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Document:	LA36 DECwriter II Maintenance Manual Volume 1
Order Number:	EK-1LA36-MM
Revision:	1
Pages:	406
Original Filename:

OCR Text

Thic

Ay RSN

030020

EK-1LA36-MM-001

LA36 DECwriter |l

MAINTENANCE MANUAL
Volume |

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

DECtape

DECCOMM

DECUS

PDP

RSTS

DECsystem-10

DIGITAL

TYPESET-8

DECSYSTEM-20

MASSBUS

TYPESET-11
UNIBUS

9/77-14

CONTENTS

CHAPTER 1

GENERAL DESCRIPTION

1.1

PHYSICAL CHARACTERISTICS

1.2

FUNCTIONAL DESCRIPTION

1.2.1

Character Printing

1.2.2

Bell Operation

. . . . . . . . . . . . . . . . e

1.2.3

Paper Feeding

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

1.2.4

Ribbon Drive System

. . . . . . . . . . . .. . . . . ...,

1.2.5

Carriage Servo System

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

1.2.6

Power Supply

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

i e

. . . . . . . . . . . . . . .. ...
e

e e

. . . . . . . .

e
e

1.2.7

Standard Current Loop Interface

1.2.8

Optional Half-Duplex (Active or Passive) Current Loop Interface

1.2.9

Peripheral Interface Port

1.2.10

Interface Options

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

. . . . . . . . . ... oo
oL,

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

1.3

TECHNICAL CHARACTERISTICS

1.4

OPTIONS

CHAPTER 2

INSTALLATION AND CHECKOUT GUIDE

2.1

GENERAL

2.2

UNPACKING AND INSPECTION

2.3

PACKING PROCEDURE

2.4

EASY IDENTIFICATION OF LOGICBOARDS

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

. . . .

. . . . . . .
e
e
. . . . . . .. ...

. ... ... ... e

.. . ... ....

e e e e e e

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

JUMPER CONFIGURATION

2.7

M7723

JUMPER CONFIGURATION

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

2.8

M7728

JUMPER CONFIGURATION

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

2.9

LA36 CHECKOUT AND ACCEPTANCE PROCEDURES

. ... ... ...

2.10

LA35 CHECKOUT AND ACCEPTANCE PROCEDURES

. .. ...
.. ..

CHAPTER 3

OPERATION

3.1

LA36 OPERATOR CONTROLS AND INDICATORS

poed
ek

W=
O

= 00NN
——

ek fumd

fed pumd

pmd pemed

pemed

[—

M7722

INTERFACE INSTALLATION

2.6

2.5

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

POWER ON/OFF Switch

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

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

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

LINE/LOC Switch

. . . . . . . .

FDX/HDX Switch

. . . . . . . . .

e
o

. . . . . . . . . . .

ALT CHARSET Switch

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

. .«

.
.

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

STD/ALT CHARACTER SET Indicators
AUTOLF Switch

. . . . . . . . .

HERE IS Switch

. . . . . . . . . . .

PAPER OUT Indicator

... ..

e e e e

BAUD RATE Switches

CHARSET LOCK Switch

.
e e s s

... ...,

.. ...

. . . . . . . ... ... ...
e e s
o

. . . . . . . . . . . . . . . . . o .

DEVICE SELECT Indicator

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

SELECT AVAIL Indicator

. ...
.. .. e

CTRL Key

e e e e e e e e e e e e

CONTENTS (CONT)

Page

3.1.14

CAPSLOCK Key

3.1.15

SHIFT Key

. . . . . . i i

3.1.16

TABKey

.. ... ... e

3.1.17

ESC(SEL)Key

. . . . . i i i

3.1.18

REPEAT Key

. . . . . & i i

3.1.19

RETURNKey

... ... ... ..... e

3.1.20

LINEFEEDKey
BACKSPACEKey
DELETEKey
. .
BREAKKEY . . .
NumericKeypad
Bell
. . .

3.1.21
3.1.22
3.1.23
3.1.24
3.1.25
3.2

3.2.1
3.2.2

3.23
3.24
3.2.5

3.2.6
3.3

3.3.1
3.3.2

3.3.3

3.34

3.4

3.4.1

3.4.2
34.3
344
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

. . . . . . @ i i i it e

.
.
.
.
.

e e

e e e e e e e e e e e e e

e e e e e e e e e e e e e e

3-3

e e

3-3

e e e e e e e e e e e e e e e e e e e e

3-3

. . . . . @ . @
. . . . . i i
. . @ @ i
i
@ i i it it e
. . . . . . . .
e
e

e e e e e e e e e e e e e

e e

3-3

e e e e e e

e e

3-3

e e e e e e e e e e e e

i i i i e e e
i i i e e e
e et e e e
e e e e e e e
. .
o
o
e e e e e e e

e e e e e e

e e e e e e e e e
e e e e e e e e e
e e e e e e e e e
e e e e e e e e
e
e e e e e e e e

34
34
34
34
3-5
3-5

LA35 OPERATOR CONTROLS AND INDICATORS
. .. ... ...... 3-6
LINE/LOCSwitch . . ... .. .. ... e
e e e e e e e e e
e 3-6
BAUD RATE Switches
. . . . . . . . . . i i i v v it i v i v v e 3-6
PAPER OUT Indicator
. . . . . . . .« i i i e i i e e e e e e e 3-6
POWER ON/OFF Switch
. . . . . . . . . . .« . v, 3-6
HEADOFFORM Switch
. . . . . . . . . . . . ..., 3-6
Bell
. . . .
e e
e e e e e e e e e e e e e e e e - 3-6
LA36/LA35 COMMON CONTROLS
. . . . . . . . .
v v oo 3-7
Carriage Adjustment Lever
. . . . . . . . . . ... .. 0o 3-7
Paper AdvanceKnob
. . . . . .. .. ..
o o000 3-7
Tractor Adjust Knob
. . . . . . . .. .. ... .. ... “ .. 3-8
Cover Interlock Switch
. . . . . . . . . . . ... o000 3-8
LOADING PAPER AND NEWFORMS . . . .. . . .. ... .. ... 39
Paper Positioning Procedure . . . . . .. ... .. e e e e e e e e e e 3-9
Impression Adjustment
. . . . . ... ..o 0oL o oo 3-12

. . . . . . . . . . ... ... ... 3-13
Horizontal Positioning Adjustment
Fine Vertical Positioning
. . . . . . . . . . . ... o o000 3-13
Reloading Paper . . . . . . . . . .«
v
e
e e 3-14
RIBBON INSTALLATION
. . . . . .
e e e e e et et e e e e e 3-15
DECwriter INTERFACE INFORMATION
. .. .. .. .. .. ... .... 3-18
. . Lo 000 oo 3-18
.
.
.
.
.
.
.
.
Description
Interface
Interface Specifications . . . . . . . . . .. .. o000 3-18
i it ittt i h e v 3-19
. . . . . . . .
PROGRAMMER’'SGUIDE
. . . . . .. .. ... ... ... .. 3-19
LA36 Programmer’s Information
. . . . . . . .. .. ... .. 3-19
Transmitting Characters and Commands
0 3-19
... ...
...
.
..
.
.
.
.
Special Command Keys
e e e e 3-19
e
e
e
e
it
CTRLEKeEY . . . . i i i i i i e et e et
i it ittt e 3-19
BREAK Key . . . . . . . . @
Receiving Characters and Commands . . . . . . . . . . . . ... ... 3-19

. . . . o i i e e e e e e e e e e et e e e e e e e e e 3-23
USING THE LA36
. . . o o i e e e e e e e e e e e e e e e e e e e e e 3-24
USING THE LA3S
e e h e e e e e e e 3-24
TROUBLESHOOTING . ... ... ....... e
1v

CONTENTS (CONT)

Page

CHAPTER 4

THEORY

4.1

PROGRAM DESCRIPTION

4.1.1

ScratchPad Memory

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

e e e e e e e e e e e

. o i i i e

e e e e e e e e e e

4.1.2

Initialize (INIT) Routine

. . . . . . . . . . . . . . . o

4.1.3

Position (POSIT) Routine

. . . . . . . . . . .

4.14

SERVORoutine

. . . . . . . . . @ i i i i it it e ettt e e e

4.1.5

SPEED Routine

. . . . . . . . . & i i i i e e

4.1.6

INPUT Routine

. . . . . . . . i i i i e e e e e e e e e e e e e e

4.1.7

BELLRoutine

4.1.8

PRINT Routine

. v

v v v v

e e e

.. ... ... .. e

4.1.9

LINE FEED (LF) Routine
LCV Routine
NEXT Routine
TIMING

4.3

M7722/M7723 CONTROL LOGIC

4.4

KEYBOARD SYSTEM

4.5

DATA COMMUNICATIONS INTERFACE

. . . . .

e e

4.5.1

20mA Loop Receiver

4.5.2

20mA Loop Driver

e e

i e e e e e

e e e e e e e e e

. . . . . . . . .«

. . . . . . .

e e e

e e

i it e i e e

e e e e e e e e e e e e

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

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

e e e

. . . . . . . .

e e e

e e e e e e e e e st e e e

e e

4.6

CLOCK LOGIC

4.7
4.8

UNIVERSAL ASYNCHRONOUS RECEIVER/TRANSMITTER (UART)
CHARACTER BUFFER/GENERATOR AND PRINT HEAD SYSTEM

4.9

CARRIAGE SERVOSYSTEM

. . . . .

. . . . . . . . .

i e it it e

4.9.1

Tachometer, Summing Network, and Sum Amplifier

4.9.2

Encoder and Threshold Detector

49.3

Encoder Signal Detector

494

Column Increment Counter and Carry/Borrow Generator
BELLSYSTEM

4.11

LINE FEED STEPPER SYSTEM

4.12

WAKE-UP (WU) CIRCUIT

4.13

POWER SUPPLY AND REGULATOR

4.14

PRINTER MECHANISM

4.14.1

e e e

. ...
... ..

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

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

4.10

e e e e e e e e e e e e e e e

. . . . . . . . . . @ i i i i

4.2

e e e e e

. . . . . . . . . i i i i i i e e et e e e e e e

4.1.10

4.1.11

v v v v ..

...

. . . . . . . .

. © « o o vttt e e e e e e e e e e e e

Carriage Subsystem

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

. . . . . .

e e

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

Ribbon Feed Subsystem

4.14.3

Paper Feed Subsystem

e s e e e e e e

e e e e e e e e

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

CHAPTER 5

UPGRADED LA36

5.1

GENERAL

5.2

LA35/LA36 MODEL VARIATIONS

5.3

EASY IDENTIFICATION OF LOGICBOARDS

. . . . .

e e et e et e e

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

. . . . . . . . o

4.14.2

. ...,

e e e e e

...

e e e

. . . . . . . . . .« i,
. . ... ... .......

5.3.1

Major Functional Differences Between M7722 and M7723
LogicBoards
. . . . . . . . . . @ . i
e e
e

5.3.2

M7722, M7723, and M7728 Jumper Configurations

e e e e

CONTENTS (CONT)

5.3.3

Functional Differences Between M7723 and M7728 Logic Boards

5.3.4

M7728 Cabling Configurations/Option Combinations

5.4

MAJOR POWER SUPPLY CHANGES

5.4.1

New Power Transformers

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

5.5

NEW KEYBOARD BEZELS

5.6

CAPSLOCK KEYBOARD

5.7

LA35/LA36 OPTIONS

5.8

DECwriter II — M7728 FUNCTIONAL DESCRIPTION

5.8.1

..........

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

. . . . . . . .

. . . . . . .

e e

e e e e e e e e e e
. ...
.. ... ..

New Transmit Path

. . . . . . . . . . . . ... ... . . ... ...,

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

5.8.2

New Receive Path

5.8.3

Transmit Operation with Options Installed

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

5.8.4

Receive Operation with Options Installed

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

CHAPTER 6

ELECTRICAL SERVICING

6.1

ELECTRICAL TESTS
-

. . . . . . . . . . . @ i i

Servo Speed Test
Bell Test

Printable Character Test

On-Line Tests

e e e
e

e e

e s e
e e

e e
.

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

. . . . . . . .

e e e

. . . . . . . . . . @ @ i

e e e e e e

Current Loop Interface UART and Character Buffer Test

6.1.2.2

Serial Line Interface
Wake-Up Test

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

e e

TROUBLESHOOTING CHARTS (ON-LINE TESTS)

CHAPTER 7

MECHANICAL SERVICING

7.1

GENERAL

7.2

PRINTER HOUSING

. . . .

. . . . . . .

7.2.1

Printer Housing Removal

7.2.2

Printer Housing Installation

PRINT HEAD ASSEMBLY

7.3.1

Print Head Removal

7.3.2

Print Head Installation

7.4

TIMING BELT

Timing Belt Installation

7.5.1
7.5.2

7.6

7.6.1

e e e e

et e e e

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

e i

e e e e

... . .

...

. . . . . . ... ... ........ e e e

. . . . . . .

Timing Belt Removal

7.5

e e e e e

e e

. . . . . . .

7.4.2

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

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

7.4.1

. . . . .

. . . . . . . . . . .. .. ... ... ...,

6.2

7.3

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

6.1.2.1

6.1.3

e e

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

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

Line Feed (LF) Stepping Test

d.
2

o e

Encoder Signal Processing Test

Off-Line Tests

Sy
g N

AN
O\

6.1 1

. . . . . . .

e e

e e e e e e e e e e e

. . . . . . . .. .. .. ... ... .. ...,

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

CARRIAGE ASSEMBLY AND CARRIAGE SHAFTS
Carriage Assembly and Carriage Shafts Removal
Carriage Assembly and Carriage Shaft Installation

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

CARRIAGE BUSHING AND CARRIAGELEVER

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

Carriage Bushing and Carriage Lever Removal

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

CONTENTS (CONT)

Page

7.6.2

7.7

7.7.1
7.7.2
7.8

Carriage Bushing and Carriage Lever Installation
RIBBON DRIVE ASSEMBLY

Ribbon Drive Assembly Removal
Ribbon Drive Assembly Installation

7.8.1

Ribbon Drive Fafnir Removal

Ribbon Drive Fafnir Installation

7.9.1
7.9.2

7.10

. . . . . .. ... .. ... ....... 7-18
. . . .. . .. ... ... ... ... 7-20

RIBBON ECCENTRIC WITH CLUTCH/BACKSTOP SPRING

RIBBON DRIVE PULLEY

. . . . . . .

Ribbon Drive Pulley Installation

7.11

DC MOTOR AND ENCODER ASSEMBLY

o e

e e e i

. . . .. . . . ... ... ...... 7-21
. . . . . . . . .. ... ..... 7-22

DC Motor and Encoder Assembly Removal

7.11.2

DC Motor and Encoder Assembly Installation

7.11.3

Encoder Electrical Adjustment

. . . . . .. .. ... .. 7-23

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

PRINTER MECHANISM ASSEMBLY

. . . ... .. ... ... ... 7-26

. . . . .. ... ... ... ...... 7-27

TRACTOR DRIVE SHAFTS AND TRACTOR ASSEMBLIES

7.13.1

Tractor Drive Shaft and Tractor Assembly Removal

7.13.2

Tractor Drive Shaft and Tractor Assembly Installation

7.14.2

7.15

7.15.1
7.15.2
7.16

RIBBON CHASSIS ASSEMBLY

Ribbon Chassis Assembly Installation

... 7-31

... ... .... 7-31

. . . . .. . . ... ... .... 7-31

. . . . . .

. . . . . 7-33
e 7-34

. . . . . . . . . . . . . ... . ..o 7-34

IDLER GEAR ASSEMBLY

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

. . . . . . .

Idler Gear Assembly Removal

Idler Gear Assembly Installation

STEPPING MOTOR ASSEMBLY

0. 7-35

e e, 7-37

. . . .. . .. ... ... ...... 7-37

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

Stepping Motor Assembly Installation
TRANSFORMER ASSEMBLY

. . . . ... .. ... ... ....... 7-37

Stepping Motor Assembly Removal

7.19.2

. .

. ...

Ribbon Spool Ratchet Wheel(s) and Friction Disk Installation
PRINT BAR

7.18.2

7.19.1

. . . . .. 7-32

7.18.1
7.19

. . . .. .. 7-32

Print Bar Installation

7.18

. . .. ...
. 7-29

Ribbon Spool Ratchet Wheel(s) and Friction Disk Removal

Print Bar Removal

7.17.2

. .

. ...
.. .. 7-29

. .. .. ...
. 7-29

RIBBON SPOOL RATCHET WHEELS AND FRICTION DISKS

7.16.1

7.17.1

. . . . . . . . . .

Ribbon Chassis Assembly Removal

7.16.2

7.17

... 7-23

. . . . . . . . .. ... .. ..... 7-26

Printer Mechanism Assembly Removal
Printer Mechanism Installation

. . . . . ... .. .. ... 7-22

7.13

7.14.1

e e e e 7-21

. . . . . . . . ... ... ........ 7-21

7.11.1

7.14

. ...
.. .. 7-20

Ribbon Eccentric with Clutch/Backstop Spring Removal . . . . . . .. 7-20
Ribbon Eccentric with Clutch/Backstop Spnng Installation . . .. . .. 7-20
Ribbon Drive Pulley Removal

7.12.2

e 7-16

. . . . . . ... ... ... .... 7-17

7.10.2

7.12.1

e e

.. . .. .. .. ... ... ..... 7-18

7.10.1

7.12

e e e

. . . . . ... ... ... ...... 7-16

RIBBON DRIVE FAFNIR BEARING

7.8.2
7.9

. . . . . .. ... .. 7-15

. . . . . . . . . .

... 7-38

. . . . . . .. ... .. ...... 7-38
. . . .. ... .. ... ..... 7-38

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

Transformer Assembly Removal

..., 7-39

. . .. ... .. ... ......... 7-39

Transformer Assembly Installation Procedure

. . . . . . ... ... .. 7-43

LINE FILTER ASSEMBLY AND FUSEHOLDER

. ... ... ....... 7-44

7.20.1

Type 1 Line Filter and Fuse Holder Removal

. . . . . ... ... ... 7-44

7.20.2

Type 1 Line Filter and Fuse Holder Installation

7.20

. . . ... .. ... .. 7-44

CONTENTS (CONT)

7.20.3

Type 2 Line Filter and Fuse Holder Removal

7.20.4

Type 2 Line Filter and Fuse Holder Installation

7.21
7.21.1

7.21.2
7.22

LKO02, LKO3 KEYBOARD ASSEMBLY AND FRONT PANEL ASSEMBLY
Keyboard and Front Panel Assembly Removal

LKO02 Keyboard Assembly Installation
POWER BOARD

. . . . . . .

e e

. . . . . . . . . . .. ... .. . . . .00

7.22.1

Power Board Removal

7.22.2

Power Board Installation

7.23

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

LOGICBOARD

e e e e

. . . . . .

e e e e

e e e e e

e e e e e e e

7.23.1

Logic Board Removal

. . . . . . . . . . ... ... ... .. ...,

7.23.2

- Logic Board Installation

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

CHAPTER 8

ADJUSTMENT PROCEDURES AND LUBRICATION

8.1

GENERAL

8.2

ENCODER ADJUSTMENT

8.3

PRINT HEAD ADJUSTMENT

8.4

CARRIAGE SHAFT ADJUSTMENT

8.5

PRINT BAR ADJUSTMENT

. . . . . e
e
e e e
. . . . . . . . . ..

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

. . .. ... ...

...

8.6

PAPER GUIDE AND PRINTER MECHANISM ADJUSTMENT

8.7

PAPER OUT SWITCH ADJUSTMENT

8.8

RIBBON TENSION ADJUSTMENT

8.9

RIBBON DRIVE ASSEMBLY ADJUSTMENT

8.10

IDLER GEAR ASSEMBLY ADJUSTMENT

8.11

BUMPER ASSEMBLY ADJUSTMENT

8.12

LUBRICATION

APPENDIX A

ENGINEERING DRAWINGS

APPENDIX B

ILLUSTRATED PARTS BREAKDOWN

APPENDIX C

REFERENCE DATA

C.1

ABBREVIATIONS

C.2

SIGNAL GLOSSARY

C.3

IC PIN LOCATION DRAWINGS

. . . . . .

. . . o

. . ... .. ... .. ..... e

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

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

0., .

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

st e s e

e e e e e e e e e e e

. . . . o o

e e e e

e e

e e e e

e e e e e e e e

. . . . . . .

e e e e e

e s s e e e

FIGURES
Title

Figure No.

Outline DIMeENSIONS

. - + - « & ¢ ¢ v v e v e e e e e e e e e e

e e e e e e

Simplified Functional Block Diagram . . . . . . . . ... .. ... ... ..
Current Loop Cable Connector Pin Designations
|
Standard Current Loop Interface
Optional Current Loop Configurations

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

Vil

FIGURES (CONT)

Figure No.

2-1

LA36 Site Considerations

. . . . . . . . . . . . . . .. e

2-2

LA35 Site Considerations

. . . . . . . . v v v it e

e e e

2-3

DECwriter Packaging

. . . . . . . . . . . . . i

Cable Tie Location

. . . . . . . . . . . i i i i e e

2-5

Physical Characteristics of M7722, M7723, and M7728 Logic Boards

2-6

DECwriter Current Loop Cable Connection

e e e e

e e e e e e e e e e

. . . . .

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

2-7

DECwriter DEC10 Current Loop Cable Connection

2-8

DECwriter EIA Logic Board Connection

Acoustic Coupler Cable Connection

2-10

Location of Jumpers on M7722 Logic Board

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

2-11

Location of Jumpers on M7723 LogicBoard

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

2-12

Location of Jumpers on M7728 LogicBoard

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

4-1

Microprogram Flow Diagram

4-2

INIT Routine

4-3

POSIT and START Routines

4-4

SERVORoutine

. . . . . . . . . @ i i

4-5

SPEED Routine

. . . . . . . . . . . i

4-6

INPUT Routine

. . . . . . . . . . o o i

4-7

BELL Routine

. . . . . . . . . . . . . @ @

4-8

PRINT Routine

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

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

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

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

. . . . . . . . . .

e e e

e e e e e e e e e e e

. . . . . . . . . . .
i

e e e

. . . . . . . . . . .

e e e e e e e
e

v v
e e

e e

..
e

e e e e e e e e e e e e

e e

e e e e e e e

e e

e e e e e

4-9

LINE FEED Routine

4-10

LCV Routine

. . . . . . . @ @ @ i i it

4-11

NEXT Routine

. . . . . . . . . . . @

4-12
4-13

Control Logic Block Diagram
. . . . . . . . .. . .. .. ... . ......
LKO02/LKO3 Keyboard Logic Diagram
. . . .. ... ... .........

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

e e

i e

4-14

Keyboard Timing Diagram

4-15

Data Communications Interface Diagram

4-16

Data Communications Interface Timing Diagram

4-17

20 mA Loop Receiver Diagram

4-18

20mA Loop Driver

4-19

Clock Logic

4-20

Clock Timing Relationship

4-21

e e

i i i i i

e e e e

e e

e e e e

e e

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

...

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

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

. . . . . . . . .

. . . . . . .« o i i i

e e e e e e e e e e e e

e e e e e e e e e e e e e e e e e e e

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

4-22

UART/Mode Selection and Baud Rate Selection Logic
. . . . ... ... ..
Character Buffer/Address Register/Generator and Print Head System

4-23

CGROMCharacterCell

4-24

Print Head Operation

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

4-25

Carriage Servo System

. . ..
. .. e

4-26

Tachometer Logic

4-27

Encoder and Threshold Detector

4-28

Encoder Signal Detector

4-29

Increment Detection Timing

4-30

Encoder Signal Detector and Column Increment Counter Timing Diagram

4-31

Column Increment Counter and C/B Generator Logic

4-32

Bell System Logic

. . . .. .. ... ... .. ...
. i i i i i

...,
i i e

e e e e e e e e e e e e e e e e e e e

. . . . . . . . . . . . . @ @

i i i i it

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

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

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

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

FIGURES (CONT)
Title

Figure No.

Page

4-33

Line Feed Stepper System

4-34

Line Feed Timing Diagram

4-35

Power Supply Block Diagram

4-36

LA36 Printing Principle

4-37

Carriage Subsystem

4-38

Ribbon Feed Subsystem

4-39

Paper Feed Subsystem

5-1

Physical Characteristics of M7722, M7723, and M7728 Logic Boards

5-2

Cabling Configurations for the M7728 Logic Board

5-3

LA36 Keyboard Bezel

5-4

Basic Block Diagram of M7728 LogicBoard

5-5

M7728 Control Logic Diagram

5-6

Steering of Keyboard Data

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

.. 4-47

. . . . . . . . . .. ... ... . ........ 4-48

. . . . ... ... ... ... ... .. .... 4-49

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

. . . . . . . . . ..

e 449

e e e e e e e e e e e e e e 4-50

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

.00, 4-51

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

. . . . . . . . . . @

. 4-51

. . . . .

5-2

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

5-3

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

@ @ i i

e e

5-5

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

5-7

. . . . . . . . . . . ... .. 000,

5-8

5-7

Receive Operations of M7728 LogicBoard

6-1

Encoder +21 VTest Setup

. . . . . . . . .

6-3

Encoder-21 VTestSetup

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

6-4

+PT1 and +PT2 Waveforms
. . . . . . . . o i i i e e e e e e e
e e
+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
. . . . . . . .
o i e e e e e e e e e e e e e e e e e e
+TACH Waveform . . . . . . o o o e e e e e e e e e e e e e e e e e e e e
-PT1 and -PT2 Waveforms
. . . . . . . . . « o« i v v v v v v v oo...
-PT1 and -PT2 Schmitt Waveforms . . . . . .. . ... ... ... .....
-INC and COUNT Flip-Flop Waveforms
. .. . . ... .. ... ......
-INC Waveform . ... ... .. .. ... e
e e e e e e e e e
e e e e
~-TACH Waveform . . . . . . . .
e e e e e e e e e e e e e e e e e e e
-INC and 76 us CLOCK Waveforms . . . . . . . . . . .« .. v
-TACH Waveforms at Q12-Band Q12-C
. . . . . . . . . . . ... ... ..
~-TACHand 76 us Waveforms . . . . . . . . ¢ v v i v v v i e e e e e e
-TACH and SUM WaveformsatJ1-B
. . . . .. ... ... ... ...
~-TACH and MD Waveforms . . . . . . . . o« v v v v v it et e e e e e

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

6-2
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

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

. . o @ i i v i v

6-22

INCWaveform . . . . . v v v o e e e e e e e e e e e e e e e e e e e e e e 6-14
COL INC COUNT 3 (MSB) and COL INC COUNT 2 Waveforms
. ...
. .. 6-15
COL INC COUNT 3 (MSB) and BORROW H Waveforms
. ...
.. ... .. 6-15

6-23

+INCand 76 us Waveforms

6-24

+TACHand 76 us Waveforms . . . . . . . . . .« . o v
+TACH Waveforms at Q11-Band Q11-C
. . . . . .. .
+TACH and SUM Waveforms
. . . . . . . .« ¢ v v v
+TACH and MD Waveforms . . . . . . . . .«
v v v
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 TPA15S
LF1 Waveform at TPA13 and LF2 Waveform at TPA16

6-20

6-21

6-25

6-26
6-27
6-28

6-29
6-30
6-31

. . . . . . . . .« i v i i e e

e e e

e 6-16

v v v v v v v v v 6-16
... ... ..... 6-17
v v vt v e
e e e 6-17
v v v v v v v v v 6-18
. . ... ... ... 6-18
. . ... .. .. .. 6-19
. . . ...
.. ... 6-20
. ...
.. ... .. 6-20

FIGURES (CONT)
Title

Figure No.

Page

6-32

LF1 Waveform at TPA14 and LF2 Waveform at TPA17

. . ...
... .. 6-21

6-33

LF Motor Common Return and LF HOLD Waveforms

. . .. ... ... .. 6-21

6-34

LF1 Waveform at J1-JJ and LF2 WaveformatJI1-P

6-35

LF1 Waveform and LF HOLD Waveforms

. . . ... .. .. ... .. .... 6-22

6-36

BELL Source and BELL SINK Waveforms.

. .. . ... ... .. ...... 6-23

. .. .. ... .. .... 6-22

6-37

BELL SINK and BELL Waveforms

6-38

KBH H Pulse Waveforms

6-39

HD EN and SOL WaveformsatlJ6

6-40

HS1 and SD1 Waveforms

. . . . . . . . . . .

6-41

HS1 and SD1 Waveforms

. . . ..

6-42

HS1 and SD1 Waveforms

. . . . . . . . . . . . o i i e 6-27

6-43

HS1 and SD1 Waveforms

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

6-44

HD EN and HS1 WaveformsatJ1

6-45

HD EN and BUFF HEAD EN H Waveforms

6-46

HD EN Voltage Waveform and SD Current Waveform

6-47

WRITE BUFF L and CLR R DONE Waveforms

6-48

KEY STB L Waveform

6-49

Power Board V REF Waveform

. . . . . . . . . . .. ... ... .. .... 6-32

. . . . . . . . . ... .. ...« ..... 6-24

. . . . . . . . . . .

. o o v i i s 6-24

. . ... .. ... ... ... ....... 6-26

. .

@ e 6-26

. . . . . . . . .

.. ... 6-27
6-28

. . ... .. ... ... .. ... ..... 6-29
. . .. ... ... ... ..... 6-30
. . .. ... .. .. .. 6-30

. . . .. ... ... ..... 6-31

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

i e i

.. 6-31

6-50

CLKHand 592 nsWaveforms

. . ... ... ... .. . ... .. ...... 6-32

6-51

592 nsand 1.184 us Waveforms

. . . . . . . . . . . . . .. ... .. .. .. 6-33

6-52

9.4 usand 76 us Waveforms

6-53

94 usand 19L us Waveforms

. . . . . . . . . . . . . . . 6-34
. . . . . . . . . . . ... ... 6-34

. . . . . . . . ...

e 6-33

6-54

188 usand 76 us Waveforms

6-55

18.8 usand 4.8 kHz Waveforms

. . . . . . . . . . . . . . ... 6-35

6-56

208

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

Hand 4.8 kHz Waveforms

... ... .... 6-35

6-57

37.6 usand 1.76 kHz Waveforms

. . . . . . o . v v v v e 6-36

6-58

M7728 Option Clock Waveform

. . . .. ... .. ... ... ... ..... 6-36

6-59

Current Loop Test Setup

. . . . . . . . . . . . . . . . .. 6-38

6-60

Loop Receiver Waveforms

. . . . . . . . . . ... ... . ... ..... 6-39

6-61

Loop Driver Waveforms

. . . . . . . . . . . .. .. . ... .. ... ..., 6-39

6-62

Serial Line Test Setup

6-63

Serial Output and Serial Input Waveforms

6-64

Wake-Up Waveform

6-65

Example of Lost Position (reduced 50 percent)

. . .. ... ... ... ... 6-53

6-66

Print Head Solenoid Resistance Measurement

. . . . . . . . . ... ... .. 6-54

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

6-41

. . . . . ... ... ... ..... 641

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

. 6-42

6-67

Typical Voltages for Power Supply Regulators

7-1

Assembly Removal Sequence

7-2

Printer Housing Removal

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

7-3

Power Board Connectors

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

Print Head Removal

7-5

Print HeadCable

. . . . . ... .. ... ... .. . ... ... ... ..
. .. .. .. ... ........... e
e e e e e e

7-5
7-6

7-6

Print Head Adjustment

7-7

Belt Tension Spring Location

7-8

Carriage Shaft Screw Access

. . . . . ... ... ..... 6-55
. . . . . ... ... ... ... ........
7-2

. . . . . . . .. .. ... . ... ... . . ...,
. . . . . . .. . .. . . .. ... .......
. . . . . . . . . . o ot

7-7
79
7-10

FIGURES (CONT)
Figure No.

Title

Page

7-9

Carriage Shaft Removal

7-10

Printer Mechanism End Plate Loosening

7-11

Carriage Shaft Parallelism/Alignment

. . . . . . .. ... .. ... ..... 7-13

7-12

Plain Bushing and Spring Replacement

. . . . . . .. ... ... ...... 7-15

7-13

Carriage Lever and Eccentric Bearing Replacement

7-14

Ribbon Drive Assembly Removal

. . . . . . . .. .. ... .. . ... .. ...... 7-11

7-15

Ribbon Drive Adjustment

7-16

Fafnir Bearing Removal

. . . . . . .. ... .. ... .... 7-11

. . . . . . ... ... .. 7-15

. . . . . ... ... ... ......... 7-16

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

e 7-18

. . . . . . . .. . ... ... ... .. ... ..., 7-19

7-17

Ribbon Drive Shaft Adjustment

7-18

DC Motor/Encoder Cabling

7-19

DC Motor/Encoder Removal

7-20

Encoder 50 Percent Duty Cycle Waveshape

. . . . . . . ... .. ... ... ...... 7-19

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

.. 7-22

. . . . . . . . . . . . . 0 i i

. 7-22

. .. ... ... ......... 7-24

7-21

Encoder (Rear View)

7-22

Encoder Phasing Adjustment

7-23

Printer Mechanism Removal Preparation

7-24

Printer Mechanism Removal

. . . . . ... ... ... ... ......... 7-26

7-25

Printer Mechanism Alignment

. . . . .. .. .. ... .. .......... 7-28

7-26

Printer Mechanism Adjustment

. . . . . . . ... . ... ... ... ..., 7-28

7-27

Tractor Removal

7-28

Tractor Phasing/Adjustment

7-29

Ribbon Chassis Removal

7-30

7-31

Ribbon Threading/Drag Test
. . . . . . . . . . . . . . . ...
. .... 7-32
Friction Disk/Ratchet Wheel Replacement
. . . . .. ... ... .. ... . 733

7-32

Print Bar Removal

7-33

Calibrate Alignment Gaugeand Block

7-34

Print Bar Alignment

7-35

Idler Gear Assembly Removal

7-36

Stepping Motor Removal

7-37

Transformer Removal

7-38

Capacitor C5

7-39

Rocker Switch S1

. . . . . . . . . . @

e e e

e e e e e e e 7-24

. . . . ... ... ............ ... 725
. ... .. .. ... ... ..... 7-26

. . . . . . . . . . . . . . . e 7-29

. . . . . ...
... e

e e

. . ... ... ... .. e

e e 7-30

e e e e e e e e e 7-31

. . . . . . . . . . . . . . . ... .. e 7-34

. . . ... ... .. ... ....... 7-35

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

. 7-36

. . . ... . . .. ... ... ... ..., 7-37

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

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

. . . . .

e e

e e e e

. . . . . . . .

oL, 7-38

..., 7-39

e e e e e e e e e e e e 741
e e

e e e e e e e 7-42

7-40

Type 2 Filter Assembly Removal

741

Keyboard Bezel Removal

. . . . . . .. . . ... ... . .. ... . ..., 7-46

. . . .. .. ... ... .......... 7-45

7-42

LK02 Keyboard Removal

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

... 747

743

LKO3 Keyboard Removal

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

... 7-48

7-44

L KO3 Keyboard and Control Pad Removal

8-1

Encoder 50 Percent Duty Cycle Wave Shape

. . . . ... . ... ... .... 7-49
. . . . ... ... ... ....

8-2

8-3

Encoder (Rear VieWw)
. . . . . v v i i i i e e e e e e e e e e e e e e e e
Encoder Phasing Waveshape . . . . . . . . . .. . ... 0o

8-3
84

e e e e e e e

8-5

8-4

Print Head Adjustment

. . . . . . . . . . . . i i

8-5

Timing Belt Removal

. . . . . . . . . . . . . . @

8-7

Carriage Shaft Parallelism/Alignment
. . . . .. . ... ... ... .... .
Alignment Gauge and Calibration Block . . . . . .. . ... ... ... ...

8-8
8-9

8-8

Print Bar Adjustment

. . . . . . . . ...

Xii

e e

e e e

e e

e 8-10

FIGURES (CONT)

Title

Figure No.

Page

Printer Mechanism Alignment

. . . . . . . . . . ... ... ... .. .... 8-11

8-10

Printer Mechanism Adjustment

. . . . . . . . . .. ... ... ... ..., 8-12

811

Paper Guide Adjustment

8-12

PAPER OUT Switch Adjustment

. . . . . . . . .. ... ... ....... 8-13

8-13

Ribbon Spool Tension Adjustment
Ribbon Threading/Drag Test
. .
Ribbon Drive Adjustment . . . .
Ribbon Drive Assembly
. . . . .
IdlerGear Assembly . . . . . . .

. . . . . . . . ... .. ... ...... 8-14
. . . . . & ¢ v v v v i it e e e et 8-15

8-14
815
8-16
8-17

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

. . . . . . . . . .

e 8-12

e e e e e 8-16

. . . .. ... ... .. oo 8-17
. . ..

e e

e e e e e e e 8-18

8-19

Bumper Assembly Adjustment . . . . ... ... ... ... .. S 8-19
Carriage Shaft Lubrication
. . . . . . . . . . . v v v i i e 8-20

8-20

Ribbon Drive Assembly Lubrication

8-18

. .. . . ... ... ... ....... 8-20

TABLES
Title

Table No.

Page

1-1

Standard ASCII Character SetandCode

ASCII Codesand Responses

1-6

1-3

Standard Full-Duplex 20 mA Current Loop Cable Connections

. . . . . . . .

1-11

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

. . . . . . . . . . . ¢ i v i v v i v i v e e

Optional Half-Duplex 20 mA Current Loop Cable Connections

1-5

Interface Port ConnectorPins

1-6

Technical Characteristics

1-7

Current Interface Specifications

1-8

LA360ptions

. . . . . . o i i

e e

LA35S0ptions

. . . . . . . i i i

3.1

ASCII Codes and Responses

1-2

. . . . . . . .

1-13

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

1-13

. . . . . . . . . . . . . . . v,

1-14

. . . . . . . . . . . . .. ... ... ...,

1-16

e e e e e e e e e

e e e e e e

1-17

e e e e e e e

1-20

. . . . . . .. e

e e e e e e e e e e e e e e 3-20

3-2

Operator’s Troubleshooting Guide

4-1

Scratch Pad Allocations

4-2

SPEED Algorithm

4-3

Keyboard ROM Addressing

4-4

Numeric Keypad ROM Addressing

. . . . . . ... ... ... ....... 4-31

4-5

Clock Frequencies and Time Periods

. . . . . . . . ... ... .. ..... 4-35

4-6

Baud Rate Switch Connections

4-7

MPC SPEED Command Truth Table

. . . . . . . . . . .. ... .. ..... 3-24

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

. ...
.. ... e

LF Pulse Truth Table

Test Equipment and Special Tools

6-2

UART Test

6-3

Character Buffer Test

4-5

e 4-10

v v v v

... 4-25

... 4-37

. . . . .. ... .. ... ... .... 441

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

. . . . . . . o

e e e e e

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

6-1

e ee... 448

. . . . . ... .. .. ... .......
e

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

TroubleshootingChart

. . . . . . . . . .« .« . o

4-8

6-4

e e e e e e e e e

e e

e e e

6-1

e 6-25

. i i i i i i e e e 6-25

. . . . . . . . . . .. ... .. .. ... .. ... 6-44

6-5

- DCSupply Voltages

8-1

LubricationPoints

B-1

Glossary of Abbreviations

B-2

Signal Glossary

. . . . . . . . . @ . @ i i i

e 6-54

. . . . . . . . . . . . . ... .. . e 8-20
. . . . . . . . . . .. .. ...

. . . . . . . L.

e e e

e e e e e e e e

B-2
B-5

TRACTOR

PAPER

ADVANCE

ADJUSTMENT
KNOB

RIBBON SPOOLS

KNOB

PRINTER
oFr

nONe

Cnat
S£Y

e "B I

CARRIAGE ADJUSTMENT

OPERATOR

LEVER

CONTROLS

LA36/LA35 DECwriter

8433-17

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
of fill 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 Kkey.

1-1

Table 1-1

Standard ASCII Character Set and Code

|o0o0o0

e | DB
L1l

BIRI

r]eere

LA T

la|la|leee

ci|L]leroo
| @]

Al
Sl&EIF

(1BIH|

Tlwler

e
eeo

LY| w

o ee

(KLl

I I A I B

d{m|

RNy

1-2

1.1 PHYSICAL CHARACTERISTICS
|
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 11 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

27.5"

(696mm)

LA36

LA35

—>

}

33 5"

33.5"

(852mm)

21.7"

(551mm)

‘

24.0"

(610mm)

25.0"

(635mm)
cP-1871

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

MICRO-

CRYSTAL

| 1.6896MHz

CLOCK

2.4KHz

SYSTEM

LF/LF HOLD

LINE FEED
STEPPER

PROGRAMMED

SYSTEM

CONTROLLER
(MPC)

CARRY/ BORROW

SPEED DATA

DATA BUS

INCREMENT

CARRIAGE
SERVO
SYSTEM
|
|
|

CHARACTER|

ADDRESS

INPUT

F—|

COMMUNICATIONS

woor

ADDRESS REGISTER

UART

Loopr

CG ROM

| RECEIVE

“SERIAL

Ac
x

DATA

INTERFACE

SERIAL

A
B

KEYBOARD

LA36 ONLY

SYSTEM

STROBE

RIBBON

DRIVE
SYSTEM

PRINT HEAD

COLUMN

INCREMENT COUNT

'
CP-1378

Figure 1-2

1.2.1

Character Prmtlng

Simplified Functional Block Diagram

At power-up, the print headis 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 columnis set about
3.8 mm (0.15 inch) to the right of the end stop.

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 1s 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 1b/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 OPERATIONS

RECEIVE OPERATIONS

To Transmit, Type Key(s) (LA36)
Character

ASCII Code | Character

SHIFT*

CTRL*

CHAR

Printed

Action/Description

Vv
Vv
Vv
v
vV
Vv
Vv
v
v
v
Vi
Vv

SPACE
A
B
C
D
E
F
BELL
H
I
J
VT

None
P

None
P
|
|
|
v
None
Sound Alarm Bell
Backspace one position
None
Advance Paper one line
None

000
001
002
003
004
005
006
007
010
011
012
013

NUL
SOH
STX
ETX
EOT
ENQ
ACK
BEL
BS
HT
LF
VT

014

None

015
016
017
020
021
022
023
024
025
026
027
030
031
032
033
034
035
036
037
040

CR
SO
SI
DLE
DC1
DC2
DC3
DC4
NAK
SYN
ETB
CAN
EM
SUB
ESC
FS
GS
RS
US
SP

WV
Vi
v
Na
Vv
v
Vv
v
vV
N/
v
v
N
vV

M
N
O
P
Q
R
S
T
U
\%

Move print head to left margin
None
&

v
v
vV
v

[
\

v
v

W
X
Y
y/

=
~
—
space bar

None

Blank Spacd | 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)
Character
Character

041

042

[X)

043
044

045

046

SHIFT*

CTRL*

KINISKIK
<

ASCII Code

CHAR

Printed

Action/Description
Print character, move print head

one position to the right.

”n

047
050

051
052
053

076
077
100

101
102

103
104

O]
=
AW
NI
0O
1N

]

=
LWL
]
QIO
O] 0o

AN b

075

wh (@ 1= kg FON indl AVA NN

074

073

072

wh (o] 151 B-d NOF hnd AVA BN VAN hh

071

i (o] 1+ I 4 NON indl AV

070

|«

066

067

065

064

< el

062
063

HlWI}

061

060

Q] O

057

O] oo}

056

=] O] T}

055

054

Print character, move print head

one position to the right.
_an

*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.

Table 1-2

ASCII Codes and Responses (Cont)

- KEYBOARD OPERATIONS

RECEIVE OPERATIONS

To Transmit, Type Key(s) (LA36)

136
137

140

141
142

143

144
145

146
147

150

QT &
H]|»| RO

F|OIZIZ|C| AR T TR

one position to the right.

gl <]

TR
R|
ZI ||
RO] PO
PR
R E]l <]l

Ni=< X

135

A 11> =]

134

Print character, move print head

o] o'l &

133

Action/Description

= lo

132

131

130

A1 1>l

126
127

125

123
124

O] O

121

122

Printed

QT |m

120

CHAR

117

S LN LN L L L R L L L L L L L A AR L A A S A AU A

116

115

A =l Bl E=2 A

114

113

>3 bl B lm NI T R RS B (=1 ks

112

110
111

jaljo]lc|
e

107

CTRL*

106

SHIFT*

sjfoa |

105

9 Lt Kol Bl Bt =2 N0 el A

ASCII Code | Character

QT &

Character

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.

1-8

Table 1-2

ASCII Codes and Responses (Cont)

KEYBOARD OPERATIONS

RECEIVE OPERATIONS

To Transmit, Type Key(s) (LA36)
Character

[

155

156
157
160

161

162
163
164
165

166
167

170
171
172

<J<]<

173

174
175

176

w Qs o

154

Action/Description
Print character, move print head

vt w Sk o

153

Printed

one position to the right.

Iw,--mN'~<><g<::«-*wfl..D'oo=§

I Rl [t K | R B~ el et Nl B4 14 Rl Hall il e

CTRL* | CHAR

13 Raad i sl BNV IS IS

151
152

SHIFT*

Yto

ASCII Code | Character

DELETE

None

Print character, move print head

one position to the right.

177

DEL

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.

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 Servo 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 mV peak-to-peak maximum
ripple.
Regulated volts of +12 V +5 percent and -12 V +5 percent, with 500 mV 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 LA3S only utilizes the receive
circuitry.

The standard interface is a full-duplex, passive
20 mA current loop similar to a Teletype® 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

CP-nes

1-4 (polarities denote current flow).

®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

To Host Computer

Connector J3

Connector

P1-2

Circuit

P2-3

P1-5

Transmit (+)

Negative side

(keyboard)

of line

Transmit (-)

Positive side

(keyboard)

of line

Receive (+)

Negative side

(printer)

of line

Receive (=)

Positive side

(printer)

of line

P2-7

P1-3

P2-2

P1-7

P2-5

HOST (COMPUTER)
ACTIVE

Description

LA36

TRANSMITTER

PASSIVE RECEIVER

CURRENT

SOURCE

lxMrr

LM,___/.“.\J

XlflIT

INTERFACE
CABLES

,UPTO

{5,100 8L,
Iy — —-»
2

REC I
REC
+

20 MA

CURRENT

RCVR

DETECTOR

_TO

~ PRINTER

[

| see

—_—

| NOTE

TRANSMITTED
DATA

ACTIVE

RECEIVED
DATA

RECEIVER

PASSIVE

TRANSMITTER

H
W

CURRENT
DETECTOR [

rec

=== I

| REC
-

20MA
-

XMTR

I —— > #——l

3
|2

FROM

KEYBOARD

2 IXMIT
Pi|
*

CURRENT
SOURCE

cP-1167

NOTE: Loop switches are tranistors.

| Figure 1-4 Standard Current Loop Interface

Typing each specific key causes the LA36 transmitter switch to be opened and closed in a pattern that
defines the key.

The 20 mA communications circuit will operate wherever the current saurce 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 mA cable (BCOSF) 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 of the 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 I1
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
.

RECEIVE DATA
TO PRINTER|

AAA

];

-—————

XMIT

}Séggllxgla
I’"‘"T+

_______ _‘\’\] SEE NOTE

| DETECTOR

XMIT DATA
FROM KEYBOARD -

XMIT DATA
FROM KEYBOARD

l
CURRENT

}ACTIVE HALF
—
—* JDUPLEX PORT
_.T0

SEE NOTE

I
HALF DUPLEX
(ACTIVE)

ACTIVE RECEIVE

L
I

[REC \ 10 passIvE

REC [ TRANSMITTER
n

RECEIVE DATA

~_TO PRINTER
-

L
I

10
P pVE

|
I

DUPLEX PORT

RECEIVE DATA

TO PRINTER

| CURRENT

DETECTOR

L
NOTE: Loop switches are transistors.

Figure 1-5

#<_

SEE NOTE

o T

XMIT DATA
FROM KEYBOARD

Optional Current Loop Configurations

1-12

CP-164

Table 1-4

Optional Half-Duplex 20 mA Current Loop Cable Connections

Connector Pin Numbers
To Logic Board

To Host Computer

Connector J3

Connector

P1-5

P2-3

P1-3

1.2.9

Circuit

P2-5

Description

Transmit (+)

Negative side

(keyboard)

of line

Receive (-)
(printer)

Positive side
of line

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

Function

Unused

~12 V, up to 125 mA to optional interface

+12 V, up to 125 mA to optional interface

+5 V, up to 500 mA to optional interface

Serial output of LA36 to optional interface

TTL level, will drive 10 unit loads.

Mechanical

keying

plug

(no

electrical

connection).
7

Serial input to LA36 from optional interface

TTL level (must be capable of driving 10
unit loads).
8

Ground

1-13

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 mA 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 11 bit; 1 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 mA 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 1b) 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 (33.5in) H X 699 mm (27.5in) W X 607 mm (24 in) D
851 mm (33.5in) H X 699 mm (27.5in) W X 550 mm (21.7in) D
46 kg (102 1b)
44.09 kg (97 1b)

Environment
Temperature

Operating: 10° to 40° C (50° to 104° F)

Relative Humidity

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

Altitude
Ribbon

Non-operating: —-40° to 66° C (-40° to 151° F)

Operating: sea level to 3.04 km (8000 ft)
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

Maximum

Open circuit voltage (of circuit being driven)

50V

40V

Voltage drop, marking
Spacing current
Marking current

05V
0.4 mA
20 mA

20V
2.0 mA
80 mA

Minimum

Maximum

1.2V
0.0 mA
15 mA

2.7V
3.0mA
80 mA

Minimum

Maximum

1.7V
0.0 mA
15 mA

4.7V
3.0mA
80 mA

Receiver (passive, isolated)
Voltage drop, marking
Spacing current
Marking current

Cable
4-conductor
Standard 28.1 cm (15 ft) BCOSF-15 supplied with LA 36
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

APL /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

Options

Name

LA36 Options (Cont)

Switch/Indicator

Description

LAXX-KW

Selective
Addressing

DEVICE SELECT
and SELECT AVAIL
Lamps

The Selective Addressing Option
allows the LA 36 to communicate with
other terminals on a single data com- .
munications 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

DF11 Mounting Kit

None

The DF11 Mounting Kit enables the
user to mount one of the DIGITAL
series DF11 communication options
in the LA36.

1-18

Table 1-8
Options

Name

LA36 Options (Cont)

Switch/Indicator

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 DECI10.

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).

Scale, Pointer, and

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.

LAXX-LN

Window Kit

1-19

Table 1-9

Name

Option
LAXX-LB

LA3S5 Options

Expander Option
Mount

Description

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.

LAXX-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 pre-

set 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-KYV) and operates in the same manner.

1-20

Table 1-9

Option

LA3S Options (Cont)

Name

Description

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

DF11 Mounting Kit

The DF11 Mounting Kit enables the user to mount one of the
DIGITAL series DF11 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 mA current loop with Mate-N-Lok

LAXX-LK

Curent Loop Cable

20 mA current loop with 4-pin plug for DECI10

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.)
'

jo——o 24

27.5"

(696 mm)

—————1

27.5"

( 696 mm )

(635mm)

:
|

r — =

DIMENSIONS

]

e
ARE A
|

}-_—e-——-——fi

F___E"—“’

——

F———E————

O~ —~—

AREA

(635mm)

o \_;

—l
SERVICE

——————————

( 55imm)

alslclolelr

INCHES

335(275| 14 |24 | *|96

{

INCHES

7
2r3]
14 121 7 V* 36

MILLIMETERS

|[852(696|356(610(

MILLIMETERS

596[356] 551 |V

* |2440

* CURRENT LOOP CABLE (BCOSF) LENGTH
IS 15 FT ; EIA CABLE LENGTH IS 9 FT
(2744mm)

|
|

SERVICE

|
|

AREA

DIMENSIONS

AlBjc]|oD

15 FT, EYA CABLE

(2744 mm)

LENGTH IS

OFT

|
|

CP-2023

LA36 Site Considerations

[2440

CURRENT LOOP CABLE (BCOSF) LENGTH IS

Figure 2-1

21.7"
{ 551mm)

A—

L a
1.7

117

]

1.5"

(38mm)

—

[

SERVICE
AREA

|
|
J
cp-2021

Figure 2-2

LA35 Site Considerations

STRAPPING

\\ ?
FULL

TELESCOPE

—»

CAP

STITCHED
—
TUBE

|
POLYBAG —

wWOOD BRACE

HEX HEAD

———

TERMINAL

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.

Remove the outer cardboard shipping container.
Remove all shock-absorbing material and packing from around the DECwriter (Figure 2-3).
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 microfoam from around each leg of the DECwriter.

Carefully inspect the DECwriter cabinet, keyboard, and carriage assembly for possible ship-

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

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 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.

2.3 PACKING PROCEDURE
If it becomes necessary to ship your DECwriter to another location, repack it per the following
procedure.
1.
2.
3.

Remove the ribbon and paper.
Using a nylon cable tie, secure the print head assembly to prevent movement while in transit.
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.

SOLDERDOTS
TEST POINTS

e c0c0c00000cccocscsedooe

M7728

LOGIC BOARD

M7722

LOGIC BOARD

M7723

LOGIC BOARD

L7 = &F

evec0o00000000 000000

[

&F [

o.oooo/’ooooooooooooo

°
°
°

.
A H P
ooooooooofoooooooooo
5

CONNECTORS

CONNECTORS
CP-2391

Figure 2-5

Physical Characteristics of M7722, M7723, and M7728 Logic Boards

2-4

2.5

INTERFACE INSTALLATION

Connect one of the following DECwriter interfaces.
NOTE
For additional installation information, refer to the
LA36/LA3S DECwriter II User’s Manual, EKLA3635-OP-002.

e Current loop cable (see Table 1-7 for interface specifications); connect per Figure 2-6.
e DECIO0 current loop cable; connect per Figure 2-7.
e

EIA cable (LAXX-KG); connect per Figure 2-8.

e EIA cable (LAXX-LG); connect per Figure 2-8

e 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)

1 1 1 + S|Ol
umn~

Rl'l l alu

PINNING

L@)

wl|laoaoa

CP-2043

Figure 2-6

DECwriter Current Loop Cable Connect 10N

2-6

283B CONNECTOR

(TELEPHONE

o~ CONNECTOR)

CP-2042

Figure 2-7

DECwriter DEC10 Current Loop Cable Connection

2-7

STANDARD EIA MODEM - TERMINAL INTERFACE CONNECTIONS

SENTTO

NAME

FUNCTION

DATA TERMINAL

DATA

EIA CIRCUIT

EQUIPMENT

COMMUNICATIONS

DESIGNATION

(DECwriter)

EQUIPMENT

FRAME GROUND

TRANSMITTED DATA

RECEIVED DATA

RTS

REQUEST TO SEND (NOTE 1)

SIGNAL GROUND

DCD

DATA CARRIER DETECT (NOTE 2)

NONE

UNASSIGNED

NONE

DTR

DATA TERMINAL READY (NOTE 1)

RING INDICATOR (NOTE 2)

BA
.

X
X

X
X
X

NOTES:

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.

J4(PINNING 8-1)
(M7722, M7723,M7728)

||||

LAXX -KG or LG

PN '/%"“S\
N

TO USERS

EQUIPMENT

L P
CP-2046

Figure 2-8

DECwriter EIA Logic Board Connection
2-8

Figure 2-9 Acoustic Coupler Cable Connection

2-9

w12

JUMPER

W56

w12

W32

wb4

FULL-DUPLEX ACTIVE

FULL-DUPLEX

PASSIVE

PASSIVE RECEIVE/

W2 W5 W3 W32 WO W8 W6 W7

AN VL
N N

W10

Pd /

AAAAAAAAA/-

(PINS 4TO13)

—

ACTIVE TRANSMIT

ACTIVE RECEIVE/

W54

M7722 CURRENT LOOP CONFIGURATION JUMPERS

Jea

PASSIVE TRANSMIT

1 = JUMPER INSTALLED.

210
T30

e 10

5%’-- %)

2.0

—
©

@oooo

s
S

(10

A= A=A
A= A
AT A

Ao A

0
D00

LEGEND:

IS 05
0

EVEN PARITY

(NO PARITY)

UOUUVUUGYUUTe

8TH BIT MARKING

w10

WGVWVES

FUNCTION

M7722 PARITY CON*‘IGURATION JUMPERS

ESS

000000O0O

| 0

1 = JUMPER INSTALLED.
0 = JUMPER NOT INSTALLED.

I
0

LEGEND:

00O

LTJ

*CONNECT USER-MANUFACTURED CABLE BETWEEN J3-3 AND 56 AND OPERATING SYSTEM.

0
fmwwfl.

R70

220

—{— 3
—{—

HALF-DUPLEX

PASSIVE"

C86=

ACTIVE"®

fl.—

300400 -Ord-B-0r0

]

—{)-

HALF-DUPLEX

210
10

0 J0

330
30

(d0
0
b~
TM A = AW o = 4

20
0

W1 INSTALLED - STANDARD BELL VOLUME
W1 NOT INSTALLED - LOWER BELL VOLUME

M7722 BELL VOLUME

0 = JUMPER NOT INSTALLED.

CP-3142

Figure 2-10 Location of Jumpers
on M7722 Logic Board

2-10

JUMPER CONFIGURATIONS FOR M7723 LOGIC BOARD

FUNCTION

wWé

W13

W14

FULL-DUPLEX ACTIVE

FULL-DUPLEX PASSIVE

PASSIVE RECEIVE/

ACTIVE TRANSMIT

ACTIVE RECEIVE/
PASSIVE TRANSMIT
HALF-DUPLEX ACTIVE"*

HALF-DUPLEX PASSIVE"*

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

FUNCTION

W10

W11

W15

8TH BIT MARKING

8TH BIT SPACING

EVEN PARITY

ODD PARITY

w14

LEGEND
1 = JUMPER INSTALLED

0 = JUMPER NOT INSTALLED
X = DO NOT CARE

STANDARD BELL VOLUME

W1 NOT INSTALLED

LOWER BELL VOLUME

W12 NOT USED

NO FUNCTION

W10

W1 INSTALLED

W16

W11

8142-1

Figure 2-11
Location of Jumpers
on M7723 Logic Board

2-11

JUMPER CONFIGURATIONS FOR M7728 LOGIC BOARD
wi4

FUNCTION

w13 z

FULL-DUPLEX ACTIVE

FULL-DUPLEX PASSIVE

-0

-1

HALF-DUPLEX ACTIVE®

HALF-DUPLEX PASSIVE®

ACTIVE RECEIVE/

PASSIVE TRANSMIT

‘

PASSIVE RECEIVE/
ACTIVE TRANSMIT

;

*CONNECT USER-MANUFACTURED CABLE BETWEEN J3-3 AND 5 AND OPERATING SYSTEM.
w17

W10

w11

W15

8TH BIT MARKING

8TH BIT SPACING

FUNCTION

EVEN PARITY

ODD PARITY

w16

NG PARITY

LEGEND:

1 = JUMPER INSTALLED.

0 = JUMPER NOT INSTALLED.
X = DO NOT CARE.

FUNCTION
PRINT PARITY ERROR

w18

w19

W20

INDICATION

EIGHT BIT CONTROL OVER
OPTIONS

(NO PARITY DETECTION)
W1 INSTALLED

STANDARD BELL VOLUME

W1 NOT INSTALLED

LOWER BELL VOLUME

W12 INSERTED

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

W12 NOT INSTALLED

POSITION

ESTABLISHES

FDX/HDX SWITCH
WHETHER

TRANS-

MITTED CHARACTERS ARE PRINTED

W16 NOT USED

NO FUNCTION

W17 NOT USED

NO FUNCTION

W20

wi1

w19

W18 W10

Wis
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 LLA36 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 LA35 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 LA35 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 LA35 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 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.

STR.

ALY

CHARACTER
SET

PAPER

DEVICE

SELECT

OUT

SELECT

AVAW

7622-28

3.1.1 POWER ON/OFF Switch
The POWER ON/OFF switch connects and disconnects the line voltage to the LA36 DECwriter 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 LINE/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 FDX/HDX switch controls the printing of transmitted keyboard characters. When in the FDX
position, characters typed on the keyboard are transmitted; only received characters are printed. When
in the HDX 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 HDX mode.

3-1

POWER

OFF

e MODE s BAUD RATE =]
;— 150 ‘-‘

¥y

INE

FOX

116

300
HERE

37
HARA(TEQ %{?

PAPER

DEVI (E

ELE(

OUT

SELECT

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
110 and 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 selects 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 control 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

3.1.10

PAPER OUT Indicator

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.

When illuminated, the PAPER OUT indicator glves a visual indication that the LA36is out of paper.
Printing stops when the out-of-paper conditionis detected.

3-2

=TO
HARAL }'F %ET

PAFER
Uy

DEVI(E
t:ELE

setECT
AV AL

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 AVAIL 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

3.1.14

CAPS LOCK Key

The CTRL key provides the LA36 operator with a method of transmitting ASCII control codes
(0005-037;). 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 (000s-0375).

The 26 letter keys transmit only uppercase when the CAPS LOCK switch is down. None of the other
keys are affected.
3.1.15

SHIFT Key

This is a momentary switch which, when depressed, allows selection of uppercase for all printable
characters.

3.1.16

TAB Key

3.1.17

ESC (SEL) Key

The printer does not respond to TAB (code 0115) unless option LAXX-KY is installed.

‘The ESC (SEL) key generates code 033s. 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

POWER

OFF
—

BAUD RATE —]f

‘;- 150'~"

LINE
i
[

FDX
H{IY
e

308

7622-28

3.1.19 RETURN Key
The RETURN key generates code 015s. 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;5. 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 010s. 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 177;5. 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 LA 36 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.

BAUD

RATE

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
110

300
110 and 300

Character Rate
10 characters/second

30 characters/second

15 characters/second

3.2.3

PAPER OUT Indicator
The PAPER OUT indicator, when illuminated, gives a visual indication that the LA3S5
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 LA 35 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
paper to the head of the form.

3.2.6 Bell
The bell indicates that a bell code was received.

3-6

is to advance the

3.3

LA36/LA35 COMMON CONTROLS

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

CARRIAGE
ADJUSTMENT

LEVER

7666-16

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

3.3.3

Tractor Adjust Knob

The Tractor Adjust knob allows fine horizontal
adjustment 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.

3.4 LOADING PAPER AND NEW FORMS
The LA36/LA35 can accept multipart forms, with widths from 7.62 to 37.8 cm (3 to 14-7/8 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

Set the POWER switch to OFF.

Lift the cover.

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

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

7666-32

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

CARRIAGE
ADJUSTMENT
LEVER

3-10

7666-16

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

Close the left tractor cover.

7666-33

Loosen the Tractor Adjustment knob on
the right tractor about 1/2 turn.
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).

7666-35

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 3.5). An indication of
a worn ribbon is that the first copy in a multipart copy is poor but the remaining copies
are good.

7666-3

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.
1.

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.

e ACTOR AD N MENT KNOBS
7oe610

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
For fine vertical positioning, press in and turn
the Paper Advance knob.

PUSH
IN HERE
AND TURN TO

ADJUST PAPER
VERTICALLY

PAPER

ADVANCE

KNOB

7595-4

3-13

3.4.5

Reloading Paper

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 unthreading 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.

Set the POWER switch to OFF and lift the
cover.

Record the setting of the Carriage Adjustment lever. Move the Carriage Adjustment
lever to the highest number.

Remove the ribbon spools and ribbon.
Save one spool to be used with the new

ribbon.

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

7666-17

Wind 10 turns of ribbon on the empty
spool.

RIVET
7666-21

7622-22

CARRIAGE LEVER ADJUSTMENT

RIVET
CP-2006

Place the full spool on the left spindle and turn clockwise until it drops into position.

Guide the ribbon around idler spool A through guide B, and around the outside of idler spools C
through E.

Guide around the front of head F and idler spools G through I.

Guide the ribbon through slot J (direction changing guide) and around idler spool K.
10.

Turn the spool clockwise until it drops into position.

11.

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

Interface Description

NOTE
The LA3S5 and LA36 have identical interfaces.

However, the LA3S5 utilizes only the receive
circuitry.

3.6.2 Interface Specifications
The interface specifications for the DECwriter
serial 20 mA current loop are shown below.

I- (|[

lo
[*

20mA

o
*|

START _ sg
e

——

PARITY

BITS

]

DATA msg

BIT [

S U

B i

) STOP

'T T T T T -rfr|

>»150 BAUD

BIT

l’- 6.66ms
|
.

33.3 ms

|+
|

]

.
START _sg

BITS

‘l

r-rr7vrTrTr—TTM

[ IR I

PARITY

MsB

DATA

BITJ—

20V
2.0mA

4 4

40V

| I

Marking current

[

Max.

0.5v
0.4mA

N R

66.6ms

Voltage drop, marking
Spacing current

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

50V

> 110 BAUD

|-9.09ms

-—|

-0|

Min.

R I

| I

Transmitter (LA36 only)

]

!
:
2 :
PARITY
8
X
|
STOP
DATA MSB
START ~LSB
BIT J—
ITS
]
BITS
M.
- T T TLI T
)T TT T
B
ma—

There are three interface option kits available
for the DECwriters: LAXX-LH, 20 mA Cable
Option Kit; LAXX-LK, 20 mA Cable Option
Kit (DEC10); LAXX-LG, EIA Interface Option
Kit. Refer to Chapter 2 of this manual for installation instructions for these interfaces.

Open circuit voltage
(of circuit being driven)

|
g

1{00Oms

[

>300 BAUD

STOP

BIT

|<—3.33ms
cP- 1177

80 mA

Serial Interface Timing Diagram

Receiver

Passive, isolated

Voltage drop, marking
Spacing current
Marking current

Min.

Max.

1.2V
0.0mA
15mA

2.7V
3.0mA
80mA

Receiver /Transmitter (LA36 only)

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.

4.7V
1.7V
0.0mA 3.0mA
1SmA 80mA

3.7

PROGRAMMER’S GUIDE

3.7.1 LA36 Programmer’s Information
|

r—

NOTE

All information in this paragraph is applicable to

the LA35, with the exception of keyboard operations (Paragraph 3.7.3). This is due to the fact

that the LA36 and LA3S receive operations and

surrer | |recever| |

IEAING

| " —————=—=—=—=—==—==—<
afentenbat ettt H

baud rates are identical.

3.7.2 Transmitting Characters and Commands

| XKEYBOARD

TRANSMITTER

LAS6

by typing keys on the keyboard. The 7-bit ASCII
equivalent of each key is transmitted the instant
a key is depressed.

OUTGOING
DATA

L ___________ -

The only way an operator can transmit data is

3.7.3

PRI

cP-1ee

Special Command Keys

3.7.3.1 CTRL 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 0. For example, the ASCII code for the letter ““g” is 147
(1100111).
Bits 6 and 7
Holding down the CTRL key and typing the “G” key transmit the ASCII Wl 11).

Bits 6 and 7 are forced to 0
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 nonprinting, 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

KEYBOARD OPERATIONS

RECEIVE OPERATIONS

To Transmit, Type Key(s) (LA36)
Character

ASCII Code | Character

000

NUL

002

STX

001

003
004

SOH

SHIFT*

ETX
EOT

CTRL* | CHAR

SPACE

vV
Vi
v

C
D

005

ENQ

006
007
010
011
012

ACK
BEL
BS
HT
LF

Vv
v
v
vV
vV

F
BELL
H
I
J

014
015
016
017
020

FF
CR
SO
SI
DLE

N/
v
vV
vV
v

FF
M
N
o)
P

021
022
023
024
025
026
027
030
031
032
033
034
035
036
037
040

DC1
DC2
DC3
DC4
NAK
SYN
ETB
CAN
EM
SUB
ESC
FS
GS
RS
US
SP

Vi
N
Vi
Vv
vV
v
N
v
vV
Vv

Q
R
S
T
U
Y
W

v
Vv
vV
Vi
Vv

[
\
=
~
—
space bar

013

VvV

vV
vV

Printed

Action/Description

None

—
None
_
Sound Alarm Bell
Backspace one position
None
Advance Paper one line

None

None
Move print head to left margin
None
.

X
Y
Z

None
None
Blank Spacd | 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) (LLA36)
Character
Character

041
042

”

043
044

045

046

CTRL*

CHAR

Printed

Action/Description
Print character, move print head

[ X4

one position to the right.

R L L L I

047

SHIFT*

S L LN L L L

ASCII Code

050
051

052
053

074
075

076
077
100
101

102

103
104

)
O
W~
N
N
O] 00}
1

=
L] AW

073

wi (o] £+-1 I g NON hnd AV

072

071

070

<LK

067

066

wh [@] I=-1 Id ROY Ind A/

065

1Ol 0ol QN

064

063

Ol 0o

062

061

060

oio|w|
> ®||V

057

056

=] OTM

055

Ol T

054

Print character, move print head

3-21

Table 3-1

ASCII Codes and Responses (Cont)

KEYBOARD OPERATIONS

RECEIVE OPERATIONS

To Transmit, Type Key(s) (LA36)

116
117
120
121

122

123
124
125

126
127

130
131

132

133

134
135

136

N|=<]|¥%]| €| <|c]H|»|m|O]|7|O|Z]|Z|C|R|—|T|T|@Q|Tm@m

115

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

> =

114

Printed

=m|o|m|o|zZz|Z| IR

113

CHAR

112

CTRL*

Sl—l-l—| Nl =< x| gl <l

111

S LN L LN L L R L L L R L L L A LS LS A A LS AU SR

110

107

N|=<[X}=| <[]]|»|m|O]|V|O|Z|Z|T|AR|=|T|Zm|@Q|TM|
TM

106

S>I—=| |

105

CEEEEE——

SHIFT*

|~ |z=|O|T]| m

Character

ASCII Code | Character

145

146
147

150

oo
e
o

144

143

T QMmO
O @& >

142

jo ja]j]o]
o

141

=l |

140

137

Print character, move print head

3-22

Table 3-1

ASCII Codes and Responses (Cont)
RECEIVE OPERATIONS

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

Character

161
162

163
164

165

166
167

170
171

172

173
174
175

176

one position to the right.

Z| X

[

w Cad o

T
R

Action/Description
Print character, move print head

U=l ~In]|<| x| |<]|e]|~]|]|"|e|=]|o|=]|B

160

B O] | O

157

=l < a3 v

[E—

155

Printed

CHAR

N <

w Qomd o

154

156

CTRL*

LIl

153

Y=l ~|nl<|x]s]l<]le]|~]|=|"|ol=|o|=]|2

152

SHIFT*

<4<

151

Character
bo

ASCII Code

Print character, move print head

one position to the right.
177

DEL

DELETE

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.

PN
R LN =

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

Load paper (described in Paragraph 3.4).
Set LINE/LOC switch to LOC.
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/LOC switch to LINE.

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

3-23

3.9 USING THE LA3S
Using the LA35 requires almost no operator intervention. The following steps are all that may be
required to place the LA35 on-line.
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

e AC power cord is not plugged into wall outlet — plug it in.

e Current is not coming from wall outlet - check outlet with a
known working electrical device (such as a lamp).

e Check ac line fuse (following page).

e If none of the above, contact your local Field Service Office.
Print head does not print
characters.

e Check servo fuse - might be blown (following page).

e Print head may be set too far from paper - adjust the Carriage Adjustment lever.

e Check option interconnect cable (Chapter 2).

Light print

e Print head may be set too far from paper - adjust the Car-

riage Adjustment lever per impression adjustment procedure

(Paragraph 3.4.2).

e Ribbon ink has run out - replace ribbon.

e Reverse ribbon after 8-12 hours
of continuous printing. Ribbon should be reversed only once, then changed.

Paper does not advance

e Improper loading of paper - check tractor covers to ensure
that they are closed.

e Holes in paper are torn — turn DECwriter OFF and reload
paper properly.

e Paper snagged or caught by box.

3-24

Table 3-2

Operator’s Troubleshooting Guide (Cont)

Symptom

Possible Cause and Corrective Action

Paper tearing on multipart forms

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

Line bunching

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

F2 FUSE RATING

FUSE
2A 5B

FUSE RATING

% VOLTAGE

FUSE

!
H

AN AN

A BN

AC LINE FUSE

FUSE RATING
115V.

3A SB

230V.

15A SB

SERVO FUSE

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, DEC1 (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.
DECI

logic function

SET HDE

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 cm/sec (6 in/sec) for catch-up mode, 127
cm/sec (50 in/sec) for carriage return, slower speeds for carriage return slowdown, and 0 in/sec for
idle.
|

OVERALL FLOW

START

)

AR=0000 @ POWER UP

POSIT

ENTERS
AFTER

208 CLK
SYNC

SERVO

SPEED

INPUT

PRINT EXIT
WHILE SYNC
ON INC.

PRINT
!

BELL

\COUNT/

\/
PRINT

)

]

COUNT
LCV

CP-1379

Figure 4-1

Microprogram Flow Diagram

4-2

The INPUT routine operates the character buffer address register as a first-in /first-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 of the 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 1 to preserve the proper state of the LSB which is (1) for PRINT
and (0) for LINE FEED.
Locations 0, 1, 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 11 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

POS LO

POS MD

Usage
12-Bit Carriage Position
(Relative to column)

POS HI

COL LO

8-Bit Column Count
(Records columns printed)

COL HI

RD ADR

Character Buffer Read Address

LCV 1

LCV Timer

WT ADR

Character Buffer Write Address

LCV 1

To Keep WT ADR=RD ADR

WD CNT

Character Buffer Character Count

6
7
10

Unused

COUNT

Print Dot Count, LF Pulse Count

LSB=1 for Print

LCV 2

LCV Timer

LF |

Line Feed Timer

PT 1

Print Timer

INIT 1

Init Timer

POS ER

Position Error

LF 2

Line Feed Timer

PT 2

Print Timer

INIT 2

Init Timer

LCV ST

LCV Status

LCV 3

LCV Timer

BELL 1

Bell Timer

BELL 2

Bell Timer

BELL ST

Bell Count (Status)

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 1, the position count in locations 0, 1, 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 LCYV status is required only
when WD CNT = 0, it must be preloaded to a value (125), 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
LCYV). 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 (INIT) 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.

POWER UP

’

START

TIME OUT
ROUTINE

INIT

CLR BELL

SET LF HOLD
SPEED = -6 IPS

L INIT 2: = 1100, ]

CLRINC

TIME OUT

416 MSEC

i
TIME OUT

ROUTINE fi

COoLLO:=0

1 PASS EVERY

COLHI:=0
RD ADR: =0;

416 uS

WT ADR: =0

WD CNT: =0

CNT: =0;

LCVST: =0
BEL2: =0;
BELST: =0

[

(INIT 1:=INIT +1J

‘

POS Hi: = -1

POS MD: = -1
POSLO: =-5

LOAD INC
CNTR/CLR
INIT

(POS = -5)

I NAV

[NIT 2:=INIT 2 +1

:
r

2
INIT

TIME OUT
ROUTINE

CP-1624

COMPLETED

——

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 us 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;a
nd all processing of carriage position is done by the POSIT routine, whether the printer is doing
carriage return, printing, or just correcting position randomly.

4-8

POSIT

POS: = POS +1

'FLOW THROUGH

(FOR POSIT)

START

HERE GENERALLY

POS: = POS -1

(FOR POSIT)

START

‘

EVERY 416 uS.

208

=0
POS LO: =

‘

POS LO +1

-0
POS LO

£0

TO SERVO

POS ER: =

POS ER -1

POS ER +1

CLR BELL

PO$ MOD: =

PO$
MD +1

POS MD

‘

m
=1

POS LO

POS MD

-0

POS Hi: =
POS HI -1

=0
POS: = POS +1

POS: = POS -1

POS HI: =
POB HI +1

COUNT

POS MD: =

POS MD -1

‘

LINE FEED NOT

LINE FEED
IN PROCESS

IN PROCESS

DONE

SET LF HOLD

TO SERVO

)
POSLO: =
POS LO -1

CP-1625

CP-1626

POSIT Routine

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.

CLRC/B

)

TOPO

=0 ‘
BORROW

’- - —EIGURE 4-3

CLRC/B

)

TO SPEED

TO P1

- -[FIGURE 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.

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 print-

er 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 char-

acters 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.

4-10

Figure 4-4

SERVO Routine

Table 4-2

SPEED Algorithm

Count=0 |WD
Printing
CNT|

=()

Position|

Speed (in/sec)
+ =Print
-= Return Motion

216
>8
>4
>2
=]

-50
-30
=20
-10
-6

=()

0
+3
+6

=()

(POS LO—-POS MD—
POS HI VERSION)

SPEED

(ACTUAL IMPLEMENTATION)

\Posm/
POS HI

>16

POS MD

<16

WD CNT

SPEED: = +3 IPS

SPEED = +6 IPS ]
.

SPEED: = -50 IPS |
TO INPUT

I SPEED: = -30 IPS

'SPEED: = -20 IPS

SPEED: = -10 IPS

|
POS LO

SPEED: = -6 IPS

COUNT

TO INPUT

—

I SPEED: =0 IPS

TO s1

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 UART
data available (DA) and, if cleared (no charac-

INPUT

ter), 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
UART as the 16th memory location, and pro-

ceeds immediately to service the bell.

UART D2

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.

If WD CNT is not equal to 15, word count is

incremented, write address is incremented, the

—

L WO CNT: =

character is put into the buffer at the new write

address, and UART DA is cleared as the pro-

gram proceeds to the BELL routine.

WT ADR: =
WT ADR +1

CBA: =

WT ADR

cB(cBA]: =
UART OUTPUT

CLR UART DA
CBA: = RD ADR

CP-1629

Figure 4-6

4-12

INPUT Routine

#16

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
LCV.
BELL

BELL ST

SET BELL

CLR BELL 1

1: =
BELL

BELL 1+ 1

BELL 1

BELL 2: =

BELL2 +1

BELL ST: =

BELL ST -1

TO NEXT

TO LCV

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 off).
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 us 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 O 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 us head drive enable (HDE).

NOTE

At all other times through this routine, operation is
synchronized on the 416 us 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 us HDE is then timed out in PT1 and PT2 locations of the control RAM on the 1.184 us
instruction timing cycle of the microprogram. During this time, the character is printed. At the end of
that time, HDE is cleared, print is reset to 1, count is set once again to -1, and the program reenters the
POSIT routine.

4-14

POS LO

SET HDE

PT1: =
PT1+1

POS MD

600 uS TIMED ON
THE 1.184 uS
INSTRUCTION

CYCLE TIME OF
THE MICRO-

\Posm/'o

POS +#0
<7

>17

PT2+1
POS=0

COUNT

~_
COUNT: =0
TO POSIT

PROGRAM.

=
PT2:

PT 1: = 0000

POS ER: = -1

PT 2: = 1010

COUNT: =7

CLR INC

‘
={)

INC

TO POSIT

CLR HDE

PRINT: =1

‘

COUNT: =
COUNT -1

:
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 LF1 and LF2. On the trailing edge of the 208 us 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 LF1 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 0. 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

\COUNT/

LF2:=LF2+1

£0

LF2

EVEN

COUNT

(

TO POSIT

)

COUNT: =

COUNT -1

3.7 msec

8.2 msec

COUNT: =

COUNT: = 2

COUNT: =1
DONE

PULSE LF

( TO POSIT )

oDD

COUNT: =0

-0

7.5 msec

LF1:=1100

L LF 1: = 0000 ]

LF 1: = 1110

LF2:=1101

LF2: =111

LF2: = 1101

]

| G

LF 1: = 0000

LF2: = 1110
-

( TO LFP2 )
=1

’
PULSE LF

208

( TO LFP2

CLK

208

( TO POSIT )

CLK

I SETLFHOLD

( TOPOSIT

)
CP-1632

Figure 4-9 LINE FEED Routine

4-17

4.1.10 LCYV 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

Lev

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.

Lev 1:=
mad

LoV 1

LtCv
2: =

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

LCV
2 +1

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 LCYV status occurs
if a printable character is received during LCV

timeout.

v
(Lev sm

LCV 3

(Levsm

POS ER: = -4

CP-1633

Figure 4-10

LCYV 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

WD CNT: =
WD CNT -1

COL HI

RD ADR:
=

RD ADR +1

(8 X 16 + 4 = 132)
IGNORE CHAR

coLLQO

l CBA: = RD ADR

\/C

TO POSIT

AFTER COL 132

’

I LCV ST: =0100

‘

COLLO: =

TO LF

COLLO+1

( TO POSIT )
+0

Qro N )

( TO POSIT

CcOL LO

coL Hl:#

)

COL HI +!

BEL ST: =
+4

‘

BEL ST +2

TO POSIT

‘

TO POSIT

(

TO POSIT

)

CP-1634

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

4-19

«
r

]

#1 (5 uS)

COUNT: =9
1

I
.

LO: =
COL
coL Lo -1
_

LF 1: = 1000 1

F)
, CLOLO:
=
CcOL LO -1

POS ER: = + 1

-0
,

TO POSIT

COL HI -1

]

( TO LFP1 )— - -{[FIGURE 4.9]

=0
COL HI

COL HI: =

[ LF2:l= 1110 ]

.
=
HI:
COL
COL HI -1 J

POS LO:+=1
POSLO
POS LO

coL i

CcoL LO

C TO POSIT )

POSMD +1

POSMD: =

=
POS HI:

POS HI + 1

‘

‘;‘ro POSIT

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
us 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 24. 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 us 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 pus.

The sequential instruction flip-flop may be interrupted by instructions of the classes referred to as
JUMPI, JUMP2, JUMP3, CLR, SKIPI1, 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 any one of thirty-two 16-word pages of the microprogram.

The JUMP?2 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

CLOCK

DEC 1

SKIP 1

Jsmm

| 5

SKIP

— 228

SKIP 1—

SKIP 2—»

==
INSTRUCTION 585§

JUMP 11—

SELECTOR

ADDRESS

JUMP 2 ONTROL

JUMP 3 —of

CLR—»

PROGRAM

[wogl|

—

CONTROL

— o Fa

512X8

ADDRESS

» »

5
DECE2

523

— o -

ROM

E
& — Mux

»
’é

MUX

—

BRING 41
BRING
1

4 BIT

BRING 4

GATE

zero

DETECTOR

[TRECTO

RE4GI%"|TER
(REQ)

BITO
BIT
1

STORE

BIT2

BIT3
CLRCAasB

SET BELL

NIT

BELL

CLR BELL—* <ySTEM

STEP LF

LOAD DAC

CLR HDE ) l

2.4 KHz—

SET LF Hou)—l

CARRY (C)

LINE FEED
STEPPER

KEYBOARD

SYSTEM

SEFC;CSRSl‘Y\giEM

BORROW(B)
INC

LOAD C.B.
ADDRESS
KEY

R
STROBE

CHARACTER
BUFFER

ADDRESS

SET

CLR

HDE

WRITE

BUFFER

SERIAL

S&*ys#

1024 X 8

UNIVERSAL

COMMUNICATION
INTERFACE

EOC

CHARACTER

RECEIVER

16 X 8

TRANSMITTER
(UART)

PRINT HEAD

ROM

CHARACTER
BUFFER
RAM

UART DATA
AVAILABLE (D.A.)

CLR UART D.A.

Cfig::g%R

cL R KBD HOLD —l
KBD HOLD

F.F.

DECODER
v

KBD HOLD

PNTABL

LF BS BELL
cP-1877

Figure 4-12

Control Logic Block Diagram

The JUMP3 instruction is similar to the JUMP2 instruction with the additiona
l 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 SKIP1 and SKIP2 instructions are conditional skip instructions. The conditions are the inputs to
MUXI1 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, BRING1, STOREI, and
DECI.

The BRING#4 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 BRINGI1 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 DECI1 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 1 to REG), -1 REG (subtracts 1 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 unshifted 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 us) 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 2 l

BIT 1

BIT 3

BIT 4

CONTROL

CTRL
KEY

__BIT S
BIT 7

X0/YO

X1/

X2/Y2

X3/Y3

X5/Y5

X7/Y7

:—‘—,,77

64/128

DELAY

X8/Y8

ROM

DATA READY

PAD

PULSE | STROBE

SHAPER [ (KEY

—

NUMERIC {Xx6
Lko3

6
MPC

—

X6/Y6
X0

KEY 1-

j}_

STB H) J

CLOCK

+5
l

BREAK | BREAK + L GATE MPC5

STROBE

SHIFT

KEY

LOCKOUT
REPEAT

KEY

CP-1578

Figure 4-13

LKO02/LKO03 Keyboard Logic Diagram

Table 4-3

Keyboard ROM Addressing

ASCII Code

Octal

ROM Addressing
Y Line
X Line

Key

b7-bl

Code

Esc
2
r
h
[

0011011
0110010
1110010
1101000
1011011

33
62
162
150
133

8
7
5
3
2

9
8
6
4
3

75
61
145

0
7
5

l
9
7

=
1
C

0101100
0111101
0110001
1100101

4-25

Table 4-3

Keyboard ROM Addressing (Cont)

ASCII Code
b7-bl

Octal
Code

1100111

147

1101101

155

0110000

1110111

167

1100110

146

1101110

156

Key

ROM Addressing
X Line
Y Line

0101101

0111001

1110001

161

1100100

144

1100010

142

0001000

0111000

1110000

160

1110011

163

1110110

166

0110111

1101111
1100001

|
9

143

5
3

110001 1

157
141

0100000

0110110

40
66

8
7

S
4

1101001

151

{

1111011

173

:
X
5
u
CR
|

0111011
1111000
0110101
1110101
0001101
1101100

73
170
65
165
15
154

3
1
7
5
4
3

0
8
5
3
2
1

LF
Z
4
y

0001010
1111010

12
172
64
171

2
|

0
9

7
5

’
k

47
153

\
/

0100111
1101011
1011100
0101111

134
57

4
3
2
l

6
4
3
2

HT
3
t
j

0001001
0110011
1110100
1101010

11
63
164
152

8
7
5
3

0101110

DEL

0110100
1111001

1111111

177

140

1100000
4-26

2
1

1
0

8
7
S
3

2
1

Table 4-3

Key

Keyboard ROM Addressing (Cont)

ASCII Code

b7-bl

Octal

Code

ROM Addressing

X Line

Y Line

ESC

0011011

1000000

100

1010010

122

1001000

110

]

1011101

165

0111100

0101011

0100001

1000101

105

1000111

107

1001101

115

)

0101001

1010111

127

1000110

106

1001110

116

—

1011111

137

(

0101000

1010001

121

1000100

104

1000010

102

0001000

0101010

1010000

120

1010011
1010110

123

\Y%

126

3
1

8
6

0100110

1001111

117

1000001

101

1000011

103

]

0100000

1011110

136

1001001

111

}

1111101

175

;

0111010

1011000

130

0100101

1010101

125

0001101

1001100

114

]

0001010

1011010

132

4-27

Table 4-3

Key

Keyboard ROM Addressing (Cont)

ASCII Code
b7-b1

Octal
Code

ROM AddressinL
Line
Y Line

0100100

1011001

131

0100010

1001011

113

1111100

174

O111111

]

0001001

0100011

1010100

124

1001010

112

DEL

1111111

177

O111110

1111110

176

CONTROL MODE
ESC

0011011

DC2

0010010

DC2

0010010

0001000

ESC

0011011

0001100

]

0011101

DCI

0010001

ENQ

0000101

BEL

0000111

0001101

DLE

0010C00

ETB

0010111

ACK

0000110

0001110

0001101

0011001

DCl1

0010001

EOT

0000100

STX
BS

0000010
0001000

2
10

]
0

CAN

0011000

DLE

0010000

DC3

0010011

SYN

0010110

]

ETB

0010111

SI
SOH

0001111
0000001

17
]

5
3

1
9

4-28

Table 4-3

Key

Keyboard ROM Addressing (Cont)

ASCII Code

Octal

b7-b1

Code

ROM Addressing

|XLine

Y Line

ETX

0000011

NUL

0000000

SYN

0010110

0001001

ESC

0011011

ESC

0011011

CAN

0011000

NAK

0010101

NAK

0010101

0001101

0001100

0001010

SUB

0011010

DC4

0010100

0011001

BEL

0000111

0001011

0011100

]

0001111

0001001

DC3

0010011

DC4

0010100

0001010

DEL

1111111

177

0001110

NUL

0000000

SHIFT AND CONTROL MODE
ESC

0011011

NUL

0000000

DC2

0010010

0001000

0011101

0011100

0001011

SOH

0000001

]

ENQ

0000101

BEL

0000111

0001101

0001001

ETB

0010111

ACK

0000110

4-29

Table 4-3

Key

Keyboard ROM Addressing (Cont)

ASCII Code
b7-bl

Octal
Code

ROM Addressing

X Line

Y Line

0001110

0011111

0001000

DCl1

0010001

EOT

0000100

STX

0000010

0001000

0001010

DLE

0010000

DC3

0010011

SYN

0010110

ACK

0000110

0001111

SOH

0000001

ETX

0000011

NUL

0000000

0011110

0001001

[

0011101

SUB

0011010

CAN

0011000

ENQ

0000101

NAK

0010101

0001101

0001100

0001010

SUB
EOT

0011010

12
32

2
l

0)
9

0000100

0011001

STX
VT
FS

0000010

31
2

5
4

4
3

3
2
1
8

2
1
0
8

7
5
3
2
1
0

7
5
3

US
HT
ETX
DC4
LF
DEL
RS
RS

0001011
0011100
0011111
0001001
0000011
0010100
0001010

1111111
0011110
0011110

37
11
3
24
12
177
36
36

4-30

2
1
0

Table 4-4

Numeric Keypad ROM Addressing

Key

ASCII Code
b7-b1

Octal
Code

ROM Addressin
X Line
Y Line

1
2
3
4

0110001
0110010
0110011
0110100

61
62
63
64

6
6
6
4

4
5
6
4

5
6
7

0110101
0110110
0110111

65
66
67

4
4
2

5
6
4

8
9
0

0111000
0111001
0110000

70
71
60

2
2
0

5
6
5

0101110

0101100

0101101

ENTER

0001101

XD-X8

| | o.
)

YO-Y8

STROBE

DELAY

DATA

READY

A
|

—g~

STROBE

DATA (BIT t- BIT 7)

CP-1615

Figure 4-14

Keyboard Timing Diagram

4-31

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

LINE

PRINTER

-—

|¥— o1

< j/ OR g

-—

20MA
LOOP

RCVR

LOCAL =

CONNECTS

TO STANDARD

| —

) CURRENT

LOOP

INTERFACE

LINE

—_—

20MA
LOOP

DRVR

KEYBOARD _./—’| LoCAL
B ———

| LOGICAL
|
ACTION OF |
LINE/ LOCAL

LSWITCH

LOGIC
BOARD
CONNECTORS

Ja
"

<«— RCV

CONNECTS

TO OPTIONAL

—® XMIT

INTERFACE
CP-1163

Figure 4-15
}:

66.6 ms

;{
I

|
|

)

aurl'

ol 1

PARITY;

DATA

msB

|
|

>150 BAUD

BIT

N TN S

E—

-OI
33.3 ' ms

|
|

WS S

9.09ms

pPamiTY

BITS

>300 BAUD

BIT

TTTTTTT
]

DATA pep. ' | STOP

BIT

START _|sz
—T

BITS

]

|e-3.33ms
cpP-117?

Figure 4-16

Data Communications Interface Timing Diagram

4-32

STOP

>110 BAUD

T T TT T T Ti
T
1
'
SN SN VS

|<-6.66ms

PARITY;

MSB

[Illl'll'l|
[

|
P

DATA

BITJ:

START~LSB

T
T T T T

STOP

IT||ITI:
I

100 ms

|
|

START _ | sg

—

Data Communications Interface Diagram

4.5.1 20 mA Loop Receiver
A simplified diagram of the loop receiver is shown in Figure 4-17. Signal line current can be up to 80
mA. 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.

PHOTO

ISOLATOR

TRANSMIT

BREAK/LINE/ g0
LOCAL GATES
——&

MPC5

-—

|
CP-1579

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 mA. Voltages exceeding 40 V should not be used to drive the loop.

+5V

’

PHOTO

ISOLATOR

S.I.

BREAK/LINE /LOCAL
GATES

A A A4

A
A A

LA
A 4

MPC5

A
A A

RECEIVE

cpP-1580

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.
592ns

%+5V

CLK
L
1.184ms

CLKO

1.6896 MHz

RIPPLE

CLKO

rippLE R

COUNTER | ..

cLock

CLK1

COUNTER

r3j}=18

CLK1

RO}=2

=15

BINARY

|=4

COUNTER

CLK

R3 l—T

MSB

176 KHz

208H
76};5

19L

MSB

CLK

4.8KHz

=1
BINARY
COUNTER

I*——ZOBps —'.l
CP-15861

Figure 4-19

592

Clock Logic

[

1.184 us

I
l

1.184,s
CP-1616

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 us

844 kHz (CLK)

50 ns pulse/1.184 us time period

106 kHz

9.4 us

53 kHz

18.8 us

26.5 kHz

37.7 us

13.25 kHz

75.5 us

4.8 kHz

208.3 us

2.4 kHz

416.7 us

1.7 kHz

588.2 us

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

[ WRITE BUFF

DEC1 MPC4 ¢

KEYT?

|CLRR

pONE |-RAH :g’c‘;

R DONE

|0y

DATA

S.0. COMMUNICATIONS

XD5

INTERFACE
MPC5

KEY4 |04

T’

KEY 3

KEYBOARD

UART

XD3

X DI

KEY STBH |\nyp

RD2 [—

RD3 |—

x:gg UP W.U.L

DATA COMMUNICATIONS

INTERFACE MPC5

s.I.

2o |

S.1.

RD7

[MPC6

}—

co8 b |

LINE/LOCAL

CLKS

\endls

r 1.7T6KHz

RD4 —— | cB RAM

RDS [—

2SB

+5V

—\

—
CLOCK LOGICfi 2.4KHz2
MPC5

| 4.8KHz

TM\

DD
—

-O

(‘rv

|
BAUD RATE

}
+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 UART.

Table 4-6

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.

Baud Rate Switch Connections

Function

J2-v

J2-T

150 Baud

300 Baud

110 Baud

4.8 CHARACTER BUFFER/GENERATOR AND PRINT HEAD SYSTEM
A simplified diagram of this logic is shown in Figure 4-22. Characters from the UART are stored in the
character buffer RAM (CB RAM). This is a 15-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 DECI.
-

SET HDE

DEC 1

__l
CLR

HDE

HD EN
o

MPC8

——

M2 p—— A6

UART
CHARACTER
MPCce| 103
—
BUFFER M3 p—
A7
RAM

— 1o

Mo p——— A 8

|HS1_MPC6

HS2

53|

HS3 MPCE

MPC6

M1 p——ao

M2 D————— CSO
B4 P
MPC6
CHARACTER
GENERATOR
ROM

REG | —
MPC4
|

V REF

VREF

M1 o——
a5

BUF HDE EN H

__I

ENB

—— o1

——{oo

-21v
REGULATOR

L WRITE BUFF

CHARACTER
BUFFER
ADDRESS
REGISTER

|33

HS6

e | MPC6
HS6
g7 |MPCE
PTBL

—

+21V

SOL
1

'—i 2]
>

N
__fsote
——-L;
Ne

|soL3

| 2
j\

SOL 4

—-LLN

IsoLs

|soLe

| 2
N

|soL7

n—

5 | MPCE

PNTABL H

MUX
1

MPC
4
MPC4

COL INC COUNT O

CONTROL

SOUNYER | cOL INC COUNT 1
MPC7
COL INC COUNT 2

P LF

CHARACTER | oo
DECODER
BEL

pMUX 2
HT
cP-1583

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
character buffer by LD CBA from DECI1. Each
time a character is written or read, the corre

)

!
2

°
o

ROM), which is a 1024 X 8 ROM that storesa

dot matrix pattern in a cell for every printable

sponding address is incremented by the MPC.

ROWS

As each character is read from the buffer, it is

(A [‘;;:?],*ggg’e,fi 5

decoded by the character generator ROM (CG

character and a unique code for each non-print-

able control character. Each character cell is

defined by a 7 X 7 dot matrix as shown in Figure

4-23. Rows are selected by the ASCII code,

A(4:9) and CS0. Subcolumns are selected by the

clnltlalelcln

SUB COLUMNS

(COLA,,[,L' 3cou~T)

COLumn INCrement COUNT, A(1:3). The dot
matrix is output to the solenoid amplifiers. The
first bit location in each row (subcolumn 0) con-

*
o

s,
cp-1892

tains all Os. All bits in the eighth row are used to

Figure 4-23 CG ROM Character Cell

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 (HS1 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.

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 MUXI1 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
T
‘[‘
T

CARRY—l

I——CARRY'

|‘__ CHARACTER BOUNDARY
®

°®

o
o

:___
5|

*
)

(SOLENOIDS) §

ROWS

(01" HEAD MOTION)

6 |

—d

°
¢

7 |

Jl
:

—1

|
-

—

~—

COL INC COUNT

(HEAD POSITION)

| HEAD TRAVEL >

CHARACTER

)

SPACING

CP-1593

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 ensures 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 MUX?2 and processed by the MPC.

4-39

49 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.

REG OH

—
SPEED
DATA

POWER

REG 1H

—_—

REG 2H

REG
MPC4

SPEED

SUMMING

NETWORK

CARRIAGE

SERVO

MOTOR

REG 3H

—

ENCODER

LOAD
DEC 1 D/A L
MPC4
WAKE UP

PTI

PT2

W, U.L

MPC
8

-INC
-TACH

CLOCK
LOGIC
MPC5

76usec
+INC

+ TACH

MUX 1 SH
MPC4

CARRY/BORROW

Mux2
BH

GENERATOR

MPC4

COLUMN
INCREMENT
COUNTER

DEC1CLRC/B

]

o |i e

H|
X
2 INC
MU

INCREMENT

MPC4

HOLD F/F

COL INC COUNT
TO CG ROM
MPC6

MPC4

DEC1 CLK HDEL |
¢4

LOGIC
MPC5

REV

THRESHOLD

T ]| oeTECTOR |
AND
FILTER

ENCODER
SIGNAL

DETECTOR

REV
COUNT

PT2

THRESHOLD

DETECTOR
AND
FILTER

1.184,.

CLK H

| cP-1584

Figure 4-25

Carriage Servo System

4-40

The encoder on the motor shaft generates two feedback signals: PT1 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 us timing signal
from the clock logic. The +TACH and -TACH produce 76 us 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 HDE 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

REG3

REG2

REGI

REGO

Nominal

(1)

Speed (in/sec)

0
0
0
0
0
0
0
0
1
1
1
1
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
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1

+6
+3
0
-3.8
-7.6
-11.4
-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 f{lip-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 us later, depending on the occurrence of the data with relation to the
clock signal.

The second positive transition of the 76 us clock signal clears the TACH flip-flops, thus providing a 76
us 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.

[ PTY

WINDOW

[

DIR

HOLD
E/F

F/F

—{c
|

THRESHOLD

TACH

232K

DETECTOR ¢

04TUF
v

TACH

SUMMING

MPC7

NETWORK
|

PT2

F/F

| cLock

TACH

SUM

TACH
Hc

L
CLOCK

76 pusec

LOGIC

MPCS.
SPEED
DATA REG{

MPC 4

rec oH

REG 1H
pcc

SPEED

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 (LEDs) 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, PT1 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,
PT1 leads PT2 by 90 degrees. PT1 and PT2 are applied to two threshold detectors. PT1 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

PT2

| \/

PT1

/!
0

/\ CLOCK

\_/

(

/\ WINDOW

90°

FWD-PT!

LEADS PT2

REV-PT2 LEADS PT1

—

DISK

+5V

MASK

SCHMIDT | PT2
PT1

TRIGGER | ENCODER

SIGNAL
DETECTOR

Meer

90°

BY 90°

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 PT1 as a
window and PT2 as a clock as shown in Figure 4-29. Encoder square wave PT1 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
T1, this flip-flop is clocked by the negative-going edge of the 1.184 us 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

<+—

PT1

WINDOW

REV

—

FROM

+ TACH

}TO + TACH

DIR
HOLD

—1C

FWO >
TO

THRESHOLD
DETECTOR
MPC7

—TACH

——«— FROM - TACH

PT
2
L CLOCK

COUNT

COL

INC

COUNT COUNTER AND

INC HOLD
MPCT

1.184 usecC

CLOCK LOGIC
MPCS

592 ns

CLK H
cP~-1586

Figure 4-28

Encoder Signal Detector

DIRECTION
REVERSAL

PT1

(WINDOW)

|
|

l
|
-

PT2 (CLOCK)

DIR

HOLD

F/F

+ TACH

- TACH

cp-1617

Figure 4-29

Increment Detection Timing

+ F/F

p—

F/F

——

—

——

COUNT

f—
o— c—

- F/F

—

l |

F/F

—

OVERFLOW

——

—

cm—

COUNT PULSE

OVERFLOW PULSE

l
{

F/F

SIGN

F/F

C/B

{ (
— T

CLR C/B L

U
CcP-1618

Figure 4-30

Encoder Signal Detector and Column Increment Counter Timing Diagram

4-45

4.9.4 Column Increment Counter and Carry/Borrow 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
T1, the OVERFLOW flip-flop is cleared by the 1.184 us pulse from MPCS5. 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. If the counter has just reached 9,
the SIGN flip-flop is set to a 1 and a BORROW H is sent to the MPC. If the 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 us 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 INIT routine to set the COL INC
counter to 5 and clear the C/B flip-flop.

COUNT F/F COUNT

MPC7

R3 coL NG

CLK

COLUMN R2

SouNNS

COUNTER Ri}COUNT 1

CG ROM

COL INC

MPC7

—1¢

SIGN

INCREMENT [COL INC

+F/F +INC

‘

MPC6

ROJCOUNT O

\ BORROW H MUX 1

MUX 2

MPC 4

—1
—

TM\

CARRY H MUX1

MPC
4

CLR
DEC 1 INIT L
MPC 4

LOGIC

1.184 usec

OVER-

‘

]

LD 1

CLR C/B D—-—' c

FLOW

MPC“{ CLR INIT L

1
DEC

CLOCK
MPCS

c/8B

o—

592ns
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 DEC1. This gates a 2.4 kHz signal (208H) to the speaker via a
transistor switch, (Q10) to produce an audible tone. The MPC controls the duration of the 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 DECI. 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.
+5V —AA——

§SPEAKER

SET BELL

DEC
1

MPC4

b1
BELL

CLR BELL

CHOLD

WAKE UP W.U.

MPC
8

CLOCK LOGIC

208H

MPC5

DEC1 Mpcg —LR KBH

l
D1

=
UART

MPCE

KB
HOLD

EOC

ol—XBH mux1 mpca
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.
+20
LFI

[ STEP LFL

GREY
CODE

COUNTER

-20
+20

LF2

DEC 1

PN,

_PHASE
1

PHASE 2

LF STEPPING
MOTOR

-20

HOLD

L
[LENS

COMMON

| SET HOLD

WAKE UP W.U.
MPC8

i::::x*‘

HOLD

cP-15886

Figure 4-33

Line Feed Stepper System

4-47

The relatipnship 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 amoplifier to apply a holding current to both phases
of the LF stepping motor. WU also clears the counter.

STEP LF L

sET HoLD L

i‘%

LF HOLD L

23 Ms —

ole—

{

50 | 6.8

7.5

3.7

| wTMs | MS l MS ‘ MS l

)

10 MS ——+]

P _]
LF2 H

33 MS

NOTE:
Not drawn to scale.
CcP-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, LFI1, 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 com-

Table 4-8 LF Pulse Truth Table
LF2

LF1

Hold

plete line advance takes 33 ms +5% nominal.

Step LF

After the line advance is completed, another

Step LF

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.

4.12 WAKE-UP (WU) CIRCUIT
The wake-up circuit is shown on MPCS8. 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

+12voc

REGULATOR

BRIDGE

12V

REC:;;'ER

VOLTAGE

FILTER

REGULATOR

ovoc

~12V0

‘
YV

LINE

¢,

LINE

FILTER]

VOLTAGE

oower

STEP

REGULATOR

DOWN

|TRANSFORMER

-2¥DC

—21VDC

ON/OFF
BRIDGE

45V

RECI'I‘FSER

VOLINGE

REGULATOR

+5VDC

cpP-15980

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.
Figure 4-36

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.

ECCENTRIC

ONE - WAY

CLUTCH

DRIVE SHAFT

'xfi}&i

PRINT HEAD

LEVER

CARRIAGE

P
\‘?‘\

ADJUSTMENT

PRINT BAR ENCODER

lb\

PULLEY

1/5 PITCH
BELT
TIMING

AL ,\
e

{

~\\fl|

\\[3@‘ ,

22 o

e
carriace | C0S

PRINT HEAD
FLAT CABLE

SHAFTS

DRIVE

PULLEY
cpP-n72

Figure 4-37

Carriage Subsystem

4.14.2 Ribbon Feed Subsystem
A
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 pushrod, 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 of the 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

RIBBON DRIVE
SHAFT

ECCENTRIC

PUSH

ROD

REVERSE

SENSOR

)

RATCHET

INTERPOSER

BAIL CAMMING
FOLLOWERS

INTERPOSER

cP-175

Ribbon Feed Subsystem

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

2:5 cearTRAIN

5° STEPPING MOTOR
SQUARE
DRIVE SHAFT

TRACTOR ' EED
ADJUSTING KNOB

(LD
Iy

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

)

Figure 4-38

.\ uaL
CcLUTCH
|

adjustments when preprinted forms are used.

TRAcTOR O

.«‘e/<

CP-173

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 §
UPGRADED LA36

5.1

GENERAL

Nouwkw=

The purpose of this chapter is to reflect the equipment changes incurred since the original publication.
Changes of significant importance include:
M 7723 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
LA3S
LA35

90-132V,60 Hz
180-264 V, 60 Hz
90-132V, S50 Hz
180-264 V, 50 Hz
90-132V, 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

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

..............O.rfi.

M7722
LOGIC

.‘..................

M7723

BOARD

LOGIC

BOARD

4 CONNECTOé://r
Figure 5-1

M7728

LOGIC BOARD

CONNézTORS

CP-2391

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.
1.

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 permlts printing
whenin local or on-linein half- or full-duplex mode.
2.

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/L.A36. 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

M7728 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

INPUT (IF USED)

era
(NOT

INPUT

(IF USED)

USED)

KEYBOARD

|J1 | Iusl IJZI |J4|

M7728 LOGIC

A. NO OPTIONS

BOARD

INSTALLED

TO J1

POWER BOARD

20mA SERIAL
INPUT (IF USED)

EIA

INPUT

(IF USED)
l

TO J2
KEYBOARD

(NOT

USED)

TO J2 FRONT
PANEL CONTROL

[

BOARD (DIP CONNECTOR)

LOGIC BOARD

EXPANDER MOUNTING

OPTION

(LAXX-LB)

B. ANY OPTION WITH THE
AUTO

LINE

FEED OR

AUTO

FOLLOWING EXCEPTIONS:

ANSWER

BACK OPTIONS NOT

POWERIBOARD

EIA

INPUT(IFUSED)——\

LOGIC BOARD —

INPUT

(IF USED)

20 mA SERIAL

T0 J2
KEYBOARD

INSTALLED

(NOT

USED)

TO J2 FRONT
PANEL CONTROL

BOARD (DIP CONNECTOR)

|
EXPANDER

MOUNTING

OPTION

(LAXX-.B)

C. ANY OPTION AND
AUTO LINE FEED OR AUTO ANSWERBACK

Figure 5-2

OPTIONS

INSTALLED

CP-2102

Cabling Configurations for the M7728 Logic Board
5-3

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

The rating of the ac line fuse was increased from2 A SBto 3 A SBfor 115 Vand from1 A
SBto 1.5
ASB for 230 V.

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

The 18,000 uF capacitor in the capacitor bank was replaced with a 37000 uF capacitor.
A constant voltage transformer (CVT) replaced the original transformer.

5.4.1 New Power Transformers
Upgradable LA35/L.A36s have constant voltage power transformers installed to accommodate the
increased power requirements of the options. There is a unique transformer model for S0 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

frmee MODE cmonm BAUD RATE =i
;—- 150 1

LHRE

FOX

toge

HpX®
CHAR

SET
LOCK

STD

ALY

CHARACTER SET

PAPER
DUT

300

AUTO
b4

HERE
i

DEVICE

SELECT

SELEU!
AVAIL

Figure 5-3 LA36‘Keyboard Bezel
5.6

7622-28

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

LA35/LA36 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 thé 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
Tn-State Buffer.

SET/CLR

BEL

;

BELL

SYSTEM

2.4 KHz

LINE
FEED
e Epren

LF/LF HOLD

CRYSTAL
CLOCK

1.6896MH2

PROGRAMMED
CONTROLLER

CARRY/7 BORROW INCREMENT

(MPC)
SPEED DATA

DATA

CARRIAGE

SERVO

BUS

SYSTEM

]

)

F——

CHARACTER | @
ADDRESS | «

(]

3 [ ] L ]

I'DATA

COMMUNICATIONS

INPUT

SERIAL

CONVERSION

ADDRESS

SERIAL

LOOP

BUFFER

TRANSMIT

) l

CHARACTER

BUFFER

EXPANDER

PRINT HEAD
SYSTEM

COLUMN INCREMENT COUNT

BOARD

OP TIONS

1DOT MATRIX

ROM

DRIVE

]

RECEIVE

LOOP

L ] L ] L ]

[DpaTa

INTERFACE

<JUTPUT

L L ] L ] L ]

RIBBON
SYSTEM

KEY
STROBE

L~4

KEYBOARD

SYSTEM

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 J1 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 J1 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 UART require a timing control signal to ensure that the UART 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.

CLOCK

— D 0o

— 0oL loec
INSTRUCTIONE=@ G| L

SKIP 2

JUMP 2

0 o

—aZW

SKIP 1—

CONTROL

PROGRAM

JUMP 3—= = \pc3)

CLR—»

512X8

ADDRESS

4BITS

E22 (MPC4) |4 g& ¢

CONTROL

—o ="

E9,E11

E4S

(MPC3)

=5 5
R &

@
5

e T

ROM

(MPC3)

4 BITS

ROM

DATA

BUS
+1

REG

S
<

zero [TREG=O
DETECTOR
'
E4 (MPC4)

BRING1

E10 (MPC4)

4 BIT

J I

16X 4
CONTROL
RAM

|4 BITS OPEN COLLECTOR

E3 (MPC4)

STORE

-1

REG

4 BIT GATE | go/ne 4

BRING
1
STORE
1

DATA

BMB 06

DEC 1

SKIP

—

(MPC4)

SET BELL

BELL

SYSTEM

CLRCaB *

cLR LN;; =

SETLF HOLDj

CARRIAGE

STEPPER

(MPC7)

(MPC8)

LOAD CB

ADDRESS

PNTABL

BUFFER

OUTPUT
RIA

DATA
1 (REC)
ICOMMUNICATION
INTERFACE

SINpuT TL_(MPCS)

KEY

BOARD

(MPC6)

XMT

rRoy L
KEY

BOARD |

STEERING |

1024 X 8

16 X 8

|©

ROM E48,

E53(MPC9)

PRINT HEAD
[DOT

MATRIX

SYSTEM

E37(MPC8)

E31,E41(MPC9)

3BIT

UART

cic

ENAB

EXPANDER BOARD AND OPTIONS

||
,

7 BIT

ASCII

DOT

MATRIX

CONTROL

E29 (MPC9)

OPTIONAL CHARACTER SET

|
OPTION CLOCK

SET “DE—“‘

CHARACTER

BUFFER
CHARACTER
E46
E51 | 7BIT ASCII A gUFFER
Ram | 7 BIT ASCIL

[T oxmim)

STROBE

—

GENERATOR

)

| - ————

STROBE
KEY

Ess(mpPce)| 7 BIT ASCIL X TRi-STATE

—»INC

3 BIT COLUMN INCREMENT COUNT

SERIAL

CARRY (C)

CHARACTER
BUFFER
ADDRESS

UART

—

(B)
—*BORROW

SERVO SYSTEM

LINE FEED
SYSTEM

—BIT3

LOAD DAC

(MPCB)

2 4 KHz—e|

STEP LF

|
»BIT2

4 BIT REGISTER DATA BUS

CLR BELL—={

L
»BITO

[»BIT

Voo

BELL

CLR DA
CP-2334

Figure 5-5

M7728 Control Logic Diagram

5-7

M7728
LOGIC

BOARD

XMIT
| SECTION
SERIAL <4————
ouT
J#

amum— R L] A aE— L] L]

| |

KEYSTROBE

lemmmmm
-

—

)

KEYSTROBE

[

LINE

ING
NI

FEED
CONTROL

LINE

CODE

{

FEED

GENERATOR

Jé}

KEYBOARD M.
N

————————

| AUTO LINE FEED

e e

J;Q—;%_*’m_ T
N

.
N\

KEY
BOARD

LN
N\

DATA

ANSWER

//H A

BACK

GENERATOR

[

MESSAGE

ANSWER

BACK

CONTROL

AUTO ANSWERBACK

L L CEE L R L] R L] L} L]
CcP-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 UART 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

MmICrOprocessor.

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 of the 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.

M7728 LOGIC BOARD

UART

SERlAL_l_, RECEIVE

7 BITS

fi>

SECTION

DA
______

‘

TRI-STATE |UART DATA BITS 1-7
BUFFER

CHARACTER
BUFFER

ROM

LINES

p———

]

oE———

UART ENAB

EXPANDER OPTION

l MOUNTING BOARD
I

A
L]

)

B1-DIRECTIONAL
]

\
/

MICROCONTROLLER

UFFE ::>GENERATOR

ToO
CHARACTER

;

DflTA AVAILABLE

p——

]

OPTION DATA BITS

OPTIONS
ALLIN RECEIVE

]

ah———

OPTION
D;Q

PATH

CLEAR DATA AVAILABLE

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
X10 Probe

Tektronix

P 6010 (or equivalent)

Slip-on-Tip

Tektronix

013-0090-00 (or equivalent)

EZ Hook

Pomona Electronic

3925 (or equivalent)

Resistor

30to 50 2, 10 W minimum

Resistor

1000 2, 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.

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 resistoer 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.

Set the POWER switch to OFF.

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

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.

Apply +21 V to the servo motor by connecting the jumpers and the resistor between R104

Set the POWER switch to ON. The motor should rotate in the positive direction (clockwise

Check the waveforms at the test points shown in Figures 6-3 through 6-9.

Set the POWER switch to OFF and connect -21 V (R105 bottom lead) to the motor as

Repeat step 5. The motor should rotate in the negative direction (counterclockwise).

Check the waveforms at the test points shown in Figures 6-10 through 6-14.

(bottom lead) and the servo fuse F2 (Figure 6-1).

as viewed from the front of the LA36).

shown in Figure 6-2.

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

11.

Reinstall fuse F1 on the power board, and set the POWER switch to ON.

lead to the servo fuse (F2).

30-50 OHM
10 WMIN

JUMPER

POWER BOARD

R104 R106

SERVO FUSE

F1 (REMOVED DURING TEST)

Physical Connection

SERVO FUSE

MOTOR

JUMPER

R104

————————————
N\
W———————— 80— WVW\—@

30-50 OHM
10W MIN
TEST

*av

RESISTOR
CP-2207

b.
Figure 6-1

Electrical Connection
Encoder +21 V Test Setup

6-3

30
- 50 OHM

10
W MIN

JUMPER

R104

R106

POWER BOARD

|
SERVO FUSE

F1 (REMOVED DURING TEST)

Physical Connection

SERVO FUSE

MOTOR

R105

JUMPER

30-50 OHM
10W MIN
TEST

-2V

RESISTOR
CpP-2206

Figure 6-2

Electrical Connection

Encoder -21 V Test Setup

8433-5

START OF ENCODER SIGNAL PROCESSING TEST WAVEFORMS

Start of Positive-Direction Encoder Tests

SCOPE SETUP

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

VARIABLEAPPROX.

75 us/DIV

4.5 VDC

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,
INT, POS

CH1 to +PT1 at power board J4-5

GND -

CH2 to +PT2 at power board J4-6
M-0674

Figure 6-3

+PT1 and +PT2 Waveforms

SCOPE SETUP

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

20 us

TRIG MODE:

NORMAL

4vV—

TRIG SOURCE:

CH1,AC,

GND

CH1 to +PT1 at:

4V7
GND
_

POS, INT
M7722 E6-8
M7723 E2-8
M7728 E18-8

CH2 to +PT2 at:

M7722 E6-6
M7723 E2-6

Figure 6-4

+PT1 and +PT2 Schmitt Waveforms

6-5

+INC MAY OCCUR

SCOPE SETUP

ANYWHERE DURING

THIS TIME

GND —
JITTER

COUNT F/F MAY SET

COUNT F/F CLEARED

ANYTIME FROM 0 TO

592 ns LATER

1.184 us AFTER +INC

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

500 ns

TRIG MODE::

NORMAL

TRIG SOURCE:

CH1,AC,

CH1 to -INC at:

M7722 E8-9

INT, POS

M7723 E7-9

GND ——

M7728 E60-9

M7722 E4-9

CH2 to COUNT at:

M7723 E13-9

M7728 E45-9

M-06877
Figure 6-5

+INC and COUNT Flip-Flop Waveforms

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

200 ns

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,

CH1 to COUNT F/F at:

M7722 E4-9

GND —

M7723 E13-9

M7728 E45-9

GND ——
CH2 to COUNT puise at:

M7723 E18-8

M-0669

60 ns

M7728 E49-3

NOTE:

50 ns pulse (CH2) may vary in response to COUNT puise (CH1).

Figure 6-6

COUNT Flip-Flop and COUNT Pulse Waveforms

6-6

M7722 E29-8

1.184 ”—.i

SCOPE SETUP
. VOLTS/DIV:

. VERTICAL MODE:

ALT

.HORIZ DISPLAY:

TIME/DIV:

200 ns

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,

39V

GND

39V~

INT, POS

CH1 to COUNT F/F at:

M7722 E4-9
M7723 E13-9

GND

M7728 E45-9

CH2 to CLR +/-F/F at:

M7722 E9S-6
M7723 E3-6

M7728 E49-6

NOTE:

118.4 us varies with the speed of the encoder motor.

Figure 6-7

COUNT Flip-Flop and CLR * Flip-Flop Waveforms

118.4 u,_..‘

SCOPE SETUP

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

20 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,INT,POS

CH1 to +INC at:

M7722 E8-9
M7723 E7-9
M7728 ES0-9

M-0671

NOTE:

118.4 us varies with the speed of the encoder motor.

Figure 6-8

+INC Waveform

SCOPE SETUP

VOLTS/DIV:

VERTICAL MODE:

ALT

HdRIZ DISPLAY:

TIME/DIV:

60 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,INT,NEG

CH1 to +TACH at:

M7722 Q11-C
M7723 Q11-C

M7728 Q11-C

GND

|
M-0672

—>|

76 us

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 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,
INT, POS

CH1 to PT1 at power board J4-5

CH2 to PT2 at power board J4-6
M-0673

Figure 6-10

-PT1 and -PT2 Waveforms

6-8

SCOPE SETUP

GND

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

10 us

TRIG SOURCE:

CH1,AC, POS, INT

CH1 to -PT1 at:

M7722 E6-8
M7723 E2-8
M7728 E18-8

GND ——

CH2 to -PT2 at:

M7722 E6-6
M7723 E2-6
M7728 E18-6

M-0675

Figure 6-11

-PT1 and -PT2 Schmitt Waveforms

—-INC MAY OCCUR

SCOPE SETUP

ANYWHERE DURING

THIS TIME

VOLTS/DIV:
. VERTICAL MODE:

ALT

HORIZ DISPLAY:

COUNT F/F MAY

ANY TIME FROM
O TO

. TIME/DIV:

500 ns

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,

1.184 us AFTER -INC§

ROUNTE

592 ns LATER

INT, POS
|

CH1 to -INC at:

GND

M7722 E8-6
M7723 E7-6
M7328 E50-5

CH2 to COUNT at:

M7722 E4-9
M7723 E13-9

M-0676

Figure 6-12

-INC and COUNT Flip-Flop Waveforms

6-9

M7728 E46-9

OND

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

20 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,

INT, POS

CH1 to -INC at:

M7722 E8-6
M7723 E7-5

M7728 E5S0-6

M-0678

NOTE:

118.4 us varies with the speed of the encoder motor.

Figure 6-13

-INC Waveform

SCOPE SETUP

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

60 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,DC,

INT.NEG

CH1 to -TACH at:
GND —

M7722 Q12-C
M7723 Q12-C

M7728 Q12-C

M-0679

__, 76 us I__

rigure 6-14

-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 of Q3 to ground. This causes the servo motor to reverse direction and run at

Check the waveforms at the test points as indicated in Figures 6-23 through 6-28.

15.24 cm/second (6 inches/second).

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 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,POS.INT

CH1 to INC at:

M7722 E5-9

GND —

M7723 E12-9

M7729 E54-9
GND—

M7722 E5-11

CH2 to 76 us

M7723 E12-11

CLOCK at:

M7728 E54-11

M-0687

Figure 6-15

-INC and 76 us CLOCK Waveforms

SCOPE SETUP

76 us

16V

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

10 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,

GND

POS., INT

CH1 to TACH at Q12-B on logic board
CH2 to TACH at Q12-C on logic board

0.8V

M-0680

76 us

NOTE:

Turn power off when connecting scope leads.

Figure 6-16

-TACH Waveforms at Q12-B and Q12-C

6-12

SCOPE SETUP

76 us

GND ——

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

10 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,POS, INT

CH1 to -TACH at:

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

GND —

CH2 to 76 us at:

M7722 Eb-3

M7723 E12-3
M7728 EB4-3

M-0681

Figure 6-17

z 1-3 111d

-TACH and 76 us Waveforms

Al
SCOPE SETUP

1.5V

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

GND I
GND—

200 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,POS, INT

CH1 to -TACH
at:

M7722 Q12-B
M7723 Q12-B
M7728 Q12-B

CH2 to SUM at:

M7722 J1-B (1-6)

M7723 J1-B (E1-6)
M-0682

Figure 6-18

-TACH and SUM Waveforms at J1-B

6-13

M7728 J1-B (E27-6)

SCOPE SETUP
CH1=2V

VOLTS/DIV:

CH2=b6V

1.6V
GND

GND

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

600 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC, POS, INT

CH1 to -TACH at:

M7722 Q12-B

M7723 Q12-8

-6V

M7728 Q12-B

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

Figure 6-19

-TACH and MD Waveforms

SCOPE SETUP

| voLts/piv:

L o

"-#
avVv

430 ms
=

GND

el
edeteniatne llLl"Ellll Trevqivirvgevrsquent
L breeelbntptione
rreryrvrypverviresngyvevi_pggurd

VERTICAL MODE:

CH1

HORIZ DISPLAY:

TIME/DIV:

60 ms

TRIG MODE:

NORMAL

TRIG

SOURCE:

CH1,AC,
NEG, INT

CH1 to INC at:

M7722 E30-9

M7723 E22-9
+

M7728 E44-9

——

+
M-0725

NOTE:

Waveform is flashing on and off scope.

Figure 6-20

INC Waveform

6-14

SCOPE SETUP
VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

2ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,

GND——

CH1 to COL INC
COUNT (MSB) at:

— |
GND
CH2 to COL INC

Figure 6-21

| m-o0es4

15 ms

COUNT 2 at:

POS, INT

M7722 E16-7
M7723 E16-7
M7728 E43-7
M7722 E16-6
M7723 E16-6
M7728 E43-6

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

SCOPE SETUP

GND —

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

5ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,INT,POS

CH1 to COL INC

COUNT 3 (MSB) at:
GND —

CH2 to BORROW H at:

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

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

}<¥
Figure 6-22

30 ms

4—I

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

7/ \NC MAY OCCUR
REGION

GND

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

10 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,POS, INT

CH1 to +INC at:

M7722 E3-9

M7723 E17-9
M7728 E40-9

GND~——
CH2 to -76 us

CLOCK at:

-| |e—2 us

M7723 E17-11
M7728 E40-11

M-0686

Figure 6-23

I‘

M7722 E3-11

76 uS

+INC and 76 us Waveforms

SCOPE SETUP

GND——

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

10 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,POS, INT

CH1 to +TACH at:

M7722 E3-5
M7723 E17-5
M7728 E40-5

GND —
CH2 to 76 us at:

M7722 E3-3
M7723 E17-3

M-0688

Figure 6-24

+TACH and 76 us Waveforms

6-16

M7728 E40-3

SCOPE SETUP

76 us

15V_1

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

10 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,

POS, INT
CH1 to +TACH at:

M7722 Q11-B
M7723 Q11-B

o8yv —

M7728 Q11-B

CH2 to +TACH at:

Figure 6-25

—

76 us

M7722 Q11-C
M7723 Q11-C

M7728 Q11-C

M-0689

+TACH Waveforms at Q11-B and Q11-C

1.3 mg=——

SCOPE SETUP

GND—

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV::

2000 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC, POS, INT

CH1 to +TACH at:

M7722 Q11-B
M7723 Q11-B

M7728 Q11-B
GND ———

CH2 to SUM at:

M7722 J1-B (E1-6)

M7726 J1-B (E1-6)
M-0690

Figure 6-26

+TACH and SUM Waveforms

6-17

M7728 J1-B (E27-6)

SCOPE SETUP

76 us~——p

GND ——

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

500 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC, POS, INT

CH1 to +TACH at:

M7722 Q11-B
M7723 Q11-B

M7228 Q11-B

GND —

CH2 to MD at power board J4-8

M-0691

Figure 6-27

+TACH and MD Waveforms

SCOPE SETUP

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

6 ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC, POS, INT

CH1 to COL INC
COUNT 3 (MSB)at:
|

M7722 E16-7
ng :lg;’
i

4V —F-—

GND —1—

GND—1—

CH2 to CARRY H at:

M7722 E7-6
M7723 E10-8

M-0692

Figure 6-28

M7728 E16-8

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,

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

SCOPE SETUP

|‘___.23 ms ___l

+21 + 5
GND

—
—p—

+21 + BV —

+21 + BV —a—

VOLTS/DIV:

20V

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

5ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC, NEG, INT

GND —p—

CH1 to PHASE 1 at power board J5-7

21 + BV =l

CH2 to PHASE 2 at power board J5-6

5.0

6.8

7.5

3.7 ,

Figure 6-29

M-0693

LF Motor Phase 1 and Phase 2 Waveforms

6-19

SCOPE SETUP

21 £ 8V

GND —i—

21
£ 6V

VOLTS/}D|V:

20V

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

5ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,POS, INT

CH1 to LF1 at power board Q34-C

GND 0

CH2 to LF2 at power board Q36-C

5.0

6.8

7.5

3.7

M-0694

e
2 3 NS e

Figure 6-30

LF1 Waveform at TPA12 and LF2 Waveform at TPA1S5

SCOPE SETUP

GND —

-21V

—

VOLTS/DIV:

20V

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

5ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,

GNDT

21V
+ 5V -

POS, INT
CH1 to LF1 at power board Q35-C
Py

CH2 to LF2 at power board Q37-C

6.0
ms

|[ms

23 ms

Figure 6-31

LF1 Waveform at TPA13 and LF2 Waveform at TPA16

6-20

SCOPE SETUP

5V _

0.6 V.

oo L

o6V

VOLTS/DIV:

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

Sms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,NEG, INT

CH1 to LF1 at power board Q39-C

CH2 to LF2 at power board Q38-C

501

6.8

7.5

|3.7

M-0696

fe——— 23 ms ——|

Figure 6-32

LF1 Waveform at TPA14 and LF2 Waveform at TPA17

SCOPE SETUP

VOLTS/DIV:

CH1=20V
CH2=2V

GND

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

5ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC, NEG, INT

CH1 to LF motor common return at
power board J5-4

CH2 to LF HOLD at power board J1-29 (Q33-B)

t—— 22 MS _—>|
Figure 6-33

M-0697

LF Motor Common Return and LF HOLD Waveforms

6-21

SCOPE SETUP

GND

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 E28-10
CH2 to LF2 at:

5.o|

6.8

7.6

|3.7

M7722 E24-5
M7723 E8-8

M.0698

M7728 E28-8

23 ms

Figure 6-34

LF1 Waveform at J1-JJ and LF2 Waveform at J1-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

GND ——

M7728 E28-10
CH2 to LF HOLD at:

M7722 E29-6

M7723 E5-5
M-0699

Figure 6-35

LF1 Waveform and LF HOLD Waveforms

END OF LF STEPPING TEST WAVEFORMS

6-22

M7728 E37-5

6.1.1.4
circuit.

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

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 W1 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

SCOPE SETUP

GND ——

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

100 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,
NEG, INT

CH1 to BELL source at power board J5-1
CH2 to BELL SINK at power board J5-2

GND ——

l‘__-416 us

Figure 6-36

M-0700

BELL Source and BELL SINK Waveforms

6-23

106 ms

BURST

‘w

) 1 1

]

i 1 (h

SCOPE SETUP
N

VOLTS/DIV:

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

TRIG MODE:

NORMAL

1
B

416 us

PERIOD

POS., INT
4V

CH1 to BELL SINK at power board J5-1

CH2 to BEL at:

M7722 E36-5

M7723 E14-5
_

M7728 E34-5

106 ms

]

—

[l
MO0726

Figure 6-37

BELL SINK and BELL Waveforms

SCOPE SETUP

4V j

GND —

VOLTS/DIV:

VERTICAL MODE:

CH1

HORIZ DISPLAY:

TIME/DIV:

20 ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,POS.INT

CH1 to KBH H at:

M7722 E51-8
M7723 E22-6
M7728 E30-6

M-0701

NOTE:

This is a difficult waveshape to observe.

Figure 6-38 KBH H Pulse Waveform

END OF BELL TEST WAVEFORMS

6-24

6.1.1.5 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

Test Point

M7722

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

Character

M7723

M7728

E55-26, E56-4
E55-27, E56-6
- E55-28, E56-10
ES55-29, E56-12

E58-26, E59-4
E58-27, E59-6
E58-28, E59-10
ES58-29, E5S9

E55-26, E41-4
ES55-27, E41-6
E55-28, E41-10
E55-29, E41-12

0
1
0
1

E55-30, E5S7-4
E55-31, E57-6
E55-32, E57-10

E58-30, E60-4
ES8-31, E60-8
E5S8-32, E60-10

E55-30, E36-4
E55-31, E36-6
E55-32, E36-10

1
0
1
0
1
0
1

Table 6-3

Character Buffer Test

Test Points

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

Character

M7722

M7723

M7728

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

1
0
1
0
1
0
1

6-25

0
1
0

START OF PRINTABLE CHARACTER TEST WAVEFORMS
-

600 us

SCOPE SETUP

VOLTS/DIV:
4V

CH1=2V;
CH2=20V

——

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

100 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,

A 4

GND ——

+20 v

“

I
60V

-20 V

—

NEG, INT
CH1 to HD EN at power board
J1-4, Q22-B

CH2 to SOL1-SOL7 at power
|

600 us

board J6

M-0702

pins 8,

12, 4,

16, 6, or 4 (see note)

(@17-C, Q19-C, Q1-C, Q20-C,
NOTE:

Q18-C.

Pin numbers are marked on J6.

Figure 6-39

Q16-C.

or Q21-C)

HD EN and SOL Waveforms at J6

SCOPE SETUP

VOLTS/DIV:

CH1=2V
CH2=56V

CH2

GND |

CH1

48Yv

23V

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

1ms

TRIG MODE:

TRIG SOURCE:

CH2,AC,

GND

POS,

INT

CH1 to HS1-HS7 at:

{

M7722 E25-4, E25-6, E20-4

E20-6, E20-8, E25-8, E20-10
M7723 E28-4, E28-6, E256-4

E25-6, E25-8, E28-8, E25-10
M-0703

NOTE:

M7728 E47-1, E47-4, E47-10

E47-13, E52-1, E52-4, R52-10

Q38 has been changed to Q8 on REV T power board.
CH2 to SD1-SD7 at power board:

Figure 6-40

HS1 and SD1 Waveforms
6-26

Q6-E, Q14-E, Q2-E, Q38-E (see note),

Q12-E, Q4-E, and Q12-E

SCOPE SETUP

VOLTS/DIV:

CH1=2V
CH2=6V

CH2

GND

=23V

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

1ms

TRIG MODE:

TRIG SOURCE:

CHa2V,
AC,POS, INT

CH1 to HS1-HS7 at:

M7722 E25-4, E25-6, E20-4

E20-6, E20-8, E25-8, E20-10
M7723 E28-4, E28-6, E25-4, E26-6
E25-8, E28-8, E25-10
M-0704

M7728 E47-1, E47-4, EA7-10, E47-13

NOTES:

E52-1, E52-4, ES2-10

Q38 has been changed to Q8 on REV T power board.

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

CH2 to SD1-SD7 at power board:

Q6-B, Q14-B, Q2-B, Q38-B (see notes),
Q12-B, Q4-B, and Q10-B

Figure 6-41

HS1 and SD1 Waveforms
SCOPE SETUP
VOLTS/DIV:

CHi=2V

CH2=10V

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

1ms

TRIG MODE:

TRIG SOURCE:

CH2, AC,

48V

|
GND

GND

POS, INT

CH1 to HS1-HS7 at:

M7722 E25-4, E25-6, E20-4

E20-6, E20-8, E25-8, E20-10

M7723 E28-4, E28-6, E25-4, E26-6
E25-8, E28-8, E25-10
M-0705

M7728 E47-1, E47-4, E47-10, E47-13
E52-1, E62-4, E52-10

CH2 to SD1-SD7 at power board:
Q7-C. Q15-C, Q3-C, @9-C,
Q13-C, Q6-C, and Q11-C

Figure 6-42

HSI1 and SD1 Waveforms

6-27

SCOPE SETUP

VOLTS/DIV:

CH1=2V
CH2=10V

4.8V —

GND

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

Tms

TRIG MODE:

TRIG SOURCE:

CH2,AC,

_Al_

NEG, INT

CH1 to HS1-HS7 at:

M7722 E25-4, E25-6, E20-4,
E20-6, E20-8, E25-8, E26-10

M-0706

NOTE:

M7723 E28-4, E28-6, E25-4, E26-6

E25-8, E28-8, E265-10

Q38 has been changed to Q8 on REV T power board.
M7728 E47-1, E47-4, EA47-10, E47-13
E52-1, E52-4, E52-10
CH2 to SD1-SD7 at power board:

Q6-C, Q14-C, Q2-C, Q38-C (see note),
Q12-C, Q8-C, and Q10-C

Figure 6-43

HSI1 and SD1 Waveforms

6-28

SOLENOID NO. 1

GND —

GND ——o

HS1

SCOPE SETUP

VOLTS/DIV:

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

5ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH2, NEG, INT

CH1 to HD EN at:

M7722 E39-8,

M7723 E18-6

M7728 E39-6
CH2 to HS1-HS7 at:
M7722 E25-4, E25-6, E20-4,
E20-6, E20-8, E25-8, E20-10

SOLENOID NO. 7

M7723 E28-4, E28-6, E25-4, E26-6

GND ~—

E25-8, E28-8, E25-10

M7728 E47-1, E47-4, E47-10, E47-13
E52-1, E62-4, E52-10
Pulse moves one position to the right
for each new measurement: HS1-HS7.

GND —

HS7

Figure 6-44

HD EN and HS1 Waveforms at J1

6-29

SCOPE SETUP

VOLTS/DIV:

CH1=2V

5V e

CH2=8V

anp —1

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

6ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,

GND

NEG. INT

M7722 E39-8

CH1 to HD EN

M7723 E18-6

atJ1 (R68):

M7723 E39-6

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=2VDC COUPLED
CH2=1 VAC COUPLED

GND—~—

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

200 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,POS. INT

GND ——

WARNING

Float scope power line before
making these connections.

M-0709

CH1toHDEN at:

M7722 E39-9

M7723 E35-9
M7723 E37-9
CH2 to SD1-SD7 at power board Rb52,

R53, R1, R54, R56, R51, R55
CH2 probe ground to -21 V

Figure 6-46

HD EN Voltage Waveform and SD Current Waveform

6-30

SCOPE SETUP

GND—t—

4 v

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

200 ns

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,NEG, INT

CH1 to WRITE BUFF Lat:

M7722 E60-10
M7723 E38-10

M7728 E30-10
GND
CH2 to CLR R DONE at:

M7722 E60O-8
M7723 E38-8

M7728 E30-8

M-0710

NOTE:

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

Figure 6-47

WRITE BUFF L and CLR R DONE Waveforms

SCOPE SETUP

GND

VOLTS/DIV;

VERTICAL MODE:

CH1

HORIZ DISPLAY:

TIME/DIV:

600 ns

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,NEG, INT

CH1 to KEY STB at:

M7722 E67-4

M7723 E6O-12

M7728 E66-2

M-0711

NOTES:
1.

Scope intensity may have to be turned up to

make this waveshape visible.
2.

This pulse is 5600 ns wide on earlier keyboards.

Figure 6-48

KEY STB L Waveform

6-31

SCOPE SETUP

VOLTS/DIV:

1 VAC COUPLED

VERTICAL MODE:

CH1

HORIZ DISPLAY:

TIME/DIV:

20 ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,POS, INT

CH1 to power board Q25-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
mode.
1.
2.

Clock Test - The clock test checks all clock frequencies and time periods in the initialize

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
SCOPE SETUP

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

200 ns

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC, POS, INT

CH1 to 592 ns at:

M7722 E64-10
M7723 E34-10

M7728 E19-10

CH2 to CLK H at:

M7722 E64-6
M7723 E34-6

M-0713

Figure 6-50

CLK H and 592 ns Waveforms
6-32

M7728 E19-6

SCOPE SETUP

GND —

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

200 ns

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC, NEG, INT

CH1 to 1.184
s at:

M7722 E13-1
M7723 E21-1

GND —

M7728 E19-10

CH2 to 592 ns at:

M7722 E13-14
M7723 E21-14

\M.0714

Figure 6-51

M7728 E66-12

592 ns and 1.184 us Waveforms

SCOPE SETUP

GND ——

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

TRIG MODE:

NORMAL

TRIG SOURCE

CH1,AC, NEG, INT

CH1 to 9.4 us at:

M7722 E26-1
M7723 E30-1

GND

M7728 E68-1

CH2 to 76 us at:

M7722 E26-11
M7723 E30-11

76 us

Figure 6-52

M-0715

|
9.4 us and 76 us Waveforms

6-33

M7728 E68-11

SCOPE SETUP

GND ——

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

2 us

TRIG MODE:

NORMAL

TRIG SOURCE

CH1,AC,NEG, INT

CH1 to 9.4 us at:

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

GND ——

CH2 to 19L at:

M7722 E26-9
M7723 E30-9

M7728 EG8-1

Figure 6-53

9.4 us and 19L us Waveforms

SCOPE SETUP

GND —

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

10 us

TRIG MODE:

NORMAL

TRIG SOURCE

CH1,AC,NEG, INT

CH1 to 18.8 us at:

M7722 E26-9

M7723 E30-9
M7728 E68-9

—

CH2 to 76 us at:

76 us

Figure 6-54

M-0717

18.8 us and 76 us Waveforms

6-34

M7722 E26-11

M7723 E30-11
M7728 E68-11

SCOPE SETUP

_.I |<-—-1 8.8 us

GND ——

@ic

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

20 us

TRIG MODE:

NORMAL

TRIG SOURCE

CH1,AC,POS, INT

CH1 to 18.8 us at:

M7722 £26-9

ana

M7723 E26-9
M7728 E68-9

GND ——
CH2 t0o 4.8 kHz at:

M7722 E63-11

M7723 E48-11

416 us

18.8 us and 4.8 kHz Waveforms

SCOPE SETUP

Figure 6-55

M7728 E63-11

M-0718

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

60 us

TRIG MODE:

NORMAL

TRIG SOURCE

CH1,AC, POS, INT

GND —

CH1 to 208 H:

M7722 E26-12

M7723 E30-12
M7728 E68-12

GND—
CH2 t0 4.8 kHz at:

M7722 E63-11

M7723 E48-11

'—o-|.— 58 us

Figure 6-56

M-0719

208 H and 4.8 kHz Waveforms

6-35

M7728 E63-11

SCOPE SETUP

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

100 us

TRIG MODE:

NORMAL

TRIG SOURCE

CH1,AC,POS, INT

4V _j

GND —

CH1 to 37.6 us :

M7722 E26-8

M7723 E30-8
GND

M7723 E68-8

CH2 to 1.76 kHz at:

M7722 E68-11
M7723 E47-11

’0—- 568 us ——‘I
Figure 6-57

M7728 E67-11

M-0720

37.6 us and 1.76 kHz Waveforms

SCOPE SETUP

GND

VOLTS/DIV:

VERTICAL MODE:

ALT

HORIZ DISPLAY:

TIME/DIV:

200 ns

TRIG MODE:

NORMAL

TRIG SOURCE

CH1,AC,POS, INT

CH1 to 529 ms at M7728 E61-10
GND

CH2 to option clock at M7728 E61-8

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 any on-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 mA 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.

Connect the transmit and receive loops back-to-back as shown in Figure 6-59.

Set the POWER switch to ON.

Set the BAUD RATE switch to 300.

Current Loop Test

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

Momentarily press the SHIFT key and “*” keys (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 6 and 7 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.

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

4.8 kHz

150

2.4kHz

110

1.76 kHz

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

6-37

L START OF CURRENT LOOP INTERFACE WAVEFORMS ]

I LOGIC BOARD
M7728

/r:

1000 OHM
174 WATT

JUMPER

\JUMPER USING MATE-N-LOK PINS

l LOGIC BOARD

—

L
o]~
<

r‘

bt
rn

CONNECTION

-12y ——34—0—

Z
(2]

PHYSICAL

1000 OHM

[Pr——

20 MA LOOP

Jé
—f
@

I
I
|
|

;

O
m
)

M7722/M7723

-mb

I
I

J3
1000 OHM
1/4 WATT

2
—O-

20 MA

TRANSMIT

5
O
3

l&—— JUMPER

O-

+12V

O-

RECEIVE

ELECTRICAL CONNECTION
CcP-1606

Figure 6-59

Current Loop Test Setup

6-38

SCOPE SETUP

VOLTS/DIV:

CH1=2VDC COUPLED

CH2=1 VAC COUPLED

GND e

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

5ms

TRIG MODE:

NORMAL

TRIG SOURCE

CH1,AC, POS, INT

CH1 to Sl at:

M7722 E62-1
M7723 E52-1
M7728 E60-4

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

NOTE:
Mark = GND; Space = 56 Vor 1.5 V.

Figure 6-60

Loop Receiver Waveforms

SCOPE SETUP

VOLTS/DIV:

CH1=2VDC COUPLED
CH2=1VAC COUPLED

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

5 ms

TRIG MODE:

NORMAL

TRIG SOURCE

CH1,AC,NEG, INT

GND ——

]
CH1

at:

GND =—

M7722 E66-11
M7723 EB2-11
M7728 E61-11

CH2 to transmit at logic board J3-5
M-0723

NOTE:
Mark = GND; Space = 56 Vor 1.5 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.
Connect the transmit and receive loops back-to-back as shown in Figure 6-62.
Set the POWER switch to ON.

Set the BAUD RATE switch to 300.
Simultaneously press the SHIFT key, “*’’ key, and REPEAT key to get a series of printing
characters.
Check the waveforms at the test points listed in Figure 6-63.

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

fiogic BOARD

| M7722, M7723, M7728

)

| R PP

l
(

{ JUMPER

I
I

\--l-- -n.....-n.....-—-'-_--._.--n-.-..-..___....-‘_-.___..-J
PHYSICAL

CONNECTION

_J4a

2 | s1.

JUMPER —
-

4 | s.0.

ELECTRICAL CONNECTION
CP-1623

Figure 6-62

Serial Line Test Setup

SCOPE SETUP

GND

VOLTS/DIV:

VERTICAL MODE:

CHOP

HORIZ DISPLAY:

TIME/DIV:

5 ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC, POS, INT

CH1 to SO at:

M7722 E29-12
M7723 E18-12

M7728 E60-12

GND =

CH2 to Sl at:

M7722 E66-6

M7723 EB3-2
M-0725

NOTE:

5V = SPACE: GND = MARK

Figure 6-63

Serial Output and Serial Input Waveforms

END OF SERIAL LINE INTERFACE WAVEFORMS

6-41

M7728 E42-11

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

45V

VOLTS/DIV:

VERTICAL MODE:

ALT

SWEEP:

SINGLE SWEEP

TIME/DIV:

100 ms

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1, AC, EXT, POS

CH1 to Wake-Up at:

M7722 E36-1
M7723 E14-1

M7728 E34-1

(See note 2.)
Notes:

1. This waveform is a dot moving across the scope.
Upon power application the dot is a logic zero,

it then goes to a logic one when wakeup is completed.

2. The transformer secondary power board (J3-4) was
used to trigger the scope.
M-0558

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 1-11 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
LA3S.

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 F1
(3ASloBloat 115V or
1.5 A Slo Blo at 230 V).

Reference

Replace.

POWER switch

Switch failure

Replace S1.

Power harness

Poor connections

Unplug printer,
check harness.

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

b. Print head does not move.

Not plugged in or

connected to J1

loose

Servo fuse F2 (front of
printer). Early printers,
check F1,2A SB on

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,-12V, +5V, | Table 6-5

Servo fuse F2 (front

Check fuse and replace
(2 A Slo Blo).

power board.

Servo fuse

of printer). Early
printer, check F1

on power board.

6-44

Check harness and jumper.

Voltage jumper

+21 V,and -21 V

Table 6-4 Troubleshooting Chart (Cont)

Problem Area

2. b. Cont

Logic board, power board, | Faulty speed circuit on | Connect probe to J1-B
carriage, or encoder motor

logic board, open on

power board, jammed
carriage, or inoperative
motor

Voitage

goes low (-10 V)
then high (+10 V)

Reference

Action

Probable Cause

Symptom

Speed circuits,
Paragraph 6.1.1.2

(sum output) on logic
board. Set PRINTER

switch (power) OFF then
ON and observe voltage.

YES

Fault logic board.
Check speed circuit.

1. Check for opening
on power boerd or

blown fuse.

2. Check for faulty
encoder motor.

3. Check for head
jam.

MPC portion of logic

Replace logic board.

board

3. Carriage moves violently or

Power board

Loss of low voltage

or goes to either margin and
Logic board
NOTE

If print head moves violently, remove
the servo fuse prior to checking dc

voltages (logic board), clock pulses,
and servo amp (power board).

Table 6-5

+21 V,and -21 V.

erratically from margin-to-margin
stays there.

Check +12 V,-12V,+5V,

Encoder

Loss of clock signals

Perform clock test.

No wake-up

Perform wake-up test.

Encoder out of

Perform encoder

adjustment.

Paragraph 6.1.1.6

Paragraph 8.2

6-45

Table 6-4 Troubleshooting Chart (Cont)

Symptom

Problem Area

3. Cont

Logic Board

Probable Cause

Action

Reference

Encoder processing

Perform encoder signal

Paragraph 6.1.1.1

processing test.

'NOTE
To obtain negative and

positive drive waveforms,

perform setup described
in Paragraph 6.1.1.2.

Servo amp

Power board

Check waveshapes and

Negative drive, Figure 6-19

servo amp circuits on
power board schematic.

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

is pressed (printer is in local mode).
NOTE

Keyboard does not work when
printer is out of paper.

Paper

Line feed motor

Paragraph 3.4

Paper jammed/feed

holes torn

Check paper alignment.

Line feed fuses,
motor or tractor drive

a. Pressin and turn Paper | Chapter 7, tractor and
Advance knob to check | tractor shaft replacement

shafts and tractor

for tractor and tractor

assemblies binding

shaft binding.

b. Turn Paper Advance
knob to check for

procedure

Chapter 7, stepping motor
replacement procedure

motor and idler gear
binding

Keyboard

Press space bar. No

Keyboard
-

Paragraph 6.1.1.5

response when space bar
is depressed. Check and
replace keyboard or

keyboard cable. If printer

responds, continue with
troubleshooting chart.
Power board

4. No line feed when LINE FEED key

LF motor fuses blown

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

board.

6-46

Table 64 Troubleshooting Chart (Cont)

Symptom

Problem Area

4. Cont

Probable Cause

Action

Reference

Amplifier output signal§ | Perform line feed stepping | Paragraph 6.1.1.3

missing

test and check:

{

LF1 at Q34-C and

Figure 6-30

" | LF2 at Q36-C

LF1 at Q35-C and

. Figure 6-31

LF2 at Q37-C

LF1 at Q39-C and

Figure 6-32

LF2 at Q38-C.

LF HOLD switch

LF HOLD at Q33-C and
LF MOTOR COMMON

signals missing.

Figure 6-33

at Q33-B

Logic board

Grey Code Counter

Perform line feed stepping | Paragraph 6.1.1.3

output missing

test and check:
LF1 at M7728, E31-8 and | Figure 6-36
LF2 at M7728, E31-6.

Tractors

LF HOLD flip-flop
output missing

LF1
LF HOLD

Figure 6-35

Not feeding—worn or

Check, align, or replace.

Chapter 7

| Check, align, or replace.

Chapter 7

Check, align, or replace.

Chapter 7

Check, align, or replace.

Chapter 7

broken pin or out of
alignment

Shafts

Binding

Clutch

Binding broken

Gears

Broken teeth,
insufficient or

excessive backlash

6-47

Table 64 Troubleshooting Chart (Cont)

Symptom

Problem Area

Probable Cause

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

Loudspeaker

Open voice coil

| Action

Reference

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

Perform bell test and check:| Paragraph 6.1.1.4

M7722, E36; M7723,

E14;,M7728, E34

BEL SOURCE at J5-1 and | Figure 6-36
BEL SINK at J5-2

BEL SINK at J5-2 and

Figure 6-37

BEL at M7722, E36-5;
M7723, E14-5;

M7728, E34-5

208 H at M7722, E26-12;

Figure 6-56

M7723, E30-12;

M7728, E68-12.

KB HOLD flip-flop ES1 | Check KBH-H at

Figure 6-38

M7722,E51-8;
M7723, E22-6;

M7728, E30-6 for a high

(KBH must be high for any

printable character).

6. No printout when “\” (slash)
key is pressed; head does not

move (LINE/LOC switch in LOC).

Keyboard

CTRL and Bell keys

Check keyboard keys

Logic board

PNTABL HI signal

Check the following:

Paragraph 6.1.1.5

M7722, E25-10

PNTABL H = Approximately +4 V

M7723, E44-8

PNTABL = Approximately 0.8 V

M7728, E61-6

6-48

Table 64 Troubleshooting Chart (Cont)

Symptom

Problem Area

Probable Cause

Action

Reference

7. No printout when “\” (slash)

Carriage

Carriage Adjustment

Perform impression

Paragraph 3.4.2

Ribbon

Replace ribbon.

Paragraph 3.5

Ribbon assembly, ribbon

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

key is pressed. However, carriage

moves across carriage bar and head

solenoids sound as if they are firing.

lever is not set correctly. | adjustment.

feed does not reverse

or feed.
NOTE

Ribbon runs out of
ink due to repeated
printing on the same

portion of the ribbon.

8. Print head does not fire when
pressing ‘“\” key. However,

carriage moves across carriage bar.
Power board

Power fault

Check +21 Vand -21 V
at power board circuit
R104 and R105. Replace
appropriate components

or power board.

Voltage reference

Check Q25-E.

Figure 6-49

NOTE

Head will not fire
if V reference

equals -21 V.

6-49

Table 64 Troubleshooting Chart (Cont)

Reference

Symptom

Problem Area

Probable Cause

Action

8. Cont

Power board or logic

HDE signal

Perform printable

9. Missing dots when “\” key is pressed
(always same row) (all printable

board

character test and

observe waveforms

Logic board

MPC

Replace logic board.

Power board

No solenoid drive

Perform printing character

Perform printable character

signals for missing

test and check S1-S7

test, Paragraph 6.1.1.5.

row

at appropriate pin on J6

characters that use the missing

while printing. Check

Tow)

appropriate test points

in drive amplifier for
that row.

No head select signals

Check HS1-HS7 at

for missing row

appropriate points on

power board.

Logic board

No head select signals
for missing row

Check HS1—-HS7 at

Perform printable character

appropriate points on

test, paragraph 6.1.1.5.

logic board.

Failed head select

NOTE

drivers or bad cable
between logic board

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

and power board

output.

Print head

Stuck or broken impact | Power down and up. Retry, | Paragraph 7.3
wire
if condition exists, let it
run. If condition does not

clear, check the following

before replacing head:

Open Solenoid winding | Check winding

(always same row, same letters)

Logic board

Print head cable

Check print head cable

CG ROM

Replace logic board.

Figure 6-66

Paragraph 7.24

6-50

Table 64 Troubleshooting Chart (Cont)
Symptom

10.

Printer stops prior to

Problem Area

Probable Cause

Action

Reference

Printer mechanism

Printer mechanism out

Perform printer mechanism

Chapter 8

of alignment

adjustment procedure.

Servo fuse F1 blown

Check, determine the
following causes before

completing a printed
line

Power board

replacing fuse:

Check, adjust, or replace.

Paragraph 7.7

Check, align, or replace.

Paragraph 7.5

Broken timing belt

Replace.

Paragraph 7.4

Timing belt off pulley

Check and correct. Replace

Paragraph 7.4

Ribbon mechanism

jammed near end of
ribbon

Carriage binding on

poorly adjusted carriage
shafts

belt if worn or frayed.

11.

Printer operates in local but not

Interface or interface

on-line mode.

connectors

Logic board (in current
loop operation)

Connection problem

Check connectors.

Improper jumpers on

Check, correct.

Chapter 2

Failure in isolator

Perform current loop

Paragraph 6.1.2.1

circuits

interface test and check:

current loop converters

S. 1.

Figure 6-60

S. O.

Figure 6-61

TRANSMIT at J3-5.

LINE/LOCAL switch

Switch shorted to

Check, replace.

LOCAL condition
(In EIA operation or
option)

Failure in gating logic

Perform serial line

Paragraph 6.1.2.2

interface test and check:
S. O. at E29-12

Figure 6-63

S. I. 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

Carefully clean off

Paragraph 8-2

disc

encoder disc

Logic board

13. Uneven print density across

Replace logic board.

Chapter 7

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

Repair or replace

Chapter 7

Replace.

Chapter 7

the page.

Printing light in areas

Printing density progressively
drops off to no impressions.

Bad drive clutch
Broken backstop

Spring

Ribbon does not reverse

Print head

Out of adjustment

Check and adjust.

Chapter 7

Ribbon feed does not

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

reverse or feed

Paper jams

Tractors

Paper

6-52

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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-S

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
J1-3 (C16+)
J1-19 (C18-)
R 104 Bottom
R104 Bottom
R 105 Bottom
R105 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.

SOLENOID

w IRES

SOLDERED HERE

SOLENOID ASSOCIATED

WITH PINS

INDICATED (RESISTANCE (@ 2.65 ohms)
RIBBON CABLE
SOLDERED MERE

NUMBER

PIN NUMBER 1

NOTE:

Print head shown on bottom view.
cCP-1T06

Figure 6-66 Print Head Solenoid
Resistance Measurement

6-54

{

3.9k$

CED
oo

—+12V

¥ D69

w10V

$ 6194
+

= C15

T 0.01uf

T gsif

3R92

34870

fl R93

1»4370

=51V >+
L c18
S

L C13

T .Olut

25ut

$R98

36190

- ~12V

- +35V

2 C8

T 190ut

0.22uf T

LM309K

=
CP-13814

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 proceduresin 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
AN
B W=

field environment.

7.2

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

PRINTER HOUSING

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

Printer Housing Removal

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 cabi-

net base (Figure 7-2) and set them aside.

PRINTER

POWER

HOUSING

LOGIC

BOARD

7.2

7.23

BOARD
7.24

TRACTOR
PRINT

RIBBON DRIVE

HEAD

RIBBON DRIVE

ASSEMBLY

DRIVE SHAFTS

PULLEY

7.7

AND TRACTOR

7.10

TRANSFORMER

BAR

ASSEMBLIES

ASSEMBLY

7.17

7.20

7.14

.
TIMING

RIBEON

BELT
7.4

DRIVE FAFNIR
BEARING
7.8

sgfi"“'AGE
na FTS AND
RRIAGE

oH Asgls

MECHANISM
7.13

ASSEMBLY
715

IDLER GEAR

ASSEMBLY

ASSEMBLY
7.18

AND LINE
FUSE HOLDER

RIBBON
ECCENTRIC
WITH CLUTCH

ASSEMBLY
7.5

LINE FILTER

RIBBON

PRINTER

7.9
y

DC MOTOR
AND ENCODER
ASSEMBLY

7.12
.

R':'CBBON SPoOL
AN:? WHEELS
RICTION

DISKS
7.16

7.21

STEPPING
MOTOR
ASSEMBLY

7.19
’

KEYBOARD
ASSEMBLY

7.23
)

CP-3008
CARRIAGE
BUSHINGS
AND CARRIAGE

LEVER
7.6

Figure 7-1

Assembly Removal
Sequence

7-2

2(6-18) S)CREW
{ HIDDEN

S
2 (6-1DE8)N )SCREW
(HID

, PHROIUSNITNEGR

cp-1559

ng Removal

ter Housi
Figure 7-2 Prin

/‘\

J1 CONNECTOR

POWER BOARD

J6 CONNECTOR

M7728

LOGIC BOARD

J2 CONNECTOR

J4 CONNECTOR

J5 CONNECTOR

J3 CONNECTOR

J6 CONNECTOR

J1 CONNECTOR

J4 CONNECTOR

J2 CONNECTOR

ll—fl:'_‘nf‘——'_lcfin

M7723

M7722

LOGIC BOARD

O.‘...“...Q....O...

SOLDER DOTS
TEST POINTS

CP-3012

Figure 7-3

Power Board Connectors

8433-2

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.
7.3.1

Print Head Removal
1.

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

4.6-32)
SCREWS

kep nuts that secure the two ribbon
cable clamps to the cabinet base (Fig-

TIMING BELT AGAINST
CARRIAGE ASSEMBLY

ure 7-5).
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).

PRINT HEAD

Figure 7-4

7-5

Print Head Removal

8433-21

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

CABLE

CLAMP

fo-

ole

g S

9.5" ——ef

r—u

\BOTTOM OF
HEAD
ASSEMBLY

1A S

CABLE
CLAMP
CP- 2255

Figure 7-5

Print Head Cable

Dress the ribbon cable under the dc motor, down through the slot in the rear of the 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.

Close the rear access door on the cabinet.
‘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.

Set the Carriage Adjustment lever to the minimum gap position (detent closest to the print
bar).

6-32 SCREWS TO

"PRINT BAR

PRINT HEAD

0.012

FEELER GAUGE

BE TIGHTENED 10 + 2

IN./LBS. OF TORQUE

CAUTION
ENSURE THAT FEELER GAUGE IS INSERTED
BETWEEN THE PROTRUSIONS ON THE

PRINTHEAD. FAILURE TO DO SOWILL RESULT
IN IMPROPER CLEARANCE AND SHORTEN
THE LIFE OF THE PRINTHEAD.
7393-06

Figure 7-6

Print Head Adjustment

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.
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.
Tighten the four (6-32) screws to 10 £2 in-lb of torque.
Move the print head to the extreme right or left and check for 0.3048 + 0.0508 mm (0.012 £
0.002 inch) clearance.

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).

7.4 TIMING BELT
The following procedure describes the removal and installation of the timing belt.

7.4.1

Timing Belt Removal

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

DRIVE

TIMING BELT

ASSEMBLY

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.

B
_—

SCREW (NOT ON ALL MODELS)

S
Y

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).

LEWND BELT TENSION SPRING

Perform the printer housing installation procedure (Paragraph 7.2).

Figure 7-7

7-9

S
A

—
T

TIMING BELT

——

Belt Tension Spring Location

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

Perform the printer housing removal procedure (Paragraph 7.2.1).

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.

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.

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.

Remove the three (8-32) screws, washers, and standoffs from the front and
rear of the dc motor (Figure 7-8).

Remove the pushrod retaining ring
(Figure 7-14) from the ribbon drive
assembly.

Remove the one (8-32) screw, lockwasher, and flat washer (Figure 7-14)
that secure the ribbon drive assembly
to the upper pivot tab.

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.

CARRIAGE SHAFT MOUNTING
(10-32 ALLEN-CAP SCREWS)

P"'?:S:.:';%TJ?G'SM

0 MOTOR
REAR MOUNT

::oa:lgwgummc HOLES

DC MOTOR

8433-10

NOTE

The nut on top of ribbon drive assembly

Figure 7-8

is loose and can be easily lost.

7-10

Carriage Shaft Screw Access

10.

Mark both ends of each carriage shaft
so that they may be reinstalled in their
original position, if applicable.

11.

Remove the two (10-32) screws, lockwashers, and flat washers connecting
the front of the printer mechanism
(Figure 7-8) 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
5.8 mm (1/8 inch) (Figure 7-9).

REMOVE 4 (10-32) ALLEN CAP

SCREWS FROM CARRIAGE SHAFTS

NOTES

1. Record the location of any carriage
shaft shims observed when removing
the carriage shafts.

14.

PRINT BAR

STIFFNER

1/4-20 HEX-HEAD

SCREW (LOOSEN 1/8IN.)

Figure 7-9

2. The oiler springs are connected to
the end plates and are not part of the
carriage assembly.
13.

SIDE PLATE

Remove the four (10-32) Allen-cap
screws, split lockwashers, and flat
washers from the ends of the two carriage shafts (Figure 7-9).
While

holding

the

carriage

Carriage Shaft Removal

GENTLY TAP
WOODEN OR

ABOVE PRINT

PLASTIC MALLET

BAR

shafts,

gently tap the inside of the right-hand
side plate with a wood or plasic mallet
directly above the print bar (Figure 710). 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 OILERS)
8433-28

Figure 7-10

7-11

Printer Mechanism End Plate
Loosening

7.5.2

Carriage Assembly and Carriage Shaft Installation
1.

Slide both carriage shafts through the carriage assembly.

Slide the carriage shafts through the oilers (Figure 7-10) to the left end plate.
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.
|

Install four (10-32) Allen-cap screws, flat washers, and lockwashers through the end plates
and secure the carriage shafts.
Install the carriage shaft shims (if any) in the location observed during the removal
procedure.

Hand tighten the screws, ensuring that the carriage shafts are seated in the end plates.
Torque the two carriage shafts to 18 £ 2 in-lb.

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).

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-1b.

12.

Loosen the two (10-32) 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:

e 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.

X
J]

AR
>

LEFT HAND

SIDE PLATE ~

N\®

PRI?TBAR
o

! @
0

CREW

10-32

>
Q
A MAXIMUM

DEVIATION ALONG

&‘/7_\/__’___/___—ENTIRE LENGTH OF THE

Figure 7-11

17.

SCREW

)

ROTATE SHAFT TO OBTAIN
ALIGNMENT
TOOL

|_ ALLEN CAP

L@)

RIGHT HAND

/V SIDE PLATE

=il

°|

ALLEN CAP —T7

[

CARRIAGE SHAFTS OF 0.004
(TOTAL INDICATOR

°
—

READING)

CP-3007

Carriage Shaft Parallelism /Alignment

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 pushrod 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, lockwasher, 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

7.6.1

Carriage Bushing and Carriage Lever Removal

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.

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.

CARRIAGE

SHAFTS

ASSEMBLY

PLAIN BUSHING

Figure 7-12

7.6.2

Plain Bushing and Spring Replacement

Carriage Bushing and Carriage Lever Installation
1.

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

7.7 RIBBON DRIVE ASSEMBLY
The following procedure describes the removal and installation of the ribbon drive assembly.

7.7.1

Ribbon Drive Assembly Removal

Perform the printer housing removal procedure (Paragraph 7.2.1).

Remove the ribbon spools and ribbon.

Slip the timing belt off the dc motor puliey.

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, lockwasher, 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.

SPRING

OF PIVOT TAB

RETAINING RING

COMPRESSION

RAISED PORTION

PUSHROD

8-32

BBON CHASSIS ccREw

UPPER PIVOT 90° ANGLE

TAB

CLUTCH

ECCENTRIC

ECCENTRIC 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.

Push the pushrod through the left-hand side plate.

Push the rear of the drive assembly toward the side plate and engage the lower pivot point.

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.
Replace the retaining ring that holds the pushrod in the ribbon chassis.
Insert the compression spring between the left-hand side plate and the ribbon drive.

Replace the timing belt on the ribbon drive pulley and the dc motor pulley.

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.
7.8.1

Ribbon Drive Fafnir Removal
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

PIVOT TAB

8-32 UPPER
PIVOT SCREW N

PUSHROD

RIBBON DRIVE

ELONGATED HOLE

—

.
©

UPPER PIVOT POINT
— |

RIBBON DRIVE PULLEY —|

NOTE:
Travel of pushrod to be equal on both
sides of the elongated hole.

Figure 7-15

Ribbon Drive Adjustment

—

nir 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.

‘
REAR
BEARING

e
BACKSTOP
SPRING

4-40
SET SCREW

8-32
SCREW

FAFNIR
BEARING
7393-3

Figure 7-16

Fafnir Bearing Removal

—
.

RIBBON
DRIVE

SHAFT N

“n‘“

0.29% 0.03 in.l

1.71:302 in. |
FRONT EDGE OF
DRIVE PULLY AND

BE COINCIDENT

COLLAR CLAMP TO

[

]L@J'

R
:

'\x,——l\——\
COLLAR

CLAMP

-O

]

DRIVE
BRACKET

RIBBON

:7/,3{'JHUUU

RIBBON

DRIVE

PULLEY

Figure 7-17

Ribbon Drive Shaft Adjustment

7-19

o
CP-3010

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-Ib of torque. Turn the shaft in a clockwise direction to
ensure freedom of movement.

Replace the ribboh 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.
5.

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.

7.9.1

Ribbon Eccentric with Clutch/Backstop Spring Removal
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.)
6.

7.9.2

Remove the backstop spring from the ribbon eccentric with the clutch (Figure 7-16).
Ribbon Eccentric with Clutch/Backstop Spring Installation

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

Slide the ribbon drive shaft through the rear bearing, eccentric washer, eccentric with 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-l1b of torque. Turn the shaft in a clockwise direction to

clutch retaining tab.

Fafnir bearing, and ribbon drive bracket. (Always turn the shaft in a counterclockwise direction when pushing through the one-way clutch.)

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-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).

7.10 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.

3.
7.10.2

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).
Ribbon Drive Pulley Installation

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 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-lb of
torque.

Slip the timing belt onto the pulleys.

Perform the printer housing installation procedure (Paragraph 7.2.2).

7-21

Select channel 1, set it vertical to C1, and trigger the source to the channel 1.

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.
50% DUTY
CYCLE

MAXIMUM JITTER

I (1.4 DIVISIONS MAXIMUM)

s
ot - y*?" : st4‘.
a...w..,.._wm.
.....................
¥

SCOPEDIVISIONS

§F

7 8

M-0585

Figure 7-20 En;oder 50 Percent Duty Cycle Waveshape
9.

If the channel 1 signal (Figure 7-20)
does not have a 50 percent duty cycle
(itter included), adjust R1 on the
encoder assembly (Figure 7-21).

10.

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.

PHASE ADJUSTMENT SCREWS

7393-5

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 sprmg 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-lb 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-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).

7.10 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.

3.
7.10.2

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).
Ribbon Drive Pulley Installation

Remove the collar clamp from the defective pulley and hand press it onto the new drive
pulley (front edges of the collar gamp 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-lb 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.

RIGHT-HAND

SIDE PLATE

TERMINAL STRIP

Figure 7-18

ENCODER

8433-11

DC Motor/Encoder Cabling
8433-10

DC MOTOR

MOUNTING

Figure 7-19

7-22

DC Motor/Encoder Removal

7.11.2

DC Motor and Encoder Assembly Installation

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-1b.
Thread the dc motor and encoder cables down through the slot at the rear of the cabinet.

Secure the cablesin 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 down cover interlock to perform
adjustment.
Set up the scope as follows:
e
e

Volts/Division: 1 V
Time Division: approximately 20 us

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.
Connect scope CH1 probe to M7722 E6-6, M7723 E2-6, or M7728 E18-6

Connect scope CH2 probe to M7722 E6-8, M7723 E2-8, or M7728 E18-8.
NOTE
The timing belt must be off the dc motor pulley when
performing this procedure.

Carefully remove the encoder’s protective cover. Do not apply any pressure to the disk when
removing the cover.
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 turn 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, CH1
will lead by 90 degrees.

7-23

Select channel 1, set it vertical to C1, and trigger the source to the channel 1.

MAXIMUM JITTER

(1.4 DIVISIONS MAXIMUM)

‘.l
A

ctt

;

]

SRS

)

oodjebefpooofuoscpor

TEE

LRT O

;

SCOPE

DIVISIONS

¢« «

e
ox e

M-0585

Figure 7-20

Encoder 50 Percent Duty Cycle Waveshape

If the channel 1 signal (Figure 7-20)
does not have a 50 percent duty cycle
(itter included), adjust R1 on the
encoder assembly (Figure 7-21).

10.

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.

PHASE ADJUSTMENT SCREWS

7393-5

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 (jitter 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 channel 1 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 R1 and R2.
CAUTION
Exercise extreme caution when adjusting the encoder
to avoid 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

VOLTS/DIV:

VERTICAL MODE:

ALT

TIME/DIV:

60 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,INT, POS

CH1 to:

4V ‘7;—

M7722 EB-6

M7723 E2-6

M7728 E18-6

CH2 to:

GNDJL

M7722 EG-8

M7723 E2-8

M7728 E18-8

M-0724

Figure 7-22

Encoder Phasing Adjustment

7-25

7.12 PRINTER MECHANISM ASSEMBLY
The following procedure describes the removal and installation of the printer mechanism assembly.
7.12.1

Printer Mechanism Assembly Removal
1.

Perform the printer housing removal procedure (Paragraph 7.2.1).

Remove the ribbon spools and ribbon.

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.
Open the rear access door.
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.

If applicable, remove the top of form
assembly.
Remove the 6-32 screw, fastening
ground wire to the cabinet base (Figure 7-23).
GROUND
WIRE

Remove the speaker wires.

PRINTER
MECHANISM

PRINTER MECHANISM
MOUNT (ONE AT
EACH CORNER)
8433-14

Remove the 4-40 screw and nut from
the terminal strip (Figure 7-18).
10.

Figure 7-23 Printer Mechanism
Removal Preparation

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.

11.

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.

8433-15

LIFT UP AND REMOVE

Figure 7-24
7-26

Printer Mechanism Removal

7.12.2

Printer Mechanism Installation

Remove the ground wire from the old printer mechanism and connect it to the new printer
mechanism.

Slide the carriage assembly to the left side of the printer mechanism.
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.
Secure the printer mechanism with four (10-32) screws, lockwashers, and flat washers. Make
the screws finger tight.

If applicable, secure the top of form assembly to new pfinter mechanism.
Thread the cables and wires down through the slots at the rear of the cabinet.

Secure the stepping motor wires in the cable clamp. Reconnect the connector to J5 on the
power board.

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.

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

PRINTER

PRINTBAR

MECHANISM

® @l

10-32 SCREW

]

v -

}—
®

HOLE

—

——

A
o+

O = ®

FRONT FACE OF PRINTBAR
COINCIDENT WITH C/L OF
REFERENCE HOLE

10-32 SCREW
CP-3009

Figure 7-25

15.

16.

17.

Printer Mechanism Alignment

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

0.030

ASSEMBLY AND BENT-UP FLANGE

FEELER GAUGE

BENT-UP
FLANGE

CARRIAGE
ASSEMBLY B

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

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.

Drive Shaft and Tractor
7.13.1 Tractor al
Assembly Remov

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.

TRACTOR SHAFTS
o

TRACTOR

RETAINING RINGS

Figure 7-27

7.13.2

7937-37

Tractor Removal

Tractor Drive Shaft and Tractor Assembly Installation

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 flat 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 flat.

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).

INDEX
MARK
'

g\g

LEFT-HAND

SIDE PLATE

ALTERNATE

TRACTOR

[—2-1/8 IN.
INDEX

MARK ~——

TRACTOR _H1]

BUSHING

TRACTOR
FEED PIN

RIGHT HAND _—T

TRACTOR

7393-14

TRACTOR

PHASING
cp-225

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
1.

Ribbon Chassis Assembly Removal

Perform the printer housing removal
procedure (Paragraph 7.2.1).
Remove
ribbon.

the

ribbon

spools

8-32

SCREW

and

RETAINING

8-32

RING

SCREWS

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).

6-32

NOTE

SCREWS

A cover interlock switch is connected to

the ribbon chassis on late model

Figure 7-29

printers.

642

RIBBON

CHASSIS
.

SCREWS

7393.3

Ribbon Chassis Removal

Remove the speaker leads.

Remove the ribbon chassis and set it
aside.
Ribbon Chassis Assembly Installation
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 1b) (Figure 7-30).
Perform the printer housing installation procedure (Paragraph 7.2.2).
7-31

RIBBON

IDLER

RIBBON

PRINTHEAD

)

_],

RIBBON

SPOOL

—

! e— |

c—

|—

e
==

o
-

—

=~ a2

LBS

f“ THAN 4.0

‘=

PULL

RIBBON
IDLER

RIBBON
IDLER
CP-3145

Figure 7-30

7.15

Ribbon Threading/Drag Test

RIBBON SPOOL RATCHET WHEELS AND FRICTION 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.

BACKSTOP
SPRING

RIBBON DRIVE
SHAFT

ECCENTRIC

(

—

SPOOL DRIVER

(LOCATED ON TOP)
COMPRESSION SPRING
AND WASHER
FRICTION
DISKS

PUSH

ROD
MAIN
PAWL

REVERSE

RATCHET WHEEL

SENSOR

ADJUSTING SCREW
AND NUT

INTERPOSER

BAIL CAMMING
FOLLOWERS

WASHER

INTERPOSER

PAWL

cP-1707

Figure 7-31

7.15.2

Friction Disk/Ratchet Wheel Replacement

Ribbon Spool Ratchet Wheel(s) and Friction Disk Installation

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

Perform the ribbon chassis assembly installation procedure (Paragraph 7.14.2).

spool in the ribbon chassis.

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 Removal
1.

Perform the printer housing removal procedure (Paragraph 7.2.1).

Remove the ribbon spools and ribbon.

Slip the belt off the dc motor pulley.
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).
Move the carriage assembly all the way to the left.
NOTE
Observe the location of any shims between the carriage bars and the left-hand end plate.

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
SIDE PLATE AND
SenTLY
LIF UP
PRINT BAR)

(SPREAD THE LEFT-HAND

LEFT-HAND SIDE PLATE

Remove the two (8-32) screws, lockwashers, and flat washers connecting
the ribbon chassis to the print bar.

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).
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 7-

Gently

SCREW LOCATION

HOLE (1/-20 HEX-HEAD

32)'
11.

CARRIAGE BAR

PRINT BAR MOUNTING
SCREW)

spread

the right-hand side

Figure 7-32

plate and remove the print bar.

7-34

Print Bar Removal

7937-29

7.16.2

Print Bar Installatien
1.

CALIBRATE
BLOCK

Carefully slide the new print bar
into position and insert the carriage
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

GAUGE

ZEROED

GAUGE

chassis).

Reinstall the carriage shaft shims, if
applicable, and secure the carriage
shafts with two (10-32) Allen-cap
screws, lockwashers, and flat wash-

7937-31

ers. Torque the screws to 18 £ 2 inIb.

Figure 7-33 Calibrate Alignment
Gauge and Block

Calibrate the alignment gauge by setting the dial to zero with the calibrate block screwed
securely in place (Figure 7-33).

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.

Secure the ends of the print bar with two (1/4-20) hex-head screws, lockwashers, and flat

washers. Hand tighten the screws.

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.

Slide the gauge across the full length of the carriage shafts. The total indicator reading must
not vary more than 0.004.

Torque the print bar with 7/16 hex-head nuts to 75 + 5 in-lb.
10.

Secure the ribbon chassis to the print bar with two (8-32) screws, lockwashers, and flat
~ washers. Torque the screws to 18 + 2 in-Ib.

11.

Install the 10-32 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

1/4-20 PRINT
BAR SCREW

RIGHT

BAR

DC MOTOR

7937-8

SIDE OF
CARRIAGE
SHAFTS

+0.0005 *0-001 +0.0015
-0.0005
-0.001

GAUGE MUST INDICATE 0.004 (TOTAL INDICATOR READING)
ACROSS PRINT BAR WITH THE TWO END READINGS BEING

EQUAL WITHIN 0.00156
-0.0015

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.
7.17.1

IDLER GEAR
ASSEMBLY

8-32

LINE FEED

SCREW

KNOB

Idler Gear Assembly Removal

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

LEFT-HAND

1dler Gear Assembly Installation

SIDE PLATE

0.002 - 0.007 IN.

6-32

SCREW

BACKLASH AND EQUAL

Secure the new idler gear assembly to
the left-hand side plate with the two
(8-32) screws, lockwashers, and flat

DEPTH PENETRATION
7393-1n

Figure 7-35

washers. Make the screws finger tight.

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-lb 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

Perform the printer housing remov-

STEPPING MOTOR (8-32) SCREWS

al 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 J5 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

(8-32) SCREWS

washers, lockwashers, and hex nuts
that secure the stepping motor to

the left-hand side plate. Set the

Figure 7-36

stepping motor aside (Figure 7-36).

7.18.2
1.

7393-3

Stepping Motor Removal

Stepping Motor Assembly Installation

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 lockwashers 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-1b 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 (Para-

graph 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

Remove the ac plug from the outlet box.

Perform printer housing removal procedure (Paragraph 7.2.1).

Open the rear access door on the cabinet.
WARNING
Power must be removed from the LA36 prior to performing this procedure.

Disconnect the connector from J3 on the power board (Figure 7-37).
NOTE
Steps S and 6 are only applicable to some printers.

MATE-N-LOK

CONNECTOR
J3

116V -230V

JUMPER (J1)

FUSE MTG
BRACKET

TRANSFORMER (T1)

8-32
SCREW

8-32

SCREW

7393a.

Figure 7-37

Early LA36 Printer

Transformer Removal (Sheet 1 of 2)
7-39

TRANSFORMER
'MOUNTING

TRANSFORMER
’

SCREWS

(1 OF 3)
8-32

Figure 7-37

Current LA36 Printer

Transformer Removal (Sheet 2 of 2)

7-40

8433-7

Remove the two (8-32) screws and lockwashers that secure the fuse mounting bracket to the
cabinet (Figure 7-37).

Remove the green jumper wire from capacitor C5 (Figure 7-38).

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.

Remove the four (8-32) screws, lockwashers, and flat washers that secure the keyboard bezel
to the cabinet base (Figure 7-9).

CAPACITOR C5

GREEN JUMPER

FUSE (F1)

WIRE

FUSE MTG

BRACKET

7393-7

Figure 7-38

Capacitor C5

7-41

Turn the keyboard upside down and remove the quick-disconnect (Figure 7-39) from the
POWER switch (S1).

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 (S1) 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).

POWER

LKO02

SWITCH (81)

KEYBOARD

§§

REMOVE

THESE TWO

CONNECTORS

Figure 7-39

Early Version

Rocker Switch S1 (Sheet 1 of 2)

7-42

*
*®

b
]

POWER SWITCH (81)

Figure 7-39

8433-16

Current Version

Rocker Switch S1 (Sheet 2 of 2)

Transformer Assembly Installation Procedure

7.19.2

1. Place the new transformer in the cabinet and secure with the three or four (8-32) screws,
lockwashers, 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-1b of torque.
2.

Reconnect the Mate-N-Lok to the fan assembly.

Pull the wires up through the slot in the rear of the cabinet and reconnect the quick-

disconnects to the power switch on the keyboard.

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.

S. Dress the wires and cables from the keyboard to the transformer and secure with cable ties.
6.

Reconnect the connector to J3 on the power board.

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

Replace the green jumper wire on capacitor CS.

Secure the fuse mounting bracket to the cabinet with the two (8-32) screws and lockwashers.

10.

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.

Remove the LA36 ac plug from the ac outlet.

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 F1 prior to performing the next step.

Disconnect all external wires that connect to capacitor C5 and fuse F1 (Figure 7-38).

Remove the fuse mounting bracket and set aside.

p—

Type 1 Line Filter and Fuse Holder Installation
[)

7.20.2

Install the new line filter or fuse holder in the fuse mounting.

Reconnect all external wires to capacitor C5 and fuse F1 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

POWER

7.20.3 Type 2 Line Filter and Fuse Holder
Removal
1.

FILTER ASSEMBLY

(COVER REMOVED)

BOARD

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
7.20.4

8433-6

Type 2 Filter Assembly Removal

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 LKO02, LKO3 KEYBOARD ASSEMBLY AND FRONT PANEL ASSEMBLY
The following procedure describes- the removal and installation of the LK02, LKO03 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.

® —-40

‘a

y©
2 (8-32)
SCREWS

2 (8-32)
SCREWS

ZZKEYBOARD BEZEL
CP-1558

Figure 7-41

7.21.2

Keyboard Bezel Removal

LKO02 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 phnel (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

HEX

STANDOFFS

LKO2

KEYBOARD

8-32 KEP NUTS

CONNECTOR

CP-1567

Figure 7 -42

LKO02 Keyboard Removal

7-47

KEYBOARD

BEZEL

HEX STANDOFF

LKO3 KEYBOARD
CONNECTOR

8-32 KEP

NUT

CP-1566

Figure 7-43

LKO03 Keyboard Removal

7-48

INSULATOR
WASHER

}

TO EXTENDER BOARD
(IF APPLICABLE)

RED

STRIPE

-— 9
cCP-2103

Figure 7-44

LKO03 Keyboard and Control Pad Removal

7-49

7.22 POWER BOARD
The following procedure describes the removal and installation of the power board.
7.22.1

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, lockwashers, 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.

7.22.2

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 + 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.

8.2 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).

Set up the scope as follows:
*
e

Volts/Division: 1 V
Time Division: approximately 50 us

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.

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).
Connect scope CHI1 probe to E6-6 on the M7722 logic board (E2-6 on M7723, E18-6 on
M7728).

Connect scope CH2 probe to E6-8 on the M7722 logic board (E2-8 on M7723, E18-8 on
M7728).

Slip the timing belt off the dc motor pulley.

Restore power to the LA 36 (set the POWER switch to ON). The motor will rotate clockwise
as viewed from the front.
Select channel 1, set vertical to CH1, and trigger source to channel 1.

Adjust scope for one duty cycle full scale (Figure 8-1). Observe the duty cycle.

50% DUTY
CYCLE

MAXIMUM JITTER

(1.4 DIVISIONS MAXIMUM)

SCOPEDIVISIONS

1 2

10
M-0585

Figure 8-1

Encoder 50 Percent Duty Cycle Wave Shape

8-2

10.

If the channel 1 signal (Figure 8-1)
does not have a” 50 percent duty

cycle

(jitter

included),

PHASE ADJUSTMENT SCREWS

carefully

remove the encoder cover and
adjust R1 on the encoder assembly
(Figure 7-2).
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

13.

Adjust the scope for one duty cycle
full scale (Figure 8-1). Observe the
duty cycle.
R1

14.

If the channel 2 signal (Figure 8-1)
does not have a 50 percent duty
cycle (jitter included), adjust R2 on

7393-5

Figure 8-2 Encoder (Rear View)

the encoder assembly (Figure 8-2).

15.

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 +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 dc motor pulley.

23.

Perform the printer housing installation procedure (Paragraph 7.2.2).

8-3

SCOPE SETUP

VOLTS/DIV:

VERTICAL MODE:

ALT

TIME/DIV:

60 us

TRIG MODE:

NORMAL

TRIG SOURCE:

CH1,AC,INT, POS

CH1 to:

M7722 E6-6
M7723 E2-6

M7728 E18-6

CH2 to:

M7722 EG-8
M7723 E2-8

M7728 E18-8

M-0724

Figure 8-3

Encoder Phasing Waveshape

8.3 PRINT HEAD ADJUSTMENT
The followmg procedure describes the print head adjustment. Having the print head out of adjustment
will resultin poor print quality and shortened head life.

Set the POWER switch to OFF.

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.

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.

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.

6-32 SCREWS TO

PRINT BAR

PRINT HEAD

0.012

FEELER GAUGE

BE TIGHTENED 10 + 2

IN./LBS. OF TORQUE

CAUTION

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

Figure 8-4

Print Head Adjustment

Move the print head to extreme right or left and check for 0.3048 + 0.0508 mm (0.012 +
0.002 inch) clearance.
NOTE
If the head is aligned properly do not perform the
following steps. Restore the L.A36 to its normal operating configuration.

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.
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.

Tighten the four (6-32) screws to 10 + 2 in-lb of torque.
Move the print head to the extreme right or left and check for 0.3048 + 0.0508 mm (0.012 +
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 SHAFT 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.

Perform the printer housing removal procedure (Paragraph 7.2.1).

Remove the ribbon and ribbon spools.

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 (6-32)
SCREWS

—T
]

)

PUSH

TO RELIEVE

BELT TENSION

RIBBON DRIVE
"
PULLEY

—

o |

\\DC MOTOR

PULLEY

=
BlG 8 nn
8 g =
=
e
=
=
tH

\\K\

o oo Dele - T 0 Jo fr e 0 B B

TIMING

BELT

DT0D0EEI0NnIN
00 aIn o
200000000
SR

PRINTHEAD—/

CP-1560

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.

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 L.A36 to its
normal operating configuration.

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

AL
=

LEFT HAND

SIDE PLATE ~—|_

©)
|

°|

_ ALLEN CAP

—

10-32

’

ALLEN CAP —1
SCREW

RIGHT HAND

SIDE PLATE

ROTATE SHAFT TO OBTAIN
A MAXIMUM

DEVIATION ALONG

@/___74_______,__,&1:% LENGTH OF THE

%'O?_NMENT

SCREW

CARRIAGE SHAFTS OF 0.004

—

(TOTAL INDICATOR READING)
CP-3007

Figure 8-6

Carriage Shaft Parallelism /Alignment

Slide the alignment gauge along the total length of the carriage shafts.

e 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.

Torque the front carriage shaft to 18 £ 2 in-lb 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

8.5 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

Set the POWER switch to OFF.

Perform the printer housing removal procedure (Paragraph 7.2.1).

GAUGE
ZEROED

GAUGE

Remove the ribbon and ribbon

spools.

Calibrate the alignment gauge by
setting the dial to zero with the calibrate b!ock screwed securely in

7937-31

Figure 8-7

place (Figure 8-7).

Alignment Gauge

and Calibration Block

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.

Repeat the above step with the gauge on the extreme left ofA 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.

Loosen the two hex-heaad (1/4-20) 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).

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.
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-1b.

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

1/4-20 PRINT
BAR SCREW

7937-8

PRINT
BAR

RIGHT

DC MOTOR

SIDE OF
CARRIAGE

SHAFTS

+0.0005 +0:001 +0.0015
GAUGE MUST INDICATE 0.004 (TOTAL INDICATOR READING)
ACROSS PRINT BAR WITH THE TWO END READINGS BEING

-0.001

EQUAL WITHIN 0.0015

-0.0015

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-1b of torque.

10-32

SCREW

|c)

“3\

o
10-32 SCREW

Figure 8-9

HOLE

FRONT FACE OF PRINTBAR
REFERENCE

ono

REFERENCE

o4—= COINCIDENT WITH C/L OF

———

[o}

10-32 SCREW

]

—

MECHANISM

® @l

—

PRINTER

PRINTBAR

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

0.030

ASSEMBLY AND BENT-UP FLANGE

FEELER GAUGE
PAPER GUIDE

BENT-UP
FLANGE

CARRIAGE
ASSEMBLY

BENT-UP FLANGE

(PART OF BASE)

7393-13

Figure 8-10

ADJUST FOR 0.10 TO 0.14 INCH GAP
BETWEEN PAPER GUIDE AND BENT-UP
FLANGE (FLANGE IS PART OF BASE)

Printer Mechanism

Figure 8-11

Adjustment

8-12

Paper Guide Adjustment

7937-13

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 t0

reform the switch arm to attain the

adjustment.

ARM TO BE FLUSH

a7 Snp ¥ BANSFER

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).

Replace the printer cover.

Restore power.

(O PAPER OUT
SWITCH
7412424

\ L
cp-2249

Tighten the two (4-40) screwsto 5+ 1
in-1b.

\\\\\\\\\\\\\\\\\\\\\\\\\\\\‘ | \—‘.\\\\\\\\‘

8.7 PAPER OUT SWITCH ADJUSTMENT
This procedure describes the PAPER OUT
switch adjustment.

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.

Lift up and remove the printer cover.

Remove the ribbon spools and ribbon.
Place an empty spool on the side not being driven.
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.

Adjust the spool drag by tightening or loosening the adjustment screw, while holding the nut
at the base of the screw. An 11/32-inch wrench is required to hold the nut. |
|

Move the direction changing guide and check the remaining undriven spool for 113.4 to
170.1 g (4 to 6 oz) of tension.
Install the ribbon and spools.

8-13

PULL

4 TO Soz

NOTE:

Perform this test
one side ot a time
ADJUSTMENT
SCREW

"CHANGING
GuIDE |O]

’

N©

°
(¢

LEFT

SPOOL

‘

)

=
@

O
.

[

—

L N———

0O
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 1b) (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 1b) 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

PRINTHEAD

RIBBON

SPOOL

RIBBON

SPOOL

IDLER

()|

—

NO MORE

.'. THAN 3.5

=—7

_—

LBS PULL

[

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.

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-lb, and repeat step 4.

Replace the cover on the printer.

Restore power to the LA36.

CENTERLINE OF

PIVOT

ELONGATED HOLE

TAB

SCREWW\

PUSHROD

8-32 UPPER
PIVOT

RIBBON DRIVE

-1

n lL
:

PIVOT ! |

UPPER | O
POINT

©)

RIBBON

DRIVE —
PULLEY

[“

:
\

"(@J .

—

0
Wl@)

’

NOTE:

Travel of pushrod to be equal on both
sides of the elongated hole.
CP-3143

Figure 8-15

Ribbon Drive Adjustment
8-16

SPRING

OF PIVOT TAB

RETAINING RING

RIBBON CHASS|s

COMPRESSION

RAISED PORTION

PUSHROD

8-32

SCREW

UPPER PIVOT

TAB

90° ANGLE

CLUTCH

ECCENTRIC

TAB

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).

IDLER GEAR

ASSEMBLY

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.

LEFT.HAND

SIDE PLATE

Tighten the two (8-32) screws to 18 +
2 in-1b of torque.

8-32

LINE FEED

SCREW

KNOB

0002-0007IN. ~~

6-32

SCREW

DEPTH PENETRATION
7393-10

Perform the printer housing installa-

Figure 8-17 Idler Gear Assembly

tion procedure (Paragraph 7.2.2).

Restore power to the LA36.

*Backlash is the amount a gear turns prior to turning the gear it meshes with.

8-18

8.1

BUMPER ASSEMBLY ADJUSTMENT

Tighten the screws (Figure §-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.

)

—

\>° | '_._
—

‘— it

<+—1.67 in.

—

(42.42 mm)

<+— 1.67in.

(42.42mm)
CP-3144

Figure 8-18

Bumper Assembly Adjustment

8-19

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)

SAE 30

1 or 2 drops in
each of the five
places shown in
Figure 8-19

LEFT-HAND ___
SIDE PLATE

OlL BACK
BEARING
OIL ON
WASHER
OIL BETWEEN
ROD END AND
ECCENTRIC COIL

OIL BACKSTOP
BEARING
OIL CLUTCH

ADD 1 OR 2 DROPS
OF DECA49-01174

OR NYE OiL 622
TO EACH OILER

7135-12
7937-35

Figure 8-19 Carriage Shaft

Figure 8-20

Lubrication

8-20

Ribbon Drive Assembly
Lubrication

APPENDIX A

ENGINEERING DRAWINGS

A-1

This Growing and spasiSestions, hesein, are the prop

e TR

witien EOrmIsen.

;

s A

COPVYRIGHT
© 1974, DIGITAL

Pr
COMASSV.lL_G_A_IQAl

|| ares
ovT
Su.

2. POWER CORD COLORS ARE AS FOLLOWS:——
,

VOLTAGE |

115 V

e3ov

GND _| GREEN
(NEUTRA
JWHITE

_|GRN/YEL
BLUE

HOT

BLACHK

KBY BOARD
MM

oal

LkP>

Y\
ol

MECHAN I SM

| BROWN

VIS

PR\ RN P

X 2

|
C

PRINT MERD

B8DD

—

7005883

—

—
‘

{——PRINT SOLENOIos—-l

" carrince

(OB "@'\
G
Dl
R B TM
Dl B gl B Bl 5 Bl B |

SFFT

RED

| MOTOR

Pm. DC.

7 ASE

+21vV

/I 39678 //121631192927333435
/5

\E{HTTTTTTTI YYY

GND

E tsv

GND @

@ csy

2 117

2 vE
2 K2
— \-’ZJ

6 3 5

RED/YEL

RED

—

GAND

’

war?1]

Koé

POWE R

SWITCH

BLk

115w

]

SPEAKER

Ly
-1t

e UF

8LU

8LU/BLk

8LU

)

'n (g
|

BLU/BLK

WHT

OBARN

*
REF DESIGNATION
'

ary

/JL7

:
[

BRN

fle

n‘f%
.6 3

AANAAAN

2y P

[

sichoomorey

Qlo] | RG]

48 3 fl g

AAN

v/0

212 ST
al |5hy|5

i
§

+5v

310

8
L3

(2) 1900@ UF

18ODOUF

POWER XFMR

&8'52 %Ly

58/68 He

L_:.{(._*_

7, SEE NOTE %3

FAN

STEPPER MOTOR

S s
&

7 8

230V COWNECTION ONLY

LF2

—
L

LINE FEED

Y? - *z Y
(W4RED]|VE

jwar_2

]/
i|

UTRAL

<
< 5

Jé

1185 CONNECTION ONLY

|\ 3

POWER BOARD
54,0805

+21v

175/290v

-12V

E ;,zz L

3. —

LFI

5 ¢

70 DF 11
IF USED

? M2
2 bE

+21V

k8S/

+Sv
6ND

- R2

+2IV

RED /

12V

5¢
/ &

S s2

> 7

N
"\
encooer g—aeo sink | J>4o

J4e iy
BOARD
L 0GIC
3_’6_"!8

—_—— e

G6RN

BASE

MUST BE REPLACED BY 50 HZ XFMR
1612521.

3. FOR 50 HZ.OPERATION TRANSFORMER

| (9T 52T e|

OFPTIO

1.5A S8 FOR 230 V

EQUIPMENT COR PORATION

[’—__J

NOTES:
1.FUSE F1 1S 3A SB FOR 115V AND

Carporation and shel net be

‘

\ A

szf\(pu“
. =~ ‘,;..u < ?J

.-.m;l

PARTS LIST

ORI

]
J I

NE KRB 2|2
MR°INIZ
NREHE2
<

DESCRIPTION

]

NEXT HIGHER ASS

SEMICONDUCTOR CONVERSION CHART
3

ower| oF /

PART NO. E
EQUIPMENTY

SRS SR onAT IO

LAS6
POWER SCHEMATIC
NUMBER
I m'.
wr ] 1T 1 1.1 1 1 1 [

A-3

1
NOTES:

fi?:u%fivg- D

. ALL

:wumm%w\-‘:

HARDWARE

COPvamert © |4 3ep SUSTAL SUIH
COn0ORA

<EE NOTE *2

—

‘

}

MOUNT

ITEM

;

INSERTING

TABLE TOP (REF)

THE

COVER

e1
,

THE

BENT

“PAPER

HOLES

ENDS

BASKET" INTO

PROVIDED

SHOWN.

—

{

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REF | ENGINEERING

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FINISH
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FIRST USED ON OPTION/MODEL | qryv,

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UNLESS OTHERWISE SPECIFIED

SHOWN

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212 |£3.£8
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DEC NO.

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___{NEXT HIGHER ASSY

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REE

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[ 1T I
ri1 11
1
DATE
EQUIPMENT
POIRIER
| 2574 mnana MAYNARD
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PART NO.

DESCRIPTION

REF DESIGNATION

ETCH BOARDREV | F |

Rol & R DNxSl
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3

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DEC NO.

EIA NO.

SEMICONDUCTOR CONVERSION CHART
3
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7 OF 2

NUMBER

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NUMBER

SIZE|CODE

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LKOe FE (BOARD

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300213218

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Lz
O_EZ“ ngoq

o
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0320”—0

24 y

1 4

L 2 1 v 1 "
4
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O—Eozs—o o 3,2 028
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06
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YIGWNN

~- /00y — *#25V
13 IN C'AAs’Locx—-i

v
HH

I
50/

‘/.\.3_87

PROPERTY OF DIGITAL EQUIPMENT

| [Z]-05520%5 FJq] 2 |

]

~1/V 70-/3V

D|CS|5410726— D

oF ¢

oist. |

[

]

o uaeawn whote or i part a3
This drawing and sped:!.cations. herein. are t::e pro:e

P.2.°Pfdg2 |
NOTES:

the basis for *he manufacture or sale of items without
written

permission

COPYRGHT ©

1974, DIGITAL

EQUIPMENT CORPORATION

THRU

4N HOLES

cO2.0 —o{t=

S
7

4.531

S5.00

— L

REF

)

500 REF | = /.438+J
REF
, 2.944 REF—

—

25 REF

OIS

aim

2’
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e |

1. 085
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s
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=, 4O6

A-SP-\KJ2 -¢-2|

ASPLKP2-@F-1|

|KEYC AP SET (CURSHE ZET €)|a00H4STO- T4

REF |TEEST

SPeC

REF |ENGINEERING
i

[ KEYSWITCH ARRAY ¢ MODULH D-CS-5410819-0-1f

I
, FIRST USED ON OPTION/MODEL

[ DATE

EQUIPMENT

NEXT HIGHER ASSY.

MATERIAL

s =15

o:z2| |%

DRI) 100-A

PARTS LIST

I KEY
DATE
PE?‘_E:.NG,
>
-i] n'] .‘.'. Z)A'}EM
ASSY
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SHARP
BREAK
AND
BURRS
REMOVE
P;,,/‘-,y
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CORNERS SURFACE QUALITY

wl|oz
HE:é Zo

FINISH
—

'LEOM

mnannan CORPORATION
6-3“7¢
IN INCHES W
g?meusvoru
TOLERANCES
CHK'D / i4
DAT TITLE
MAYNARD MASSACHUSETTS
7/’2
fi
AL
ANGLES
DECIMALS
A
XXX 1‘075 +0° 30" 52‘6’,/;, ~ e %ZZ?[

o
1
A

DfC FORM

PART NO

DESCRIPTION

Qry.

LK®3
UNLESS OTHE RWISE SPECIFIED | DRN.

gl_1°

SPEC

NUMBER
SIZEJCODE
B-DD-LK@3@~
D|UA|LK@34
D-LKP3SCALE A/
ost] 1T 1 1 I 1 [ |
_ / OF
SHEET
2

[

A-43

REV.

“THIS DRAWING AND SPECIFICATIONS,

ARE THE

HEREIN,

| [8]r0-6801p5[5Iq] 2 |

REE

X-Y COORDINATE HOLE LOCATION

|K-CO-5410819-0-4

e e o sesacoucto on comeoon o mwroe | INOTES:

REF

ASSY/DRILLING HOLE LOCATION |D-AH-5410819-0-5| 2

CorvRiGHT@)1 574" DIGITAL EQUIPMENT CORPORATION"

REF

MODULE Eco HISTORY

8-mw-5410819-0-6| 3

ETCHED

sS5o/c818

oo 74

1210025

OR IN PART AS THE BASIS FOR THE MANUFACTURE OR SALE

. ALL DIODES ARE 0664,

1/}

01 THRU

J8F DI,
W2 DRILL

DIODES

D o4

SOCKET

(16 PIAS)

Il KEYSWITCH.

D-AD-7009891-0-0 | 7

ARRAY

_—

HOLE
/1o —or

o+ PLACES

Jl
/

D1/

CIRCUIT BOARD

}

]

*2::::8::‘1&
X2

(1]
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3.00

KEY SWITCH

RLRPARY

awit

/9 il

09
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578

D4
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[=]

(2]

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4.53/

5.00

400

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094 — p——— 2. 25

KEY SWITCH

—{, 500

AORRY
/438

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DIMENSIONS

Y A
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44—

- Y5
4 >

FOR REFERENCE ONLY
Y6

QTY

LA 36

PARTS LIST

ETCH BOARDREV | B |

MRREEE
a

GND | + 5v

IC PIN LOCATIONS

OEC FORM NO

[+ 4

DEC NO.

EIA NO.

DEC NO.

EIA_NO.

SEMICONDUCTOR CONVERSION CHART

A-44

SCALE -

SHEET

[

Titfa]1] 050 0n502

DATE

NEXT HIGHER ASSY

1-4-14 | TiTLE

Yer.

DATE

INESIE ¥

I 1

DATE

ENG.

I ol_12l¥

w(l o4°

RESPECTIVELY EXCEPTIONS ARE STATED ABOVE

z|(|O{%] %

|z x\a-u

GND AND SV ARE USUALLY PIN 7 AND 14

DRN.

o Ske(g| 2

IC TYPE

PART NO.

DESCRIPTION

REF DESIGNATION

FIRST USED ON OPTION MODEL

e,y

SITE
|

[

KEYSWITCH

ARRAY MODULE

NUMBER

DICS]|5410819-0-1
osr. |

]

| [

[ JT T

l RV,

4
“THIS DRAWING AND SPECIFICATIONS, HEREIN, ARE THE
PROPERTY OF DIGITAL EQUIPMENT CORPORATION AND:
SHALL NOT BE REPRODUCED OR COPIED OR USED IN WHOLE
OR IN PART AS THE BASIS FOR THE MANUFACTURE OR SALE
OF ITEMS WI HOU;g«amm PERMISSION.

'SR

| SOLVENT WELD ENTEK KEY TO iTC KEY CAP
ADAPTER WITH IP3 " WELD ON"AT VENDOR'S

SPTINN.

AR’

PLASTIC DIPE CEMENT

MANGEACTURED

NO 772 FOR

BY: INDUZTRIAL

POLYCHEMITAL SERVICE BOX 47|

D
7

90247

|—

GARDENA, CALIFORNIA

—

——————— E ENTER
)

7;
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070

[€&—

¥
<
% '

—| .45 5 —

‘o

2r)

2960
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~—1.520 —=

REF

REF[TEST SPEC

A-SP-LKO2-@-2|

|53

REF |[ENGINEERING SPEC

A-SP-LKOz-9-1 | 3

|[KEYCAP

SET

D-PS5-1212287-74

|_|AKEYSWITCHARRAY MoD.|D-C5-5416358-7]
FIRST USED ON OPTION/MODEL

.—1

arv.

DESCRIPTION

DATE

LFrO3-A

a <

DIMENSIONS ARE W—W

UNLESS OTHERWISE SPECIFIED

12 \.\ - g

ILLIMETER

g § <EEE
S

E § (;) 3 'E’ l

THIRD ANGLE

:[)

]

\Q»?g

-t

PROJECTION

-Jl

INCHES

ANGLES
|

PRODx

CORNERS SURFACE QUALITY v~

2’7fl’= . 7/}DAT; )]
e,

.'~

pas

765{’

|NEXT HIGHER ASSY.

|d| l I | I |t|a| I |

7%,2{&/ TITLE

REMOVE BURRS AND BREAKSHAEF— %Jj Z
X

PARTS LIST

CHK’'D

?{;,7 E/I:z;u,

MATERIAL

&“

FINISH

[

]

SCALE

1/l

’

SHEET

[

]

| | B

'TEM

KEY

KE YBO ARD ASSY

@ =3 | SEE PARTS LIST [FAD7009750-0-0 CJUA LKO3-A-2

HARE

oo hos

DIMENSIONAL TOLERANCE

PART NO.

ISIZE|CODE

ost.

]

NUMBER

[

REV,

]

A-45

| NOTES:7
8
e ——

. :WITH W1 INSERTED, LED DS WILL

HE MANEACTURE O SALE OF —
A EAS FOR Ts
PRT

1
] 2|
[ [Z]0-2X-Y2lms
COORDINATE HOLE LOCATIONK-CO-54117270-4] |

3 IREN

-0-5] 2
LING HOLE LAYOUT JD-AH-6411727
ASSY/DRIL
-54(1727-0-6| 3
MODULE ECO HISTORY

REFF|

ETCHED CIRCUVIT BOARD

{

ALWAYS BE ILLUMINATED

S | RI-RS

2. W1 MUST BE REMOVED WHEN

ETCH REVA

2 |JIA,JIB

APL

3. THERE 1S NO PROVISION FOR W1 ON

4. APPLY ITEM 15 BETWEEN ITEMS 10£13

C-MD-7414073-00 8

I |St-S4

KEYSWITCH, 4 LOCKING

C-AD-7011188-0-0| 10

KEYSWITCH,3 LOCKING

C-AD-701152600(13

CEMENT, PERMA BOND

9009157

FASTON TAR

SEENOTE
4

SCR, PPH THD CUT *4-40x5/LG|

|s5-s¢

WIRE, INSULATED \)UMPER(A LG}

|
8

3.500

9002185-00014

Runiie

HDX.”

wo®

FDX

LOC.

|
|

300",

D R
|

309
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etNN

LlNEl

w|(5EE NOTES)

Je | be

Ed
2s
RI
300
4T
AN
5 m—
SO
7 »——@4\/\/\/\2%@—-

1
o0 R3o RZa0Rl QK 835
+ ®Soo
Wi R4
* | .350
f
\H\
- .
2.98
~—2.148—
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4 HOLES

3000 ———o4

3.000

,‘a

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AUTO

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B

8 B
ALL

[I|

14 B>

38 .625

| 588 — et
e

2009236-1

1.500

—

/
7

MOMENTARY

/ SWITCH (S8)

2007112-00] o

lokcslsanz27-0-1 1 ¢ | f

&.C.

3
g’_

]___‘

110864-00 | 7

L.E.D. HOLDER

[

1211813-00

SIODE

1301425-00 |5

DE ,L.E.D.

|DI-DS

(FOR EXAMPLE,
CHARACTOR
LAXX-PK)
OPTION SET

5011726

RESISTOR 300 /4W 5%

A T

DIMS APE REF ONLY

FIRST USED ON OPTION MODEL

LAZD

QTY

REF. DESIGNATION

ETCH BOARD REV.

|C |

N8% %,

~ S

14
7 ANDABOVE
ARE USUALLYAREPINSTATED
GND AND 5VEXCEPTIONS
RESPECTIVELY
I PIN LOCATIONS

$ [RE

[

:: “ E

N
=

DESCRIPTION

PARTS LIST

[

' . J»“;’

PART NO.

Iii i

ENG.

= .

77/5'[75 TITLE

Ll e

[

dlijgli[t|all

DATE

Y . |Tixas
Reh

51181813

e R

ILEOM

FRONT PANEL

CONTROL, ASSY REV.

NUMBER
C]
5411727-0-1
D 'C Q [T
SAE 1 /]Tor1 Tos.,
DEC NO. CHARTEIA NO. SHEET
EIA NO. CONVERSION
DEC NoO.SEMICONDUCTOR
[ [ [ [ [
C-AD-7011525-0-0 SIZE cooe[

A-46

PIVENT CORPORATION

SOLDERING SHALL NOT EXCEED 285°C

o
o
2
ASSY /DRILLING HOLE LAYOUT |D-AH-5911049-0-5,

REF

rRI,R2

B-WH-5911095-0-¢| 3

POTENTIOMETER /10K

13091S0-12 | 5

CIRCUIT

BOARD

DA 501053909 4

¢y

5/ 190G

/) STOR
PHOTO TR ZNS

2./;'/N/5H£D HOL%SfifVF%/ZBAfi)gI;/TING Q/ AND Q2

MODULE ECO HISTORY
ETCHED

FOR A PERIOD OF /5 SECONDS.
HALL BE .07

1
BJa) 2 |
| [5T-0-68011¢5
X-Y COORDINATE HOLE LOCATIO K-CO-54//04)€41 /

REF

). HEAT APPLIED TO Q) AND Q2 DURING

coPvRignT O 1974 DIs) AL

REF

NOTES.

o sae o tome bt
o venefo i Tanutechur

wrllDn PErTRNeIen

Sreerg nd oaccovoms rerer s e $r00
Toe
mdmwwm“‘m":“:::

)

IN.,.

A RIAND R2 MUST BE ORIENTED AS SHOWN,

W/ TH NOTCH TOWARARD CENTER OF BORRD

|
NOTE 3

}

750

REF

NOTES 1§2

TRIM TO .03 MAX

—

]
O

.920 REF-

1:Q

B
?
e D

= PT COLL

+5V m—

POT

10K

=
<

P T COLL2
———————————

]

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‘

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‘

PARTS LIST

ETCH BOARD Rev

KN b

| |

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EQUIPMENT

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PART NO

DESCRIPTION

REF DESIGNATION

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EIA NO.

DEC NO.

EA N0 |0

SEMICONDUCTOR CONVERSION CHART
3

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STE|CODE

NUMBER

pDlcsl 5411049-0-1

sT T 1T 1T 1 1 [
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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

dlilgliltlall

EK-LA36-IP-004

| LLUSTRATED

LA36

PARTS

DECwriter Il

BREAKDOWN
HOW TO USE THE IPB
GENERAL

ECO Cut-In — The notation at the top of this column indicates the

This IPB is compiled following the organization and nomenclature

ECO level of the system (option), at which the IPB was initially

of the engineering drawing structure.

prepared. Subsequent ECO level designations, that modify existing

MAJOR ASSEMBLY LOCATOR

column next to the part that is added or modified. A bracket ([)

parts or add new parts to the device, are inserted in the ECO Cut-In

The Major Assembly Locator (first illustration) is an index that
provides a description and a figure reference for all illustrations used

preceding the item description is used to indicate the parts affected

by ECO’s.

in this manual.

Vendor Code/Part No. — Indicates vendor parts that are not stocked

INDENTED PARTS LIST

This manual identifies each assembly being broken down (figure
reference

callout),

and

all

parts

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

DEC.

Refer to the

Field Service Spares Catalog (vendor part

number to DEC part number) for the vendor code cross-reference.
Used On Code — l_etters 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. For 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.

identification, provides a means for the user to identify the next

SYMBOL USAGE

higher assembly item and make alternate selections for parts when

Hardware Designators — Alpha designators for screws (S), washers

the

required

replacement

part

assembly

not

immediately

available.

(W), nuts (N), and retaining rings (R) are inserted after the item
number callouts on the illustration when stacked item numbers are

used.

COLUMN CALLOUT DESCRIPTION
Figure & Item — Indicates the figure number and item number of

Attaching

each part.

that is used as attaching hardware. Attaching hardware is denoted as

Hardware — The @ symbol is inserted before any part

those parts that are not an integral part of the referenced assembly.

Description
—
Lists the
name of
the part
and pertinent
specitications (when required). Asterisks preceding the description

(NFR) Not Field Repairable — The (NFR) symbol is inserted after

denote the subordination of the part to the next higher assembly.

any assembly that is not to be field dismantled.

DEC Part No. — Lists the DEC part ordering number. A blank in

Other Symbols

this column indicates

accessories, etc., will be explained and appear as part of the item

a DEC part number was not assigned at the

— Any other symbols that are required for kits,

description.

time of publication.

REVISION HISTORY
PRINTING

ECO

3rd Printing | LA36
g

70-096994

4th Printing | LA36

70-09694

LEVEL

DATE

00001-00184

PAGES AFFECTED

2-18-76 | This 3rd Printing EK-LA36-IP-003

00000—00000

00001-00251 |

00000-00000

SUPERSEDES 2nd Printing EK-LA36-1P-002

9-23-76

This 4th Printing EK-LA36-1P-004

SUPERSEDES 3rd Printing EK-LA36-1P-003

DEC is not responsible for errors which may appear in the technical
description (including illustrations and photographs) of the products

DEC reserves the right, without

covered by this manual.

modifications in
manual

and

notice, to make substitutions and

the specifications of products documented in this

further

reserves

the

right

products from the market without notice.

withdraw

any of these

None

the

granting of any

descriptions

contained

this

manual

imply

the

license whatsoever to make, use or sell equipment

constructed in accordance therewith.
Printed in

U.S A,

D.C. MOTOR and ENCODER ASSEMBLY

Fig. 9
PRINTER MECHANISM ASSEMBLY

Fig. 3
RIBBON CHASSIS ASSEMBLY
Fig. 4

RIBBON DRIVE ASSEMBLY

Fig. 5

IDLER GEAR ASSEMBLY
Fig. 7
KEYBOARD BEZEL ASSEMBLY
Figs. 12, 12A

CARRIAGE ASSEMBLY
Fig. 6

KEYBOARD BEZEL ASSEMBLY (W/Cursor Control)

Figs. 13, 13A

wmumu"im

;mmnuumu

lLsum‘m.

‘Q

[]

gty

oe——

R St-

TRANSFORMER ASSEMBLY
Figs. 8, 8A

CABLE and HARNESS ASSEMBLY
Figs. 10,11, 11A, 14

LA36 DECwriter ASSEMBLY
Figs. 1, 1A

CABINET ASSEMBLY (W/Power Supply)
Fig.2,2A

LA36-01

Major Assembly Locator, LA36 DECwrit

er |/

172

IPB-LA36

dlilgli |t}

PARTS LIST

11S

12W
25W

LA36-02

Figure 1.

LA36 DECwriter Assembly

IPB-LA36

FIG

ITEM

DEC

NO.
1—

DESCRIPTION

ECO

CUT-IN
LA36

USED ON

PART NO.

00001

CODE

VENDOR
CODE]

REF

FIG

PART NO. | NO.

MODEL LA36 DECwriter ||

Code A used on LA36-CA

LA36-CA

00165

(20 mA Current Loop, Numeric Pad, 115V)
Code B used on LA36-CB
(deleted)

(deleted)

LA36-CB

00165

(20 mA Current Loop, Numeric Pad, 230V)
Code C used on LA36-CC
(deleted)

LA36-CC

00165

LA36-CD

00165

(deleted)

LA36-DA

00165

(deleted)

LA36-DB

00165

(deleted)

LA36-DC

00165

LA36-DD

00165

(20 mA Current Loop, Numeric Pad, 115V,
PDP-10)

Code D used on LA36-CD

(deleted)

(20 mA Current Loop, Numeric Pad, 230V,
PDP-10)

Code E used on LA36-DA
(20 mA Current Loop, 115V)

Code F used on LA36-DB
(20 mA Current Loop, 230V)

Code G used on LA36-DC

(20 mA Current Loop, 115V, PDP-10)

Code H used on LA36-DD

(deleted)

(20 mA Current Loop, 230V, PDP-10)
1

*CABINET ASSEMBLY W/POWER SUPPLY
(115Vv)

*CABINET ASSEMBLY W/POWER SUPPLY

(230V)

70-09648-01

(deleted)

[guide, Paper (deleted)
uide, Paper

(added)

ACEG

BDFH

00138

70-09648-02

74-11430-00
74-12158-00

*Screw, Phl Pan Hd No. 8-32 x .38

90-06037-01

*Washer, Flat No. 8

90-06660-00

*Washer, Lock Split No. 8

90-06690-00

*PRINTER MECHANISM ASSEMBLY

70-09696-00

*Screw, Phl Pan Hd No. 10-32 x .94

90-08955-01

00138
00052

*Washer, Lock Split No. 10

90-07906-00

*Nut, Well No. 10-32

90-08896-00

*PRINT HEAD ASSEMBLY (NFR)

70-09883-00

*Screw, Phi Pan Hd No. 6-32 x .56

90-07793-01

*Washer, Lock Int Tooth No. 6

90-06633-00

*Clamp, Cable

12-02704-00

*Tape, Double Coated, .50 Wide

90-07834-00

*Screw, Phl Pan Hd No. 4-40 x .38

90-06011-01

*Washer, Flat No. 4

90-06658-00

*Nut, Kep No. 4-40

90-06557-00

*KEYBOARD BEZEL ASSEMBLY

70-09750-01

EFGH

*KEYBOARD BEZEL ASSEMBLY

70-09750-02

ABCD

A—H

(With Numeric Pad)

*CABLE ASSEMBLY (LA36 Keyboard)

70-10000-00

*Jumper (LA36 Keyboard, Not Shown)

70-10001-04

*Cable Tie

90-07031-00

*Screw, Phl Pan Hd No. 6-32 x .38

90-06022-01

*Washer, Lock Ext Tooth No. 6

90-07649-00

*Washer, Lock Split No. 6

90-07801-00

*Washer, Flat No. 6

90-06653-00

IPB-LA36

FIG

ECO

CUT-IN

ITEM

DEC

NO.

DESCRIPTION

LA36

PART NO. | 00001

VENDOR
USED ON

CODE

REF
FIG

CODE|

PART NO. | NO.

1—

*CABLE ASSEMBLY (BCOS5SF Interface)

BCObGF-15

*Ribbon Spool (w/Ribbon)

36-10558-00

ABEF

*Ribbon Spool (Empty)

36-10966-00

29
30

*Clamp, Cable
(deleted)
*Screw, Phl Pan Hd No. 10-32 x .38 (deleted)

*Washer, Flat No. 10

(deleted)

90-07089-00
90-06071-01

00052
00052

*Nut, Kep No. 10-32

(deleted)

90-06565-00

00052

*Connector, P2, Pin Housing, Mate-N-Lok

*Housing

*Screw, Phl Pan Hd No. 6-18 x .50 (Self Tapping) | 90-09630-01

*Cover

74-11122-00

*Clip, Cover

74-11818-00

*Screw, Phl Pan Hd No. 6-18 x .38 (Self Tapping) | 90-09622-01

39
40
41

*Nameplate (LA36)
*Washer, Buna
* Jumper

| 90-06664-00 | 00052
12-09340-01

(Plugs into PB-J5)

74-11116-00

(added)
(added)

36-11826-00
90-09684-00
70-10001-07

00053
00052

Accessories/Options
tPaper (Package of 100 sheets)

74-12103-00

tBasket, Paper

74-12016-00

tTable Top

34-11736-00

tBracket, Table Support

74-11972-00

tTable Assembly

70-09897-00

tWheel Assembly

70-09751-00

tWheel, Caster

74-11826-00

tBracket, Wheel

74-11824-00

5/6

IPB-LA36

dlilgliltla

)

PARTS LIST

LA36-02A

Figure 1A. LA36 DECwrite

r Assembly

IPB-LA36

FIG

ECO

ITEM

DEC

NO.

1A—

DESCRIPTION

CUT-IN
LA36

USED ON

PART NO. | 00165

CODE

VENDOR
CODE|

REF
FIG

PART NO. | NO.

MODEL LA36 DECwriter ||

Code J — Used on Model LA36-CE

LA36-CE

LA36-CF

LA36-CH

LA36-CJ

LA36-DE

LA36-DF

LA36-DH

LA36-DJ

(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 Q — 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)

LA36-AE

00247

(60 Hz, 90-132V, BELL CANADA)
1

*CABINET ASSEMBLY W/POWER SUPPLY

70-09648-01

J,N

70-09648-02

M, R

*CABINET ASSEMBLY W/POWER SUPPLY

70-09648-03

L, Q

(115V, 50H2)
*CABINET ASSEMBLY W/POWER SUPPLY

70-09648-04

K, P

(230V, 60 Hz)
*CABINET ASSEMBLY W/POWER SUPPLY

70-09648-05

00247

J-R
S

3
3

NPQR
S
JKLM

12A
12A
13A

(115V, 60 Hz)

*CABINET ASSEMBLY W/POWER SUPPLY
(230 V, 50 Hz)

(115V, 60 Hz) (added)
2

*Guide, Paper

74-12158-00

*Screw, Phl Pan Hd No. 8-32 x .38

90-06037-01

*Washer, Flat No. 8

90-06660-00

*Washer, Split Lock No. 8

90-06690-00

*PRINTER MECHANISM ASSEMBLY
*PRINTER MECHANISM ASSEMBLY (added)

70-09696-00
70-09696-01

*Screw, Phl Pan Hd No. 10-32 x .94

90-08955-01

*Washer, Split Lock No. 10

90-07906-00

9
10

*Nut, Wall No. 10-32
*PRINT HEAD ASSEMBLY (NFR)

90-08896-00
70-09883-00

*Screw, Phl Pan Hd No. 6-32 x .56

90-07793-01

*Washer, Internal Tooth Lock No. 6

90-06633-00

*Clamp, Cable

12-02704-00

*Tape, Double Coated .50 wide

90-07834-00

*Screw, Phl Pan Hd No. 4-40 x .38

90-06011-01

*Washer, Flat No. 4

90-06658-00

*Nut, Kep No. 4-40

90-06557-00

*KEYBOARD BEZEL ASSEMBLY
*KEYBOARD BEZEL ASSEMBLY (added)
*KEYBOARD BEZEL ASSEMBLY W/CURSOR

70-09750-01
70-09750-03
70-09750-02

00247

CONTROL

*KEYBOARD CABLE ASSEMBLY

70-11519-00 | See Note 1

*Jumper (deleted)

70-10001-11

11A

00241

IPB-LA36

FIG

ECO

CUT-IN

ITEM

DEC

NO.

DESCRIPTION

LA36

VENDOR
USED ON

PART NO. | 00165

*Cable Tie

90-07031-00

*Connector, (P2) Pin Housing 8 Pin Mate-N-Lok

12-09340-01

CODE

|REF
FIG

CODE]

PART NO. | NO.

(Not shown)
23

*Cable Tie Mount (Not shown)

90-07867-00

*Housing

74-11116-00

*Housing (added)

74-11116-01

*Screw, Phl Pan Hd No. 6-18 x .50 Self Tapping

90-09630-01

*Cover

74-11122-00

*Cover (added)

74-11122-01

*Clip, Cover

74-11818-00

J-R

00247

J-R

00247

*Screw, Phl Pan Hd No. 6-18 x .38 Self Tapping

90-09622-01

*Washer, Flat No. 6

90-06653-00

*Nameplate, LA36

36-11826-00

*Nameplate, LAS36 (added)

36-13249-00

00247

*Washer, Buna (deleted)

90-09684-00

00172

*Jumper

70-10001-07

*Jumper

70-10001-06

*Decal, CAUTION/WARNING (deleted)

36-12483-00

J-R

*Decal, LA36 (added)

74-15561-00

*Spacer, Bezel

74-13675-00

00204

*Tubing, Heat Shrinkable

91-07253-09

*Tie Wrap, Screw Down

90-07033-00

*Clip, Harness

90-08340-00

*Fuse Holder (deleted)

12-11638-00

*Washer, Ext. Tooth Lock No. 8

90-08072-00

*Nut, Kep No. 8-32

90-06563-00

*Decal, Ground Symbol

36-12680-00

*Cable, Paper Out (deleted)

70-11657-00 | See Note 2]

J-M

*Jumper, Paper Out (added)
*Tab, Adapter (added)

70-10001-14
90-09797-00

J-M
J-M

00241

00219
00219

*Switch, Rework

74-12424-00 | See Note 2

J-M

*Screw, Ph Pan Hd No. 4-40 x 9/16

90-08033-01 | See Note 2

J-M

*Nut, Kep No. 4-40

90-06557-00 | See Note 2

J-M

*Jumper (added)

70-10001-13

00219

J, K

*Print Window (added)

12-12009-00

00206

J-M, Q-S

*Mount, Cable Tie, Adhesive Backed (added)

90-08264-00

00179

*Cable Tie (added)

90-07880-00

00179

ACCESSORIES

tPaper, Package of 100 Sheets

74-12103-00

tRibbon Spool, W/Ribbon

36-10966-00

tRibbon Spool, Empty

36-10558-00

LABELS/DECALS (Not Shown)
tSerial No. Tag (added)

36-13210-00

00241

tCSA Decal (added)

36-13211-00

00241

tLabel, LA36

36-12391-00

tLabel, Adhesive Back (RF1 Supression) (added)

36-13088-00

Note 1:

00248

M, R

This Assembly no longer installed at this

level. (Per ECO LA36-00205). See Figure
12 A.

Note 2:

Items 43, 45, 46, 47 formally installed

under Cabinet Assembly Figure 2. (Per ECO

LA36-00190)

9/10

IPB-LA36

23115V — 2 AMP

dlijgliltla

23-230V — 2 AMP

)

PARTS LIST

23115V — 2 AMP TM|
24-230V — 1 AMP

LA36-03

Figure 2. Cabinet Assembly (w/Power Supply)

IPB-LA36

FIG

ECO

ITEM
NO.

2—

DESCRIPTION

DEC

LA36

USED ON

PART NO.

00001

CODE

ACEG

CABINET ASSEMBLY W/POWER SUPPLY (230V) | 70-09648-02

BDFH

*Frame Assembly

70-09649-00

*Foot, Leveling (deleted)

90-07601-00

*Foot, Leveling (added)

90-09685-00

*Closure, Tubing (deleted)

12-11067-00

*Closure, Tubing (added)

12-11067-02

*Bumper, Rubber

90-09567-00

*Fan, 115V (115 CFM) Rotron or IMC

12-09403-01

PART NO. | NO.

CABINET ASSEMBLY W/POWER SUPPLY (115V) | 70-09648-01

2
3

FIG
CODE]

*Fan 115V (100 CFM) Torin (added)

12-11993-00

*Screw, Phl Pan Hd No. 8-32 x 1.75

90-06046-01

(For Rotron or IMC Fan)
*Screw Phl Pan Hd No. 8-32 x .25 (added)

90-06035-01

00059

00055

(For Torin Fan)
7

*Washer, Lock Split No. 8 (For all fans)

90-06690-00

*Washer, Flat No. 8 (For all fans)

90-06660-00

*POWER CORD ASSEMBLY (115V)

70-09673-00

ACEG

*POWER CORD ASSEMBLY (230V)

70-09673-01

BDFH

*Plate, Cover

74-11607-00

*Strain Relief

90-08509-00

*Strain Relief

90-09572-00

*Screw, Phl Pan Hd No. 8-32 x .38

90-06037-01

*Washer, Lock Split No. 8

90-06690-00

*Washer, Filat No. 8

90-06660-00

*Capacitor (C1) 33,000 MFD

10-11545-00

*Capacitor (C2) 18,000 MFD

10-11643-00

*Capacitor (C3,C4) 14,000 MFD

10-10187-00

*Tie Wrap

90-09350-00

*HARNESS ASSEMBLY, Capacitor

70-09895-00

*Bracket, Fuse Mounting (deleted)

74-11925-00

*Holder, Fuse

12-11638-00

*Fuse, Slo-Blo 2 amp

90-07216-00

*Fuse, Slo-Blo 1 amp

90-07212-00

*Capacitor (C5) .1 MFD 1000V (deleted)

10-00034-00

00052

*Screw, Phl Pan Hd No. 6-32 x .38 (deleted)

90-06022-01

00052

*Nut, Kep No. 6-32 (deleted)

90-06560-00

00052

*Jumper

70-10001-01

*Jumper

70-10001-02

*Jumper

| *TRANSFORMER ASSEMBLY

10
00052
ABCDEFGH
BDFH

70-10001-03

70-09779-00

*POWER BOARD ASSEMBLY (LA36)

54-10805-00

*LOGIC BOARD ASSEMBLY

M7722

*Door, Cabinet

74-11120-00

*Bushing, Snap-in Nylon

90-09561-00

*Bushing, Nylon

90-09565-01

*Screw, Hex Cap Hd No. 3/8-16 x 1.0

90-08922-09

*Catch, Door Strike

90-09571-00

*Catch, Door Latch

90-09571-01

*Jumper (115V)

70-09905-01

*Jumper (230V)

70-09905-02

*Strap, Ground (added)

90-06990-00

00021

*Nut, Kep. No. 8-32 (added)

90-06563-00

00021

*Decal, Fuse (added)

74-13384-00

00052

*Filter, EMI (added)

12-12003-00

00052

*Jumper (added)

70-10001-04

00052

47
48

*Cover, EMI Filter (added)
*Washer, Lock Ext Tooth No. 8 (added)

74-13286-00
90-08072-00

00052
00052

*Grommet, Rubber (added)

90-07013-00

00052

IPB-LA36

ACEG
BDFH

dlilglitla

)

PARTS LIST

LA36-03A

Figure 2A

Cabinet Assembly W/Power Supply

IPB-LA36

FIG

ECO
CUT-IN

&
ITEM

LA36

USED ON

DESCRIPTION

PART NO.

00118

CODE

CABINET ASSEMBLY W/POWER SUPPLY 115V

70-09648-01

NO.

2A—

VENDOR

DEC

REF
FIG

CODE}]

PART NO. | NO.

ACEG

BDFH

(deleted)
CABINET ASSEMBLY W/POWER SUPPLY 115V

70-09648-01

00138

60Hz (added)

CABINET ASSEMBLY W/POWER SUPPLY 230V

70-09648-02

(deleted)
CABINET ASSEMBLY W/POWER SUPPLY 230V

70-09648-02

00138

70-09648-03

00138

70-09648-04

00138

70-09648-05

00247

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)
1

*Frame Assembly

70-09649-00

*Foot, Leveling (deleted)

70-07601-00

FCIosure, Tubing (deleted)

*Foot, Leveling (added)

90-09685-00

00059

12-11067-00

*Closure, Tubing (added)

12-11067-02

00059

;Bumper, Rubber (deleted)

90-09567-00

00118

*Fan, 115V (115 CFM) Rotron or IMC (deleted)

12-09403-01

*Fan, 115V (100 CFM) Torin (deleted)

12-11993-00

*Fan,

12-12581-02

00142

90-06046-01

00142

00164

115V (35 CFM) (added)

*Screw, Phl Pan Hd No. 8-32 x 1.75 (For Rotron)

(deleted)

*Screw, Phl Pan Hd No. 8-32 x .38 (added)

90-06037-01

*Washer, Split Lock No. 8

90-06690-00

*Washer, Flat No. 8

90-06660-00

*POWER CORD ASSEMBLY (115V) (deleted)

70-09673-00

*POWER CORD ASSEMBLY (120V) (added)

70-09673-00

*POWER CORD ASSEMBLY (230V) (deleted)

70-09673-01

h’POWER CORD ASSEMBLY (230V) (added)

70-11045-00

*Plate, Cover

74-11607-00

*Strain Relief (deleted)

90-08509-00

*Strain Relief (added)

90-09678-00

*Strain Relief

90-09572-00

ACEG
00138

JNLQS

00138

MRKP

BDFH

00164

*Capacitor, 33,000 MFD

10-11545-00

Capacitor, 18,000 MFD (deleted)

10-11643-00

Capacitor, 37,000 MFD (added)

10-10426-00

*Capacitor, 14,000 MFD

10-10187-00

*Cover, Capacitor (added)

74-15114-00

00164

*Spacer, Aluminum No. 10-32 x 3/8 x 3.00

90-06881-00

00164

00138

(added)
18

*Screw, Phl Pan Hd No. 10-32 x .50 (added)

90-06073-00

00164

*Washer, Split Lock No. 10 (added)

90-07906-00

00164

*Washer, Flat No. 10 (added)

90-06664-00

00164

| *Tie Wrap

90-09350-00

*HARNESS ASSEMBLY (Capacitor)

70-09895-00

*Bracket, Fuse Mounting (deleted)

74-11925-00

*Fuse Holder

12-11638-00

*Fuse, Slo-Blo 2 amp

90-07216-00

EFuse, Slo-Blo 1 amp (deleted)

*Decal, Fuse, LA36

74-13384-00

Fuse, Slo-Blo, 1.5 amp (added)

90-07212-00

90-09740-00

00052

00138

*Fuse, Slo-Blo 3 amp

90-07218-00

*Capacitor, .1 MFD, 1000V (deleted) .

10-00034-00

00052

*Screw, Phl Pan Hd No. 6-32 x .38 (deleted)

90-06022-01

00052

*Nut, Kep No. 6-32 (deleted)

90-06560-00

00052

IPB-LA36

MRKP
JNLQS

FIG

ECO

CUT-IN

ITEM

DEC

NO.

DESCRIPTION

LA36

PART NO. | 00118

[‘Jumper, (deleted)

70-10001-04

*Jumper, (added)
*Jumper, (deleted)

70-10001-08
70-10001-02

00139
00139

*Jumper, (added)

70-10001-12

00177

*Jumper, (added)

70-10001-11

00161

*Filter, EMI (added)

12-12003-00

00052

*Filter, EMI (deleted)

12-12003-00

*Filter, EMI (added)

12-12877-00

00218

*Cover, EMI Filter (added)
*Grommet, Rubber (added)
*Washer, External Tooth No. 8 (added)

74-13286-00
90-07013-00
90-08072-00

00052
00052
00052

*Nut, Hex No. 8-32 (added)

90-06561-00

00163

|[*Spacer, No. 8 x .75 (added)

90-07868-00 | 00163

*Spacer, No. 8 x .75 (deleted)

90-07868-00

37
38
39

|*Spacer, No. 8 x 1.00 (added)

VENDOR
USED ON

CODE

REF
|

|CODE|

FIG

PART NO. | NO.

90-09285-00 | 00225

*Washer, Internal Tooth (added)

90-08292-00

00156

*Grommet (added)

90-09718-02

00156

*Grommet (added)

90-09718-03

00156

*TRANSFORMER ASSEMBLY (deleted)

70-09779-00

*TRANSFORMER ASSEMBLY 60 Hz (added)
*TRANSFORMER ASSEMBLY 50 Hz (added)

70-09779-01
70-09779-02

*Power Board Assembly

54-10805-00

*Logic Board Assembly (deleted)

M7722

*Logic Board Assembly (deleted)

M7723

*Logic Board Assembly (added)

M7728

00135

J-R

*Logic Board Assembly (added)

M7728-YA

00247

*Jumper,

110V

70-09905-01

*Jumper, 220V

70-09905-02

*Clip, Harness (added)

90-08340-00

00162

*Grommet (added)

90-07018-00

00162

*Ground Strap (added)

90-06990-00

00162

63
54

*Nut, Kep No. 8-32 (added)
*Tubing, Heat Shrinkable (added)

90-06563-00
91-07253-09

00162
00161

A-H

00138
00138

8A
8A

00103

JNLQS
MRKP

*Cable, Paper Out

70-11657-00

See Note

*Switch, Rework

74-12424-00

See Note

*Paper Guide

74-12158-00

See Note

*Screw, Phl Pan Hd No. 4-40 x 9/16

90-08033-01

See Note

*Nut, Kep No. 4-40

90-06557-00

See Note

*Foam, Protective

74-14144-00

*Door, Cabinet

74-11120-00

*Bushing, Snap in Nylon (deleted)

90-09561-00

00164

*Bushing, Nylon (deleted)

90-09565-00

00164

*Screw, Hex Hd Cap No. 3/8-16 x 1.0 (deleted)

90-08922-09

00164

*Pivot, Door (added)

74-15068-00

00164

*E-Ring, External (added)

90-09773-00

00164

*Screw, Special (added)

74-15067-00

00164

*E-Ring, External (added)

90-09772-00

00164

*Catch, Door Strike

90-09571-00

*Catch, Door Latch

90-09571-01

*Decal, Ground (added)

36-12680-00

00162

*Fuse Holder (added)

12-12893-00

00177

JNKPS
MRLQ

IPB-LA36

FIG

ECO

CUT-IN

ITEM

NO.

DESCRIPTION

LA36

USED ON

PART NO.

00118

CODE

*Spacer, Fuse Holder (added)

74-15374-00

00177

*Clip Enclosure (added)

74-17011-00

00244

*Cover, Transformer Opening (added) -

74-17012-00

00244

*Washer, Flat (added)

90-07983-00 |

00244

tLabel, Fuse Rating (Not Shown)

74-12548-00

Note:

Items 55, 56, 57, 58, 59 no longer installed

at this Assembly Level. (See Figure 1A. Per

ECO LA36-00190.)

IPB-LA36

VENDOR

DEC

REF
FIG

CODE]

PART NO. | NO.

ilRTSltLIalSTl
PA

LA36-07A

mbly (Sheet 1 of 2)

anism Asse
Figure 3 Printer Mech

lPB-LA36
17

PARTS LIST

LA36-078B

Figure 3

IPB-LA36

Printer Mechanism Assembly (Sheet 2 of 2)

FIG

ECO

ITEM

DEC

NO.

DESCRIPTION

USED ON

CODE

PRINTER MECHANISM ASSEMBLY

70-09696-00

A—R

*Plate, Side (LH)

74-11028-01

*Plate, Side (RH)

74-11028-02

*Shaft, Tractor Drive

74-11075-00

*Shaft, Tractor Support

74-11076-00

3—

PRINTER MECHANISM ASSEMBLY (added)

[*TRACTOR ASSEMBLY (RH) (deleted)

70-09696-01

00247

00173

r_**Shaft, Screw (deleted)

74-11908-00

00173

**Retaining Ring (added)

90-09582-00

00039

*Screw, Tractor Lock (added)

[ *TRACTOR ASSEMBLY (LH) (deleted)
|
*TRACTOR ASSEMBLY (LH) w/Lock (added)

00173

90-06664-00

00028

*Bushing, Tractor Shaft Retaining

74-11425-00

*Retaining Ring

90-09579-00

*Retaining Ring Push-on

90-09257-00

*Retaining Ring (deleted)

90-07975-00 |

*Retaining Ring Prong Lock

90-09581-00

*Collar, Side Plate

74-11098-03

*Hub, Clutch

74-11441-00

*Gear, Drive Clutch

74-11440-00

*Washer, Clutch

74-11443-00

*Knob, Line Feed

74-11437-00

*Spring, Compression

90-09592-00

*Retaining Ring

90-09580-02

* Adapter, Line Feed

__*Retaining Ring (added)

|_*Spring, Compression (deleted)

74-12535-00
90-09644-00 |

00028

12-12353-00 |

00154

12-12353-00

00173

90-07858-00

00154

|__*Washer, .697 OD x .375 ID x .062 (deleted)

90-07858-00

00173

|__*Screw, Phl Pan Hd No. 6-32 x .38 (added)

90-09591-01
90-06022-00

*Washer, Flat No. 6

90-06653-01
90-06633-00

*Washer, Int Tooth Lock No. 6

*Shaft, Carriage

74-11033-00

*CARRIAGE ASSEMBLY

70-09692-00

*Bushing, Plain

74-11108-00

00028

*Washer, .697 OD x .375 ID x .062 (added)
*Screw, Nylock 6-32 x.50 (deleted)

1. 1A

74-14433-00

| 12-11662-04

PART NO. | NO.

70-09693-04

*Washer, Flat No. 10 (deleted)

*Spring, Compression (added)

|CODE|

90-09582-00 | 00173

FIG

70-09693-03

_*TRACTOR ASSEMBLY (RH) w/Lock (added) | 12-11662-05

|__**Retaining Ring (deleted)

LA36

PART NO. | 00001

*PRINT BAR ASSEMBLY (deleted)

70-10683-00

*Print Bar (added)

74-11072-00

*Pivot, Lower

74-11439-00

*Ratchet, Pivot

74-11103-00

*Screw, Phl Pan Hd No. 8-32 x .38

90-06037-01

*Washer, Split Lock No. 8

90-06690-00

*Washer, Flat No. 8

90-06660-00

*RIBBON CHASSIS ASSEMBLY

70-09689-00

*Retaining Ring

90-09580-00

*Frame, Ribbon Idler w/Bushing

74-11576-00

*Retaining Ring

90-09273-00

*Washer, Flat No. 10

90-06664-00

*Washer, Split Lock No. 10

90-07906-00

00028

00188

IPB-LA36

FIG

ECO

CUT-IN

ITEM

NO.

DESCRIPTION

VENDOR

DEC

USED ON

PART NO.

CODE

REF
FIG

CODE|]

PART NO. | NO.

3—

*Screw, Socket Hd Cap No. 10-32 x .50

90-06346-08

*Spring, Compression

90-09673-00

*Nut, Lock No. 8-32

90-09061-00

*Screw, Socket Hd Cap No. 8-32 x 1.00

90-07988-08

*Spring (added)

74-13699-00

00082

*Wick (added)

74-13698-00

00082

*Reservoir, Oil (added)

74-13672-00

00082

*DC MOTOR and ENCODER ASSEMBLY

70-09691-00

EBelt, Timing (deleted)

12-11583-00

*Belt, Timing (added)

12-11583-01

*Retainer, Bumper Spring

74-11412-00

*Spring, Carriage Bumper

74-11816-00

*Screw, Phl Pan Hd No. 10-32 x 2.00

90-06081-01

*IDLER GEAR ASSEMBLY

70-09694-00

*Shaft, Idler

74-11575-00

*Standoff, Hex .620

90-09583-00

*Washer, Flat No. 8 x .062

90-06662-00

*Stepping Motor, 16 V DC

12-11563-00

*Nut, Kep No. 8-32

90-06563-00

*Screw, Hex Hd Machine No. 1/4-20 x .62

90-06242-09

*Washer, Split Lock No. 1/4

90-07797-00

*Washer, Flat No. 1/4

90-06676-00

*RIBBON DRIVE ASSEMBLY

70-09690-00

*Spring, Compression

90-09578-00

00155

00226

*Ground Strap

70-10001-05

*Decal, Ground Symbol (added)

36-12680-00 | 00166

*Nut, Kep No. 6-32

90-06560-00

*Speaker, 2-1/2 in. Perm Magnet

12-10299-00

72
73
74

*Screw, Ph! Truss Hd No. 10-32 x .50 (added)
*Washer, External Lock No. 10 (added)
*Nut, Hex No. 10 (added)

90-06073-03
90-07651-00
90-06564-00

00189
00189
00189

*Bracket, Cover Interlock (added)

74-15802-00

00220

*Switch, Interlock (added)

12-12255-01

00220

77
78
79

*ROTARY SWITCH ASSEMBLY (added)
**Rotary Switch (added)
**Terminal, Quick Disconnect (added)

70-12781-00
00251
12-13187-00 | 00251
90-07655-01 | 00251

S
S
S

*Decal, Parity (added)

74-16535-00 | 00251
12-10114-00 |

00251

90-07081-00 |
90-06024-00 |

00251
00251

S
S

81
82
83

IPB-LA36

*Knob, Black (added)
*Clamp, Cable 1/4 (added)
*Screw, Phl Pan Hd No. 6-32 x .50 (added)

flfl@flflfifl>
PARTS LIST

LA36-09A

Figure 4. Ribbon Chassis Assembly

IPB-LA36

FIG

ECO

CUT-IN

ITEM

70-09689|

USED ON

DESCRIPTION

PART NO.

00001

CODE

RIBBON CHASSIS ASSEMBLY

70-09689-01

NO.
4—

LA36
00213

*Chassis, Ribbon w/Inserts

70-09680-00

*Base Assembly, Ratchet

70-09697-00

*Spring, Upper Pawl

74-11105-00

*Spring, Main Pawl

74-11090-00

*Pivot, Ratchet

74-11103-00

*Washer, Ratchet

74-11061-00

*Screw, Phl Pan Hd No. 8-32 x .31

90-06036-01

*Washer, Lock Int Tooth No. 8 (deleted)

90-06634-00

LA36
00113

*Washer, Split Lock No. 8

90-06690-00

*Washer, Flat No. 8

90-06662-00

*Guide, Shoe

74-11419-00

*Screw, Phl Pan Hd No. 8-32 x .38, Self Tapping | 90-09586-01

*Collar, Side Plate

74-11098-02

*Disk, Friction

74-11405-00

LA36
00083

*Wheel, Ratchet

__*_Driver, Spool

*Spring, Compression (deleted)

74-11432-00

74-11048-00

90-09584-00

LA36
00116

*Spring, Compression (added)

12-12353-00

*Washer, Brake (deleted)

74-11106-00

LA36
00079

*Retaining Ring (deleted)

90-09580-00

LA36
00079

*Interposer, L.H.

74-11058-01

*Interposer, R.H.

74-11058-02

*Spring, Interposer

[*Washer, Flat No. 6 (deleted)

74-11087-00

90-06707-00 |

LA36
00113

*Washer, Flat No. 6 (added)

90-06634-00

*Washer, Flat No. 6 (deleted)

90-06634-00

LA36

90-06707-00 |

00186

|
*Washer, Flat No. 6 (added)
23

*Sensor, Reverse

74-11060-00

*'U’ Clip (added)

90-09748-00

LA36
00143

*Cap, Standoff Spool

74-12976-00

*Screw, Phl Pan Hd No. 8-32 x 2.75 (added)

90-06050-01

LA36
00083

*Washer, .687 x .375 (added)

90-07858-00

LA36
00083

*Washer, .625 x .200 (added)

90-06668-00

LA36
00083

*Nut, Elastic Stop No. 8-32 (added)

90-09061-00

LA36
00083

IPB-LA36

VENDOR

DEC

REF
FIG

CODE|

PART NO. | NO.
3

FIG

ECO
CUT-IN

ITEM

DEC

- NO.
5—

DESCRIPTION

LA36

PART NO. | 00001

RIBBON DRIVE ASSEMBLY

70-09690-00

*Bracket, Ribbon Drive

74-11113-00

*Bearing, Self Aligning

12-11649-00

*Shaft, Ribbon Idler

74-11068-00

*Ribbon Eccentric, w/Clutch

74-11578-00

74-11084-00

*Rod, End

*Bearing

12-11650-00

*Screw, Soc Hd Cap No. 4-40 x .12

90-09651-08

*Screw, Phl Pan Hd No. 8-32 x .31

90-06036-01

*Nut, Kep No. 8-32

90-06563-00

*Pulley, Timing (deleted)

74-11035-02

*Pulley, Timing (added)

12-12446-00

*Clamp, Collar

74-11124-00

*Screw, Soc Hd Cap No. 6-32 x .38

90-08045-08

*Nut, Hex No. 6-32

90-08957-00

*Pushrod

74-11046-00

*Retaining Ring

90-09580-00

*Washer, Eccentric

74-11123-00

*Spring, Backstop

74-11426-00

VENDOR

|REF

USED ON

CODE

FIG

CODE]

PART NO. | NO.
3

00155

LA36-08A

Figure 5. Ribbon Drive Assembly

23/24

IPB-LA36

FIG

®]

&
ITEM

NO.
6—

DESCRIPTION
CARRIAGE ASSEMBLY

Eco

CUT-IN

VENDOR

DEC

70-09692

USED ON

PART NO.

00000

CODE

70-09692-00

*Carriage

74-11109-00

*Lever, Carriage Adjustment

74-11110-00

*Bushing, Eccentric

74-11107-00

*|dler, Carriage Ribbon, w/ldler

74-11577-00

*Washer, Flat No. 6

90-06653-00

*Retaining Ring

90-08528-00

REF
FIG

CODE|

PART NO. | NO.
3

LA36

00011

6 \@

5 \@

b
4

LA36-12

Figure 6. Carriaae Assembly

25/26

IPB-LA36

mnanau>
PARTS LIST

OLD DESIGN

NEW DESIGN

LA180-13

Figure 7.

Idler Gear Assembly

IPB-LA36

FIG

ITEM

NO.
7—

DEC

DESCRIPTION

Eco
70-09694|

PART NO. | 00000

IDLER GEAR ASSEMBLY

70-09694-00
74-11420-00

*Bracket, Gear

*Gear, 48 Tooth

12-11656-00

*Tube, Idler (deleted)

74-11424-00

*Screw, Phl Pan Hd No. 8-32 x 1.00 (deleted)

90-06043-01

LA36
LA36

00223
5

*Washer, Flat No. 8 (deleted)

90-06666-00

LA36

00223

*Washer, Split Lock No. 8 (deleted)

90-06690-00

*Nut, Hex No. 8-32 (deleted)

90-06561-00

| LA36
00223
LA36
00223

*Standoff, Gear (added)

74-16219-00

LA36
00223

*Screw, Phl Truss Hd No. 8-32 x 1/2 (added)

90-06039-03

LA36
00223

*Washer, Flat No. 8 (added)

90-06668-00

LA36
00223

*Washer, External Tooth No. 8 (added)

90-08072-00

LA36
00223

IPB-LA36

CODE

FIG

CODE]

PART NO. | NO.
3

00223
4

USED ON

FIG

&
ITEM

DEC

NO.
8-

ECO

CUT-IN
DESCRIPTION

LA36

VENDOR
USED ON

PART NO. | 00001

CODE

TRANSFORMER ASSEMBLY (deleted)

70-09779-00

00138

A—H

16-11482-00

00138

*Power Transformer (deleted)

*Connector (P3) Pin Housing, 8 Pin Mate-N-Lok | 12-09340-01

*Terminal, Pin Contact

12-09378-00

*Terminal, Quick-Connect (deleted)

90-07919-00

00052

*Terminal, Quick-Connect (deleted)

90-07917-00

00124

*Connector (J1) Free-Hanging, 4 Socket

12-10821-04

00124

|REF
FIG

CODE]

PART NO. | NO.
2

Mate-N-Lok (deleted)

*Terminal, Socket Contact (deleted)

12-09379-00

00124

*Connector (J2, J3) Socket Housing AMP

12-10820-01

00124
00124

(deleted)
9

*Terminal, Socket Contact (deleted)

12-10820-02

*Terminal, Ring Tongue

90-07928-00

\\‘ N
—
fl

6
7

LA36-06

Figure 8. Transformer Assembly

29/30

IPB-LA36

FIG

&
ITEM

DEC

NO.
8A—

DESCRIPTION

LA36

PART NO. | 00138

TRANSFORMER ASSEMBLY
Transformer Assembly (60 Hz)
Transformer Assembly (50 Hz)
*Power Transformer (60 Hz)|

Eco
CUT-IN

ludes

*Power Transformer (50 Hz) ncludes

VENDOR
USED ON

CODE

CODE|

|REF

FIG
PART NO. | NO.
2A

70-09779-01
70-09779-02
Capaci

Lapacitors

JNKPS
MRLQ

16-12522-00

16-12521-00

*Connector (P3), Pin Housing, 8 Pin Mate-N-Lok | 12-09340-01

*Terminal, Pin Contact

*Connector (J2) Pin Housing, 3 Pin Mate-N-Lok | 12-10821-03

12-09378-00

*Connector (J1) Pin Housing, 4 Pin Mate-N-Lok | 12-09351-04

*Terminal, Pin Contact

12-09379-00

*Terminal, Ring Tongue

90-07928-00

*Cable Tie

90-07031-00

*Tubing, Heat Shrinkable

91-07253-09

*Tubing, Extruded

91-07244-00

*Terminal, Quick Connect

90-07970-00

T
T
|

o
8

r_g-===1
P3 ,

~—

I
\

——
5

— N\

b
—S—97 |

3
4

LA36-06A

Figure 8A. Transformer Assembly

31/32

IPB-LA36

FIG

°|

ITEM

DEC

NO.
9

DESCRIPTION

Eco

CUT-IN
LA36

PART NO. | 00166

D.C. MOTOR and ENCODER ASSEMBLY

70-09691-00
70-09780-00

*Motor, D.C.

*Encoder Base Harness Assembly

70-09777-00

*Screw, Phil Pan Hd No. 4-40 x .75

90-06015-01

*Clamp, Collar

74-11124-00

*Pulley, Timing

74-11035-01

*Screw, Soc Hd Cap No. 6-32 x .38

90-08045-08
90-08957-00

*Nut, Hex No. 6-32

*Disk Assembly

70-09778-00

*Clamp, Cable

90-07079-00

*Screw, Phi Pan Hd No. 8-32 x .31

90-06036-01

*Washer, Split Lock No. 8

90-06090-00

*Washer, Flat No. 8

90-06661-00

*Terminal, Strip Tie Down

90-07004-00

*Capacitor (.01 MFD)

10-01010-01

*Jumper

70-10001-09

* Jumper

70-10001-10

*Jumper

70-10001-07

*Jumper

70-10001-05

*Screw, Phil Pan Hd No. 6-32 x .18

90-08020-01

*Washer, Ext Tooth No. 6

90-07649-00

*Decal, Ground

36-12680-00

*Dust Cover, Encoder

74-11416-00

VENDOR
USED ON

CODE

REF
FIG

CODE]

PART NO. | NO.
3

LA36-18

Figure 9. D.C. Motor and Encoder Assembly

33/34

IPB-LA36

FIG

°l

&
ITEM

DEC

NO.
10—

DESCRIPTION
CAPACITOR HARNESS ASSEMBLY

PART NO.

Eco
CUT-IN

VENDOR

70-09895 | USED ON

00000

CODE

FIG

CODE|

70-09895-00

*Connector, P2, Pin Housing, 8 Pin Mate-N-Lok | 12-09340-01

*Terminal, Pin Contact

12-09378-00

*Connector, Solderless

90-07928-00

*Connector, Solderless

90-07926-00

*Tie Wrap

90-07031-00

*Tie Wrap, Screw Down (deleted )

90-07033-00

PART NO. | NO.
2,2A

:)-(';\13861

REF

LA36-05

Figure 10. Capacitor Harness Assembly

35/36

IPB-LA36

FIG

ITEM

NO.

DESCRIPTION

11—

CABLE ASSEMBLY (LA36 Keyboard) (deleted)]

ECO

CUT-IN

DEC

70-10000

USED ON

PART NO.

00000

CODE

70-10000-00

LA36

VENDOR
CODE]

REF
FIG

PART NO. | NO.

A—H

00136
1

*Cable, 24 Conductor (No. 22 AWG)

17-00011-01

*Housing, Termination Berg

12-10918-15

*Socket, Crimp

12-10089-07

*Label, (THIS SIDE UP)

36-11567-00

*Strain Relief

12-11166-00

*Connector, Solderless (deleted)

90-07917-00

*Connector, Solderless (added)

90-07970-00

*Tie Wrap

90-07031-00

00136

LA36

—

S
S

2
3

LA36-16

Figure 11. Cable Assembly (LA36
Keyboard)

37/38

IPB-LA36

FIG
&

ITEM

NO.
11A—

DESCRIPTION

Eco
CUT-IN
LA36

USED ON

PART NO.

00136

CODE

CABLE ASSEMBLY (LA36 Keyboard)

70-11519-00

*Cable, 24 Conductor (No. 22 AWG)

17-00011-01.

*Connector, Housing 44 Pin Berg

12-10918-15

*Terminals, Socket Crimp

12-10089-07

*Strain Relief

12-11166-00

*Label (THIS SIDE UP)

36-11567-00

*Tie Wraps

90-07031-00

|REF
FIG

CODE|

PART NO. | NO.

J-R.S

12A
13A

VENDOR

DEC

-U
S

1|3
IE

s2l e

1 (S
N

LA36-16A

Figure 11A. Cable Assembly (LA36 Keyboard)

39/40

IPB-LA36

FIG

ECO

CUT-IN

ITEM

DEC

NO.

DESCRIPTION

12—

KEYBOARD BEZEL ASSEMBLY (deleted)

70-09750

PART NO. | 00001
70-09750-01

LA36

VENDOR
USED ON

CODE

|REF
FIG

CODE]

PART NO. | NO.

EFGH

00163
1

*Bracket, Bezel

74-11427-01

*Spacer, Hex No. 8 x 1.00

90-09285-00

*Spacer, Hex No. 8 x .75

90-07868-00

*Nut, Kep No. 8-32

90-06563-00

*Switch, Rocker (DPST)

12-11621-00

*Switch, Rocker (3 Position)

12-11732-00

*Washer, Split Lock No. 6

90-07801-00

*Screw, Phl Pan Hd No. 6-32 x .31

90-06021-01

*LKO2 KEYBOARD ASSEMBLY

LK02-00

EFGH

EFGH (See IPB Manual EK-LKO02-IP-)

LA36-14

Figure 12. Keyboard Bezel Assembly

41/42

IPB-LA36

2080020

PARTS LIST

LA36-14A

Figure 12A. Keyboard Bezel Assembly

IPB-LA36

FIG

CUT-IN

ITEM

NO.

12A—-

ECO

DESCRIPTION

VENDOR

DEC

LA36

USED ON

PART NO.

00163

CODE

KEYBOARD BEZEL ASSEMBLY

70-09750-01

KEYBOARD BEZEL ASSEMBLY (added)

70-09750-03

*Bracket, Bezel

74-11427-01

*Bracket, Bezel (added)

74-11427-03

*Spacer, Hex No. 8 x 1.00

90-09235-00

00247

1A
1A

NPQR

00247

*Spacer, Hex No. 8 x .75

90-07868-00

*Nut, Kep No. 8-32

90-06563-00

*LK02 KEYBOARD ASSEMBLY

LK02-00

J—R,S

*Control Panel Cable

70-08612-OK

J—R,S

*FRONT CONTROL PANEL ASSEMBLY

70-11525-00

J—R.
S

**Keycap Set

12-12287-E3
54-11727-00

**Front Control Panel Assembly

*Switch, Rocker (DPST)

12-11621-00

*Grommet

90-09713-01

*Screw, Phl Pan Hd No. 6-32 x .31 (deleted)

90-06021-01

00205

*Washer, Split Lock No. 6-32 (deleted)

90-07801-00

00205

*Harness Clip

90-08340-00

*Jumper

70-10001-05

*Washer, External Tooth No. 8

90-08072-00

*Decal, Ground Symbol

36-12680-00

*Washer, Flat Nylon No. 8

90-06708-00

*KEYBOARD CABLE ASSEMBLY

70-11519-00

See Note

*Spacer, No. 8 x .375 (added)

90-06802-00

00205

* Jumper, Interlock (added)

70-10001-13

00219

Note: This Assembly formerly installed under

Figure 1A. (Per ECO LA36-00219)

IPB-LA36

PART NO. | NO.

FIG

CODE|]

NPQR

REF

(See IPB Manual EK-LK02-IP-)

CUT-IN

ITEM

DEC

NO.

DESCRIPTION

PART NO.

13—

KEYBOARD BEZEL ASSEMBLY (deleted)

70-09750-02

(With Cursor Control)

VENDOR

70-09750 | USED ON
00001
LA36

CODE

|REF
FIG

CODE]

PART NO. | NO.

ABCD

00163

*LKO3 KEYBOARD ASSEMBLY (deleted)

LKO03-00

LA36

ABCD

(See IPB Manual EK-LKO3-IP- )

A—H

(See IPB Manual EK-LKO02-IP-)

00136

*LK02 KEYBOARD ASSEMBLY

LKO02-00

*Cable, Keyboard

70-08612-0D

**Cable, 16 Conductor

91-07738-00

**Connector, Dual In Line 16 Pin

12-10722-00

*Bracket, Bezel

74-11427-02

*Spacer, Hex No. 8 x 1.00

90-09825-00

*Spacer, Hex No. 8 x .75

90-07868-00

*Nut, Kep No. 8-32

90-06563-00

*Switch, Rocker (DPST)

12-11621-00

*Switch, Rocker (3 Position) (deleted)

12-11732-00

ABCD

LA36

00136
12

*Washer, Split Lock No. 6

90-07801-00

*Screw, Phl Pan Hd No. 6-32 x .31

90-06021-00

LA36-15

Figure 13. Keyboard Bezel Assembly (W/Cursor Control)

45/46

IPB-LA36

)

d020020

PARTS LIST

LA36-15A

Figure 13A. Keyboard Bezel Assembly (w/Cursor Control)

IPB-LA36

FIG

&
ITEM

NO.

13A—

ECO
CUT-IN

DESCRIPTION

KEYBOARD BEZEL ASSEMBLY

VENDOR

DEC

LA36

USED ON

PART NO.

00163

CODE

70-09750-02

REF
FIG

CODE|

PART NO. | NO.

JKLM

J-R,
JKLM

(See IPB Manual EK-LK02-1P-)
(See IPB Manual EK-LKO3A-IP-)

(With Cursor Control)

2
3

*K02 KEYBOARD ASSEMBLY
*LKO3A KEYBOARD ASSEMBLY

*Bracket, Bezel

74-11427-02

*Spacer, Hex No. 8 x 1.00

90-09285-00

*Spacer, Hex No. 8 x .75

90-07868-00

*Nut, Kep No. 8-32

90-06563-00

*Cable (Keyboard to Cursor)

70-08612-0D

*Cable (Control Panel to Keyboard)

70-08612-0K

*FRONT CONTROL PANEL ASSEMBLY

70-11525-00

**Keycap Set

12-12287-00

**Front Control Panel Assembly

70-11727-00

*Grommet

90-09713-01

*Switch, Rocker (DPST)

12-11621-00

*Screw, Phl Pan Hd No. 6-32 x .31 (deleted)

90-06021-01

00205

*Washer, Split Lock No. 6 (deleted)

90-07801-00

00205

*Harness Clip

90-08340-00

LK02-00
LKO3A-00

*Jumper

70-10001-05

*Washer, External Tooth No. 8

90-08072-00

*Decal, Ground Symbol

36-12680-00

*Washer, Flat Nylon No. 8

90-06708-00

*KEYBOARD CABLE ASSEMBLY

70-11519-00

See Note

*Spacer, No. 8 x .375 (added)

90-06802-00

00205

*Jumper, Interiock (added)

70-10001-13

00219

Note: This Assembly formerly installed under

Figure 1A. (Per ECO LA36-00219)

IPB-LA36

11A

FIG

ECO
CUT-IN

ITEM

DEC

| NO.
14—

DESCRIPTION

BCOS-F

PART NO. | 00001

CABLE ASSEMBLY (BCO5SF Interface) (deleted) | BCO5F-15

LA36

VENDOR

USED ON

CODE

REF

FIG

CODE]

PART NO. | NO.

ABEF

00165

*Cable, 4 Conductor (No. 22 AWG)

91-07706-00

*Connector (P1, P2) Pin Housing, Mate-N-Lok

12-09340-01

*Terminal, Pin Contact

12-09378-03

DEC

2
3

/
fl

=G5

Ny
g

r;l

LA36-17

Figure 14. Cable Assembly (BCOS5F Interface)

49/50

IPB-LA36

APPENDIX C

REFERENCE DATA

C.1
ABBREVIATIONS
The abbreviations used in this manual are listed in Table C-1.

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-1

Table C-1

Glossary of Abbreviations

2SB

Two Stop Bits

AKO

Any Key On

AMP

Amplifier

Address Register

BCD

Binary Coded Decimal

BEL

Bell

Backspace

BUF

Buffer

BUFF

Buffer

C/B

Carry/Borrow

CB RAM

Character Buffer Read Access Memory

CBA

Character Buffer Address

CG ROM

Character Generator Read Only Memory

CHAR

Character

CLK

Clock

CLR

Clear

Centimeter

CNTR

Counter

COL

Column

COL HI

Column High

COL LO

Column Low

CONTROL RAM

Control Read Access Memory

CRAM

Control Read Access Memory

CTRL

Control

D/A

Digital to Analog

DAC

Digital to Analog

DEC

Decoder

DIR

Direction

Down

DRVR

Driver

ENB

Enable

Error

F/F

Flip Flop

FIFO

First In/First Out

High

HDE

Head Drive Enable

INC

Increment

INIT

Initialize

IPS

Inches Per Second

C-2

Table C-1

Glossary of Abbreviations (Cont)

KBD

Keyboard

KBH

Keyboard Hold

kHz

Kilohertz
Low

LCV

Last Character Visibility

Line Feed

LSB

Least Significant Bit
Meter

MH:z

Megahertz

Millimeter

MPC

Microprogrammed Controller

Microseconds
Milliseconds

MSB

Most Significant Bit

MUX

Multiplexer

Number Of Bits

Nanoseconds

POS HI

Position High

POS LO

Position Low

POS MD

Position Middle

POS

Position

POSIT

Position

PRINT Timer
Read or Register

RAM

Read Access Memory

RCV

Receive

RCVR

Receiver

RD ADR

Read Address

Read or Register

Receive Data

REG

ROM

Read Only Memory

Status

SYNC

Synchronize

TACH

Tachometer

TTL

Transitor To Transistor Logic

UART

Universal Asynchronous Receiver Transmitter

VREF

Voltage Reference

Table C-1

Glossary of Abbreviations (Cont)

Word Count

WD CNT

Word Count

WT ADR

Write Address

Read Access Memory Transmit Data

XMIT

Transmit

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

J5-4

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

E584 or E614

E499,E21-2

Solenoids

MPC3 BMBOO

Buffered Memory Bit O

E31-15,E15-15

MPC3 BMBOI

Bufiered Memory Bit 1

ES8-5 or E61-5

E49-5,E21-5
E31-14,E15-14

MPC3 BMBO02

Buffered Memory Bit 2

ES58-6 or E61-6

E49-3, E21-8
E31-13,E15-13

MPC35 BMBO3

Buffered Memory Bit 3

E58-7 or E61-7

E49-1,E21-11
E31-11,E15-11

MPC3 BMB04

Buffered Memory Bit 4

E58-8 or E61-8

E54-13, E46-23
E50-15

MPC3 BMBO05

Buffered Memory Bit 5

E58-9 or E61-9

E54-11, E46-22
E50-14

MPC3 BMBO06

MPC3 BMBO7

Buffered Memory Bit 6

Buffered Memory Bit 7

E58-10 or

E549, E53-1

E61-10

E46-21, E50-13

E58-11 or

E54-5, E53-2

E61-11

E46-20

MPC3 MBOO

Memory Bit 00

E58-4 or E614

MPC3 MBO1

Memory Bit 01

E58-5 or E51-5

—

MPC3 MBO02

Memory Bit 02

E58-6 or E61-6

—

MPC3 MBO3

Memory Bit 03

E58-7 or E61-7

—

MPC3 MB04

Memory Bit 04

E58-8 or E61-8

—

MPC3 MBO5

Memory Bit 05

E58-9 or E61-9

—

Table C-2
Mnemonic

MPC‘3 MBO06

Signal Glossary (Cont)

Definition

Memory Bit 06

Source

Destination

E58-10 or

—

ES8-11 or

—

E61-10

MPC3 MBO07

Memory Bit 07

E61-11
MPC4 CLR BEL

Clear Bell

E449

E36-3

MPC4 CLR C/B

Clear Carries or Borrows

E44-16

E11-13

MPC4 CLR DA

Clear Data Available

E44-2

E60-11

MPC4 CLR HDE

Clear Head Drive Enable

E44-13

E39-11,E30-11

MPC4 CLR INIT

Clear Initialize

E44-17

ES1-1

MPC4 CLR KBH

Clear Keyboard Hold

E44-1

ES1-10

MPC4 CLR 568

Clear 568

E44-6

E15-23,E314
E304

MPC4 CS00

Clocked Selector 04

E46-1

E42-1

MPC4 CSO01

Clocked Selector 04

E46-2

E42-2

MPC4 CS02

Clocked Selector 04

E46-3

E42-13

MPC4 CSO3

Clocked Selector 04

E46-4

E374

MPC4 CS04

Clocked Selector 04

E46-5

E37-5

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 CS13

Clocked Selector 04

E46-13

E44-18, 19

MPC4 CS14

Clocked Selector 04

E46-14

E42-5

MPC4 CS15

Clocked Selector 04

E46-15

E37-1, E42-3

MPC4 CS16

Clocked Selector 04

E46-16

—

E37-2,E37-13
E424

MPC4 CS17

Clocked Selector 04

E46-17

E534

Table C-2

Signal Glossary (Cont)

Mnemonic

Definition

Source

Destination

MPC4 LOAD CBA

Load Character Buffer Address

E444

E52-9

MPC4 LOAD D/A

Load Digital/Analog

E44-10

E14-9

MPC4 MAX

Maximum

E23-6

E31-5,E144,5,
12,13

MPC4 REGO:3

E32-2,3,6,7

E524,5,12,13
E38-1,5,9,10

MPC4 S000

Selector O

ES0-1

E22-2

MPC4 S001

Selector 1

E50-2

E27-2

MPC4 S002

Selector 2

E50-3

E21-3

MPC4 S003

Selector 3

ES04

E31-9

MPC4 S004

Selector 4

ES0-5

E15-9

MPC4 SET BEL

Set Bell

E44-9

E364

MPC4 SET HDE

Set Head Drive Enable

E44-11

E39-10

MPC4 SET HOLD

Set Hold

E44-15

E404

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

E324

MPC4 +1 REG

Increment Register

E44-3

E32-5

MPCS5 CLK

Clock

E64-5,12

E46-18, 19,
E29-10, E49-13

MPCS5 S.I.

Serial In

E66-6

ES55-20

MPCS 1.184 us

1.184 us

E13-12

E37-10, E13-1,
E64-9,E7-13,

E9-3,11

MPC5 1.76 kHz

1.76 kHz

E68-11

C-7

E30-3, E59-3

Table C-2

Signal Glossary (Cont)

Definition

Mnemonic

Source

Destination

MPC5 4.8 kHz

4.8 kHz

E63-11

E26-14,E174

MPCS 19

E26-9

E67-5,E31-21, 22

MPC5 76 us

76 us

E26-11

E3-3,ES-3

MPCS5 208

208

E26-12

E40-10,E67-11,

E17-7,E15-7,
E31-19

MPCS 568

568

E30-5,6

E64-10,E94, 10
E13-14,E379

MPC5 592 ns

592 ns

E17-13

E20-1

MPC6 BEL

Bell

E19-1

E15-6

MPC6 BS

Back Space

E199

'E15-20

MPC6 CR

Carriage Return

E19-3

E25-13,E154

MPC6 DA

Data Available

E55-19

E31-7

MPC6 HS1:7

Head Select

E28-4 to 11 and

Head Solenoid

E334to 11

Drivers

MPC6 HT

Horizontal Tab

E19-7

E15-21

MPC6 KBH

Keyboard Hold

E51-8

E31-20

MPC6 LF

Line Feed

E19-6

E25-1,E15-5

MPC6 PNTABL

Printable

E33-11

E25-11,E31-1

MPC6 S.O.

Serial Qut

ES5-25

E29-12

MPC7 BORROW

Borrow

E12-3

E12-1,E15-22
E31-18

MPC7 CARRY

Carry

E7-6

E31-23

MPC7 COL INC
COUNT 0:2

Column Increment Count

E16-2,3,6

E28-19 to 21,
E33-19 to 21

MPC7 INC

Increment

E30-9

E15-3

MPC7 PTCOM +5 V

Print Timer Common

J1-U, V

J1-13,17
(R1,R2)

Table C-2
Mnemonic

Signal Glossary (Cont)

Definition

Source

Destination

MPC7 SUM

Sum

E1-6 (J1-B)

MPC8 BEL

Bell

RS8

J1-TT, J1-38

MPC8 HDE (HDEM)

Head Drive Enable

E39-8

J5-2

MPCS8 INIT

Initialize

E51-5,6

E11-2,E31-8

MPC8 LF1

Line Feed 1

E24-9

J1-1J

MPC8 LF2

Line Feed 2

E24-5

J1-P

MPC8 LF HOLD

Line Feed Hold

E29-6

J1-HH

MPC8 W.U.

Wake Up

Q9-C

E53-5,E10-12,
E36-1,J1-DD,
E14-1

P.T. COLL 1

Print Timer Collector 1

Q1-C (J1-21)

J1-Y (E34-2)

P.T.COLL 2

Print Timer Collector 2

Qz2-C (J1-25)

J1-CC (E35-2)

C-9

380

QUAD 2-INPUT NOR GATE

GND

IC-0013

1702A

8-BIT REPROGRAMMABLE ROM

PIN CONFIGURATION

A —-4 1

24— Vpp

Ay —2

23— vee

Ao —13

22— Vee

¥DATA OUT 1 ——{4(LSB)

21}— A3

¥DATA OUT 2 —5

20— Ag4

¥DATA OUT 3 —{6

19— Ag

¥DATA OUT 4 —7

18— Ag

¥pATA OUT 5 ——8

17— A7

*¥DATA OUT 6 —19

16— Vg6

¥pATA OUT 7 —{10

15— Vgg

¥pDATA OUT 8 ——{11(M.B)

14— CS

Vee —12

PROGRAM

*THIS PIN IS THE DATA INPUT DURING PROGRAMMING

2627P

A6-01 CHARACTER GENERATOR ALPHA

PACKAGE “A”

—

BENT LEADS

Index Marlg"\

o nannrnn

INDEX MARK

pguuuubuuuu

NOTCH

1C-0123

PACKAGE ““B”” — BRAZED LEADS

Notc

NN N

'cG{e1 ~
CS2 g2
CS3 O3
% 04
0; Os

24
hhVss
23 [ Cs,
22 [ CSg
21 [J Ao
20 [ A1

O3
7
Oy Os
Os dg

18 [J A3
17 O A4
16 [0 A5

Oy O

[]10

07 du
Vpp 12
13

19 [ A2

15 [7 Ag

14 [T A7
13 5 Ag
1C-0120

ul_JuVJULJU‘;IJUD‘

1C-0124

C-11

2627P

A6-01 CHARACTER GENERATOR ALPHA (Cont)

FUNCTIONAL BLOCK

DIAGRAM

0,0,0:-0,
0q O3 09 09
796
V504

0, O3

O Yy

CHIP SELECT
9

CSg

A
~

130——
2

TRI-STATE

Cs,

OUTPUT STAGES
A

SNe

-5 | Y
1

A
R

]

o B

CSg

512

> ',B~—-

ROM

Ag A7 Ag Ag Ay Ay Ay Ap Ag

NOTE: Choice of connection A or
B for each chip select

is available as a mask option.
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 Dy 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 M0 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.

)
4

NON-OVERLAPPING

16 X 4

ROM DECODER

}

9 fp2

MATRIX

OF STORAGE CELLS

2101

M2 (1)jo—2

;

2 oo

M3 (1)jo—

Mo (1)jo—>

_Al__AD

l13 11415 ]1
Dg

VCC=PIN 16

GND=PIN 08
|

w_R——-o[>——

\
1

}—

—
/

El\ual—o[/¥

|
MO

M3
IC- 3101

C-13

7400

QUAD 2-INPUT POSITIVE NAND GATE

7
7400

o— 03

09 —{

7400

10 —|ra00

12 ——|
13

—

7400

VCC=PIN 14

GND = PIN @7

7401

IC-7400

NAND GATE-QUAD 2-PIN OPEN COLLECTOR

Vee

L3211t

ollq |8

7] Ldu

~J)

NIFRIERIK;

GND

IC-0129

C- 14

7404

HEX INVERTER

POSITIVE LOGIC: Y=A
IC-o0Mn

7408

QUAD 2-INPUT POSITIVE AND GATE

POSITIVE

LOGIC:

Y=AB
IC-0044

C-15

7410

TRIPLE 3-INPUT POSITIVE NAND GATE

————

04
05

°3

09 ——

10
11

01
02

7410

08 10
11

—dig

-1

—Q,440

}12 01
12
02
A 7410

A
741 0]

VCC = PIN 14

GND
= PIN 97

Vee

1C -7410

BINARY SELECT

Vee

b — v1
\

vs |—

POSITIVE

GND

LOGIC: Y= ABCD

IC-0008

8
GND

OUT;UTS

IC-0009

7416

HEX INVERTER BUFFER/DRIVER

POSITIVE

GND

LOGIC: Y:=AB
IC-0012

7417

HEX BUFFERS/DRIVERS

DpBpBmdpbadni
1A

POSITIVE

GND

LOGIC: Y=A
1C-0057

VCC
aKQ

3KQ

2KQ

5OUTPUT Y

INPUT AO—¢

2KQ

'3
Component

values shown are

-OGND

nominal
1C-0056

C-17

7420

NAND GATE-DUAL 4-INPUT

Vec
e

/30127

—— 0.770 MAX ———»~

olelelolclolo

missimiaisEos
s

]

| S B SN B WD B GNNS B GEEN B G

g SN )

oJolelololole

KIS

7
@ND

IC-0128

1IC-0130

EAIERIR

‘2 4

IR RN

NAND GATE-QUAD 2 IN BUFFER, 14 PIN

[RUiaY
~~—

Lo p]

-3

~No

——

7437

IC-0126

C-18

7442

4-LINE-TO-10-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.

fg b—“
n

fg 01_0_
°)

fz p—
12

(—b3

fe P—

7442

A3 1p2

fg D_—s L DECIMAL
6

fq p—=— ( OUTPUT

BCD

INPUT< a

b 4

15
——4{ DO

VCC =

PlN 16

GND= PIN O8
IC-7442

7442
TRUTH TABLE

BCD

Decimal

Input

Output

£3

C-19

7474

DUAL D-TYPE EDGE-TRIGGERED FLIP-FLOP

TRUTH TABLE FOR

7474 STANDARD CONFIGURATION

(EACH FLIP-FLOP)

tnht1

Preset

Clear

D Input

1 Side

0 Side

Pin 4(10)

Pin 1(13)

Pin 2(12)

Pin5

Pin 6

High

Low

High

Low

High

Low

High

Low

High

Low

High

th = bit time before clock pulse.
tn+1 = bit time after clock pulse.

X = irrelevant

STANDARD CONFIGURATION

REDIFINED CONFIGURATION

PRESET

°02fp

PRESET

4 %56

—

401
D

7474

o—

0o|os

—C

Yoa

PRESET
13

09
LA

1}o08

—o0

7474

o[ 05

CLEAR

PRESET

CLEAR

1},05

1,09

7474

oPss

Hic

ofge

Tro

CLEAR

Vce: PIN 14

IC-7474

GND=PIN O7

C-20

7489

64-BIT READ/WRITE MEMORY

WRITE

MEMORY

ENABLE

éoz

ENB

12
—D3

11
M3(1)o—

10
—1D2

M2(1)

09
O——

06_1,,

mmoo 7

(—22 {ho

OUTPUTS

MO(1) 22—
A2 A1

SELECT (INPUTS)
MEMORY ADDRESS
VCC: PIN 16

GND=PIN O8
I1C-7489

7493A

ENB

OPERATION

Write (WR)

CONDITION OF OUTPUTS
Complement of Write Data Inputs into addressed memory location.

Read (ENB)

Reads complement of word stored in selected memory location.

Inhibit Storage

Complement of Data Inputs

Do Nothing

High

COUNTER ASYNCHRONOUS UP, BINARY

NN s

GND

A
Y3

RESET

ZERO

Vee

1 L_J1
I

L
3

J L
4

(TOP

J0J
L]
5

LOCATOR

VIEW OF IC)

C-21

IC-0100

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.

114 |15

FET-

pr———

74123

a2 —2d
B2

10
—

012
74123

12
o——

Tn
+5V=PIN
16
GND =PIN 8
IC-74123A

TRUTH

INPUTS

OUTPUTS

| L

N
NOTE:

TABLE

e eUy

H=high level (steady state), L= low level (steady state),

t = transition from low to high level,

high

to low levei,

low-level

pulse,

¢=transition from

_I'L
= one high-level

pulse,

LI
= one

X= irrelevant (ony input, including transitions).
1C-741238

C-22

74150

DATA SELECTOR/MULTIPLEXER

\=2 n ~ e4V]S

e LOW TO ENABLE

[
]

©T

[

DATA SELECT
+5V = PIN 14

GND =PIN 7

74150 TRUTH TABLE
2

7] -

o2
(=)

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

fi14
-y

ANnsAaana

-y

pV)

f13

fis

Ta E s Ts £

The 74154 4-Line to 16-Line Decoder decodes four binary-coded inputs into one of 16 mutuallyexclusive outputs when both strobe inputs (G1 and G2) are low. The decoding function is performed
by using the four input lines to address the output line, passing data from one ofthe strobe inputs with
the other strobe input low. When either strobe input is high, all outputs are high.

74154

—

BCD

INPUT

|—{ D2
22

FOR DECODING | — D1
DO

1 OF 16 MUTUALLY

EXCLUSIVE OUTPUTS
DECODED FROM BCD INPUT
WHEN BOTH STB1 AND
STBO ARE LOW

—

16 OUTPUTS

STB1

STBO

18
Notes For Demultiplexing:

+5Vv :=PIN 24

Inputs used to address output line.

GND=PIN 12

Data passed from one strobe input
with other strobe held low.

Either

strobe high gives all high outputs.
IC-74154

C-24

4-BIT BINARY COUNTER

2 DO

DATA

3 D1

RO(1) 11‘1
R1(1) 12 $

6 D3

R3(1)-‘—-¢

R2(1) 12

INPUTS

OUTPUTS

74161

CLEAR ———-J CLR
1

LOAD —QJLD
2

CLOCK ——— CLK
7

CNT EN

——

ENABLE P

ENABLET

CARRY
15 CARRY_
col—

CRY EN
GND = PIN 8
+5V = PIN 16

typical clear, preset, count, and inhibit sequences

for 74161

IMustrated below is the following sequence:

1. Clear outputs to zero.

2. Preset to BCD seven.
3. Count to eight, nine, zero, one, two, and three.
4.

Inhibit

CLEAR

PIN O1

{ASYNCHRONOUS)

LOAD

|
)

_'J

INPUTS

r—

enos |

DATA

a——

PINO3

—

PINO6

]
]

CLOCK

T
ENABLE

PIN10O

N [ N [ S |

W T

—

Rt (1)
PINI3

— L]

R2(1)

-_'L_———-r__——]u

|
'L
|
|

CLEAR

[o]

CARRY
PIN1S

R3(1)
PINI e e

PINI2

‘r

r_--l‘

OUTPUTS

PINIG

ENABLE P

PINO2

74161

INHIBIT

—

PRESET
IC-74161

74178

QUAD D-TYPE FLIP-FLOP WITH CLEAR

(4)
DO o—

TRUTH TABLE
INPUT | OUTPUTS
'n

'n01

R(1)R(O)

H
L

(1)
R

CLK OO)
CLEAR

L
H

th =Bit time before

clock puise.

tnt1=Bit time ofter

clock pulse.

(1)
R1

CLK (O)f—=
CLEAR

]

Bloz

R3(0)
12

=< {p2
DATA
INPUTS

= 1py

ramP)
14

R2(1) P

rR2(0) F—
, } OUTPUTS
D3 o-

(9)

CLOCK o—

CLEAR

R3]

(15)

(1)

—

[ |/

RO(1) ‘2_
RO(O) |- |

CLR

(10)

‘e (o (0)
CLEAR

R1(0) 84q

R2
(1)

R2] (11)

—

R1(1)

t-—-—w DO

(1)

QCLK (o)N—mo°
CLEAR

| ]

CLK

Pin(16)= VCC , Pin (8)=GND

7T,

IC-74175

C-26

COUNTER, SYNCHRONOUS UP/DOWN DECADE, 16 PIN

—> 1MSB

MSB }—— REG (NUMBER)

06 REG (NUMBER)

INPUTS | _O1 |

102 REG (NUMBER)

DATA

51 s
—

OUTPUTS

LSBF>— REG (NUMBER)
o

—— —

——qPreseT

—
— —{

Regqister number is
unique to

74190

product

line

05 lcnT DN EN
04

—TO CNT EN
14

CRY

TT|CNT CLK

|12

STATE

RIPPLE
CLOCK

VCC=P|N 16

GND:=PIN 08

typical load, count, and inhibit sequences for 74190
Hlustrated below is the following sequence:

s wn
=

74190

Load (preset) to BCD seven.

Count up to eight, nine (maximum), zero, one, and two.
Inhibit.

. Count down to one, zero (minimum), nine, eight, and seven.

PIN 11 PRESET

PIN 15
l

DATA

PINTO

_ I

PINO9

COUNT

PINOS DOWN
ENABLE

pINO4

COUNT
enape

PINO3
NO2

L
I

: I

—

[

—

|||

—

||
:

RE—

—

—_—

—

[

_———

()

o0 :

V7,1

I
8

;

o
|

]

I
0

lF——COUNT uP ———QFINHIBIT—-I

|
|
—

I
|

[

)

L
2

PINIS clock
==

| |

-= =

I |

CARRY = ===

RIPPLE

———

—

—_—

PINTZ sraTe

—

——

swos
P

PINS clock

COUNT

———

e —_ —_— —_— —_- —- — —_— — —= — - —

INPUTS

———

——] I

PIN O1

|
0

I
9

'.——coum DOWN —

W
LOAD

IC-74190

C-27

74193

SYNCHRONOUS 4-BIT UP/DOWN COUNTER

The 74193 Binary Counter has a individual asynchro-

nous preset to each flip-flop, a fully independent clear
input, internal cascading circuitry, and provides syn-

chronous counting operations.

typical clear,l00d,and count sequences for 74193

INustrated below is the following sequence:

1. Clear outputs to zero.

2. Load {preset) to 8CD 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
3

CRY BRW
09

R3OV

—103

OATA LN PP

741

INPUTS{ o4

15 oo

—

DATA

r2(1) F2&

o2 ) OUTPUTS

ro1 )}

CLR LD CUP CDN
N%ETEE S(E)%\S\E,E-J
5

[

PINt1

(04D

PIN 15

PIN O]

°IN10

| ‘L__________________________

pwos

e [

T\
____

[

Produce pulses equal to width of count pulses

when counting down, count-up input must be high.
during: Underflow (BORROW)
CLR input high forces all outputs low. CLR

overrides load, data and DN/UP inputs.

load input low. Output changes to agree with inputs

I I ] l'_] [_‘l l_] [_'

{

PINO7 R3 (1}

]

- =|

[

}

Select DN or UP clock while other s heid high.

l; ;

CLE AR

PRESET

| 0 '

ILLUSTRATED

—_——_———_———
— — —

SEQUENCE

independent of count pulses.

Preset to any state by applying input data with

—

PIN 13 ROKe

—

PINGE &2 (1) —_ ]___r
PIN 12 (A

Overfliow (CARRY)

;

)
_

——

[

R1(1)

When counting up, count down input must be high;

—_——_———

)

L T

NOTE

1. Clear overrides load, data, and count inputs.

| Jr"'__——_———"—""'—

_r|

OUTPUTS

|l______________________

PINO3 RO (1)
PINO2

NOTES:

PING VN
DOV

{ 14 T 1 ‘05 [04

PIN 14 CLFAR

—

- COUNTLP

0
)

— COUNT DOWN
I7

0119

UNIVERSAL ASYNCHRONOUS RECEIVER/TRANSMITTER

40393837 363534 3332313029

28 27 2625 24 2322 21

TOP VIEW

2
3 4

101112

14 1516

17 181920

AVAYAYAVATIVAY] WAVLVIVAVAVIVAVIVAVAVIYLY)
IC-0119

C-28

/4193

301

AN DIP OPERATIONAL AMPLIFIER

/Mird! - D)

)
COUAL 110 LINVE

SALANCE)

OOMPENSR7/Ien) | /!

S8 l COrMPEAISRTION)

7| v r

- JRIVERTING

/) PUT

L | euTrUT

V-

IVAUT

I VERTING

]

EFLRCE

1IC-0122

309

K REGULATOR

TERMINAL CONNECTIONS
PIN1 = INPUT
PIN2= OUTPUT

CASE= GROUND

C-29

IC-0168

Reader’s Comments

LA36 DECwriter 11
Maintenance Manual
Yolume 1
EK-1LA36-MM-001

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