LSB= 1 for Print
LCVTimer
Line Feed Timer
Print Timer
Init Timer

POSER
LF 2
PT2
INIT 2

Position Error
Line Feed Timer
Print Timer
Init Timer

LCVST
LCV3

LCV Status
LCVTimer

BELL 1

Bell Timer

BELL 2

Bell Timer

BELLST

Bell Count (Status)

4-5

Location 13 is used as a position error count for use by those routines that alter the position of the
carriage by anything less than 8 columns in either direction. These routines are PRINT, which alters
the position by 1 to print the next character and LCV, which changes the position by +4 on an
interruption of printing and by -4 on a resumption of printing.
Backspace, which is not represented on such in a scratch pad location, is implemented by manipulation
of position error in location 13. When that location is decremented by I, the position count in locations 0, I, and 2 are used in the SPEED routine to command the head to move back one column.
Location 14 contains LCV status and LCV timer information. Although LCV status is required only
when WD CNT = 0, it must be preloaded to a value (128), which when counted up to zero, will
consume 1.3 seconds (the time delay required before the head is moved to the right four columns for
LCV). This preloaded value becomes the most significant part of the LCV timer.
Locations 15, 16, and 17 are used to control the bell. To sound the bell, a 2.4 kHz clock from the logic
is gated to the loudspeaker with a flip-flop that is, in turn, controlled by the microprogram. In this
way, the microprogram determines both the length of the bell tone and time between bell tones.
Bell tone ON/OFF time is set at 106 ms. This is timed in locations 15 and 16. Location 17 is a bell
count or status position, allowing up to 8 bell tones to be executed continuously. By using this scheme,
successive bell codes can be sensed and accumulated at a rate of 30 per second without the necessity of
intervening fill characters, and then applied to the speaker at a rate of about 5 tones per second. A
graphic demonstration of this is seen when it is realized that the 9th bell code would be received before
the first bell tone had ceased.
4~1.2

Initialize (lNIT) Routine

The DECwriter power-up circuit holds the address register (AR) at zero and inhibits the system clock
until dc power is up (within 300 to 700 ms). At the end of this period, the AR is left at zero and the first
instruction is executed. This instruction tests the INIT and if set, causes the program to enter the INIT
routine (Figure 4-2).
This routine clears all flags, clears the control RAM, clears the function enable latches, and sets a low
negative velocity for the carriage. When the carriage finds the left travel limit, the left-hand margin
position is set to zero, INIT is cleared, and the program progresses to the POSIT routine. This routine
is never reentered except in the event of a power-down.

4-6

INIT
CLR BELL
SET LF HOLD
SPEED - -6 IPS
CLR INC

-1
TIME OUT
ROUTINE

-1

COL LO:-O
COL HI:-O
RDADR: -0;
WTADR: -0
WDCNT: -0
CNT: -0;
LCVST: -0
BEL2: -0;
BELST: -0

POSHI: --1
POSMD: --1
POSLO: --5

1 PASS EVERY
416,.s

(POS--5)

CLR KBH
LOAD INC
CNTR/CLR
IN IT

CP-1624

Figure 4-2 INIT Routine
4-7

4.1.3 Position (POSIT) Routine
The POSIT routine (Figure 4-3) is very closely interrelated with the SPEED routine. As described in
the discussion of the scratch pad allocations, the first three locations are a constant indication of actual
carriage position, and the next two locations are a constant indication of the desired carriage position.
Every time the carriage is moved for any purpose, the first three locations are changed accordingly,
and every time the printer is caused to print a character, the next two locations are modified. When
these two counts are equal, no carriage motion occurs, but when they are unequal, a position error is
generated and an appropriate SPEED command is issued to constantly keep these two sets of locations
equal to each other. Because of this, some motion of the printer can be caused by the program simply
by altering these variables in the control RAM location dedicated to that particular monitoring
function.
The operations that alter these position variables as a result of carriage motion are carriage return
(CR), LCV, and print. The function that causes carriage motion as a result of altering the variables is
backspace. Line feed and bell do not affect the position of the carriage.
When a CR is received and processed, the program sets the column count to zero, thereby causing the
SPEED routine to issue a suitable negative SPEED command that causes the carriage to return to the
zero column position.
In LCV, if a timeout has completed following receipt of the last character, -4 is put in position error,
while true column position is preserved, thereby causing the SPEED routine to command the head to
move four columns to the right. In BACKSPACE, however, one is subtracted from the true column
position so that the validity of the column variable is preserved.
The POSIT routine, on the 208 IJ.S clock, checks bell status and, if zero, clears the bell and checks
PRINT. If PRINT is not zero, it checks the print bit and if it is a one, indicating no LF in progress, sets
LF HOLD and proceeds. If LF is indicated by the print bit being 0, the count is checked to see if it has
completed that line feed, and if it has not (non-zero count) it proceeds to the SERVO routine to
continue that operation. If count is zero, then the line feed is complete and it sets LF HOLD before
proceeding with the POSIT routine.
At this point the program checks the position error variable and, if it is zero, proceeds to the SERVO
routine. If an error exists (non-zero), it checks the degree of error and its direction (positive or negative) on a triple-precision basis, and corrects the error by incrementing or decrementing the position
variable until no carries or borrows are sensed.
This is the only time that any SPEED commands are issued to the carriage servo system. All SPEED
commands are a function of POSIT, WD CNT, and PRINT as determined in the SPEED algorithm;
arid all processing of carriage position is done by the POSIT routine, whether the printer is doing a
carriage return, printing, or just correcting position randomly.

4-8

POSIT

CFORPOSITI

POS: -POS+1
'FLOW THROUGH
HERE GENERALLY
EVERY 416 liS.
-1

-1

LINE FEEO
IN PROCESS

LINE FEED NOT
IN PROCESS

CP·1625

CP-,626

POSIT Routine

b. START Routine for Position

Figure 4-3 POSIT and START Routines
4-9

4.1.4 SERVO Routine
The SERVO routine (Figure 4-4) interacts with
the POSIT and SPEED routines. In this routine,
the carries and borrows that are generated as the
head moves through character cell boundaries
are checked and cleared until the position error
is corrected. Each time a carry or borrow is
sensed, it is cleared and the program returns to
the appropriate node in the POSIT routine.
Finally, when no carries or borrows are
sensed,the program proceeds to the SPEED
routine.

-[!IGURE 4-3

--£:IGURE 4-3

CP·1627

4.1.5 SPEED Routine
The SPEED routine (Figure 4-5) checks the
position variable in the first three locations in
the control RAM on a triple-precision basis, and
considers word count in location 7, the print dot
count in location 10, and the state of the print
bit. The SPEED algorithm is represented statistically in Table 4-2.

Figure 4-4

SERVO Routine

Table 4-2

SPEED Algorithm

Count=O WD
PrintinR CNT

Speed (in/sec)
+zPrint
Position -z Retum Motion
~16
~8
~4
~2

The first pass through the program is implemented for situations in which either the returning carriage has overshot its mark or the carriage
has been accidentally moved left while the printer was static in an LCV state. The program
checks position relative to column count and
finds it less than zero. At this point, the program
checks WD CNT and if it finds it zero (no characters to be processed), it causes the SPEED
routine to command a speed of +3 in/sec (+
speed = print motion; - speed = return motion).
If there are characters to be processed (WD
CNT not equal to 0), it commands a speed of +6
in/sec to clear the buffer, providing ample time
to be ready to print the next character.

=0
=1
=1

4-10

=0
=1
=0
=1

=1
... 0
=0
=0
<0
<0

-50

-30
-20
-10
-6

0
+3
+6
+3
+6

(POS LD-POS MOPOS HI VERSIONI
(ACruAL IMPLE·
MENTATIONI

CP-1628

Figure 4-5

SPEED Routine

4-11

If, in checking the high order position bits for zero, the program finds them not equal to 0, the actual
carriage position is indicated to be positive (to the right) and greater than 16 columns from where it
should be. This results in the maximum SPEED command of -50 in/sec being issued.
As the carriage begins to move in response to this command, the program loops through its sequence
checking the middle four, and then the low four bits of POSIT; and, as each condition is satisfied, the
SPEED commands are diminished to cause the head to slow down smoothly until it has reached the
correct position. At this point, carriage motion stops and the program enters the INPUT routine if the
count is zero. If it is not zero, the print bit is checked and if it is cleared, an LF is indicated and a speed
of 0 in/sec is commanded to complete the LF function. If the print bit is set however, WD CNT is
checked to see if a positive speed of either +3 or +6 is required to print the current character without
losing the next character.
4.1.6 INPUT Routine
The INPUT routine (Figure 4-6) checks U ART
data available (DA) and, if cleared (no character), it steps immediately to the BELL routine. If
DA is set, the program checks WD CNT to see if
the character buffer is full (WD CNT = 15). If
so, it ignores any input from DA, using the
U ART as the 16th memory location, and proceeds immediately to service the bell.

INPUT

NOTE
The UART can act as the 16th memory location
for up to 33 ms even though data is available. After
this period, the character will be lost when the
UART writes in another character.

.. ,1i

If WD CNT is not equal to 15, word count is
incremented, write address is incremented, the
character is put into the buffer at the new write
address, and UART DA is cleared as the program proceeds to the BELL routine.

WDCNT:WDCNT+1

CBA:WTADR
CB (CBA]:UARTOUTPUT
CLRUARTDA
CBA: - RDADR

CP·1629

Figure 4-6 INPUT Routine

4-12

4.1.7 BELL Routine
The BELL routine (Figure 4-7) turns the bell on for 106 ms and off for 106 ms, for each bell that is
received and stored in the bell status location in the control RAM.
If bell status is zero, no bells are required and the routine falls through to check count, print, and word
count. Here the decision is made to process either a print, an LF, or the next character, or to execute an

Lev.

-0

CP·1630

Figure 4-7

BELL Routine

4-13

If bell status is not zero, the status is checked to see if it is odd or even (for each bell code received, two
counts are stored in status, one to turn it on and one to turn it oft).

The bell timers in location 15 and 16 provide 4 bits of each count. The bits in either location 15 or
location 16 are incremented during each pass until that timer has reached zero {106 ms} and bell status
either becomes odd and the bell is turned off, or even and the bell is turned on. Each pass through the
loop takes 416 f.LS and it takes 256 passes to fully cycle each timer, providing 106 ms of on-time and 106
ms of off-time. Each time a timer reaches zero, one is subtracted from bell status until the total number
of bells commanded has been executed.
4.1.8 PRINT Routine
Before entering the PRINT routine {Figure 4-8}, the program sequenced through the BELL routine
where it found that the count location was not zero and that the print bit in location 12 was set,
indicating that a printable character was in the buffer. These conditions caused the program to enter
the PRINT routine.
Upon entering the PRINT routine, the program checks the position locations to be sure that they are
all equal to zero. This is done to prevent the start of print at some position other than the beginning of
the character cell.
The program checks position from low order through high order in 4-bit bytes, and if any are nonzero, it checks count and returns to the POSIT routine, looping until count is less than the seven dot
positions of a character. At this point, it sets count to zero, loops once more through POSIT, and
returns to PRINT.

In this pass, the program drops through to check count again. This time count should equal 8 as set in
the NEXT routine. The program verifies this by checking the MSB of location 11 in the control RAM.
If this bit is set, it signals the start of print {meaning that the head should start moving to the right}. To
start this motion, the program subtracts one from position error, sets count to 7 {to prevent a repeat of
this branch}, and returns to POSIT to loop through again so that the SPEED routine can command
head motion.
This time through, POSIT is still 0 relative to column, and count is less than 8 {7}; the program presets
the print timers, and clears the increment indication. It waits then for increment to set, and when it
does, it sets the 600 f.LS head drive enable {HOE}.
NOTE
At all other times through this routine, operation is
synchronized on the 416 f.LS clock, but at this point
continuation of program flow is predicated on the
fact that an incremental motion of the head has been
accomplished.
The 600 f.LS HOE is then timed out in PT 1 and PT2 locations of the control RAM on the 1.184 f.LS
instruction timing cycle of the microprogram. During this time, the character is printed. At the end of
that time, HOE is cleared, print is reset to 1, count is set once again to -1, and the program reenters the
POSIT routine.

4-14

..0

-0
600 "S TIMED ON
THE 1.114 "S
INSTRUCTION
CYCLE TIME OF
THE MICRO·
PROGRAM.

-0

~IGURE 4·3)
CP·1631

Figure 4-8

PRINT Routine

4-15

4.1.9 LINE FEED (LF) Routine
If, while passing through the BELL routine, count was not equal to 0 and the print bit in location 12
was cleared, the program enters the LINE FEED routine (Figure 4-9).
Upon entering the routine, the program finds count equal to 9 (as set in the NEXT routine) and a
preset in LFI and LF2. On the trailing edge of the 208 ILS clock, the LF motor is pulsed and the
program returns to POSIT.
Upon reentering the LF routine, the program checks count and if 8 or more, it checks to see if it is odd
or even. If even (as it should be 8), it decrements count and uses the timers LFI and LF2 to count out
7.5 ms. At this time, a second pulse is sent to the LF motor. If count had been odd, a count of 7 would
be indicated and 6.8 ms would be counted before a motor pulse was issued.
The program then counts 3.7 ms and issues a pulse, and then 8.2 ms. This time it sets LF HOLD and
returns to find count equal to O. This completes the subroutine that issues four discrete motor pulses to
step the motor one line increment and then issues the HOLD signal as part of the last increment.

4-16

C----.,LFPr---')
<8

EVEN

ODD

LFP2

-0

CP-1632

Figure 4-9

LINE FEED Routine

4-17

4.1.10 Lev Routine
If, while passing through the BELL routine,
both count and word count were found to be
zero, the program enters the LCV routine (Figure 4-10) and places an initial count into LCV
status.

LCV

This routine uses the LCV status (location 14),
the print timer in location 12 (since printing is
not being done), and locations 5 and 6 in parallel. The latter two locations are normally used as
read and write addresses, but they are not
needed in this case, so they can be used in parallel to maintain their equality so that the next
time they are required they will function to keep
a proper tally on the character buffer.
These combined locations then form a 12-bit
counter to count the 1.3 second time delay
before the head is commanded to move 4 columns to the right by setting -4 into position
error.
When the next printable character is sensed in
the NEXT routine, the LCV status is checked
(after a check for column 132) and, if found
zero, causes a +4 to be put into position error to
move the head back to printing position. At this
time it also initializes LCV status so that it will
count the 1.3 seconds the next time it is needed.
From this, it can also be seen that LCV ceases
and the same initialization of LCV status occurs
if a printable character is received during LCV
timeout.

CP·1633

Figure 4-10 LCV Routine

4.1.11 NEXT Routine
If, while passing through the BELL routine, count was zero but word count was not equal to zero, the
program enters the NEXT routine (Figure 4-11).
The program first decrements the word count, then increments the read address, and puts that read
address into the character buffer address (CBA) register causing the character stored at that address to
be exposed to the character generator ROM. The ROM is designed to output an additional bit that
when set indicates that the character is printable and when cleared indicates that the character is not
printable.
4-18

C8 X 16 + 4 - 1321
IGNORE CHAR
AFTER COL 132

COL-64

CP-1634

Figure 4-11 NEXT Routine
(Sheet 1 of 2)
4-19

#1 15 ,,51
"0

-{!FIGURE 4-91

CP·1634

Figure 4-11 NEXT Routine
(Sheet 2 of 2)

4-20

If column does not equal 132, column is incremented and examined again; this time to determine if the
head is now at column 64 (since a bell tone must be sounded at this point if the keyboard is in use).

Since 64 is a multiple of 8, it is only necessary to check for an overflow from the low order of column to
the high order. The program first checks LCV status and, if zero, sets 4 in position error. It then puts 4
in LCV status, sets count to 8, and increments the low order of column. If COL LO is not zero, the
program returns to POSIT. If it is now zero, the high order of column is incremented. If, at this time,
COL HI does not equal 4, the program returns to POSIT and when it gets to the PRINT routine, it
begins laying down the dots for the character.
If COL HI is equal to 4 after it is incremented, column 64 is indicated and the program checks KBH. If
it is not set, the program progresses to POSIT and proceeds through the normal print sequence. If
KBH is set, the program adds 2 to bell status, returns to POSIT, and rings the bell.

At this point, the program enters one of four subroutines to process one of five possible conditions.
If the character is not printable, and it is neither a CR, LF, BELL, or BS, the program exits and
reenters POSIT because the character falls within the control character category that requires no
machine action.
If the non-printable character is an LF, the program enters that subroutine. Count is set to 9 and the
proper preset is put in the line feed timer locations before progressing to the LINE FEED routine.
If the non-printable character is a BELL, two is added to the status and the program exits to POSIT.
If the non-printable character is a BS, the program enters that subroutine, where one is subtracted
from column (provided the head is not at column zero) and adds one to position error. The program
then returns to POSIT and then to the SPEED routine where the carriage is commanded to move one
space to the left.
If the non-printable character is a CR, the program enters that subroutine. It immediately clears
keyboard hold (KBH) and examines the low order bits of the column locations.

The function of this routine is to set column to zero (since that is where the carriage should be) and to
modify the position location by a factor equal to the number of columns away from column zero that
the head is actually situated when a CR is received.
This is done in the routine in two parts: first, the low order bits are examined and then the high order
bits are examined. Each column byte is then decremented and each position byte is incremented until
the operation is complete. The maximum number of passes through this loop is 32, which requires 100
J.LS of time to complete the subroutine.
If the print bit indicates that the character is printable, the program determines whether or not the
carriage is at column 132. It does this by determining that COL HI is ;>8 and that COL LO is ;>4. If
these conditions are true, printing cannot occur and the program returns to POSIT, ignoring the
current character until a CR occurs.

4.2 TIMING
The timing of all operations in the LA36 is derived from a crystal clock which operates at 1.6896 MHz.
The clock output frequency is divided by 2 to form the 1.184 J.LS cycle time for the MPC. Additional
divisions provide timing pulses for the carriage servo system and the data communication at 300 baud,
150 baud, and 110 baud. A division of the clock rate is also used by the MPC for timing the LF, BELL,
LCV, and INIT functions. Timing diagrams are provided in the applicable paragraphs of this chapter.
4-21

4.3 M7722/M7723 CONTROL LOGIC
The LA36 control logic is implemented as a MPC. A block diagram of this logic is shown in Figure 412.
Characters from the keyboard system or the data communications interface are processed through the
UART, to the character buffer under control of the MPC. This buffer accumulates characters during a
carriage return, eliminating the need for fill characters. Printing speed is doubled after a carriage
return to catch up with the. accumulated characters.
The MPC causes characters in the buffer to be presented to the character generator ROM on an FIFO
basis. The character generator ROM generates the dot matrix for the printable characters and contains
control character decode information for the non-printable characters. It also provides a printable/non-printable indication to the MPC.
The MPC activates the carriage servo system and the print head system in order to move the print head
through a character cell and print the seven columns of seven dots that form the printable characters.
Upon detection of a CR character, the MPC activates the carriage servo system to move the print head
to the left margin. Similarly, a BS character causes the print head to move one character position to the
left.
Upon detection of an LF character, the MPC activates the LF stepper system in order to advance the
paper one line.
In response to a bell character or as an end-of-line warning, the MPC activates the bell system in order
to produce an audible tone.
Transmission of characters from the keyboard, through the UART, to the data communications interface is done without microprogram control. The act of transmitting a character is stored in the KBD
HOLD flip-flop. The MPC generates the end-of-line warning only on lines in which the KBD HOLD
flip-flop has been set.
The structure that allows microprogram control of the LA36 operation is illustrated in Figure 4-12.
The microprogram consists of a sequence of 512 instructions that reside in the control ROM. Each
instruction consists of eight bits. The upper four bits define the general class of instruction; the lower
four bits define the particular operation to be performed.
Selection of a particular instruction in the microprogram is performed by the program address register.
This register generally acts as a counter, thus causing instructions to be executed sequentially at the
rate of one every 1.184 ,."s.
The sequential instruction flip-flop may be interrupted by instructions of the classes referred to as
JUMP1, JUMP2, JUMP3, CLR, SKIP1, and SKIP2.
The JUMPI instruction causes the address control logic to be activated in order to load the lower four
bits of the instruction (ROM data bus) into the lower four bits of the two-program address register.
Any transfer of control that does not change the upper five bits of the address may use this instruction
and is thus limited to use for jumps within anyone of thirty-two 16-word pages of the microprogram.
The JUMP2 instruction has the same effect as the JUMPI instruction except that it also uses the 4-bit
data bus register to load the next 4 bits of the program address register. Thus, the combination of an
instruction that loads the register (described below) and a JUMP2 instruction can affect a transfer
within one of the two 256-word halves of memory.
4-22

STEPLF--~

KEY
STROBE

SERIAL

t~~~~

SERIAL
INPUT-I

PNTABL
CP ~'571

Figure 4-12 Control Logic Block Diagram
The JUMP3 instruction is similar to the JUMP2 instruction with the additional effect that the most
significant bit of the address register is toggled. This causes the jump to be to the opposite half of
memory as the instruction being executed.
The CLR instruction resets the contents of the program address register to zero. The program address
register is also reset to zero on power-up.
4-23

The SKIPl and SKIP2 instructions are conditional skip instructions. The conditions are the inputs to
MUXI and MUX2. The lower four bits of the skip instruction specify which of 16 inputs to sample. If
the selected input is asserted when the skip instruction occurs, then the address control logic causes the
address to increment by two rather than by one during a single instruction cycle. Signals that are inputs
to the skip multiplexers are UART DA, KBH, servo control data (CARRY, BORROW, INC), each
of the four bits of REG (BITO, BIT1, BIT2, BIT3), the control character indications (CR, LF, BS,
BELL), the printable indication, the REG equals 0 indication, and a real-time clock.
Instructions that do not modify the normal sequential flow are BRING4, BRINGl, STOREl, and
DEC 1.
The BRING4 instruction performs an immediate load of data from the lower four bits of the instruction to the 4-bit register (REG). This is accomplished by enabling the 4-bit gate and loading the
register.
The BRING 1 instruction is used to fetch data from one of sixteen 4-bit memory locations in the
control RAM to the REG. The lower four bits of the instruction select the memory location. The
instruction is executed by enabling and loading the memory.
The DECI instruction is the means by which the MPC transmits commands to the systems that it is
controlling. The lower four bits of the instruction specify which of 16 outputs of the DECI decoder
will be pulsed. The outputs of the decoder are CLR UART DA, CLR KBH, CLR carry /borrow, CLR
INC, CLR HDE (combined with CLR INC), SET HDE, LOAD CB Address, WRITE BUFFER, +1
REG (adds I to REG), -I REG (subtracts I from REG), SET BELL, CLR BELL, Load DAC (D/A)
(commands speed to servo system), CLR INIT (sets left margin at power-up), STEP LF, and SET LF
HOLD.
4.4 KEYBOARD SYSTEM
A simplified diagram of the keyboard system logic is shown in Figure 4-13. The keyboard system
generates the 7-bit, parallel ASCII codes listed in Table 4-3. These codes are stored in a 3600-bit ROM
that is controlled by an internal 10-20 kHz clock. The ROM has a scan cycle time of 6.5-9 ms. It is
addressed asynchronously by' X and Y pulses from the key matrix or the numeric pad. The X and Y
addresses (Table 4-4) for the numeric keypad are unique. This is due to the fact that the same characters are generated in the shifted and un shifted mode.
When a key switch is closed for at least 6 ms, the X and Y pulses address the corresponding character
cell in the ROM. The timing for character processing is shown in Figure 4-14. After a 2.5-5 ms delay (3
ms nominal) to ensure that the switch closure did not result from contact bounce, a DATA READY
pulse lasting one ROM clock period (50-100 #LS) is output by the ROM. This pulse is gated to the pulse
shaper and differentiated to produce a 350-750 ns STROBE pulse, which strobes the parallel data to
the UART. The STROBE pulse is also applied to the strobe repeat generator together with the AKD
(any key depressed) logic level. If the REPEAT key switch is closed while another key switch is closed
(except SHIFT, SHIFT LOCK, CTRL, and TAB), the strobe repeat generator produces a series of
pulses, one every 46-86 ms. These pulses are gated with the repeat logic level and the DATA READY
pulses to repeat the STROBE at a rate of 15 per second as long as the REPEAT key is closed. The
repeat logic level is also applied to the ROM to lock out all other key closures during a repeat.
When the 64/128 switch is open, data bit 6 is gated out. Consequently, only uppercase character codes
are strobed to the UART.
The SHIFT, SHIFT LOCK, and CTRL key switches inhibit bits 6 and 7 in the ROM so that upper
level character codes or control codes are output when these keys are closed. The delete code is unaffected by these key switches.

4-24

BIT I
BIT 2
BIT 3
BIT 4
BIT 5
BIT 7

CONTROL

CTRL
KEY

KEY
MATRIX

XO/YO

XIIYI
X2IY2
X3/Y3
X4/Y4
X5/Y5
X6/Y6

B2
B3
B4
B5
B6
B7

X7/Y7

STROBE

X8/Y8

CG
ROM

~
~
X6
Y4
Y5

KEY 1KEY 7
UART
MPC6

-L

DATA READY

1 STROBE
I (K EY

PULSE
SHAPER

STB HI

f--~

Y6
CLOCK f---

SHIFTISHIFTt
LOCK KEY

BIT 6

64/128

nAY

NUMERIC
PAD
LK03

r---w-

SHIFT

7
STROBE
REPEAT
GENERATOR

AKO

1LOCKOUT

rD- I

BREAK
KEY

II BREAK + L GATE MPC5

REPEAT
KEY

CP-1578

Figure 4-13

LK02/LK03 Keyboard Logic Diagram

Table 4-3

Key
Esc

2
r

[
,

=
I

Keyboard ROM Addressing

ASCII Code
b7-bl

Octal
Code

0011011
0110010
1110010
1101000
1011011
0101100
0111101
0110001
1100101

33
62
162
150
133
54
75
61
145

4-25

ROM Addressing
Y Line
X Line

7
5
3
2
I

0
7
5

9
8
6

4
3
2
I
9

Table 4-3
Key
g

m
0

w
f
n
-

9
q
d

BS
8

P
s
v
7
0

a
c

SP
6
i

{
x
5
u

CR
I

z
4

Y
,
k
\

/
HT
3
t

DEL

Keyboard ROM Addressing (Cont)

ASCII Code
b7-bl

Octal
Code

1100111
1101101
0110000
1110111
1100110
1101110
0101101
0111001
1110001
1100100
1100010
0001000
0111000
1110000
I IIOOII
1110110
0110111
1101111
1100001
1100011
0100000
0110110
1101001
III 101 I
0111011
1111000
0110101
1110101
0001101
1101100
0001010
1111010
0110100
III 100 I
0100111
1101011
1011100
0101111

147
155
60
167
146
156
55
71
161
144
142
10
70
160
163
166
67
157
141
143
40
66
151
173
73
170
65
165
15
154
12
172
64
171
47
153
134
57

3
I
7
5
3
I
0
7
5
3
I
0
7
5
3
I
7

I
0

0001001
0110011
1110100
1101010
1111111
0101110
1100000

I1
63
164
152
177
56
140

7
5
3
2
I
0

7
5
3
2
1
0

4-26

ROM Addressin2
X Line
Y Line

5
3
I

8
7
5
4
3
I
7
5
4
3
2
I
7
5
4
3

5
3
0

8
6
4

3
I
9
7

5
4

2
0

8
6
3
I
9
7
5
4

2
I
0

8
5
3

2
I
0
9
6
4
3

Table 4-3

Key

ESC
(U'

R
H
]

<
+
!
E
G
M
)

F
N

(
Q
D

B
BS

P
S
V
&

a
A
('

SP
1\

}
X

%
U

CR
L
LF
Z

Keyboard ROM Addressing (Cont)

ASCII Code
b7-bl

Octal
Code

0011011
1000000
1010010
1001000
1011101
0111100
0101011
0100001
1000101
1000111
1001101
0101001
1010111
1000110
1001110
1011111
0101000
1010001
1000100
1000010
0001000
0101010
1010000
1010011
1010110
0100110
1001111
1000001
1000011
0100000
1011110
1001001
1111101
0111010
1011000
0100101

33
100
122
110
165
74
53
41
105
107
115
51
127
106
116
137
50
121
104
102
10
52
120
123
126
46
117
101
103
40
136
III
175
72
130
45

8
7
5
3
2
I
0
7
5
3
1
7
5
3
I
0
7
5
3
I
0
7
5
3
I
7
5
3
1
8
7
5
4
3
I
7

9
8
6
4
3
2
1
9
7
5
3
0
8
6
4
3
I
9
7
5
4
2
0
8
6
3
I
9
7
5
4
2
I
0
8
5

1010101
0001101
1001100
0001010
1011010

125
15
114
12
132

5
4
3
2

3
2

4-27

ROM Addressing
X Line
Y Line

0
9

Table 4-3
Key
$
Y

"
K
I
I

?
HT

#
T
J
DEL

>
......

Keyboard ROM Addressing (Cont)

ASCII Code
b7-bl

Octal
Code

0100100
1011001
0100010
1001011
1111100
0111111
0001001
0100011
1010100
1001010
I 11 I I II
0111110
1111110

44
131
42
113
174

77
II
43
124
112
177
76
176

ROM Addressin2
XUne
Y Line
6

7
5
4
3
2
I

4
3
2
1
0

7
5

7
5
3
2
I
0

3
2
I
0

CONTROL MODE
ESC
DC2
DC2
BS
ESC

FF
GS
DCI
ENQ
BEL
CR
OLE
ETB
ACK
SO
CR
EM
DCl
EOT
STX
BS
CAN
OLE
DC3
SYN
ETB
SI
SOH

0011011
0010010
0010010
0001000
0011011
0001100
0011101
0010001
0000101
0000111
0001101
0010000
0010111
0000110
0001110
0001101
0011001
0010001
0000100
0000010
0001000
0011000
0010000
0010011
0010110
0010111
0001111
0000001

4-28

22
22
10
33
14
35
21
5
7
15
20
27
6
16
15
31
21
4
2
10
30
20
23
26
27
17
1

7
5

3
2

9
8
6

4
3

0
7
5
3
I
7
5
3
I
0
7
5
3
I
0
7
5
3
I

I
9

7
5
3

3
1

7
5

3
0

8
6
4
3

I
9
7
5
4
2
0

8
6

Key
ETX
NUL
SYN
HT
ESC
ESC
CAN
NAK
NAK
CR
FF
LF
SUB
DC4
EM
BEL

vr
FS
SI
HT
0('3
0('4
LF
DEL
SO
NUL

Table 4-3 Keyboard ROM Addressing (Cont)
ASCII Code
Octal
ROM Addressig
b7-bl
Code
X-L1ne
YLine
0000011
0000000
0010110
0001001
0011011
0011011
0011000
0010101
0010101
0001101
0001100
0001010
0011010
0010100
0011001
000011 t
0001011
0011100
0001111
0001001
0010011
0010100
0001010
1II1 II I
OOOJIIO
0000000

3
0
26
II
33
33
30
25
25
15
14
12
32
24
31
7
13
34
17
II
23
24
12
177

I
8
7
5
4
3
I
7
5
4
3
2
I
7
5
4
3
2
I
8
7
5
3
2

8
7
5
3
2
I
0
7
5
3
1
7
5
3

9
8
6
4
3
2
I
9
7
5
3
0
8
6

7
5
4
2
I
0
8
5
3
2
I
0
9
6
4
3
2
I
0
8
7
5
3
2

SHIFT AND CONTROL MODE
ESC
NUL
DC2
BS
GS
FS

vr
SOH
ENQ
BEL
CR
HT
ETB
ACK

0011011
0000000
0010010
0001000
0011101
0011100
0001011
0000001
0000101
0000111
0001101
0001001
0010111
0000110

33
0
22
10
35
34
13
I
5
7
15
II
27
6

4-29

Table 4-3
Key
SO
US

BS
DCl
EOT
STX
BS
LF
OLE
DC3
SYN
ACK
SI
SOH
ETX
NUL
RS
HT
GS
SUB
CAN
ENQ
NAK
CR
FF
LF
SUB
EOT

EM
STX

vr
FS
US

HT
ETX
DC4
LF
DEL
RS
RS

Keyboard ROM Addressing (Cont)

ASCII Code
b7-bl

Octal
Code

0001110
0011111
0001000
0010001
0000100
0000010
0001000
0001010
0010000
0010011
0010110
0000110
00011 II
0000001
0000011
0000000
0011110
0001001
0011101
0011010
0011000
0000101
0010101
0001101
0001100
0001010
0011010
0000100
0011001
0000010
0001011
0011100
0011111
0001001
0000011
0010100
0001010
1111111
0011110
0011110

16
37
10
21
4
2
10
12
20
23
26
6
17
I
3
0
36
II
35
32
30
5
25
15
14
12
32
4
31
2
13
34
37
II
3
24
12
177
36
36

4-30

ROM Addressine
XUne
YLine
1
0
7
5
3
I
0
7
5
3
I
7
5
3
I

8
7
5
4
3
I
7
5
4
3

4
3
I
9
7
5
4
'1

8
6
3
I
9
7
5
4

2
I
0

8
5
3
'1

I
7
5
4
3
2
I

I
0
9
6
4
3
2
I
0

7
5
3
2
I
0

Table 4-4
Key
1
2
3
4
5
6
7
8
9

ENTER

Numeric Keypad ROM Addressing

ASCII Code
b7-bl

Octal
Code

0110001
0110010
0110011
0110100
0110101
0110110
0110111
0111000
0111001
0110000
0101110
0101100
0101101
0001101

61
62
63
64
65
66
67
70
71
60
56
54
55
15

ROM Addressin2
x Line
Y Line
6
6
6
4
4
4
2
2
2
0
0
1
0
4

4
5
6
4
5
6
4
5
6
5
6
2
3
2

Y0-Y8

STROBE DELAY

I
I
DATA READY

----~I~I------------------------~

STROBE

------~Irl----------------------------~----DATA (BIT I-BIT 7)

------~II~------------------------~
CP-1615

Figure 4-14

Keyboard Timing Diagram

4-31

4.5 DATA COMMUNICATIONS INTERFACE
A simplified diagram of the data communications interface is shown in Figure 4-15. Timing is shown
in Figure 4-16.

.13

LINE

20MA
~=-_--1 LOOP

RCVR

M..;;;.LO;...;..",;",--_...,

PRINTER

....._-.......

CONNECTS
TO STANDARD
CURRENT
LOOP
INTERFACE

I
I

: _L-IN-E--+-......-------ir--t

L--=-__,I

~~:

DRVR

t---t-e

LOCAL_

LO~CAL

r
- 1
I ACTION OF I
: LINEI LOCAL:
LS!,!..T£H__

)

. .J

LOGIC
BOARD
CONNECTORS

.14
-RCV
}
-XMIT

CONNECTS
TO OPTIONAL
INTERFACE
CP-1163

Figure 4-15

Data Communications Interface Diagram

i""1-1------- 66.6 ms ------.~I

~1-~-----looms------.~

I
I
I
I

11
START
BIT

8
DATA
BITS

LSB

1 I
STOP
BIT

11
START
BIT

150 BAUD

I [ T-rT-r"'T""-r_r

---,~IL. . L_r~t~T:~_T: :_T~:~: T. I.:~ -r:;: : _T~:~;:.;:.-~r:~r: . .J~i----l I- 6.66ml
!

I 1
START
BIT

I [
,-A-, ,

2
STOP
BITS

I
I

-l I- 9.09ms
33.3 ms -------.~I

8
DATA
BI;rS

PARITY

I
I
I
I
I

1 I
STOP
_ _ BIT

MSB~

300 BAUD

T _r _r T I I
\,-A-,

"'T' "'T' "'T'
I
I
,

I
I
I
I
I
I
I
I
I
I
I
L....L--LI......JIL.-.L.I--I.'~I_.L.I......
1 ___ ...L .J

LSB

I
I
,

110 BAUD

~~------~---T-TV-~~

11 .. ------

8
DATA
BITS

LSB

I
I
,

I
I
"

I
I

,
I
...J

-l I- 3.33ms
CP-1177

Figure 4-16 Data Communications Interface Timing Diagram

4-32

4.5.1 20 IDA Loop Receiver
A simplified diagram of the loop receiver is shown in Figure 4-17. Signal line current can be up to 80
mAo Higher currents will activate the zener diode, which limits the receiver voltage drop to 1.6 V for
currents up to 1 A. Any current over 15 mA is interpreted as a mark; any current under 3 mA is
interpreted as a space. Isolation of 1500 V is provided by the photo isolator.

+5
PHOTO
ISOLATOR:.....+_ _...L

TRANSMIT

BREAK/LINE/ S.O.
LOCAL GATES ....;..;.;c_--,
MPC5
CP-IS79

Figure 4-17

20 mA Loop Receiver Diagram

4.5.2 20 mA Loop Driver
A simplified diagram of the loop driver is shown in Figure 4-18
Isolation of 1500 V is provided by the photo isolator. The circuit goes to the mark state for currents as
low as 20 mA when the MPC is idling or when the LA36 power is turned off. Signal line current must
be limited to 80 mAo Voltages exceeding 40 V should not be used to drive the loop.

+5V

S.I.
RECEIVE

BREAK/LINE /LOCAL
GATES
MPC5

CP-ID80

Figure 4-18 20 mA Loop Driver

4-33

4.6 CLOCK LOGIC
The clock frequencies used to time the MPC are obtained as shown in Figure 4-19. All frequencies are
derived from a crystal oscillator and shaper that generates a 1.6896 MHz square wave. This signal is
divided down by two ripple counters, a + 11 binary counter and a + 15 binary counter to produce the
necessary timing signals and baud rate signals. The frequencies and time periods produced are shown
in Table 4-5. Important timing relationships are shown in Figure 4-20.
592n.

+5V

ClK H

ClK l
1.184m.

+5V

1.6896MHz
CLOCK

RO .:t..L
ClK 0
RIPPLE
COUNTER
';'16
R3
,ClKI

RO ';'2
r - - ClK 0
RIPPLE Rl ~
COUNTER
';'4
ClK I
R2
R3 ~

';'15
BINARY
COUNTER
ClK
MSB

1.76 KHz

208H
76,._
19l

' - - ClK

MSB

+11
BINARY
COUNTER

4.8KHz

150,._
.......J~58r,..... ,..
~

I- ,.--1
208

CP-III8I

Figure 4-19 Clock Logic

592 n.

1.184 ,..

ClK

~50ns

L
L

n
.i

Jl
i.

1.184,..

CP-I616

Figure 4-20 Clock Timing Relationship
4-34

Table 4-5 Clock Frequencies and Time Periods

Frequency

Time Period

1.6896 MHz

592 ns

844 kHz

1.184 JlS

844 kHz (eLK)

50 ns pulse /1 .184 JlS time period

106 kHz

9.4 JlS

53kHz

18.8 JlS

26.5 kHz

37.7 JlS

13.25 kHz

75.5 JlS

4.8 kHz

208.3 JlS

2.4 kHz

416.7 JlS

1.7 kHz

588.2 JlS

4.7 UNIVERSAL ASYNCHRONOUS RECEIVER/TRANSMITTER (UART)
A simplified diagram of this logic is shown in Figure 4-21. Depending on the operating mode (local or
on-line), ASCII data is applied to the UART from the keyboard system or from the data communications interface. Keyboard data is 7-bit parallel ASCII. Interface data is serial.
Initially, the CLR R DONE flip-flop and the UART are cleared by the WAKE-UP (WU) pulse from
the wake-up circuit. During on-line transmission, parallel data from the keyboard are transferred to
the UART by KEY STB H and converted to serial data, which is applied to the data communications
interface. In the local mode, the serial output of the UART is gated directly back to the serial input.
Consequently, no data is transmitted but a mark is sent to indicate that the terminal is not active.
Incoming data is locked out by the gating.
In either mode, the serial input data is assembled and converted to parallel data by the UART. Then,
the UART outputs a DA flag to notify the MPC which issues a WRITE BUFF pulse. This pulse sets
the CLR R DONE flip-flop. After the character has been stored in the character buffer, the MPC
issues a CLR DA pulse. This pulse clocks the CLR R DONE flip-flop, which clears R DONE in the
UART so that the next character can be processed.
4-35

R
DONE

ClR
R DONE

DECI MPC4
KEY 7

":"

KEY 6

ClR DA l

KEY 5
KEY 4
KEYBOARD

KEY 3
KEY 2
KEY I
KEY STB H

XD7

DATA
S.O. COMMUNICATIONS
INTERFACE
MPC5

BREAK +

XD5
XD4

UART

XD3
XD2
XDI
LDXD

RDI
RD2
RD3
RD4

S.l.

CB RAM
MPC 6

RD5
S.1.

+5V

MUX I
MPC 4

S.O.

XD6

WAKE UP W. U. l
MPCB
DATA COMMUNICATIONS
INTERFACF. MPC5

DA H

RD6
RD7

LINE/lOCAL

~
1.76KHz

CLOCK lOGIC
MPC5

ClKS

ROB
2SB

+5V

2.4KHz

BAUD RATE

4.B KHz

+5V

CP-1582

Figure 4-21 UART/Mode Selection
and Baud Rate Selection Logic

4-36

The rate at which characters are transmitted or
received by the UART depends on the baud rate
that has been selected by the BAUD RATE
switch. Three signals from the clock logic are
applied to the baud rate gates: 1.76 kHz, 2.4
kHz, and 4.8 kHz. These gates are controlled by
the BAUD RATE switch as indicated by the
truth table (Table 4-6). The selected signal is
applied to the clock inputs of the U ART.

Table 4-6 Baud Rate Switch Connections

A BREAK from the keyboard will interrupt the
mark on the serial output line. This is the serial
equivalent of sending a start bit, followed by a
continuous space and no stop bit, which is often
interpreted as a transmission interrupt by the
receiving device.

Function

J2-V

150 Baud

300 Baud

110 Baud

4.8 CHARACTER BUFFER/GENERATOR AND PRINT HEAD SYSTEM
A simplified diagram ofthis logic is shown in Figure 4-22. Characters from the UART are stored in the
character buffer RAM (CB RAM). This is a IS-character FIFO memory that is always read-enabled
because the ENB input is grounded. Characters are written into successive locations in the buffer by
the WRITE BUFF pulse from DECl.
SET HOE

,r-

DEC I
MPC4

CLR HOE

UART
MPC6

1
ENB
MO

DECI LD CBA
MPC4

-12.......
....

HS2 MPC6

]L
...
HS3 MPC6

..........

CSO

BB
AI

SOL2

SOL 4

SOL 5

SOL6

SOL7

PNTABL H

MUXI
MPC4

...
.........

HS6
MPC6

I ......
PTBL
L
MPC6

- -

B4
CHARACTER
HS5
GENERATOR
MPC6
ROM
B5

HS6
MPC6

+21 v

SOLI

SOL3~

1
HS4
MPC6

COL INC COUNT 0

HSI MPC6

CHARACTER
BUFFER
ADDRESS
REGISTER

V REF
REGULATOR

M2
CHARACTER
03 BUFFER M3
RAM
MO
DO

BUF HOE EN H

VREF

-21V

HD EN
(HOE)
MPC8

REG {
MPC4
-

1
-

HOE
C

WRITE BUFF

WR
DO

U"""'"

A2 A3

L....-

CONTROL
~
CHARACTER
DECODER ~

COL INC { COL INC COUNT I
COUNTER
MPC7
COL INC COUNT 2

lo...

MUX2
MPC4

HT
CP-'1I83

Figure 4-22 Character Buffer/Address Register/Generator and Print Head System
4-37

The read or write addresses of the character
location are stored in the character buffer
•
•
address register. Addresses are clocked to the
2
•
•
character buffer by LD CBA from DECl. Each
3
•
•
time a character is written or read, the corre
ROWS
4
sponding address is incremented by the MPC.
•
•
•
•
A[4:9]+CSO
As each character is read from the buffer, it is
(ASCII CODE) 5
•
•
decoded by the character generator ROM (CG
6
•
•
ROM), which is a 1024 X 8 ROM that stores a
7
dot matrix pattern in a cell for every printable
•
•
character and a unique code for each non-printH
P
N
T
A
B
L
8
able control character. Each character cell is
o I 2 3 4 !5 6 7
defined by a 7 X 7 dot matrix as shown in Figure
SUB COLUMNS
4-23. Rows are selected by the ASCII code,
A[I:3]
A(4:9) and CSO. Subcolumns are selected by the
(COL INC COUNT)
COLumn INCrement COUNT, A(1:3). The dot
CP-15'2
matrix is output to the solenoid amplifiers. The
first bit location in each row (subcolumn 0) conFigure 4-23 CG ROM Character Cell
tains all Os. All bits in the eighth row are used to
identify printable and non-printable characters.
This row contains all 1s for printable characters
and all Os for non-printable characters. There is one multistage amplifier for each solenoid. These
amplifiers convert the head select logic levels (HS 1 to HS7) to drive current for the solenoids. The last
stage of the amplifier is clamped to +60 V by a zener-controlled voltage regulator. This reduces the
effects of the voltage produced by the inductive load of the solenoid and ensures that the wires retract
completely between subsolumns.
y

Solenoid current is regulated by the VREF regulator. This regulator provides a constant current
source for uniform density of character impressions, regardless of resistance and temperature
variations.
The dot pattern is synchronized with the position of the print head by the COL INC COUNT as
shown in Figure 4-24. The print head solenoids are fired according to the position of the print head.
The MPC continuously checks the printable character indication (PNTABL H) in MUXI and sends a
head enable (HD EN) pulse to the amplifiers when the print head is at a subcolumn boundary. Each
time this pulse is received, the appropriate solenoids are fired and a subcolumn of dots is printed.

4-38

COL INCREMENTS
I

CARRY--,

rCARRY

+ ~ + + +++++++
~• _ _ _ CHARACTER BOUNDARY_ _--t_1

•
•
•
•

31
ROWS
(SOLENOIDS)

1"- -

r- -

•

r- r
L_

•

•
•
•
•
•
•
•

•

...,

(0'· HEAD MOTION)

r11

COL INC COUNT
(HEAD POSITION)

HEAD TRAVEL

1
-~

--j
1

1
1

--,

1
---i
1
....J

.,.
CHARACTER
SPACING

CP-tS811

Figure 4-24 Print Head Operation

Dots are never printed in subcolumns 0, 8, and 9. These subcolumns are used for the fixed spacing
between characters. The dot patterns are arranged so that two dots never print in the same row of
adjacent subcolumns. This ~nsures consistent dot quality and optimizes solenoid power consumption
by allowing the solenoids to retract completely before they are fired again.
When the MPC detects a non-printable indication (PNTABL L), it does not send a HD EN pUlse.
Instead, the character is decoded by the control character decoder. Only four of the seven bits from the
CG ROM are needed to identify the four control characters: backspace (BS), line feed (LF), carriage
return (CR) and bell (BEL). These codes are applied to MUX2 and processed by the MPC.

4-39

4.9 CARRIAGE SERVO SYSTEM
A block diagram of the carriage servo system is shown in Figure 4-25. The speed and direction of the
carriage motor are determined by the speed data from the MPC. This information is stored in the
speed register. When a change of speed is required, the appropriate data is generated by the MPC and
loaded into the register by LOAD DA L from DECI. The various possible combinations of SPEED
commands are shown in the truth table in Table 4-7. This register is cleared by WU L during wake-up
(Paragraph 4.12). The speed data in the speed register is applied to the summing network together with
the output of the + and - TACHs. The sum of these voltages is amplified and smoothed by theoperational amplifier and the feedback networks; the result is a dc voltage called SUM. This voltage is
amplified by the power amplifier to produce the current required to drive the carriage servo motor. A
positive voltage drives the motor clockwise, moving the carriage forward from left to right. A negative
voltage drives the motor and the carriage in the opposite direction.

-~ 9
+Is~p

REG OH
REG lH

SPEED!
DATA
REG 2H
REG
MPC4
REG 3H

SPEED
+

SUMMING
NETWORK

POWER
AMP

CARRIAGE
SERVO
MOTOR

AMP

+
ENCODER

LOAD
DE C lOlA L
MP C4

PTI

WAKE UP W. U.L
MPC e

-INC

I FWD

-TACH
CLO CK 76,.sec
LOG IC
MP C5

_'=1

MUX 1 H
MPC4
CARRY/BORROWl
MUX 2 B H
GENERATOR
MPC4
DEC 1 CLR C/B
MPC4

INCREMENT
HOLD FIF

DEC 1 CLK HOE L
MPC4

CLOCK
L OGIC
M PC5

+INC

I REV

+TACH

PTI

ENCODER
SIGNAL
DETECTOR
PT2

L REV

COLUMN

~ INCREMENT I COUNT

MUX 2 INC H
MPC4

PT2

THRESHOLD
DETECTOR
AND
FILTER

I---

COUNTER

COL INC COUNT
TO CG ROM
MPC6

r"'"
592"s

CLK H
CP-1584

Figure 4-25

Carriage Servo System

4-40

The encoder on the motor shaft generates two feedback signals: PTI and PT2. These signals are
applied to the dual-channel threshold detector and filter, which converts them from sine waves to
square waves for processing by the encoder signal detector which is controlled by the CLK H, 1.184 ms
and 592 ns timing signals from the clock logic. The encoder signal detector produces a COUNT pulse
and logic level commands for the + TACH and the -TACH, which are clocked by a 76 f.LS timing signal
from the clock logic. The + TACH and -TACH produce 76 f.LS velocity feedback pulses, which are
algebraically combined (summed) with the SPEED command to smoothly correct the speed and direction of the motor. Increment data is stored in the increment hold (INC H) flip-flop. This flip-flop is
cleared by the CLR HOE L pulse from MPC4. Whenever the + or - TACH flip-flop is set, INC H is
clocked; thus providing data for the MPC, which uses it to synchronize the printed dots with the
carriage position.
The COUNT pulses produced by the encoder signal detector are counted by the COL INC counter.
The output of this counter provides column position feedback data for the CG ROM. Counter overflow is stored in the carry/borrow generator to provide print head position change feedback data for
the MPC.
Table 4-7 MPC SPEED Command Truth Table
Register Information Loaded into DA
DA (+ = PRINT, - = RETURN MOTION)
REG3

REG2

REGI

REGO

(1)

Nominal
Speed (in/ sec)

0
0
0
0
0

0
0
0
0
1

0
0
1
1
0

0
1
0
1
0

+6
+3
0
-3.8
-7.6

-11.4

0
0
1
1
1
1
1
1
1
1

1
1
0
0
0
0
1
1
1
1

1
1
0
0
1
1
0
0
1
1

0
1
0
1
0
1
0
1
0
1

-15.2
19.0
-22.8
-26.6
-30.4
-34.2
-38.0
-41.8
-45.6
-49.4

4-41

4.9.1 Tachometer, Summing Network, and Sum Amplifier
Increment pulses are converted to velocity feedback by the tachometer logic shown in Figure 4-26.
When an increment occurs, it is stored in the appropriate TACH ·flip-flop. The increment data is
transferred to the flip-flops immediately, but the transfer of the TACH pulse to the summing network
may occur anywhere from 0 to 76 f.LS later, depending on the occurrence of the data with relation to the
clock signal.
The second positive transition of the 76 f.LS clock signal clears the TACH flip-flops, thus providing a 76
f.LS pulse to the summing network for each increment. The TACH flip-flops are inhibited on the first
increment following a direction reversal to keep the print head from oscillating.
The TACH pulses are algebraically combined with the SPEED command voltage in the summing
network. This network contains precision 1 percent resistors that produce weighted voltages from both
the TACH pulses and the SPEED commands. The TACH pulses are of opposite polarity from the
SPEED command voltages. Consequently, the feedback pulses oppose (buck) the SPEED commands.
The sum of the two voltages is amplified by the sum amplifier and fed back to the negative input of the
amplifier via the active low pass filter to smooth the TACH pulses. The result is an average dc voltage
(SUM) which produces feedback that exactly counterbalances the SPEED commands.

PTI
WINDOW

r---

DIR
HOLD
F/F

+
F/F

----

or-

;- -C

THRESHOLD
DETECTOR
MPC7

~r-

PT2
CLOCK

F/F
C
'-----

CL OCK
LO GIC
MP

761'sec

,:'(

REG lH

SPEED
DATA R
MPC4

+
TACH
C Of-

-0

.047UF

TACH

~~T

232K
SUMMING
NETWORK

-0

TACH

.:r~
I

~~ POWER
AMP

TACH
-C
Of--

REG OH

REG 2H

r--0
1

r---

- o

SPEED
REGISTER

REG 3H

+
+
CP -1585

Figure 4-26 Tachometer Logic

4-42

4.9.2 Encoder and Threshold Detector
The encoder circuit and mechanism are illustrated in Figure 4-27. The light sources from two lightemitting diodes (LEOs) are focused on a slotted disk that is mounted on the motor shaft in front of a
slotted mask and two infrared-sensing phototransistors. Rotation of the disk creates an interference
pattern that causes the phototransistors to generate two sine waves, PTI and PT2. These sine waves are
always 90 degrees out of phase as shown in Figure 4-27. When the disk rotates in the forward direction,
PTI leads PT2 by 90 degrees. PTI and PT2 are applied to two threshold detectors. PTI and PT2 are
approximately 0.5 to 1 V peak-to-peak centered around a threshold of approximately 4.5 V. When the
signal is above the threshold, the output is -0.7 V and when the signal is below the threshold, the
output is 3.9 V. These signals are filtered by an RC circuit and shaped into square waves by Schmitt
triggers. The Schmitt triggers logically invert the output of the threshold detectors, thus providing a
logic high for encoder levels above the threshold and a logic low for encoder levels below the threshold.
+5V..-----,

+ 5 V --'\1\,.,.....,....+"'-1

J~
DISK

o 90'
FWD -PTI LEADS PT2 BY 90'
REV - PT2 LEADS PTI BY 90'

PTt OR
PT2
>-""","..,....--1 SCHMIDT
TRIGGER
ENCODER
' - - _ - - - ' SIGNAL
DETECTOR
MPC7

MASK
PTI

PT2

CP-1591

Figure 4-27

Encoder and Threshold Detector

4.9.3 Encoder Signal Detector
The encoder signal detector contains four flip-flops: +, -, DIR HOLD, and COUNT. A simplified
diagram for this logic is shown in Figure 4-28. Incremental changes are detected by using PTI as a
window and PT2 as a clock as shown in Figure 4-29. Encoder square wave PTI is applied to the data
inputs of the + and - flip-flops and PT2 is applied to the clock inputs.
The + flip-flop is set by positive-going edges that occur during positive windows and the - flip-flop is
set by negative-going pulses that occur during positive windows. Direction reversals are latched by the
DIR HOLD flip-flop.
When either the + or - flip-flop is set, increment data is stored in the COUNT flip-flop. At time state
TI, this flip-flop is clocked by the negative-going edge of the 1.184 J.l.S pulse as shown in Figure 4-30. At
time state T2 the COUNT pulse is gated to the COL INC counter by CLK H.
At time state T3, the + and - flip-flops are cleared by the positive-going edge of the 592 ns pulse in
order to process succeeding increments.
4-43

r------------- FROM + TACH
REV
TO + TACH
t-------':.:..::.;'------}

PTI WINDOW

FWD

~-+___-+__+-____~}TO

THRESHOLD
DETECTOR
MPC7

-TACH

' - - - - - - - - FROM -TACH

COL INC
COUNT COUNTER AND
INC HOLD
MPCT

PT 2
CLOCK

CLOCK lOGIC _...;;5..;;,9..;;.2.;.;.ns"'---_ _ _ _ _ _ _ _ _ _ _ _ _ _ _--'
MPC5
ClK H
CP-I588

Figure 4-28 Encoder Signal Detector

DIRECTION
REVERSAL
PTI (WINDOW)

PT2 (CLOCK)

DIR HOLD F/F

+ TACH

t
t

TACH

CP-I&17

Figure 4-29 Increment Detection Timing

4-44

592

1.184,..

MPC5
CLK H

IJl

+ F/F
I
Til
- F/F

I
I

T21

T31

I
I
I
COUNT F/F

I
I
COUNT PULSE

I
I

OVERFLOW F/F

I
I
I

IL\

OVERFLOW PULSE

C/8 F/F

...-----411-1- - - - - - - - ,
SIGN F/F

CLR C/B L

----------------~\r\--------------,u
CP-16t8

Figure 4-30 Encoder Signal Detector and Column Increment Counter Timing Diagram

4-45

4.9.4 Column Increment Counter and Carry jBorrow Generator
A simplified diagram for this logic is shown in Figure 4-31; timing is shown in Figure 4-30. When
either the + or - flip-flop in the encoder signal detector is set, increment data is stored in the COUNT
flip-flop. At time state T2, the COUNT pulse is gated to the COL INC counter by CLK H. The
negative-going edge of the COUNT pulse clocks the counter.
The COL INC counter is a BCD counter which counts up if the COUNT pulses result from a positive
increment and down if they result from a negative increment. Overflow from the counter is stored in
the OVERFLOW flip-flop and gated to the SIGN and carry/borrow (C/B) flip-flops. At time state
TI, the OVERFLOW flip-flop is cleared by the 1.184 J.LS pulse from MPC5. At time state T2, the
OVERFLOW lip-flop is set by the OVERFLOW increment. At time state T3, the OVERFLOW pulse
is gated to the SIGN flip-flop and the C/B flip-flop by the 592 ns pulse.
This toggles the C/B flip-flop to indicate that an overflow occurred. lethe counter has just reached 9,
the SIGN flip-flop is set to a I and a BORROW H is sent to the MPC.lfthe counter has just reached
0, the SIGN flip-flop is set to 0 and a CARRY H is sent to the MPC. The C/B and SIGN flip-flops are
sampled by the MPC every 416 J.LS and the C/B flip-flop is retoggled by CLR C/B after each sample is
taken.
The CLR INIT command is issued by the MPC at the end of the IN IT routine to set the COL INC
counter to 5 and clear the C/B flip-flop.

COUNT F/I'".COUNT CLK
MPC 1

COLUMN R2 COUNT 2
INCREMENT COL INC
COUNTER RI COUNT I
ON
COL INC
RO COUNT 0

+ FIF + INC
MPC 1

BORROW H MUX I
MUX 2
MPC 4

R3t-:C:-:"O-L- : - I N : - : " C - - - - - - - - t

CG ROM
} MPC6

CARRY H MUX I
MPC4

LO
CLR
DEC I INIT L
MPC4

o
I0184 sec
CLOCK {
LOGIC
MPC5

CIB

OVERFLOW

CLR CIB
DEC I {
MPC4 CLR INIT L

'--------'

592nl
CP-1587

Figure 4-31

Column Increment Counter and C/B Generator Logic

4-46·

4.10 BELL SYSTEM
A simplified logic diagram of the bell system is shown in Figure 4-32. Initially, the BELL HOLD flipflop is cleared by WU from the wake-up circuit. When a bell is required, the BELL HOLD flip-flop is
set by a SET BELL pulse from the DECl. This gates a 2.4 kHz signal (208H) to the speaker via a
transistor switch, (QIO) to produce an audible tone. The MPC controls the duration of th.e tone, by
clocking the BELL HOLD flip-flop with the CLR BELL pulse at 100 ms intervals.
When the MPC is initialized or the print head passes the 132nd column, the KB HOLD flip-flop is set
by a CLR KBH L pulse from DEC I. Each time a character is shifted into the UART, the KB HOLD
flip-flop is clocked by EOC (end of character). When the print head passes the 64th column, the MPC
checks KBH. If it is set, the MPC sends a SET BELL pulse to the BELL HOLD flip-flop.
SPEAKER

DEC I ! on " "
MPC4

,1--------1

"
BELL

CLR BELL
HOLD
....::.:.:.:......=.:c:.:.....-Ic

WAKE UP -"W:.:...;.U::..:.._ _----'
MPC8
-CLOCK LOGIC -=2;.;;..08::..:.H'--_ _ _ _ _- '
MPC5
DECI MPC4 CLR KBH

o
KB
HOLD
~~~: ...;:Ec.:::.:0C"----_-IC
0

KBH MUX 1 MPC4
CP-1589

Figure 4-32

Bell System Logic

4.11 LINE FEED STEPPER SYSTEM
A simplified logic diagram of the line feed stepper system is shown in Figure 4-33.
Four STEP commands and a HOLD command are issued by the MPC when a line feed is required.
The STEP LF L command pulses are applied to the clock inputs of a grey code counter and to the data
input of the LF HOLD flip-flop. The SET HOLD L command pulse is applied to clear inputs of the
counter and the set input of the LF HOLD flip-flop.
PHASE 1

1/----'------'
-20
+20

GREY
CODE
COUNTER

STEP LF L

LF2 _ _--1
1 /--_--=.:c...::....
LF

PHASE 2

LF STEPPING
MOTOR

-20
DEC 1
MPC4

LF
HOLD

COMMON

LF
HOLD

SET HOLD
WAKE UP -"-'W'c.=;.U,-.---,L-..-'
MPC8

S
CP-1588

Figure 4-33

Line Feed Stepper System
4-47

The relationship of these pulses is shown in Figure 4-34. At power-up, WU sets the LF HOLD flipflop, causing the LF amplifiers and the LF HOLD amplifier to apply a holding current to both phases
of the LF stepping motor. WU also clears the counter.

STEP LF L

SET HOLD L

ILF HOLD L

-I-

23 MS
I

J
J

to MS--I

LFt H

1
1

LF2 H

I 5.0
I MS

I-

II
6.8
MS

7.5
MS

3.7
MS

33 MS

NOTE:

Not drawn to Icale.
CP- 1619

Figure 4-34

Line Feed Timing Diagram

When a line feed command sequence is issued by
the MPC, the LF HOLD flip-flop is reset and
the STEP LF pulses are decoded by the counter
as shown in the truth table in Table 4-8. The LF
HOLD, LFl, and LF2 amplifiers are turned on
and off accordingly. Each change causes the
stepping motor to advance 15 degrees, providing
four steps for each line advance and vertical
spacing of 2.36 lines/cm (6 lines/inch). A complete line advance takes 33 ms ± 5% nominal.

Table 4-8 LF Pulse Truth Table
LF2

LFI

Hold

Step LF

After the line advance is completed, another
SET HOLD pulse is sent by the MPC and the
LF HOLD flip-flop is set again. A 10 ms delay
(typical) between line feeds allows the stepping
motor to settle. The minimum settling time is 8.2
ms.

Step LF
Step LF

4.12 WAKE-UP (WU) CIRCUIT
The wake-up circuit is shown on MPC8. This circuit is a time-delayed transistor switch that generates a
700 ms WU pulse. The WU pulse initializes the MPC logic before the MPC starts to run. WU pulse
duration is dependent on the RC time constant of the resistor and capacitor across the +5 V power
supply. During power-up, the output transistor is turned on and WU is at logic level zero. After one
time constant (approximately 700 ms), the output transistor is turned off, WU goes to logic level one
and the MPC starts to run.
4-48

4.13 POWER SUPPLY AND REGULATOR
A block diagram of the power supply circuits is shown in Figure 4-35. The ac line voltage is stepped
down by a transformer, rectified, and filtered to produce +21 V, -21 V, and +5 V.
These voltages are regulated to produce +12 V %5 percent, -12 V %5 percent, +5 V %5 percent, and
-9 V %5 percent.
+21VDC

+12V
VOLTAGE
REGULATOR

BRIDGE

f---- RECTIFIER
AND
FILTER
AC
LINE

LINE
FI LTER

r --

poWER
ON/OFF

-12V
VOLTAGE
REGULATOR

+12VDC

lr -.

-12VDC

VOLTAGE
REGULATOR

STEP DOWN
TRANSFORMER

-9VDC

-21VDC

BRIDGE

r---- RECTIFIER
AND
FILTER

+5V
VOLTAGE
REGULATOR

+5VDC

CP-1SIIO

Figure 4-35

Power Supply Block Diagram

4.14 PRINTER MECHANISM
The LA36 is an incremental impact printer
that uses a 7-wire solenoid-activated print
head which moves horizontally and prints
characters in a 7 X 7 dot matrix. A fixed
print bar is impacted by pressure on an
inked ribbon traveling between the horizontally moving print head and the paper.
Figure 4-36 illustrates the printing principle
used in the LA36. Seven individually selectable solenoids are mounted in a cluster on
the print head assembly. The armatures of
the solenoids are fitted with long wires that
function as the printing element by impacting the inked ribbon against the paper.
Each printed character is inscribed by positioning the print head at seven discrete horizontal positions as it traverses the paper.
For each of the seven horizontal positions,
a combination of solenoids is activated to
produce a 7 X 7 dot image of the selected
character.

CP-1171

Figure 4-36

4-49

LA36 Printing Principle

The printer mechanism of the LA36 is made up of several functional subsystems: the carriage subsystem, the ribbon feed subsystem, and the paper feed subsystem.

4.14.1 Carriage Subsystem
The carriage subsystem (Figure 4-37) includes the print head and the carriage which ride on the two
support shafts that extend the full width of the printer mechanism. The carriage is driven by a timing
belt which is held captive between the print head and the carriage and runs on a pulley at each end. The
right-hand pulley is mounted on the dc servo motor, which provides the driving power for the carriage.
The left-hand pulley is mounted on the ribbon drive shaft and transmits power to the ribbon feed
subsystem.
The carriage supports and positions the print head relative to the print bar and provides for adjustment of the paper gap by means of a detented adjustment lever on the right side of the carriage. Each
detent position represents approximately 0.076 mm (0.003 inch) of gap and allows for a total of
approximately 0.51 mm (0.020 inch) of paper gap.

HEAD

PULLEY
1/5 PITCH
TIMING BELT

CP-1172

Figure 4-37

Carriage Subsystem

4.14.2 Ribbon Feed Subsystem
The ribbon feed subsystem (Figure 4-38) consists of a ribbon drive and a ribbon reversal mechanism.
The left-hand pulley, attached to the ribbon drive shaft, drives the ribbon feed through a one-way
clutch/eccentric, a push rod, and a ratchet/pawl mechanism. The one-way clutch allows for ribbon
feed during the printing cycle and inhibits feed during the carriage return cycle. A brake on the oneway clutch allows the eccentric to turn in one direction only. The eccentric on the ribbon drive shaft
translates rotary motion to linear motion and drives the ratchet/pawl by means of a pushrod. The
ratchet/pawl mechanism translates linear motion to the rotary motion required to turn the ribbon
reels. The main pawl and the upper pawls, due to their unique arrangement, alternately perform drive
and backlash functions, depending upon the direction in which the pushrod is traveling. When shifted
to the left or to the right by the rivet at the ends of the ribbon, the reverse sensor cams an interposer
into the path of the tab on the main pawl. The blocking action ofthe interposer and the pivoting action
of the ratchet base assembly shift the main pawl and engage the upper pawl in the opposite ratchet
wheel.
Ribbon reversal is accomplished by carriage motion rather than by ribbon motion. This eliminates the
possibility of carriage stalls due to excessive tension during the reversing action.
Constant ribbon tension is maintained by a friction disk on each ribbon reel.
4-50

BACKSTOP
SPRING

ECCENTRIC

PUSH ROD

REVERSE
SENSOR

RATCHET

INTERPOSER
BAIL CAMMING
FOLLOWERS

PAWL

CP-1175

Figure 4-38

Ribbon Feed Subsystem

4.14.3 Paper Feed Subsystem
The paper feed subsystem (Figure 4-39) includes
a stepping motor, a manual clutch, and two pinfed tractors.

15° STEPPING MOTOR
SQUARE
DRIVE SHAFT

The stepping motor connects to the tractors
through a 2:5 gear train and a square drive shaft.
The driven gear on the square shaft is fitted with
a manual clutch that uncouples the gear train
from the square shaft when the line feed knob is
axially depressed. This allows fine vertical
adjustments when preprinted forms are used.
CP -1173

Figure 4-39

4-51

Paper Feed Subsystem

The stepping motor executes four steps for each line advance to ensure that the tractors will always
initialize on an integral line when the machine is turned on.
The use of tractors permits flat surface feeding which eliminates interleaf slippage in multipart forms
and reduces hole distortion during paper feeding.

4-52

CHAPTER S
UPGRADED LA36

5.1 GENERAL
The purpose of this chapter is to reflect the equipment changes incurred since the original publication.
Changes of significant importance include:
1.
2.
3.
4.
5.
6.
7.

M7723 Logic Board
M7728 Logic Board
Power Board Changes
Constant Voltage Transformer
New Bezel
Caps Lock Keyboard
Addition of Options.

5.2 LA35/LA36 MODEL VARIATIONS
The variations and associated model numbers for the LA35/LA36 are listed below.
Model No.

Designation

Variation

LA35-CE
LA35-CF
LA35-CH
LA35-CJ
LA35-DE
LA35-DJ

LA35
LA35
LA35
LA35
LA35
LA35
LA35

90-132 V, 60 Hz
180-264 V, 60 Hz
90-132 V, 50 Hz
180-264 V, 50 Hz
90-132 V, 60 Hz
180-264 V, 50 Hz

LA36-CE
LA36-CF
LA36-CH
LA36-CJ
LA36-DE
LA36-DF
LA36-DH
LA36-DJ

LA36
LA36 with Numeric Pad and Paper Out
LA36 with Numeric Pad and Paper Out
LA36 with Numeric Pad and Paper Out
LA36 with Numeric Pad and Paper Out
LA36
LA36
LA36
LA36

90-132 V, 60 Hz
180-264 V, 60 Hz
90-132 V, 50 Hz
180-264 V, 50 Hz
90-132 V, 60 Hz
180-264 V, 60 Hz
90-132 V, 50 Hz
180-264 V, 50 Hz

5.3 EASY IDENTIFICATION OF LOGIC BOARDS
There are three possible logic board models that can be installed in a DECwriter: M7722, M7723, and
M7728. The M7722 board is typically factory installed in earlier LA36s while the M7723 and M7728
boards are found in newer terminals. The M7728 performs all functions of the M7722 and M7723 and
is backward compatible for a direct replacement for either board. Replacing either board with an
M7728 does not enhance the capabilities of the terminal in which the M7728 board is installed.

5-1

Figure 5-1 shows the obvious physical differences between the three logic boards that permit easy
identification. The M7722 and M7723 boards each have four connectors while the M7728 has five
connectors. The M7723 and M7728 boards have solder-dot test points around the perimeter and the
M7722 does not have these test points.
SOLDER DOTS
TEST POINTS

·.............. .
·
................
.
··•
·• ·•
·•
· •

M7722

M7723

LOG IC BOARD

M7728

•

•
•

LOGIC BOARD

•

............. ·................ ..
5

4 CONNECTORS

CONNECTORS
CP-2391

Figure 5-1

Physical Characteristics of M7722, M7723, and M7728 Logic Boards

5.3.1 Major Functional Differences Between M7722 and M7723 Logic Boards
There are three major functional differences between the M7722 and the M7723 logic boards.
I.

Local Copy Feature
M7722 - No local capability when terminal is operating on-line (sometimes called halfduplex mode).
M7723 - Has local copy feature. Three-position front panel rocker switch permits printing
when in local or on-line in half- or full-duplex mode.

Parity Selection
M7722 - No received parity capabilities. Only even or no parity selection on transmission.
No eighth bit spacing capability.
M7723 - Choice of even or odd parity for both receiving or transmitting.

Paper Out Option
M7722 - No provision for accepting the PAPER OUT switch.
M7723 - Compatible with PAPER OUT switch.

5.3.2 M7722, M7723, and M7728 Jumper Configurations
The M7722, M7723, and M7728 jumper configurations are described in Chapter 3.
5.3.3 Functional Differences Between M7723 and M7728 Logic Boards
In addition to having all the features of the M7723 board, the M7728 can also provide the data and
signal interface required when options are installed in an upgradable LA35/LA36. The M7728 has the
same possible transmit and receive parity configuration as the M7723. In addition, the received parity
error print indication (three vertical bars) can be suppressed in certain instances when the eighth level
bit is used as a control code for the options.
5-2

5.3.4 M7718 Cabling Configurations/Option Combinations
The possible cabling configurations for the M7728 logic board are shown in Figure 5-2.
CAUTION
The ribbon cables between the logic board and the
expander board must be installed so that one cable
end (either end) has the ribbed side of the cable facing up and the other end has the smooth side up.
Ensure that A connects to A at each cable end. Failure to observe this polarity may cause a logic board
failure.

TO J1
POWER BOARD
20mA SERIAL
I NPUT (IF USED)

M772B LOGIC BOARD

A. NO OPTIONS INSTALLED

.TO J1
POWER BOARD
20mASERIAL
INPUT (IF USED)

TO J2 FRONT

TO J2
KEYBOARD --+-----1-.......,

.-----+- PANEL CONTROL

BOARD (DIP CONNECTOR)

M772B
LOGIC BOARD
EXPANDER MOUNTING
OPTION (LAXX- LB)

B. ANY OPTION WITH THE FOLLOWING EXCEPTIONS:
AUTO LINE FEED OR AUTO ANSWER BACK OPTIONS NOT INSTALLED

TO J1
POWER BOARD
20mA SERIAL
INPUT (IF USED)

TO J2

FRONT

.-----1-- PANEL CONTROL
BOARD (DIP CONNECTOR)
M7728
LOGIC BOARD
EXPANDER MOUNTING
OPTION
(LAXX- .. B)

C. ANY OPTION AND
AUTO LINE FEED OR AUTO ANSWERBACK OPTIONS INSTALLED

C P-2102

Figure 5-2 Cabling Configurations for the M7728 Logic Board
5-3

5.4 MAJOR POWER SUPPLY CHANGES
There are four major changes to the power supply.
1.

The rating of the ac line fuse was increased from 2 A SB to 3 A SB for 115 V and from 1 A
SB to 1.5 A SB for 230 V.

The two 1 A SB fuses in the line feed motor drive circuit were replaced with four 3/4 A SB
fuses.

The 18,000 ~F capacitor in the capacitor bank was replaced with a 37000 ~F capacitor.

A constant voltage transformer (CVT) replaced the original transformer.

5.4.1 New Power Transformers
Upgradable LA35/LA36s have constant voltage power transformers installed to accommodate the
increased power requirements of the options. There is a unique transformer model for 50 Hz operation
and another model for 60 Hz operation. Both models function on either 115 or 220 Vac primary
voltage and provide ± 24 and + 11 Vdc at the secondary voltage.
5.5 NEW KEYBOARD BEZELS
The keyboard bezel associated with the upgradable LA36 is shown in Figure 5-3. There is no change in
the bezel for upgradable LA35s. The LA36 also has another bezel configuration that accepts the 14key Numeric Keypad Option which mounts to the right of the standard keyboard.
POWER

Off

."0.
ON

I-- ~oo, --+- BAUD RAn -I
IrlfE

toe.
ArT
CHAit

SET

FOX
N!H_

CHAR

srr

lOO

liO

JOO

AUTO
If

~fltf

ESt

(oJ

(SEll

u,
CAPS

iOC:o<

SHIFT

'-'TO
ALT
HARACTfR Sf!

PAPER
OUT

%
5

SELL

)

SA.CK

SPAct

"
K

&
7

,,:M~

RI','"''

ClE',--t-:1

Fa,:

8l1i ~,

SHin

RPU'

DrvlCE. 5Et[(!
SEtEC1 AVAil

7622-28

Figure 5-3

LA36 Keyboard Bezel

5.6 CAPS LOCK KEYBOARD
The caps lock keyboard has a CAPS LOCK key substituted for the SHIFT LOCK key normally found
on office equipment. When the CAPS LOCK is depressed, the 26-letter keys transmit only uppercase
codes; all other keys print in lowercase.
5.7 LA35jLA36 OPTIONS
All options listed in Tables 1-8 and 1-9 can be installed in a LA35/LA36 DECwriter except for the 14Key Numeric Keypad and the Paper Out Options.
5.8 DECwriter II - M7728 FUNCTIONAL DESCRIPTION
The following LA35/LA36 printers are designated as option-upgradable DECwriters.
LA36 Manufactured in U.S.A. - Serial numbers 02-21933 and higher
LA36 Manufactured in Ireland - Serial numbers 04-10450 and higher
LA35 Manufactured in U.S.A. - Serial numbers 5001 and higher
These printers have the increased power supply capability and the M7728 logic board required to
accommodate the various available options.
5-4

The basic block diagram for the M7728 logic Bbard is shown in Figure 5-4. The major difference
between this diagram and tM diagrams for the M7723 boards is in the data conversion block. All other
functional areas operate in the same manner as in the other boards. The three items added to the data
conversion are:
1.
2.
3.

Expander Board
Options
Tri-State Buffer.

SET/CLR

BEL

2.4 KHi

BELL
SYSTEM

J LINE
FEED
STEPPER

LF/LF HOLD

t-----"----.:'---="'----......
-I
MIRCRO-

I
I

SYSTEM

CRYSTAL 't-_---:..:1...:::68::,;9:..:6;:.:;M;:.:.H:,.Z---i PROGRAMMED
CLOCK,
CONTROLLER I---....::C::::A::.:;RR~Y:..:./...!:B~O::.:;RR~O::..:W=-I::..:N=:CR~E:.::M:.=E:.:.NT-=----,

(MPCI
SPEED DATA
DATA BUS

....
II"

I
SERIAL
INPUT

RECEIVE
LOOP

Jt - - - - - ,

'I- - {RIBBON
DRIVE

(/)
:;)

--- ,
DATA
COMMUNICATIONS
INTERFACE

L....-~~~....---.....,
CHARACTER
ADDRESS

CARRIAGE
SERVO
SYSTEM

SYSTEM

I
I

rOAn I CONVERSION

I
II

I
I
I
I

ADDRESS
REGISTER

I
-------11 TR~~~~IT 14-+L _ _ ...J I A

UART

TRI-STATE
BUFFER

CHARACTER
BUFFER

CHARACTER
GENERATOR

PRINT HEAD
SYSTEM

DOT MATRIX

II"

L.._ _ _- - - '

t---..,..-_......--''--_ _--'-_ _ _--'-_R_O_M_-i-+----,

EXPANDER BOARD

I
I

OPTIONS

I
I

COLUMN INCREMENT COUNT

L0~<3

KEY
STROBE

(/)

KEYBOARD
SYSTEM

I
cp- 2333

Figure 5-4 Basic Block Diagram of M7728 Logic Board
5-5

The data conversion block still performs its basic function of taking serial-in (SI) ASCII data and
converting it to a 7 X 7 dot pattern that drives the print head. Transmitted keyboard data is converted
to serial-out (SO) ASCII data by the data conversion block. These functions do not change in an
upgradable printer; only now, certain options exercise control over both the receive and transmit data
lines by blocking, inserting, or allowing data to pass.
The control logic for the M7728 board is shown in Figure 5-5. As stated previously, there is no
difference in the operation, configuration, or programming of the Microprogrammed Controller
(MPC). New identification numbers are assigned to the components and their physical location on the
circuit board are changed, but the basic function of each remains the same. The new numbers and
schematic sheet locations are noted on Figure 5-5.
The major area of change affects the receive and transmit data paths.
5.8.1 New Transmit Path
Keyboard data now passes through the expander board before it is applied to the transmit section of
the UART. As this data is routed across the expander board, two switching methods are employed to
ensure that installed options can break this data path and insert characters into the transmit data. This
keyboard steering is shown in Figure 5-6. Hardware steering is accomplished by physically moving the
cable to the UART between connectors 11 and J2 on the expander board. When inserted in J2, keyboard data and the keystroke is routed right across the expander board without any interruptions.
When the Automatic Answerback Option or the Automatic Line Feed Option is installed, the cable is
moved to Jl and the data path is now through these options. There is a logic switch in these options
that allows the options to break the keyboard data path and insert either an answerback message or a
line feed command. After inserting the option-generated characters and keystrokes, the logic switch
allows keyboard data to pass out to the UART again.
5.8.2 New Receive Path
On the M7728 board, received data and parity error are routed through the UART to the tri-state
buffer rather than right to the character buffer as on the M7722 and M7723 boards. This tri-state
buffer permits the options to sample the UART output data before the character buffer receives it. The
options monitor the incoming data on the bidirectional line and can insert data on this line to be
applied to the character buffer. The output of the character buffer can be sampled by an Optional
Character Set Option which can substitute a new dot matrix pattern for the pattern normally generated
for this character by the character generator ROM.
5.8.3 Transmit Operation with Options Installed
Options that insert data into the keyboard data path between the keyboard and the transmit section of
the U AR T require a timing control signal to ensure that the U ART is ready to accept more data. This
control signal is the XMIT RDY L signal which is a high level when the UART is not ready to accept
another character and is low when another character can be processed. This signal is used to stroke
both the option-generated character and keystroke out of the option. The XMIT RDY L signal associated with the last character generated by the option causes the logic switch to revert back to the normal
position and allow keyboard data to pass again.

5-6

HI-+----~ ~~~~:~~
REGISTER
E9,Eli
(MPC3 )

512X8
CONTROL
ROM
E15
(MPC3)

SET BELL
CLR BELL
STEP LF - - - - ,

2.4 KHz

SET LF HOLD

LOAD CB.
ADDRESS

3 BIT COLUMN INCREMENT COUNT

PNTABL

SET HDE------,

CLR DA

SERIAL
OUTPUT

UART
E55(MPCS) 7 BIT ASC II
(REC)

SERIAL
INPUT
XMT
ROY L

EXPANDER BOARD AND OPTIONS

OPTIONAL CHARACTER SET
CR

OPTION CLOCK

CLR DA

BELL

DA
CP-2334

Figure 5-5

M7728 Control Logic Diagram

5-7

r-SERIAL

OUT

UART

I
I
I

M7728

LOGIC
BOARD

XMIT
+-=-~ SECTION

KEYSTROBE

------------- - -

- - - ---1
I
I

EXPANDER
OPTION
MOUNTING
BOARD

AUTO LINE FEED
LINE
FEED
CONTROL
LINE

ICEYBOARD

KEY
........-~BOARD

DATA

I
I
IL _ _

ANSWER
BACK
MESSAGE
GENERAtOR
ANSWER
BACK
OONTROL

AUTO ANSWERBACK

CP-2335

Figure 5-6 Steering of Keyboard Data

5.8.4 Receive Operation with Options Installed
Figure 5-7 shows the signals and components that affect the receive operation. After the U ART converts incoming serial data into even parallel bits, it places these bits on the data lines to the tri-state
buffer. Normally, as the UART is ready to output data, the data available (DA) line goes to a low
level. The microprocessor uses this low level to load the seven bits into the character buffer. In the
M7728 board, this DA signal is applied serially through all receive options before it is sent to the
microprocessor.

5-8

At each option the DA signal initiates an option-decoding function on the character present on the
bidirectional lines from the tri-state buffer. If the character is a command or code that is not recognized by the first option, the DA signal is passed along to the next option to be used to decode the
character at that option.
After being routed through all options to the microprocessor, the character is loaded into the character
buffer through the tri-state buffer. The remaining processes to the print head are the same as in the
M7722 and M7723 boards.
If the character present at the output ofthe UART is decoded by an option, this option blocks the data
through the tri-state buffer (using the UART ENAB signal). The option then places a character on the
bidirectional lines to the character buffer and issues the DA signal to the microprocessor. As before,
the microprocessor commands the character buffer to load, but now the character loaded is taken from
the option, not from the UART through the tri-state buffer.
After processing a character, the microprocessor issues the clear data available (CLR DA) signal
which causes the UART to place the next incoming character on the lines to the tri-state buffer. If an
option is going to insert more than one character (as when performing a top-of-form operation), the
option holds the tri-state buffer disabled, places another character on the bidirectional line, and issues
another option-generated DA signal. This action continues until the option has finished inserting
characters. The CLR DA signal associated with the last character inserted enables the tri-state buffer
and received data now passes through in a normal manner.

r----

-}
(

M7728 LOGIC BOARD
UART

SERIAL
IN

RECEIVE
SECTION

7 BITS

1---,/
t----,
DA

I
TRI-SllITE UART DATA BITS 1-7
BUFFER

TO
CHARACTER
GENERATOR
ROM

BUFFER

CLR
DA

MICROCONTROLLER

L...
B1-DIRECTIONAL
LINES

r;X;;E;;T;;-

CLR
DA

MOUNTING BOARD
DATA AVAILABLE

AU OPTIONS
IN RECEIVE
PATH

OPTION
DA

CLEAR DATA AVAILABLE

L __ _

Cp-2D;

Figure 5-7

Receive Operations of M7728 Logic Board

5-9

CHAPTER 6
ELECTRICAL SERVICING

6.1 ELECTRICAL TESTS
The test equipment required for the electrical tests is listed in Table 6-1. Equivalent test equipment may
be substituted. Two kinds of tests are provided: off-line and on-line. No diagnostics are required to
perform these tests. No waveforms are provided for the microprogrammed controller (MPC) section
of the logic board because special test equipment is required for accurate measurement and interpretation. Theoretical timing data and program descriptions are provided in Chapters 4 and 5. All
measurements are dc-coupled and referenced to ground unless otherwise stated. VOLTS/DIV setting
applies to both Channel 1 and Channel 2 unless otherwise stated.
Table 6-1

Test Equipment and Special Tools

Equipment

Manufacturer

Designation

Multimeter

Triplett or Simpson

Model 630 NA or 620

Oscilloscope

Tektronix

Type 454 (or equivalent)

IC Clip

A.P., Inc.

24-pin DEC Part No. 29-19556
16-pin DEC Part No. 29-10246

XIO Probe

Tektronix

P 6010 (or equivalent)

Slip-on-Tip

Tektronix

013-0090-00 (or equivalent)

EZHook

Pomona Electronic

3925 (or equivalent)

Resistor

30 to 50 n, 10 W minimum

Resistor

1000 n, 1/4 W minimum

6.1.1 Off-Line Tests
The off-line tests provide a means of obtaining test data in a stand-alone mode. All tests are performed
with the LINE/LOC switch set to LOC and the BAUD RATE switch set to 110.
NOTE
This note applies to printers with cover interlocks.
The cover interlock must be overridden to perform
the following tests. One method of overriding the
interlock is to temporarily tape the interlock switch
down.

6-1

Remove the printer housing from the LA36 as directed in Paragraph 7.2; lower the rear access door
before performing any off-line tests.
6.1.1.1 Encoder Signal Processing Test - The encoder signal processing test checks the open loop
operation of the threshold detectors, encoder signal detector, and the + / - TACH in the carriage servo
system using test voltages to drive the servo motor.
NOTE
The current limiting resistor shown in the test setup
diagrams (Figures 6-1 and 6-2) can be omitted, but
caution should be exercised to prevent damage.
To check the circuits that drive the motor in the positive direction, perform steps 1-6; to check the
circuits that drive the motor in the negative direction, perform steps 7-9.
NOTE
The voltages and time periods in the carriage servo
system vary for different machines, line voltages, and
value of current limiting test resistor. The values
listed in Figures 6-3 through 6-12 are nominal and
can be used as a guide.
1. Set the POWER switch to OFF.

2. While moving the print head toward the dc motor, slip the drive belt from the pulley on the
motor shaft.
3. At the servo fuse (F2), pull off the lead going to the power board (Figure 6-1).
CAUTION
1. Power board damage may result if the test voltage

is connected improperly in step 4.
2. Lead must not touch frame.
3. Remove fuse F1 from power board.
4. Apply +21 V to the servo motor by connecting the jumpers and the resistor between RI04
(bottom lead) and the servo fuse F2 (Figure 6-1).
5. Set the POWER switch to ON. The motor should rotate in the positive direction (clockwise
as viewed from the front of the LA36).
6. Check the waveforms at the test points shown in Figures 6-3 through 6-9.
7. Set the POWER switch to OFF and connect -21 V (R105 bottom lead) to the motor as
shown in Figure 6-2.
8. Repeat step 5. The motor should rotate in the negative direction (counterclockwise).
9. Check the waveforms at the test points shown in Figures 6-10 through 6-14.
NOTE
When reinstalling drive belt, ensure that left side
plate spring is in place.
6-2

10. Turn POWER switch to OFF. Disconnect the test setup and reinstall the drive belt and the
lead to the servo fuse (F2).
11. Reinstall fuse Fl on the power board, and set the POWER switch to ON.

30-60 OHM
10WMIN

Physical Connection

SER\Q FUSE
MOTOR

F2
"'"

JUMPER

Rl04

JUMPER

30-500HM
10 W MIN
TEST
RESISTOR

+21 V

CP- 2207

b.
Figure 6-1

Electrical Connection
Encoder +21 V Test Setup
6-3

30-600HM
10WMIN

POWER BOARD

SERVO FUSE

F1 (REMOVED DURING TEST)

MOTOR

Physical Connection

SEfM) FUSE
F.2o.~J~U=M~P=ER~-¥~~J~U~M~P~E~R. .__~R~10~5__-e
I----JV"\(;Yv
-21V
30-500HM
10W MIN
TEST
RESISTOR
CP-2206

Electrical Connection

Figure 6-2 Encoder -21 V Test Setup

6-4

START OF ENCODER SIGNAL PROCESSING TEST WAVEFORMS

Start of Positive-Direction Encoder Tests

SCOPE SETUP

t±
I-t-

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

VARIABLEAPPROX.
76 jaI/DIV

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC.
INT. POS

4.6 VDC

GNoL

CH 1 to + PT1 at power board J4-6
CH2 to + PT2 at power board J4-6
M·0674

Figure 6-3

+PTI and +PT2 Waveforms

SCOPE SETUP

::oL
4VI

GND

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

20 jaI

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC.
POS.INT

CH1 to +PT1 at:

M7722 E6-S
M7723 E2-S
M772S E1S-S

CH2 to +PT2 at:

M7722 E6-6
M7723 E2-6
M772S E1S-6

M-0668

Figure 6-4

+ PT 1 and + PT2 Schmitt Waveforms

6-5

+INC MAY OCCUR
ANYWHERE DURING
THIS TIME

SCOPE SETUP
VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

600ns

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC.
INT. POS

CH1 to -INC at:

M7722 E8-9
M7723 E7-9
M7728 E60-9

CH2 to COUNT at:

M7722 E4-9
M7723 E13-9
M7728E45-9

M-0677

Figure 6-5

+INC and COUNT Flip-Flop Waveforms

SCOPE SETUP

----1.184 !lS ---001
VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

200ns

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1. AC.
INT.POS

CH1 to COUNT F/F at:

M7722 E4-9
M7723 E13-9
M7728 E46-9

CH2 to COUNT pul.. at:

M7722 E29-8
M7723 E18-8
M7728 E49-3

GND--

GND _

NOTE:
50 ns pulse (CH2) may vary in response to COUNT pul.. (CH1).

Figure 6-6 COUNT Flip-Flop and COUNT Pulse Waveforms

6-6

,...._--1.184 J.I.S---.~I

3.9

SCOPE SETUP

GND

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

200ns

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC.
INT.POS

CH1 to COUNT F/F et:

M7722 E4-9
M7723 E13-9
M7728 E46-9

CH2 to CLR +/-F/F et:

M7722 E9-8
M7723 E3-8
M7728 E49-8

GND

NOTE:
118.4 joIS verie. with the speed of the encoder motor.

Figure 6-7

COUNT Flip-Flop and CLR ± Flip-Flop Waveforms

SCOPE SETUP

3.8

GND

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

20J.l.S

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1. AC. INT. POS

CH1 to +INC et:

M7722 E8-9
M7723 E7-9
M7728 E60-9

M·0671

NOTE:
118.4

J.I.S veri.. with the speed of the encoder motor.
Figure 6-8

+INC Waveform

6-7

SCOPE SETUP
VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:
TRIG MODE:

NORMAL

TRIG SOURCE:

CH1. AC.INT. NEG

CH1 to +TACH at:

M7722Q11-C
M7723Q11-C
M7728 c:i11-C

\iND-

Figure 6-9

+TACH Waveform

End of Positive-Direction Encoder Tests

Start of Negative-Direction Encoder Tests

SCOPE SETUP

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

VARIABLEAPPROX.
100 !lS

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC.
INT. POS

4.5 VDC

GNDL

CH1 to PT1 at power board J4-5
CH2 to PT2 at power board J4-6
M·0673

Figure 6-10 -PTI and -PT2 Waveforms

6-8

SCOPE SETUP

GND--

GND-

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TlME/DIV:

10 jaI

TRIG SOURCE:

CH1. AC. POS. INT

CH1 to -PT1 at:

M7722 U-S
M7723 E2-S
M772S E1S-S

CH2 to -PT2 at:

M7722 E8-8
M7723 E2-8
M772S E1S-8

M-0675

Figure 6-11

-PTI and -PT2 Schmitt Waveforms

SCOPE SETUP

-INC MAY OCCUR
ANYWHERE DURING

GND _ _
COUNT F/F MAY

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

&OOn.

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC.
INT.POS

CH1 to -INC at:

M7722 ES-6
M7723 E7-6
M732S E&O-6

CH2 to COUNT at:

M7722 E4-9
M7723 E13-9
M772SE46-9

GND--

M-0676

Figure 6-12 -INC and COUNT Flip-Flop Waveforms

6-9

SCOPE SETUP

r118.4IlS-\

GND-_

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

20 I'S

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC.
INT. POS
M7722 E8-5
M7723 E7-5
M7728 ESO-5

CH1 to -INC at:

M-067S

NOTE:
118.4 /J.s varies with the speed of the encoder motor.

Figure 6-13 -INC Waveform

SCOPE SETUP
VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

SO/J.s

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.DC.
INT. NEG

CH1 to-TACH at:

M7722Q12-C
M7723 Q12-C
M7728 Q12-C

GND--

t'lgure b-14 -TACH Waveform

End of Negative-Direction Encoder Tests

END OF ENCODER SIGNAL PROCESSING TEST WAVEFORMS

6-10

6.1.1.2 Servo Speed Test - The servo speed test checks the closed loop operation of the servo amplifier, sum amplifier, summing network, and column increment counter in the carriage servo system in
the initialize mode. To check the negative feedback logic and the carry/borrow logic, perform steps
1-4. The motor runs in reverse at a speed of 15.24 cm/second (6 inches/second). To check the positive
feedback logic and the carry/borrow generator, perform steps 1-3 and steps 5 and 6. The motor runs
forward at a speed of 15.24 cm/second (6 inches/second).

Set the POWER switch to OFF, and set the LINE/LOC switch to LOC.

While moving the print head toward the dc motor, slip the drive belt from the pulley on the
motor shaft.

Set the POWER switch to ON.

Check the waveforms at the test points indicated in Figures 6-15 through 6-22.

Jumper the base ofQ3 to ground. This causes the servo motor to reverse direction and run at
15.24 cm/second (6 inches/second).

Check the waveforms at the test points as indicated in Figures 6-23 through 6-28.
NOTE
Voltages and time periods in the carriage servo system vary for different machines and line voltages.
The values listed in Figures 6-15 through 6-22 are
nominal and can only be used as troubleshooting
guides.

Set POWER switch to OFF. Reinstall the drive belt and remove the jumper from the base of
Q3.

Set POWER switch to ON.
NOTE
Printers with PAPER OUT switches must be loaded
with paper in order to run the following tests:
LF Stepping Test
Bell Test
Printable Character Test
To prevent wasting paper, do not feed the paper
through the tractors during the line feed stepping
test.

6-11

START OF SERVO SPEED TEST WAVEFORMS

Start of Negative Speed Tests
SCOPE SETUP
VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

10!lS

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1, AC, POS,INT

CH1 to INC at:

M7722 E5-9
M7723 E12-9
M7729 E64-9

GND-

M7722 E6-11
M7723 E12-11
M7728 E64-11

CH2 to 76 !lS
CLOCK at:

Figure 6-15 -INC and 761ls CLOCK Waveforms
SCOPE SETUP

1.5 V ::J::'

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

10 ItS

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,
POS,INT

GND

9VI

CH1 to TACH at Q12-B on logic board

0.8 V

CH2 to TACH at Q12-C on logic board

NOTE:
Turn power off when connecting scope leads.

Figure 6-16 -TACH Waveforms at QI2-B and QI2-C
6-12

SCOPE SETUP

GND--

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

10p.s

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1. AC. POS.INT

CH1 to -TACH at:

M7722 E5-5
M7723 E12-5
M7728 E54-5

CH2 to 71 /l-S at:

M7722 E5-3
M7723 E12-3
M7728 E54-3

GND-

M-0681

Figure 6-17 -TACH and 76ILs Waveforms

71/1-S --.\........\ - - - - -

1.5V
GND

~ 1.3 rns

SCOPE SETUP

aNDI

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

200p.s

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC. POS.INT

CH1 to -TACH at:

M7722 Q12-B
M7723Q12-B
M7728 Q12-B

CH2 to SUM at:

M7722 J 1-B 11 -II
M7723J1-B IE1-11
M7728J1-B IE27-11

-5V

M-0682

Figure 6-18 -TACH and SUM Waveforms at J1-B

6-13

! - 1 .3ms

76 ItS

-t t-

SCOPE SETUP

1.6 V..,GND...L

VOLTS/DIV:

CH1 =2 V
CH2=6V

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

GNDI

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC. POS.INT

CH1 to -TACH at:

M7722012-8
M7723 012-8
M7728 012-8

-6V

CH2 to MD at power board J4-8
M-0683

Figure 6-19 -TACH and MD Waveforms

SCOPE SETUP

VOLTS/DIV:

VERTICAL MODE:

CH1

HORIZ DISPLAY:

TlME/DIV:

60ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC.
NEG.INT

CH1 to INC at:

M7722 E30-9
M7723 E22-9
M7728 E44-9

430ms

, I"

lI-

'-~

I" " I ....
II

:
M-0725

NOTE:

Waveform is flashing on and off scope.

Figure 6-20

INC Waveform

6-14

- - \ 3ms

SCOPE SETUP

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TlME/DIV:

2ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,
POS,INT

GND-

CH1 to COL INC
COUNT (MSB) at:

M7722 E16-7
M7723 E16-7
M7728 E43-7

CH2 to COL INC
COUNT 2 at:

M7722 E16-6
M7723 E16-6
M7728 E43-6

GND--

Figure 6-21

COL INC COUNT 3 (MSB) and COL INC COUNT 2 Waveforms

SCOPE SETUP

GND--

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

6ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,INT, POS

CH1 to COL INC
COUNT :f (MSB) at:

M7722 E16-7
M7723 E16-7
M7728 E43-7

GND-CH2 to BORROW Hat:

~1·~-----30ms----~·~1
Figure 6-22

M7722 E12-3
M7723 E10-6
M7728 E16-11

M-0685

COL INC COUNT 3 (MSB) and BORROW H Waveforms

End of Negative Speed Tests
6-15

Start of Positive Speed Tests

SCOPE SETUP
VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TlME/DIV:

10 ItS

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1. AC. POS. INT

CHl to +INC at:

M7722 E3-9
M7723 E17-9
M7728 E40-9

GND--

GNDCH2 to -76 /LS
CLOCK at:

Figure 6-23

78 itS

+INC and 76 /-LS Waveforms

SCOPE SETUP

GND--

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TlME/DIV:

10/LS

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1. AC. POS.INT

CHl to +TACH at:

M7722 E3-6
M7723 E17-6
M7728 E40-6

CH2 to 78 itS at:

M7722 E3-3
M7723 E17-3
M7728 E40-3

GND--

M-0688

Figure 6-24

M7722 E3-11
M7723 E17-11
M7728 E40-11

+TACH and 76 /-LS Waveforms

6-16

SCOPE SETUP

76 ILS

1.5 V::r.

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

10 ILS

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC,
POS,INT

CH1 to +TACH at:

M7722 Q11-B
M7723 Q11-B
M7728 Q11-B

CH2 to +TACH at:

M7722 Q11-C
M7723 Q11-C
M7728 Q11-C

.::T
Figure 6-25

1.3
76 ILS

+TACH Waveforms at QII-B and QII-C

ms---1l

SCOPE SETUP

GNo-......

GND--

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

200 IlS

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1, AC, pas, INT

CH1 to +TACH at:

M7722 Q11-B
M7723 Q11-B
M7728 Q11-B

CH2 to SUM at:

M7722 J1-B IE1-6)
M7726 J1-B IE1-6)
M7728 J 1-B IE27-6)

M-0690

Figure 6-26

+TACH and SUM Waveforms

6-17

r;-1.3ms

761'5-1i--

-I

SCOPE SETUP

GND--

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

600

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC. POS.INT

CH1 to +TACH at:

M7722011-B
M7723011-B
M7228011-B

GND--

1'5

CH2 to MD at powar board J4-B

M·0691

Figure 6-27

+TACH and MD Waveforms

SCOPE SETUP

4VI
GND

.::r

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

6ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1. AC. POS. INT

CH1 to COL INC
COUNT 3 (MSB)at:

M7722 E16-7
M7723 E16-7
M7228 E43-7

CH2 to CARRY Hat:

M7722 E7-6
M7723 E10-8
M7728 E16-8

M-0692

Figure 6-28 COL INC COUNT 3 (MSB) and CARRY H Waveforms

End of Positive Speed Tests

END OF SERVO SPEED TEST WAVEFORMS

6-18

6.1.1.3 Line Feed (LF) Stepping Test - This test causes the LF stepping motor to run continuously. It
generates signals to test the Grey Code Counter, both channels of the amplifier, and the LF HOLD
circuit.
1.

Set POWER switch to ON, and LINE/LOC switch to LOC.

Press the LF key and the REPEAT key at the same time to get a sequenCe of line feeds.

Check the waveforms (with keys depressed) at the test points shown in Figures 6-29 through
6-35.

START OF LF STEPPING TEST WAVEFORMS

t41.--23 ~

SCOPE SETUP

+21 ±

6VI
6V

20V

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

6ma

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC.NEG.INT

CH1 to PHASE 1 at power board J6-7

GND -21 ±

VOLTS/DIV:

CH2 to PHASE 2 at power board J6-6

Figure 6-29

LF Motor Phase 1 and Phase 2 Waveforms

6-19

SCOPE SETUP

21 ± 6V

GND

21 ± 6V

VOLTS/DIV:

20V

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

6ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1. AC. pos. INT

CH1 to LF1 at power board Q34-C

GND

CH2 to LF2 at power board Q36-C

I I 7'~13'7

~
ms

6.8
ms

Figure 6-30

M-0694

23 ms

LFI Waveform at TPA12 and LF2 Waveform at TPA15

SCOPE SETUP

GND
-21 V ± 6 V

GNDI

VOLTS/DIV:

20V

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

6ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC.
POS.INT

CH1 to LF1 at power board Q36-C

-21 V ± 6 v

CH2 to LF2 at power board Q37-C

Figure 6-31

LFI Waveform at TPA13 and LF2 Waveform at TPA16

6-20

SCOPE SETUP

5V
0.6 V

5VI
0.6 V

VOLTS/DIV:

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

5ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1, AC, NEG, INT

CH1 to LF1 at power board 039-C
CH2 to LF2 at power board 038-C

.o 1 6.8

1 7.5 13 .7
ms

M·0696

23ms_

Figure 6-32

LFI Waveform at TPA14 and LF2 Waveform at TPA17

SCOPE SETUP
VOLTS/DIV:

CH1=20V
CH2=2 V

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TlME/DIV:

5ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1, AC, NEG, INT

GND _ _

GND--

CH1 to LF motor common return at
power board J5-4
CH2 to LF HOLD at power board J1-29 (033-B)

Figure 6-33

LF Motor Common Return and LF HOLD Waveforms

6-21

SCOPE SETUP

GND_

GND-

.o \
~
ms

6.8 \ 7~5
\3.7
ms
ms
ms
23 ms

VOLTS/DIV:

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

5ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1. AC. POS. INT

CH1 to LF1 at:

M7722 E24-9
M7723 E8-10
M7728 E28-10

CH2 to LF2 at:

M7722 E24-5
M7723 E8-8
M7728 E28-8

M-0698

Figure 6-34 LFI Waveform at Jl-JJ and LF2 Waveform at Jl-P

SCOPE SETUP

GND _ _·

VOLTS/DIV:

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

5ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1. AC. pos. INT

CH1 to LF1 at:

M7722 E24-9
M7723 E8-10
M7728 E28-1 0

CH2 to LF HOLD at:

M7722 E29-6
M7723 E5-5
M7728 E37-5

GND--

M-0699

Figure 6-35

LFI Waveform and LF HOLD Waveforms

END OF LF STEPPING TEST WAVEFORMS

6-22

6.1.1.4 Bell Test - This test drives the bell system logic, providing the signals required to trace the
circuit.
1.

Set POWER switch to ON, and LINE/LOC switch to LOC.

Hold down the CTRL key and press the BELL key and the REPEAT key.
NOTE
CTRL and REPEAT keys can be taped down with
scotch tape. Do not use masking tape; it will mar the
surface.

Check the waveforms (with keys depressed) at the test points indicated in Figures 6-36 and

6-37.
NOTE
Voltage measurements at JS-2 are taken with WI jumper inserted.

Press the RETURN and REPEAT keys and check the waveforms at the test points indicated
in Figure 6-38.

START OF BELL TEST WAVEFORMS

1-418p.1

-I

SCOPE SETUP

GND-

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

100p.1

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC. NEG.INT

CH1 to BELL lource et power board J6-1
CH2 to BELL SINK at power board J6-2

GND-

Figure 6-36

BELL Source and BELL SINK Waveforms
6-23

108 ms
BURST

SCOPE SETUP

5V' - r -

418 /lS
PERIOD

'-'--

VOLTS/DIV:

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

20ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC.
POS.INT

GND

I.
fT

III

CH1 to BELL SINK at powar board J&-1
CH2 to BEL at:

GND

....

Figure 6-37

106 ms

108 ms

B4ms-l

M7722 E38-&
M7723 E14-6
M772B E34-&

-I

Mon6

BELL SINK and BELL Waveforms

SCOPE SETUP

18ms

.::r

VOLTS/DIV:

VERTICAL MODE:

CH1

HORIZ DISPLAY:

TIME/DIV:

20ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1. AC. POS.INT

CH1 to KBH Hat:

M7722 E61-8
M7723 E22-8
M7728E30-8

M-0701

NOTE:
This is a difficult waveshape to observe.

Figure 6-38

KBH H Pulse Waveform

END OF BELL TEST WAVEFORMS

6-24

6.1.1.S Printable Character Test - This test checks the operation of the printer logic in the local
mode. Various printing characters are used to provide test data that can be easily interpreted. The"/"
(slash) character generates a single dot in each column. The "u" and ... " characters generate complementary ASCII codes that test every bit on the lines between the keyboard, the UART, the character buffer, and the CG ROM.
1.

Press the "\" (slash) key and the REPEAT key to get a series of printing characters that
have one dot in every column.

Check the waveforms (while depressing the keys) at the test points listed in Figures 6-39
through 6-49.

Momentarily press the SHIFT key and U key (simultaneously). Check test point 1 in Table
6-2 for the correct level.

Momentarily press the SHIFT key and ... " key (simultaneously). Check test point 1 in
Table 6-2 for the correct level.

Repeat steps 3 and 4 for test points 2 through 7.

Momentarily press the SHIFT key and U key (simultaneously). Check test point 1 in Table
6-3 for the correct level.

Momentarily press the SHIFT key and "." key (simultaneously). Check test point 1 in
Table 6-3 for the correct level.

Repeat steps 6 and 7 for test points 2 through 7.
Table 6-2 UART Test
Character

Test Point

1.
2.
3.
4.
5.
6.
7.

M7722

M7723

M7728

E55-26, E56-4
E55-27, E56-6
E55-28, E56-10
E55-29, E56-12
E55-30, E57-4
E55-31, E57-6
E55-32, E57-10

E58-26, E59-4
E58-27, E59-6
E58-28, E59-10
E58-29, E59
E58-30, E60-4
E58-31, E60-8
E58-32, E60-10

E55-26, E41-4
E55-27, E41-6
E55-28, E41-10
E55-29, E41-12
E55-30, E36-4
E55-31, E36-6
E55-32, E36-10

1
0
1
0
1
0
1

0
1
0
1
0
1
0

Table 6-3 Character Buffer Test

M7722

M7723

M7728

Character
U

E28-18
E28-17
E28-16
E28-15
E28-14
E28-13
E28-22

E45-18
E45-17
E45-16
E45-15
E45-14
E45-13
E45-22

E48-18
E45-17
E45-16
E45-15
E45-14
E45-13
E48-22

0
1
0
1
0
1
0

Test Points

1.
2.
3.
4.
5.
6.
7.

6-25

•
1
0
1
0
1
0
1

START OF PRINTABLE CHARAcrER TEST WAVEFORMS

'""1.--- #J.8----,~1

SCOPE SETUP

800

4VI
GND

+20Vl

sov

ov -

-20 V

NOTE:
Pin numbers are merked on J8.

VOLTS/DIV:

CH1=2V;
CH2=20V

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

100 ItS

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC.
NEG.INT

CH1 to HD EN et power boerd
J1-4.022-8
CH2 to SOL 1-S0L7 et power
board J8 pins B. 12.4. 10
18. 8. or 4 1_ notel
IQ17-C. Q19-C. Q1-C. Q20-C.
Q1B-C. Q18-C. or Q21-CI

Figure 6-39 HO EN and SOL Waveforms at J6

SCOPE SETUP

GNOr

VOLTS/DIV:

CH1=2V
CH2=6V

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

4.BV

TIME/DIV:

1 ms

..l

TRIG MODE:

TRIG SOURCE:

CH2.AC.
POS.INT

CH2

CH1

23V

GND

CH1 to HS1-HS7 at:

2.6 V

M7722 E26-4. E26-8. E20-4
E20-8. E20-B. E26-B. E20-10
M7723 E2B-4. E2B-8. E26-4
E26-8. E26-B. E2B-B. E26-10

M·0703
NOTE:
Q38 hes been chenged to as on REV T power boerd.

M772B E47-1. E47-4. E47-10
E47-13. E82-1. E82-4. R82-10
CH2 to SD1-SD7 et power boerd:

Figure 6-40 HSI and SOl Waveforms
6-26

Q8-E. Q14-E. O2-E. Q3B-E 1_ notel.
Q12-E. Q4-E. end Q12-E

SCOPE SETUP
VOLTS/DIV:

CH1=2V
CH2=6V

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

1 ms

TRIG MODE:

TRIG SOURCE:

CH2V.
AC.POS.INT

4.SV

lCH1
GND

CH1 to HS1-HS7 at:
M7722 E26-4. E26-6. E20-4
E20-6. E20-S. E26-S. E20-10
M7723 E2S-4. E2S-6. E26-4. E26-6
E26-S. E2S-S. E26-10
M-0704

M772S E47-1. E47·4. E47-10. E47-13
E62-1. E62·4. E62-10

NOTES:
1.

038 has been changed to OS on REV T power board.

Channel 2 test points are difficult to reach with most probes.

Figure 6-41

CH2 to SD1-SD7 at power board:
06-8.014-8.02-8.038-8 (see notes).
012-8. 04-8. and 010-8

HS 1 and SD 1 Waveforms
SCOPE SETUP

VOLTS/DIV:

CH1=2V
CH2=10V

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

1 ms

TRIG MODE:

TRIG SOURCE:

CH2. AC.
POS.INT

4.SV

~GND
GNDT
~

-24 V

CH1 to HS1-HS7 at:

M7722 E25-4. E26-6. E20-4
E20-6. E20-S. E26-S. E20-10
M7723 E2S-4. E2S-6. E26-4. E26-6
E25-S. E2S-S. E26-10
M-0705

M772S E47-1. E47-4. E47-10. E47-13
E62-1. E62·4. E52-10
CH2 to SD1-SD7 at power board:
07-C. 016·C. 03-C. 09·C.
013-C. 06-C. and 011-C

Figure 6-42

HS1 and SD1 Waveforms
6-27

SCOPE SETUP
VOLTS/DIV:

CH1=2V
CH2=10V

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

1 ms

TRIG MODE:

GNDI

TRIG SOURCE:

CH2.AC.
NEG.INT

-22 V

CH1 to HS1-HS7 at:

IV
4.

GND

M7722 E26-4. E26-8. E20-4.
E20-8. E20-1. E26-1. E26-10

M-0706

NOTE:
031 has been changad to 01 on REV T power board.

M7723 E21-4. E21-8. E26-4. E28-8
E26-1. E21-1. E26-10
M7721 E47-1. E47-4. E47-10. E47-13
E62-1. E62-4. E62-10
CH2 to SD1-SD7 at power board:
08-C. 014-C. 02-C. 038-C (see notel.
012-C. as-C. and 010-C

Figure 6-43

HSI and SDI Waveforms

6-28

SCOPE SETUP

GND-

VOLTS/DIV:

VERTICAL MODE:

CHOP

IIJ

HORIZ DISPLAY:

TIME/DIV:

6ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH2. NEG.INT

CH1 to HD EN at:

M7722 E39-8.
M7723 E18-8
M7728 E39-8

...0
UI

GND_

HS1

CH2 to HS1-HS7 at:
M7722 E26-4. E26-6. E20-4.
E20-8. E20-8. E26-8. E20-10

....

M7723 E28-4. E28-8. E26-4. E28-8
E26-8. E28-8. E26-10

GND-

M7728 E47-1. E47-4. E47-10. E47-13
E62-1. E62-4. E62-10

...

Pulsa moves one position to the right

IIJ

for e,ch new measurement: HS1-HS7.

GND_

HS7
M-070B

Figure 6-44 HD EN and HS 1 Waveforms at J1

6-29

SCOPE SETUP

VOLTS/DIV:

CH1=2V
CH2=6V

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

6ma

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC.
NEG.INT

GND

5VI
GND

M7722 E39-8
M7723 E18-6
M7723 E39-6

CH1 to HD EN
at J1 (R68):

CH2 to BUFF HEAD EN H at power board Q22-C
M-0707

Figure 6-45

HD EN and BUFF HEAD EN H Waveforms

SCOPE SETUP
VOLTS/DIV:

CH1 =2 VDC COUPLED
CH2=1 VAC COUPLED

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

2001'8

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1. AC. POS. INT

GND-

WARNING
Float scope power line before
making these connections.
M-0709

CH1 to HD EN at:

M7722 E39-9
M7723 E36-9
M7723 E37-9

CH2 to SD1-SD7 at power board R62.
R53.R1. R54.R56. R51.R66
CH2 probe ground to -21 V

Figure 6-46

HD EN Voltage Waveform and SD Current Waveform

6-30

NOTE:
Scope intensity may have to be turned up to make
this waveshape visible.

Figure 6-47

WRITE BUFF Land CLR R DONE Waveforms

SCOPE SETUP

GND

VOLTS/DIV;

VERTICAL MODE:

CH1

HORIZ DISPLAY:

TIME/DIV:

SOOns

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC. NEG.INT

CH1 to KEY ST8 at:

M7722 E87-4
M7723 E60-12
M7728 E68-2

M-0711

NOTES:
1. Scope intensity may have to be turned up to
make this wavashape visibla.
2. This pulse is 500 ns wide on aerlierkeyboards.

Figure 6-48

KEY STB L Waveform

6-31

SCOPE SETUP
VOLTS/DIV:

1 VAC COUPLED

VERTICAL MODE:

CH1

HORIZ DISPLAY:

TIME/DIV:

20ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC. POS.INT

CH1 to power board 026·E

M·0712
NOTE:
M key was pressed to produce this waveshape.

Figure 6-49

Power Board V REF Waveform

END OF PRINTABLE CHARACTER TEST WAVEFORMS

6.1.1.6 Clock Test - The clock test checks all clock frequencies and time periods in the initialize
mode.
1.

Set the POWER switch to ON.
..
Check the waveforms at the test points indicated in Figures 6-50 through 6-58.
START OF CLOCK TEST WAVEFORMS
SCOPE8ETUP

GND-

VOLTSiDIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

200ns

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1. AC. POS. INT

CH1 to 692 ns at:

M7722 EM·10
M7723 E34·10
M7728 E19·10

CH2 to CLK Hat:

M7722 EM·6
M7723 EM·6
M7728E19·6

GND-

M·0713

Figure 6-50 CLK Hand 592 ns Waveforms
6-32

SCOPE SETUP

GND -

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

200ns

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1.AC.NEG.INT

CH1 to 1.184/Ls at:

M7722 E13-1
M7723 E21-1
M7128 E19-10

CH2 to 592 ns at:

M7122 E13-14
M7723 E21-14
M7128 E66-12

GND -

M-0714

Figure 6-51

592 ns and 1.184 #LS Waveforms

SCOPE SETUP
VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

GND--

TRIG MODE:

NORMAL

TRIG SOURCE

CH1.AC.NEG.INT

CH1 to 9.4/Ls at:

M7122 E26-1
M7123 E30-1
M7128 E68-1

CH2 to 76 /LS at:

M7722 E26-11
M7123 E30-11
M7728 E68-11

GND-

Figure 6-52

9.4 #LS and 76 #LS Waveforms

6-33

SCOPE SETUP

GND--

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

2/lS

TRIG MODE:

NORMAL

TRIG SOURCE

CH1. AC. NEG.INT

CH1 to 9.4 /lS at:

M7722 E26-1
M7723 E30-1
M7728 E68-1

CH2 to 19L at:

M7722 E26-9
M7723 E30-9
M7728 E68-1

GND--

M-0716

Figure 6-53

-I

18.8 /ls

9.4 IlS and 19L IlS Waveforms

I-

SCOPE SETUP
VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TlME/DIV:

GND-

TRIG MODE:

NORMAL

TRIG SOURCE

CH1.AC.NEG.INT

CH 1 to 18.8 /lS at:

M7722 E28-9
M7723 E30-9
M7728 E88-9

CH2 to 78 /lS at:

M7722 E26-11
M7723 E30-11
M7728 E68-11

GND-

\,....- - - - - - 7 8 /lS - - - -...,~\

Figure 6-54

M·0717

18.8 IlS and 76 IlS Waveforms

6-34

SCOPE SETUP
-11_18.8 its

GND-

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

20 itS

TRIG MODE:

NORMAL

TRIG SOURCE

CH1. AC. POS. INT

CH 1 to 18.8 itS at:

M7722 E26-9
M7723 E26-9
M7728 E68-9

CH2 to 4.8 kHz at:

M7722 E63-11
M7723 E48-11
M7728 E63-11

GND-

Figure 6-55

I·

416 its

18.8 J.Ls and 4.8 kHz Waveforms

SCOPE SETUP

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

60 ItS

TRIG MODE:

NORMAL

TRIG SOURCE

CH1. AC. POS. INT

CH1 to208H:

M7722 E26-12
M7723 E30-12
M7728 E68-12

CH2 to 4.8 kHz at:

M7722 E63-11
M7723 E48-11
M7728 E63-11

GND -

GND-

M·071S

Figure 6-56

208 Hand 4.8 kHz Waveforms

6-35

SCOPE SETUP

GND-

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

200ns

TRIG MODE:

NORMAL

TRIG SOURCE

CH1. AC. POS. INT

CH1 to 529 ma at M7728 E81-10
CH2 to option clock at M7728 E81-8

GND_

M-0721

Figure 6-58

M7728 Option Clock Waveform

END OF CLOCK TEST WAVEFORMS

6-36

6.1.2 On-Line Tests
The on-line tests provide a means of obtaining test data in a simulated on-line mode. All tests are
performed with the LINE/LOC switch set to LINE. Remove the protective housing from the LA36 as
directed in Chapter 7, and lower the rear access door before performing anyon-line tests:
6.1.2.1 Current Loop Interface UART and Character Buffer Test - The current loop interface test
checks the operation of the 20 rnA current loops (transmit and receive) for the standard configuration.
On-line operation is simulated by connecting the transmit and receive loops back-to-back through a
current limiting resistor. The UART test checks the output of the UART. The buffer test checks the
single character buffers and the AND gates between the buffer and UART.
1. Set the POWER switch to OFF.
2. Connect the transmit and receive loops back-to-back as shown in Figure 6-59.
3. Set the POWER switch to ON.
4. Set the BAUD RATE switch to 300.
Current Loop Test
5. Simultaneously press and hold the SHIFT, "*", and REPEAT keys while observing the
waveforms at the test points listed in Figures 6-60 through 6-61.
UART /Single Character Buffer Test
6. Momentarily press the SHIFT key and "*,, keys (simultaneously). Check test point 1 in
Table 6-2 for the correct level.
7. Momentarily press the SHIFT key and "*,, key (simultaneously). Check test point 1 in
Table 6-2 for the correct level.
8.

Repeat steps 6 and 7 for test points 2 through 7.

9. Momentarily press the SHIFT key and U key (simultaneously). Check test point 1 in Table
6-3 for the correct level.

10. Momentarily press the SHIFT key and "*,, key (simultaneously). Check test point 1 in
Table 6-3 for the correct level.
11. Repeat steps 9 and 10 for test poins 2 through 7.
12. Check the frequency at the appropriate logic module (M7722 - E55-40, M7723 - E58-40,
M7728 - E55-40) for each baud rate.
Position

Frequency

300
150
110

4.8 kHz
2.4 kHz
1.76 kHz

The time periods should be the same as the corresponding clock logic signals (Figures 6-55 and 6-56).

6-37

START OF CURRENT LOOP INTERFACE WAVEFORMS

~---------------II

LOGIC BOARD
I M7728

I
I 11 r ~ ~ ~ 1\ [\==I] [\==I] [ '
J3

1U t

100b"OHM
1/4 WATT

"-JUMPER

CJ 1~ T ~ 1\ I
tIll
_

~---------------,

I ~~~1~2~~~~~3
I

II c:----rJ \ei i i i i i
I
U t
I
7

2,\

CJ \e

iii

100'b"OHM

'---JUMPER

114 WATT

I
1 \ I
i
I
I

L______~JUM':'U::M~::K-=:_ J
PHYSICAL CONNECTION

20 MA LOOP

J4
7

1000 OHM
1/4 WATT

-12V---r~~----~~------~O-r------

20 MA

+12V---r~~--------------~O-r------

ELECTRICAL CONNECTION
CP-t606

Figure 6-59 Current Loop Test Setup

6-38

I
I

SCOPE SETUP

GND_

VOLTS/DIV:

CH1 =2 VDC COUPLED
CH2=1 VAC COUPLED

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

6ms

TRIG MODE:

NORMAL

TRIG SOURCE

CH1. AC. POS. INT

CH1 to SI at:

M7722 E62-1
M7723 E62-1
M7728 E60-4

GND_
CH2 to receive at logic board J3-3
M-0722

NOTE:
Mark = GND; Spaca = 6 Vor 1.6 V.

Figure 6-60

Loop Receiver Waveforms

SCOPE SETUP

GND-

VOLTS/DIV:

CH 1 =2 VDC COUPLED
CH2=1 VAC COUPLED

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

6ms

TRIG MODE:

NORMAL

TRIG SOURCE

CH1.AC. NEG.INT

CH1 to SO at:

M7722 E68-11
M7723 E62-11
M7728 E61-11

GND-

CH2 to transmit at logic board J3-6
M-0723

NOTE:
Mark = GND; Spaca = 6 Vor 1.6 V.

Figure 6-61

Loop Driver Waveforms

END OF CURRENT LOOP INTERFACE WAVEFORMS

6-39

6.1.2.2 Serial Line Interface - The serial line interface test checks the operation of the serial input
(EIA) and serial output (EIA) and mode selection logic for the standard configuration. On-line operation is simulated by connecting the transmit and receive logic back-to-back through a jumper.
1. Set the POWER switch to OFF.

2. Connect the transmit and receive loops back-to-back as shown in Figure 6-62.
3. Set the POWER switch to ON.
4. Set the BAUD RATE switch to 300.
5. Simultaneously press the SHIFT key, ..... key, and REPEAT key to get a series of printing
characters.
6. Check the waveforms at the test points listed in Figure 6-63.
7. Momentarily press the SHIFT key and U key (simultaneously). Check test point 1 in Table
6-2 for the correct level.
8. Momentarily press the SHIFT key and U key (simultaneously). Check test point 1 in Table
6-2 for the correct level.
9. Repeat steps 7 and 8 for test points 2 through 7.
10. Momentarily press the SHIFT key and ... " key (simultaneously). Check test point 1 in
Table 6-3 for the correct level.
11. Momentarily press the SHIFT key and ... " key (simultaneously). Check test point 1 in

Table 6-3 for the correct level.
12. Repeat steps 10 and 11 for test points 2 through 7.

6-40

START OF SERIAL LINE.INTERFACE WAVEFORMS

'LOGICBoARO-------------,

I M7722, M7723, M7728
\

I
l

.12

.14

8
I

4
I

2 1\
I I

YUMPER

I
I
I
I
I

~~~~~~~~-~~~-~~~
PHYSICAL CONNECTION

.14

Sol.
JUMPER
SoOo

ELECTRICAL CONNECTION
CP-1623

Figure 6-62 Serial Line Test Setup
SCOPE SETUP

GND-

VOLTS/DIV:

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

6mB

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1. AC. POS.INT

CH1 to SO lit:

M7722 E29-12
M7723 E18-12
M7728 E80-12

CH2toSI lit:

M7722 E66-6
M7723 E63-2
M7728 E42-11

GND-

M-0725

NOTE:
6 V = SPACE: GND = MARK

Figure 6-63

Serial Output and Serial Input Waveforms

END OF SERIAL LINE INTERFACE WAVEFORMS

6-41

6.1.3 Wake-Up Test
This test checks the wake-up pulse upon initialization of the LA36.
NOTE
The scope probes must be connected to the test points
specified in Figure 6-64 prior to applying power.

Set the POWER switch to ON, and observe Figure 6-64.

SCOPE SETUP

VOLTS/DIV:

VERTICAL MODE:

AL T

SWEEP:

SINGLE SWEEP

TIMEIDIV:

100ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC, EXT,POS

CH1 to Wake-Up at: M7722 E38-1
M7723 E14-1
M7728 E34-1
(See note 2.)

GND

Notes:
1. This waveform is a dot moving across the scope.
Upon power application the dot is a logic zero,
it then goas to a logic one when wakeup is completed.

2. The transformer secondary power board IJ3-41 we.
used to trigger the scope.
M-Q558

Figure 6-64 Wake-Up Waveform

6-42

6.2 TROUBLESHOOTING CHARTS (ON-LINE TESTS)
The troubleshooting chart in Table 6-4 lists the common trouble symptoms that could be observed
during installation checkout or during normal operation of the LA36. The sequence of these
indications is important and the steps must be performed in the order presented. Read through symptoms I-II in Table 6-4, and perform the troubleshooting related to the selected symptom. If no symptom is given with the machine servicing request, perform the installation checkout procedure in
Paragraph 2.5 to determine the status of the machine. This procedure and the troubleshooting chart
are cross-referenced to aid in diagnosing problems. Appropriate paragraphs and figures in this manual
are referenced to provide additional information needed to isolate defective components and realign,
adjust, or replace assemblies. Field-replaceable assemblies are the printer mechanism, print head, logic
board, and power board. (Chassis-mounted parts are also replaceable.)
NOTE
Steps 1 through 3 can be used to troubleshoot the
LA35.

6-43

Table 6-4 Troubleshooting Chart
Symptom

Problem Area

Probable Cause

Action

1. No response when POWER switch
is set to ON (fan not operating, no
lights).

Main printer power fuse

Blown

Unplug printer. Check Fl
(3A Slo Blo at 115 V or
1.5 A Slo Blo at 230 V).
Replace.

POWER switch

Switch failure

Replace S1.

Power harness

Poor connections

Unplug printer,
check harness.

Voltage jumper
connected to 11

Not plugged in or
loose

Check harness and jumper.

Servo fuse F2 (front of
printer). Early printers,
check Fl, 2A SB on
power board.

Blown

Turn off printer. Check
servo fuse F2 (2 A
Slo Blo).

Power transformer

Open winding

Check voltage.

Power board

Loss of low voltage

Check +12 V, -12 V, +5 V,
+21 V, and -21 V

Servo fuse

Servo fuse F2 (front
of printer). Early
printer, check F 1
on power board.

Check fuse and replace
(2 A Slo Blo).

2. a. No response when POWER
switch is set to ON (fan
operating).

b. Print head does not move.

6-44

Reference

Table 6-5

Table 64 Troubleshooting Chart (Cont)
Symptom

Problem Area

Probable Cause

Action

Reference

2. b. Cont

Logic board, power board,
carriage, or encoder motor

Faulty speed circuit on
logic board, open on
power board, jammed
carriage, or inoperative
motor

Connect probe to l1-B
(sum output) on logic
board. Set PRINTER
switch (power) OFF then
ON and observe voltage.

Speed circuits,
Paragraph 6.1.1.2

~
_ _ (-10 VI

YES

t_h.... (+10VI

Ic_.

hult ....
C _ ....... clrcult.

1. on
~faro_i
_ _ ...
ar

--.
_f_

2. ~ far fIoulty

3. C _ f a r _
jom.

3. Carriage moves violently or
erratically from margin-to-margin
or goes to either margin and
stays there.
NOTE
If print head moves violently, remove
the servo fuse prior to checking de
voltages (logic board), clock pulses,
and servo amp (power board).

MPC portion of logic
board

Replace logic board.

Power board

Loss of low voltage

Check +12 V, -12 V, +5 V,
+21 V, and -21 V.

Table 6-5

Logic board

Loss of clock signals

Perform clock test.

Paragraph 6.1.1.6

No wake-up

Perform wake-up test.

Encoder out of
adjustment.

Perform encoder
adjustment.

Encoder

Paragraph 8.2

6-45

Table 64 Troubleshooting Chart (Cont)
,

Symptom

Problem Area

Probable Cause

Action

Reference

3. Cont

Logic Board

Encoder processing

Perform encoder signal
processing test.

Paragraph 6.1.1.1
NOTE
To obtain negative and
positive drive waveforms,
perform setup described
in Paragraph 6.1.1.2.

Servo amp

Check waveshapes and
servo amp circuits on
power board schematic.

Negative drive, Figure 6-19
Positive drive, Figures 6-26
and 6-27 Power board
schematic sheets

Paper

Paper jammed/feed
holes torn

Check paper alignment.

Paragraph 3.4

Line feed motor

Line feed fuses,
motor or tractor drive
shafts and tractor
assemblies binding

a. Press in and turn Paper
Advance knob to check
for tractor and tractor
shaft binding.

Chapter 7, tractor and
tractor shaft replacement
procedure

b. Turn Paper Advance
knob to check for
motor and idler gear
binding

Chapter 7, stepping motor
replacement procedure

Keyboard

Press space bar. No
response when space bar
is depressed. Check and
replace keyboard or
keyboard cable. If printer
responds, continue with
troubleshooting chart.

Paragraph 6.1.1.5

LF motor fuses blown

Check F2 and F3, or F2 and
F5 as applicable to power
board.

Power board

I
!
I

4. No line feed when LINE FEED key
is pressed (printer is in local mode ).
NOTE
Keyboard does not work when
printer is out of paper.

Keyboard

Power board

I,
I
I
,

6-46

Table 6-4 Troubleshooting Chart (Cont)·

Symptom

Problem Area

Probable Cause

I Action

Reference

Perform line feed stepping
test and check:

Paragraph 6.1.1.3

LFI at Q34-C and
LF2 at Q36-C

Figure 6-30

LFI at Q35-C and
LF2 at Q37-C

Figure 6-31

LFI at Q39-C and
LF2 at Q38-C.

Figure 6-32

LF HOLD switch
signals missing.

LF HOLD at Q33-C and
LF MOTOR COMMON
at Q33-B

Figure 6-33

Grey Code Counter
output missing

Perform line feed stepping
test and check:

Paragraph 6.1.1.3

LFI at M7728, E31-8 and
LF2 at M7728, E31-6.

Figure 6-36

LF HOLD flip-flop
output missing

LFI
LF HOLD

Figure 6-35

Tractors

Not feeding-worn or
broken pin or out of
alignment

Check, align, or replace.

Chapter 7

Shafts

Binding

Check, align, or replace.

Chapter 7

Clutch

Binding broken

Check~ align, or replace.

Chapter 7

Gears

Broken teeth,
insufficient or
excessive backlash

Check, align, or replace.

Chapter 7

Amplifier output signals
missing

4. Cont

Logic board

i
I

6-47

Table 6-4 Troubleshooting Chart (Cont)
Symptom

Problem Area

Probable Cause

Action

5. No bell tone when erRL and BELL
keys are pressed.

Loudspeaker

Open voice coil

Check for approximately
2.4 kHz at speaker Faston.
If signal is present, replace
speaker.

Power board

Resistor or +5 V

Check and correct.

Logic board

BELL HOLD flip-flop
M7722, E36; M7723,
E14; M7728, E34

Perform bell test and check: Paragraph 6.1.1.4

6. No printout when ''\'' (slash)
key is pressed; head does not
move (LINE/lOC switch in LOC).

Reference

BEL SOURCE at J 5-1 and
BEL SINK at J5-2

Figure 6-36

BEL SINK at J5-2 and
BEL at M7722, E36-5;
M7723, E14-5;
M7728, E34-5

Figure 6-37

208 H at M7722, E26-12;
M7723, E30-12;
M7728, E68-12.

Figure 6-56

KB HOLD flip-flop E51

Check KBH-H at
M7722, E51-8;
M7723, E22-6;
M7728, E30-6 for a high
(KBH must be high for any
printable character).

Figure 6-38

Keyboard

CTRL and Bell keys

Check keyboard keys

Logic board

PNTABL HI signal

Check the following:

Paragraph 6.1.1.5

M7722, E25-10
M7723, E44-8
M7728, E61-6

PNTABL H = Approximately +4 V
PNTABL = Approximately 0.8 V

6-48

Table 6-4 Troubleshooting Chart (Cont)
Symptom

Problem Area

Probable Cause

Action

Reference

7. No printout when "\" (slash)
key is pressed. However, carriage
moves across carriage bar and head
solenoids sound as if they are ftring.

Carriage

Carriage Adjustment
lever is not set correctly.

Perform impression
adjustment.

Paragraph 3.4.2

Ribbon

Replace ribbon.

Paragraph 3.5

Ribbon assembly, ribbon
feed does not reverse
or feed.

Out of adjustment

Check and adjust.

Chapter 8

Paper path not clear

Check and clear.

Chapter 8

Phase adjustment

Check and adjust.

Figure 7·28

Print head

Head alignment

Align head.

Chapter 8

Print head assembly

Print head cable.

Replace print head.

Chapter 7

Broken print head boar

Replace print head.

Chapter 7

Power fault

Check +21 V and -21 V
at power board circuit
RI04 and RI05. Replace
appropriate components
or power board.

Voltage reference

Check Q25-E.

NOTE
Ribbon runs out of
ink due to repeated
printing on the same
portion of the n'bbon.

8. Print head does not ftre when
pressing "\" key. However,
carriage moves across carriage bar.

Power board

Figure 6-49

NOTE
Head will not fire
if V reference
equals -21 V.

6-49

Table 6-4 Troubleshooting Chart (Cont)
Symptom

Problem Area

Probable Cause

Action

8. Cont

Power board or logic
board

HDE signal

Perform printable
character test and
observe waveforms

Logic board

MPC

Replace logic board.

Power board

No solenoid drive
signals for missing
row

Perform printing character
test and check Sl-S7
at appropriate pin on J6
while printing. Check
appropriate test points
in drive amplifier for
that row.

No head select signals
for missing row

Check HSI-HS7 at
appropriate points on
power board.

No head select signals
for missing row

Check HS1-HS7 at
appropriate points on
logic board.

9. Missing dots when "\" key is pressed
(always same row) (all printable
characters that use the missing
row)

Logic board

Failed head select
drivers or bad cable
between logic board
and power board

Print head

(always same row, same letters)

Logic board

Reference

Perform printable character
test, Paragraph 6.1.1.5.

Perform printable character
test, paragraph 6.1.1.5.

NOTE
If missing at this point,
indicates that bit is
missing in CG ROM
output.

Stuck or broken impact Power down and up. Retry,
wire
if condition exists, let it
run. If condition does not
clear, check the following
before replacing head:
Open Solenoid winding

Check winding

Print head cable

Check print head cable

CGROM

Replace logic board.

Paragraph 7.3

Figure 6-66

Paragraph 7.24

6-50

Table 6-4 Troubleshooting Chart (Cont)
Symptom
10.

11.

Printer stops prior to
completing a printed
line

Printer operates in local but not
on-line mode.

Problem Area

Probable Cause

Action

Reference

Printer mechanism

Printer mechanism out
of alignment

Perform printer mechanism
adjustment procedure.

Chapter 8

Power board

Servo fuse F 1 blown

Check, determine the
following causes before
replacing fuse:

Ribbon mechanism
jammed near end of
ribbon

Check, adjust, or replace.

Paragraph 7.7

Carriage binding on
poorly adjusted carriage
shafts

Check, align, or replace.

Paragraph 7.5

Broken timing belt

Replace.

Paragraph 7.4

Timing belt off pulley

Check and correct. Replace
belt if worn or frayed.

Paragraph 7.4

Interface or interface
connectors

Connection problem

Check connectors.

Logic board (in current
loop operation)

Improper jumpers on
current loop converters

Check, correct.

Chapter 2

Failure in isolator
circuits

Perform current loop
interface test and check:

Paragraph 6.1.2.1

S.1.

Figure 6-60

S.O.

Figure 6-61

TRANSMIT at 13-5.
LINE/LOCAL switch

Switch shorted to
LOCAL condition

Check, replace.

(In EIA operation or
option)

Failure in gating logic

Perform serial line
interface test and check:

Paragraph 6.1.2.2

S. O. at E29-12

Figure 6-63

S. l. at E66-6.

Figure 6-63

6-51

Table 6-4 Troubleshooting Chart (Cont)
Symptom

Problem Area

Probable Cause

Action

Reference

12. Loss of position (Figure 6-65)
when printing multiple lines.

Power supply

+5 V supply

Check +5 V supply for
ripple or spikes.

Table 6-5
Figure 6-67

Encoder

Dust on encoder
disc

Carefully clean off
encoder disc

Paragraph 8-2

Replace logic board.

Chapter 7

Logic board

13. Uneven print density across

Print bar

Out of adjustment

Check and adjust

Paragraph 8.5

Power board

V reference

Check Q25-E

Figure 649

Print bar

Pitted

Replace.

Chapter 7

Carriage rods

Out of adjustment

Check and adjust

Chapter 8

Ribbon drive assembly

Out of adjustment

Check and adjust.

Chapter 8

Bad drive clutch

Repair or replace

Chapter 7

Broken backstop
spring

Replace.

Chapter 7

Print head

Out of adjustment

Check and adjust.

Chapter 7

Ribbon feed does not
reverse or feed

Broken ratchet tooth

Replace ratchet wheel

Chapter 7

Push rod disengaged

Correct

Chapter 7

Interposer adjustment

Adjust.

Chapter 7

Out of adjustment

Check and adjust.

Chapter 8

Paper path not clear

Check and adjust

Chapter 8

Phase adjustment

Check and adjust.

Chapter 7

Bad batch of paper

Replace paper

the page.

Printing light in areas

Printing density progressively
drops off to no impressions.

Ribbon does not reverse

Paper jams

Tractors

Paper
,,

6-52

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• •• XI' ( ) *+. -.10123456789: ; <-=>1@A9CDEF'GHIJKLHNOr-QRSTUVWXYZ(\J- _ 'abcdefghiJlo:.llflnoF'orstu .... wx~z{:}.... !' •• XI' ( ) *+, --.10123456789: ; <=>'?IABCD
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' •• XI' (
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'.'XI' () *+, - ,10123456789: ; <=)?@ABCDEFGHIJKLHNOPORSTUVWXYZ[\]- .• abcdeof!lhiJkl .. noporstullwx!:lz{:}.... !' •• XI' ( )*+, - .10123456799: ; <=>?@ABCD
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>.,. •

Figure 6-65

Example of Lost Position (reduced 50 percent)

6-53

The microprogrammed controller (MPC) section of the logic board is not listed as a probable cause
because it is quite difficult to field test this section correctly without special test equipment. Replace
the logic board whenever an MPC fault is suspected.
Check all fuses and power supply voltages before beginning to troubleshoot. Fuse locations are shown
in the Illustrated Parts Breakdown (Appendix B). Power supply voltages are shown in Table 6-5 and in
Figure 6-67. Voltage measurements are referenced to ground unless otherwise indicated.
Table 6-5

DC Supply Voltages

Voltage

Tolerance
(Volts)

Power Board
Test Points

Current
(Amps)

+5
+12
-12
+21
-24
-21
-24

±0.25
±0.6
±0.6
±5
±2
±5
±2

+ 5 V terminal
11-3 (CI6+)
11-19 (ClS-)
RI04 Bottom
RI04 Bottom
RI05 Bottom
RI05 Bottom

2.0
0.2
0.17
5.0

(See note)
(See note)

5.0

NOTE
21 V supply is 24 V on all printers with a constant
voltage transformer.

NOTE:
Print head shown on bottom view.
CP-1706

Figure 6-66 Print Head Solenoid
Resistance Measurement

6-54

+12V

050

R99
3.9K

069
RI03
I !SO 0

RI02
6190

<:TID

CI5
O.Oll'f

C!E::>

048

QE:>
071
5.IV

R90
2700

CI6
251'f

R92
4870

~
R90
2700

072
5.IV

R93
4870

GE:>

<:::ili:>+

046

GE:>

CI3
.Oll'f
R95
3900

R94
3.9K

R98
619A

C~-IO'D

1---

CI8
251'f

R97
150

070
049

-12V

<8IE:>
051

C[E::>

+5V

+8.5 TO
+13.5V
CI7
251'f

C8
19O1'f

.,..
CP-1381

Figure 6-67 Typical Voltages for Power Supply Regulators

6-55

CHAPTER 7
MECHANICAL SERVICING

7.1 GENERAL
This chapter contains information pertaining to the removal, replacement, and adjustment of the
mechanical subassemblies of the LA36/LA35.
NOTE
The procedures for servicing the LA36 can be used to
service the LA3S.
Figure 7-1 lists all the removal procedures in this chapter and the sequence in which these procedures
are performed. As an example, Figure 7-1 illustrates that to remove the timing belt, the printer housing
and print head removal procedures must be performed first.
DEC Field Service recommends that the following LA36 assemblies be replaced in their entirety in a
field environment.
1.
2.
3.
4.
5.
6.

Print Head Assembly
Printer Mechanism Assembly
DC Motor and Encoder Assembly
Tractor Assemblies
Ribbon Drive Assembly
Ribbon Chassis Assembly

7.2 PRINTER HOUSING
The following procedure describes the removal and installation of the printer housing.
7.2.1

Printer Housing Removal
1.

Remove power from the printer by disconnecting the ac plug.

Remove the printer paper and printer cover.

. Remove the eight (6-18) screws and flat washers that secure the printer housing to the cabinet base (Figure 7-2) and set them aside.

7-1

PRINTER
HOUSING
7.2

I
RIBBON DRIVE
ASSEMBLY
7.7

PRINT
HEAD
7.3

LOGIC
BOARD
7.24

POWER
BOARD
7.23

I
TRACTOR
DRIVE SHAFTS
AND TRACTOR
ASSEMBLIES
7.14

RIBBON DRIVE
PULLEY
7.10

BAR

TRANSFORMER
ASSEMBLY

7.17

7.20

I
TIMING
BELT
7.4

PRINTER
MECHANISM
7.13

RIBBON
DRIVE FAFNIR
BEARING
7.8

RIBBON
CHASSIS
ASSEMBLY
7.15

IDLER GEAR
ASSEMBLY
7.18

RIBBON SPOOL
RACHET WHEELS
AND FRICTION
DISKS
7.16

STEPPING
MOTOR
ASSEMBLY
7.19

LINE FILTER
ASSEMBLY
AND LINE
FUSE HOLDER
7.21

I
CARRIAGE
SHAFTS AND
CARRIAGE
ASSEMBLY
7.5

RIBBON
ECCENTRIC
WITH CLUTCH
7.9

KEYBOARD
ASSEMBLY
7.23

CP-3008

CARRIAGE
BUSHINGS
AND CARRIAGE
LEVER
7.6

Figure 7-1

DC MOTOR
AND ENCODER
ASSEMBLY
7.12

Assembly Removal
Sequence
7-2

2 (6-18) SCREWS
( HIDDEN)

2 (6 -18) SCREWS
(HIDDEN)

2 (6-18) SCREWS

CP-Hi59

Figure 7-2 Printer Housing Removal

7-3

J1CONNECTOR

LOGIC BOARD

J2 CONNECTOR

J1 CONNECTOR

J5 CONNECTOR

J2 CONNECTOR

•• • • • • • • • • • • • • • • • • • • • ••

: ~u~u:
•
•
•
•
•
•
•
•
•

•
•
•
•
•
M7723
•
LOGIC BOARD
•
•
• • • • • • • • • • • • • ••
J2

M7722
LOGIC BOARD

SOLDER DOTS
TEST POINTS

CP-3012

Figure 7-3

Power Board Connectors

7-4

7.2.2 Printer Housing Installation
1.

Place the printer housing on the cabinet base and secure it with the eight (6-18) screws and
flat washers. Torque the screws to 5.5 ± 1 in-lb.

Install the printer paper and cover.

Restore power.

7.3 PRINT HEAD ASSEMBLY
The following procedure describes the removal and installation of the print head assembly. When
installing the print head, carriage alignment is checked and the print head is aligned. Failure to perform these procedures will shorten the head life and cause poor print quality.
Print Head Removal

7.3.1
I.

Perform the printer housing removal procedure (Paragraph 7.2.1).

Remove the ribbon spools and ribbon.

Open the rear access door on the cabinet.

Disconnect the ribbon cable connector from J6 on the power board (Figure 7-3).

Pull the ribbon cable from under the power board and up through the slot at the rear of the
cabinet.

Remove the four (4-40) screws and
kep nuts that secure the two ribbon
cable clamps to the cabinet base (Figure 7-5).

4-(8-32)

SCREWS

TIMING BELT AGAINST
CARRIAGE ASSEMBLY
LIP

Remove the four (6-32) screws, lockwashers, and flat washers that secure
the print head to the carriage and
remove the print head and the ribbon
cable (Figure 7-4).

Figure 7-4 Print Head Removal

7-5

7.3.2

Print Head Installation
1. Dress the print head ribbon cable as shown in Figure 7-5 and secure the two ribbon cable
clamps and terminal strip to the cabinet base with the four (4-40) screws and lockwashers.

TERMENAL
STRIP

I ~~-t:
' - BOTTOM OF
"'-HEAD
ASSEMBLY
CP-2255

Figure 7-5

Print Head Cable

2. Dress the ribbon cable under the dc motor, down through the slot in the rear ofthe cabinet,
under the power board, and reconnect the ribbon cable connector to J6 on the power board
(Figure 7-3).
CAUTION
Move the carriage to the extreme left to ensure that
there is adequate slack in the print head cable to prevent any strain being placed on the cable or print
head board. If you can place your finger in the cable
loop (under the print head), there is adequate slack.
3. Close the rear access door on the cabinet.
4. Secure the new print head with the four (6-32) screws, lockwashers, and flat washers, ensuring that the timing belt is against the plastic lip (Figure 7-4). Make the screws finger tight.
CAUTION

It is possible to set the Carriage Adjustment lever
beyond the minimum gap position. If this is down, the
correct head gap adjustment cannot be made.
5. Set the Carriage Adjustment lever to the minimum gap position (detent closest to the print
bar).
CAUTION
Ensure that the feeler gauge rides between the protrusions on the print head. Do not exert excessive
force on the print head when making the adjustment;
it will cause the carriage shaft to bow, resulting in
more than 0.3048 mm (0.012 inch) of clearance.
7-6

PRINT HEAD

0.012
FEELER GAUGE

6-32 SCREWS TO
BE TIGHTENED 10 ± 2
INJLBS. OF TORQUE

CAUTION
ENSURE THAT FEELER GAUGE IS INSERTED
BETWEEN THE PROTRUSIONS ON THE
PRINTHEAD. FAILURE TO DO SO WILL RESULT
IN IMPROPER CLEARANCE AND SHORTEN
THE LIFE OF THE PRINTHEAD.
7393-06

Figure 7-6 Print Head Adjustment

7-7

CAUTION
Ensure that the feeler gauge rides between the protrusions on the print head. Do not exert excessive
force on the print head when making the adjustment;
it will cause the carriage shaft to bow, resulting in
more than 0.3048 mm (0.012 inch) of clearance.
6. Adjust the print head gap with the carriage in the center of travel. Place the 0.3048 mm
(0.012 inch) flat feeler gauge between the print head jewel and the front surface of the print
bar. Push the print head snug against the feeler (Figure 7-6).
CAUTION
Do not apply more than the recommended torque
when tightening the print head screws or the molded
inserts in the carriage assembly may be damaged.
7. Tighten the four (6-32) screws to 10 ±2 in-Ib of torque.
8. Move the print head to the extreme right or left and check for 0.3048 ± 0.0508 mm (0.012 ±
0.002 inch) clearance.
9. Replace the ribbon and ribbon spools (Chapter 3).
10. Slide the carriage assembly along the carriage shaft to ensure that nothing is binding. Check
to ensure that the ribbon is not rubbing against the line indicator.
11. Perform the printer housing installation (Paragraph 7.2.2).

7-8

7.4 TIMING BELT
The following procedure describes the removal and installation of the timing belt.
7.4.1 Timing Belt Removal
1.

Perform the printer housing removal procedure (Paragraph 7.2).

Perform the print head removal procedure (Paragraph 7.3).

Push the carriage assembly to the extreme left. Slip the timing belt off the dc motor pulley
while turning the pulley clockwise. Remove and discard the timing belt.

7.4.2 Timing Belt Installation
1.

With the belt tension spring (Figure 77) in place, press the left-hand pulley
against the printer mechanism and
slip on the new timing belt.
NOTE
Earlier versions of the LA36 do not
contain timing belt screws.

Rotate the timing belt screw until it
just touches the ribbon drive assembly. Screws should not exert pressure
on the ribbon drive assembly.

Perform the print head installation
procedure (Paragraph 7.3).
7937-4

Perform the printer housing installation procedure (Paragraph 7.2).

Figure 7-7 Belt Tension Spring Location

7-9

7.5 CARRIAGE ASSEMBLY AND CARRIAGE SHAFTS
The following procedure describes the removal and installation of the carriage assembly and/or the
carriage shafts. The carriage shafts must be removed first in order to replace the carriage assembly.
7.5.1

Carriage Assembly and Carriage Shafts Removal
1. Perform the printer housing removal procedure (Paragraph 7.2.1).
2. Remove the ribbon spools and ribbon.
3. Remove the four (6-32) screws, lockwashers, and flat washers that secure the print head to
the carriage (Figure 7-4). Set the print head carefully on the cabinet base.
4. Push the carriage assembly to the extreme left. Slip the timing belt off the dc motor pulley
while turning the pulley clockwise. Remove the belt.
5. If installed, remove the three (8-32) screws, washers, and lockwasher from the top of form
assembly (Figure 7-18) and set the assembly aside.
6. Remove the three (8-32) screws, washers, and standoffs from the ftont and
rear of the dc motor (Figure 7-8).

CARRIAGE SHAFT MOUNTING
(10-32 ALLEN-CAP SCREWS I

OCMOTOR
REAR MOUNT

7. Remove the pushrod retaining ring
(Figure 7-14) from the ribbon drive
assembly.
8. Remove the one (8-32) screw, lockwasher, and flat washer (Figure 7-14)
that secure the ribbon drive assembly
to the upper pivot tab.
9. Remove the ribbon drive assembly by
pulling out at the top. This will free
the assembly from the upper pivot
tab. Lift up the ribbon drive assembly
to clear the tab and remove.

PRINTER MECHANISM
FRONT MOUNT

DC MOTOR
FRONT MOUNTING HOLES
8433-10

NOTE
The nut on top of ribbon drive assembly
is loose and can be easily lost.

Figure 7-8

7-10

Carriage Shaft Screw Access

REMOVE 4 (10-32l ALLEN CAP
SCREWS FROM CARRIAGE SHAFTS

lO. Mark both ends of each carriage shaft
so that they may be reinstalled in their
original position, if applicable.
11. Remove the two (lO-32) screws, lockwashers, and flat washers connecting
the front of the printer mechanism
(Figure 7-S) to the cabint base.
12. Loosen the 7/16 hex-head (1/4-20)
screw securing the print bar to the
right-hand side plate approximately
5.S mm (l/S inch) (Figure 7-9).
NOTES

SIDE PLATE
STiFFNER

1. Record the location of any carriage
shaft shims obsened when remo,ing
the carriage shafts.

Figure 7-9

2. The oiler springs are connected to
the end plates and are not part of the
carriage assembly.

PRINT BAR
114-20 HEX-HEAD
SCREW (LOOSEN 1/8 IN.l

Carriage Shaft Removal

13. Remove the four (lO-32) Allen-cap
screws, split lockwashers, and flat
washers from the ends of the two carriage shafts (Figure 7-9).
14. While holding the carriage shafts,
gently tap the inside of the right-hand
side plate with a wood or plasic mallet
directly above the print bar (Figure 7lO). Lift up and pull out the carriage
shaft or shafts from the oiler springs
and the side plate.
15. Remove the defective carriage assembly or carriage shaft.
OILERS

CARRIAGE SHAFTS
(LIFT UP AND SLIDE
OUT OF OILERSl
8433-28

Figure 7-lO

7-11

Printer Mechanism End Plate
Loosening

7.S.2

Carriage Assembly and Carriage Shaft Installation

1. Slide both carriage shafts through the carriage assembly.
2. Slide the carriage shafts through the oilers (Figure 7-1O) to the left end plate.
3. Set the other end of the carriage shafts into the right-hand end plate.

NOTE
Carriage shafts, when being installed, are to be
replaced in their original positions, as mArked in the
removal procedure.

4. Install four (10-32) Allen-cap screws, flat washers, and lockwashers through the end plates
and secure the carriage shafts.
5. Install the carriage shaft shims (if any) in the location observed during the removal
procedure.
6. Hand tighten the screws, ensuring that the carriage shafts are seated in the end plates.
7. Torque the two carriage shafts to 18 ± 2 in-lb.
8. Set the alignment gauge on the extreme left side of the carriage shafts and zero the gauge by
rotating the gauge bezel (Figure 7-5).
9. Move the alignment gauge to the extreme right of the carriage shafts.
10. Adjust the right side of the print bar to obtain an indication of 0 ± 0.0005 on the gauge.
11. Torque the 7/16 hex head (1/4-20) screw on the right side of the print bar to 75 ± 2 in-lb.
12. Loosen the two (1O-32) Allen-head screws on the front carriage shaft (shaft closest to the
front panel switches).
13. Slide the alignment gauge along the total length of the carriage shafts. It may be necessary to
rotate the front carriage shaft (Figure 7-11), and/or add shims to obtain the following
values:
• The maximum deviation along the entire length of the carriage shafts is 0.004 (total
indicator reading), with the two ends of the carriage shafts readings equal within 0.0015
inch.
14. Torque the front carriage shaft to 18 ± 2 in-Ib and check the tolerances listed in step 13.
Loosen the front carriage shaft and repeat step 13 if necessary.
15. Secure the dc motor with three (8-32) screws, washers, and standoffs. Torque to 18 ± 2 in-lb.
16. If applicable, secure top of form bracket assembly with three (8-32) screws, washers, and
lockwashers. Torque to 18 ± 2 in-lb.
7-12

PRINTBAR
0

B
0

RIGHT HAND
SIDE PLATE

LEFT HAND
SIDE PLATE

10-32
ALLEN CAP
SCREW

g
0

ALIGNMENT
TOOL

Figure 7-11

ROTATE SHAFT TO OBTAIN
A MAXIMUM DEVIATION ALONG
NTiRE LENGTH OF THE
CARRIAGE SHAFTS OF 0.004
(TOTAL INDICATOR READINGl

CP-3007

Carriage Shaft Parallelism / Alignment

17. Secure the front of the printer mechanism with two (10-32) screws, flat washers, and lockwashers. Torque to 5 ± in-lb.
NOTE
When installing the ribbon assembly, ensure that the
PAPER OUT switch wires are under the pushrod.

18. Rotate the ribbon drive pulley until the clutch eccentric is at its highest point (Figure 7-14).
19. Move the ribbon assembly push rod through the left-hand side plate. Move the rear of the
ribbon drive assembly toward the side plate and engage the lower pivot point.
20. Slide the upper pivot point under the pivot tab on the side plate and secure with one (8-32)
screw, lock washer, and flat washer; hand tighten.
21. Replace the retaining ring that holds the pushrod in the ribbon chassis.
22. Insert the belt tension spring between the left-hand side plate and the ribbon drive assembly.
23. Slip the timing belt on the ribbon drive pulley and the dc motor pulley.
24. Rotate the ribbon drive pulley and check the travel of the pushrod to either side of center of
the elongated slot in the ribbon chassis. The travel should be equal on either side of center
(Figure 7-15).
7-13

25. To attain equal travel, move the ribbon drive upper pivot point in the direction of the
shortest distance of travel. When travel is equal on both sides of the elongated hole, tighten
the 8-32 upper pivot screw to 18 ± 2 in-lb of torque.
NOTE
The eccentric tab should be bent at a 90 degree angle
(Figure 7-15) when viewed from the left side of the
unit. If the angle is not at 90 degrees, bend to the
correct angle. This is done to prevent the tab from
touching the spring [0.254 to 0.508 mm (0.010 to
0.020 inch) clearance].
26. Perform the print head installation procedure (Paragraph 7.3.2).
27. Check the printer mechanism alignment (Chapter 8).
28. Perform the printer housing installation procedure (Paragraph 7.2.2).

7.6 CARRIAGE BUSHING AND CARRIAGE LEVER
The following procedure describes the removal and installation of the carriage bushing and carriage
lever. To perform this procedure, the carriage assembly must be removed from the carriage shafts.

7.6.1

Carriage Bushing and Carriage Lever Removal
1.

Perform the carriage assembly and carriage shafts removal procedure (Paragraph 7.5.1).

Place the carriage assembly on a workbench.

Remove the plain bushing (Figure 7-12).

To remove the eccentric bushing or carriage lever, set the lever to the position shown in
Figure 7-13 and pry off one side of the carriage lever.
NOTE
Do not bend the carriage lever further than
necessary.

Pull off the carriage lever and remove the eccentric bearings.

7-14

7937-18

PLAIN BUSHING

Figure 7-12 Plain Bushing and Spring Replacement

Carriage Bushing and Carriage Lever Installation

7.6.2

Install the new eccentric bushing in
the carriage assembly.

Align the slots in the bushing with the
carriage lever and snap the carriage
lever into the carriage assembly (Figure 7-13). Set the carriage lever to the
no. 1 position.

Insert the plain bushing into the carriage assembly (Figure 7-12).

Perform the carriage assembly and
carriage shafts installation procedure
(Paragraph 7.5.2).
CARRIAGE LEVER
(MOVE LEVER TO
THIS POSITION AND
PRY OFF)
7937-22

Figure 7-13 Carriage Lever
and Eccentric Bearing Replacement

7-15

7.7 RIBBON DRIVE ASSEMBLY
The following procedure describes the removal and installation of the ribbon drive assembly.
7.7.1

Ribbon Drive Assembly Removal
1.

Perform the printer housing removal procedure (Paragraph 7.2.1).

Remove the ribbon spools and ribbon.

Slip the timing belt off the dc motor pUlley.

Remove the retaining ring that holds the pushrod in the ribbon chassis (Figure 7-14).

Rotate the ribbon drive pulley until the clutch eccentric is at its highest point (Figure 7-14).

Remove the 8-32 screw, lock washer, and flat washer that secure the ribbon drive to the
upper pivot tab on the left-hand side plate (Figure 7-14).

Remove the ribbon drive by pulling out at the top. This will free the assembly from the
upper pivot tab. Lift up on the ribbon drive to clear the lower pivot.
NOTE
The nut on ribbon drive assembly is loose and can be
easily lost.

Carefully remove the ribbon drive and the pushrod.

PUSH ROD
RETAINING RING

RAISED PORTION
OF PIVOT TAB

RIBBON CHASSIS

COMPRESSION
SPRING

TAB
7393-10

Figure 7-14

Ribbon Drive Assembly Removal
7-16

7.7.2

Ribbon Drive Assembly Installation
1. Rotate the ribbon drive pulley on the new ribbon drive until the clutch eccentric is at its
highest point (Figure 7-14).
NOTE
Ensure that the PAPER OUT switch wires are under
the pushrod when installing the ribbon drive
assembly.
2. Push the pushrod through the left-hand side plate.
3. Push the rear of the drive assembly toward the side plate and engage the lower pivot point.
4. Slide the upper pivot point under the pivot tab on the side plate and secure it with the 8-32
screw, lockwasher, and flat washer. Make the screw finger tight.
5.

Replace the retaining ring that holds the pushrod in the ribbon chassis.

6. Insert the compression spring between the left-hand side plate and the ribbon drive.
7.

Replace the timing belt on the ribbon drive pulley and the dc motor pulley.

Rotate the ribbon drive pulley and check the travel of the pushrod to either side of center of
the elongated slot in the ribbon chassis. The travel should be equal on either side of center
(Figure 7-15).

9. To attain equal travel, move the ribbon drive upper pivot point in the direction of the
shortest distance of travel. When travel is equal on both sides of the elongated hole, tighten
the 8-32 upper pivot screw to 18 ± 2 in-lb of torque.
NOTE
The eccentric tab should be bent at a 90 degree angle
(Figure 7-14) when viewed from the left side of the
unit. If the angle is not at 90 degrees, bend it to the
correct angle. This is done to prevent the tab from
touching the spring [0.254 to 0.508 mm (0.010 to
0.020 inch) clearance].
10. Replace the ribbon and ribbon spools.
11. Perform the printer housing installation procedure (Paragraph 7.2.2).

7-17

7.8 RIBBON DRIVE FAFNIR BEARING
The following procedure describes the removal and installation of the ribbon drive Fafnir bearing. To
perform this procedure, the ribbon drive assembly must be removed.

Ribbon Drive Fafnir Removal

7.8.1
1.

Perform the ribbon drive assembly removal procedure (Paragraph 7.7.1).

Loosen the 6-32 Allen-head screw that secures the collar clamp and drive pulley to the
ribbon drive shaft. Remove the collar clamp and drive pulley (Figure 7-17).

CENTERLINE OF
ELONGATED HOLE

PIVOT TAB

RIBBON DRIVE
PUSHROD

.'880' 0.'" '""" ~:

V·"

~ ~I'=i=-_=____~ '-=i-:.rEo.-:.:_ _ _ _ _ _ _!@_)II___L7 • o
IIb

ODD

II ,..-111 011 wE_lIlT Illy
'";m~lIr • II 5

IT "'"

u 1111 . 0 iii p II I III ~ III "III-uji

II!",' H J .; II[ ': III : II[ :' 11/: """II
z xIII c III v III Bill N III Mill ~ > III \ II "",llu.ql
0

o
o

o
NOTE:
Travel of pushrod to be equal on both
sides of the elongated hole.

CP-1~65

Figure 7-15

Ribbon Drive Adjustment

7-18

Remove the two {8-32) screws, nuts,
and lockwashers that secure the Fafnir bearing to the ribbon drive bracket
(Figure 7-16).

Loosen the 4-40 set screw that secures
the Fafnir bearing on the ribbon drive
shaft (Figure 7-16).

Push the ribbon drive shaft toward the
rear of the ribbon drive until the shaft
clears the ribbon drive bracket.
(Always turn the shaft in the counterclockwise direction when pushing
through the one-way clutch.)

Remove the Fafnir bearing from the
ribbon drive shaft and set the bearing
aside.

ECCENTRIC

RIBBON DRIVE

SPRING

SET SCREW

SCREW
7393-3

Figure 7-16

Fafnir Bearing Removal

RIBBON
DRIVE
SHAFT

o
o
COLLAR
CLAMP

RIBBON
DRIVE
PULLEY

Figure 7-17

Cp·3010

Ribbon Drive Shaft Adjustment

7-19

7.8.2

Ribbon Drive Fafnir Installation
1.

Place the new Fafnir bearing on the ribbon drive shaft and push the shaft toward the pulley
end of the ribbon drive until the Fafnir bearing can be seated in the ribbon drive bracket.
(Always turn the shaft in a counterclockwise direction when pushing through the one-way
clutch.)

Secure the Fafnir bearing to the ribbon drive bracket with the two (8-32) screws, nuts, and
lockwashers. The nuts go on the outside of the ribbon drive bracket.

Slide the ribbon drive shaft toward the front of the ribbon drive until it extends 43.434 ±
0.508 mm (1.71 ± 0.02 inch) beyond the ribbon drive bracket (Figure 7-17). Tighten the 4-40
screw-in Fafnir bearing to 8 ± 1 in-lb of torque. Turn the shaft in a clockwise direction to
ensure freedom of movement.

Repla~e the ribbon drive pulley and collar clamp on the ribbon drive shaft and adjust them
to give a clearance of 7.366 ± 0.762 mm (0.29 ± 0.03 inch) between the ribbon drive bracket
and the ribbon drive pulley (Figure 7-17). Tighten the 6-32 Allen-head screw to 12 ± 2 in-lb
of torque.

Check that the coils of the backstop spring do not overlap.

Perform the ribbon drive assembly installation procedure (Paragraph 7.7.2).

7.9 RIBBON ECCENTRIC WITH CLUTCH/BACKSTOP SPRING
The following procedure describes the removal and installation of the ribbon eccentric with the
clutch/backstop spring. To perform this procedure, the ribbon drive assembly must be removed.
Ribbon Eccentric with Clutch/Backstop Spring Removal

7.9.1
1.

Perform the ribbon drive assembly removal procedure (Paragraph 7.7.1).

Loosen the 6-32 Allen-head screw that secures the collar clamp and drive pulley to the
ribbon drive shaft. Remove the collar clamp and drive pUlley.

Loosen the 4-40 set screw that secures the Fafnir bearing on the ribbon drive shaft (Figure 716).

Remove the retaining ring that holds the pushrod in the ribbon eccentric (Figure 7-17).

Slide the ribbon shaft toward the rear of the ribbon drive assembly until it clears the Fafnir
bearing, eccentric with the clutch and the rear bearing. (Always turn the shaft in a counterclockwise direction when pushing through the one-way clutch.)

Remove the backstop spring from the ribbon eccentric with the clutch (Figure 7-16).
Ribbon Eccentric with Clutch/Backstop Spring Installation

7.9.2
1.

Install the backstop spring on the new ribbon eccentric with the clutch or backstop spring.
Apply one drop of No. 30 SAE oil on the spring.

7-20

Slide the pushrod into the ribbon eccentric and replace the retaining ring.

With the clutch, eccentric, and backstop spring assembled, engage the backstop spring in the
clutch retaining tab.

Slide the ribbon drive shaft through the rear bearing, eccentric washer, eccentric with clutch·,
Fafnir bearing, and ribbon drive bracket. (Always turn the shaft in a counterclockwise direction when pushing through the one-way clutch.)

Slide the ribbon drive shaft toward the front of the ribbon drive until it extends 43.434 ±
0.50S mm (1.71 ± 0.02 inch) beyond the ribbon drive bracket (Figure 7-17). Tighten the 4-40
screw-in Fafnir bearing to S ± 1 in-Ib of torque. Turn the shaft in a clockwise direction to
ensure freedom of movement.

Replace the ribbon drive pulley and collar clamp on the ribbon drive shaft and adjust them
to give a clearance of 7.366 ± 0.762 mm (0.29 ± 0.03 inch) between the ribbon drive bracket
and the ribbon drive pulley (Figure 7-17). Tighten the 6-32 screw to 12 ± 2 in-Ib of torque.

Check that the coils of the backstop spring do not overlap.

Perform the ribbon drive assembly installation procedure (Paragraph 7.7.2).

7.10 RIBBON DRIVE PULLEY
The following procedure describes the removal and installation of the ribbon drive pulley.
7.10.1

Ribbon Drive Pulley Removal

Perform the printer housing removal procedure (Paragraph 7.2.1).

Slip the timing belt off the dc motor pulley.

Loosen the 6-32 screw that secures the collar clamp and drive pulley to the ribbon drive
shaft. Remove the collar clamp and the drive pulley (Figure 7-17).

7.10.2 Ribbon Drive Pulley Installation
1.

Remove the collar clamp from the defective pulley and hand press it onto the new drive
pulley (front edges of the collar clamp and drive pulley to be coincident) (Figure 7-17) .

Replace the ribbon drive pulley ~nd the collar clamp on the ribbon drive shaft and adjust
them to give a clearance of 7.366 ± 0.762 mm (0.29 ± 0.3 inch) between the ribbon drive
bracket and the ribbon drive pulley (Figure 7-17). Tighten the 6-32 screw to 12 ± 2 in-Ib of
torque.

Slip the timing belt onto the pulleys.

Perform the printer housing installation procedure (Paragraph 7.2.2).

7-21

7. Select channel I, set it vertical to Cl, and trigger the source to the channell.
8. Adjust the scope for one duty cycle full scale (Figure 7-20). Observe the duty cycle.

CAUTION

Exercise extreme caution when adjusting the encoder
to avoid bending or damaging tile disk or coming in
contact with the sharp rotating disk.

r--5O%DUTY
CYCLE

MAXIMUM JITTER
(1.4 DIVISIONS MAXIMUM)

SCOPE DIVISIONS

10
M-Q585

Figure 7-20 Encoder 50 Percent Duty Cycle Waveshape
9. If the channel 1 signal (Figure 7-20)
does not have a 50 percent duty cycle
(jitter included), adjust R I on the
encoder assembly (Figure 7-21).

PHASE AD.lUSTMENT SCREWS

to. Check the channel 1 jitter (Figure 720). The maximum allowable jitter is
1.4 divisions (or ±0.7 division).
11. Select channel 2, set vertial to C2, and
trigger the source to channel 2.

12. Adjust the scope for one duty cycle
full scale (Figure 7-20). Observe the
duty cycle.

7383·5

Figure 7-21
7-24

Encoder (Rear View)

Slide the pushrod into the ribbon eccentric and replace the retaining ring.

With the clutch, eccentric, and backstop spring assembled, engage the backstop spring in the
clutch retaining tab.

Slide the ribbon drive shaft through the rear bearing, eccentric washer, eccentric with clutch,
Fafnir bearing, and ribbon drive bracket. (Always turn the shaft in a counterclockwise direction when pushing through the one-way clutch.)

Slide the ribbon drive shaft toward the front of the ribbon drive until it extends 43.434 ±
0.508 mm (1.71 ± 0.02 inch) beyond the ribbon drive bracket (Figure 7-17). Tighten the 4-40
screw-in Fafnir bearing to 8 ± 1 in-Ib of torque. Turn the shaft in a clockwise direction to
ensure freedom of movement.

Check that the coils of the backstop spring do not overlap.

Perform the ribbon drive assemli>ly installation procedure (Paragraph 7.7.2).

7.10 RIBBON DRIVE PULLEY
The following procedure describes the removal and installation of the ribbon drive pulley.
7.10.1

Ribbon Drive Pulley Removal

Perform the printer housing removal procedure (Paragraph 7.2.1).

Slip the timing belt off the dc motor pulley.

Loosen the 6-32 screw that secures the collar clamp and drive pulley to the ribbon drive
shaft. Remove the collar clamp and the drive pulley (Figure 7-17).

7.10.2 Ribbon Drive Pulley Installation
1.

Remove the collar clamp from the defective pulley and hand press it onto the new drive
pulley (front edges of the collar ~amp and drive pulley to be coincident) (Figure 7-17).

Replace the ribbon drive pulley and the collar clamp on the ribbon drive shaft and adjust
them to give a clearance of 7.366 ± 0.762 mm (0.29 ± 0.3 inch) between the ribbon drive
bracket and the ribbon drive pulley (Figure 7-17). Tighten the 6-32 screw to 12 ± 2 in-Ib of
torque.

Slip the timing belt onto the pulleys.

Perform the printer housing installation procedure (Paragraph 7.2.2).

7-21

7.11 DC MOTOR AND ENCODER ASSEMBLY
The following procedure describes the removal and installation of the dc motor and encoder assembly.
After completion of the dc motor and encoder installation, the encoder must be adjusted.
NOTE
If applicable, the top of form assembly must be
removed to gain access to the dc motor rear mounting screw.
7.11.1

DC Motor and Encoder Assembly Removal

Perform the printer housing removal procedure (Paragraph 7.2.1).

Remove the ribbon spools and ribbon.

Remove the 4-40 screw and nut from the terminal strip (Figure 7-18).

Slip the timing belt off the dc motor pulley.

Remove the dc motor cables from the cable clamps and fuse holder, and disconnect J4 from
the power board. Cut any cable ties associated with the dc motor cable.

Remove the three (8-32) screws and hex standoffs that secure the dc motor to the right-hand
side plate and remove motor (Figure 7-19).

If applicable, disconnect the ground wire from the dc motor.

Figure 7-18

DC Motor/Encoder Cabling
MOUNTING

Figure 7-19

7-22

DC Motor/Encoder Removal

7.11.2 DC Motor and Encoder Assembly Installation
1.

If applicable, connect the ground wire to the new dc motor.

Secure the new dc motor to the right-hand side plate with the three (8-32) screws and hex
standoffs. Tighten the screws to 18 ± 2 in-lb.

Secure the capacitor terminal strip with a 4-40 screw and nut. Torque the 4-40 screw to 8 ± 1
in-lb.

Thread the dc motor and encoder cables down through the slot at the rear of the cabinet.

Secure the cables in the cable clamp and the fuse holder. Reconnect the connector to J4 on
the power board.

7.11.3 Encoder Electrical Adjustment
The dc motor and encoder assembly must be checked after installation for the correct waveform timing
relationships. If necessary, the encoder can be adjusted to achieve the correct timing relationships.
NOTE
If applicable, tape I down cover interlock to perform
adjustment.
1. Set up the scope as follows:
•
•

Volts/Division: 1 V
Time Division: approximately 20 ILS

2. Disconnect the wire from the power board to the servo fuse holder. Using a test lead, connect +5 V from the logic board to the servo fuse holder.
3. Connect scope CHI probe to M7722 E6-6, M7723 E2-6, or M7728 E18-6
4. Connect scope CH2 probe to M7722 E6-8, M7723 E2-8, or M7728 EI8-8.
NOTE
The timing belt must be off the dc motor pulley when
performing this procedure.
5. Carefully remove the encoder's protective cover. Do not apply any pressure to the disk when
removing the cover.
6. Restore power to the LA36 (set the POWER switch to ON). The motor will rotate clockwise
as viewed.
NOTE
If the encoder is drastically out of adjustment, the
motor may tum in either direction and the speed may
vary from very fast to zero. Encoder readjustment
will correct these conditions.
If the. motor is turning counterclockwise, the waveform for quadrature will be reversed. That is, CHI
will lead by 90 degrees.

7-23

7. Select channell, set it vertical to Cl, and trigger the source to the channell.
8. Adjust the scope for one duty cycle full scale (Figure 7-20). Observe the duty cycle.
CAUTION
Exercise extreme caution when adjusting the encoder
to avoid bending or damaging the disk or coming in
contact with the sharp rotating disk.

Ir---

SCOPE DIVISIONS

50% DUTY
CYCLE

MAXIMUM JITTER

10
M-G585

Figure 7-20 Encoder 50 Percent Duty Cycle Waveshape
9. If the channel 1 signal (Figure 7-20)
does not have a 50 percent duty cycle
(jitter included), adjust Rl on the
encoder assembly (Figure 7-21).

PHASE ADJUSTMENT SCREWS

10. Check the channell jitter (Figure 720). The maximum allowable jitter is
1.4 divisions (or ±0.7 division).
11. Select channel 2, set vertial to C2, and
trigger the source to channel 2.
12. Adjust the scope for one duty cycle
full scale (Figure 7-20). Observe the
duty cycle.

Figure 7-21
7-24

Encoder (Rear View)

13. If the channel 2 signal (Figure 7-20) does not have a 50 percent duty cycle Gitter included),
adjust R2 on the encoder assembly (Figure 7-21).
14. Check the channel 2 jitter (Figure 7-20). Maximum allowable jitter is 1.4 divisions (or ±0.7
divisions).
15. Set up the scope per Figure 7-22.
16. Channel 2 should lead channell by 90 degrees ± 20 degrees (Figure 7-22). If not, loosen the
two encoder screws, reposition the encoder subassembly as required, and tighten the screws.
Glyptol R 1 and R2.
CAUTION
Exercise extreme caution when adjusting the encoder
to aloid bending or damaging the disk or coming in
contact with the sharp rotating disk.
17. Turn the power off and carefully install the encoder cover.
18. Turn the power on and recheck the encoder waveshapes to ensure that the encoder disk has
not been damaged when installing the cover.
19. Turn the power off.
20. Remove the test lead between +5 V and the servo fuse holder. Reconnect the lead from the
power board to the servo fuse holder.
21. Remove the scope leads and close the rear access door.
22. Reinstall the timing belt on the dc motor pulley.
23. Perform the printer housing installation procedure (Paragraph 7.2.2).
SCOPE SETUP
90° LEAD-I

4VI
4VI

VOLTS/DIV:

VERTICAL MODE:

ALT

TIME/DIV:

60 /-Is

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1. AC.INT. POS

CH1 to:

M7722 E6-6
M7723 E2-6
M772SE1S-6

CH2to:

M7722 E6-S
M7723 E2-S
M772S E1S-S

GND

M-0724

Figure 7-22

Encoder Phasing Adjustment
7-25

7.11 PRINTER MECHANISM ASSEMBLY
The following procedure describes the removal and installation of the printer mechanism assembly.
7.11.1

Printer Mechanism Assembly Removal
1. Perform the printer housing removal procedure (Paragraph 7.2.1).
2. Remove the ribbon spools and ribbon.
3. Remove the four (6-32) screws, lockwashers, and flat washers that secure the print head to
the carriage and set the print head (Figure 7-4) aside.
4. Open the rear access door.
5. Remove the stepping motor wires
from the cable clamp and clip the necessary cable ties. Disconnect the connector from J5 on the power board.
Pull the disconnected wires up
through the cabinet base.
6. If applicable, remove the top of form
assembly.
7. Remove the 6-32 screw, fastening
ground wire to the cabinet base (Figure 7-23).
8. Remove the speaker wires.
8433-14

9. Remove the 4-40 screw and nut from
the terminal strip (Figure 7-18).

Figure 7-23 Printer Mechanism
Removal Preparation

10. Remove the dc motor cables from the
cable clamps and fuse holder, and disconnect J4 from the power board.
NOTE
When removing the printer mechanism,
check for rubber spacers between the
base and printer mechanism.
II. Remove the four (10-32) screws, lockwashers, and flat washers that secure
the printer mechanism to the cabinet
base (Figure 7-24). Carefully remove
the printer mechanism from the cabinet base.

Figure 7-24
7-26

Printer Mechanism Removal

7.12.2

Printer Mechanism Installation
1. Remove the ground wire from the old printer mechanism and connect it to the new printer
mechanism.
2. Slide the carriage assembly to the left side of the printer mechanism.
3. Tilt and carefully place the new printer mechanism on the cabinet base. For printers using
rubber spacers, install the spacers between the printer mechanism and cabinet base.
4. Secure the printer mechanism with four (10-32) screws,lockwashers, and flat washers. Make
the screws finger tight.
5. If applicable, secure the top of form assembly to new printer mechanism.
6. Thread the cables and wires down through the slots at the rear of the cabinet.
7. Secure the stepping motor wires in the cable clamp. Reconnect the connector to J5 on the
power board.
8. Secure the dc motor wires in the cable clamps. Reconnect the wires to the fuse holder, and
the connector to J4 on the power board.
9. Connect the ground wires from the printer mechanism with a 6-32 screw.

10. Connect the wires to the speaker.
11. Secure the terminal strip with a 4-40 screw and nut.
12. Dress the cables and wires inside the cabinet and install cable ties as deemed necessary.
13. Close the rear access door on the cabinet.
14. Adjust the position of the printer mechanism (front to back) so that the front surface of the
print bar coincides with the centerline of the reference holes in the cabinet (Figure 7-25).
Tighten the four (10-32) screws to 5 ± 1 in-lb of torque.

7-27

10-32 SCREW

PRINTBAR

PRINTER
MECHANISM

10-32 SCREW

®
o

o
REFERENCE

~1'--""'-:'r''I;I

HOLE

COINCIDENT
WITH
C/l OF
FACE OF
PRINTBAR
~!IJ~~~~~~~~~~~~~~~~j1!~~I+-~+4- FRONT
REFERENCE HOLE

o
_ _ _.."...,.,0

10-32 SCREW

Figure 7-25

Printer Mechanism Alignment

15. Check that the carriage has 0.508 to
1.016 mm (0.020 to 0.040 inch) clearance from the bent-up flange on the
cabinet base when the Carriage
Adjustment lever is in the minimum
gap position (detent closest to the
print bar) (Figure 7-5). If necessary,
loosen the four (10-32) screws that
secure the printer mechanism to the
cabinet base and readjust the printer
mechanism to attain a 0.508 to 1.016
mm (0.020 to 0.040 inch) clearance
(Figure 7-26).

0.030 (0.020 TO 0.040) IN. CLEARANCE
BETWEEN FACE OF CARRIAGE
ASSEMBLY AND BENT-UP FLANGE

0.030
FEELER GAUGE

BENT-UP
FLANGE

CARRIAGE
ASSEMBLY

16. Replace the paper in the machine but
do not feed it up into the tractors. Pull
the paper up through the cabinet and
the printer mechanism to ensure that
there is no drag on the paper. If the
drag is encountered, perform paper
guide and printer mechanism adjustment (Paragraph 8.6). Remove the
paper from the machine.

7393-13

Figure 7-26

17. Perform the print head installation
procedure (Paragraph 7.3.2).
7-28

Printer Mechanism Adjustment

7.13 TRACTOR DRIVE SHAFTS AND TRACTOR ASSEMBLIES
The following procedure describes the removal and installation of the tractor drive shafts and tractor
assemblies. The tractor assemblies slip off the drive shafts once the tractor drive shaft removal is
completed.
7.13.1 Tractor Drive Shaft and Tractor
Assembly Removal
1.

Perform the printer housing removal
procedure (Paragraph 7.2.1).

Loosen the Tractor Adjustment knobs
on both tractors.

Remove the two retaining rings (Figure 7-27) on the left-hand side of the
tractor support shaft and drive shaft.

Slide both shafts to the left about
10.16 cm (4 inches) to remove the tractor assemblies. Pull the shafts (to the
left) out of the left-hand end plate to
remove the shafts.
RETAINING RINGS

Figure 7-27

7937·37

Tractor Removal

7.13.2 Tractor Drive Shaft and Tractor Assembly Installation
1.

Replace the defective tractor or drive shaft.

Slide the two tractor shafts halfway through the left side plate.
NOTE
When installing the tractor assemblies, ensure that
the index marks on the outside of the upper tractor
bushings coincide with the same nat on the square
shaft (Figure 7-28). If the bushings are not scribed,
rotate the tractors until a tractor pin on both tractors
are centered on the same nat.

Slide the tractor assemblies on the tractor shafts.

Position the tractor shafts in the side plates and secure them with three retaining rings
(Figure 7-27).

Slide the left-hand tractor from side to side. If it appears to bind or have excessive drag on
the shafts, grasp the bottom tractor shaft and move it up or down in its slots until the tractor
slides easily on the shafts.
7-29

Slide the left-hand tractor to the left so that the feed pins are 53.975 mm (2-1/8 inches) from
the left-hand side plate (Figure 7-28).

The right-hand tractor will be adjusted to the width of the paper or forms to be used.

Perform the printer housing installation procedure (Paragraph 7.2.2).

ALTERNATE
TRACTOR

INDEX
MARK 'i~~~~~

TRACTOR
BUSHING

TRACTOR
FEED PIN

RIGHT HAND
TRACTOR

7393-14

TRACTOR PHASING
CP-2251

Figure 7-28 Tractor Phasing/Adjustment

7-30

7.14 RIBBON CHASSIS ASSEMBLY
The following procedure describes the removal and installation of the ribbon chassis assembly.
7.14.1

Ribbon Chassis Assembly Removal

Perform the printer housing removal
procedure (Paragraph 7.2.1).
8-32

Remove the ribbon spools and
ribbon.

Remove the retaining ring that holds
the pushrod in the ribbon chassis (Figure 7-29).

Remove the four (6-32) screws and
lockwashers that secure the ribbon
chassis to the right- and left-hand side
plates (Figure 7-29).

Remove the two (8-32) screws and
lockwashers that secure the ribbon
chassis to the print bar (Figure 7-29).
NOTE
A cover interlock switch is connected to
the ribbon chassis on late model
printers.

Remove the speaker leads.

Remove the ribbon chassis and set it
aside.

Figure 7-29

RETAINING

8-32

Ribbon Chassis Removal

7.14.2 Ribbon Chassis Assembly Installation
1.

Secure the ribbon chassis to the print bar with the two (8-32) screws and lockwashers.
Torque the screws to 18 ± 2 in-lb.

Replace the four (6-32) screws and lockwashers that secure the ribbon chassis to the rightand left-hand side plates. Torque the screws to 12 ± 2 in-lb.

Line up the hole in the ribbon chassis with the pushrod, and replace the retaining ring that
holds the pushrod in place.

Connect the speaker leads to the speaker and secure it to the ribbon chassis with two cable
ties.

Install the ribbon spools and ribbon.

With the ribbon fully wound on the left spool, the ribbon moving right to left across the face
of the print head, and the ribbon grommet starting to pull the reverse sensor to the right, a
pull test on the carriage from the left to right should indicate a pull of no more than 1.814 kg
(4 lb) (Figure 7-30).

Perform the printer housing installation procedure (Paragraph 7.2.2).
7-31

RIBBON
IDLER

RIBBON
SPOOL

PRINTHEAD

RIBBON
SPOOL

I--

..B ~ h.

Ilei

Ei>

be-; ~

rev-

J--,...

~~
[~
~ :~q j
I~

I-

I/,

~]b b

-(@i

.t~ ~LI.

-;;;

J ~~
i

....

om\) ~.THAN 1 (.

t:J~
.

L....::..

~JDLil= I..Jf

r\i

...

I~I go.....-,--

~- 'I

=r~

I--

t------.

FT E:

NO MORE

4.0
LBS PULL

~ § ..

.......

~
jI:~li!l!'1nill

.::

- --I-

RIBBON
IDLER

CP-3,45

Figure 7-30

Ribbon Threading/Drag Test

7.15 RIBBON SPOOL RATCHET WHEELS AND FRIqION DISKS
The following procedure describes the removal and installation of the ribbon spool ratchet wheel(s)
and friction disks. The ribbon chassis assembly must be removed first in order to remove the ribbon
spool ratchet wheel(s) and friction disks.
7.15.1

Ribbon Spool Ratchet Wheel(s) and Friction Disk Removal

Perform the ribbon chassis assembly removal procedure (Paragraph 7.14.1).

Remove the adjusting screw and nut or retaining ring that secures the ratchet wheel and the
spool driver in the ribbon chassis (Figure 7-31).
NOTES
1. Record the order in which the parts are removed.
2. See Illustrated Parts Breakdown for an exploded
view.

Remove washers, compression ring, and ratchet wheel.

Set the ratchet wheel aside.
7-32

Remove the four old friction disks and clean each mounting surface.

Remove the protective paper from the four new friction disks and apply one each to the
spool driver wheel, ratchet wheel, and to each side of the ribbon chassis. Be sure that the
friction disk is applied to the side of the ratchet wheel that faces the ribbon chassis. Ensure
that surfaces are free of oil and moisture.

COMPRESSION SPRING
AND WASHER
FRICTION
DISKS

ADJUSTING SCREW
AND NUT

CP-1707

Figure 7-31

Friction Disk/Ratchet Wheel Replacement

7.15.2 Ribbon Spool Ratchet Wheel(s) and Friction Disk Installation
1.

Replace the ratchet wheel, compression spring, and the washers. The ratchet wheel teeth
must point in the direction shown in Figure 7-31.

Replace the screw and nut or retaining ring that secures the ratchet wheel and the ribbon
spool in the ribbon chassis.

Perform the ribbon chassis assembly installation procedure (Paragraph 7.14.2).
7-33

7.16 PRINT BAR
The following procedure describes the removal and installation of the print bar. The alignment gauge
must be used when performing this procedure.
7.16.1

Print Bar Remo,al

1. Perform the printer housing removal procedure (Paragraph 7.2.1).
2. Remove the ribbon spools and ribbon.
3. Slip the belt off the dc motor pulley.
4.

Remove the four (6-32) screws, lockwashers, and flat washers that secure the print head to
the carriage and set the print head aside (Figure 7-4).

5. Move the carriage assembly all the way to the left.
NOTE
Obsene the location of any shims between the carriage bars and the left-hand end plate.

6. Remove the three (8-32) screws and
hex standoffs that secure the dc motor
to the right side plate and set the
motor on its side (Figure 7-21).

PRINT BAR
(SPREAD THE LEFT-HAND

7. Remove the two (8-32) screws, lockwashers, and flat washers connecting
the ribbon chassis to the print bar.
8. Remove the two (10-32) Allen-cap
screws, split lockwashers, and flat
washers, connecting the right side of
the carriage shafts to the right-hand
side plate (Figure 7-32).
9. Remove the 10-32 screw connecting
the right front of the printer mechanism to the cabinet base (Figure 7-34).
10. Remove the two 7/16 hex-head (1/420) screws, lockwashers, and flat
washers from the print bar (Figure 732).

PRINT BAR MOUINT". . .
HOLE (1/-20 HEX-HEAD
SCREW)

11. Gently spread the right-hand side
plate and remove the print bar.

Figure 7-32

7-34

Print Bar Removal

Print Bar Installatien

7.16.2

1. Carefully slide the new print bar
into position and insert the carri~ge
shafts, print bar, and tractor shafts
into the right side plate. Once in
position, push the print bar as far
back as possible (toward the ribbon
chassis).
2.

CALIBRATE
BLOCK

Reinstall the carriage shaft shims, if
applicable, and secure the carria.ge
shafts with two (lO-32) Allen-cap
screws, lockwashers, and flat washers. Torque the screws to 18 ± 2 inlb.

GAUGE
ZEROEO

GAUGE

Figure 7-33 Calibrate Alignment
Gauge and Block

3. Calibrate the alignment gauge by setting the dial to zero with the calibrate block screwed
securely in place (Figure 7-33).
4.

Remove the calibrate block from the front of the gauge and set the gauge on the extreme
right of the carriage shafts (Figure 7-34).

Position the print bar for a zero indication on the gauge. Repeat this procedure with the
gauge on the extreme left of the carriage shafts.

6. Secure the ends of the print bar with two (1/4-20) hex-head screws, lock washers, and flat
washers. Hand tighten the screws.
7.

Repeat step 5 as many times as necessary, until the gauge indicates 0 ± 0.002 with the two
end readings being equal within 0.0015.

8. Slide the gauge across the full length of the carriage shafts. The total indicator reading must
not vary more than 0.004.
9. Torque the print bar with 7/16 hex-head nuts to 75 ± 5 in-lb.
lO.

Secure the ribbon chassis to the print bar with two (8-32) screws, lockwashers, and flat
washers. Torque the screws to 18 ± 2 in-lb.

11. Install the lO-32 screw connecting the right front printer mechanism to the cabinet base
(Figure 7-32).
12. Install the three (8-32) screws and hex standoffs that secure the dc motor to the right side
plate (Figure 7-19).
13. Perform timing belt installation (Paragraph 7.4.2), and the printer housing installation procedures (Paragraph 7.2.2).

7-35

RIGHT
SIDE OF
CARRIAGE
SHAFTS

BAR

+0.0015

-0.001

GAUGE MUST INDICATE 0.004 (TOTAL INDICATOR READING)
ACROSS PRINT BAR WITH THE TWO END READINGS BEING

ALIGNMENT
GAUGE

7937-31

Figure 7-34

Print Bar Alignment
7-36

7.17 IDLER GEAR ASSEMBLY
The following procedure describes the removal
and installation of the idler gear assembly.

IDLER GEAR
ASSEMBLY

8-32
SCREW

LINE FEED
KNOB

7.17.1 Idler Gear Assembly Removal
1.

Perform the printer housing removal
procedure (Paragraph 7.2.1).

Remove the two (8-32) screws, lockwashers, and flat washers that secure
the idler gear assembly to the lefthand side plate (Figure 7-35).

7.17.2 Idler Gear Assembly Installation
1.

0.002 IN.
BACKLASH AND EQUAL
DEPTH PENETRATION

Secure the new idler gear assembly to
the left-hand side plate with the two
(8-32) screws, lockwashers, and flat
washers. Make the screws finger tight.

7393·,n

Figure 7-35 Idler Gear Assembly
Removal

With the idler gear in mesh with the stepping motor gear and the tractor drive gear, adjust
the idler gear to achieve equal depth penetration and a backlash· of 0.0508 to 0.1778 mm
(0.002 to 0.007 inch) between each pair of gears (Figure 7-35). (The idler gear should be free
to slide in and out.) Rotate the gears to check the backlash in several places.

Tighten the two (8-32) screws to 18 ± 2 in-Ib of torque.

Rotate the Paper Advance knob to ensure that the gears turn freely.

Perform the printer housing installation procedure (Paragraph 7.2.2).

*Backlash is the amount a gear turns prior to turning the gear it meshes with.

7-37

7.18 STEPPING MOTOR ASSEMBLY
The following procedure describes the removal and installation of the stepping motor. The idler gear
assembly must be removed to remove the stepping motor assembly.
7.18.1 Stepping Motor Assembly Removal
I.

Perform the printer housing removal procedure (Paragraph 7.2.1).

Perform the idler gear assembly
removal procedure (Paragraph
7.17.1).

Open the rear access door.

Remove the stepping motor wires
from the cable clamp and clip the
necessary cable ties. Disconnect the
speaker leads. Disconnect the connector from J 5 on the power board
(Figure 7-3).

Pull the wires up through the slot at
the rear of the cabinet.

Remove the four (8-32) screws, flat
washers, lockwashers, and hex nuts
that secure the stepping motor to
the left-hand side plate. Set the
stepping motor aside (Figure 7-36).

Figure 7-36 Stepping Motor Removal

7.18.2 Stepping Motor Assembly Installation
1.

Secure the new stepping motor to the left-hand side plate with the four (8-32) screws, flat
washers, lockwashers, and hex nuts. The hex nuts and lock washers go on the inside of the
left-hand side plate. (Allow the stepping motor to drop to its lowest point in the elongated
slots.)

Tighten the four (8-32) screws to 18 ± 2 in-lb of torque.

Secure the stepping motor wires with cable ties and thread them under the printer mechanism and pushrod and down through the slot at the rear of the cabinet. Connect the speaker
leads to the speaker. Reconnect the connector to J5 on the power board.

Close the rear access door.

Perform the idler gear assembly installation procedure of the transformer assembly (Paragraph 7.17 .2).

7-38

7.19 TRANSFORMER ASSEMBLY
The following procedure destribes removal and installation procedure (Paragraph 7.17.2).
7.19.1

Transformer Assembly Removal
1. Remove the ac plug from the outlet box.
2. Perform printer housing removal procedure (Paragraph 7.2.1).
3. Open the rear access door on the cabinet.
WARNING
Power must be removed from the LA36 prior to performing this procedure.
4. Disconnect the connector from J3 on the power board (Figure 7-37).
NOTE
Steps 5 and 6 are only applicable to some printers.

ECTOR

TRANSFORMER IT1)

8-32

7393-16

Early LA36 Printer

Figure 7-37 Transformer Removal (Sheet 1 of 2)
7-39

TRANSFORMER
MOUNTING
SCREWS
(10F3)
8-32

TRANSFORMER

Current LA36 Printer

Figure 7-37 Transformer Removal (Sheet 2 of 2)

7-40

8433-7

5. Remove the two (8-32) screws and lockwashers that secure the fuse mounting bracket to the
cabinet (Figure 7-37).
6. Remove the green jumper wire from capacitor C5 (Figure 7-38).
7. Diconnect the quick-disconnect (Mate-N-Lok) from the fan assembly (Figure 7-37).

NOTE
Place a protective cloth or cardboard over the keys to
prevent scratching the keyboard.
8. Remove the four (8-32) screws, lockwashers, and flat washers that secure the keyboard bezel
to the cabinet base (Figure 7-9).

CAPACITOR C5

FUSE IF1)

WIRE

7393·7

Figure 7-38 Capacitor C5

7-41

9. Turn the keyboard upside down and remove the quick-disconnect (Figure 7-39) from the
POWER switch (SI).
10. If applicable, clip all the cable ties from the keyboard to the transformer.
11. Pull the wires that were removed from the power switch (SI) down through the slot in the
rear of the cabinet.
12. Remove the three or four (8-32) screws, lockwashers, and kep or captive nuts that secure the
transformer to the cabinet base. Disconnect the 115 V/230 V jumper (Mate-N-Lok) from
connector J1 and set the transformer aside (Figure 7-37).

REMOVE
THESE TWO
CONNECTORS

Early Version

Figure 7-39 Rocker Switch SI (Sheet 1 of 2)

7-42

b.
Figure 7-39

Current Version

Rocker Switch SI (Sheet 2 of 2)

7.19.2 Transformer Assembly Installation Procedure
1. Place the new transformer in the cabinet and secure with the three or four (8-32) screws,
lock washers, and kep or captive nuts. (Be sure to reconnect the ground strap to the screw on
the transformer.) Tighten the ground strap screw to 20 ± 2 in-Ib of torque.
2. Reconnect the Mate-N-Lok to the fan assembly.
3. Pull the wires up through the slot in the rear of the cabinet and reconnect the quickdisconnects to the power switch on the keyboard.
4. Replace the keyboard bezel and spacers if applicable, (spacers do not exist on all models) on
the cabinet base and secure with the four (8-32) screws, lockwashers, and flat washers.
5. Dress the wires and cables from the keyboard to the transformer and secure with cable ties.
6. Reconnect the connector to 13 on the power board.
7. Connect the 115 V/230 V jumper (Mate-N-Lok) to the transformer.

NOTE
Steps 8 and 9 are applicable only to some model
printers.
7-43

8. Replace the green jumper wire on capacitor C5.
9. Secure the fuse mounting bracket to the cabinet with the two (8-32) screws and lockwashers.

to. Close the rear access door on the cabinet.
11. Perform printer housing installation procedure (Paragraph 7.2.2).

7.20 LINE FILTER ASSEMBLY AND FUSE HOLDER
The following procedures describe the removal and installation of two types of line filters.
Type 1 line filter (Figure 7-38), located between the transformer and capacitors, is described in Paragraphs 7.20.1 and 7.20.2.
Type 2 line filter (Figure 7-40), located behind the transformer, is described in Paragraphs 7.20.3 and
7.20.4.

7.20.1

Type 1 Line Filter and Fuse Holder Removal
WARNING
Remove the LA36 ac plug from the outlet prior to
performing this procedure.

1. . Remove the LA36 ac plug from the ac outlet.
2.

Open the rear access door on the cabinet.

Remove the two (8-32) screws and lockwashers that secure the fuse mounting bracket to the
cabinet (Figure 7-37).
NOTE
Record the location of the wires to capacitor CS and
fuse FI prior to performing the next step.

Disconnect all external wires that connect to capacitor C5 and fuse Fl (Figure 7-38).

Remove the fuse mounting bracket and set aside.

7.20.2 Type 1 Line Filter and Fuse Holder Installation
1.

Install the new line filter or fuse holder in the fuse mounting.

Reconnect all external wires to capacitor C5 and fuse Fl in the new line filter.

Secure the fuse mounting bracket to the cabinet with the two (8-32) screws and lockwashers.

Close the rear access door on the cabinet.

Replace the printer paper and restore power to the LA36.

7-44

7.20.3 Type 2 Line Filter and Fuse Holder
Removal
1.

Perform the transformer removal procedure (Paragraph 7.19.1); however
do not disconnect the transformer
wires or cables.

Move the transformer slightly to the
left, enabling a clear view of the filter
assembly.

Remove the two (5/16) hex nuts and
lockwashers, and remove the filter
cover (Figure 7-40).

To replace the line filter, disconnect
the leads and remove two (5/16) hex
nuts, lockwashers, and spacers.

To remove the fuse holder, disconnect
the two wires and remove the fuse
holder nut.

AC LINE FUSE HOLDER

Figure 7-40 Type 2 Filter Assembly Removal
7.20.4 Type 2 Line Filter and Fuse Holder Installation
NOTE
When installing the line filter, the leads must be connected to the terminals recorded in the removal
procedure.
1.
2.
3.

Install the new fuse holder or line fuse.
Secure the line filter cover with two (5/16) hex nuts and lockwashers.
Perform the transformer assembly installation procedure (Paragraph 7.19.2).

7.21 LK02, LK03 KEYBOARD ASSEMBLY AND FRONT PANEL ASSEMBLY
The following procedure describes. the removal and installation of the LK02, LK03 keyboard and
front panel assembly.
7.21.1

Keyboard and Front Panel Assembly Removal

Perform the printer housing removal procedure (Paragraph 7.2.1).

Remove the four (8-32) screws, lockwashers, flat washers, and spacers that secure the keyboard bezel to the cabinet base (Figure 7-41).

Turn the keyboard bezel upside down on a piece of foam or bubble plastic, and remove the
four (8-32) kep nuts that secure the appropriate keyboard to the be zel. Leave the four hex
standoffs in place (Figures 7-42 through 44).

Lift the keyboard off the weld studs, disconnect the appropriate cable connectors from the
keyboard, and set the keyboard aside.

7-45

1...
",

)

I
o

~
'"

II' o l i n
Q

lilA

I"'"

III

IT
lulll' 10
10 IF ill"','llH . J 1II III
I xIII : mv Ul I Jil N III '" ,

~KEYBOARD BEZEL
CP-1558

Figure 7-41

7.21.2
1.

Keyboard Bezel Removal

LKOl Keyboard Assembly Installation
Reconnect the appropriate cable connectors to the new keyboard (Figures 7-42 through 44).
Place the keyboard on the weld studs and secure with the four (8-32) kep nuts.
CAUTION
1. Ensure that the spacers are placed under the keyboard bezel. Failure to do so may result in damage
to the print head because of interference with the
keyboard connector.
2. Ensure that the indicators on the front panel (if
applicable) are properly seated in the bezel prior
to securing keyboard bezel.

Replace the keyboard bezel on the cabinet base and secure with the four (8-32) screws,
lockwashers, flat washers, and spacers.

Perform the printer housing installation procedure (Paragraph 7.2.2).
7-46

KEYBOARD BEZEL -

_ _.......

STANDOFFS

,+------ LK02 KEYBOARD

J2 CONNECTOR

- 8- 32 KEP NUTS

-------~7'

CP-'S67

Figure 7-42 LK02 Keyboard Removal

7-47

KEYBOARD BEZEL ----~

HEX STANDOFF

LK03 KEYBOARD

~-.--- 8-32 KEP NUT

I
I

~
cp- 1!566

Figure 7-43

LK03 Keyboard R em oval

7-48

2
I

®
RED STRIPE

PAPERL-__~
OUT
TABS
i.

~INSULATOR

•

WASHER

TO EXTENDER BOARD
(IF APPLICABLE)
RED
STRIPE

CP-2103

Figure 7-44

LK03 Keyboard and Control Pad Removal

7-49

POWER BOARD

7.11

The following procedure describes the removal and installation of the power board.
7.11.1

Power Board Removal

Remove the power from the LA36. Remove the printer paper.

Open the rear access door to the cabinet.

Disconnect the connectors from the jacks, and the quick-disconnects from + 5 V (red) and
ground (black) on the power board (Figure 7-3). Disconnect the connector from the power
board to the jack on the logic board.

Remove the four (8-32) screws, lock washers, and flat washers, and the two (8-32) hex nuts,
lockwashers, and flat washers that secure the power board to the cabinet. Set the power
board aside.

7.11.1

Power Board Installation

Place the new power board in the cabinet and secure it with the four (8-32) screws, lockwashers, and flat washers, and two (8-32) hex nuts, lockwashers, and flat washers. Torque 832 screws and hex nuts to 16 :::t: 2 in-lb.

Reconnect the connectors to the jacks, and the quick-disconnects to the +5 V (red) and
ground (black) on the power board. Reconnect the connector to the jack on the logic board.

Close the rear access door on the cabinet.

Replace the printer paper and restore power to the LA36.

7-50

7.23 LOGIC BOARD
The following procedure describes the removal and installation of the logic board.
7.23.1

Logic Board Removal

Remove the power from the LA36. Remove the printer paper.

Open the rear access door on the cabinet.

Disconnect the connectors from logic board jacks (Figure 7-3), and the quick-disconnects
from the +5 V (red) and ground (black) on the logic board.

Remove the six (8-32) screws that secure the logic board to the rear access door and set the
logic board aside.

7.23.2 Logic Board Installation

Place the logic board on the standoffs, and secure them with six (8-32) screws. Tighten to
8 ± 1 in-lb.

Reconnect the connectors to logic board jacks, and the quick-disconnects to the +5 V (red)
and ground (black) on the logic board.

Close the rear access door on the cabinet.

Replace the printer paper and restore power to the LA36.

7-51

CHAPTER 8
ADJUSTMENT PROCEDURES AND LUBRICATION

8.1 GENERAL
This chapter contains a detailed description of the following LA36 adjustments.
•
•
•
•
•
•
•
•
•
•

Encoder Adjustment (Paragraph 8.2)
Print Head Adjustment (Paragraph 8.3)
Carriage Shaft Adjustment (Paragraph 8.4)
Print Bar Adjustment (Paragraph 8.5)
Paper Guide and Printer Mechanism Adjustment (Paragraph 8.6)
Paper Out Switch Adjustment (Paragraph 8.7)
Ribbon Tension Adjustment (Paragraph 8.8)
Ribbon Drive Assembly Adjustment (Paragraph 8.9)
Idler Gear Assembly Adjustment (Paragraph 8.10)
Bumper Assembly Adjustment

The print bar and carriage shaft adjustments require exact tolerances and are not recommended as
field procedures.

8.1 ENCODER ADJUSTMENT
The following procedure describes the two encoder adjustments. First. the encoder is adjusted for a 50
percent duty cycle; second, the phase relationship between the two channels is adjusted.
1. Set the POWER switch to OFF and perform the printer housing removal procedure (Paragraph 7.2.1).
2. Set up the scope as follows:
•
•

Volts/Division: 1 V
Time Division: approximately 50 p.s
NOTE
This note applies to printers with cover interlocks.

The cover interlock must be overridden to perform
the following tests. One method of overriding the
interlock is to temporarily tape the interlock switch
down.

8-1

3. Disconnect the wire (servo lead) from the power board to the servo fuse holder (F2).
NOTES
1. Use extreme care to prevent the loose servo lead
from shorting.
2. Ensure that the servo lead removed from the fuse
holder is the one coming from the power board.

Using a test lead connect +5 V from the logic board to the servo fuse holder (F2).
4. Connect scope CHI probe to E6-6 on the M7722 logic board (E2-6 on M7723, EIS-6 on
M772S).
5. Connect scope CH2 probe to E6-S on the M7722 logic board (E2-S on M7723, EIS-S on
M772S).
6. Slip the timing belt off the dc motor pUlley.
7. Restore power to the LA36 (set the POWER switch to ON). The motor will rotate clockwise
as viewed from the front.
S. Select channell, set vertical to CHI, and trigger source to channell.
9. Adjust scope for one duty cycle full scale (Figure S-I). Observe the duty cycle.

r-I

SCOPE DIVISIONS

50%DUTY

CYCLE

MAXIMUM JITTER

10
M-0585

Figure S-I

Encoder 50 Percent Duty Cycle Wave Shape

8-2

to. If the channel 1 signal (Figure 8-1)
does not have a' 50 percent duty
cycle (jitter included), carefully
remove the encoder cover and
adjust R 1 on the encoder assembly
(Figure 7-2).

PHASE ADJUSTMENT SCREWS

11. Check the channel 1 jitter (Figure
8-1). Maximum allowable jitter is
1.4 divisions (or ± 0.7 division).
12. Select channel 2, set vertical to
CH2, and trigger source to channel

2.
13. Adjust the scope for one duty cycle
full scale (Figure 8-1). Observe the
duty cycle.
14. If the channel 2 signal (Figure 8-1)
does not have a SO percent duty
cycle (jitter included), adjust R2 on
the encoder assembly (Figure 8-2).

Figure 8-2

Encoder (Rear View)

IS. Check the channel 2 jitter (Figure 8-1) Maximum allowable jitter is 1.4 divisions (or ± 0.7
division).
16. Set up scope per Figure 8-3.
CAUTION
Exercise extreme caution when adjusting the encoder
to avoid bending or damaging the disk or coming in
contact with the rotating disk.
17. Channel 2 should lead channel 1 by 90 degrees ± 20 degrees (Figure 8-3). If not, loosen the
two encoder screws (Figure 8-2) and reposition the encoder subassembly as required and
tighten the screws.
18. Turn the power off.
19. Glyptal both potentiometers and carefully replace the encoder cover.
20. Remove the test lead between +S V and the servo fuse holder. Reconnect the lead from the
power board to the servo fuse holder.
21. Remove the scope leads and close the rear access door.
22. Reinstall the timing belt on dc motor pulley.
23. Perform the printer housing installation procedure (Paragraph 7.2.2).

8-3

8.3 PRINT HEAD ADJUSTMENT
The following procedure describes the print head adjustment. Having the print head out of adjustment
will result in poor print quality and shortened head life.
I.

Set the POWER switch to OFF.

2. Perform the printer housing removal procedure (Paragraph 7.2.1).
CAUTION
It is possible to set the Carriage Adjustment lever
beyond the minimum gap position. If this is done, the
correct head gap adjustment cannot be made.
3. Set the Carriage Adjustment lever to the minimum gap position (detent closest to the print
bar).
CAUTION
Ensure that the feeler gauge rides between the protrusions on the print head. Do not exert excessive
force on the print head when making the adjustment;
it will cause the carriage shaft to bow, resulting in
more than 0.3048 mm (0.012 inch) of clearance.
4. Place the 0.3048 mm (0.012 inch) flat feeler gauge between the print head jewel and the front
surface of the print bar (Figure 8-4). Check for 0.3048 ± 0.0508 mm (0.012 ± 0.002 inch)
clearance.

8-4

PRINT BAR

PRINT HEAD

0.012
FEELER GAUGE

6-32 SCREWS TO
BE TIGHTENED 10 ± 2
IN./LBS. OF TORQUE

CAUTION
ENSURE THAT FEELER GAUGE IS INSERTED
BETWEEN THE PROTRUSIONS ON THE
PRINTHEAD. FAILURE TO DO SO WILL RESULT
IN IMPROPER CLEARANCE AND SHORTEN
THE LIFE OF THE PRINTHEAD.
7393·06

Figure 8-4 Print Head Adjustment

8-5

5. Move the print head to extreme right or left and check for 0.3048 ::I: 0.0508 mm (0.012 ::I:
0.002 inch) clearance.
NOTE
If the head is aligned properly do not perform the
following steps. Restore the LA36 to its normal operating configuration.

6. Loosen the four (6-32) print head screws.
CAUTION
Ensure that the feeler gauge rides between the protrusions on the print head. Do not exert excessive
force on the print head when making the adjustment;
it will cause the carriage shaft to bow, resulting in
more than 0.3048 mm (0.012 inch) of clearance.
7. Adjust the print head gap with the carriage in the center of travel. Place the 0.3048 mm
(0.012 inch) flat feeler gauge between the print head jewel and the front surface of the print
bar. Push the print head snug against the feeler (Figure 8-4).
CAUTION
Do not apply more than the recommended torque
when tightening the print head screws or the molded
inserts in the carriage assembly may be damaged.

8. Tighten the four (6-32) screws to 10 ::I: 2 in-Ib of torque.
9. Move the print head to the extreme right or left and check for 0.3048::1: 0.0508 mm (0.012 ::I:
0.002 inch) clearance.
10. Replace the ribbon and ribbon spools (Chapter 3).
11. Replace the printer housing on the cabinet base and secure with the eight (6-18) screws and
flat washers.
8.4 CARRIAGE SHAFf ADJUSTMENT
NOTE
The print bar must be in alignment prior to aligning
the carriage shafts.
The following procedure describes the carriage shaft parallelism adjustment.
1. Set the POWER switch to OFF.
2. Perform the printer housing removal procedure (Paragraph 7.2.1).
3. Remove the ribbon and ribbon spools.
4. Push on the spring-loaded ribbon drive to relieve the tension on the timing belt and disengage the belt from the dc motor pulley, carriage, and ribbon drive pulley (Figure 8-5).

8-6

4 (6-321

SCREWS

B
I
0

a..

!il.

PRI NTHEAO.J

Figure 8-5 Timing Belt Removal

5. Set the alignment gauge on the carriage shafts (Figure 8-6) and zero the gauge by rotating
the gauge bezel.
6. Slide the alignment gauge along the total length of the carriage shaft. The maximum deviation along the entire length of the carriage shafts is 0.004, with the two shaft ends being
equal within 0.0015.
NOTE
If the carriage shafts are properly aligned, do not
perform the following steps. Restore the LA36 to its
normal operating configuration.

7. Loosen the two (10-32) Allen-cap screws on the carriage shaft closest to the front of the
LA36. It may be necessary to remove the two timing belt pulleys to gain access to the
carriage shaft Allen-cap screws. Note the location of any shims between the carriage shaft
and the end plate.
NOTE
When rotating the carriage shafts, ensure that the
shims, if any, do not fall or change position.
8-7

PRINTBAR
o

RIGHT HAND
SIDE PLATE
LEFT HAND
SIDE PLATE

10-32
_ ALLEN CAP
SCREW

'0-32J~Ii~~~

ALLEN CAP
SCREW

ROTATE SHAFT TO OBTAIN

t-+--~~=---_ _ _ _ ~A N~~~M~rNfr~Vl:1If~lLONG
CARRIAGE SHAFTS OF 0.004
ALIGNMENT
TOOL

(TOTAL INDICATOR READING)
CP·3007

Figure 8-6 Carriage Shaft Parallelism/Alignment

8. Slide the alignment gauge along the total length of the carriage shafts.
• The maximum deviation along the entire length of the carriage shafts is 0.004 with the two
ends of the carriage shafts being equal within 0.0015. If necessary, rotate the shafts to
obtain these values.
9. Torque the front carriage shaft to 18 ± 2 in-Ib and check the tolerances listed in the above
step. Loosen the front carriage shaft and repeat the above step if necessary.
NOTE
Replace the pulleys if applicable.
10. Insert the belt tension spring between the left-hand side plate and the ribbon drive.

11. Engage the new timing belt on the ribbon drive pulley; push on the spring-loaded ribbon
drive and engage the timing belt on the dc motor pulley and the carriage.
12. Perform the print head adjustment procedure (Paragraph 8.3).
13. Perform the printer housing installation procedure (Paragraph 7.2.2).

8-8

8.S PRINT BAR ADJUSTMENT
The following paragraph describes the print bar adjustment. Upon completion of this procedure, the
print head must be checked for adjustment.
CALIBRATE
BLOCK

GAUGE
ZEROEO

GAUGE

I. Set the POWER switch to OFF.
2. Perform the printer housing removal procedure (Paragraph 7.2.1).
3. Remove the ribbon and ribbon
spools.
4. Calibrate the alignment gauge by
setting the dial to zero with the calibrate block screwed securely in
place (Figure 8-7).

7937-31

Figure 8-7 Alignment Gauge
and Calibration Block

5. Remove the calibrate block from the front of the gauge and set the gauge on the extreme
right of the carriage shafts (Figure 8-8). Record the gauge indication.
6. Repeat the above step with the gauge on the extreme left of the carriage shafts. The gauge
should indicate 0 ± 0.002 with the two end readings being equal within 0.0015.
NOTE
If the print bar is properly aligned, do not perform
the following steps. Restore the LA36 to its normal
operating configuration.
7. Loosen the two hex-heaad 0/4-20) screws with a 7/16 wrench at each end of the print bar
(Figure 7-9). Push the print bar as far back as possible (toward the ribbon chassis).
8. Move the gauge to the extreme right of the carriage shafts. Position the print bar for a zero
indication on the gauge.
NOTE
It is possible to pass through the first zero indication
on the gauge. If this happens, the print bar has been
brought too far forward.
9. Repeat this procedure with the gauge on the extreme left of the carriage shafts.
10. Repeat the above two steps as many times as necessary until the gauge indicates 0 ± 0.002
with the two end readings being equal within 0.0015. Slide the gauge across the full length of
the carriage shafts. The total indicator reading must not vary more than 0.004.
11. Torque the two 7/16 hex-head (1/4-20) screws at each end of the print bar to 75 ± 5 in-lb.
12. Insert the belt tension spring between the left-hand side plate and the ribbon drive.
13. Slip the timing belt on the ribbon drive pulley.
14. Perform the print head adjustment procedure (Paragraph 8.3).
15. Perform the printer housing installation procedure (Paragraph 7.2.2).
8-9

RIGHT
SIDE OF
CARRIAGE
SHAFTS

BAR

+0.0015

-0.001

GAUGE MUST INDICATE 0.004 (TOTAL INDICATOR READING)
ACROSS PRINT BAR WITH THE TWO END READINGS BEING
EQUAL WITHIN 0.0016

ALIGNMENT
GAUGE

7937·31

Figure 8-8

Print Bar Adjustment
8-10

8.6 PAPER GUIDE AND PRINTER MECHANISM ADJUSTMENT
This procedure is performed to ensure the correct spacing for the paper guide and printer mechanism.
1.

Set the POWER switch to OFF.

Perform the printer housing removal procedure (Paragraph 7.2.1).
NOTE
It is not necessary to loosen the four printer mechanism screws when checking the alignment.

Loosen the four (10-32) screws that secure the printer mechanism to the cabinet base (Figure
8-9).

Adjust the position of the printer mechanism (front to back) so that the front surface of the
print bar coincides with the centerline of the reference holes in the cabinet (Figure 8-9).
Tighten the four (10-32) screws to 5 ± 1 in-Ib of torque.

10-32 SCREW

PR.INTER
MECHANISM

PRINTBAR

10-32 SCREW

®
o

G»
0
REFERENCE

:!,--'-,Jr''I;I

81~U~~~~~~~§~~~~~~@J~~~~

-I1---+-t<'H--+ FRONT
COINCIDENT
FACE OF
WITH
PRINTBAR
ClL OF
REFERENCE HOLE

o
10-32 SCREW

Figure 8-9

Printer Mechanism Alignment

8-11

HOLE

Check that the carriage has 0.0508 to 0.1016 mm (0.20 to 0.040 inch) clearance from the
bent-up flange on the cabinet base when the Carriage Adjustment lever is in the minimum
gap position (detent closest to the print bar). If necessary, loosen the four (10-32) screws that
secure the printer mechanism to the cabinet base and redjust the printer mechanism to attain
a minimum of 0.0508 mm (0.020 inch) clearance (Figure 8-10).

Loosen the three (8-32) screws at the bottom of the paper guide and adjust for 2.54 to 3.556
mm (0.10 to 0.14 inch) gap between the paper guide and the bent-up flange of the base
(Figure 8-11).

Replace the paper in the machine but do not feed it up into the tractors. Pull the paper up
through the cabinet and the printer mechanism to ensure that there is no drag on the paper.
Remove the paper from the machine.

Perform the printer housing installation procedure (Paragraph 7.2.2).

0.030 (0.020 TO 0.040) IN. CLEARANCE
BETWEEN FACE OF CARRIAGE
ASSEMBLY AND BENT·UP FLANGE

0.030
FEELER GAUGE

BENT-UP
FLANGE

CARRIAGE
ASSEMBLY

7393-13

ADJUST FOR 0.10 TO O. '" INCH GAP
BETWEEN PAPER GUIDE AND BENT-UP
FLANGE (FLANGE IS PART OF BASEl

Figure 8-10 Printer Mechanism
Adjustment

Figure 8-11

8-12

Paper Guide Adjustment

7937-13

8.7 PAPER OUT SWITCH ADJUSTMENT
This procedure describes the PAPER OUT
switch adjustment.
1.

Set the POWER switch to OFF.

Lift up and remove the printer cover.
NOTE
If the screws cannot be loosened in the
following step, it may be necessary to
reform the switch arm to attain the
adjustment.

Loosen the two (4-40) screws at the
PAPER OUT switch.

Rotate the PAPER OUT switch
counterclockwise (Figure 8-12) until
the switch clicks (transfers). Then
rotate the switch clockwise until the
switch clicks again (transfers back).
Tighten the two (4-40) screws to 5 ± 1
in-lb.

Replace the printer cover.

Restore power.

ARM TO BE FLUSH
AT THIS POINT
AT 2ND TRANSFER
PAPER OUT
SWITCH
7412424

CP-2249

Figure 8-12

PAPER OUT Switch
Adjustment

8.8 RIBBON TENSION ADJUSTMENT
The following procedure first checks the individual spool drag. Then, with the ribbon installed, a
carriage drag test is performed, checking the system drag.
1. Set the POWER switch to OFF.

2. Lift up and remove the printer cover.
3. Remove the ribbon spools and ribbon.
4. Place an empty spool on the side not being driven.
5. Wind a small piece of string or ribbon on the empty spool. Measure the force required to
pull the string in the direction the ribbon normally takes (Figure 8-13). The measured force
should be 113.4 to 170.1 g (4 to 6 oz).
NOTE
If the desired indication is not achieved, it may be
necessary to remove the VFU and takeup bracket
assembly to make the adjustment.
6. Adjust the spool drag by tightening or loosening the adjustment screw, while holding the nut
at the base of the screw. An 1l/32-inch wrench is required to hold the nut.
7. Move the direction changing guide and check the remaining undriven spool for 113.4 to
170.1 g (4 to 6 oz) of tension.
8. Install the ribbon and spools.
8-13

PULL
4 TO 50z
NOTE:
Perform Ihis lesl
one side 01 0 lime

DIRECTION
CHANGING
GUIDE

or--:;;~~~==--J
0

I
I

~~~HOTL /~

o
CP·3011

Figure 8-13

Ribbon Spool Tension Adjustment

9. With the ribbon fully wound on the left spool, the ribbon moving right to left across the face
of the print head and the ribbon grommet starting to pull the reverse sensor to the right, a
pull test on the carriage from the left to right should indicate a pull of no more than
1.5876 kg (3.5 lb) (Figure 8-14). The ribbon should be moving right to left across the face of
the print head when the pull test is made.
Failure to achieve a pull of 1.5876 kg (3.5 lb) maximum could indicate a problem in one of
the following areas:
•
•
•
•
•

Ribbon Path
Carriage Assembly (misaligned or damaged bearings)
Printer Assembly (damaged end plates)
Ribbon Chassis
Ribbon Drive Assembly.

10. Reinstall the printer cover.
11. Restore power.
8-14

RIBBON
IDLER

RIBBON
SPOOL

PRINT HEAD

RIBBON
IDLER

-----~------~----~------~/------------_~/~
o_________ 1
o
~ ___________ I __________

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~I----I

~:)rF'''''·
ro~

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o
o

RIBBON
IDLER

RIBBON
IDLER
CP-1554

Figure 8-14

Ribbon Threading/Drag Test

8-15

8.9 RIBBON DRIVE ASSEMBLY ADJUSTMENT
This procedure describes the ribbon drive assembly adjustment.
1.

Set the POWER switch to OFF.

Lift up and remove the printer cover.

Rotate the ribbon drive pulley on the ribbon drive until the clutch eccentric is at its highest
point.

The ribbon drive pushrod should be at the center of the elongated hole (Figure 8-15). Rotate
the ribbon drive pulley and check the travel of the pushrod to either side of center of the
elongated hole. Travel should be equal on both sides of the centerline.

To adjust for the conditions listed in the above step, loosen the 8-32 upper pivot screw
(Figure 8-16) and move the ribbon drive assembly the required amount.

Tighten the 8-32 screw to 18 ± 2 in-Ib, and repeat step 4.

Replace the cover on the printer.

Restore power to the LA36.

IIUlnIt-1 ~
~

)..

....

«l)

CQ)

H!lli!II'1ffiIL

@II

........

NOTE:

l7
o

Travel of pushrad to be equal an both
sides of the elon9ated hole.
CP-3143

Figure 8-15

Ribbon Drive Adjustment
8-16

PUSH ROD
RETAINING RING

RAISED PORTION
OF PIVOT TAB

COMPRESSION
SPRING

7393-10

Figure 8-16

Ribbon Drive Assembly

8-17

8.10 IDLER GEAR ASSEMBLY ADJUSTMENT
The procedure adjusts the idler gear assembly for the correct amount of backlash.

Set the POWER switch to OFF.

Perform the printer housing removal procedure (Paragraph 7.2.1).
NOTE
It is not necessary to loosen the two idler gear screws
when checking for backlash.

To adjust for minimum backlash,
loosen the two (8-32) screws securing
the idler gear assembly to the side
plate (Figure 8-17).

With the idler gear in mesh with the
stepping motor gear and the tractor
drive gear, adjust the idler gear to
achieve equal depth penetration and a
backlash· of 0.0508 to 0.1778 mm
(0.002 to 0.007 inch) between each
pair of gears (Figure 8-17). (The idler
gear should be free to slide in and
out.) Rotate the gears to check the
backlash in several places.

Tighten the two (8-32) screws to 18 ±
2 in-Ib of torque.

Perform the printer housing installation procedure (Paragraph 7.2.2).

Restore power to the LA36.

LINE FEED

0.002 - 0.007 IN.
BACKLASH AND EQUAL
DEPTH PENETRATION

SCREW

7393-10

Figure 8-17 Idler Gear Assembly

*Backlash is the amount a gear turns prior to turning the gear it meshes with.

8-18

8.11 BUMPER ASSEMBLY ADJUSTMENT
Tighten the screws (Figure 8-18) until the top of the washer is 42.42 mm (1.67 inches) from the side
plate on the left side, and 42.42 mm (1.67 inches) from the side plate on the right side. Center the spring
around the screw.

J.=...

E
0

I(!) I

.8. ~ h

~ lJ]
~

f-!

I!,
=

=
=

]

I,irl::J1Jwlrlil

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~

It:)

~ f""T T

1~1'iiJt

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(42.42 mml

1 f::-

-1.67 In.

Figure 8-18

.........

, 1[

1~""

:oJ

~
L~ ~ I )
~ "-jU
I~

-----

Bumper Assembly Adjustment

8-19

r@l

_J7

@ll
0

1-1.67In.

(42.42mml
CP-3144

8.12 LUBRICATION
The DECwriter is factory lubricated; however, after an extended period of time, lubrication may be
required (oiling should be done infrequently). Table 8-1 lists those areas that may require lubrication.

Table 8-1

Lubrication Points

Area

Lubricant

Amount

Carriage Shafts
Figure 8-18)

DEC Part No.
49-01174, or
Nye Oil No. 622-00

1 or 2 drops in
each oiler

Ribbon Drive
Assembly
(Figure 8-19)

SAE30

1 or 2 drops in
each of the five
places shown in
Figure 8-19

lEFT-HAND
SIDE PLATE

Oil BACK
BEARING
OllON
WASHER
Oil BETWEEN
ROD END AND
ECCENTRIC COil

Oil BACKSTOP
BEARING

ADD 1 DR 2 DROPS
OF DEC49-01174
OR NYE OIL 822
TO EACH OILER

7135-12
7937-35

Figure 8-20

Figure 8-19 Carriage Shaft
Lubrication

8-20

Ribbon Drive Assembly
Lubrication

APPENDIX A
ENGINEERING DRAWINGS

A-I

NOTES:

1. Fuse FIlS .3.A 58 FOR 115 V ,..,ND
I OVT I
1.5ASBFOR 230 v
JI ~U.
2.f>OWER CORD COLORS .ARt!.AS ~OL.L.OW~-_:J

VOLTAISE

1/5 V

5
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A-3

NOTE.S:

I
SEE

TABL~

I. ALL HARDWARE NECE5SARV
TO MOUNT ITEM
AND
ITE.M -3
IS SUPPLIED IN
I
THE OPTIONS KI,_
C:.ITE.M -, IS lNST"LL..£O BY
INSER.TlNG THE Be:NT ENOS
.
of THE ·PAPER BASKET" INTO
.HE 2 HOLES PROVIDED ON
COVER AS SHOWN_

NOTE "2

'"e:

TOP (REF)

H
FLAT WASHER
900~64

TABLE

SUPPOR'-

SRI'. (REF)

LOCK WASHER
!1007~

°10-32 <.75 LG.

SCREW, PAN. HD MACH

9006075 -I

NUT
TABLE

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TOP

(341173..)
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------ - - - - --- -- - - ---l---------

SE11: NOTE -I

TABLE SUPPORT

.-° 10 -" •.75 LG. 9:REW

BRK,

(C-MD-7411'!17C -0-0)

TYPE B SELF nD.
(!1OO~12 -QlI)

VIEW A-A
SCALE: 1/1

33.S
REF

SEE NO,E-I

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(~OOC;'; '32)

LA36

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HE x

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(~OO";255-~)

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A-4

THIS DANtiIfliG ... NO !>PECIFI(;.A,TlONS. HElIEIN, ARE TI-4£

1'III000"TV
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5p,qRE FUNCTiON 2
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12

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l864~ ~3~__________________~/Z~---

II
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f 1::';;

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IltiBAuD

t;I

8TH BIT fVJARKING

15 D¢

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MPCr.

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MPC;;'

BEl. H

LEGEND' <Zl = JUMPER INsERTED
I = JUMPER NOT INSERTED
REV,

CHI(

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,-L-____________:-____1-________-r________JL____-;____________JLIf~------------~-1------------_r-----1--------~---------1~~~~::~----~~~E"~~~~~O~F~8~__~li~-J~1-~-L~~~~~~~
l____________________Jl______r-__________.1__:-______________
3
2
7
6
5

==--

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PRINT MOrlON ( pI¢)
RETURN' MOT/O}./ (". ¢/.(/J • )

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8
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JIOT Il RfPROOUCED 011 COPIEOGI Ust:O IN WHOlEOItI"
PUTlS TH(WIS fOR Tlt(MAfilUfACTURE 01 SALE Of
ITEMS WITHOUT WRrTTfN PUMISSION
COP\1:H'"T@ If'S
DIGITALEQUIPIII[NTCOILPOUTION"

[

NUMBE'R
VAfllATION
~~=-9--=.1 1NQ!'~o"l SIONS FOR EXTERNAL PARITY SWITCH
~ 7 7 2 8 - Y A ~IlPRoVI SIONS FOR EnER~AL PIIRI:Y SWITCH

1-- .JI POWER ~OARD
.12 _ _ Knl'>OARD
J3 _ _ 20MA SERIAL LINE
,j 4- - _ OPTIONAL lNTERFACE PORT
,10, _
cO; EXPANDER cnlON MJUN,ING BOARD

LEGEND

I. CONNECTORS:

NOTES:

A+-

91
92
95

SEE NOTE 2 ,

PI,P2,P3 _PARITY SWITCH
COMPONENTS WITHIN OUTLINE .. OT IN5fRTfD
IN PREFERRED CONFIGURATION
RH DES NOT USED ARE:
CI<,O.C"I.C"2.C"q, Cqf'C'JB,C'l6

TPZ66

U ~

....

MAXIMUM REF DES USED ARE:
\120, R :24, E .. ". C"lB, 014. J<;. CR 1.0.1<;

POST PI, P2 i P3 FOR PARITV SWITCH
CONNECTORS

102 RfF

SPARE'S

17~I04

CINl ~V

4 PLACf5

~3_

P~~
c

Vt7-I03RrF

C99

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F'P-'" - GND
E5;<- '" ~ tSV

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SECT ION

A-A

-*iw

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(VA VARIATION ONLY)

(YA VARIATION ONLY)

-..,
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I

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C/B-eBB

J leW-1~ ~ 1

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Rln

TT~ TP~
IK

+A
8640
LM30lA
1702A
74123
74150
74154
74161
74175
74190
74193
7442
7 ..89
7493
MK2600P

RI21

Ib
16
24
24
16
16
16
16
16

8
8
8
8
8
8
10
12

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RI2QJ
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RII~

TPV~

TP~C

UART

I"
5
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92
93

19
23 (alY 8)

102

--i--\· "" --------I--f------!..-,i-~~
96

QTYl

R£f. DESIGNATION

ETCH IIOMD /1£11.

....
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~:~....:'t:_ !·~H-1r

rl\·,
DArt

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II~

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....
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'Drs'l M7728-0-1
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DEC NO.

TITL[

. II'.

I....,·p~
EIA NO.

PART NO.

~I i ~I i Itla[i]

"'~l·7S"

If:It..~

PARTS LIST

(gii1J

DEC NO.

DESCRIPTION

r( T

SEMICONDUCTOR CONVERSION CHART

FIRST U$(D ON OPTIOH MODEL

IC PIN LOCATIONS

23(QTY 4)LOCATIONS 2.3.5,7 OJIllY

(y), VARIAnO" ONl7)

MSP'£CTlVtl Y EXC£PTIOHS AR£ STATED A80Yt

-,~

GNa AND SY .ME USUALLY PIN 7 AND 14

---

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8
12
12

RIIB

I~r--

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A-21

Cl.T'1/VAk

ClT'l'f'lAR

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ITEM
REF.

DE5IGN~TION

DESCRIPTION

PAR.

NO.

REF. DESIGNATION

ASSY~':.'..'«:. ~~~___ ,-.;;:m;;;---: I, J

f.:R,,:E_F+:RE=F:-+,::;RE:;:F+________ ____ _
REF REF RE.:::.F+_ _ _ _ _ _ _ _ _ _ _ _-+-==.:IIDJ~~l.E:. ECO HISTiI!'I
I-'I-+-,-I-+_.~ _ ____ ___________

•

ETQ£D ClfIlIlT 1IOARJ

_~ 470PF lOOV !i% OIPl'£D MICA

C91

1-"-+-'-I-+_.I'-!-'CI=2_ _ _ _ _ _ _ _ _ _-+...:CAI'=--'2~2IF lOOV 100llYlAR

iJ-f-~~3

3
8

53 s4

Cl7 :~~!r.Cll eel C9II
__
: ~ClI.C83,CI8,C74 C78,Cl9,C92-C9I

-----t-i--!

IODDD24

______

1000037

CAl' D47UF IODY 100llYlAR

e72 C75 C79

5011682
1000010

10D0D51

pAP 25J!U~V AL EL
CAl' ,OIUF IODY DISC

. 3

j 5_

-I

-t-!--I

---f-J!!.~----i-~ _I
1001610·01

------------+----05.07.08,012,014
011DE D864

f-'2~f-..!2-+_,-2

09 010
I - . DC' -- --

DIIDE IN74BA 3 fIN !i% ZENER

_ _ _ _ ..E.'.IDE IN746A :i3v !i% ZENER

~!..I-I-..!.I-+--.!..I ~II
I

___

HOD1I4

1100122

---c--'~I~ ____- ~-:t1

DIIDE MCL1301
DIIDE 1 _

II~D_ - _____{ ~61

~ -'-

2
3

D,!!_____ _
oIIDE 41. ~JAZI 5 IV "ZENER ~'1 _1_1II?~ __ . __
J3,J4
__ _ __
aNI 8 PIN IlATE·N·LOC1(IOJSINOI
1209J4(i·00
JI.J2.J5
--liNt 40 PIN BERG
-- i2"09941 02 - -

RI5

RES 121K

',t " rtF

1305255

R9,RIO

RES 232K~' IS N'

1305424

R21.R25

RES IM~. 5\ CC

1309595

f-,-+-:I-+-:-'+RO':I",7_ _ _ _ _ _ _ _ _ _+.R=.-E:-S-:3.:0::I:::K-:~::I:....:.,I·:_,,_:_:~I::_F-----+~13.11594

~~ __ :-1-+_R2_0_ _ _ _ _ _ _ _ _ _ _-+~RE~S~2::1~5~K~.~I_:_:I~~~M~F-----~13~i-~16~5,~3_-_~~

1I057!E

lXiill_lffl fOR lIE...

'.I

I 19 :

--'-20-1

no.T_-lIi::-:-:-~-_1

TRANSISTOR 045C8
TRANSISTOR MPSA05

1510598
1510705

TRANSISTOR MPSA55

1510706

--t'5~

TRANSISTOR OEC65318

1509338

I C. 7474

1905547

*_
11

m:m:m:~~~.E34,E37,E40

E32 E31 E39E49.E6D.E65_._-t'-I.::.C-'7...:4:::00'-_ _ _ _ _ _ _+1C!9~0:5"_'5~7"_5_ _ _ _ ~

_~~E47,E52,m

2
5

~ C~I_ ~~__.:::-'-:::-:-:~-=::--::-:-,,--+C~R::Y~ST~A~L~I~6!:89~6'_M~H~Zcl.(~II~R~E..!L:~E~AO~S'..!)_+11~8116i9 -. --._=-T&!::: +

E66.ElI
E4.E21.E28.E35,E62

_ _ ~~I __________+:..:19,,0:.:55:.:9,,0 _______ ~ __
I.C. 7493A
190905'
65
I.C-7-4-04----------+·
1909686
__ ~_

~~ __ ~ ~~ _ _ _ _ _ . _____ ~ . .!.4!~~
1901701
____ 62_
I
I
I
Ell
_____ ~c~ _ _. ________ 19019~!... _ _ _ _ f!1
~
3
3 E5 E9.EI1
_ ~.. _ 7.4.!.~~ _ _ _ _ .__ __
19.!.D0I!.._
___ 70
r-'---'--f-I~f-E-2.:.3-------.
I
I
I
E61

7_1_
72

E43

2
5

E14, E29 .-=-::-:-:-=:-.____-+~I.~Cc..'-'7~4.'.:15~0'__ _ _ _ _ _ _ _ j..!11!~-- _____ _
E6,EI2,EII,E42,U4
I.C 7408
1910155

7!..

.-!-.. 1__
2

.....

i 57
151 __
-i.=,

I
10 a2·a6,aI0·a14
3
__ a7,a8,aI5

""3 J -

-------i-cO:-IIDE="'OD66~l---------+ -1100113----- -12

f.-.=.+.:......j...:,..-+~-

ITEM
NO.

1110.

~:~I-':-+_:~ ,~:;:=.~:.C:.~:.~------~~~~SOUF~OO5UF~~=V.:IODY.:AL~:L.:ISC~----~.::oo;00.:::;~~5-----~:~~~

PARl

-a-IIHm28-!'~~.~ -1

CAP39"PiIOOY50. 01PI'ED MICA

Cll,C76.CIO,C97

OESCRI PTION

-=_

2
5

_____ .I_C 7442_ _
I C. 7437

_ __ _

I C 74190

1910046
1910091

1110095

-+::',.:C:.,'.,:L::M::30:,:I.:AN::.,:D_1p_ _ _ _ _ . 19102~ ______ 71

f-::3-+",3_t-:3c-~E",I:.,3~,E..,.'",7:..:,E~2:.,7_ _ _ _ _ _
3
3
3
E3,E36,E41

I C 7419

1910396

~,-t71-~I-,r.E~I~9~~~-------+I~.~C-.~7~4~12~3--------~1~9~10~4~36~---- f--I-

~-t,--~-i~-----------------~~~~------------~~~--------~
I

E55

I C UART

1910459

r2;-t:;2_r.2;-t;E::;6~3~,E~6-7---.-----+_',-:C--:7~4..::11;.:1'-_ _ _ _ _ _ _ _1'1'.!9~10~~6~5,,_0____ . __ -. _ 10
2

E2,EI

I.C.74175

1910651

"w
-

~.:...._ 2 ~~,;;-6:..:,Ec:5.:.1_ _ _ _ _ _ _ _f_'I.-:C-'-...!1:!0!:93~--------+'I,-"9~10,~1~37 .. ______ 12
~ I
I
E59
I.C. 1140
__ ~I!~~. ___ __
1_3..
r--;2;-in2 _t--;2_t-E_I.:.,E_7_ _ _ _ _ _ _ _ _ 1 =C'c'.:S:::OC:::7;5::,',.:4::N,:l6:..,.,.___
__.1911911
14
o 0
I
PROM,17D2A,PROGRAMMED PROMS
2301214
15
o 0
I
PROM,1702A PROGRAMMED PR0t11 - 2301~---~~

t.::

B
4

R67,RI8,R70,RlI

RES IK 11511 CC

R31

RES UK IIfI 511 Q;

--------- -

1300368

1300391
- ----- -f-----------

R37-R43,R53,RI02-RI09,
RES IOK,..,511 CC
130D479
36 :
R1I7, R""I"'O"'O_ _ _ _ _ _+-:=-",...,,,...,..._~=-~_:_.~
I
I
I
RI6
RES 51, OK IIfI " 101lPAI MF
130D5~
37
f--Z--1-':""'t-:
RES 10 11f1511 CC
---- --- ~i3ij---- -f-JI
2
2--1'-Rl=7-:,.--'18

JH;SJ:F

RI3,R22,>l26

RES 180 IIfI 511 CC

1301322

--7s-

R48

RES I1IK IIfI 511 CC

1301327

---f-4O'

RII ,R12

RES 120 IIfI 511 CC

1301775

-41
42

f--.=6'--+....:I'--I...:6=-f-R36=,R54.::=-,-R58--,.~,...7-.~co9,...,-RIO-----1...::.RE::.S~5=,8...:K::.IIfI-:!i%::""::CC:"'--- - - - - - j - 1301874

t~8~jti8=1=8~=t~~~2.~R~75~,R~7~9.~M~I..!..,M5==·~'----4-RE==-S.:~.:K=IIfI~5II~CC~--·------+--13O-2~1-77;·---_-_-- 43
14

RB2-M7.R83,R96,RIIO,RIII,RII3-RII6/RE5. 2K 1/4W 5~ CC

1302388

r-.:..:1--1...:I..:....r.:::I--1.::~:!I==~~~~~.:.:!.:2..::~-(2RE::S~47c=01I~IIfI::!i%:...::CC:2:'-::'.::....::::::..--~...:lii2i91---- 45

t~Z=1=2~=ti2=1~R2~7~,R2;3======-_-_======_.+RE_S__51.,..1....:1IfI...:1.:." IID'iV-riF-ltI55ii:-F-

-liiz41'''----- --46"
-1302.------- --41-RES IUK%!f IlID1lP1'lli-.ti:'F- -i302941----48'

~'_+-I=-f--'-I_+.:M:-----.----+-RE-SlOO1IIIfI!i% CC
I

R18

E53

ROM,MK2627(ALPHA SET,ASCII)

23070A6

r-,~71·-~I,-t.E~4~1-------------------+R~~~,M~K~2~62=6~(N~0~.7SE~T:.,~A~S~C~I~I)~~~2~3~07~I~AI~---------.i

f--'--+--+--+--,---·----E==~:.:.:....:=.::'-'---I~~
f--"-+_I--If--0-+EI5
ROM,MK2628(CONTROL PROGRAM)
230'2"--- ~...: 19
~ 0
I
SCREI.SLOTTEO BIND HD 4,40 .5/1 10D!010'4 _ _ _ =-'0
a 0
I
NUT, KEP 4·40
-. 4
.-4-----·- - - .-- USHER, FLAT, NYLON
..
- --:-..

:~~::;

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2

FASTON TERIIINAL

1007113

AIR

THERIIAL COMPOUND

100.21.

2
7"7

2
7

EYELET (FASTEN _ 1 * )
liRE, INSULATED JUIIPER

15
II

!IOOeI15

CAP ./ UF" 10011

101097B-36

ttl

11'15,111,120

C95
RIOI

1001000

I
I
I
1\£:' a70 '/4'IJ 5~ CC
I!OI9n
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I

£56

Ie 7414

1911324

C99,CI¢¢

CAP J..I.IF 50Y

10109715-3'

loa

POST WIRE WRAP
ruBING T/i/N'WALL Bll/..

9009217

103
104

AIR

910725~

101

REVISIONS

CHK

CHANGE NO.

REV.

M772EHH

A-22

I"t

~,
2..---D...4 5
r=0
I~

1 - PREFERRED-'I

+B
TPK5~

10
.-----------------~----:::-'1140B
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MPC4 CSlb L

12.

X' I
C

74141-

~~4 REG ;' H -~ 02

,~~ I

,--C-cr

EI2

---~C;,RL~-=l'>R"''''--

riPC/\ WU L
1

'O~? NS ~

MPC51,IMUS H

lilI

F3~

2
140

TPY2.1
HZ-+
74:tJ7! 0:1'----,---<-1

9
~

1f1

4 ..-_

MPC4 CSII L

f-i;-

RS"J

T"P,Xb4

-E"

~408
5

1 15

C5;
A8
A7

1 IT

A"-J

9TPX . " r

~
1

__ _

MPC; P,t1B0",

MPC", BMl'>Ii"

I~ 0111
t1PC" eMB~' -I------"

TE'+~t hl..;:"-----------j740~
MPC"> CLK H

H0~

I~ Ab

L----:;-Z0:;"1 A':>

£24

'------,-

2
L _ _ _ _ _---,;-j AI
l - - - - - - - - : - : : 1 " ACIl

~ ~,

II
OCllBI-='0=--_ _ _---,

°0~:,_=8

QTPX2b

pijJ
CIlIUF

It04

1 ___

E21

MPC~ BMB0,

TPH7

C('1

2SUF

QTPX31

~~"~~>--=e--L-I--- MPC3 BI'\B0b

QTPYI7

7404 >-1.:.0_-,-I_ _ _ MPC'!> BMB05
L----'---u E Z I
II

-----1----1---------

L--_ _
TP_f.J.._'I

:::.qwr

>.:.:12=--_I-,-T_P_X_5_1_ MPC '!> BMB04

0,+':>C8

QTPHI
>-'2=---_-'-1_ _ _ MPn I'.MB03

----=-PG""M:7"--,
I 11212 A
1'20

I'l
~A5
i~'0_1 A4

L -_ _

L--_ _--'Z""'-j A,

I
A2
1-------:;-2-1 AI

0i1l8~11-~--------MPC3

~~;7

D0'r:----

""~

MB07
10
0011--'-'9'-+-,,-------- MP C" MB0 (.
Ol!lb
Oli!5 8
01214 7

~
02
+S,IV

"L.-50,I~V
.-t-

MPC 3 MBIi!5
MB(Il4
MPC3 Mflli!3

MPC,

DI1l3~-+_+-+-H._----- MPC3 Melll2

R')

R7B
IK

~ :;,;
A0

~I""

~'1-+_++H+t-r----

Oli!2 <;

"" ~ :~;~ '" "

I
I

~~"=---_-,-

0041---'-7------,

,,"a-tii ;' 00' ~

r -

~ A('

PGM
111212A

L-----:;-2-;l, A4 0:,17 001 .,
A; ffiOM0
_ _ _.,
1-_ _ _ _ _---,I;-1A2
.Jr

f---o TPX41.

Tl'X50

- - - - - - - t-

I'>

I
I
I

I----.J

L -_ _
'7_ A7

MPC; MB00

1
1

1~3_r}4~}4~+_--------+_t_~~----------------~
RIII(1l1-

11-~~~~iI~~~~
III
9+'~V
~ 9~t
r

MPC3 I'IB01

~4~4 ')..:"~_ _ _ ___' 3___1 E32

---

~ I

115 ",~_4

MPC," WU H

B} ~"-'---__,__+-+-+_+_+_--------- MPC; MB02

1'.2

CLR CUP ltJ CON

[02

0:'>

MB0~

B4 ~1~---__,__++++_--_------ MPC"> I'1B03

I G.8: J-

_~ 01 A~~~Sc RI(I)I-':-~f-++-W-t---------j_t-O::T:::P::'X;:;">:-;.,;-----~

MPC3
MPC MB(Il'l

0: ,I 7

f---o-12V

____

MKZi,ZB
EI5
C ROM

VGG

EIZ

MPn bMf.(t1

B">~I

,--------

MPC.3MB07

Bb~~--1.-----__r_+_+---------~u~
__,r_!_+_+_----------

I 20
I~ A3
1
A2

1'1'.

11~0~_ _ _ _ _ __ _ r - + - - - - - - - - - - MPC.3 MB0 ..

BT ~

1 18 A4

MPC4~KIPL
~47~pE\
5,GK
C~=::::'----+=====~r\"ZnI3
I
MPC4 Co.""
L ~ ~~~" EZbh!
1'4
'S"
lPXb"
CI<'
p,nw
9TPX42
2'--1---~r~---;-,r-'i':
-"'~ c, 1~~~1l
C 0'fl-':..!:R_C,~--r
M
~
141~3
1
MPC4 CS04 L ----cL
1'>:0:- 1412;o---'-----~---<-I740P,
El
Mf'r~ E\MB¥,,~ -r--!- 0, Ell R'>Ol 12-----r+-W-t---------j--i-~OT::P::-X::-:4::-:0:--EI~
13
10
EIZ
,,~
'~11JNS (lj-P4
MPC'> BM!'.(f2 -~ 02 PROGRAM RZ(I) ~--rl-+-I--++-------i-t-O=-=T:::P~X~4-::~----~
·c
'rl4~
2
1
_l
3

223 C51
C52

~TPH~ __- - - - - - - - , ,1- _ A~
R? (I) f-"~----T1r_-----_t__t_---'-___=___::

~
Lg'ljcIUPcCLIR'4C~ON4 +1'>

I1 3
1 1'1

-~ 01 Al{?~~~S RI (I)~2----rl+-------i-t-9=-=T:P::-X-::-4:-'>---'
..
I
MPC.4 fi!'G ill H -r-!2 00 4: 1
R0(1)L2"----rl-+li------Hf--'------~

WIPC")+5V
eL,:" K A

CONFICURATION

l ml

MPC4 REG I H

MPCC,

100

TPXII

9TPH4

R";,(I)

PROGRAM

nee

1 10

E,"f,
3 PAl,
B h2..J,.--<1---------,,-,.------;:-;;1
RI
I 22 C50

12 n ''>

N0B,O..::3_ _ _ _-----I
EI2
~
741~3
m:4 REG ',H - - 0; E'l

nO'

MPC 3

MB0 I

J12j~

T_1PY.L.I_~-q1~:'1

C 7 0 ! l -_ _ _ _ _ _

MPC; Me01i!

>,,12=-_-,---1_ _ _ MPn I'.MB01

fT_P_l_"_7_ MPC'> BI'IB(lI0

-:..

')..2=-_---,--

I
_
I

TPX41 ~

I __
L

QTPYI"

'"'''''"''

'""",""",,,"

__ .J

REVISIONS

CHK

REV,

NUMIER

REV.

M7728-0-1

l--~----------~--~-----r----------~~;-------------lr~----------~~--Jl--------,_------~----_s------------~~------------~~------------r_--~L-------:3--------~~~~/==~I~'~--J!SH~.~n~~~~~L--1~~L-L-l--L-L-l~~J-~~~
LA36 MPC

1 ::.~~-

A-23

MPO BI1f'>(»5
MPC'!

C<;I~

ENt'

",R

8.. 03

Mo(l)

1(1)

748~

'-------'-- DZ

E:'>

Me CI) p-9'--_ _ _ _ _ _-+Lf/ _ _

1"1(ll(1)
A~

l'>MI'>(»3

l,_____~;:~-------------I.,__1

--1______+-___--1

b-C:
C

____________

All
IS

J:;

"'PC~ BMf'>QJ5
"'PC~

~~'*_--------------1-'-0--" 02 '~I( ~ k «I) t - ' - - - - . - t - -lr~4 RE 3 2 H
REG

1"11 (Il p-7_ _ _ _ _ _ _. ,_____t -__-Hl~~----------____j1 [I

4
'----100
13

1<~(Il1-7-----I-MPC4nE:; 3H

~OICRAM

12 " "
1

------,---J-~-~-t_+-I~I EI0

riP",; .. U H
Mr:-q -I RIG L
MPC.q 1- I r F I; !..

TTlV:,1

f< I (I) t----.-t-t- MP,_1 HI:G

DI1I

~~4C~N4 crs

LOll

B
MPC4 ZERw fl

+5V

~ 101~~

f<11I(0)It-"--r-t-t-t- -PC4 REG 21 H

TPYI(ll

T;~: P-"~------<J

T~I~

~[I"i,. pJ.>-----"-:-::c-:-------~-u

----r;----~-~-t_+~_____
~~/

+~VR2

~tr4'-----~t~IK~-----~T-P0121

----r+-!-------'---t_+-:~,:':"

I~:

r~::::::::::~o~~~h~
OTP~;'>

TPY'I-

___-r~~-------------L~2~ EI0

S~IP

MPC4

, - - - - - - - - - 0 TP}\ ~ 1

I0;====2 TPXZB
TPXI2

r-----OTPy2~

MPC, BMB QllO

+:~" ~~i~ ~i~ I~
~-

MPC4 REG 2 fl .:; DIS
11
MPC4 REG 3 H -,. 014

~ 013

14150

~ 011

5KIP

~ 012

MPC., HT L

ttl

~ 08
MPC~ PNTABL H ~ 07

I1PO l'>ORROW H

~ ~

MPC7 CARRl' H

~IPC" p,'j L

MUX

~ O~

MPC/o OA H

2!. OIQl
E O~

-T

MPC7 INC fl

-i-

t ~~

MPn CF< H

~IPC4 STEP IF L

MPC4CLRHDEL

• IIi'

~ '3

MPC4 SET HOE L

MPC4 LOAD OIA L

01'1

2~ 03

05
04

-2. 0 I

MPC ~ "-01'J H
0 I
MPC 4- REG I H....!i. DiI'
S; 52

£2

"01

S0
15

I" II~ 114

"p:q CS 12 L

MPC4 -I REG L

91'

9111

EIo'"

MPC4- CS03 L

(bEe I)

b-:....J.--- MPe'! C5112' L (STR I)
2111 O~

MPC4 \lRITE llUFF L

MPO BM!>06

21 02

MPC'! +1 REG l

I'IPC? flillfll1l5

22 01

iIIPC3 !>illfll1l4

2? 00

L~=====~TPYII
TPX1~

p..:'----.--- I1PC4 CSI't l (SKP Z)
I>::~--r~- MPC4 CSQI!> L (!.KP I)

1:>-'--..-11-+- I1PC4 CSIIZ L (eNG4)
I:>-'-T-+ll-+- MPC4 C5IHI L (lIN G I)

L;:r-':::':;T--J
MPC~

cu< L

L-----------~OTPx2~

o-'--'-+t--- (JMP I)
~4J---- MPC4 CSIZ L

TI'1\~2

MPC3 BMBI1J7

+I 0-2=---,r+-H-------- MPC4 elR OA L
-0
I
HPC4 CLR KIIH L
5TI'>0
TPX~0

STflI

5(2'

-.+-____ MPC4 LOAD CIIA l

2'> 011l

MPC4 CLR BEL L

,~ t>-4=--_ _
-2
3

22 01

~ 5 D~
.4 <;

CLK

SET BEL L

(JI'II' 3)
0-1..;5++-,_ _ MPC4 eSI5 L (JI1PZ)

MPC4 SET HOLOL

- B o-'-'-H--'-------- MPC4

~;~~ ~:L: i ~~

I" II'> 14

eHK

I'>

MUX

L-------------~-+_I1--+----------------------------L-~I--Ir-i-----~rr-r~140

'''~

L (JMl'4)

MPC4 CLR Clf'> L

Ie;;

SKIP

~ 0[;

010

OIZ

~ 011

2. 05

~ 00

FUNC
Drl'

1; 14

MI'(:4 REG0 H -:-:- 07

~ 04-

I1PC4 lERO H

STf'>

~ 01)

EI4

E.!. 010

DIS
11
'W-1-<11;-----'----~11l 014

14154
E22 ,15 p.:.1.:,.7~~t-'-

r-<)TPX~"
fl5 o--'-++-!+-HH-~I--,--I -M
MPC4 CLR INIT l

MPC '. flMB0S--=:l9

5TB

MPC," KBH H

~M1PYZQl

TPX24

TPY7
TI''Y5
'-----0 TP X55
' - - - - - Q TP1(%

:~~~I
10

7+(jI4
E?5

14-00'
E"5

8
1:>-=-----+<>+-CHAR lEST L

......

lEV_

LA36 MPC
(MPC4)

M7728-0-1

I(V .

lL_~._==-----8------l-----~--------l-~7~----------,~----------~6~--l-------,-------~---5;----------Llr-----------:-L----------r---~------~3~----~~~r-~/~/----~SH~.~~~~~O~.~__-L~~~~~~~~~~~

A-24

~+">v

RC, ..

.OOSlJF

5.' K

~._

['ID
.0f/.lSUF

TP"'b

H.'

TPX-"

R""

RI (I)
ClR

R52
IK

RECEI''I E

R2(1) 8

4
OPTION CLK L

TPVII

5
4112'

I1H!

4 BIT

RIPPLE
11''>(1)

1·J.8,t.(/J1Z'

TPXB

t5V

CR I

I~B

1/2W

, '01'

RS5
II<'

.,Rn

MPC1 1.IM·U5

~2Ql

Ri1K1l I--=r-l-l-----'--- MPC S I· 184 US H
1

eLk'''' elK I

. - - " " ' ' \ , - - 0 t ~V

(II">

20MA
lOOP

TPY26

7 S

L----'----t---11-~3..a-..._-:l__c12;,--- >'lees CL K H
b-'-~~- MPCS

elK L

TPXS1

t'lV

C"!I

TRAf\JSM 1"1

1'.41
\'50

4J"PF

J2-U JZ-F

FUNCTION
ON

MP(S 4.B KHZ

CZI

ON LINE

LINE

'>!'lOCAl PRINT
LOCAL

R112l
IK.lW
-~-2I1lV

1,1"
.14

1Pli

TP! 7

"TTL REC DATA (s.I.)
L ~ MARK

I
):>-:":""'L-_ !'Ipes

J2
MPC6 KSTE'

~C\J

B
RQl(Jl

DI1l

R I (I)
RZUl
D~

RoO

CLK

I'I'-

13
12.
II

LOCAL L

+">V
MPC"> \.1' KHt

141~1

n'VI4

CSl

• I

·CO

DISABLE L

W.U.

5.l:.

tl2V

E"1
BINAR'f
COUIJTER

+15

MPC"

-12V

CNTEN

~.O.

RS7

t5V
MPC' BREAK + L

TPH5

NOTE: FOR OTHER
JUMPER
TTL DATA TERMINALREAO'f H

FULL !)JPlEX ACllV E

FUll DUPLEX PASYVE
LEGEN\):
CHK

10 JUMPER INSERTED
0 0 JUMPER NOT INSERTED

REV.

TrrLE

~=~~~.-----8------~----~--------~~7~----------~-----------6----~------'-------~---5----

LA36 MPC
MP

NUMIIE.

REv.

M7728-0-1

______~,.----------~~----------r_--~-------3--------~~~LE~~f--~/----~SH~E~~~~~O~f~~~~~~~~~~~~~~

A-25

I,JI() Wil

FU~CTION

1'0[' hl,IC

_Q1H (:.. 1

J
-leV

TABLE m

1-0-8ZLLV'I

1I1Q ... I'IN

M7128-YA-1 ONLY. WIOf "'_II_O_",,_I.,.-T_T_EO
_ _ _ _- ,

..',.)..IT. ,H, "PA..R..ITY., _SW
...Ire
.._H..

~~ r,,~t \N~,

EVI--N r'AR! T 'f

NOH' THE fOLLOWING fABLE APPLI ,5 TO

Wl5

;.lH f\l MI\\,K1N ~

110 £-klf

6
TABLE 11

TABLE I

.v.. J..I T..H_0.,.J.T

PA R I T Y SWIT C H

r--]>-'7"x

I,n"m

H~h

--0

+sv -~

O-r- MPCL r.nEAK t L

".."r

'i'

'wU l

>-+C>+- FurC,ION CliO
c
cD>+___.L...I-o

I',

_'R ERI; f -

FP tRH ~

T~ .. II

TPX2c

RDS~o~----------------------------------,

L ____________~K~E~~4~------------------------------_+_+~2~' ~D4

0-1----.-- - - 1
1'11'1
0-f---.L...-QTPi!ZI2l

KE1 I

r-MPC6

KSTB

flSABLE L

~~.,~:

~TPY2"

f----<:J TPV 1b

D--I----'----c TPV21

KEY

SERIAL

rl--~ LO XD

~~~~ ,;~0-'2,--_--, ~

121
MPCC WU H

p',! f--,~' '0"
I' -

+5V

C9A

150

TJ1)ib5UF

';;rz,- -

I ~--~

5T6 H

I!ilK

t::,V

,- -

>-'~J-'--'''1 C

L-=_ - -

TP~Z1

..IT'

5
,

R"I

I~ E51

12
I

~ES'7

RG,Z

TP'l12

R44

113~

[,
+5V

MPC':> Z0~ H

JE51

7'f1ZI1

f--...o wy"

8"40 2

f-.--------'=cl E S3

B
1'1-01

L....__________________________9~E~'7

i-~(
~
I
J.L--j

--,
P)9

,Ii 10Pllcl~¢
T
I

I 19

11K

"'.;svl
:

.IUF

c9t
Ir
I
~ __ ~u_ _ ~ t-=: _ _ _ _ *J

REV.
TITLE

lL-~

NOTE' :
.. THE FOLLOWING SCHEMATIC
APPLIES TO Ml128-YA-1 ONLY

TPV7

MPC5 1.76 KHZ

liN

Rb'

-+D-I--- MPC~ UART D~TA 1

/>-I:.:.I_+_ _ _

+5VV0-__~I~K~--ru~A~m~E~N~~&~L~E~H~+----_+{)

,..-_ _-, ES7

I~
I 017<101

"J B:~,3

+5"
Rb4

MPCS 4.~ KHZ
8,,4(1\\-0,,-_ _1-,:2,-<
'--_ _ _ _ _ _"'S::,j E5.3
II J141Z11

SPARE FUNCTION I

+SV

330

~ 1 8 1Z1'0 ~8~-+_ _ _--+~+__ I'1PCb UART DATA 2

R9¢

180 :1'> }-",,--+----+-O-~+__ MPC" Ullin DATA 3

~ E51)

L....---.f-,~-- SPARE FUNCTION 2

CHK

TP~4

, I ~,!ilJ3 t-=3=--_+-----!-o-+_ MPCb UART DATA 4

-* J L-= _______ *~

()TPlle.

~E51

L- - - ,
~5V I

11211(

? TPVZ+

11(21 eAUD

III f-'........
~-.-- MPC b KI'>H H

TPVlfl

~~~2 }t-:.:"-+----+D-_!__ ~IPCb UART DATA 5
Ilo~

ESb
-RYJ -,

h i ' '0111
I

7414

., E 30

LcL~-Y~R~D~~~L------------------t_--------------------_+------------------_1__________________________L -__{) TPllj

1474

I
R42

l<1Jib

.-!- 0

~Rm ~2~ ~..IT'
3

MPCb '0.0

EOe ~2=-4---------=5-'-C7:~:

.,. 0
RI24

R46

OUT~'o..°c::.,----'--1

X CLI<
CLR LDC NB2 NBI NP 2SB EP

,--------..-

R41
10K

I TPV2~,

cA»------------'--'VIIIr----C+5V

1Jt{5>,

XD I

MPC4 CLR KBH

TPVIS

~--------K~E=-1~2~------------------------------+_}=-~~1 X02

10J ~~~>, }1-"8'--+_ _ _-+o-+__ l'lPCb UART DATA"

~D31_'1~~---------------------------------------------------------------__,
Ru21_'1~1------------------------------------------------------------~
RDI~I-'-c--------------------------------------------------__,

H13
~
TPl21 I~-----::.:..~~---------------_+_+:,:·~ liD 3

R04~~------------------------------------------------------------------~

L-------~---.e--------~--------------------+-~~XDT
1
,
0-f---.L--QTP<I~
K:c:E=-1~!;;=-~Ob
L __________~K=-E~~5=--_______________________________}_+~~0~ XDS
55
1

~ ~4J,,3 }~"--+----+~+-- MPCb UART DATA 1

RDb~--------------------------------------------------------1

I L _ _ _ _KE~ 1 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _++-::_·l:..j

I ~~

.RD7 ~~.-----------------------------------'

..L...-I-o TP V zeo

~B~J,,~ }l-='-----_+o-t- Mfl:b UART P ERR H

cH»_ _ _

MI1

~ERR ~----------------------------~

?D~~ I'IPC. [,DB

UART OA L

4 ....j [V'
l< Dr,Nf 1_'1-'-'-----,-----.e

1400

CLEAR 011 L

MPC" OA \-\

.-+C>+- BF<EAK-

OPTION DA L

l(l'END: (l- .JUMPfR INSEI\T[l
FOR
I : JLi'lHR NOT IW.\ I 'F lJ
TABLE5 ~. - UON'l CA\<E

NUMtlER

LA36 MPC

M7728-0-1

IUV.

______________-l______r-__________L-______________-,-L________________-J________-;________l -____:-__________-L. .______________~L___________,_----J-----------------~~~L~E~~I--~,~'-----J~sH~E~ET~~~~--~-L=r~~~L-~~~~--L-~~~

•• --

A-26

"THIS a.AWING AND Sl'fC"ICATiONS. HlItIIN, ARt THI
MOI'IIITY 01' DIGITAl. IOUlf'MINT COU'OItATIOH AND
SKN..l NOT • •~II) 011 CO!I'IB) 011 USID IN WHOlJ
(II: IN P.... T AS ,... MSlS 'OIl T. . ~ACTVRE Ol w.I

FRIN''! MQ"[ON

PEll1'!~ 1'.(T1N·~

r~:.:rr~5=AL,,=:=rCOUOlATICIH"

6
~

(0 IC')
(rl(")

. . ___ r - - ~I[,J- t-~r! II

- I _ _ J--~--~

t":'-' I

",'",

t5V (

.S TO I.OV ,.p

1PY~2

C;
RfC INfer-MATION LOAU'O INTO OIA
DIAC+·PRlN1-- RETURI-I MOTION)

~-j

RIB
1't.7 K

I/o~

Rl'G3 REe2 REG I IIEGD
(I) (I) (I) (I)

-DTPYI.,

121

l....-.--MPC11.1B~UC;l

NOMINA L

SPEED (IPS)

-3·B
- 7. b
Rib
5'jK

TP~

MPC~ R~G I H ~ 0:

MPC4 REG III H -

eLK
MPC'f LOAD CVA L

I1PCS W.U. L

RI(I)~

1'.81

Rill (Il >-=2'--__---'___R~8V(.\.__,

NPSA0S

-1"·0

IZI

- Z,," b

-22.B

TPl'O'j

B
I

C5Z

G~
MPS~0S I

ell<

-IS·Z
RIC,
121K
I /0

RI@)~~~__~~__~2VK~__

I<.,(j!~

; 'Yo

.UUF

'f----'----f-o-If- MPC 7 SUM

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DIGIT~ EQUIPMENT COIlPOIiAllON

'.~.(,fIC"'TIONS

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JI LOGIC
FIL TEP CRPS
LINF. VOL r~.JE
EWCOD£F':; CI'IPRlfiGE !{lOTOR
LINE F[£D Me f'i':
Jro - HEIID [fIBLE
2. COMPOOA/C (ITENi 85) TO BE USED OW BOTII
JZ J4 J5 J~

3. "THI~ SIDE up' STICKER TO BE
INSTALLED ON CABLE C~N~ECT()F
PI AS SHOWN.

IN5ULRTORS(lrEIViS 83~ 134) PAID

103
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in. ,'::
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SCALE: NONE
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DESCRIPTION

A-35

P",RT NO

hTEM
INO

THIS DI'CAWING "NO SPEC'~IC"'TlONS, H{REIN "'U THE
PROPERTY Of O'GIT"'l _,)UIPMENT CORPORATION AND
SHALL NOT 8£ IHPROOL ,[0 OR COPIED OR USED IN WHOlE
OR IN PART "" THE dA<,I') FOR TH[ MANUFACTUPf OR YlU

~REF DEoloNATION
QTY

DE,;CRIFTION

HOLE LAYOUT ___

~lfTI

_____

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CAP

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5010806._ ~

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01 THRU 04,07 THRU 010,012
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5510831
1301&95

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1303062

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54

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1110672

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LABEL

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CAP,/lJrD /OOV 20% [)/SC

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53
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WASHER FIBER FlA T
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1300271

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1302465

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1300479

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1301415

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1301.122
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1300426

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DE~CRIPTION

~~~~~~============~============~============~=f~P~A~R~T=N~O~,==~~N~D~,~

1302388

rn
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1305126

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R5,R7,RI2,R15,RI9,R21,
R26, R28, R33 R35, R40, R42
R47,R49

QTY REF DESIGNATION

NO,

RES. 2K 1/4111 5'i.

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1009433

THRU 025,D27 THRU 030,032

R94,R99,R116,R117,R"2

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1105648

DESIGNATION

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REF

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A-36

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D-CS·5"I07.3~-O-l

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ITEM
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SHALL ~T BE REPll.OOUCID OR COPIED OR IJ,$ED IN WHOLE
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A-44

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TITLE

~ri_)~

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sa:'
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ITEM

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LA 36

PART NO

DESCRIPTION

REF DESIGNATION

fiRST USED ON OPTION MODEL

...r.

N"-'E"0·.

"THIS DRAWING AND SPECIFICATIONS. HEREIN. ARE THE
PROPERTY OF DIGITAL EQUIPMENT CORPORATION AND·
SHALL NOT 8£ REPRODUCED OR COPIED OR USED IN WHOlE
OR IN PART AS THE BASIS FOR THE MANUFACTURE OR SALE
Of ITEAAS W!l..HOUI..YIRITTEN PERMISSK>N.
COPYRIGHT ""975. . . DIGITAL EQUIPMENT CORPC,)RATION"

/. SO,"-VENT WELD ENTEf<: KEY:"O :;~ I<E.Y CAP
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3
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NO,

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14 KEY
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7
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WITH Wl INSERTED, LED 05" WILL
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ENG.

0 0
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C-AD-701152S-0-0
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EIA NO.

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SEMICONDUCTOR CONVERSION CHART

A-46

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1/1

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PARTS LIST

S'Z~ltOD~1
~cs
0151.

NUMBLR

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I ReV

COPYR16HT 0 1974 DIGI TAL
roUIP""~IVT CORPOIMTlOIV

3
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NOTES:

MODuLE

I. HE;:JT APPLIED TO QI ;:JND Q2 DURING
SOLDERING SHALL NOT £YCEED 285 0 C
FOI< A PEAIOD OF 15 SECONDS.
2.FIN/SHED HOLE SIZE FOP MOUNTiNG QI AND Q~
SH;:JLL 8£ .078 MIN.,. 083 MA¥.

REF

ECO HISTORY

ETCHED CIRCUIT BOARD
RI, R2

POT£NTfOMETEfR

QI,Q2

PHOTO TP,c A'S ISTOR

10K

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3 IV AND 1<2 MUST 8£ OFV£NT£D AS SHOWN,

WITH NOTCH TOW;:JRO CENTEI'< OF BOI9/?J)

NOTE 3

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RE.F

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II

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r-.:
V;

~ '" ~

REF DESIGNATION

PART NO

DESCRIPTION

TEN
NO

PARTS LIST
ETCH BO.RO REV
I CI
I I I I [ I I I I I I I
QUI PM E NT
~ co ~> f-------+--------ir-------+-----;.;~~1~k~·;:.c:...'/~·-___Ii'~,!o;Ti~~?/~;74
CHK'O. / '
DATE /
.:lEU ~ E'3:c:.~~~.~
.~~~~':!

IIB-a-.

f--------+-------It-------+-----{E;"Ncs.,;.::~_:....-....;..1.=--+.,~"'.~;.,..:.,:..jyr ;TliTLni"E==:;=L::;AT3t6E'::':"---"'-'-'-'-'-'-1 A

I I;:,~§" ~ g~ ~ '" 8 : Q~--t----It------1-------ti~~~~ ENCODE R PC BOARD
~,.~'{I· ~I±"I§;;
en ~ Vii
l~~ 1~~lJ': PHOTOTRAN~ISTOR
1"1". . . 0g> -,D,,'
<t 1\ m ~ g g
NEXT HIGHER A$SY
.-! , , 0 ,
~ -

,
:1

i ' . ~b. m ,,' U ;J;;:

i ,'~I:"-""",

,"'

SIl[I~1

NU..BER

DleSI5411049-0-1

1~.
D

I~~~----------------,------------------------r-------------------------r----------~----------~~~l-lL'~I~I~~S~l-L'~I~UILL'-L~~~~I'~~~-r____S_E_M_IC_O_N_D_U~CT~·o-_R_C_~_N_V_E_R_SI_O_N_CIH_AR_T____~~~~E~~~~
~OF~/ ~~~l~~~~_.L~~[~[l~l~~~~~
~~::. o.
8
I
7
I
6
I
5
f
.4
I
3
I
2
I
1
DEC NO

EIANO

DEC NO

EIANO

A-47

APPENDIX B
ILLUSTRATED PARTS BREAKDOWN

This chapter contains the LA36/35 IPB in its entirety. The page numbering and organization of the
IPB have not been altered for this manual. Additional IPBs can be purchased using the number
appearing in the upper right-hand corner of the following page.
To order send requests to:
Communications Services
Publications Stockroom
Digital Equipment Corporation
444 Whitney Street
Northborough, Massachusetts 01532

B-1

EK-LA36-IP-004

ILLUSTRATED
PARTS
BREAKDOWN

LA36
DECwriter II

HOW TO USE THE IPB
GENERAL
This IPB is compiled following the organization and nomenclature
of the engineering drawing structure.
MAJOR ASSEMBLY LOCATOR
The Major Assembly Locator (fir.;t illustration) is an index that
provides a description and a figure reference for all illustrations used
in this manual.
INDENTED PARTS LIST
This manual identifies each assembly being broken down (figure
reference callout), and all parts of that assembly. Further
breakdown of an assembly is shown by an asterisk (*) preceding the
item callouts in the Description Column. The number of asterisks
preceding an item is used to denote the subordination of that item
with respect to the Major Assembly. A single asterisk preceding an
item description indicates that the item is part of the major
assembly being illustrated. Items that are subordinate to single
asterisks items, are denoted by two asterisks (* *) and immediately
follow the related single asterisk item. Additional asterisks are used,
as required, to denote further subordination. This system of part
identification, provides a means for the user to identify the nex t
higher assembly item and make alternate selections for parts when
the required replacement part or assembly is not immediately
available.
COLUMN CALLOUT DESCRIPTION
Figure & Item - I ndicates the figure number and item number of
each part.

ECO Cut-In - The notation at the top of this column indicates the
ECO level of the system (option), at which the IPS was initially
prepared. Subsequent ECO level designations, that modify existing
parts or add new parts to the device, are inserted in the ECO Cut-I n
column next to the part that is added or modified. A bracket ([)
preceding the item description is used to indicate the parts affected
by ECO's.
Vendor Code/Part No_ - Indicates vendor parts that are not stocked
by DEC. Refer to the Field Service Spares Catalog (vendor part
number to DEC part number) for the vendor code cross-reference.
Used On Code - Letter.; in this column correspond to the variation
codes assigned in Figure 1. Parts with an Alpha notation(s) are used
only in those option variations. A blank indicates that the part is
used on all option variations.
Ref Fig No. - A cross reference between illustrations. F or each
Major Assembly, the number in this column denotes the figure of
the next higher assembly. For all subassemblies, the number in this
column denotes the figure showing additional detailed breakdown.
SYMBOL USAGE
Hardware Designators - Alpha designators for screws (S), washers
(W), nuts (N), and retaining rings (A) are inserted after the item
number callouts on the illustration when stacked item numbers are
used.
Attaching Hardware - The @ symbol is inserted before any part
that is used as attaching hardware. Attaching hardware is denoted as
those parts that are not an integral part of the referenced assembly.

Description Lists the name of the part and pertinent
specifications (when required). Asterisks preceding the description
denote the subordination of the part to the next higher assembly.

(NFR) Not Field Repairable - The (NFR) symbol is inserted after
any assembly that is not to be field dismantled.

DEC Part No. - Lists the DEC part ordering number. A blank in
this column indicates a DEC part number was not assigned at the
time of publication.

Other Symbols - Any other symbols that are required for kits,
accessories, etc., will be explained and appear as part of the item
description.

REVISION HISTORY
ECO LEVEL

PRINTING
3rd Printing

LA36

70-096994

4th Printing

LA36

70-09694

PAGES AFFECTED

DATE

00001-00184
00000-00000

2-18-76

00001 -00251
00000-00000

9-23-76

This 3rd Printing EK-LA36-IP-003

SUPERSEDES 2nd Printing EK-LA36-IP-002

This 4th Printing EK-LA36-IP-004
SUPERSEDES 3rd Printing EK-LA36-IP-003

Copyright © 1974, 1975, 1976 by Digital Equipment Corporation
DEC reserves the right, without notice, to make substitutions and
modifications in the specifications of products documented in this
manual and further reserves the right to withdraw any of these
products from the market without notice.

DEC is not responsible for errors which may appear in the technical
description (including illustrations and photographs) of the products
covered by this manual.
None of the descriptions contained in this manual imply the
granting of any license whatsoever to make, use or sell equipment
constructed in accordance therewith.
Printed in U.S.A.

D.C. MOTOR and ENCODER ASSEMBL Y
Fig. 9
PRINTER MECHANISM ASSEMBLY
Fig. 3
RIBBON CHASSIS ASSEMBLY
Fig. 4
RIBBON DRI VE ASSEMBL Y
Fig. 5

KEYBOARD BEZEL ASSEMBLY
Figs. 12,12A

IDLER GEAR ASSEMBL Y
Fig. 7
CARRIAGE ASSEMBLY
Fig. 6
KEYBOARD BEZEL ASSEMBLY (W/Cursor Control)
Figs. 13, 13A

TRANSFORMER ASSEMBLY
Figs. 8, 8A
CABLE and HARNESS ASSEMBLY
Figs. 10, 11, llA, 14

LA36 DECwriter ASSEMBL Y
Figs.l,lA
CABINET ASSEMBL Y (W/Power Supply)
Fig.2,2A

LA36·01

Major Assembly Locator, LA36 DECwriter /I

1/2

IPB·LA36

31
25
38

11S

12W
25W

21
41
19
20

2S
3W

13
14S
15 W
16 N
11

LA36-0 2

-rer Assembly

Figure 1_ LA36DECW"

IPB-LA36

3
4

FIG
&
ITEM
NO.
1-

DESCRIPTION

ECO
CUT-IN

VENDOR

DEC
PART NO.

lA36
00001

USED ON
CODE

lA36-CA

00165

lA36-CB

00165

lA36-CC

00165

lA36-CD

00165

lA36-DA

00165

lA36-DB

00165

lA36-DC

00165

lA36-DD

00165

CODE

REF
FIG
PART NO. NO.

MODEllA36 DECwriter II
Code A used on lA36-CA
(deleted)
(20 mA Current loop, Numeric Pad, 115V)
Code B used on lA36-CB
(deleted)
(20 mA Current loop, Numeric Pad, 230V)
Code C used on lA36-CC
(deleted)
(20 mA Current loop, Numeric Pad, 115V,
PDP-1O)
(deleted)
Code 0 used on lA36-CD
(20 mA Current loop, Numeric Pad, 230V,
PDP-1O)
Code E used on lA36-DA
(deleted)
(20 mA Current loop, 115V)
Code F used on lA36-DB
(deleted)
(20 mA Current loop, 230V)
Code G used on lA36-DC
(deleted)
(20 mA Current loop, 115V, PDP-1O)
(deleted)
Code H used on lA36-DD
(20 mA Current loop, 230V, PDP-1O)
1

2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18

19
20
21
22
23
24
25

IPB·LA36

"CABINET ASSEMBLY W/POWER SUPPLY
(deleted)
(115V)
"CABINET ASSEMBLY W/POWE R SUPPLY
(deleted)
(230V)
~uide, Paper (deleted)
uide, Paper (added)
"Screw, Phi Pan Hd No. 8-32 x .38
"Washer, Flat No.8
"Washer, lock Split No.8
"PRINTER MECHANISM ASSEMBLY
"Screw, Phi Pan Hd No. 10-32 x .94
"Washer, lock Split No. 10
"Nut, Well No. 10-32
"PRINT HEAD ASSEMBLY (NFR)
"Screw, Phi Pan Hd No. 6·32 x .56
"Washer, lock Int Tooth No.6
"Clamp, Cable
"Tape, Double Coated, .50 Wide
"Screw, Phi Pan Hd No. 4-40 x .38
"Washer, Flat No.4
"Nut, Kep No. 4-40
"KEYBOARD BEZEL ASSEMBLY
"KEYBOARD BEZEL ASSEMBLY
(With Numeric Pad)
"CABLE ASSEMBLY (lA36 Keyboard)
"Jumper (lA36 Keyboard, Not Shown)
"Cable Tie
"Screw, Phi Pan Hd No. 6-32 x .38
"Washer, lock Ext Tooth No.6
"Washer, lock Split No.6
"Washer, Flat No.6

70-09648-01

ACEG

BDFH

00138
70-09648-02
00138
74-11430-00
74-12158-00
90-06037-01
90-06660-00
90-06690-00
70-09696-00
90-08955-01
90-07906-00
90-08896-00
70-09883-00
90-07793-01
90-06633-00
12-02704-00
90-07834-00
90-06011-01
90-06658-00
90-06557-00
70-09750-01
70-09750-02
70-1 0000-00
70-10001-04
90-07031-00
90-06022-01
90-07649-00
90-07801-00
90-06653-00

00052

EFGH
ABCD

12
13

A-H

FIG
&
ITEM
NO.

ECO
CUT-IN
DESCRIPTION

DEC
PART NO_

LA36
00001

VENDOR
USED ON
CODE

CODE

REF
FIG
PART NO. NO.

126
27

28
29
30
31
32
33
34
35
36
37
38

39
40
41

·CABLE ASSEMBLY (BC05F Interface)
·Ribbon Spool (w/Ribbon)
·Ribbon Spool (Empty)
·Clamp, Cable
(deleted)
·Screw, Phi Pan Hd No. 10-32 x .38 (deleted)
·Washer, Flat No. 10
(deleted)
·Nut, Kep No. 10-32
(deleted)
·Connector, P2, Pin Housing, Mate-N-Lok
(Plugs into PB-J5)
·Housing
·Screw, Phi Pan Hd No. 6-18 x .50 (Self Tapping)
·Cover
·Clip, Cover
·Screw, Phi Pan Hd No. 6-18 x.38 (Self Tapping)
·Nameplate (LA36)
·Washer, Buna
(added)
·Jumper
(added)

BC06F-15
36-10558-00
36-10966-00
90-07089-00
90-06071-01
90-06664-00
90-06565-00
12-09340-01
74-11116-00
90-09630-01
74-11122-00
74-11818-00
90-09622·01
36·11826-00
90·09684·00
70·10001·07

ABEF

00052
00052
00052
00052

00053
00052

Accessories/Options
tPaper (Package of 100 sheets)
tBasket, Paper
tTable Top
t8racket, Table Support
tTable Assembly
tWheel Assembly
tWheel, Caster
tBracket, Wheel

74·12103-00
74·12016·00
34·11736-00
74·11972-00
70-09897-00
70-09751-00
74·11826-00
74·11824-00

5 /6

IPB-LA36

mDmDama~
PA RTS LIST

27
29
28

20
21
22
23

29-

(
~,

--t
,
33
32
36

37
38

LA36-02A

Figure 1A LA36

.
Assembly
o ECwrtrer

IPB-LA36

7
4

FIG
&
ITEM
NO.
1A-

ECO
CUT-IN
DESCRIPTION

LA36
00165

VENDOR
USED ON
CODE

CODE

REF
FIG
PART NO. NO.

MODEL LA36 DECwriter II
Code J - Used on Model LA36-CE
(Numeric Pad, Paper Out, 60 Hz 90-132V!
Code K - Used on Model LA36-CF
(Numeric Pad, Paper Out, 60 Hz 180-264V!
Code L - Used on Model LA36-CH
(Numeric Pad, Paper Out, 50 Hz 90-132V!
Code M - Used on Model LA36-CJ
(Numeric Pad, Paper Out, 50 Hz 180-264V!
Code N - Used on Model LA36-DE
(60 Hz, 90-132V!
Code P - Used on Model LA36-DF
(60 Hz, 180-264V!
Code a - Used on Model LA36-DH
(50 Hz, 90-132V!
Code R - Used on Model LA36-DJ
(50 Hz, 180-264V!
Code S - Used on Model LA36-AE (added!
(60 Hz, 90-132V, BELL CANADA!
1

2
3
4
5
6
7
8
9
10
11
12
13
14
15
16

17
18

19
20

DEC
PART NO.

*CABINET ASSEMBLY W/POWER SUPPLY
(115V, 60 Hz!
*CABINET ASSEMBLY W/POWER SUPPLY
(230 V, 50 Hz!
*CABINET ASSEMBLY W/POWER SUPPLY
(115V, 50Hz!
*CABINET ASSEMBLY W/POWER SUPPLY
(230V, 60 Hz!
*CABINET ASSEMBLY W/POWER SUPPLY
(115V, 60 Hz! (added!
*Guide, Paper
*Screw, Phi Pan Hd No. 8-32 x .38
*Washer, Flat No.8
*Washer, Split Lock No.8
*PRINTER MECHANISM ASSEMBLY
*PRINTER MECHANISM ASSEMBLY (added!
*Screw, Phi Pan Hd No. 10-32 x .94
*Washer, Split Lock No. 10
*Nut, Wall No. 10-32
*PRINT HEAD ASSEMBLY (NFR!
*Screw, Phi Pan Hd No. 6-32 x .56
*Washer, Internal Tooth Lock No.6
*Clamp, Cable
*Tape, Double Coated .50 wide
*Screw, Phi Pan Hd No. 4-40 x .38
*Washer, Flat No.4
*Nut, Kep No. 4-40
*KEYBOARD BEZEL ASSEMBLY
*KEYBOARD BEZEL ASSEMBLY (added!
*KEYBOARD BEZEL ASSEMBLY W/CURSOR
CONTROL
*KEYBOARD CABLE ASSEMBLY
*Jumper (deleted!

LA36-CE

LA36-CF

LA36-CH

LA36-CJ

LA36-DE

LA36-DF

LA36-DH

LA36-DJ

LA36-AE

00247

70-09648-01

J, N

70-09648-02

M,R

70-09648-03

L,a

70-09648-04

K,P

00247

J-R
S

3
3

NPaR
S
JKLM

12A
12A
13A

70-09648-05
74-12158-00
90-06037-01
90-06660-00
90-06690-00
70-09696-00
70-09696-01
90-08955-01
90-07906-00
90-08896-00
70-09883-00
90-07793-01
90-06633-00
12-02704-00
90-07834-00
90-06011-01
90-06658-00
90-06557-00
70-09750-01
70-09750-03
70-09750-02
70-11519-00
70-10001-11

00247

See Note 1
00241

11A

IPB-LA36

FIG

ECO
CUT-IN

&
ITEM
NO.
21

22
23
24
25

26
27
28

29
30
31
32
33
34

DESCRIPTION
·Cable Tie
·Connector, (P2) Pin Housing 8 Pin Mate-N-Lok
(Not shown)
·Cable Tie Mount (Not shown)
·Housing
·Housing (added)
·Screw, Phi Pan Hd No. 6-18 x .50 Self Tapping
·Cover
·Cover (added)
·Clip, Cover
·Screw, Phi Pan Hd No. 6-18 x .38 Self Tapping
·Washer, Flat No.6
·Nameplate, LA36
·Nameplate, LAS36 (added)
·Washer, Buna (deleted)
·Jumper

·Spacer, Bezel
·Tubing, Heat Shrinkable
·Tie Wrap, Screw Down
·Clip, Harness
·Fuse Holder (deleted)
·Washer, Ext. Tooth Lock No.8
·Nut, Kep No. 8-32
-Decal, Ground Symbol
·Cable, Paper Out (deleted)
·Jumper, Paper Out (added)
·Tab, Adapter (added)
·Switch, Rework
·Screw, Ph Pan Hd No. 4-40 x 9/16
·Nut, Kep No. 4-40
·Jumper (added)
·Print Window (added)
·Mount, Cable Tie, Adhesive Backed (added)
·Cable Tie (added)
ACCESSORIES
tPaper, Package of 100 Sheets
tRibbon Spool, W/Ribbon
tRibbon Spool, Empty

74-12103-00
36-10966-00
36-10558-00

LABE LS/DECALS (Not Shown)
tSerial No. Tag (added)
tCSA Decal (added)
tLabel, LA36
tLabel, Adhesive Back (RF1 Supression) (added)

36-13210-00
36-13211-00
36-12391-00
36-13088-00

~Jumper

·Decal, CAUTION/WARNING (deleted)

38
39
40
41
42
43

44
45
46
47
48
49
50
51

VENDOR

LA36
00165

USED ON
CODE

00247

J-R
S

00247

J-R
S

CODE

REF
FIG
PART NO. NO.

90-07031-00
12-09340-01
90-07867-00
74-11116-00
74-11116-01
90-09630-01
74-11122-00
74-11122-01
74-11818-00
90-09622-01
90-06653-00
36-1182&'00
36-13249-00
90-09684-00
70-10001-07
70-10001-06
36-12483-00
74-15561-00
74-13675-00
91-07253-09
90-07033-00
90-08340-00
12-11638-00
90-08072-00
90-06563-00
36-12680-00
70-11657-00
70-10001-14
90-09797-00
74-12424-00
90-08033-01
90-06557-00
70-10001-13
12-12009-00
90-08264-00
90-07880-00

I~Decal, LA36 (added)

35
36
37

DEC
PART NO.

00247
00172

J-R
S

00204

00241

See Note 2
00219
00219
See Note 2
See Note 2
See Note 2
00219
00206
00179
00179

J-M
J-M
J-M
J·M
J-M
J-M
J, K
J·M,Q-S

00241
00241
00248

M,R

Note 1: This Assembly no longer installed at this
level. (Per ECO LA36-002051. See Figure
12 A.
Note 2: Items 43, 45, 46, 47 formally installed
under Cabinet Assembly Figure 2. (Per ECO
LA36-OO190)

9/10

IPB·LA36

~D~DDmD\
LlS~/

2j-115V - 2 AMP
MP
23-230V - 2 A

PARTS

305
~
~

f'14

·········.·.\>ir3
,o~J .7~~
15

---

40
41

LA36-03

Figure 2. Cabinet Assembly ( w!Power Supply)

IPB·LA36

FIG
&
ITEM
NO.

ECO
CUT-IN

1
2

DESCRIPTION

DEC
PART NO.

CABINET ASSEMBLY W/POWER SUPPLY (115V)
CABINET ASSEMBLY W/POWER SUPPLY (230V)

70-09648-01
70-09648-02

·Frame Assembly

70-09649-00
90-07601-00
90-09685-00
12-11067-00
12-11067-02
90-09567-00
12-09403-01
12-1 1993-00
90-06046-01

roo" L~""g Id.,,,_,,

3
4
5
6

7
8
9
10
11
12
13
14
15
16

17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47

48
49

IPB·LA36

·Foot, Leveling (added)
·Closure, Tubing (deleted)
Closure, Tubing (added)
·Bumper, Rubber
·Fan, 11 5V (115 CFM) Rotron or IMC
"Fan 11 5V (100 CFM) Torin (added)
"Screw, Phi Pan Hd No. 8-32 x 1.75
(For Rotron or IMC Fan)
·Screw Phi Pan Hd No. 8-32 x .25 (added)
(For Tarin Fan)
·Washer, Lock Split NO.8 (For all fans)
"Washer, Flat No.8 (For all fans)
"POWER CORD ASSEMBLY (11 5V)
"POWER CORD ASSEMBLY (230V)
·Plate, Cover
"Strain Relief
·Strain Relief
·Screw, Phi Pan Hd No. 8-32 x .38
"Washer, Lock Split No.8
·Washer, Flat No.8
"Capacitor (C1) 33,000 MFD
·Capacitor (C2) 18,000 MFD
"Capacitor (C3,C4) 14,000 MFD
·Tie Wrap
"HARNESS ASSEMBL Y, Capacitor
"Bracket, Fuse Mounting (deleted)
·Holder, Fuse
"Fuse, Sio-Blo 2 amp
·Fuse, Sio-Blo 1 amp
"Capacitor (C5).1 MFD 1000V (deleted)
"Screw, Phi Pan Hd No. 6-32 x .38 (deleted)
"Nut, Kep No. 6-32 (deleted)
·Jumper
"Jumper
"Jumper
"TRANSFORMER ASSEMBLY
"POWER BOARD ASSEMBLY (LA36)
"LOGIC BOARD ASSEMBLY
"Door, Cabinet
"Bushing, Snap-in Nylon
"Bushing, Nylon
"Screw, Hex Cap Hd No. 3/8-16 x 1.0
"Catch, Door Strike
"Catch, Door Latch
"Jumper (11 5V)
"Jumper (230V)
"Strap, Ground (added)
"Nut, Kep. No. 8-32 (added)
"Decal, Fuse (added)
"Filter, EMI (added)
"Jumper (added)
"Cover, EMI Filter (added)
"Washer, Lock Ext Tooth NO.8 (added)
"Grommet, Rubber (added)

90-06035-01
90-06690-00
90-06660-00
70-09673-00
70-09673-01
74-11607-00
90-08509-00
90-09572-00
90-06037-01
90-06690-00
90-06660-00
10- 1 1545-00
10- 1 1643-00
10-10187-00
90-09350-00
70-09895-00
74- 1 1925-00
12- 1 1638-00
90-07216-00
90-07212-00
10-00034-00
90-06022-01
90-06560-00
70- 10001 -01
70- 10001 -02
70- 10001 -03
70-09779-00
54-10805-00
M7722
74-11120-00
90-09561-00
90-09565-01
90-08922-09
90-09571 -00
90-09571-01
70-09905-01
70-09905-02
90-06990-00
90-06563-00
74-13384-00
12-12003-00
70-10001-04
74-1 3286-00
90-08072-00
90-07013-00

LA36
00001

VENDOR
USED ON
CODE

ACEG
BDFH

CODE

BEF
FIG
PART NO. NO.

1
1

00059
00059

00055

ACEG
BDFH

10
00052
ABCDEFGH
BDFH
00052
00052
00052

ACEG
BDFH
00021
00021
00052
00052
00052
00052
00052
00052

mamaama\
LlS~/
PARTS

55
56
57
585
59N

65
7W

5
65
7w

--,,,---45

48
49

14 15

~~:~--9

LA36-03A

Figure 2A Cabinet Assembly W/Power Supply

IPB-LA36

FIG
&

ECO
CUT-IN

ITEM
NO.

2A-

1
2

DESCRIPTION

CABINET ASSEMBLY W/POWER SUPPLY 115V
(deleted)
CABINET ASSEMBLY W/POWER SUPPLY 115V
60Hz (added)
CABINET ASSEMBLY W/POWER SUPPLY 230V
(deleted)
CABINET ASSEMBLY W/POWER SUPPLY 230V
50 Hz (added)
CABINET ASSEMBLY W/POWER SUPPLY 115V
50 Hz (added)
CABINET ASSEMBLY W/POWER SUPPLY 230V
60 Hz (added)
CABINET ASSEMBLY W/POWER SUPPLY 115V
60 Hz (added)

70-09648-01

*Frame Assembly

70-09649-00
70-07601-00
90-09685-00
12-11067-00
12-11067-02
90-09567-00
12-09403-01
12-11993-00
12-12581-02
90-06046-01

roo" .....",.

(do...."
*Foot, Leveling (added)
*Closure, Tubing (deleted)
*Closure, Tubing (added)
*Bumper, Rubber (deleted)

3
4
5

r'"

10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31

115V " 15 eFMI

R."., ., 'Me (d.,,,,,,,

*Fan, 115V (100 CFM) Torin (deleted)
*Fan, 115V (35 CFM) (added)
*Screw, Phi Pan Hd No. 8-32 x 1.75 (For Rotron)
(deleted)
*Screw, Phi Pan Hd No. 8-32 x .38 (added)
*Washer, Split Lock No.8
*Washer, Flat No.8

7
8
9

DEC
PART NO.

rOWER CORD ASSEMOLY "15vl (d.,...dl
*POWER CORD ASSEMBLY (120V) (added)
*POWER CORD ASSEMBLY (230V) (deleted)
*POWER CORD ASSEMBLY (230V) (added)
*Plate, Cover
~Strain Relief (deleted)
*Strain Relief (added)
*Strain Relief
*Capacitor, 33,000 MFD
bcapacitor, 18,000 MFD (deleted)
Capacitor, 37,000 MFD (added)
*Capacitor, 14,000 MFD
*Cover, Capacitor (added)
*Spacer, Aluminum No.1 0-32 x 3/8 x 3.00
(added)
*Screw, Phi Pan Hd No.1 0-32 x .50 (added)
*Washer, Split Lock No. 10 (added)
*Washer, Flat No. 10 (added)
*Tie Wrap
*HARNESS ASSEMBLY (Capacitor)
*Bracket, Fuse Mounting (deleted)
*Fuse Holder
*Fuse, Sio-Blo 2 amp
~Fuse, Sio-Blo 1 amp (deleted)
Fuse, Sio-Blo, 1.5 amp (added)
*Decal, Fuse, LA36
*Fuse, Sio-Blo 3 amp
*Capacitor,.l MFD, 1000V (deleted) .
*Screw, Phi Pan Hd No. 6-32 x .38 (deleted)
*Nut, Kep No. 6-32 (deleted)

IPB-LA36

70-09648-01

LA36
00118

00138

70-09648-02

VENDOR
USED ON
CODE

CODE

REF
FIG
PART NO. NO.

ACEG

BDFH

70-09648-02

00138

70-09648-03

00138

70-09648-04

00138

70-09648-05

00247

90-06037-01
90-06690-00
90-06660-00
70-09673-00
70-09673-00
70-09673-01
70-11045-00
74-11607-00
90-08509-00
90-09678-00
90-09572-00
10-11 545-00
10-11643-00
10-1 0426-00
10-10187-00
74-15114-00
90-06881-00
90-06073-00
90-07906-00
90-06664-00
90-09350-00
70-09895-00
74-11925-00
12-11638-00
90-07216-00
90-07212-00
90-09740-00
74-13384-00
90-07218-00
10-00034-00
90-06022-01
90-06560-00

00059
00059
00118

00142
00142
00164

00138
00138

ACEG
JNLOS
BDFH
MRKP

00164

00138
00164
00164
00164
00164
00164
10
00052

00138

MRKP
JNLOS

00052
00052
00052

FIG

ECO
CUT-IN

&
ITEM
NO.
32
33

34
35

37
38
39
40
41

42
43
44
45

46
47

49
50
51
52

53
54
55
56
57
58
59
60
61
62
63
64
65

66
67
68
69
70
71
72

DESCRIPTION
GJumper, (deleted)
-Jumper, (added)
-Jumper, (deleted)
-Jumper, (edded)
-Jumper, (added)
~Filter, EMI (added)
-Filter, EMI (deleted)
-Filter, EMI (edded)
-Cover, EMI Filter (added)
-Grommet, Rubber (added)
-Washer, External Tooth No.8 (added)
-Nut, Hex No. 8-32 (added)
[spacer, No.8 x .75 (added)
-Spacer, No.8 x .75 (deleted)
·Spacer, No.8 x 1.00 (added)
-Washer, Internal Tooth (added)
·Grommet (added)
·Grommet (added)
[TRANSFORMER ASSEMBLY (deleted)
-TRANSFORMER ASSEMBLY 60 Hz (added)
·TRANSFORMER ASSEMBLY 50 Hz (added)
·Power Board Assembly

[Log" Boo,. '--."

(dol.... '
·Logic Board Assembly (deleted)
·Logic Board Assembly (added)
·Logic Board Assembly (added)
·Jumper, 110V
• Jumper, 220V
·Clip, Harness (added)
-Grommet (added)
·Ground Strap (added)
·Nut, Kep No. 8-32 (added)
·Tubing, Heat Shrinkable (added)
-Cable, Paper Out
-Switch, Rework
-Paper Guide
·Screw, Phi Pan Hd No. 4-40 x 9/16
·Nut, Kep No. 4-40
·Foam, Protective
*Door, Cabinet
·Bushing, Snap in Nylon (deleted)
·Bushing, Nylon (deleted)
-Screw, Hex Hd Cap No. 3/8·16 x 1.0 (deleted)
·Pivot, Door (added)
·E·Ring, External (added)
·Screw, Special (added)
·E-Ring, External (added)
·Catch, Door Strike
·Catch, Door Latch
-Decal, Ground (added)
·Fuse Holder (added)

DEC
PART NO.
70-10001-04
70-1 000 1.()8
70-10001-02
70-10001-12
70-10001-11
"2-12003-00
12-12003-00
12-12877-00
74-13286-00
90-07013-00
90-08072-00
90-06561-00
90-07868-00
90-07868-00
90-09285-00
90-08292-00
90-09718-02
90-09718-03
70-09779-00
70-09779-01
70-09779-02
54-10805-00
M7722
M7723
M7728
M7728-YA
70-09905-01
70-09905-02
9O.()8340-O0
90-07018-00
90-06990-00
90-06563-00
91-07253-09
70-11657-00
74-12424-00
74-12158-00
90-08033-01
90-06557-00
74-14144-00
74-11120-00
90-09561-00
90-09565-00
90·08922·09
74-15068-00
90-09773·00
74-15067-00
90-09772-00
90·09571·00
90·09571·01
36-12680-00
12·12893-00

LA36
00118

VENDOR
USED ON
CODE

CODE

REF
FIG
PART NO. NO.

00139
00139
00177
00161
00052
00218
00052
00052
00052
00163
00163
00225
00156
00156
00156
00138
00138

A-H
JNKPS
MRLO

8
8A
8A

00103
00135
00247

J-R
S
JNLOS
MRKP

00162
00162
00162
00162
00161
See Note
See Note
See Note
See Note
See Note

00164
00164
00164
00164
00164
00164
00164

00162
00177

IPB·LA36

FIG
&
ITEM
NO.
73
74
75
76

ECO
CUT·IN
DEC
PART NO.

LA36
00118

·Spacer. Fuse Holder (added)
·Clip Enclosure (added)
·Cover. Transformer Opening (added)
·Washer. Flat (added)

74-15374-00
74-17011-00
74-17012-00
90-07983-00

00177
00244
00244
00244

tLabel. Fuse Rating (Not Shown)

74-12548-00

DESCRIPTION

VENDOR
USED ON
CODE

CODE

REF
FIG
PART NO. NO.

Note: Items 55. 56. 57. 58. 59 no longer installed
at this Assembly Level. (See Figure 1A. Per
ECO LA36-00190.l

IPB·LA36

mamaama\
PARTS LIST;

34~
1

LA36-07A

Figure 3 Printer Mechanism A ssembly (Sheet 1 of 2)

IPB-LA36

LA36-07B

Figure 3

IPB-LA36

Printer Mechanism Assembly (Sheet 2 of 2)

FIG
&
ITEM
NO.

PRINTER MECHANISM ASSEMBLY
PRINTER MECHANISM ASSEMBLY (added)
1
2
3
4
5
6
7
8
9

10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44

DESCRIPTION

·Plate, Side (LH)
·Plate, Side (RH)
·Shaft, Tractor Drive
·Shaft, Tractor Support
CTRACTOR ASSEMBLY (RH) (deleted)
·TRACTOR ASSEMBLY (RH) w/Lock (added)
"Shaft, Screw (deleted)
C·Retaining Ring (added)
"Retaining Ring (deleted)
·Screw, Tractor Lock (added)
CTRACTOR ASSEMBLY (LH) (deleted)
·TRACTOR ASSEM8L Y (LH) w/Lock (added)
·Washer, Flat No. 10 (deleted)
·Bushing, Tractor Shaft Retaining
·Retaining Ring
·Retaining Ring Push-on
·Retaining Ring (deleted)
·Retaining Ring Prong Lock
·Collar, Side Plate
·Hub, Clutch
·Gear, Drive Clutch
·Washer, Clutch
·Knob, line Feed
·Spring, Compression
*Retaining Ring
• Adapter, line Feed
*Retaining Ring (added)

~Sp';"',
Com",..."" I...""
·Spring, Compression (deleted)
*Washer, .697 00 x .375 10 x .062 (added)
·Washer, .697 00 x .375 10 x .062 (deleted)
*Screw, Nylock 6-32 x.50 (deleted)
*Screw, Phi Pan Hd No. 6-32 x .38 (added)
*Washer, Flat No.6
·Washer, Int Tooth Lock No.6
*Shaft, Carriage
*CARRIAGE ASSEMBLY
*Bushing, Plain
[PRINT 8AR ASSEMBLY (deleted)
*Print Bar (added)
*Pivot, Lower
*Ratchet, Pivot
·Screw, Phi Pan Hd No. 8-32 x .38
*Washer, Split Lock No.8
*Washer, Flat No.8
*RIBBON CHASSIS ASSEMBL Y
·Retaining Ring
*Frame, Ribbon Idler w/Bushing
*Retaining Ring
·Washer, Flat No. 10
*Washer, Split Lock No. 10

DEC
PART NO_

70-09696-00
70-09696-01
74-11028-01
74-11028-02
74-11075-00
74-11076-00
70-09693-03
12-11662-05
74-11908-00
90-09582-00
90-09582-00
74-14433-00
70-09693-04
12-11662-04
90-06664-00
74-11425-00
90-09579-00
90-09257-00
90-07975-00
90-09581-00
74-11098-03
74-11441-00
74-11440-00
74-11443-00
74-11437-00
90-09592-00
90-09580-02
74-12535-00
90-09644-00
12-12353-00
12-12353-00
90-07858-00
90-07858-00
90-09591-01
90-06022-00
90-06653-01
90-06633-00
74-11033-00
70-09692-00
74-11108-00
70-10683-00
74-11072-00
74-11439-00
74-11103-00
90-06037-01
90-06690-00
90-06660-00
70-09689-00
90-09580-00
74-11576-00
90-09273-00
90-06664-00
90-07906-00

ECO
CUT-IN
LA36

VENDOR

00001

USED ON
CODE

00247

A-R
S

CODE

REF
FIG
PART NO. NO.

1.1A
1A

00173
00173
00039
00173

00173
00028

00028

00028
00154
00173
00154
00173
00028

00188

IPB·LA36

FIG
&
ITEM
NO.

ECO
CUT-IN
DESCRIPTION

DEC
PART NO.

VENDOR
USED ON
CODE

CODE

REF
FIG
PART NO. NO.

345

46
47
48
49
50
51
52
53

54
55
56
57

58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83

IPB·LA36

-Screw, Socket Hd Cap No. 10-32 x .50
-Spring, Compression
-Nut, Lock No. 8-32
-Screw, Socket Hd Cap No. 8-32 x 1.00
-Spring (added)
-Wick (added)
-Reservoir, Oil (added)
-DC MOTOR and ENCODER ASSEMBLY
CBelt, Timing (deleted)
-Belt, Timing (added)
-Retainer, Bumper Spring
-Spring, Carriage Bumper
-Screw, Phi Pan Hd No. 10·32 x 2.00
-IDLER GEAR ASSEMBLY
-Shaft, Idler
-Standoff, Hex .620
-Washer, Flat No.8 x .062
*Stepping Motor, 16 V DC
-Nut, Kep No. 8-32
*Screw, Hex Hd Machine No. 1/4-20 x .62
*Washer, Split Lock No. 1/4
*Washer, Flat No. 1/4
*RIBBON DRIVE ASSEMBLY
*Spring, Compression
*Ground Strap
*Decal, Ground Symbol (added)
*Nut, Kep No. 6-32
*Speaker, 2·1/2 in. Perm Magnet
*Screw, Phi Truss Hd No. 10-32 x .50 (added)
*Washer, External Lock No. 10 (added)
*Nut, Hex No. 10 (added)
*Bracket, Cover Interlock (added)
*Switch, Interlock (added)
*ROTARY SWITCH ASSEMBLY (added)
**Rotary Switch (added)
**Terminal, Quick Disconnect (added)
*Decal, Parity (added)
*Knob, Black (added)
*Clamp, Cable 1/4 (added)
*Screw, Phi Pan Hd No. 6-32 x .50 (added)

90-0634fX>8
90-09673-00
9~1-OO

90-07988-08
74-13699-00
74-13698-00
74-13672-00
70-09691-00
12-11583-00
12-11583-01
74-11412-00
74-11816-00
90-06081-01
70-09694-00
74-11575-00
90-09583-00
90-06662-00
12-11563-00
90-06563-00
90-06242-09
90-07797-00
90-06676-00
70-09690-00
90-09578-00
70-10001-05
36-12680-00
90-06560-00
12·10299-00
90-06073-03
90-07651-00
90-06564-00
74-15802-00
12-12255-01
70-1 2781-00
12-13187-00
90-07655-01
74-16535-00
12-10114-00
90-07081-00
90-06024-00

00082
00082
00082
9
00155

00226

00166

00189
00189
00189
00220
00220
00251
00251
00251
00251
00251
00251
00251

S
S
S
S
S
S
S

~amaDma\
LIST/
PARTS

0--

@r-14

LA36-09A

Figure 4. Ribbon Chassis Assembly

IPB-LA36

FIG
&
ITEM
NO.

1
2
3
4
5
6
7
8

9
10
11
12
13
14
15

DESCRIPTION

DEC
PART NO.

RIBBON CHASSIS ASSEMBL Y

70-09689-01

·Chassis, Ribbon w/lnserts
·Base Assembly, Ratchet
·Spring, Upper Pawl
·Spring, Main Pawl
·Pivot, Ratchet
·Washer, Ratchet
·Screw, Phi Pan Hd No. 8-32 x .31

70-09680-00
70-09697-00
74-11105-00
74-11 090-00
74-11103-00
74-11061-00
90-06036-01
90-06634-00

Cw...~.

Lock '"' Too," No .•

'd.,..""

·Washer, Split Lock No.8
·Washer, Flat No.8
·Guide, Shoe
*Screw, Phi Pan Hd No. 8-32 x .38, Self Tapping
·Collar, Side Plate
*Disk, Friction

90-06690-00
90-06662-00
74-11419-00
90-09586-01
74-11098-02
74-11405-00

*Wheel, Ratchet
*Driver, Spool
Gspring, Compression (deleted)

74-11432-00
74-11048-00
90-09584-00

*Spring, Compression (added)
·Washer, Brake (deleted)

12-12353-00
74-11106-00

*Retaining Ring (deleted)

90-09580-00

19
20
21
22

* Interposer, L.H.
• Interposer, R.H.
*Spring, Interposer

74-11058-01
74-11058-02
74-11087-00
90-06707-00

G''''~' FI.. No. 6 'd.,.... ,

23
24

·Washer, Flat No.6 (added)
·Washer, Flat No.6 (deleted)
*Washer, Flat No.6 (added)
*Sensor, Reverse
*"U" Clip (added)

90-06634-00
90-06634-00
90-06707-00
74-11060-00
90-09748-00

25
26

·Cap, Standoff Spool
·Screw, Phi Pan Hd No. 8-32 x 2.75 (added)

74-12976-00
90-06050-01

·Washer, .687 x .375 (added)

90-07858-00

·Washer, .625 x .200 (added)

90-06668-00

*Nut, Elastic Stop No. 8-32 (added)

90-09061-00

IPB-LA36

ECO
CUT-IN
70-09689
00001
LA36
00213

VENDOR
USED ON
CODE

CODE

REF
FIG
PART NO. NO.
3

LA36
00113

LA36
00083

LA36
00116
LA36
00079
LA36
00079

LA36
00113
LA36
00186
LA36
00143
LA36
00083
LA36
00083
LA36
00083
LA36
00083

FIG

&
ITEM
NO.
5-

DESCRIPTION
RIBBON DRIVE ASSEMBLY

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16

·Bracket, Ribbon Drive
·Bearing, Salf Aligning
·Shaft, Ribbon Idler
·Ribbon Eccentric, w/Clutch
·Rod, End
·Bearing
·Screw, Soc Hd Cap No. 4-40 x .12
·Screw, Phi Pan Hd No. 8-32 x .31
*Nut, Kep No. 8-32
[*PUlley, Timing (deleted I
*Pullev, Timing (added)
*Clamp, Collar
*Screw, Soc Hd Cap No. 6-32 x .38
*Nut, Hex No. 6-32
*Pushrod
*Retaining Ring
*Washer, Eccentric
*Spring, Backstop

DEC
PART NO_

ECO
CUT-IN
LA36
00001

VENDOR
USED ON
CODE

CODE

70-09690-00
74-11113-00
12-11649-00
74-11068-00
74-11578-00
74-11084-00
12-11650-00
9O-09651..()8
90-06036-01
90-06563-00
74-11035-02
12-12446-00
74-11124-00
90-08045-08
90-08957 -00
74-11046-00
90-09580-00
74-11123-00
74-11426-00

REF
FIG
PART NO. NO.
3

00155

LA36·08A

Figure 5. Ribbon Drive Assembly

23/24

IP8·LA36

FIG
&
ITEM
NO.
S-

DESCRIPTION

DEC
PART NO.

CARRIAGE ASSEMBLY

70-09692-00

1
2
3
4

-Carriage
-Lever, Carriage Adjustment
-Bushing, Eccentric
-Idler, Carriage Ribbon, w/ldler

74-11109-00
74-11110-00
74·11107-00
74-11577-00

5
6

*Washer, Flat No.6
*Retaining Ring

90-06653-00
90-08528-00

ECO
CUT-IN
70-09692

00000

VENDOR
USED ON
CODE

CODE

REF
FIG
PART NO. NO.
3

LA36
00011

6~
I

4-{9
I

LA36-12

Figure 6. earriaQe Assembly

25/26

IPB-LA36

mamaama\
LlS~/
PARTS

OLD DESIGN

NEW DESIGN

LA1BO-13

Figure 7- Idler Gear A ssembly

IPB-LA36

FIG

&
ITEM
NO_
7-

DESCRIPTION

DEC
PART NO.

I DLER GEAR ASSEMBLY

70-00694-00

1
2
3

*Bracket, Gear
·Gear, 48 Tooth
*Tube, Idler (deleted)

74·11420-00
12-11656-00
74-11424-00

*Screw, Phi Pan Hd No. 8-32 x 1.00 (deleted)

90-06043-01

*Washer, Flat No.8 (deleted)

90-06666-00

*Washer, Split Lock No.8 (deleted)

90-06690-00

*Nut, Hex No. 8-32 (deleted)

90-06561-00

·Standoff, Gear (added)

74-16219-00

·Screw, Phi Truss Hd No. 8-32 x 1/2 (added)

90-06039-03

*Washer, Flat No.8 (added)

90-06668-00

·Washer, External Tooth No.8 (added)

90-08072-00

IPB·LA36

ECO
CUT-IN
70-09694

00000

VENDOR
USED ON
CODE

CODE

REF
FIG
PART NO. NO.
3

LA36
00223
LA36
00223
LA36
00223
LA36
00223
LA36
00223
LA36
00223
LA36
00223
LA36
00223
LA36
00223

FIG

&
ITEM
NO.
81
2
3
4
5
6
7
8
9
10

ECO
CUT-IN

VENDOR

DEC
PART NO.

LA36
00001

USED ON
CODE

TRANSFORMER ASSEMBLY (deleted)

70-09779-00

00138

A-H

*Power Transformer (deleted)
*Connector (P3) Pin Housing, 8 Pin Mate-N-Lok
*Terminal, Pin Contact
*Terminal, Quick-Connect (deleted)
*Terminal, Quick-Connect (deleted)
·Connector (J1) Free-Hanging, 4 Socket
Mate-N-Lok (deleted)
*Terminal, Socket Contact (deleted)
*Connector (J2, J3) Socket Housing AMP
(deleted)
-Terminal, Socket Contact (deleted)
·Terminal, Ring Tongue

16-11482-00
12-09340-01
12-09378-00
90-07919-00
90-07917-00
12-10821-04

00138

12-09379-00
12-10820-01

00124
00124

12-10820-02
90-07928-00

00124

DESCRIPTION

CODE

REF
FIG
PART NO. NO.
2

00052
00124
00124

LA36-06

Figure 8. Transformer Assembly

29/30

IPB·LA36

FIG

&
ITEM
NO.
SA-

DEC
PART NO.

DESCRIPTION
TRANSFORME R ASSEMBLY
Transformer Assembly (60 Hz)
Transformer Assembly (SO Hz)

ECO
CUT-IN
LA36
00138

VENDOR
USED ON
CODE

CODe

REF
FIG
PART NO. NO.
2A

70-09779-01
70-09779-02

*Power Transformer (60 Hz)
*Power Transformer (SO Hz) Includes Capacitors

2
3
4
5
6
7
8
9
10
11

*Connector (P31, Pin Housing, 8 Pin Mate-N-Lok
*Terminal, Pin Contact
*Connector (J2) Pin Housing, 3 Pin Mate-N-Lok
*Connector (J1) Pin Housing, 4 Pin Mate-N-Lok
*Terminal, Pin Contact
*Terminal, Ring Tongue
*Cable Tie
*Tubing, Heat Shrinkable
*Tubing, Extruded
*Terminal, Quick Connect

JN K PS
MRLQ

16·12522-00
16-12521-00
12-09340-01
12-09378-00
12-10821-03
12-09351-04
12-09379-00
90-07928-00
90-07031-00
91-07253-09
91-07244-00
90-07970-00

8
10

LA36-06A

Figure BA. Transformer Assembly

31/32

IPB-LA36

FIG
&

ITEM
NO.

DESCRIPTION

DEC
PART NO.

D.C. MOTOR and ENCODE R ASSEMBLY

70-09691-00

1
2
3
4
5
6
7
8
9

-Motor, D.C.
-Encoder Base Harness Assembly
-Screw, Phi Pan Hd No. 4·40 x .75
-Clamp, Collar
-Pulley, Timing
-Screw, Soc Hd Cap No. 6-32 x .38
-Nut, Hex No. 6-32
-Disk Assembly
-Clamp, Cable

70-09 780-00
70-09177 -00
90-06015·01
74·11124-00
74-11035'()1
90-08045-08
90-08957-00
70-09178-00
9O'()7079-OO

10
11
12
13
14
15
16
17
18
19
20
21
22

-Screw, Phi Pan Hd No. 8·32 x .31
-Washer, Split Lock No.8
-Washer, Flat No.8
-Terminal, Strip Tie Down
-Capacitor (.01 MFD)
-Jumper
-Jumper
-Jumper
-Jumper
-Screw, Phi Pan Hd No. 6-32 x .18
-Washer, Ext Tooth No.6
-Decal, Ground
-Dust Cover, Encoder

90.()6036'()1
9O.Q609O-OO
90-06661-00
9O'()7004-OO
10'()1010.()1
70·10001-09
70·10001·10
70·1ooo1'()7
70·1ooo1'()5
9O·08020'()1
90·07649·00
36·12680-00
74·11416-00

ECO
CUT·IN
LA36
00166

VENDOR
USED ON
CODE

CODE

REF
FIG
PART NO. NO.
3

LA36·18

Figure 9. D. C. Motor and Encoder Assembly

33/34

IPB·LA36

FIG
&
ITEM
NO.
101
2
3
4
5
6

DEC
PART NO.

DESCRIPTION
CAPACITOR HARNESS ASSEMBLY

70-09895-00

-Connector. P2, Pin Housing. 8 Pin Mate-N-Lok
-Terminal, Pin Contact
-Connector, Solderless
-Connector. Solderless
-Tie Wrap
-Tie Wrap, Screw Down (de I et ed )

12-09340-01
12-09378-00
90-07928-00
90-07926-00
90-07031-00
90-07033-00

ECO
CUT-IN
70-09895

00000

VENDOR
USED ON
CODE

CODE

REF
FIG
PART NO. NO.
2.2A

LA36
00181

LA36·05

Figure 10. Capacitor Harness Assembly

35/36

IPB·LA36

FIG

&
ITEM
NO.
11-

1
2
3
4
5
6

DEC
PART NO.

70·10000

CABLE ASSEMBLY ILA36 Kevboard)ldeleted)

70·10000-00

LA36
00136

*Ceble, 24 Conductor INo. 22 AWG)
*Housing, Termination Berg
*Socket, Crimp
*Label, !THIS SIDE UP)
*Strain Relief
~Connector, Solderless Ideleted)
*Connector, Solderless ladded)

17·00011-01
12·10918·15
12·10089·07
36·11567 -00
12·11166-00
90·07917·00
90-07970-00

DESCRIPTION

*TieWrap

ECO
CUT·IN
00000

VENDOR
USED ON
CODE

CODE

REF
FIG
PART NO. NO.

A-H

LA36
00136

90·07031-00

2
3

LA36·16

Figure 11. Cable Assembly (LA36 Keyboard)

37/38

IPB·LA36

FIG
&
ITEM
NO.

DEC
PART NO.

DESCRIPTION

11A-

CABLE ASSEMBLY (LA36 Keyboard)

70-11519-00

1
2
3
4
5
6

*Ceble, 24 Conductor (No. 22 AWG)
·Connector, Housing 44 Pin Berg
*Terminels, Socket Crimp
*Strain Relief
·Label (THIS SIDE UP)
*Tie Wraps

17 -00011-01.
12-10918-15
12-10089-07
12-11166-00
36-11567-00
90-07031-00

ECO
CUT-IN
LA36
00136

VENDOR
USED ON
CODE
J-R,S

CODE

REF
FIG
P.ART NO. NO.
12A
13A

IL
::;)

III
C

iii

'"%
~

'2
3
4

LA36·16A

Figure 11A. Cable Assembly (LA36 Keyboard)

39/40

IPB·LA36

FIG

&
ITEM
NO.
12-

1
2
3
4
5
6
7
8

ECO
CUT-IN

VENDOR

DESCRIPTION

DEC
PART NO.

70-09750
00001

USED ON
CODE

KEVBOARD BEZEL ASSEMBL V (deleted)

70-097~1

LA36
-00163

EFGH

• Bracket , Bezel
·Spacer, Hex No.8 x 1.00
·Spacer, Hex No.8 x .75
·LK02 KEVBOARD ASSEMBL V
·Nut, Kep No. 8-32
·Switch, Rocker (DPSTI
·Switch, Rocker (3 Position)
·Washer, Split Lock No.6
·Screw, Phi Pan Hd No. 6-32 x .31

74-11427-01
90-09285-00
90-07868-00
LK02-OO
90-06563-00
12·11621-00
12·11732-00
90-07801-00
90-06021-01

CODE

REF
FIG
PART NO. NO.
1

EFGH

EFGH (See IPB Manual EK-LK02-IP-)

I
\
I

r
I

LA36·14

Figure 12. Keyboard Bezel Assembly

41/42

IPB·LA36

~DmDDmD\
LlS~/
PARTS

I
I

¢-J

LA36-14A

Figure 12A . Ke y b oard Bezel Assembly

IPB-LA36

FIG

&
ITEM
NO.
12A1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16

17
18
19
20
21

DESCRIPTION

DEC
PART NO.

KEYBOARD BEZEL ASSEMB L Y
KEYBOARD BEZEL ASSEMBLY (added)
·Bracket, Bezel
·Bracket, Bezel (added)
·Spacer, Hex No.8 x 1.00
·Spacer, Hex No.8 x .75
·Nut, Kep No. 8-32
·LK02 KEYBOARD ASSEMBLY
·Control Panel Cable
·FRONT CONTROL PANEL ASSEMBLY
··Keycap Set
"Front Control Panel Assembly
·Switch, Rocker (DPST)
·Grommet
·Screw, Phi Pan Hd No. 6-32 x .31 (deleted)
·Washer, Split Lock No. 6-32 (deleted)
• Harness Clip
·Jumper
·Washer, External Tooth No.8
-Decal, Ground Symbol
·Washer, Flat Nylon No.8
·KEYBOARD CABLE ASSEMBLY
• Spacer , No.8 x .375 (added)
-Jumper, Interlock (added)

70-09750-01
70-09750-03
74-11427-01
74-11427-03
90-09235-00
90-07868-00
90-06563-00
LK02-OO
70-08612-0K
70-1 1525-00
12-12287 -E3
54-11727-00
12-11621-00
90-09713-01
90-06021-01
90-07801-00
90-08340-00
70-10001-05
90-08072-00
36-12680-00
90-06708-00
70-11519-00
90-06802-00
70-10001-13

ECO
CUT-IN
LA36
00163

00247
00247

VENDOR
USED ON
CODE

CODE

REF
FIG
PART NO. NO.

NPQR
S
NPOR
S

1A
1A

J-R,S
J-R,S
J-R,S

(See IPB Manual EK-LK02-IP-)

00205
00205

See Note
00205
00219

11A

Note: This Assembly formerly installed under
Figure 1A. (Per ECO LA36-OO219)

IPB·LA36

FIG

&
ITEM
NO.

DEC
PART NO.

70-09750
00001

USED ON
CODE

DESCRIPTION

ECO
CUT·IN

VENDOR

REF
FIG
PART NO. NO.

CODE

13-

KEYBOARD BEZEL ASSEMBLY (deleted)
(With Cursor Control)

70-09750-02

LA36
-00163

ABCD

·LK03 KEYBOARD ASSEMBLY (deleted)

LK03·oo

LA36
-00136

ABCD (See IPB Manual EK·LK03·IP· )

2
3
4
5
6
7
8
9
10
11

·LK02 KEYBOARD ASSEMBLY
·Cable, Keyboard
··Cable, 16 Conductor
··Connector, Dual In Line 16 Pin
·Bracket, Bezel
·Spacer, Hex No.8 x 1.00
·Spacer, Hex No.8 x .75
·Nut, Kep No. 8-32
·Switch, Rocker (DPST)
·Switch, Rocker (3 Position) (deleted)

LK02·oo
70·08612-oD
91-07738-00
12·10722-00
74-11427-02
90-09825-00
90-07868-00
90-06563-00
12-11621-00
12-11732-00

12
13

·Washer, Split Lock No.6
·Screw, Phi Pan Hd No. 6-32 x .31

90-07801-00
90-06021-00

A-H

(See IPB Manual EK·LK02·IP· )

ABCD

LA36
-00136

I
10-

/11

12~

13--J

I
I

9
LA36·15

Figure 13. Kevboard Bezel Assemblv (W/Cursor Control)

45/46

IPB·LA36

~DmDamD\
LlS~
PARTS

)

\~17

~6
2

LA36-15A

Figure 13A. Keyboard Bezel Assembly (w/curso r Contra/)

IPS-LA36

47
4

FIG
&
ITEM
NO.

DESCRIPTION

DEC
PART NO.

13A-

KEYBOARD BEZEL ASSEMBLY
(With Cursor Controll

70-09750-02

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23

*Bracket, Bezel
*LK02 KEYBOARD ASSEMBLY
* LK03A KEYBOARD ASSEMB L Y
*Spacer, Hex No.8 x 1.00
*Spacer, Hex No.8 x .75
*Nut, Kep No. 8-32
*Cable (Keyboard to Cursorl
*Cable (Control Panel to Keyboard)
*FRONT CONTROL PANEL ASSEMBLY
* * Keycap Set
**Front Control Panel Assembly
*Grommet
*Switch, Rocker (DPST)
*Screw, Phi Pan Hd No. 6-32 x .31 (deleted)
*Washer, Split Lock No.6 (deleted)
* Harness Clip
*Jumper
*Washer, External Tooth No.8
*Decal, Ground Symbol
*Washer, Flat Nylon No.8
-KEYBOARD CABLE ASSEMBLY
*Spacer, No.8 x .375 (added)
-Jumper, Interlock (added)

74-11427-02
LK02-00
LK03A-00
90-09285-00
90-07868-00
90-06563-00
70-08612-00
70-08612-OK
70-11525-00
12-12287-00
70-11727-00
90-09713-01
12-11621-00
90-06021-01
90-07801-00
90-08340-00
70-10001-05
90-08072-00
36-12680-00
90-06708-00
70-11519-00
90-06802-00
70-10001-13

ECO
CUT-IN

LA36
00163

VENDOR
USED ON
CODE
JKLM

J-R,
JKLM

CODE

REF
FIG
PART NO. NO_
1A

(See IPB Manual EK-LK02-IP-)
(See IPB Manual EK-LK03A-IP-)

00205
00205

See Note
00205
00219

11A

Note: This Assembly formerly installed under
Figure 1A. (Per ECO LA36-00219)

IPB-LA36

FIG
&
ITEM
NO.
14-

1
2
3

ECO
CUT·IN

VENDOR

DEC
PART NO.

BC05·F
00001

USED ON
CODE

CABLE ASSEMBLY (BC05F Interfece) (deleted)

BC05F·15

LA36
-00165

ABEF

*Cable,4 Conductor (No. 22 AWGI
*Connector (P1, P2) Pin Housing, Mate·N·Lok
*Terminal, Pin Contact

91·07706-00
12-09340-01
12-09378-03

DESCRIPTION

CODE

REF
FIG
PART NO. NO.
1

DEC

r----~--'""'--""li~

LA36-17

Figure 14_ Cable Assembly (BC05F Interface)

49/50

IPB-LA36

APPENDIX C
REFERENCE DATA
C.I ABBREVIATIONS
The abbreviations used in this manual are listed in Table C-l.
C.2 SIGNAL GLOSSARY
The signal names used in this manual are listed in Table C-2.
C.3 IC PIN LOCATION DRAWINGS
The pin locations of the integrated circuits used in the LA36 are shown at the end of this appendix.

C-l

Table C-l

Glossary of Abbreviations

2SB

Two Stop Bits

AKa
AMP
AR

Any Key On
Amplifier
Address Register

BCD
BEL
BS
BUF
BUFF

Binary Coded Decimal
Bell
Backspace
Buffer
Buffer

C/B
CBRAM
CBA
CGROM
CHAR
ClK
ClR
CM
CNTR
Cal
COlHI
Calla
CONTROL RAM
CRAM
CTRl

Carry/Borrow
Character Buffer Read Access Memory
Character Buffer Address
Character Generator Read Only Memory
Character
Clock
Clear
Centimeter
Counter
Column
Column High
Column low
Control Read Access Memory
Control Read Access Memory
Control

D/A
DAC
DEC
DM
DRVR

Digital to Analog
Digital to Analog
Decoder
Direction
Down
Driver

ENB
ER

Enable
Error

F/F
FIFO

Flip Flop
First In/First Out

H
HDE

High
Head Drive Enable

INC
INIT
IPS

Increment
Initialize
Inches Per Second

DIR

C-2

Table C-l

Glossary of Abbreviations (Cont)

KBD
KBH
kHz

Keyboard
Keyboard Hold
Kilohertz

Low
Last Character Visibility
Line Feed
Least Significant Bit

LCV
LF
LSB

MHz
mm
MPC
ps
ms
MSB
MUX

Meter
Megahertz
Millimeter
Microprogrammed Controller
Microseconds
Milliseconds
Most Significant Bit
Multiplexer

NB
ns

Number Of Bits
Nanoseconds

pas HI
pas La
POSIT
PT

Position High
Position Low
Position Middle
Position
Position
PRINT Timer

R
RAM
RCV
RCVR
RDADR
RD
RD
REG
ROM

Read or Register
Read Access Memory
Receive
Receiver
Read Address
Read or Register
Receive Data
Register
Read Only Memory

ST
SYNC

Status
Synchronize

TACH
TTL

Tachometer
Transitor To Transistor Logic

UART

Universal Asynchronous Receiver Transmitter

VREF

Voltage Reference

POSMD

pas

C-3

Table C-l

Glossary of Abbreviations (Cont)

WC
WDCNT
WTADR

Word Count
Word Count
Write Address

Read Access Memory Transmit Data
Transmit

XMIT

C-4

Table C-2
Mnemonic

Signal Glossary

Definition

Source

Destination

BELL SINK

Bell Return

J5-2

Speaker

BELL SOURCE

+5 V to Bell

R118

J5-1, Speaker

COMMON

From LF Motor

J54

LF Motor

PHASE 1

To LF Motor

J5-7

LF Motor

PHASE 2

To LF Motor

J5-6

LF Motor

SOL 1:7

Solenoid Driver Outputs to Head
Solenoids

MPC3 BMBOO

Buffered Memory Bit 0

ES84 or E614

E49-9, E21-2
E31-15, E15-15

MPC3 BMBOI

Buffered Memory Bit 1

E58-5 or E61-S

E49-5, E21-S
E3 1-14, E 15 -14

MPC3 BMB02

Buffered Memory Bit 2

E58-6 or E61-6

E49-3, E21-8
E31-13, ElS-13

MPC3 BMB03

Buffered Memory Bit 3

ES8-7 or E61-7

E49-1,E21-11
E31-1 1 , E 15 -II

MPC3 BMB04

Buffered Memory Bit 4

E58-8 or E61-8

E54-13, E46-23
ESO-IS

MPC3 BMBOS

Buffered Memory Bit 5

ES8-9 or E61-9

ES4-11, E46-22
ESO-14

MPC3 BMB66

Buffered Memory Bit 6

E58-10 or
E61-10

ES4-9, E53-1
E46-21, ESO-13

MPC3 BMB07

Buffered Memory Bit 7

ES8-11 or
E61-11

ES4-S, E53-2
E46-20

MPC3 MBOO

Memory Bit 00

ES84 or E614

MPC3 MBOl

Memory Bit 01

E58-5 or E~I-S

MPC3 MB02

Memory Bit 02

ES8-6 or E61-6

MPC3 MB03

Memory Bit 03

E58-7 or E61-7

MPC3 MB04

Memory Bit 04

E58-8 or E61-8

MPC3 MB05

Memory Bit 05

ES8-9 or E61-9

C-5

Table C-2
Mnemonic

Signal Glossary (Cont)

Definition

Source

Destination

MPC3 MB06

Memory Bit 06

ES8-10 or
E61-1O

MPC3 MB07

Memory Bit 07

ES8-11 or
E61-11

MPC4 CLR BEL

Clear Bell

E44-9

E36-3

MPC4 CLRC/B

Clear Carries or Borrows

E44-16

EII-13

MPC4CLRDA

Clear Data Available

E44-2

E60-11

MPC4CLRHDE

Clear Head Drive Enable

E44-13

E39-11, E30-11

MPC4 CLR INIT

Clear Initialize

E44-17

ESI-I

MPC4CLRKBH

Clear Keyboard Hold

E44-1

ESI-IO

MPC4 CLR S68

Clear S68

E44-6

EIS-23, E31-4
E30-4

MPC4 CSOO

Clocked Selector 04

E46-1

E42-1

MPC4 CSOl

Clocked Selector 04

E46-2

E42-2

MPC4 CS02

Clocked Selector 04

E46-3

E42-13

MPC4 CS03

Clocked Selector 04

E46-4

E37-4

MPC4 CS04

Clocked Selector 04

E46-S

E37-S

MPC4 CS10

Clocked Selector 04

E46-9

MPC4 CS11

Clocked Selector 04

E46-10

E27-3

MPC4 CS12

Clocked Selector 04

E46-11

E44-18,19

MPC4 CSl3

Clocked Selector 04

E46-13

E44-18,19

MPC4 CSl4

Clocked Selector 04

E46-14

E42-S

MPC4 CSIS

Clocked Selector 04

E46-IS

E37-1, E42-3

MPC4 CS16

Clocked Selector 04

E46-16

E37-2, E37-I3
E42-4

MPC4 CSl7

Clocked Selector 04

E46-17

ES3-4

C-6

Table C-2

Signal Glossary (Cont)

Mnemonic

Definition

MPC4 LOAD CBA

Load Character Buffer Address

E44-4

E52-9

MPC4 LOAD D/ A

Load Digital/Analog

E44-10

E14-9

MPC4MAX

Maximum

E23-6

E31-5, E14-4, 5,
12, 13

MPC4 REGO:3

E32-2, 3, 6, 7

E52-4, 5,12,13
E38-1,5,9,1O

MPC4 soon

Selector 0

E50-1

E22-2

MPC4 SOOI

Selector 1

E50-2

E27-2

MPC4 S002

Selector 2

E50-3

E21-3

MPC4 S003

Selector 3

E50-4

E31-9

MPC4 S004

Selector 4

E50-5

E15-9

MPC4 SET BEL

Set Bell

E44-9

E36-4

MPC4 SET HDE

Set Head Drive Enable

E44-11

E39-1O

MPC4 SET HOLD

Set Hold

E44-15

E40-4

MPC4 STEP LF

Step Line Feed

E44-14

E24-3, 11, E29-5

MPC4 SKIP

Skip

E40-11

E60-2

MPC4 WRITE BUF

Write Buffer

E44-5

E60-10, E56-3

MPC4 ZERO

Zero

E23-8

E18-13, E31-3, 6

MPC4 -1 REG

Decrement Register

E44-7

E32-4

MPC4 +1 REG

Increment Register

E44-3

E32-5

MPC5 CLK

Clock

E64-5,12

E46-18, 19,
E29-1O, E49-13

MPCS S.1.

Serial In

E66-6

ES5-20

MPC5 1.1841-1s

1.1841-1s

E13-I2

E37-1O, EI3-1,
E64-9, E7-13,
E9-3, 11

MPCS 1.76 kHz

1.76 kHz

E68-11

E30-3, ES9-3

Source

C-7

Destination

Table C-2
Mnemonic

Signal Glossary (Cont)

Definition

Source

Destination

MPC5 4.8 kHz

4.8 kHz

E63-11

E26-14, E17-4

MPC519

E26-9

E67-5, E31-21, 22

MPC5 76 J.l.S

76 pS

E26-11

E3-3, E5-3

MPC5208

208

E26-12

E40-10, E67-11,
EI7-7, EI5-7,
E3I-I9

MPC5568

568

E30-5,6

E64-IO, E9-4, 10
EI3-14, E37-9

MPC5 592 ns

592 ns

EI7-I3

E20-J

MPC6 BEL

Bell

EI9-I

E 15-(,

MPC6 BS

Back Space

EI9-9

EI5-20

MPC6 CR

Carriage Return

EI9-3

E25-13, EI5-4

MPC6 DA

Data Available

E55-19

E3I-7

MPC6 HSI:7

Head Select

E28-4 to 11 and
E33-4 to 11

Head Solenoid
Drivers

MPC6 HT

Horizontal Tab

EI9-7

E15-21

MPC6 KBH

Keyboard Hold

E5I-8

E3I-20

MPC6 LF

Line Feed

EI9-6

E25-1,EI5-5

MPC6 PNTABL

Printable

E33-I1

E25-11,E3I-l

MPC6 S.O.

Serial Out

E55-25

E29-I2

MPC7 BORROW

Borrow

EI2-3

EI2-I, E15-22
E3I-18

MPC7 CARRY

Carry

E7-6

E31-23

MPC7 COL INC
COUNT 0:2

Column Increment Count

EI6-2, 3, 6

E28-19 to 21,
E33-I9 to 21

MPC7 INC

Increment

E30-9

E15-3

MPC7 PT COM +5 V

Print Timer Common

11-U,V

11-13,17
(RI, R2)

C-8

Table C-l

Signal Glossary (Cont)
Source

Definition

Mnemonic

Destination

MPC7SUM

Sum

EI-6 (11-B)

MPC8 BEL

Bell

R58

11-TT,11-38

MPC8 HDE (HDEM)

Head Drive Enable

E39-8

J5-2

MPC8INIT

Initialize

E5 1-5,6

EII-2, E31-8

MPC8 LFI

Line Feed 1

E24-9

11-JJ

MPC8 LF2

Line Feed 2

E24-5

11-P

MPC8 LF HOLD

Line Feed Hold

E29-6

11-HH

MPC8 W.U.

Wake Up

Q9-C

E53-5, ElO-12,
E36-1, J I-DO,
E14-1

P.T. COLL 1

Print Timer Collector 1

QI-C (11-21)

11-Y (E34-2)

P.T.COLL 2

Print Timer Collector 2

Q2-C (J1-25)

JI-CC (E35-2)

C-9

380 QUAD 2-INPUT NOR GATE

Vee

GND

IC-OO' 3

1702A

8-BIT REPROGRAM MABLE ROM

PIN CONFIGURATION
24

VDD

Vee

*DATA OUT I

4(LSB)

*DATA OUT 2

*DATA OUT 3

*DATA OUT 4

*DATA OUT 5

*DATA OUT 6

VGG

*DATA OUT 7

V8B

*DATA OUT 8

11(M.B) 14

Vee

PROGRAM

*THIS PIN IS THE DATA INPUT DURING PROGRAMMING

C-lO

2627P A6-01 CHARACTER GENERATOR ALPHA

PACKAGE "A" -

BENT LEADS

INDEX MARK
OR
---';---~
NOTCH
V GG • 1
---.

eS2
eS a

IC-0123

PACKAGE "B" - BRAZED LEADS

Vss
CS 1

eso

°0

AO
Al

°2

°1

°a

°4

°5

°7V DD

AS
IC-0120

IC-0124

C-ll

1627P A6-01 CHARACTER GENERATOR ALPHA (Cont)

FUNCTIONAL BLOCK DIAGRAM
11 10 9

CHIP SELECT
3

~I_ _

o 7 0 6 0 5 0 4 03 02 01 0 0

....A

TRI-STATE
OUTPUT STAGES

23
512 X 8 ROM
22

NOTE: Choice of connection A or B for each chip select
is available as a mask option.

13 14 15 16 17 18 19 20 21

IC-0121

C-12

3101

RANDOM ACCESS MEMORY

Easy memory expansion is provided by an active ,LOW chip select (ENB) input and open collector OR
tieable outputs.
An active LOW Write line WR controls the writing/reading operation of the memory. When the chipselect and write lines are LOW the information on the four data inputs Do to Do is written into the
addressed memory word.
Reading is performed with the chip select line LOW and the write line HIGH. The information stored
in the addressed word is read out on the four inverting outputs MO to M3.
During the writing operation or when the chip select line is HIGH the four outputs of the memory go
to an inactive high impedance state.

10
16 X 4

NON-OVERLAPPING

MATRIX

OF STORAGE CELLS

ROM DECODER

VCC =PI N 16
GND = PIN 08

=Df-----l--/
-L-!
--LWR

ENS

{>-

FFFJ
M0

M3
IC- 3101

C-13

7400 QUAD 2-INPUT POSITIVE NAND GATE

7400
03
01~

04=Y05
7400
06

04~
7400
06

01~
7400
03

09~
09~
740
08
7400
08
10

12~
13
7400
11

12~
13
740
11

vee =PIN 14
GNO· PIN f117

7401

IC-7400

NAND GATE-QUAD 2-PIN OPEN COLLECTOR

Vee.

4 '(

II-A

3'(

3.8

,8 GND
IC-0129

C-14

7404 HEX INVERTER

GND

POSITIVE LOGIC: Y· A
IC-0011

7408 QUAD 2-INPUT POSITIVE AND GATE

GND

POSITIVE LOGIC: Y· AB
ZC-OO'4

C-15

7410 TRIPLE 3-INPUT POSITIVE NAND GATE

03~
04
7410
06 03~
04
7410
06
05

09~
09~
10
7410
08 10
7410
08
11

13~13~
7410
12 01
7410
12

01
02

vee =PIN 14
GND =PIN 1/)7

Ie -7410

7413 SCHMITT TRIGGER

BINARY SELECT

GNO

POSITIVE LOGIC: y. ABCO

,
IC-0008

OUTPUTS

IC-0009

C-16

7416

HEX INVERTER BUFFER/DRIVER

GND

POSITIVE LOGIC, Y' As

7417

HEX BUFFERS/DRIVERS

Vee

GND

POSITIVE

LOGIC Y'A
IC-OOS7

.--___--+__
4Kn

3Kn

>----~vcc

2Kn

OUTPUT Y

INPUT A

2KSl
L----------~~~~-~-~GND

Componenl volues shown ore nominal
le-OOS6

C-17

7420 NAND GATE-DUAL 4-INPUT

(iNl>
IC-0128
IC-0130

7437

NAND GATE-QUAD 2 IN BUFFER, 14 PIN

GND

IC-0126

C-18

7442 4-LINE-TO-IO-LINE DECODERS
These BCD-to-decimal decoders consist of eight .inverters and ten 4-input NAND gates. The inverters
are connected in pairs to make BCD input data available for decoding by the NAND gates.

f9
fa
f7
12

f6
7442

13
aCD
INPUT

DECIMAL
OUTPUT

f4
f3

f2
f 1

VCC = PIN 16
GND= PIN oa
IC-7442

7442
TRUTH TABLE

BCD
Input
02
01

0
0

0
1

0
1
1
1
1

1
1

0
0

1
1

0
0
0
0

0
0

1
1

1
1
1
1

0
0

1
1

0
0
0
0
1
1
1
1
1
1
1
1

1
1
1
1
1
1

10
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1

11
1

0
1
1
1
1
1
1
1
1
1
1
1
1
1
1

12
1
1

0
1
1
1
1
1
1
1
1
1
1
1
1
1

f3
1
1
1
0
1
1
1
1
1
1
1
1
1
1
1
1

C-19

Decimal
Output
15
14
1
1
1
1
1
1
1
1
0
1
1
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1

16
1
1
1
1
1
1

0
1
1
1
1
1
1
1
1
1

17
1
1
1
1
1
1
1

0
1
1
1
1
1
1
1
1

18
1
1
1
1
1
1
1
1

0
1
1
1
1
1
1
1

19
1
1
1
1
1
1
1
1
1

0
1
1
1
1
1
1

7474

DUAL D-TYPE EDGE-TRIGGERED FLIP-FLOP

TRUTH TABLE FOR
7474 STANDARD CONFIGURATION
(EACH FLIP·FLOP)
tn+ 1

Preset
Pin 4(10)
High
High
High
Low
Low

o Input
Pin 2(12)
Low
High

Clear
Pin 1(13)
High
High
Low
High
Low

X
X
X

o Side
Pin 6
High
Low
High
Low
High

1 Side
Pin 5
Low
High
Low
High
High

tn = bit time before clock pulse.
tn+ 1 = bit time after clock pulse.
X = irrelevant

STANDARD CONFIGURATION

REDIFINED CONFIGURATION

PRESET

PRESET
02

03 C

04
CLEAR

CLEAR
PRESET
10

"
CLEAR
VCC' PIN 14
GND'PIN07

IC-7474

C-20

7489

64-BIT READ/WRITE MEMORY

WRITE
ENABLE

MEMORY
ENABLE

ENB

OA"{

INPUTS

1",,,

7489

OUTPUTS

SELECT( INPUTS)
MEMORY ADDRESS
VCC'PIN 16
GND·PI N 08
IC-7489

ENB
L
L
H
H

7493A

WR
L
H
L
H

CONDITION OF OUTPUTS

OPERATION
Write (WR)
Read (ENB)

Complement of Write Data Inputs into addressed memory location.
Reads complement of word stored in selected memory location.

Inhibit Storage

Complement of Data Inputs

Do Nothing

High

COUNTER ASYNCHRONOUS UP, BINARY

4
5
PIN LOCATOR
(TOP VIEW OF IC)
3

C-21

74123

MONOSTABLE MULTIVIBRATOR

The 74123 Monostable Multivibrator provides dc triggering from gated low-level active (A) and highlevel active (B) inputs. Overriding direct clear inputs and complementary outputs are also provided.
By triggering the input before the output pulse is terminated, the output pulse may be extended. The
overriding clear capability permits any output pulse to be terminated at a predetermined time, independently of the external timing components.

15
,,--..., 13

A2
B2

o 12

"
+5V=PIN 16
GND = PIN 8
IC-74123A

TRUTH TABLE
INPUTS

OUTPUTS

Jl..
Jl..

-u-u-

NOTE' H= high level (steady slate), L= low level (steady slale),
,= transition from low 10 high level, 1= transition from
high to low level,
= one high-level pulse, -U- = one

.:.n...

low-level pulse, X= irrelevant (any Input, including transitions)
IC-741238

C-22

74150

DATA SELECTOR/MULTIPLEXER
• LOW TO ENABLE
• OUTPUT IS HIGH
IF STROBE IS HIGH

STROBE
(ENABLE)
9
STB
16

17
18
19
20
21
22
23

DATA
INPUTS
BCD

1
2
3
4
5
6
7
8

015
014
013
012
011
010
09
10

74150

OUTPUT

07
06
05
04
03
02
01

+5V = PIN 14
GNO=PIN7

74150 TRUTH TA8LE
INPUTS
S3

52 SI

0
0
0
0
0
0
0
0
0
0

0
0
0
0
0
0
0
0
1
1

0
0
0
0
1
1
1
1
0
0

0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1

1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1

0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1

0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1

STROBE
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

OUTPUT

00 01

02 03 04 05 06 07 08 09 010 011 012 013 014 015

X
X
X
X
X

0
1

X
X
X

0
1

X
X
X
X

X
X
X
X
X
X
X
X
X

X
X

0
1

X
X

X
X
X
X

X
X
X
X
X
X
X

0
1

X
X
X
X
X

X
X
X
X
X
X
X
X
X
X

X
X
X
X
X
X
X
X
X
X
X
X

X
X

X
X
X
X
X

0
0

X
X

X
X
X
X

0
1

X
X
X
X
X
X
X

X
X

X
X
X

X
X
X
X
X
X
X
X
X
X
X
X

X
X
X
X
X

X
X
X
X
X
X
X

X
X
X
X
X
X
X
X
X
X
X

X
X
X
X
X
X
X

0
1

X
X
X
X
X

0
1

X
X
X

X
X
X
X

X
X

0
1

X
X

X
X
X
X
X
X
X
X
X
X

X
X
X
X
X
X
X
X
X
X
X

0
1

X
X
X
X
X

X
X
X
X
X
X
X
X
X
X

X
X
X
X

X
X
X
X
X
X
X

X
X
X
X
X
X
X
X
X
X
X

X
X

X
X
X
X
X

X
X
X
X

X
X
X
)(

X
X
X
X

X
X
X

X
X
X
X

X
X
X

X
X

X
X
X
X
X
X

0
1
X
X
X
X

0
1

X
X
X
X
X
X
X

X
X

0
1

X
X
X

X
X
X
X
X
X

0
1

X
X

X
X
X

X
X
X
X
X

X
X
X

X
X
X
X
X
X
X

f
1
1
0
1
0
1
0
1
0
1
0

X
X
X

X
X
X
X
X
X
X
X
X
X
X

X
X
X
X
X
X
X
X
X
X
X
X

0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0

X
X
X
X

X
X
X
X
X
X
X
X
X

X
X
X
X
X
X
X
X
X
X

0
1

X
X

X
X
X
X

0
1

X
X
X
X

X
X

0
1

X
X
X

When used to indicate an input condition, X = LOGICAL 1 OR LOGICAL 0
IC-74150

C-23

74154 4-LINE-TO-26-LINE DECODER/DEMULTIPLEXER
The 74154 4-Line to 16-Line Decoder decodes four binary-coded inputs into one of 16 mutuallyexclusive outputs when both strobe inputs (G I and G 2) are low. The decoding function is performed
by using the four input lines to address the output line, passing data from one of the strobe mputs with
the other strobe input low. When either strobe input is high, all outputs are high.

17
f 15
f'4
f13
f 12
fll
flO
fg
f8
74154

f7
f6

16 OUTPUTS
1 OF 16 MUTUALLY
EXCLUSIVE OUTPUTS
DECODED FROM BCD INPUT
WHEN BOTH STBI AND
STBO ARE LOW

IN~~~ {

FOR DECODING

03
02
01
DO

STBI

STBO
18

+5V'PIN 24
GND'PIN 12

Notes For Demultiplexing:
Inputs used to address output line.
Data passed from one strobe input
with other strobe held low. Either
strobe high gives all high outputs.
Ie -74154

C-24

74161

4-BIT BINARY COUNTER
3

RO(I)

Rt( I)

R2(1)

R3(1 )

OATA{
INPUTS

5
6

"}
12

OUTPUTS

74161
CLEAR
lOAD ----<lIlD
ClK

CLOCK
ENABLE P
ENABlET

CNT EN
CO 15

CRY EN

CARRY
OUTPUT

GND' PI N 8
+5V' PIN 16

typical clear,preset, count, and inhibit sequences for 74161
Illustrated below is the following sequence:
1. Clear outputs to zero
2. Preset to BCD seven
3. Count to eight, rune, lero, one, two, and three.
4. Inhibit

CLEAR
PINOI

LOA()

DATA
INPUTS

IASYNCHRONOUSI

DO
PIN03

Dt
PIN04

D2
PIN05

L=
L=
[

D3
PIN06
CLOCK
PIN02
[NABLE P

PIN07
I

ENA8LE 1

PINtO
ROlt I
PIN t4

OUTPUTS
R21tl PIN'2 _
R3(1) PIN 11

CARRY
PINt5

,1-_ _ _ _ _ _ _ _ _...1

Rt I I I
PINt3 _

=LJI
=LJI

,~----------------------------

-l

o'r- - - - - - ,

______~,__r-~~r-lL--------~-------------r

: 7

I-----COUNT-----~·I....
• -----INH'BIT----_

CLEAR PRESET

IC-14161

C-25

7417~

QUAD D-TYPE FLIP-FLOP WITH CLEAR

TRUTH TABLE
INPUT
tn

OUTPUTS
tn"

R(1 )R(O)

H
L

(4)

RO (2)
(1 )

RO (3)
CLK (0)
CLEAR

L
H

tn =Bit time before
cloc k pulse.
tn"= Bit time after
clock pulse.

Dl (5)

(7)

(1 )

Rl (6)
CLK (0)
CLEAR

R3(1 )
R3(0)

12
DATA
INPUTS

R2( 1)
R2(0)

R 1( 1)
R 1(0)

RO(l )
RO(O)

R2 (10)
(1 )

11
7

OUTPUTS
R3

03 (13)
D3

6
CLOCK

R2 (11)
CLK (0)
CLEAR

74175
5

020:(-,12:':')+--+_4

-+---a CLK (0)
R 3 (14)

L . - _ -....

(15)

(1)

CLEAR
3
CLEAR
Pin (16)= VCC. Pin (8)=GNo

9
Ie -74175

C-26

74190 COUNTER, SYNCHRONOUS UP/DOWN DECADE, 16 PIN

DATA
INPUTS

{..

MSB

06
02

lSB

--------~

74190

PRESET

'"'"""J

REG (NUMBER)

OUTPUTS
"EO
REG (NUMBER)
REG (NUMBER)

ReQister number is
unique to product
line

CRY 12
STATE

CNT ClK

RIPPLE
CLOCK
Vee=PIN 16
GND=PIN 08

Iypicol lood, counl, and inhibit sequences for 74190
Illustrated below IS the following sequence:
1 Load (preset! to BCD seven.
2. Count up to eight, nine (maximum), zero, one, and two.
3. Inhibit.
4. Count down to one, zero (minimum), nine, eight, and seven.

PIN" PRESET

~
I

rTI'1
i IL

PIN 15

--.J

Ii"""--n
.-.J i
i L...

PIN 01
DATA

I N PUTS

~L
I
I

PIN 10

,
PINQ9

COUNT
DOWN

PINOS

ENABLE
PI N04

I r

~7--7----------------------~

E~~~~~ 11...-+__-'--'________________---'

PIN03

PIN02

PIN06

===~I""il!-:

----ri

---~
PINQ?

____----'1,

I
I

I ~;----------------~--------~~~--------------~.

==~~
I,
'-++----J
~ ~

PIN12 CARRY---,
STATE ____

----I

PIN 13 RIPPLE
CLOCK ___ ....J

I I
I I

I I

'--___..;-______....;-__..;-__...J!

.......,

U
8

r
0

II...._ _ _ _ _ _ _ _ _ __

I 2

I II---COUNTUP-J--INHIBIT--I f...--

COUNT DOWN - - - - -

~
LOAD

Ie -74190

C-27

74193

SYNCHRONOUS 4-BIT UP/DOWN COUNTER

The 74193 Binary Counter has a individual asynchronous preset to each flip-flop, a fully independent clear
input, internal cascading circuitry, and provides synchronous counting operations.

typical clear,load,and count sequences for 74193

Illustrated below IS the follOWing sequence

1. Clear outputs to zero
2. Load (preset) to BCD thirteen
3. Count up to fourteen. fifteen, carry, zero, one, and two
4 Count down to one, zero, borrow, fifteen, fourteen. and thirteen

SEE
NOTE

PIN 14

ClfAR

PIN 11

DATA
INPUTS

R3(11

74193

R211)

=]
02

RUI}

RO{1 )

DATA

OUTPUTS

PIN 01

['""

giN 10

lPIN09

:I',: : : : :
PIN 05 ((I

~------'I-

-.J

L _______ _

'\,'

Clear overrides load, data, and count mputs

2. When countmg up, count down Input must be high,
when counting down, count·up Input must be high.
3 Produce pulses equal to Width of count pulses
during: Underflow (BOF1:ROW)
Overflow (CARRY)
4. ClR Input high forces all Outpu15 low. ClR
overndes load, data and ON/UP Inputs
5 Preset to any state by applYing Input data With
load Input low. Output changes to agree With Inputs
Independent of count pulses.
6 Select ON or UP clock while other IS held high

0119

PIN06 R2 " I

PIN 07 R3 (I)

, I

OUTPUTS

NOTES'

-- -- --

L================

..J
-.J

PI~G4 L~:(\U.~~:

14
SEE SE E '------'
NOTE NOTE SEE
4
5
NOTE

I
I 1
I 1
- - -- -- -- -- -- - - - - - - - - I
I~ _ _ _ _ _ - - - - - - - - - - I I
I 1
r1 I
-----~,
-- -- --1 I
1 I
1 I
I I
r-~~-~'I
__ __ __ __ __ __ __ __ __
I I
1

CRY BRW

---.flI
1

LJl...JLJLSl.J I

~'_'~__~______- .

=~
1

L -_ _ _ _ _ _ _--'

. -_ _ _ _-:--_

=~I
I I
I I
I

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Reader's Comments

LA36 DEC writer II
Maintenance Manual
Volume I
EK-ILA36-MM-OOI

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