Digital PDFs

EK-OLPQ8-TM-003

June 1980

150 pages

Original

55MB

view download

OCR Version

18MB

view download

Document:	LQP8/78 Printer Systems Technical Manual
Order Number:	EK-OLPQ8-TM
Revision:	003
Pages:	150
Original Filename:

OCR Text

EK-OLQP8-TM-003

LQP8/78 Printer Systems
Technical Manual

CAUTION

The carriage assembly removal/replacement procedures in this manual supercede all previous printings of this manual.

digital equipment corporation ¢« merrimack, new hampshire

1st Edition, June 1976
2nd Edition, February 1977
3rd Edition, September 1977
- 3rd Edition (Rev), June 1980

Thé 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:

PDP

DEC

DECtape

DECCOMM

DECUS

RSTS

DECsystem-10

DIGITAL

TYPESET-8

DECSYSTEM-20

MASSBUS

TYPESET-11
UNIBUS

10/80-15

CONTENTS
Page

N AW
N —

ek
ek
bk
ek
et
ek
ek

DESCRIPTION

e
INTRODUCTION . . .. ... ... ... ... e e e
e e
e
e
e
e
e
e
e
e
e
..
...
...
.
.
EQUIPMENT SUPPLIED
e e e
e
e
e
e
e
e
e
e
e
e
..
..
.
.
ON
PHYSICAL DESCRIPTI
e e e e
e
e
e
e
e
e
e
e
...
..
.
.
.
.
.
.
.
Printer Assembly
o
o
..o
.
.
.
.
.
.
Supply
Printer Power
LQPS8-E Controller . . . . . . ... ... ... e e e

e
. ... .. e .. P e
BCO3R Signal Cable
.. .. e e e e
BC80F-25 Interface Cable . . . . ...
e e
APPLICABLE DOCUMENTS ... ... ....... e
- PERFORMANCE SPECIFICATIONS . . . . . .« « o v v v v v

e e e e e e
e e e e e .
e e e SN
v v v oo o v s

1-1
1-1
1-3
1-3
1-5
1-5
1-5
1-5
TV
1-7

INSTALLATION AND CHECKOUT GUIDE

2.1
2.2
2.3
2.4
2.5
2.6
2.7

e e e 2-1
e e e e e e e
. ... ... ..... e
GENERAL
oo oo e 2-2
. . . . . . . o
UNPACKING AND INSPECTION
INSTALLING THE CONTROLLERMODULE . . . .. ... .. ... ... 2-2
INSTALLING THE BCO3R SIGNALCABLE . .. . .. ... ... ... .. 2-4
PAPER INSTALLATION/ALIGNMENT (Without Forms Tractor) . . . . .. 2-9
.. 2-10
.o
. . . . . . . . ..
PRINT DENSITY ADJUSTMENT
PRE-OPERATIONAL CHECKOUT . .. . . . . .. ... ... ... ... 2-10

CHAPTER 3

OPERATION

e e e 3-1
. . . . e
GENERAL
e e e 3-1
.. .. e
. ...
'OPERATING CONTROLS AND INDICATORS
e e 3-1
e e e e e e
... e
. . . . . ...
LOADING PAPER
. . . . . . . ... ... .. C e e e e e . 3-1
Using Paper Guide Cradle
34
Using Forms Tractor . . . . . . . . . .. .. ... .. ...
e e e e e e e e 3-11
e
CHANGING RIBBONS . . . . .
o v b e e oo 3-11
. . . . . . . . .
CHANGING PRINT WHEELS
. . . ... ... ... ..... 3-15
ENERGIZING THE PRINTER ASSEMBLY
NORMAL OPERATING PROCEDURE . . . . . .. ... ... .. ..... 3-15
e 3-16
. . . . . . . . . o oo b h
OPERATOR MAINTENANCE
. . . . . . . . oo .. 3-16
FORMS TRACTOR REMOVAL
SKIRT AND PLATEN REMOVAL . . . . ... ... ... . ...... .. 3-16
PAPER GUIDE CRADLE REMOVAL/INSTALLATION . . ... ... ... 3-17
PLATEN AND SKIRT INSTALLATION . . .. ... .. .. ... ... .. 3-19
e e e e 3-21
. e
EMERGENCY OPERATION . . . ..
. . . .. .. ... .. .. 3-21
.
ASSEMBLY
DE-ENERGIZING THE PRINTER

—O

bk ok ek ek et \O OO0 ~J O\ N

A WWWN

CHAPTER 2

EJJUJUJUJUJUJUJUJUJ.UJUJUJWU)UJUJ

Ln-bg»pow'w'w'wt\)?—-

CHAPTER 1

CHAPTER 4
4.1
4.2
4.3
4.4
4.5

PROGRAMMING

. ... ... .... e e e e e e e e e e e e e 4-1
GENERAL
CONTROLLER INTERFACE SIGNALS . .. .. .. e e e e e e e 4-1
e e e e e 4-4
IOT INSTRUCTIONS . . . . .. [P e
o oo 4-10
...
.
.
.
.
.
.
.
S
CONSIDERATION
PROGRAMMING
. P L. . 411
PROGRAMMING EXAMPLES . .. ...

CONTENTS (CONT)
Page

CHAPTER 6

TECHNICAL DESCRIPTION

INTRODUCTION . .. ...
.. ... O 5-1
GENERAL INFORMATION
. . . .. ... ... ... e e e e e e e e e 5-1
e e e e e e e e e 5-1
Logic Diagrams . . . . . . . . . . ... .... e
e 5-1
e e e
e
e
i
i
i
o
.
.
.
.
.
.
.
Complement
IC
e e e e e e e e e e 5-1
. . . . . . .e
Printer Interface Signals
. . . . . . .. e e e e e e e e e e e 5-4
Omnibus Interface Signals
. . . . . .. I e e e e e e e 5-4
PDP-8 Word Structure
DETAILED THEORY .. ...
. .. e e e e e e e e
e
e
e 5-5
Basic Printer Operation
. . . . . . . . ..e
e e e e . 5-5
Restore Printer and Clear DONE Flag (10T 6507) ............ 5-5
Read Status Register IOT 6505)
. . . . .. ... ... N
Write Status IOT 6506) . . . . . . . . . . .. e
e e e e e e e e 5-7
Print Character (IOT 6504)
. . . . . . . . . ... ... ... .. 5-8
Move Carriage IOT 6503) . . . . . . . . . o o v o v v i i 5-9
. . . . . ... ... .. e 5-10
Move Paper IOT 6502)
Read Data Buffer into Accumulator (IOT 6501) e e i e e e e e e e e 5-10
Skip on Done (IOT 6500)
. . . . . . . . . . ...e
e e e e e e e 5-10
SERVICE

e e e e e e e [
.. e
INTRODUCTION . .. ...
. ... e e e i e e e e e e e e
Scope

Maintenance Plan

. . . . . . . .. R

e e

o 13 |
6-1

6-1

e e e e e e e e e e e e e 6-1
.« v v v v v v e e e e e e
RESOUTCES
.. .. e e e e e e e e e e e 6-2
. . ...
PREVENTIVE MAINTENANCE
. .. . . . . ... ... ... ... 6-2
Preventive Maintenance Schedule
Materials Required . . . . . . . . . . .o oo - 6-2
Customer Performed Equipment Maintenance . . . . . . . . .. . . .. 6-2
. . . . . . . . . .. . . .. . .. 6-2
Field Service Preventive Maintenance

gy vy
T
e T
T
P

Jo e
e

. . . .. e ea e

e e

e e e e

6-2

o 1%
. ... ... P
Cleaning
6-3
e
e
e
e e e
Lubrication . . . . & o . i e e e e e e e e e e e
e e 6-6
DIAGNOSTIC FUNCTIONAL DESCRIPTION e e e e e e e e
oo 6-6
b
v
v
0
v
. . . . . . . . o o o o v o
Overall Performance Test
6-6
e
e
e
e
e
e
e
Controller Diagnostic Test . . . . . .. e
6-6
...
...
...
.
.
.
.
.
.
.
Printer Dynamic Diagnostic Tests . .
6-7
e
e
e
e
e
..
.
.
.
.
.
Diagnostic Load and Run Procedure
6-8
..
...
..
.
.
.
.
.
.
.
Printing
for
Manual Entry of Characters
Test . . . . . . . . . .. 6-8
Halting an In-Process Dynamic Diagnostic
. . . . . .. .. ... 68
Halt
After
Diagnostic
Restarting Dynamic
. . . . . . .. 6-8
Location
a
of
Contents
the
Modifying
for
Procedure
- 69
e e e
e
..
.
...
.
ISOLATION
FAULT
SECTION
FUNCTIONAL
6-9
..o
.
.
.
.
.
.
.
Descriptions
and
Tests
Specific
6-9
e
e
e
e
e
e
e
e
...
..
..
..
.
.
.
.
.
.
.
.
.
.
Isolation
Fault
e e 6-9
e e e e e i
i e e e e e e e
TROUBLESHOOTING . . . .
6-9
e
oo
..
.
.
.
.
.
.
.
.
Analysis
Initial
. . . . . . .. L0000 6-11
Alignment and Adjustment

—

Qo
D W —

ol e

TG
RERE RERE RERE RERE

Inspection

e NEP N

N TV S e

D W~

:w:wi»'wbo'w'wwwwwwwwi\)i\fi—

CHAPTER 5

CONTENTS (CONT)
Page

6.5.2.1
6.5.2.2

6.5.2.3
6.5.2.4
6.5.2.5
6.5.2.6
6.5.2.7
6.5.2.8
6.5.2.9
6.5.3
6.5.3.1
6.5.3.2

Print Wheel Home Sensor (Transducer) Alignment...........cccocoeeeeirnn. 6-35
ee etST 6-34
Removal and Replacement .................... et
6-37
Carriage Removal Procedure.........c.oooooiiiiiiiiiii
Carriage Replacement Procedure..........ccoooooiiiii 6-52

APPENDIX A

MODIFIED ASCII CODE FOR STANDARD PRINT WHEEL

APPENDIX B

POSITION OF CHARACTERS ON PRINT WHEEL

APPENDIX C

INTERFACE WIRING DETAILS

APPENDIX D

DETAILS OF INTEGRATED CIRCUITS ON LQPS8-E CONTROLLER

APPENDIX E

TROUBLESHOOTING FLOWCHART

APPENDIX F

LQPS-F SERIAL PRINTER

F.1
F.2

F.2.1
F.2.2
T

Print Wheel to Hammer Adjustment.........cccooecevvmeeimmeereeieiininininnnneeenn, 6-13
Platen to Print Wheel Alignment Procedure............ccooooininninn, 6-14
Card Guide Height and Position Adjustment............ccoooooiieniiinnn, 6-16
e 6-17
Ribbon Height Adjustment...........cooiiiiiiiiiiiini
Carriage Home Adjustment...................... ettt 6-19
Hammer Armature Gap Adjustments........cc.oceoeeiiiiiiiiiiiiniiineiinnnn, 6-20
- Platen Height Adjustment.........oceeuivieiiiiiniiine... 6-20
Paper Feed Adjustment .........ccccoooiiiiiiiiiiii 6-34

F.2.3

F.24
F.3
F.4
F.5

F.5.1
F.5.2

F.5.3
F.5.4
F.5.5
F.5.6
F.6

SCOPE ... e et e F-1
INTRODUCTION................TSPeee F-1
Equipment Supplied.........cceevvmiiieiiiinin T e ————..F-1
aaaan F-2
Physical Description......... eet
e s s, F-3
ettt
ee
et
General Specifications............e
F-4
i,
Applicable DOCUMENTS .....ccoiiiiiiiiiiiieeceee
|

PREOPERATIONAL CHECKOUT ..........ccouuen..e. et...F-4
FUNCTIONAL DESCRIPTION................... ee F-5
e eaia e, e. F-5
eteaeeeareeeraaeaaan
SERVICING............... et e et
TRSUUTOTRR F-5
e
General.........cooviviiinnnn. ereeeens ereneens
et ana reeeean F-6
e
e
e
e
e
Maintenance Plan ..............c...........
e ——————— F-6
———
e
TR
ennnnen.
FRU Spares and Tools.......ccccceeee
F-7
e
e
e,
eeee
DiagnostiCS ..ocuvuiiieniiiieeiireeri
F-7
e
e
e
TroublESHOOtING....ovueiiiii
F-8
renrrenasenns
..........eveieerteaierrareera
Replacement................
Module Removal and
EF-8
SUTTR
PO
T
TP
B
DETAILS..........
INTERFACE WIRING

FIGURES

\O 0o

aoabbhrdblUmoocddadbhprbi
LA

Figure No.

Title
Typical LQPS Printer SYSTEM ......ovvniiiiiiiiiii

—_ O

——

e 1-2

LQPO!1 Printer Without FOrms Tractor .......coovuviuiiiiiiiee

e, 1-6

Site Considerations for LQP8 Printer and Desk ..........cccccccvviiiiiiiiiiiiiiiiiiiiiiiiiineee, 2-1
Packaging of LQPS8 Printer System ..............cceeevveennnnee, B U ..2-3
Jumper Wires on LQPS-E Controller Module .................................................... ...2-4
RaiSING Printer ACCESS COVET.....iiuniiiiiiiiii
e
e e e e 2-5
View Showing Top Cover Release LeVer............vvvviviiiiiiiiiiiiiiiiiieieeeeee
e, 2-6
View Showing Power and Signal Cable ConnectionsS..........cc.cccueeeiiiieeeiiieeennnnnnnne, 2-7
Interconnection Diagram for Typical LQPS8 Printer System ............cccevviiviiiiiinnnnnn. 2-8

Paper AlIgnment HOLES .........iivniiniiii
i 2-9
Forms Tractor Clamp Assembly........cc.ooiiiiiiiiiiiii
e, 3-5

Forms Tractor Installation .........c.oooovvviiiiiiiiiiiiiiee
e s 3-6
Positioning of Platen Pressure Release Lever When Forms Tractor Is Installed.....3-7
Major Elements of Forms Tractor..............et
reans 3-8
‘Loading Paper Through Slot in Desk Top .....ccooviiiiiiiiiiiiiiiiii
e, 3-9

Loading Paper in Forms Tractor from Rear...............coooeiiiiiiiiiiiiniieeeecn 3-10
Ribbon Removal.........ooiiiiiiiiii
s 3-12

Inner Carriage Assembly Tilted Away from Platen........cccoevveveennens e ———————— 3-13
View Showing Print Wheel Motor Shaft and
- Print Wheel Alignment HOLE.......c..ooooviiiiiiiiii

Page

|
e, 3-14

CSKIrt REMOVAL ..c.uiiiiiiiiiiii e
e 3-17
Pressing Platen Latches............ e teerressteehiesatesate
s rere bt e
reeaareaesratesresnreeans e
—— 3-18

View Showing Paper Guide Cradle ...............coevveeeenne. es 3-19
Readying Platen for Installation .......ccooooeeiiiiiiiiiiiiii

e, 3-20

Platen INStalled..........oooiiiiiiiiicee et 3-21

Controller Interface Signals...........ccovevvvviiiiieiiieeeieeceee, e 4-2
LQPSR Bit Interpretation........ccccocvviiiiiiiiiiiiieiiciiieee
ee 4-2
e, 4-4

IOT Instruction FOrmat..........cccvvvviiviiiiiie
Programming Paper MOtION........oouoiiiiiiiee

e, 4-8

Programming Carriage Motion..................... et

eee ettt e eeeeett—reeererr e eerraaaaararaaaaanan, 4-9

Programming Printer Commands...............eS VPR RRORY 4-10
Programming Example NO. 1 ..o 4-11
Programming Example NO. 2 ... 4-13
Controller BIOCK DIagram ..............coooviiiiiiiiiiiie
e, 5-2

Waveforms for IOT 6507 (Restore FUNCLION) ......ovveieiee e 5-6
Waveforms for IOT 6505 (Read Status) ........... e
———— 5-7
Waveforms for IOT 6506 (Load Status) .........cccccoeviiiiiiiiiiicieccee
e, SRR 5-8
Waveforms for IOT 6504 (Print Character) ... 5-9

Waveforms for IOT 6503 (Carriage MOtION)....oveeoueeeeeeeeeeeeeeeeeeeeeeee e, 5-10
Waveforms for IOT 6502 (Paper MOtion).......ccccooeieiiiiiiiiiieeeeee
e 5-11

Carriage System Lubrication POINtS ..o 6-4
Carrier System Lubrication PoOints ..., 6-5
Platen Lubrication Points........ U
PR OPR OO P TP PTRPPPIRS 6-6
Printed Circuit Board Layout and Function Description...........ccccoeeeiiviiiiiiiniiiinnnnnn. 6-12

Multipurpose Alignment ToOL............cccocoiiiiiiiii 6-13
Print Wheel-to-Hammer Alignment PosSitions .........cccccceeviiiiiiii, 6-14
Platen-to-Print Wheel Adjustment................ et
———— e 6-15

Card Guide Height AdJustment......oooooiiiiiiiiiee

e 6-16

FIGURES (CONT)
Figure No.
6-9

6-10
6-11
6-12
6-13
6-14
6-15
6-16
6-17
6-18
6-19

6-20
6-21
6-22

Page

Title

Ribbon Height Adjustment............... e 6-18
Exploded View of Ribbon Lift Assembly ...................... e e 6-19
Carriage Home Adjustment ...e ——————— 6-20
SO P SUP P PPRORPPR 6-21
Hammer Gap Adjustments .........ccocoeviniieen, TSP
iiiii6-21
oooiii
...coo
......
Height
Platen
Adjusting
for
Eccentrics
6-34
iiiiinn
cocooii
.......
re.....
HardwWa
Adjusting
Feed
Paper
Exploded View of Carriage Assembly.........ccoioiimnnnniiin e nn6-36
Printer Showing Cover and Signal Cable Removed...........SR e 6-39
aan6-40
Printer Tilted on BacK........ccoovvvivmiviiiiiiiiiiiiiiiiiiiiiie ettt
Printer Showing Bottom Panel Removed ........ e ——————e ———————— 6-41
Bottom View Showing Connectors, Cables, Tie Wraps,

and Attaching HaTdWAaTe . .....oooeoeeriiiiiii

e 6-42

Bottom View Showing Connectors Removed ..........e ee, 6-43

Bottom View Showing Bottom Plate Removed ... 6-44
Bottom View Showing Carriage Assembly Positioned for Camage

ASSEMDIY PULLEY ACCESS....vtiieeeeieeieiiniitieire ettt 6-45
View Showing Pulley HOId-DOWN SCIEW.......cooviueirmeiemiiiiiiiiniiiiiies 6-46

feolesReslesiesResN@R-o > T

kll-b-b)l\)"—‘)-—‘r-'-l*—‘p—a o)
N

View Showing Carriage Assembly Bottom Pulley w1th Hold-Down Screw

UPP S PPTPPPPPPTPPPI PP 6-47
PP
T T
0
) 2 < s DUTTUTTUTT
128811
..coooviiiiii 6-48
.......
Screws.
Hold-Down
Rail
Slide
Showing
View
View Showing Top Slide Rail Disengaged from Clamp......... e T 6-49
View Showing Top Slide Rail Disengaged from Carriage Assembly .................... 6-50
View Showing Bottom Slide Rail Disengaged from Clamp and Rubber Bushing
OIS RP PR OPPRPT PP PP PRSP 6-51
s 10N L <L NUTTUTUTT TR
RS
from Slide Rails ....coovvviiviieeenn, 6-52
Removed
Assembly
Carriage
Showing
View

Modified ASCII EXAMPLE.....ccooiiiiieiiiiiii i A-2
st e e asas s eenes B-1
esir et esitetia
et eeeieen
Print WHEEl CaraCterS. . ceumnerueieneeerieeti
Interconnection Diagram for Typical LQP8 Printer System.....ccccoovviiviiiiinnininnnn C-2
LQP8 Troubleshooting FIoWchart ... E-3
UPPPRN F-2
LQPXX-CS Serial Interface Components.................. SO P TP
F-3
iiiiii
iiiriii
.ccoooi
.......
Diagram
on
Connecti
Cable
LQPXX-CS

Mother Board SWitCh SEttINES ..ocvvvueveevreeeiiiiieiiie e F-5
Functional Block Diagram .............. TP PO F-6
Self-Test Functional Test Printout ...............c..ocooee errerer e F-9
TABLES

Table No.

Title

Page

LQPS Printer SYSTEIMS ....ccovuiiiiiiiiireiiiiire ittt 1-1
Equipment Supplied.........ccooiiiiiiiiniee 1-3
Standard Print Wheel Fonts Available from DIGITAL ... 1-3
1-4
Special Order Print WREelS.........oovriiiiiiiiii
ADPPLICable DOCUMENTS ....cviveeiiiiiiiiteiteee e 1-7
LQPS8 Performance Specifications .........occveenimiiiiiiiiis RUUTRS 1-9
“Operating Controls and Indicators ... 3-2

vil

TABLES (CONT)
Table No.
3-2
4-1

4-2
5-1
5-2

6-1
6-2

6-3

C-1
C-2
E-1
F-1

F-2

Title

Page

Operator Maintenance Chart...............ooooveiiiiii

e, 3-16
Bit Description for LQPSR ......cccooooviiiviiiiiiieeeieiin, ety eenseerrert
et e rrenraeas JUUT 4-3
Functional Description of IOT Instructions............cceevvvvuvvnnn... JE P 4-5
Controller IC Complement.......................SUTT e 5-1
Printer Interface Signals....................ecvvvnennn. T TSR 5-3

Recommended LQPS Field Service Branch Spares........... s 6-1
Catastrophic Failure Troubleshooting Chart............... SO 6-10

Degraded Print Quality Troubleshooting Chart..............cccooe
.. e

———— 6-22
Pin Assignments on LQP8-E Controller Module Connector J1....vvorveernnnn... C-3

Pin Assignments on Power Supply Connector P4........................ UTSUTRRRRR C-4
LQP8 System Problems..............ccccooeeie.... eteere e e e onns e traa e et s s tseennenreneanes E-1
Equipment Supplied with the LQPXX-CS ......... O
SO TR F-1
Recommended FRU Spares and Tools for the LQPXX CS .................................. F-7

viii

CHAPTER 1

DESCRIPTION

1.1

INTRODUCTION

This manual contains both user and field service information for the LQPS8 Printer System. Each

system is comprised of: an LQPO1 serial printer (with forms tractor), an LQPS8-E controller, a power

supply, an enclosed metal desk, signal cabling, and accessories (Figure 1-1).

The LQP8 /78 (i.e., LQP78) printer is interfaced to the VI78 DECstation processor-display unit via the
BCS80F-25 interface cable. Unlike other versions of the LQPS8 systems, the LQP8/78 printer does not
contain a controller. Other than these differences, both printer systems are identical in operation and
performance.

The LQP8 Printer System is designed primarily for use with the PDP-8 family of positive bus computers. The LQPS8 uses a lightweight, plastic print wheel as the basic printing mechanism for highquality alphanumeric and graphic reproduction. The printer is capable of obtaining a print speed of up
to 45 characters per second.

There is no keyboard on the LQPOI1 printer. In a normal word processing application, mesSages are
typed on a separate keyboard for display and subsequent editing on a video terminal. The edited
message is then transmitted from the word processor memory to the LQPOI for hard copy printouts.

Table 1-1 lists the model designations for the LQP8 Printer Systems. Models LQP8-EA and LQP8-EB
are identical except for the wiring of the input power transformer in the power supply. Model LQP8-

EA operates on 115 Vac, 50 or 60 Hz; Model LQP8-EB operates on 230 Vac, 50 or 60 Hz. The power

supply is prewired at the factory (prior to shipment) for either 115 or 230 Vac operation.

" Table 1-1 LQPS Printer Systems
Model

- Consists Of

1.2

LQPO1-A Printer, Power Supply and Desk

LQPS-EA
LQPS8-EB

LQP8-E Controller (M8366 plus BCO3R-25)

LQPO1-B Printer, Power Supply and Desk

Input Power
|

115 Vac, 50 or 60 Hz
|

230 Vac, 50 or 60 Hz

LQPS8-E Controller (M8366 plus BCO3R-25)

EQUIPMENT SUPPLIED

Table 1-2 lists the quantity and DIGITAL part number for each item supplied with the LQPS.

1-1

LQPO1 PRINTER

FORMS TRACTOR

7834-29

TYPICAL PRINT WHEEL

7834-32

7834-1
BCO3R FLAT SIGNAL CABLE

[

AC/DC POWER SUPPLY

'834-30
7834-5

LQP8-E INTERFACE CONTROLLER
-

RIBBON CARTRIDGE

Figure 1-1

Typical LQP8 Printer System

1-2

Table 1-2

Quantity

Part No.

1 each
1 each
1 each
] each
1 each
1 each

Printer
Forms Tractor
Power Supply
Desk
Controller
I/0 Cable

30-13086-00
30-13087-00
30-13094-00
34-13093-00
LQPS8-E
BCO03R-0-0

| ==--

Paper, Fanfold, 15-inWide

36-13256-04
36-13259-02
36-13259-01

Print Wheel (Courier 72)
Ribbon Cartridge, Cloth, Black
Ribbon Cartridge, Mylar, Black

1 each
|1 each
1 each

1.3.1

DIGITAL

Name

1 stack

1.3

Equipment Supplied

PHYSICAL DESCRIPTION
}

Printer Assembly

The model (LQPO1) printer is a modified Diablo Model 1345 HyType II Serial Impact Printer*. Itis a
rugged, compact unit featuring multiple-forms capability, letter quality printing, and minimum
maintenance. Unique machine design features eliminate most of the moving parts that are found in
‘

conventional stand-alone printers.

The printer uses a 96-character set printing element in either 10 or 12 pitch. Horizontal column spacing
is in increments of 1/120th of an inch (120 positions per inch), and vertical line spacing is in increments
of 1/48th of an inch (48 print positions per inch).

The typing ribbon is completely e’nélosed in a durable, non-smudge cartridge-type holder; it also snaps
easily in and out of place for easy replacement.

(approximately
Single-color cloth ribbons (approximately 1 million impressions) and mylar ribbons
us loop, mylar
continuo
200,000 impressions) are standard DIGITAL accessories. Cloth ribbons are

ribbons have an end-of-ribbon sensor to stop the printer when the sensor is activated.
The inner carriage assembly tilts away from the platen for easy access and exchange of print wheels.
There are four print wheels that are standard DIGITAL accessories (Table 1-3). Table 1-4 lists the
print wheels that are available on request. The 7-bit modified ASCII code (in octal) for programming
the print wheel characters is detailed in Appendix A.
*Diablo Systems, Inc., Hayward, California 94545

Table 1-3 Standard Print Wheel Fonts Available from DIGITAL
Pitch

Font
Courier 10
Pica 10
Elite 12
Courier 72

DIGITAL Part No.
36-13256-01
36-13256-02
36-13256-03
36-13256-04

10
10
k/j 12
10

1-3

T.able 1-4 Special Order Print Wheels*
Font Style

Pitch

Font Style

APL 10

10
10
10
10
10
10
10
10
12

Kana Gothic Pica 10
Manifold 10
OCR-A
OCR-B
OCR-B Kana
Pica Legal 10A
Prestige Elite Legal 12
Scandia Elite 12
|
UK Courier 10

|
British Pica 10
Courier Legal 10
Courier Legal 10A
Forms Gothic S-10
French Prestige Cubic
General Scientific 10
German Pica 10
Kana Gothic Elite 12

Pitch
|

10
10
10
10
10
12
12
10

*Available upon request,
Contact your DIGITAL/Diablo Sales Representative for samples of these print styles, or information on
unlisted print wheels.

Each print wheel is 7.62 cm (3 in) in diameter and resembles a daisy with 96 petals, one for each
character. All of the standard print wheels are directly interchangeable and easily snap in and out of
place in a matter of seconds.
|
-

The letter E is the home position for the print wheel; that is, E is the starting position of the wheel when
the printer is initialized (restored). The print wheel control logic computes the shortest distance and
direction of movement to place the next character to be printed in front of the print hammer. On

receipt of the first character, the print wheel rotates up to 3.14100 radians (180 degrees) in either
direction, depending on the selected character location, and then stops. The print hammer hits the
petal, with the result that the character is printed on the paper. On receipt of the next character, the
print wheel moves up to 3.14100 radians (180 degrees) in either direction from the first character
position and the printing process continues.
Print wheel velocity is a function of the distance to be traveled, with the wheel stopping prior to each
print hammer stroke. A 3-position hammer-intensity switch (under the access cover) permits manual
adjustment for variable font size and multiple-forms requirements.
v

Carriage movement permits printing in either direction (left-to-right or right-to-left) along the horizontal axis with equal speed and ease. By printing in the reverse direction, a carriage return is avoided,

resulting in a 15 percent increase in speed. With power off, the carriage can be moved manually along
the platen. When power is applied and the printer is initialized, the carriage automatically returns to its
leftmost (home) position.
|

Paper feed is controlled by a friction-fed platen that can be used with or without the forms tractor
option. If the forms tractor option is not used, a paper guide cradle is installed. In this configuration,

paper is loaded from the top side of the printer, around the platen. Paper movement can be forward
(upward) or backward (downward). Note that if the forms tractor option is installed, downward

motion 1s not possible. A platen position control lever provides the operator with the ability to adjust
for paper thickness and/or multiple forms.
|

When the forms tractor option is used, the paper guide cradle must be removed to facilitate installation. In this configuration, fanfold paper is loaded from the bottom of the printer, through a slot in the
desk, and onto the forms tractor. In this case, paper movement can only be in the forward (upward)
direction. The forms tractor accommodates single-sheet or multiple-form paper (up to six parts) with
standard 1.27 cm (1/2 in) hole spacing. The forms tractor option is mounted on top of the printer and
is driven by the paper feed drive train. The tractor is adjustable to any form from 4.45 cm (1-3/4in) to
|

38.10 cm (15 in) wide.

The operator control panel (Figure 1-2) contains two status indicators (PRINTER READY and END
OF RIBBON) and one pushbutton switch (PAUSE). When lit, PRINTER READY indicates the
printer is on-line and ready for printing. END OF RIBBON lights when the mylar ribbon is exhausted.
Pressing the PAUSE pushbutton lights the PAUSE lamp and causes the printer to complete all commands currently in process and then stop. This feature permits the operator to change print wheels or
to service exhaustible supplies such as ribbon and paper without having to power down the system.
When service is completed, the PAUSE pushbutton is pressed to extinguish the PAUSE lamp and
|

permit normal print operations to be resumed without losing any information.

in Figure 1-2 include: left and right bail arms for moving the
Additional operator controls shown
pressure release lever for paper positioning and line-up; and
platen
a
backward;
or
forward
paper bail
a platen position control lever for multiple-copy control. The right-hand platen knob can be pushed in
|

and adjusted for fine vertical paper movement.

Printer electronics and cable connections are located at the rear of the printer, below the ventilated
|

cover.

A paper guide rack assembly is permanently attached to the printer cover assembly (Figure 1-2). Two
other rack assemblies (upper and lower) are added to the printer when the forms tractor option is
installed (not shown). The rack assemblies facilitate better air circulation over the printer electronics
|

and also guide the paper properly to prevent paper jams.

1.3.2 Printer Power Supply

The printer power supply is a Diablo Model 1329 regulated supply, which is a self-contained unit that
measures 45.72 cm (18 in) long by 20.73 cm (8.16 in) wide by 8.31 cm (3.27 in) high (approximate
dimensions). The power supply is mounted in a metal enclosure inside the desk. An ac power cable on
the front of the supply connects the power supply to the main power source. An output power cable on
the rear of the supply connects the power supply to a 14-pin connector on the right rear side of the
printer. There are no power on-off indicators or switches on the supply. However, an external circuit
breaker is provided on the power control box inside the desk. Output dc voltages from the power
supply are: £15 Vdc and +5 Vdc.
1.3.3

LQPS-E Controller

The interface controller is a single M8366 quad module with TTL logic. It is installed on the PDP-8
Omnibus and connected to the LQPO1 printer via a 50-conductor BCO3R-25 flat cable. There are two
jumper selectable options: six jumpers for device 10T selection, and one jumper for printer
-

initialization (restore). The normal IOT device code is 50s.
1.3.4

BCO3R Signal Cable

The BCO3R cable furnished with the LQP8 Printer System is a standard 7.62 m (25 ft) DIGITAL
cable. A cable length of 15.24 m (50 ft) is available on special order.
BCS80F-25 Interface Cable

1.3.5
The BCSOF interface cable furnished with the LQP8/78 (i.e., LQP78) Printer System is a standard 7.62
m (25 ft) DIGITAL cable. It connects to the VI78 DECstation processor-display unit through the

parallel I/O plug on the rear interconnection panel.
1-5

PLATEN

PLATEN POSITION

PAPER

PRESSURE

PLATEN

BAIL

CONTROL

CENTERING

RACK

RELEASE

KNOB

ARM

LEVER

SCALE

ASSEMBLY

LEVER

PLATEN

KNOB
BAIL ARM

SKIRT

(PUSH IN)

I
’[.

|
1
|

]
|
]

‘

SKIRT

PLATEN
LATCH

ROLLER

PAPER
~

PLATEN

BALL

ACCESS

PITCH

TOP COVER

COVER

IDENTIFICATION

ASSEMBLY

OPERATOR
CONTROL PANEL

SCALE

Figure 1-2

LQPO1 Printer Without Forms Tractor

PLATEN
_
LATCH

7834-37

1.4

APPLICABLE DOCUMENTS

This manual and the Diablo Series 1300 HyType II Printer Manual must be used together for a complete understanding of LQP8 Printer Systems. The prime subject of this manual is the LQP8-E controller. However, in addition to the LQPS-E controller, this manual also includes sections covering
printer installation, operation, programming, and preventive maintenance. The prime objective of the
Diablo printer manual is the printer itself. That manual presents a detailed discussion of the print
mechanism and also covers detailed theory and maintenance.

Table 1-5 lists other DIGITAL documents that are applicable to LQP8 Printer Systems.

Detailed controller logic diagrams, wiring diagrams, and board layout are contained in the LQP8 Field

Maintenance Print Set (MP00098).

1.5

PERFORMANCE SPECIFICATIONS

Complete performance specifications for an LQP8 Printer System are listed in Table 1-6. Note that the
LQPS is a high-quality printer designed for light-medium duty application. Service agreements for this
device are available to cover field maintenance on typical applications. Time and materials service is
available for printer applications which exceed medium duty usage; that is, over 70 printing hours per
month or 10 million characters per month.

Applicable Documents

Table 1-5

Description

Title

Number

Series 1300 HyType II

‘Diablo 82403P

Printer, Maintenance
Manual

Model 1329 Power Supply, | Diablo 82003A

Maintenance Manual

Provides a detailed description of the

Diablo Series 1300 Printers. Also covers
installation, operation, theory, and
basic maintenance.

Covers description, installation, opera-

tion, theory, and maintenance of Model
1329 Power Supply. Also contains

detailed parts list.

*EB-04595 750200/0-19
PDP-8/A Miniprocessor
| 0425
Handbook

Introduction to the basic PDP-8/A
system. Describes internal design and

packaging; PDP-8/A operating and realtime systems; instructions for operating
and programming the PDP-8/A; the
PDP-8/A Omnibus; standard interface
hardware; the PDP-8/A semiconductor
memory, with read only memory (ROM)
programming instructions; PDP-8/A
core memory systems; and user information to plan and prepare for installation
of the PDP-8/A.

Table 1-5

Applicable Documents ( Cont)

Title

Number

PDP-8/A Miniprocessor

*EK-8A002-MM-001

Description

User’s Manual

Contains detailed description of PDP-8/A

miniprocessor. Also covers PDP-8/A
installation, Omnibus interfacing,
detailed theory of operation of CPU
and memories, I/O options, and power
supply. Concludes with detailed maintenance and troubleshooting informa-

tion, and complete print set.

PDP-8/E, -8/M, and

-8/F Small Computer

*018-00173-2546-S-09-100

Introduction to the basic PDP-8/E, -8/M,

and -8/F systems, with emphasis on the

Handbook

PDP-8/E. Describes internal design and
packaging, operating systems and software, programming, Omnibus interfac-

ing, peripherals, installation planning,

and I/O design.
PDP-8/E, -8/F, and

*EK-8E001-MM-004

A three volume series containing

-8/M Processor

detailed installation procedures, logic

Maintenance Manual

theory, and maintenance instructions.

Volume 1 deals with the basic computer;
Volume 2 covers internal bus options;
and Volume 3 is concerned with external bus options.

OS/8 Handbook

*DEC-S8-OSHBA-A-D

Describes the OS/8 Operating System

for the PDP-8/E computer.
DS310 Installation

Contains detailed information on the

EK-DS310-IN-000

Manual

installation and checkout of the DEC
DATASYSTEM 310 Word Processing

System.

Operator’s
Tutorial Manual

EK-TYSTM-TM-001

The Operator’s Tutorial Manual is used
together with a teaching diskette

(floppy) to provide programmed selfinstruction for the WPS-8 software
system. This includes: recording, edit-

ing, printout, file manipulation, and

other word processing functions.

1-8

Table 1-5 Applicable Documents (Cont)

Title

‘Number

System Reference

EK-TY8SR-RC-001
:
|

Guide

* Description
A pocket-sized summary of all the
features of WPS-8. Its purpose is to

provide quick, concise reminders about
system operation after completion of
training.

A technically oriented manual that provides more detailed explanations of

EK-TY&SR-RM-001
|

System Reference
Manual

features and functions than those
presented in the Operator’s Tutorial
|
Manual.

*Applicable manuals are furnished with the system at time of installation. The document number depends upon the
specific PDP-8 family processor.

LQP8 Performance Specifications

Table 1-6
Print Speed

‘

Up to 45 characters per second

Character Set
96 characters
Print Line
33.27 cm (13.1 in)

132 columns on 10 pitch
158 columns on 12 pitch

Paper Width
38.1 cm (15 in) maximum
Carriage Return
300 ms maximum

Tabulation

Horizontal tab in either right or left direction

Column Spacing
60 positions per inch

120 positions per inch selectable
|

Paper Feed

Up or down (without forms tractor); up only (with forms tractor)

1-9

Table 1-6 LQP8 Performance Specifications (Cont)
Line Spacing
48 positions per inch nominal
Paper Feed Speed
10.16 cm (4 in) per second plus 50 ms settling delay (typical)
Paper Skew

Movement from one line to any position on next line
Paper Feed Forms Thickness
|
Manual selection, up to 0.0686 cm (0.027 in)

AC Power Requlrements

115 Vac or 230 Vac + 10%, 50 or 60 Hz + 1 Hz

DC Power Requirements*
+ 5Vdc@ 4 A
regulated within 2%
+15Vdc @ 6 A peak
regulated within 5%

-15Vdc @ 6 A peak
100 W

regulated within 5%
(typical average)

Ribbon Element
Interchangeable cartridge with end-of-ribbon indicator for
mylar ribbons
Ribbon Type
Single-color cloth or film-base carbon (mylar)
Paper Feed Capability
Friction Feed
Adjustable Tractor Feed

Physical Characteristics (Printer)
Dimensions 59.06 cm (23.25 in) long X 34.37 cm (13.53 1n)
wide X 22.23 cm (8.75 in) high (without tractor)
X 26.91 cm (10.75 in) high (with tractor)
Weight (with tractor) 12.70 kg (28 1b)
Weight (without tractor) 12.25 kg (27 1b)

Physical Characteristics (Desk)
Dimensions 91.44 cm (36 in) long X 60.96 cm
(24 in) wide X 68.58 cm (27 in) high

Physical Characteristics (Power Supply)
Dimensions 45.72 cm (18 in) long X 20.73 cm
(8.16 in) wide X 8.31 cm (3.27 in) high

1-10

Table 1-6

LQPS8 Performance Specifications (Cont)

**Physical Characteristics (Printer, Desk, and Power Supply)
Dimensions (overall) 91.44 cm (36 in) long
X 60.96 cm (24 in) wide X 95.89 cm (37-3/4 in) high

Recommended Operating Conditions

Temperature
Humidity

'18° Ct024° C(65° Fto75° F)
40% to 60%

NOTE

Keep the system out of direct sunlight. Maintain the
recommended humidity range to prevent static
electricity.

Suggested Application

Not more than 70 printing hours per month or 10 million
characters per month

*Furnished by printer power supply.
**Excludes BCO3R signal cable. With forms tractor.

CHAPTER 2

‘

INSTALLATION AND CHECKOUT GUIDE

2.1

GENERAL

This chapter contains step-by-step instructions for unpacking the LQP8 Printer System and performing cabling and interconnections. The printer 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 at the top and bottom of the printer housing should not be obstructed. Adequate clearance must also be provided for servicing the unit (refer to Figure 2-1).
|
_

36.00"
(914.4mm)

AR i
(958.8mm)

24.00"

(609.6mm)

)
SERVICE
AREA
08-1719

Figure 2-1

Site Considerations for LQP8 Printer and Desk
2-1

2.2 UNPACKING AND INSPECTION
The LQP8 Printer System is normally shipped in two separate containers: one contains the LQPO1
printer, desk, and power supply and comes as an assembled unit; and one carton contains the LQPS-E
controller and the BCO3R signal cable. A shipping container inside the desk contains the forms tractor
option. The platen, paper guide cradle, ribbon cartridge, and print wheel are all installed in the printer
‘prior to shipment. No special instructions are needed and/or required for unpacking the controller or
the BCO3R signal cable. To unpack the LQPO1 items, proceed as follows:
I.

Cut the steel retaining straps securing the shipping carton and discard them (Figure 2-2).

Remove the top half of the slotted carton by sliding it upward and over the contents of the

shipping carton.
3.

Remove the poly bag.

4. Cut and remove the plastic strapping around the ends of the desk and remove the corner
supports from the desk.

Remove the shippng retainer bar (held in place by screws) from the desk feet.

Remove all shock-absorbing packing material from around the desk.

8.
9.

10.

Remove the printer/desk assembly from the shipping skid and position it in the desired

location. Adjust the leveling feet on the desk, as necessary, to level the entire unit.

Remove the filament tape that secures the desk doors. Then remove the two tie wraps secur-

ing the print head and carriage assembly (Figure 2-2).
Remove and unpack the forms tractor.

Make a visual inspection of the printer, desk, power supply, and other parts for possible

shipping damage. Check the enclosed packing list for lost or missing items. Report any
damaged or missing items to your local DIGITAL Field Service or Sales Office and to the
local carrier.
|
11.

If necessary, wipe all outer surfaces with a clean, soft, lint-free cloth to remove dust and

other foreign particles.

2.3 INSTALLING THE CONTROLLER MODULE
Before installing the controller module in the Omnibus, check the jumper wire connections on the
module (Figure 2-3). Jumpers W1 through W6 determine the device selection code, which can range
from 00s to 77; (except Interrupt 00s and Extended Memory 20 through 27s). In a standard configuration, 50z is the normal device selection code. This is represented by jumpers W1 and W3 being
soldered in place. To change the selection code, it is only necessary to change these jumper connections
to the desired configuration (from 00z to 77s).
|

When jumper W7 is installed, a printer restore operation occurs whenever a system INITialize pulse is

generated. This feature may be bypassed, if desired, by unsoldering and removing jumper W7. (Refer

to Chapters 4 and 5 of this manual for additional details concerning the printer restore operation.)

2-2

(9905735)

HALF SLOTTED CARTON

— (9905906)

TIE WRAP

POLY BAG

(9905128-08)

(9007032)

—

FORMS TRACTOR
(REMOVED SEE
STEP 4)

CORNER
SUPPORT

TIE WRAP

(9007032)

(9905737)
PLASTIC

STRAPPING —*
(99057 34)

‘\Loém DESK

CUSHIONED SHIPPING SKID
-— (9905907)
0]

RETAINER
BAR

08-1845

Figure 2-2 Packaging of LQP8 Printer System
2-3

7834-30

Figure 2-3

Jumper Wires on LQP8-E Controller Module

2.4 INSTALLING THE BCO3R SIGNAL CABLE
To install the signal cable, proceed as follows:
1.

Lift and remove the printer access cover, as shown in Figure 2-4.

Remove the platen (see Paragraph 3.10 for details).
.

Move the top cover release levers (Figure 2-5) fully forward (toward the control panel). This
enables the entire printer top cover to be removed for access to the printed circuit boards
(Figure 2-6).
|

Route the BCO3R signal cable through the printer cabinet as shown in Figure 2-7. Refer to

Appendix D for pin assignments for the power supply and connector cable.

2-4

Accsss

ACCESS

COVER

7834-39

CATCH

Figure 2-4

Raising Printer Access Cover

Plug one end of the BCO3R cable into the connector on printer module Logic 1 (Figure 2-6).
Plug the other end of the cable into the connector on the LQP8-E controller module. (Subsequently, the controller module will be connected to the Omnibus in the user system.)
NOTE
After installing the signal cable, check that the power cable connection is also secure (Figure 2-6). Then,
check that the printed circuit boards are seated properly. These boards are keyed for proper installation.

Make sure that the paper guide cradle (Figure 2-8) is installed.

TOP COVER
|
RELEASE LEVER

BAIL
ARM

PLATEN LATCH

7834-10

Figure 2-5

View Showing Top Cover Release Lever

Reinstall the printer top cover. (It will be necessary to move the top cover release levers to
seat the cover properly.)

Reinstall the platen and skirts (see Paragraph 3.12 for details).
Reinstall the printer access cover.

BCO3R

PRINTED

SIGNAL

CIRCUIT

CABLE

BOARDS

CONNECTOR
£

{

INTENSITY CONTROL

COVER OPEN

PLATEN LATCH

POWER CABLE CONNECTOR

SWITCH

*DO NOT FOLD CABLE

Figure 2-6

View Showing Power and Signal Cable Connections

7834-8

SEE DETAIL "A”

DETAIL "A”

SEE DETAIL "A”

i
DETAIL "A"

08-1844

Figure 2-7

Interconnection Diagram for Typical LQP8 Printer System

2-8

PAPER GUIDE CRADLE

ALIGNMENT HOLES

7834-4A

Figure 2-8

Paper Alignment Holes

2.5 PAPER INSTALLATION/ALIGNMENT (Without Forms Tractor)
Proceed as follows, using single-sheet lined paper (or substitute), to align the paper:
1.

If necessary, move the platen pressure release lever (Figure 1-2) away from the platen (to
increase pressure).

Pull the paper bail away from the platen.

Holding the paper aligned horizontally to provide the desired margins, insert it into the
printer over the rack assembly, and behind the platen. Adjust the platen position control
lever, as required (full forward for single-sheet paper).

Use the platen knob to roll the paper into the printer until it is approximately 5.08 cm (2 in)

above the paper bail.

2-9

If necessary, pull the platen pressure release lever forward and manually position the paper
until it is straight. Two paper alignment holes (Figure 2-8) are provided for this purpose. (A
straight line on the paper should just touch the bottom edge of each alignment hole. This is
where the bottom of each printed character will touch.) When ahgnmentis complete, move
the platen pressure release lever back, away from the platen.

Push the paper bail back. The rollers should ride on the paper.

2.6

Position the paper for the first line of printing. Push the right-hand platen knob in and
rotate (adjust) it if fine positioning is necessary.

PRINT DENSITY ADJUSTMENT

The hammer intensity control switch, shownin Figure 2-6, has three posmons high (H), medium (M),

and low (L). The desired setting will depend primarily on font size and the number of copies being

printed. As a rule, the switch is initially placed in the medium (center) position and moved, if necessary, after the test printout is made (Paragraph 2.7).

2.7 PRE-OPERATIONAL CHECKOUT
The purpose of the pre-operational checkoutis to ensure that the printer has been installed and loaded
properly andis ready for operation. Instructions for running the test program are containedin the
MAINDEC diagnostic listing (refer to Chapter 6). If the test must be stopped for any reason, such as
adjusting print intensity or adding paper, simply press the PAUSE switch on the printer control panel.
The PAUSE switch will light and cause the printer to finish all commands in process and then stop.
When service is completed, press the PAUSE pushbutton to resume testing.

NOTE
If the PAUSE mode lasts longer than 5 seconds, the
diagnostic will indicate a status error and will have to

~ be reinitiated.

2-10

CLAMP

7834-18

CLAMP

BUTTON

Clamp in Normally Closed Position

7834-19

Opening Clamp by Pressing Clamp Button

Figure 3-1

Forms Tractor Clamp Assembly
3-5

7834-34

Raise Forms Tractor Over Printer

7834-35

Lower Forms Tractor and Depress Clamp

Buttons to Engage Clamps to Shaft Below

7834-22A

Forms Tractor Properly Seated

Figure 3-2

Forms Tractor Installation

TAB

PLATEN PRESSURE RELEASE LEVER
(IN FORWARD POSITION)

Figure 3-3 Positioning of Platen Pressure Release Lever
When Forms Tractor Is Installed

7834-20

TRACTOR
UPPER RACK
ASSEMBLY

TRACTOR
CLAMP
SCREW

TRACTOR

TRACTOR
CLAMP
SCREW

TRACTOR

7834-22B

Major Elements of Forms Tractor
.

Figure 3-4

TRACTOR
LOWER RACK
ASSEMBLY

Figure 3-5 illustrates the procedure for loading fanfold paper through the slot in the desktop. Figure 3-

6 ilustrates the procedure for loading fanfold paper from the rear of the desk. The basic loading
procedure is essentially as follows:
1.

Make sure the platen pressure release lever is forward, as shown in Figure 3-3.

Pull the paper bail forward, away from the platen.

Insert the first of the continuous forms into the printer. If loading from the rear, move paper
over the tractor lower rack assembly and down behind the platen. Roll the paper around the
platen until it is approximately 15.24 to 20.32 cm (6 to 8 in) above the typing line. If loading
from the front, move the paper directly through the slot in the desk top, in front of the
platen.

Open the left-hand tractor assembly. Place the paper form over the teeth and then close the
tractor.

7834-38

Figure 3-5

Loading Paper Through Slot in Desk Top

7834-14

Figure 3-6

Loading Paper in Forms Tractor from Rear

Align the form, place it over the teeth on the right-hand tractor assembly, and close that
tractor. Some minor adjustment of the tractors may be necessary to ensure that the paper is
not too tight or too loose.
|

Tighten the tractor clamp screws.

Push the paper bail back into position against the paper form.

Use the platen knob to position the form for the first line of typing. (Normally, the first form
is used only to get the forms started through the forms tractor and is not used for printing.)
NOTE
The paper form should be aligned with the paper
alignment holes (Figure 2-8). If necessary, adjust the
feet on the forms tractor until alignment is correct.

- CAUTION
Tear paper only along perforations. Support paper
when tearing to avoid distorting the tractor-feed

holes in the paper in the machine.

3-10

3.4

CHANGING RIBBONS

Remove the old ribbon cartridge as follows:
1.

Remove the printer access cover (Figure 2-4).

Using both forefingers, push down on the two plastic latches (Figure 3-7A) that secure the

ribbon cartridge to the platform.

Using both thumbs, tilt the front of the ribbon cartridge upward so that the ribbon is clear
of the print wheel (Figure 3-7B).

Remove the ribbon cartridge and discard.

Install the new ribbon cartridge as follows:
1.

Turn the small ribbon advance knob (Figure 3-7B) in the direction indicated by the arrow,
enough to remove all slack from the ribbon.

Slide the exposed portion of the ribbon behind the two ribbon guide posts locatedin front of
the print wheel (Figure 3-7A). Then snap the cartridge into place on the platform.
Gently rock the ribbon cartrldge up and down several tlmes to make sure that the ribbonis
free of the print wheel.

If necessary, tighten the ribbon by means of the ribbon advance knob.

When completed, install the printer access cover.

3.5 CHANGING PRINT WHEELS
To remove the existing print wheel, proceed as follows:
N

First, remove the printer access cover and the ribbon cartridge (Figures 2-4 and 3-7).
2.

Tilt theinner carriage assembly away from the platen and hold stationary with one hand
(Figure 3-8).

With the other hand, remove the print wheel by pulling straight up on the knob at the print
wheel hub (Figure 3-9). Place the print wheel in its protective case.

3-11

PLATFORM

LATCH

PRINT WHEEL

RIBBON

PLATFORM

CARTRIDGE

LATCH

7834-36

Press Down on Platform Latches

RIBBON

PLATFORM

RIBBON

GUIDE POST

RIBBON

ADVANCE KNOB

7834-25

Tilt Ribbon Cartridge Upward
Figure 3-7

Ribbon Removal
3-12

SHAFT
EXTENDER

INNER CARRIAGE ASSEMBLY

RIBBON LATCH

ARM

PRINT WHEEL

7834-27

RIBBON

ALIGNMENT

Figure 3-8

Inner Carriage Assembly Titled Away from Platen

MOTOR SHAFT

TAB

LATCH

To install another print wheel, proceed as follows:
1.

Tilt the inner carriage assembly away from the platen to expose the print wheel motor shaft

Remove the print wheel from its protective plastic case and position the wheel over the print
wheel motor shaft (Figure 3-9), rotating the wheel until its alignment hole lines up with the

(Figure 3-8).

alignment tab protruding from the shaft hub.

Press thé hub of the wheel firmly onto the end of the print wheel motor shaft and lock the

wheel in place.

NOTE

Be sure the wheel is firmly seated or printing errors
will occur.

Move the inner carriage assembly back to its normal operating position.

When installation is completed, install the ribbon cartridge and then the printer access cover.
3-13

m—

ALIGNMENT

WHEEL

HOLE

7834-26

PRINT WHEEL

MOTOR SHAFT

Figure 3-9

View Showing Print Wheel Motor Shaft
and Print Wheel Alignment Hole

3-14

3.6

ENERGIZING THE PRINTER ASSEMBLY

The circuit breaker on the desk power control box controls power to the printer (Appendix D). When
the circuit breakeris closed, its associated lamp will light, and ac power will be applied to the printer
power supply. DC power will then be applied to the printer itself. When the printer is ready for
operation, the PRINTER READY indicator on the operator control panel (Figure 1-2) should light.
The printer is now ready to receive and print data received from the user system.
WARNING
The printer is electronically controlled. It has few
moving parts and, therefore, provides trouble-free
operation for long periods of time. The operator can
help extend these trouble-free periods by exercising
reasonable care in the handling of food and beverages
around the printer. Should an accidental spill occur,
maintenance personnel should be called as soon as
possible to clean and check the unit thoroughly. For
operator safety, danglmg jewelry should not be worn
since it could get caughtin the printer carriage. Also,
never make or break cable connections to the printer
while power is on. Finally, remember that applying
power to the printer initiates a Restore sequence,
which includes movement of the carriage. Make sure
the carriage is free to move before applying power.
3.7

NORMAL OPERATING PROCEDURE

Normally, the operator performs no maintenance on the printer except to load paper change print
wheels, and install ribbons. When the printer is energized, and operating on-line proceed as follows to
stop the machine for servicing exhaustible supplies:

Press the PAUSE pushbutton The PAUSE pushbutton should light. A short time later, the

printing operation should stop.

Remove the printer access cover and perform the desired operation.

Install the printer access cover.

Press the PAUSE pushbutton The PAUSE pushbutton indicator should go out. A short

time later, the printer operation should continue.

If a mylar ribbon cartridgeis installed, a sensor at the end of the ribbon will activate an electrical signal
to stop the printer. When the printer stops, the PRINTER READY indicator will extinguish and the
END OF RIBBON indicator will light. Proceed as follows:

Press the PAUSE pushbutton.

2.
3.

Replace the ribbon cartridge.
Press the PAUSE pushbutton.

When the printing operation continues, the PRINTER READY lamp will again light and the END |
OF RIBBON indicator will go out.

‘To prevent the printer from running out of paper during normal operation, add a sufficient supply
before starting the operatlon Allow approximately 2.54 cm (1 in) of fanfold paper for 2.5 hours of
printing.

3-15

3.8 OPERATOR MAINTENANCE
Table 3-2 summarizes maintenance procedures that should be performed by the operator at scheduled
intervals. These procedures are primarily limited
to visual inspection and minor cleaning duties. Lubrication and major maintenance should be performed by qualified technical personnel only.

Table 3-2

Interval

Weekly or as
required

Operator Maintenance Chart

Action to be Performed
Use isopropyl alcohol saturated cleaning pads and wipers* to remove fingerprints and other smudges from the printer frame and cover.

Monthly or as

With power removed, clean the inside of the carriage area. If necessary,

required

remove and clean the forms tractor, paper guide cradle, and/or platen at that
time. (See Paragraphs 3.9, 3.10, and 3.11 for instructions on removing the
forms tractor, the platen, and the paper guide cradle, respectively.)

Clean the platen pressure rollers and paper bail tires using a platen cleaner
such as Fedron Platen Cleaner. Do not use alcohol on these or other rubber
parts.

The print wheel does not require cleaning under normal operating conditions. Slight ink build-up is normal, especially with a new cloth ribbon. Only
unusually severe and prolonged operating conditions will make print wheel
cleaning necessary, in which case isopropyl alcohol can be used.
*91% isopropyl alcohol.

3.9 FORMS TRACTOR REMOVAL
To remove the forms tractor, proceed as follows (Figure 3- 2)

Make sure the paper bail is pulled forward.

Press the two clamp buttons down as far as possible and lift the forms tractor straight up.
Exert sufficient strength to lift the assembly clear of the printer in one upward motion.

Instructions for re-installing the forms tractor are contained in Paragraph 3.3.2.
3.10

SKIRT AND PLATEN REMOVAL

In order to remove the friction-feed platen, it is first necessary to remove each skirt (Flgure 3- 10) as

Remove the access cover.

Swing the back end of the skirt inward, toward the carriage assembly.

Push the front end of the skirt into the skirt holding bracket.

Lift up the back end of the skirt and remove
the skirt completely from printer frame.

3-16

-T

Sha

follows:

SKIRT

7834-1

HOLDING
BRACKET

Figure 3-10

Skirt Removal

With the skirts removed, proceed as follows to remove the platen:
1.
2.

3.
3.11

Move the paper bail forward.
‘Press both platen latches as shown in Figure 3-11.
Raise the platen upward, straight out of the printer.

PAPER GUIDE CRADLE REMOVAL/INSTALLATION

With the skirts and platen removed (Paragraph 3.10), the paper guide cradle can be lifted directly out
of the carriage area (Figure 3-12). To re-install the cradle, place it over the rollers so that the rollers

- protrude through the slots in the cradle.

PLATEN

LATCH

PLATEN
LATCH

(RIGHT)

Figure 3-11

Pressing Platen Latches

3-18

7834 7

PAPER

GUIDE
CRADLE

PAPER
BAIL

CARRIAGE
SUPPORT

'CARRIAGE

ASSEMBLY

7834-33

SHAFTS

Figure 3-12

3.12

View Showing Paper Guide Cradle

PLATEN AND SKIRT INSTALLATION

With the skirts removed (Figure 3-10), proceed as follows to install the friction-feed platen:
1.

Make sure the paper bail is pulled forward and the paper centering scale is moved up and
out of the way.

Pick up the platen by both knobs, holding the end with the grooved collar in the right hand

(Figure 3-13).

Position the platen over the printer so that the collar on the right end is aligned with the
right-hand printer side frame. Press the platen latches with both thumbs (Figure 3-11) and
install the platen so that the gears mesh. Release the platen latches.
Rotate the platen to be certain it is seated properly (Figure 3-14).

GROOVED COLLAR

PLATEN

7834-6

Figure 3-13

Readying Platen for Installation

3-20

7834-1

Platen Installed

Figure 3-14

To install a skirt, proceed as follows:
1.

Make sure the access cover is removed.

Hold the skirt directly over the end of the cover frame near the platen knob (Figure 3-10).

Tilt the front end of the skirt slightly downward and insert it fully into the skirt holding
bracket.

Move the back end of the skirt downward and toward the outside frame until the skirt snaps
in place.

Install the access cover.

3.13

EMERGENCY OPERATION

Pressing the PAUSE pushbutton is considered the normal procedure for stopping a printing operation.
If this action fails, remove ac power to the printer by opening the associated circuit breaker (Appendix
D).

3.14

DE-ENERGIZING THE PRINTER ASSEMBLY

For normal removal of power from the printer system, open the associated circuit breaker. Do not
open the circuit breaker or remove primary ac power while the machine is printing. Wait at least 5
seconds after the last message is printed.

3-21

CHAPTER 4

PROGRAMMING

4.1

GENERAL

4.2

CONTROLLER INTERFACE SIGNALS

This chapter contains detailed information for programming LQPS8 Printer Systems. In addition to a
tabulation of specific address assignments and bit definitions, two sample programs are included.
These programs illustrate the different functions that can be programmed in a typical word-processing
application. The logic and timing involved in the execution of the instructions are covered in Chapter

Figure 4-1 identifies the various interface signals between the Omnibus, the LQP8-E controller, and
the LQPO! printer. The manner and sequence in which these signals are asserted determine the differ-

ent modes of printer operation.

In a typical word processing application, where continuous text is to be printed, the programming
sequence is generally as follows:

The system is initialized, returning the printer carriage to the leftmost position.

The printer statfis lines are sampled.

The single-colored ribbon is lifted.

The first data character is strobed into the printer and printed.

The carriage is moved to the next position.

The second character is printed, and so forth.

At theend of the line, the paper is moved upward (or backward) as in a regular line feed.

The carriage either remains at the right end to print the next line from right to left, or 1s
programmed to return to the leftmost position so that printing again occurs from left to
right.

Any number of variations to the aforementioned sequence are possible, depending on the way in which
the Input/Output Transfer (IOT) instructions are programmed.

Omnibus interface signals are described in the appropriate PDP-8 manual. Printer interface signals are
covered in detail in Chapter 5 of this manual. Bit configurations at the output of the controller status
register (LQPSR) are illustrated in Figure 4-2 and described in Table 4-1. Data transfer from controller
to accumulator (AC) occurs during execution of an IOT 6505 instruction. The controller data buffer
(LQPDB) merely stores a 12-bit data word and can be interrogated by an IOT 6501 instruction, if
required.

4-1

PRINTER READY L
' CHARACTER READY L
CARRIAGE READY L

r———
|
STATUS 7|
REGISTER

PAPER

LQPSR

_____ J
PDP-8

RIGHT
RIGHT
READY
L

CHECK
L

]

DATA (@:11) L

D(1024:1/2)
L
LQP8-E

TP@3 H

INTERFACE
CONTROLLER

o | BUS INIT H

RESTORE L

—

VIDEO

TERMINAL

MD(@3:11)L

1/0 PAUSE L

|_INTERNAL I/0 L

Mo
MORY
ME

(FLOPPY DISK)

CHARACTER STROBE L

LQP
@1

CARRIAGE STROBE
L

PRINTER
(NOTE 1)

(NOTE 2)| pRINTER SELECT L
o

RIGHT PAPER STROBE L

E oama _}

INT RQST L

BUFFER

SKIP L

Lap(pg)

:
[

coL

DATA

CiL

BUFFER

LIFT BLK
LK L

I|
i

LQP(DB)

L—

r—— =71
|

DONE

FLAG

NOTES:

Only those printer signals actually connected

The

PRINTER SELECT line is grounded and

are shown on this diagram.
therefore is always asserted.
08-1720

Figure 4-1

Controller Interface Signals

MSB

LSB

PRINTER

CARRIAGE

READY

CHARACTER
READY

CHECK

PAPER
READY

LEFT
PAPER(1)

BAIL

LIFT

DISENGAGE (1)

BLK(1)

PAPER
ouT

LIFT
RED (1)

INTERRUPT
ENABLE
(1)
08-1721

Figure 4-2

LQPSR Bit Interpretation

4-2

Table 4-1

Data
Bit

Bit Description for LQPSR

Name

Description

PRINTER
READY

When set, this bit indicates that the printer is properly supplied with power and no internal malfunc-

tions exist. During restore, this bit is cleared. This

is a read-only bit.

CHARACTER
READY

When set, this bit indicates that the printer is ready
to accept a print command. This is a read-only bit.

CARRIAGE
READY

When set, this bit indicates that the printer is ready
to accept a carriage motion command. This is a

PAPER
READY

When set, this bit indicates that the printer is ready
to accept a paper motion command. This is a read-

read-only bit.

only bit.

UNUSED

LEFT

When cleared, this bit enables the RIGHT PAPER

CHECK

When set, this bit indicates that an internal mal-

PAPER OUT

Not used.

BAIL

Not used.

LIFT

Not used.

LIFT
BLK (1)

When set, this bit indicates that single-color ribbon
has been raised into position for printing. When

PAPER (1)

STROBE.

function exists within the printer mechanism, or
the power supply has gone out of tolerance, and
will clear all the printer READY status lines
(LQPRSR bits 0, 1, 2, and 3). If this condition was
caused by improper programming or by a transient
error condition, this bit must be cleared by IOT or
system reset before the printer will execute any further commands. This is a read-only bit. If a permanent error exists, this bit cannot be cleared and
corrective maintenance must be performed.

DISENGAGE

RED (1)

not set, it indicates that the ribbon has been
lowered.

INTERRUPT

ENABLE

When set, this bit enables an interrupt request to

the PDP-8 processor upon setting of the internal
controller DONE flag.

4-3

4.3

10T INSTRUCTIONS
|
LQPO1 operation is controlled by eight different IOT instructions. The format of a typical IOT instruction is shown in Figure 4-3. Bits 0-2 contain the op code, which must be octal 6 to specify an IOT
instruction on the PDP-8. Bits 3-8 contain the device selection code that is transmitted to every peripheral device whenever the IOT instruction is executed. The LQPS8 Printer System can be configured
to recognize codes in the range of 00s-77s. The standard configuration has a device code of 505. The
last three bits of the IOT instruction (bits 9-11) contain the operation specification code. These bits are
used to specify the eight different printer operations:

Standard IOT

Function

Mnemonic

6500

Skip on DONE flag

LQSK

6501

Read controller data buffer
(LQPDB) into AC

LQRB

6502

Move paper and clear DONE flag

LQMP

6503

Move carriage and clear DONE flag

LQMC

6504

Print character and clear DONE flag

LQPC

6505

Read controller status (LQPSR)
into AC and clear DONE flag

LQRS

6506

Write status (LQPSR) from AC
and set DONE flag

LQLS

6507

Restore printer and clear DONE flag

LQRE

[ 1

0 ]

DEVICE SELECTION

]
OPERATION

SPECIFICATION

08-1009

Figure 4-3

1OT Instruction Format

/«rSN

A detailed description of each IOT instruction is presented in Table 4-2.

4-4

Table 4-2
10T

Functional Description of IOT Instructions

Instruction

Functional Description

6500

Skip on DONE Flag

Enables program to skip the next instruction if the internal controller DONE
flag is set. This flag may be set in a number of ways as described by the
following 10Ts.

6501

Read Data Buffer (LQPDB) into AC

First clears the PDP-8 AC, then transfers the current contents of the con-

troller data buffer (LQPDB) to the AC.

6502

Move Paper and Clear DONE Flag

Causes the platen to move the paper a selected distance and direction in
increments of 1.22 cm (1/48 in). To produce paper motion, the AC is first
loaded with a binary word in bit positions 1-10, indicating a relative displacement of paper in multiples of 1.22 cm (1/48 in) (Figure 4-4). Bit 10 1s the
least significant bit and bit 11 is unused. Bit 0 indicates the direction of movement. Setting bit 0 = 1 reverses paper motion; setting bit 0 = 0 advances the
paper.

When the IOT is issued, the contents of the AC are transferred to the data
buffer (LQPDB), the AC is cleared, the controller DONE flag is cleared, and
the printer is given the paper motion command. The printer will immediately
negate its PAPER READY line [bit 3 of status register (LQPSR)] and ignore
any further paper motion commands. Upon completion of the paper movement, the PAPER READY bit will be asserted and set the internal DONE
flag.

NOTE

The user system must keep track of paper
positioning.

6503

Move Carriage and Clear DONE Flag

Causes the carriage to move a selected distance and direction in increments
of 0.3048 cm (1/120 in). To produce carriage motion, the AC is first loaded
with a binary word in bits 1-11, indicating the relative displacement of carriage motion in multiples of 0.3048 cm (1/120 in) (Figure 4-5). Bit 11 is the
least significant bit. Bit 0 indicates the direction of carriage motion. Setting
bit 0 = 1 moves the carriage to the left; setting bit 0 = 0 moves the carriage to
the right.

4-5

Table 4-2

Functional Description of IOT Instructions (Cont)

10T
Instruction

Functional Description

When this IOT is issued, the contents of the AC are transferred to the data
buffer (LQPDB), the AC is cleared, the DONE flag is cleared, and the printer is given the carriage motion command. The printer will immediately
negate its CARRIAGE READY line [bit 2 of status register (LQPSR)] and
ignore any further carriage motion commands. Upon completion of carriage
movement, the CARRIAGE READY bit will be asserted and set the internal
DONE flag.
NOTE
The user system must continually update
itself as to carriage position for proper
control of carriage motion, particularly
for carriage return. Otherwise, the carriage may crash into the left/right stops
and a CHECK error will be granted.
6504

Print Character and Clear DONE Flag

Causes a selected character to be printed. To print a character, the AC is first
loaded with the binary code for one of 96 available characters in a modified
ASCII format in bit positions 4-10 (Figure 4-6). Bit 10 is the least significant
bit. Bits 0, 1, 2, 3, and 11 are unused. When the IOT is issued, the contents of
the AC are transferred to the data buffer (LQPDB), the AC is cleared, the
DONE flag is cleared, and the printer is given the print character command.
The printer will immediately negate its CHARACTER READY line [bit 1 of
status register (LQPSR)] and ignore any further print character commands.
Upon completion of the printing operation, the CHARACTER READY bit
will be asserted and set the internal DONE flag.
6505

Read Status (LQPSR) into AC and Clear DONE Flag

Transfers the contents of the status register (LQPSR) into the AC and then
clears the internal DONE flag.
6506

Write Status (LQPSR) from AC and Set DONE Flag

Transfers current contents of AC into the controller status register (LQPSR)
and clears AC. Of 12 data bits, only 5 are stored in the printer buffer
(LQPPB) and also transferred to the status register (LQPSR); these are data
bits 5, 8, 9, 10, and 11. At the same time, the DONE flag is set. Any printer
operations that take place depend on the status of the data lines. If data bit
10 1s asserted, the LIFT BLK (1) status line (bit 10 of LQPSR) is asserted and
the printer ribbon is lifted to the up position. If data bit 11 is asserted, then
the INT ENBL (1) flag (bit 11 of LQPSR) is asserted. When the INT ENBL
(1) and DONE flags are both set at the same time, then the Omnibus signal
labeled INT RQST (Interrupt Request) is asserted. The ribbon will remain in
the up position and/or the INT ENBL (1) flag will be set until: (1) the controller is initialized; or (2) another IOT 6506 instruction is programmed with
a different data word. In this case, the Omnibus interrupt request will not
change.
|

4-6

Table 4-2

Functional Description of IOT Instructions (Cont)

ICT

Instruction

Functional Description

6507

Restore Printer and Clear DONE Flag

Clears a transient error condition within the printer (bit 6 of LQPSR) and
moves the carriage to the leftmost position. Upon receipt of the Restore
command, the DONE flag is cleared and the printer negates all of its
READY status lines (bits 0, 1, 2, 3 of LQPSR) while the carriage is positioning to its home position. Because of the slow speed of the carriage movement
during a restore, this IOT should not be used as a carriage return. The contents of the AC are both unaltered and unused by the restore IOT. Upon
completion of the Restore operation, the printer asserts all its READY lines
and the internal DONE flag is set.

The Restore operation also occurs whenever a system INITialize pulse is sent

by the processor. This feature can be deleted, if desired, by removal of jumper W7 on the M8366 controller module.
NOTE
If restore is used to clear a CHECK condition (bit 6 of LQPSR), the internal
DONE flag will not be cleared and should
be cleared by a Read Status instruction
(I0T 6505). If CHECK is not present or if
the restore is caused by a system INIT,
DONE will be cleared.

Example: Programming Paper Motion
An example for paper motion is shown below. To move the platen upward 1.27 cm (1/2 in), first find
the total number of increments required:
X

1.27 ¢cm (0.5 in) (48 increments/ inch)
24 increments (base 10)

Convert the number of increments from decimal to octal code, then code bit 0 for direction, thusly:

DATA

TO CONTROLLER
DATA OUT
TO PRINTER

1024 |

512

2
256 |

LINES (O:11)

128

172

PAPER MOTION

COMMAND

NOT

RELATIVE PAPER MOTION

USED

Az —

LDIRECTION OF PAPER MOTION:

IF FALSE (HI=+5V), PAPER ADVANCES

IFF TRUE (LO=GND), PAPER

REVERSES

< -

1024 |

512

256

128

1/2

—J .

UPWARD
MOVEMENT

24,5=30g
08-1717

Figure 4-4

Programming Paper Motion

4-8

Example: Programming Carriage Motion
An example for carriage motion is shown below.
To move the carriage 15.24 cm (6 in) to the right, first find the total number of increments required:

15.24 cm (6 in) (120 increments /inch)
720 increments (base 10)

Convert the number of increments from decimal to octal code, then code bit 0 for direction, thusly:

DATA

DATA IN

TO CONTROLLER

—
0

DATA OUT
70 PRINTER | 1024

~N/
1

512

256 |

LINES (0:11)

- ———

128 |

~—————————

A——

1/2

CARRIAGE MOTION

COMMAND

- RELATIVE CARRIAGE MOTION

&s 120

\—DIRECTION OF CARRIAGE MOTION

IF FALSE (HI=+5V), CARRIAGE MOVES TO

IF TRUE (LO=GND), CARRIAGE

1024 | 512 | 256 | 128 | 64

R/_/g

172

RIGHT

MOVEMENT

RIGHT

MOVES TO LEFT

720,0=13204

08-1716

Figure 4-5

Programming Carriage Motion

4-9

Example: Programming Printer Commands

An example for printing a character is shown below.

To print the uppercase letter A, first find the modified ASCII code in Appendix A. In this case, the
code is 0202g, and is programmed as follows:

DATA

—
DATA IN
)
TO CONTROLLER
DATA OUT

1024

TO PRINTER

—
1

512

256

LINES (O:11)

—
4

128

6
16

—

N ————— T
1
10
9
2

172

NOT

PRINTER

NOT USED

eUSED>

ONE OF 96 CHARACTERS

COMMAND

IN A MODIFIED ASCII FORMAT

1§

1024

512

256

128

1/2

02028
08-1718

Figure 4-6

4.4

Programming Printer Commands

PROGRAMMING CONSIDERATIONS

The following conditions should be considered when programming the printer system:

Overlap - System throughput can be improved greatly by overlapping commands to the printer.
The printing, carriage motion, and paper motion hardware are each independently selected and
controlled to allow more than one operation to be in process at any given time. Only the actual
firing of the print hammer is interlocked with carriage and paper motion. This allows the user to
give a paper motion command, carriage motion command, and print character command in rapid
succession. This will start the carriage, platen, and print wheel into simultaneous motion. If the
print wheel positions properly prior to completion of carriage and platen motion, the print hammer will wait until all motion stops before firing. Care should be taken when interpreting interrupts. In this case, an interrupt can only indicate that the printer status has changed since the last
examination of the LQPSR and any subsequent commands must be based on the change in
status. Printer operations will actually occur in the same order that they are given.

Ribbon Lift — The print hammer is interlocked with ribbon motion to inhibit the execution of
either of these functions while the other is in progress. This allows the acceptance of a ribbon lift
followed immediately by a print character or a print character followed immediately by a ribbon
drop without fear of misprinting a character.

4-10

DONE Flag - In addition to those conditions already defined in Table 4-2, the following conditions will set the internal DONE flag:

PAPER OUT (bit 7 of LQPSR) being asserted.

PRINTER READY (bit 0 of LQPSR) being negated.
CHECK (bit 6 of LQPSR) being asserted.

Ribbon Out — The printer is equipped with a ribbon out detector to prevent the deterioration of
print quality on an unattended machine. If a mylar ribbon (with an end-of-ribbon sensor) is
exhausted, the CHARACTER READY bit (bit 1 of LQPSR) will be negated and the printer will
not accept any print character commands until the ribbon is replaced.

4.5

PROGRAMMING EXAMPLES

Figures 4-7 and 4-8 illustrate the programming involved when an LQP8 Printer System is used in

conjunction with a DIGITAL DS310-W Word Processing System.

56
57
58
59
60

PAL1®

V142A

2236
9237
eaug
paut
pau2

1270
6583
127@
1272
3272

p243

5217

8264

7313

@247

6585

64
65
67

gaus
@2ub
62se

€251

1272
4503

3257

SPACE

/GET CARRIAGE MOVE ENT MAGNITUDE
/1SSUE MOVE CARRIAE IOT
/GET CARRIAGE MOVE 1ENT MAGNITUDE
/ADD CURRENT CARRKI\GE POSITION
/UPDATE CARRIAGE PISITION POINTER

SPACE
SAVPOS
SAVPOS
PRNTLP

/CONTINUE PRINTING CURRENT LINE

CLA CLL IAC RTR /SET BIT ZERO FOR :.EFT MOVEMENT

CRLF,

TAD
LEMC

LARS
AND

TAD

SAVPOS
K4ao

K742@

/ADD CARRIAGE POSI "ION
/MOVE. CARRIAGE TO - OLUMN @
JREAD STATUS REGIS 'ER
JMASK BIT ONE

/ADD COMPLEMENT OF PAPER READY

6502

LGMP

/1SSUE MOVE PAPER .OT

1265

TAD

2255

PAGE 1=1

/SKIP 1F PAPER READLY =
/WALT FOR PAPER RE..DY

2256

10155

SZA CLA
o=l
JHP

7640
5247

JMP

1274

@252
2253

2254

TAD
LGMC
TAD
T4D
DCA

2275

69
70

4=MAR=Té

TAD

1271}

LINE

/GET PAPFR FEED MAGNITUDE

CL4 CLL IAC RAL /SET BIT 10

7335

DCA
DCA

3255
3272

CHAR

CHAR
SAVPOS

/ADD CHARACTER €ODt

JUPDATE TO NEXT CH,RACTER
/CLEAR CARRIAGE FOi ITION POINTER

75
76

2260
8261

2263

S2i4

g265

2000

CHAR,

/STORAGE AREA OF CHARACTER TO PRINT

¢27¢

[o14

SPACE,

Daid

JCHARACTER SPACING MAGNITUDE

2204

LENGTH, 2204

82
83

85
86

e262

Q264

A26h
A2e7

2271
3272

2273
@274

89
92
91
92

2275
2276
@277
gige

@3g1

94
95
96
97
98

8382
2383

152

2267

JNP

JMP

5200

3020
B2o@

@goze
2000

Q40D
212D
2020
eoee

Ki@d,
King,
KEaoa,
K62gP,

@400
7100
2003
6200

7088
Toud

K70¢%,
Miu@,

Kigee,

/INCREMENT LINE COLNT

JCONTINUE : ITH NEXT LINE

/START OVER

/CHARACTER COUNTER
JLINE COUNTER

/LINE SPACING MAGNITUDE
/CARRIAGE POSITION POINTER

7420

1220

BEGIN

CHRCNT, ©
LINCNT, @

K7402,

TLBO

LINCNT

PRNTLP=3

OF CHARACTERS PER LINE
/NUMBER

1390
7008
7640

/
/

$$5

Figure 4-7

Programming Example No. 1 (Sheet 1 of 2)

4-11

Vidaa

NN e

PALLD

Pt
Pt
Qe

e
.

SN
T

I
U

EXAMPLE

6522
6521

SINCE
OTHER

(OMMANDS
FEADY BITS,

6522

6523
6524
6525
6586
65¢7

/SKIP ON DONE FLAG
/READ DATA BUFFER
/MOVE PAPER
/MOVE CARRIAGE
/PRINT CHARACTER
/REAG STATUS REGISTER
/LOAD STATUS REGISTER
/RESTORE PRINTER

LORE=6587
J

£22¢

/
X200

eevd

£527

dedl

BeGIN,

6525

8ree

g274

B223

1275
7642

LARE

/RESTCORE PRINTER
/JREAD STATUS REGISTER

LGRS
AND

" TAD

K7402

/MASK

K4go

/ADD COMPLEMENT

READY

BITS

2224
2233

5221

BEGIN+1

/SKIP
/WAIT

g2¢o

1276

TAD

KiRy

3265
7T3I2%
0546

DCA

/GET

FIRST

ASCII

CHAR
IAC RAL

/StVE

FOR

PRINTING

TAD

M149

DCA

@ei4

T40

173

LINCNT
LENGTH

0215

Tods

CIA

¢3

CLa

CLA

¢21e

3266

DCa

i vy se

w2dd

SZA
JMP

1343
1267

eel7

6c05

ge77

MAXIMUM THROUGHPUT
INDEPENDENT OF ALL

/
LASK=6502
LGRE=6C01
LOGMP=ESR2
LAMC=65¢3
LArPC=6504
LGRS=05025
LGl S=6526

2212
22118
2212
cdl}

b ~4 O

LINE (132 COLUMNS) OF EACH OF THE
USING THE STATUS REGISTER READY BITS
THE PRINTER IS READY TO ACCEPT 4 COMMAND,

/T0 INDICATE WHEN
/THIS METHOD RESULTS IN
/ARE OVERLAPPED AND ARE

£~ o

[ 20 S

(VR WM NN IAVIE AT o na
AV
noLss ad I\J o=
SO
M~ 0N
F&N

PROGRAMMING

/THIS PROGRAM PRINTS ONE
/96 PRINTABLE CHARACTERS

N L WS

poon

e 80 DD~

/
/

N W W W

/LGP=8
/

PAGE

19155

4=MAR=T76

CLL

LGLS

PRNTLF,

/SET
/LIFT

CHRCNT

L3RS

CODE

172

BIT

RIBBON

/GET
/SET

NUMBER OF LINES
UP LINE COUNTER

/GET

NUMBER

/SET

CHARACTER

MASK

STATUS
BLT

CHARACTERS

/NEGATE
/READ
RSAa32

AND

ALL RE..DY

IF RESTORE COMPLETE
FOR RESTORE COMPLET::

PER

LINE

COUNTER

ONE

1329

TAD

@2z
£2e3

To49
5el’7

SZA
JMP

/WALIT

¢ezé

12865

o=y

TAD

CHAR

/GET

2225

€524

LGPC

@2cee

6585

LGRS

23py

AND

K122

/MASK

S8
53

2239

Todg

TAD
SZ4

Kij0o

@23

1322

9232

5226

JMP

€233

2cobb
741
5244

187

/ADD COMPLEMENT OF CARRIAGE READY
/SKIP IF CARRIAGE READY = 1
/RAIT FOR CARRIAGE READY
/INCREMENT CHARACTER COUNT
/SKIP IF NOT END OF LINE
ZEND OF LINE

¢z2l

52
53
54
55

e234

@235

Figure 4-7

Kopae

CLA

/SKIP

COMPLEMENT
1IF
FOR

CLA

=6
CHRCNT
CRLF

CHARACTER
READY

CHARACTER

BIT

CHARACTER

/ISSUE PRINT
/READ STATUS

SKP

JMP

/ADD

READY

CHaARACTER
REGISTER

10T

Programming Example No. 1 (Sheet 2 of 2)

PALLD

Vidca

/LGP=8 PROGRAMMING EXAMPLE

R O® N0 U

W WA G WY e W W (2] IAVINAVIN
U L VI ANVN
TVY Y Pt fts Oh Gt ot Pl ot P DD~
S E NN - o3] OO~ W £ Wive—9 DDLU
£ NV -

/OVERLAPPED,

/ENSURE THAT
/WILL RESULT

6502

6591
6502
6533

6584
6565

6586

6527

2200

02¢e

6547

2221

6525

¢c2e

2310
1311
764¢
e

A223
2224
@225

Qceb
¢ea7
G2y
a2t

1327

0224
@2eas

7640
5272

g2esb
eezav

653¢C

223¢

e3al
7412

N
o

/RESTORE

LGRS

TAD

CLA

READY

IN EACH CASE,

ANY

ERROR

REGISTIR

BITS

/ADD COMPLEMENT

BEGIN#1
K10

/GET

FIRST

/GET

LINE

CHAR
IAC RAL

LENGTH

/SKIP
/WAIT

LENGTH,

CHAR

JPRINT CHARACTER
/GET CODE SENT

CHRCNT

OF CHARACTERS

UP CHARACTER COUNTER
CHARACTER TO FRINT

La®C
TAD

ERROR

NUMBER

/SET
/GET

JMP
LESK
JMP
12
SKP

LL READY

CHARACTER CODE

/SAVE FOR PRINTING
/SET BIT 10
/LIFT RIBBON

CHRCNT
CHAR

SAVBUF

IF ALL READY
FOR READY BIT;

/NEGATE

TAD
SAVBUF
SZA CLA

Figure 4-8

/MASK

DC 4
TAD

CIA
DCA
LGRB

5226

IS MADE AFTER EACH COMMAND TOQ

PRINTER

STATUS

K4go

CIA

PRNTLP,

/READ

K7408

DCA
CLA CLL
LELS

3397
65014

2223

LORE

TAD

3304

LOADED

SZA
JMP

1306

Tadl

fo=

RESULTS

/MOVE PAPER
/MOVE CARRIAGE
/PRINT CHARACTER
/READ STATUS REGISTE?
/LOAD STATUS REGISTER
/RESTORE PRINTER

AND

6536

g22¢
e221
2222

2231

/
%200
/
/
BEGIN,

7385

1300

Lr L) Py o=
)

OiF EACH OF THE

/SKIP ON DONE FLAG
JREAD DATA BUFFER

LASK=6500
LQRB=6501
LOMP=6502
LAMC=6503
LGPC=65a4
LGRS=6545
LGLS=6586
LQRE=6507

1312
3322

6534

A CHECK OF THE DATA BUFFER

PRl

@216

(132 COLUMNS)

THE CORRECT DATA WAS
IN A PROGRAM HALT,

/
/

ac17

gl SR

ONE LINE

/IN & SLOWER PRINTING SPEED SINCE THE PRINTER COMMANDS ARE NOT

< WL

/THIS PROGRAM PRINTS

000

/96 PRINTABLE CHARACTERS USING THE DONE FLAG "0 INDICATE
/WHEN THE CURRENT PRINTER OPERATION IS COMPLEE, THIS METHOD

1388

LNV ) S i

/
/

2215

IR AR

PAGE

7241

WM& WiV

12:57

R
213
¢d1d

[SAIRV AR

U=MAR=T76

/JNEGATE FOR CHECKI!NG DATA BUFFER
/SAVE FOR CHECKING DATA BUFFER
/READ DATA BUFFER

/ADD DATA CHECK VA .UE
/SKIP IF DATA SENT = DATA READ

/GO TO ERROR ROUTINE
/TEST DONE FLAG
/WAIT FOR DONE FLAG
/INCREMENT CHARACTER COUNT
/SKIP IF NOT END CF LINE

Programming Example No. 2 (Sheet 1 of 2)

4-13

PALLD

Vid2a

d=MAR=T6

@232

4252

JMP

2234

6523

LAMC

gedd
g2dy

6521
1327

goud
@2u5

65¢0
5244

2251

5215

@252

7313

22335
g235
0236
8237
@242
g243y

geus
2247
225@

1383

TAD

1323
7041
3337

12:57

PAGE

1=1

CRLF

/END

OF LINE

SPACE

TAD
CIA
DCA

SPACE

SAVBUF

LARB
TAD

SAVSUF

/SET

TAD
TAD
DCA

@253
2254

1395
65093

@256
2257
g2ed

CRLF,

SPACE
SAVPOS
SAVPOS

CLA CLL

TAD
LGMC

SAVPOS

5255
1324
6%02

JMP
TAD
LaMP

=1
LINE

@as2

S26!

JHMP

g2ed
Be6s
gebsd
¢267
#2735
@274

t1ige
3328
3305
2332
S212
5S2d¢e

TAD
DCA
DCA
152
JMP
JMP

2255

2261

Q253

650@

LOSK

4570

CLA

CLL

ZERD

DONE

FLAG

/WAIT FOR DOGNE FLAG
/GET PAPER FEED MAGNITUDL
JADVANCE PAPER TO NEXT L NE
/TEST

IAC

BIT

/ADD CURRENT CARRIAGE POCITICN
/MOVE CARRIAGE LEFYT TO CULUMN @
/TEST

L3sK

7325

/READ DATA BUFFER
/ADD DATA CHECK VALUE

IAC RTR

1323
1335
3395

JMP

CARRIAGE

/GET CHARACTER SPACING MAGNITUDRE
/NEGATE FOR DATA BUFFER (HECK
/SAVE FOR CHECKING DATA EUFFER

PRNTLP

SZA CLA
JMP
ERROR

/MOVE

/SKIP IF DATA SENT = DAT+ READ
/GO0 TO ERROR ROUTINE
JTEST DONE FLAG
/WAIR FOR DONE FLAG
/GET CHARACTER SPACING M/ GNITUDE
/ADD CURRENT CARRIAGE PQSITION
/SAVE NEW CARRIAGE POSIT.ON
/CONTINUE WITH CURRENT L.NE

764
S272

LRSK
JMP

/GET CHARACTER SPACING M/GNITUDE

RAL

OONE

FLAG

/wAIT FOR DONE FLAG
/SET

BIT

CHAR
/ADD CURRENT CHARACTER CUDE
CHAR
/SAVE NEW CHARACTER CODE
/CLEAR CARRAIGE POSITION POINTER
SAVPOS
/INCREMENT LINE COUNTER
LINCNT
PRNTLP=3
JCONTINUE WITH NIXT LINE
/START OVER
BEGIN

¢272
@273

6521
7.0

gz74

7322

2275
2276
2el17

2322
@iay

(232
2zep

CHAR,
CHRCNT,

@e22

SAYPOS,

Qgap
2214
2229

@iz2e

¢224d

/GET COMPLEMENT OF DATA 3ENT
/COMPLEMENT BACK TO ORIGINAL VALUE

4
©

JCHARACTER STORAGE AREA
/CHARACTER COUNTER

LINCNT,
SPACE,
LINE,

@
Q2014
020

LENGTH,

€204

¢3i{

Q24g2

KUR3,

2312

Qiee

Kiea,

giee

0313

Teg2

Té&d9

K743,

Mid3,

JHALT WITH DATA SENT

INM

/CARRIAGE PCSITION POINTZR

/LINE LENGTH COUNTER

/SAVE AREA FOR DATA BUFFZIR CHECK

7429

7642

PaLl1e

Videa

d«MAR®76

10157

PAGE

1=2

/
$38

Figure 4-8

/LINE COUNTER
/CHARACTER SPACING MAGNITUDE
JLINE SPACING MAGNITUDE

SAVBUF, @

e3ig

CLL

/READ DATA BUFFER
/JHALT WITH DATA BUFFER IN AC

TAD SAVBUF
CIA
HLT

B¢y

23537

LGRB
CHLT
CLA

11g7
To4d
7452

2332
@333
2324

2325

ERROR,

Programming Example No. 2 (Sheet 2 of 2)

4-14

Inputs to the printer include: 4 Strobe lines, 12 Data lines, a Printer Select line, a Top of Form line, a
Bail Disengage line, and Ribbon Lift and Restore command lines. (The Top of Form line, the Bail
Disengage line, the Lift Red line, and the Left Paper Strobe line are not used with the DEC
DATASYSTEM 310W.) Outputs from the printer include: 5 Ready lines, a Check line, and an unused
Paper Out line. All of these lines are channeled from printer connector J7 (located on top edge of the
Logic 1 PCB) to connector J1 on the M8366 controller board. Power is applied to the printer from the
printer power supply. Power is applied to the controller from the PDP-8 power bus.

The function of each printer interface signal is described in Table 5-2.
Table 5-2

Printer Interface Signals

Signal

Function

PRINTER
SELECT Line

When TRUE (low), this signal allows the printer to respond to other input
commands and enables the output status lines to the controller.

DATA Line

Twelve data lines receive binary coded information which represents various
operations for each printer command. These lines must be asserted at least
200 ns prior to any strobe command.

Printer Commands: Data lines 04 through 10 (Figure 5-1) represent one of 96
characters in a modified ASCII format. Data 04 is the most significant bit.
Data 1/2 and 128 through 1024 are unused.

Paper Motion Commands: Data lines 01 through 10 represent a relative paper
position motion in increments of 1.22 cm (1/48 in). Data 01 is the most
significant bit. Data 0024 indicates the direction of paper motion. If FALSE
(high), the paper advances. If TRUE (low), the paper reverses. Data 1/2 is
unused.

Carriage Motion Commands: Data lines 01 through 11 represent a relative
carriage motion in increments of 0.3048 cm (1/120 in). Data 01 is the most
significant bit. Data 0024 indicates the direction of carriage motion. If
FALSE (high), the carriage moves to the right. If TRUE (low), the carriage

moves to the left.
CHARACTER
STROBE Line

;

This strobe pulse starts the print wheel in motion to position the selected
character in front of the print hammer. When all print wheel, paper, and
carriage motion has stopped, the hammer fires to print the character. Minimum pulse width is 500 ns.

CARRIAGE
STROBE Line
-RIGHT PAPER

This strobe pulse moves the carriage assembly a selected direction and dis-

tance. Minimum pulse width is 500 ns.

In the LQPO1, this strobe pulse moves the entire platen a selected distance

STROBE Line

and direction. Minimum pulse width is 500 ns.

LEFT PAPER

(Available on special order only.)

STROBE Line

5-3

Table 5-2

Printer Interface Signals (Cont)

Signal

Funcfion

RESTORE

This strobe line causes the printer to abort all operations in process, clear any
error conditions, and move the carriage to the extreme leftmost position.

Line

LIFT BLACK
Line

Minimum pulse width is 500 ns.

This signal controls the print ribbon position. When LIFT BLACK is TRUE
(low), the ribbon is lifted to the up position for printing in the primary ribbon color. When LIFT BLACK is FALSE (high), the ribbon is dropped to
its down position for printing in the secondary color of a two-color ribbon or
to provide printed character visibility for a single-color ribbon. This signal is
interlocked with the character printing function. If either ribbon motion or
character printing is in process, the other will not occur until the first is
complete.

CHECK Line

This condition indicates that an error has occurred in the printer as a result
of a malfunction or an illegal command. All machine activity is stopped and
all input and output signals are disabled, except RESTORE. Only a
RESTORE strobe or the removal and reapplication of printer power can
clear a CHECK condition.

CHARACTER
READY Line

This line indicates that the printer is ready to begin a print cycle and will go
FALSE (high) while the printer is in the process of printing a character. This
line is suppressed when an END OF RIBBON condition occurs.

CARRIAGE
READY Line

This line indicates that the printer is ready to accept a carriage motion command. This line will go FALSE (high) while the carriage is in motion.

PAPER RIGHT
READY Line

This line indicates that the printer is ready to accept a paper motion com-

PAPER LEFT

This line is always FALSE (high). .

READY Line
PRINTER
READY Line

mand. This line will go FALSE (high) while the platen is in motion.

This line indicates that the printer is selected, is properly supplied with pow-

er, and no internal malfunction exists. The line goes FALSE during a
Restore operation.

PAPER OUT
Line

(In the LQPDI, this line is not used.)

5.2.4

Omnibus Interface Signals

5.2.5

PDP-8 Word Structure

Standard PDP-8 signals interface between the Omnibus and the controller. Detailed information on
the function and timing of these signals is contained in the associated PDP-8 maintenance manual.

The PDP-8 uses 12-bit words for both data and instructions. The function of the eight IOT instructions
is discussed in Chapter 4 of this manual; circuit operation during the execution of each instruction is
discussed in the following paragraphs.

5.4

5.3 DETAILED THEORY
5.3.1

Basic Printer Operation

When the circuit breaker on the printer desk is closed, dc power is applied to the printer via the printer
power supply. Initializing various circuits, clearing the controller DONE flag, restoring the carriage to
the leftmost position, and returning the print wheel to home position is usually accomplished by either
powering up the computer or (with the computer powered up) pressing the INIT key on the programmer’s console. Initialization can also be accomplished by executing a Clear All Flags instruction (IOT
6007) or a Restore instruction (IOT 6507). Thereafter, the sequence of operation in a typical word
processing application is generally, but not necessarily, in the following order:
1.

Reading the controller status register (IOT 6505) to sample the Ready lines.

Lifting the single-colored ribbon (IOT 6506).

Printing the first character (IOT 6504).

4.,

Moving the carriage to the next position (IOT 6503).

5. Printing the second character (I0T 6504).
6.

Moving the carriage to the next position (IOT 6503).

Repeating steps 2 through 6 until a complete line i.s printed.

Performing a line feed or other paper movement (IOT 6502).

Printing in the reverse direction (right to left) or performing a carriage return (IOT 6503)

and then printing in the forward direction (left to right).

Other operations include Skip on Done (IOT 6500) and Read Data Buffer (IOT 6501).
The theory of operation of each of the eight IOT instructions is discussed in the following paragraphs.
NOTE

The timing relationships in Figures 5-2 through 5-7
are approximate and not necessarily drawn to scale.

5.3.2

Restore Printer and Clear DONE Flag (I0T 6507)

Observe the controller block diagram in Figure 5-1 and the corresponding IOT 6507 waveforms in
Figure 5-2.

When the printer address is decoded, there is a match, and INTERNAL I/O L is asserted. At the same
time, the lines labeled D1 10T 7 L and D110T 2, 3,4, 7 H are asserted. When timing pulse TP3 occurs,
TPO3 H is asserted, so that D1 TP3 L is asserted. The leading edge of D1 TP3 triggers the 2 us oneshot. The high output of the 2 us one-shot clocks D1 IOT 7 L into the corresponding D flip-flop,
whose one output is applied to a NAND gate. The low output of the 2 us one-shot is labeled D3
CLEAR DONE L and is also asserted at this time, causing D5 DONE (1) H to be negated.

5-3

TPO3H

1/0 PAUSE L
MD (©3:08) MATCH

INTERNAL I/0 L

D1 IOT 2:7 L

DI TP3 L
D3 CLEAR DONE L
D5 DONE (1) H

TPO3H

[¢

{

]

TPO3H

[ml

|
Je——15xSEC —]
[

(¢

{ ¢

(

— L]

»|

le———— 2 usEC

(

)
‘

REE

‘]

RESTORE L

STROBE ONE SHOT

))

{

D4 DONE FLAG H

D5 CLK DONE H

1
B

]

LDEPENDS ON TIME REQUIRED
FOR PRINTER OPERATION

08-1817

Figure 5-2

Waveforms for IOT 6507 (Restore Function)

At the end of 2 us, the high output of the settling delay one-shot goes low, triggering the strobe oneshot. The high output of the 500 ns one-shot gates D1 IOT 7 L into the printer as RESTORE L. The
Restore strobe clears any printer error conditions and initiates movement of the carriage toward the
extreme leftmost position and movement of the print wheel toward its home position. While the carriage and print wheel are moving, the printer negates all of its Ready status lines. When the strobe oneshot times out, RESTORE L is negated. Upon completion of the Restore operation, all of the printer
Ready status lines are asserted. The end result is that D4 DONE FLAG H is asserted. This, in turn,
enables the first of two sequentially arranged flip-flopsin the sync logic (flip-flop E1-5). Setting of the
first flip-flop occurs on the trailing edge of the next D1 TP3 L clock pulse and causes the second flipflop (E1-9) to be enabled. Generation of the next D1 TP3 L clock signal now effects the following:
1.

Asserts signal D5 DONE (1) H which, in turn, generates the INT RQST L signal to the
PDP-8.

Asserts signal D5 CLR DONE H to clear the READY detect flip-flops and negate signal D4
DONE FLAG H.

Another way of restoring the printer is to assert BUS INIT H. In this case, D1 INIT L is asserted, so

that RESTORE L is asserted (provided jumper W7 is installed), DS DONE (1) H is negated, and all
registers and flip-flops are cleared. When D3 LEFT PAPER (1) H goes low, the PAPER RIGHT
READY L line to the status register is enabled. When BUS INIT H goes low, D1 INIT L goes high, so
that RESTORE L is negated. Signal D5 DONE (1) H is asserted to generate INT RQST L in the same
way as described in the preceding paragraph.
The CHECK L signal remains negated until an error or malfunction occurs, at which time it is
asserted. A Restore sequence will clear a CHECK condition but will not clear signal DS DONE (1) H
(DONE flag). In this case, the DONE flag should be cleared by a Read Status instruction (IOT 6505).
Removal and reapplication of printer power will also initiate the Restore sequence to clear a Check
condition, but not the DONE flag.

5-6

5.3.3

Read Status Register (I0T 6503)

Observe the controller block diagram in Figure 5-1 and the corresponding IOT 6505 waveforms in
Figure 5-3.

TP3 H

—>|_|<—90—110 ns
I1/0 PAUSE L

MD (03:08) MATCH

INTERNAL I/0L

D1 IOT 5 LI

CoL

.‘

oT
|

CiL

DATA (O:11)
L

DI TP3 L

D5 DONE (1) H (IF SET)

)

08-1728

Figure 5-3 Waveforms for IOT 6505 (Read Status)

When the printer address is decoded, there is a match, and INTERNAL I/O L is asserted. At the same
~ time, D1 IOT 5 L is asserted, CO L is asserted, and C1 L is asserted. Asserting CO and C1 sets up the
condition for transferring the data, DATA (0:11) L, to the accumulator from the controller transceivers. The actual gating of the status lines takes place when D1 IOT 5 L is asserted. Asserting D1
IOT S L also causes D5 DONE (1) H to be negated at clock time TP3 (D1 TP3 L asserted).
5.3.4

Write Status (I0T 6506)

Observe the controller block diagram in Figure 5-1 and the corresponding IOT 6506 waveforms in
Figure 5-4.

When the printer address is decoded, there is a match, and INTERNAL I/O is asserted. At the same
time, D1 IOT 6 L is asserted and CO L is asserted. The combination of CO L asserted and C1 L negated
is the condition for transferring the current contents of the accumulator into the controller via the data
lines, DATA (0:11) L. The data applied to the controller transceivers becomes D2 DATA (0:11). Of
these 12 signals, only five are applied to the inputs of the status register flip-flops. These lines are
labeled D2 DATA (5, 8,9, 10, 11) H.

5-7

TPO3H

170 PAUSE L

[
fe——15pSEC——»]
|

INTERNAL I/0 L

D1 IOT
6 L

CoL

ciLDATA (0:11).L Z——___] STABLEE

DI TP3
L
D4 DONE FLAG H

E1-5

D5 CLK DONE H

D5 DONE (1) H

|
08-1819

Figure 5-4

Waveforms for IOT 6506 (Load Status)

At clock time TP3, the D2 DATA signals are clocked into their corresponding status register flip-flops,
and D3 SET DONE H is asserted, so that D5 DONE (1) H is asserted. Printer operations that now
take place depend on the stored content of the status register as described below:

IfD2DATA 10 H is asserted, then D3 LIFT BLK (1) H is now asserted, so that LIFT BLK

If D2 DATA 11 H is asserted, then D3 INT ENBL (1) H is asserted.

1If D2 DATA 5 H is asserted, then D3 LEFT PAPER (1) H is asserted and D3 LEFT
PAPER (0) H is negated. Similarly, if D2 DATA 8 and 9 are asserted, D3 BAIL DISENGAGE (1) H and D3 LIFT RED (1) H are asserted.

L 1s asserted. When LIFT BLK L is asserted, the printer ribbon is lifted to the up position.

When D3 INT ENBL (1) H and D5 DONE (1) H are both asserted, then INT RQST L is also asserted.
5.3.5

Print Character (I0T 6504)

Observe the controller block diagram in Figure 5-1 and the corresponding IOT 6504 waveforms in
Figure 5-5.

When the printer address is decoded, there is a match and INTERNAL I/O L is asserted. At the same
time, the following signals are also asserted:
D1IOT 4L

D1 10T 2, 3, 4L
D1 I0T 2, 3, 4, TH
b

COL

The combination of CO L asserted and C1 L negated is the condition for transferring the current
contents of the accumulator into the controller via the data lines, DATA (0:11) L. This particular data
represents a printer command (1 of 96 characters).

5-8

INTERNAL 1/0 L

—{

'
) ——

(¢

__((

(

cn__r‘S'f
|
—_J STABLEE——
DATA (0:11) L

‘

e 2 usEC —————»|
]

STROBE ONE SHOT
CHARACTER

STROBE L

D4 DONEFLAG H

D5 CLK DONE H

(¢

D5 DONE1 H

D3 CLEAR DONE L

) 7

~_] STABLE

DI TP3 L

(¢
N

D (1024:1/2 L)

pt1oT4L- L[
coL

TPO3H

S
__((

170 PAUSE L
‘

TPO3H

_ [le——15p5eC ——->f]

r—%‘fi

L—DEPENDS ON TIME REQUIRED
FOR PRINTER OPERATION

08-1818

Figure 5-5 Waveforms for IOT 6504 (Print Character)
When timing pulse TP3 occurs, TP03 H is asserted, so that D1 TP3 L is asserted. The combination of
D1 TP3 L and D1 IOT 2, 3, 4 L clocks the data into the LQPDB data buffer, with the result that the
corresponding bits of D (1024:1/2) L are asserted. In this case, D64 L is the MSB and D1 L is the LSB
(Figure 4-6).

The leading edge of D1 TP3 triggers the settling delay one-shot. The high output of the settling delay
one-shot clocks D1 IOT 4 L into the corresponding instruction storage flip-flop, whose one output is
applied toaNAND gate. The low output of the settling delay one-shot is labeled D3 CLEAR DONE
|

L and is also asserted at this time, causing D5 DONE (1) H to be negated.

When the settling delay one-shot times out, its high output goes low, triggering the strobe one-shot.
as CHARACTER STROBE
The high output of the strobe one-shot gates D1 10T 4 L into the printer
L. The CHARACTER STROBE transfers the printer command into the printer. The decoded command initiates movement of the print wheel to the programmed character, whereupon the print hammer is energized to actually print the character. While the print wheel is moving, the printer negates the
CHARACTER READY line and ignores any further print character commands. Upon completion of
the printing operation, the CHARACTER READY bit is asserted, thereby causing D4 DONE FLAG
H to be asserted. After this signal, D5 DONE (1) H is generated in the same manner as described for
the Restore function.

5.3.6

Move Carriage (10T 6503)

Observe the controller block diagram in Figure 5-1 and the corresponding IOT 6503 waveforms in
Figure 5-6.

5-9

TPO3H

[[fe——1.5uSEC ——]
|
1/0 PAUSE L

INTERNAL 1/0 L

(¢

=5
((

((

DATA (2:11) L //////I STABLE V///////////////////////////%: r/
D (1024:1/2 L) 22227

{

STABLE

:’L

-4 §

]

DI TP3 L

—

|
prroT3L L
coL

TPO3H

((

¢ (

]

.
((

D3 CLEAR DONE L

D5 DONE (1) H

CARRIAGE

STROBE ONE SHOT
STROBE L

2 uSEC

|
~

4§

D4 DONE FLAG H

. S—-l

D5 CLK DONE H

LDEPENDS ON TIME REQUIRED
FOR PRINTER OPERATION

08-1815

Figure 5-6 Waveforms for IOT 6503 (Carriage Motion)
Circuit operation for this instruction is the same as that for IOT 6504 (Print Character) except that
CARRIAGE STROBE L is asserted and the CARRIAGE READY status line sets the DONE flag.

P
-

3.3.7 Move Paper (10T 6502)
Observe the controller block diagram in Figure 5-1 and the corresponding IOT 6502 waveformsin
Figure 5-7.

Interpretatlon of the data bits for carriage movement is illustratedin Figure 4-5.

Circuit operation for this instruction is the same as that for IOT 6504 (Print Character) except that
RIGHT PAPER STROBE L is asserted when the strobe one-shotis triggered and D2 DBR 11 (1) H is
negated, except that the PAPER RIGHT READY status line sets the DONEflag. Interpretation of
the data bits for paper movement is illustratedin Figure 4-4.

5.3.8 Read Data Buffer into Accumulator (IOT 6501)

When the printer addressis decoded thereis a match, and INTERNAL I / O is asserted (Figure 5-1). At
the same time, D1 IOT 1 L is asserted, as are CO L and C1 L. The combination of CO L and C1 L both
assertedis the condition for clearing the accumulator and then reading data from the controller data
buffer into the accumulator. In this case, D2 DBR 0(1) H through D2 DBR 11(1) H are gated onto the
Omnibus via the transceivers when D1 IOT 1 L goes low.
5.3.9 Skip on Done (IOT 6500)
When the printer addressis decoded, thereis a match, and INTERNAL I/O L is asserted (Figure 5-1).
Concurrently, D1 IOT O L is asserted. If DONEis already set [D5S DONE (1) H asserted], then SKIP L
is asserted and applied to the PDP-8 via the Omnibus.

5-10

TPO3H

e——15usEc—
1/0 PAUSE L

MD (03:08) MATCH

(§

»7

((

)

((

(¢

;(fi
)

~_|

DI TP3 L

D3 CLEAR DONE L

D5 DONE (1) H

D5 CLK DONE H

2 pSEC

[

¢
|

{ ¢

—»f

STROBE L

D4 DONE FLAG H

(

STROBE ONE SHOT

RIGHT PAPER

g ¢

STABLE

] STABLEE——

D (1024:1/2 L)

S ¢

DATA (2:11) L

TPO3H

coLTM LT
CiL

“(

pr1oT2L"

f
|

INTERNAL I/0 L~

TPO3H

]

(‘ f

LDEPENDS ON TIME REQUIRED
FOR PRINTER OPERATION

08-1816

Figure 5-7

Waveforms for IOT 6502 (Paper Motion)

CHAPTER 6
SERVICE

6.1
6.1.1

INTRODUCTION
Scope

This chapter describes preventive and corrective maintenance procedures for the LQP8-E printer.
Helpful hints to facilitate fault isolation are provided, wherever possible, and step-by-step procedures
to remedy field repairable malfunctions are given. Load and run procedures for the LQP8-E diagnostics are also described. A troubleshooting flowchart is provided in Appendix E as a quick reference for
isolating problem areas.

6.1.2

Maintenance Plan

Except for mechanical alignment, repair of the LQP8 is carried out on a module swap basis. All PCB:s,
as well as the carriage assembly, are field replaceable. Printers requiring re-stringing of the carriage
drive cable or replacement of the carriage drive motor are to be swapped out of service and returned to
a depot repair facility for repair. Preventive maintenance (cleaning and lubrication) is to be carried out

6.1.3

on a non-scheduled basis.
Resources

All maintenance is accomplished using the parts and materials provided in the spares kit contained at
each applicable field service branch. A list of the materials included in this kit is given in Table 6-1.
Table 6-1

Recommended LQPS8 Field Service Branch Spares

Part/Material

Power Amplifier PCB
Carriage Amplifier, PCB
Servo PCB

Lever, Manifold
Hammer Energy Switch
Cover Open Switch
|
Logic 1 PCB
Mother PCB
Transducer PCB
Carriage Assembly
Shaft, Carriage

Logic 2 PCB
1300 Alignment Tool
T15 Torx Driver
T9 Torx Driver
328 Lamp (6)

Fuse 3AG5A (3)
Fuse 3AG7A (3)
Fuse GBBS (3)
Interface Module

Hammer Armature Assembly
Pickup, Magnetic
Rear Carriage Bearing
Ribbon Lift Assembly

Ribbon Lift Coil Assembly | Ribbon Out Sensor
Carriage Home Sensor
Gear, 85T Spur

Platen Knob

Set Screw

Bail Arm, Right
|

Lever, Pressure Release
Bail Arm, Left

6-1

6.2

PREVENTIVE MAINTENANCE

6.2.1
Preventive Maintenance Schedule
Thereis no rigid schedule for preventive maintenance. It is to be completed durlng service calls and

then only when it is evident that no lubrication has been carried out in the last six months. If no service
calls have been made on a given printer in a one year tlme period, then a special trip should be made to
clean and lubricate the printer.
6.2.2 Materials Required
Cleaners and lubricants required for the preventive maintenance procedures are listed below.
Isopropyl Alcohol 91%
Molycote 557

Multipurpose Lithium Grease
- Polyoil Type 280 (8¢¢)

Loctite

Thickness Gauge

Platen Cleaner 3.79 (1 gal)

Teletype Grease

6.2.3
Customer Performed Equipment Maintenance
Customer maintenance of the LQPS is limited to removal of foreign materials from print wheels,
platen, or ribbon lift platform. This includes foreign materials that mlght be introduced by spillage or
dirt and dust creating factors.
6.2.4
Field Service Preventive Maintenance
Preventive maintenance executed by field service personnel consists of three act1v1t1es 1nspect10n
cleaning, and lubrication.

6.2.4.1

Inspection - To inspect the LQP8-E printer, proceed as follows:

Remove power from the LQP8- E by pressing the system ON/OFF switch or by disconnecting the ac power cord going to the printer power supply (base of cabinet).

Remove front panel and top cover to gain access to printer mechanisms
and PCBs.

Inspect all printer subassemblies for signs of wear and lose, broken, or charred components.

Check the platen system for looseness or wobble.

Check the carriage system for looseness, wobble, and accumulation of foreign material on
the slide rails that could lead to erratic carriage movement.

Check the carriage drive cable thoroughly for signs of fray or wear.

Remove the forms tractor, platen, ribbon cartridge, and print wheel. Inspect each item for
signs of wear. This completes the inspection process.

6.2.4.2

Cleaning — Most areas of the LQPS8-E are to be cleaned using alcohol saturated wipers. Exceptions are the platen (which should be cleaned while removed from the printer), the platen pressure
rollers, and paper bail tires — all of which are made of rubber. Use a platen cleaner such as Fedron to
clean these parts.

6-2

When cleaning all non-rubber components, proceed as follows:

1.
2.

Using alcohol saturated wipers, thoroughly clean the printer to remove the accumulation of

paper residue, ink, and dust.

Pay special attention to cleaning the slide rails and pulley to ensure free or non-restrictive

movement of the carriage assembly.

To clean the platen and other rubber parts, the platen cleaner must be used.
|
CAUTION
Ensure that the platen cleaner does not come in contact with surfaces other than those rubber parts mentioned above. Platen cleaner may be harmful to
certain finishes.

Clean the platen and other rubber surfaces with a wiper saturated with platen cleaner.
CAUTION
Do not drop platen when cleaning. Warpage may
result and introduce erratic printout when
reinstalled.

6.2.4.3

Lubrication — Lubricate the inspected and cleaned printer in accordance with the following

conditions:

Lubricate approximately every six months for printers in normal daily use.
CAUTION

Do not lubricate too often. Too much lubricant can
be worse than none at all.

Lubricate a printer that has been sitting idle for an extended period (such as a branch loaner)
before putting in use. Areas to be lubricated are: carriage system, carrier system, and platen.

Lubricate the carriage system (Figure 6-1) as follows:
d.

Carriage Rails (A) - Clean these items with alcohol wipers only
Carriage Rail Bearings (B) - Spray with Molycote and manually oil on each side of

carriage rails.

Carriage Pivots (C)- Apply one drop of polyoil to the prOt on each side of the carriage
frame.

Carrlage Pivot Spring Loops (D)
- nghtly grease the end loops and posts on the p1vot
spring on each side of the carriage frame with lithium grease.

Ribbon Base Plate Plvots (E)
- Saturate the felt washer on each end of the base plate
pivot shaft with polyoil.

6-3

@
Figure 6-1

g.
h.

Carriage System Lubrication Points

M-0666

Ribbon Drive System (F) - Apply one drop of polyoil to the drive and idler gear shafts

and to the drive key slot.

Hammer Armature Pivots (G) - Remove the rubber cup and fill the grease chamber

with lithium grease. Replace rubber cup when finished.

Print Hammer (H) - DO NOT lubricate this item. If customer uses cloth ribbon, ensure
that hammer 1is clean.

Lubricate the carrier system (Figure 6-2) as follows:
1.

Paper Feed Roller Shaft Pins (A) - Lightly grease the eight (8) pressure roller shaft pins with
lithium grease.

Platen Position Lever Detent Plate (B) - Lightly grease the inside of this plate with lithium
grease.

Platen Position Slide Plates (Carrier Frame) (C) - Lightly grease exposed slide surfaces
(lever moved limit to limit) and all points of contact with pivots, eccentrics, guides, etc., with
lithium grease.

M1-0478

Figure 6-2

Carrier System Lubrication Points

Platen Position Torque Shaft Ends, Bearing Surfaces, and Spring Loops (D) - Lightly gr}é‘a“se
|

these points with lithium grease.

Paper Release Lever Tab Ramp and Shaft Pivots (E) - Lightly grease these points with
lithium grease.

Paper Release Torque Shaft Pivots and Arm Slots (F) - Lightly grease these points with
lithium grease.

Paper Bail Pivots (G) - Lightly grease these two points with lithium grease.

Lubricate the platen (Figure 6-3) as follows:
1.

Paper Feed Idler Gear (A) - Inspect the large felt washer behind this gear. If it is becoming

white in color, saturate with polyoil.

Platen Release Tab Arms (B) - Lightly grease the contact area between these arms and the
carrier side frames.

- Platen Hubs (C) - Apply one drop of polyoil to the bore of the hub at each end of the platen.

(

M1-0479

Figure 6-3

6.3

Platen Lubrication Points

DIAGNOSTIC FUNCTIONAL DESCRIPTION

J—

6.3.1
Overall Performance Test
Diagnostic test DHLQAis used to check the overall performance of both the controller and printer.
ThlS diagnostic has two main parts:

Internal logic tests - These tests are run with the LQPS-E printer placed off-line and serves
to exercise the controller (M 8366) circuits.

| 2.

Dynamic printer tests - These tests are executed with the LQPS-E prin‘t-er on-line and

6.3.1.1

Controller Diagnostic Test — For this check, the printer must be placed off-line. Do this by

dynamically check all printer operational capabilities.

removmg the printer top front cover. The controller dlagnostlc test is now actlvated by following the
steps in Paragraph 6.3.1.3.

Once initiated, the internal logic test loops 4096 times and, provided that there are no errors, the
message END OF LOGIC TESTis displayed on completlon of the test.

If an error occurs, the internal logic program displays “DHLQA FAILED.” Also, the following program parameters are displayed: PC=XXXX, AC=XXXX, MQ=XXXX, FL=XXXX.

6.3.1.2

Printer Dynamic Diagnostic Tests - For these checks, the printer must be placed on-line. Do

this by replacing the front cover on the printer. The printer dynamic diagnostic tests can now be
activated by following the steps given in Paragraph 6.3.1.3.

6-6

(

6.3.1.3 Diagnostic Load and Run Procedure
--To load and run prmter diagnostic DHLQA, proceed as
follows:
1.

With system power ON, place diagnostic diskette in Drive 0 (left port).

Close drive door.

Press START switch then observe that the VT52 displays the following:
0123

‘Type any key on keyboard, then wait for the VT52 to display the following:

When running internal logic test, proceed to step 6. When running dynamic p'r‘inter tests,
proceed to step 8.

Using the keyboard, type any key and observe the following message:
R DHLQA (or whatever version software installed)
Press the RETURN key on the keyboard. The dlagnostlc now beglns automatically at
address 0200z (internal loglc test).

Type the followmg message on the VT52 display»:
GET SYS DHLQA

Press the RETURN key.
NOTE
At this point, service personnel may wish to alter cer-

tain diagnostic program constants in order to run the
tests on 21.59 cm (8-1/2 in) rather than 35.56 cm (14
in) paper. Altering of constants is covered in Paragraph 6.3.2.7.
10.

Type the following message on the VT52 display:

START 0203
11.

Press the RETURN key; then, while holding the CTRL key down, type the letter G.
Check that VT52 dlsplays the following:

- SR=
13.

Type the number of the desired dynamic printer test [0045-0057 (e.g., swirl pattern is 51g)].

14.

Press the RETURN key. The selected diagnostic test is now executed on the printer.

6-7

6.3.1.4

Manual Entry of Characters for Printing - Printing of operator-selected characters is accom-

plished using dynamic diagnostic test 56g. To print a line of desired characters, proceed as follows:
1.

2.
|

Select diagnostic test 565 using the steps in Paragraph 6.3.2.3.

Enter a line of desired character via the keyboard. Each characteris displayed on the VT52
display as it is typed.

When the desired line of characters is entered and displayed, press the RETURN key. The

6.3.1.5

Halting an In-Process Dynamic Diagnostic Test- To stop an in-process printer diagnostic test,

6.3.1.6

Restartmg Dynamic Diagnostic After Halt - To initiate another diagnostic following a halt,

displayed character string is now echoed on the printer.

srmultaneously press the CTRL and T keys on the keyboard.

proceed as follows:

While holding the CTRL key .down type the letter G.

Press the RETURN key; the newly selected diagnostic test is now executed

Enter the number of the desired diagnostic test.

6.3.1.7 Procedure for Modifying the Contents of a Location - To modify a location [e.g., as for 21.59
cm (8-1/2 in) rather than 35.56 cm (14 in) wide paper] proceed as follows:

1. Simultaneously press the CTRL and C keys.
2.

Check that VT52 displays the following:

Type the following message on the VT52:
OD

Press the RETURN key; then check that the VT52 dlsplay executes two line feed
commands

Type the octal notation of the address to be altered; then» press the / (slash) key.

Check that the location address and its contents are displayed on the VT52. For example, if
a line length constant of 0204is storedin location 0134;, then the message displayed on the
VT52is:

0134/0204

Enter the new parameters in the selected location by typing the desired values on the key-

board. [For example, location 0134 is changed from 02045 to 0110s to run the diagnostic on
21.59 (8-1/2 in) paper. Similarly, location 15345 is changed from 3044z
to 17005 to run test
475 on 21.59 (8-1/2 in) paper].

Press the RETURN key. The new parameters are now entered in the selected location.

See step 10 in Paragraph 6.3.1.3 for restart procedure.
6-8

6.4

FUNCTIONAL SECTION FAULT ISOLATION

6.4.1
Specific Tests and Descriptions
When reported failures indicate erratic printer behavior or degraded print quality, a total performance

check can be achieved quickly through use of selective diagnostic tests for specific operations or characters. These tests completely exercise the printer. A breakdown of the dlagnostlcs and the operational
capabilities they test are as follows:
1. -

Test 45 - Horizontal spacing. This test checks that the carriage is being positioned by the
programmed amount before printing each dot.

Test 46 - Vertical spacing. This tests checks that the paper is advanced by the programmed
amount prior to printing a 5.08 cm (2 in) line of underscores.
Test 47 - Carriage positioning. This test checks that the carriage is belng pos1t10ned
correctly.

Test 50 — One line/character. This test checks the print velocity of the printer.
Test 51 - Swirl pattern. This test checks the printing of all characters on the print wheel.
Printing of a dozen lines is sufficient to determine the quality of print. Line feed problems
can also be detected during this check by observing the relationship between acute accent
and underscore characters.
Test 52 - Ribbon lift/drop with overprint. This test checks the ribbon lift capabilities of the
printer.
Test 54 — Nonprinting character codes. This test checks that none of the ASCII control
characters can cause an erroneous character printout. For all control characters, the lower
case w is printed.

Test 56 — Operator generated print line. This test allows the operator to enter a line of
characters on the display for subsequent printout on the LQPS. To further evaluate print
quality, use this test as follows:
a.

Enter and then print a line of capital Zs. The observed printout can then be used to
check platen height settings.

Enter and then print a line of capital Hs. The observed printout can then be used to
check print wheel to hammer alignment.

6.4.2 Fault Isolation
Table 6-2 summarizes catastrophic failure modes and remedial actions for the LQPS8-E printer. Table
6-3 summarizes degraded printout failure modes and related corrective actions.
6.5

TROUBLESHOOTING

6.5.1
Initial Analysis
In general, printer malfunctions can be considered as falling into one of two broad categories:
1.

Printer fails to print - Such catastrophic faults usually stem from electrical or electronic
malfunctions such as no ac power, a bad power supply, or defective PCBs.

Printed data is erroneous or degraded - Failures falling in this category generally are caused
by misalignment of one or more of the numerous LQP8-E mechanical adjustments.

6-9

Table 6-2

Sympton

Catastrophic Failure Troubleshooting Chart

Probable Cause

Action

Printer does not power | Low ac line voltage/ current

Reference

Check line power

up and no indicator

lamps light
Defective power cord or not

Plug in or replace

plugged in

PRINTER READY

Blown power supply fuse(s)

Replace fuse(s)

Power supply defective

Replace power supply

Faulty controller PCB

Swap out controller PCB

Faulty controller PCB

Swap out controller PCB

lamp lights but printer

exhibits no carriage

Defective interface cable or

Check connections and repair

and/or print wheel

not properly seated in

or replace interface cable as

movement

connectors

required

Printer goes into and

Low voltage output from

Adjust power output

remains in CHECK

power supply

Diablo
Power

Supply
Manual

Carriage overshoots on | Low voltage output from
long slews

Adjust power output

power supply

Diablo
Power

Supply
Manual

Power supply output

Carriage amplifier PCBs

normal but no carriage

defective

Repair or replace PCBs

movement

Power supply output

Print wheel PCBs defective

normal but no print

wheel movement

6-10

‘Repair or replace PCBs

Occasional and inconsistent problems such as the printer going into check or a broken mylar ribbon
are special cases, that is, they do not fall in either of the above categories. In most instances, however,
the field service representative can begin the analysis by placing the observed fault in either of the
previously mentioned two categories.

Printers receiving normal power and yet falling in the fails-to-print category may have a faulty controller PCB or the interface cabling may be disconnected /defective. A swap out of controller PCBs in
the PDP-8, coupled with a check of interface wiring connections, may correct such malfunctions. The
internal logic test portion of the printer diagnostic test should be run to evaluate controller PCB
operation prior to swap out. If the printer still fails to print following replacement of the controller
PCB, then the printer PCBs should be swapped out, beginning with the logic 2 PCB.
If the printer exhibits some movement (e.g., carriage and print wheel motion) but still does not print,
the fault most likely lies in the printer PCB (Figure 6-4). If the printer still fails to print, following a

swap out of the print wheel amplifier PCB, it could mean that the hammer armature coil is
open/burned out and must be replaced. In such case, the entire carriage assembly must be replaced.
Figure 6-4 indicates the main role(s) played by each of the printer PCBs and as such is useful in
determining which PCB should be swapped out for any given malfunction. For example, if there is
print wheel and hammer movement, but no carriage motion, then the carriage amplifier and servo
PCBs should be swapped out. (Refer to Figure 6-16 for further PCB reference locations.)

Troubleshooting information at the end of this chapter breaks down all failure types in greater detail.
Symptoms and remedial actions are listed for all malfunctions in the fails-to-print category. For malfunctions in the degraded print category, sample printout errata (related to the dynamic diagnostic
tests) are shown. The related adjustment procedure for correcting the degraded print quality is also
referenced.

6.5.2

Alignment and Adjustment

The subsequent paragraphs describe the alignment procedures to be carried out on the LQP8-E printer. The majority of these adjustments require use of the special alignment tool included in the spares
kit. Figure 6-5 shows an outline of the tool and indicates the intended use of its various mechanical
features.

The following conditions are set forth as prerequisites for carrying out alignment procedures involving
|

the special tool.

Power - Power is to be applied when making these adjustments. Power is necessary to
electrically detent the print wheel and carriage servo motors. It is also necessary for cycling
the printer through a Restore sequence when required.

Platen - A defect free platen is to be installed for‘ all platen adjustments.

Ribbon - Ribbon adjustments are to be made with a mylar ribbon installed.

Platen position (manifold) lever - This control is to be positioned fully forward for all
adjustments.
CAUTION
|
To prevent damage to the printer, always remove the
alignment tool from the print wheel motor shaft
before initiating a Restore sequence.

6-11

PRINTWHEEL

TRANSDUCER

AMP (H)

PCB (G)

REAR PCBs

SIGNAL CABLE
RECEPTACLE

CARRIAGE
AMP PCB (D)

SERVO PCB (C)

LOGIC BOARD 2

PCB (B)

LOGIC BOARD 1

PCB (A)

8044-16

Print Wheel Amplifier PCB (H)
e

Print wheel power transistors

Ribbon feed circuit

Hammer energy/Drive circuit

Servo PCB (C)
D/A Converter

Main summing circuit. Generates servo
error signal for print wheel and carriage
Generate C and D pulses

Transducer PCB (G)
e

Generates transducer signals

Generates carriage position
wheel position signals

Carriage Amplifier (PCB) (D)
®
Power monitor circuit

Feedback
carriage
and print

circuit for print wheel and

Processes hammer energy commands

Logic 2 PCB (B)
System subclock (B,C)

Paper feed circuit

(Carriage power transistors

Program memory, program counters, com-

parators, scratch pad, table ROM, instruction decode, operating registers A and B,
adders, storage register

Logic 1 PCB (A)
Interface

Processes input commands and data
Generates ready and status signals

Figure 6-4

Printed Circuit Board Layout and
Function Description
- 6-12

CARD GUIDE ALIGNMENT TAB

/ HAMMER SLOT
@ CARRIAGE HOME
ADJUSTMENT
TAB

CARRIAGE HOME
ALIGNMENT TAB

@ CARD GUIDE
ADJUSTMENT TAB

PLATEN

ALIGNMENT SLOT

ADJUSTMENT TAB

RIBBON HEIGHT
ADJUSTMENT SLOT
08-1740

Figure 6-5

6.5.2.1

follows:

Multipurpose Alignment Tool

Print Wheel to Hammer Adjustment - To align the print wheel with the hammer, proceed as

Apply power to the printer, and verify completion of Restore sequence.

Remove any paper from the carrier, remove the ribbon cartridge, and remove the print

wheel.

Install the tool firmly on the print wheel motor shaft, and ensure that it is properly seated
with its alignment slot Bl centered over the print wheel alignment tab. Rotate the print
wheel motor and tool to bring the tool’s hammer slot B2 to the top in front of the print
o

hammer.

to detent the print
Block the carriage home sensor (insert a piece of dark paper in its slot)

wheel motor.

Manually push the hammer forward lightly, until its face enters hammer slot B2 on the tool
(Figure 6-6). If the hammer slides easily into the tool slot without contacting the sides of the
slot, print wheel to hammer alignment is correct. Therefore, no adjustment is necessary. If
the hammer face contacts the tool surface, continue with this procedure.

6-13

PUSH HAMMER
IN SLOT

- @ :j:/LAG

LOCTITE
HERE
HOLD HERE

WITH 174" WRENCH
08-1741

Figure 6-6

Print Wheel-to-Hammer Alignment Positions

Place a 1/4 inch open wrench on the nut of the print wheel motor shaft and hold to prevent

the shaft from turning. Move the tool, as necessary, to achieve proper alignment with the

hammer.

|
CAUTION
In this step, the tool is moving the print wheel locator
tab/sensor flag on the motor shaft. This part has
been bonded to the shaft with Loctite. If it is necessary to flex this part to break the Loctite bond, exercise care not to deform the part. Re-bond with
Loctite when alignment has been completed. Care is
essential in this step since movement of the home sensor flag (relative to the home sensor transducer) may
necessitate carrying out the adjustment procedure in
Paragraph 6.5.2.9.

Repeat step 5 to verify proper print wheel to hammer alignment; then, remove carriage
home sensor block.

6.5.2.2

Platen to Print Wheel Alignment Procedure- This adjustment affects both platen height posi-

tion and card guide position. Therefore, both of these adjustment procedures must be carried out after
aligning the platen to the print wheel. Proceed as follows:
1.

Apply power and loosen the card guide mountlng screws and lower the gulde as far as it will
go.

WARNING
If the alignment tool is installed prior to applymg
power, the print wheel motor shaft will attempt to
spin to the HOME position with the tool attached.
The resultant action could cause both personal injury
and major damage to the carriage area of the printer.

6-14

Tilt the print wheel motor forward and verify that the alignment tool (mounted on the print
wheel shaft) clears the card guide completely (Figure 6-7). Tilt it back again.

MANIFOLD LEVER FORWARD

ECCENTRIC SLIDE
CLAMP SCREWS

PLATEN

REAR

ECCENTRIC

FRONT

ECCENTRIC
IDLE GEAR
MAY BE REMOVED

(RIGHT SIDE VIEW)
’

F igure" 6-7

08-1742

Platen-to-Print Wheel Adjustment

Place the carriage servo switch (located near top edge of the carriage power amplifier, PCB,
slot D)in the OFF position.

4. Using a 1/4 inch open end wrench, loosen the locknut on the front eccentric, position the
front eccentric on each end of the carrier assembly, and set each to its mldrange (lobe facing
away from you).
|

5. Move the carriage as far left as it will go. Tilt the print wheel motor forward and verify the
following relationship between the platen and the tool:

- 7-,

The miniumum platen setting is when the tool’s platen adjustment tabs (C) lightly

The maximum platen setting is when clearance of no more than 0.0076 cm (0.003 in)
can be measured between the tabs (C) and the platen surface.

touch the platen surface with a barely perceptible drag.

Tilt the print wheel motor back and move the carriage as far as it will go; then, tilt the print
wheel motor forward again and check the platen-to-.tool relationship. If the platen adjustment is within the limits stated above, and is equal for both ends of the platen, then no
adjustmentis necessary. If the print wheel to platen setting is out of tolerance, continue with
the following steps.

Loosen the two rear eccentrlc shde clamp screws and the screw for the rear eccentrlc itself,

8. Adjust the rear eccentric, using a 7/16 inch open end wrench, to brlng the platen clearance
to within the limits specified; then, tighten the slide clamp screws.

6-15

9.
10.

Move the carriage to the opposite end of the platen and check for proper clearance.

Repeat steps 8 and 9 until the clearance on each end of the platen are within specified limits

and are equal.
11.

Tighten rear eccentric clamp screws when adjustment has been completed.

6.5.2.3 Card Guide Height and Position Adjustment When this procedureis carried out immediately
after the platen to print wheel adjustment, it can be assumed that the two card guide mounting screws
have already been loosened and the card guide lowered. If the card guide has not been lowered, loosen
the two mounting screws and lower the guide as far as it will go. Also, ensure that the alignment tool is
positioned firmly on the motor shaft. To adjust the card guide position, proceed as follows:
1.

Push the print hammer into the hammer slet (B2) on the tool, and hold it there (Figure 6-8).

.O05MIN.

CARD GUIDE

.O05MIN.

HAMMER

RIBBON GUIDE

PLATEN

08-1743

Figure 6-8

Card Guide Height Adjustment

Raise the card gulde gently, until its top edge contacts the undersides of card guide align-

ment tabs, D1 and D2, with equal pressure.

Release the hammer and, while holding the card guidein ‘contact W1th the tool tlghten the

card guide’s two mounting screws.

Using a 0.0127 cm (0.005 in) plastic shlm check for no-drag sh1m clearance between the card
guide and the ribbon guide posts on both sides of the carriage. Normally, this dimensionis

~set by the depth of the ribbon guide post tabs. Shim drag indicates the card guide has

become tilted, in which case its support arms should be gently reformed to achieve proper
clearance around the ribbon guide posts.

Using the 0.0127 c¢cm (0.005 in) plastic shim, check for no-drag clearance between the card

guide and the platen along the full length of the platen.

6-16

6.5.2.4
1.

Ribbon Height Adjustment — To adjust the ribbon height (Figure 6-9) proceed as follows:
Manually position the carriage assembly to the left of the carriage drive motor.

Using a Torx driver, loosen (do not remove) the front slide rail hold down screws; then,

move the slide rail to the left to disengage it from the carriage assembly.

Using long nose pliers, remove the two retainer clamps from beneath the front slide rail

bearing assembly (Figure 6-9).

Remove the slide rail bearing assembly to gain access to the ribbon lift coil mounting screws
(Figure 6-10).

Place a 5/32 inch box and wrench on one of the two lock nuts (Figure 6-10), then use a 3/16
inch nut driver to loosen the screw a couple of turns. Repeat loosening procedure for the
second bolt.

Using a 3/16 inch wrench, loosen ribbon lift eccentric locking screw (Figure 6-9).

Remove print wheel and install alignment tool firmly on print wheel shaft.
Install a mylar multistrike ribbon; then, rotate tool so that wide gap (E) at base of tool is
positioned opposite print wheel hammer.

Manually push up on ribbon lift grommet (Figure 6-9) so that grommet contacts ribbon left
eccentric.
10.

Using a slotted head screwdriver, rotate eccentric so that a mylar ribbon appears in notch

(E) on alignment tool; then tighten the ribbon lift eccentric locking screw.

NOTE

Lobe of eccentric must be facing front of machine.
11.

Insert a 0.02032 cm (0.008 in) plastic shim between ribbon lift coil and pole plate.

12.

With ribbon lift grommet clamped against eccentric, energize ribbon lift coil (see
Diagnostics).

13.

Place a 0.02032 cm (0.008 in) plastic shim between ribbon lift coils and pole plate (Figure610).

14.

Place 5/32 inch wrench over one of the two lock nuts.

15.

While holding rear of ribbon lift plate down [with 0.02032 cm (0.008 in) plastic shim in
place], use a 3/16 inch nut driver to exert upward pressure on ribbon lift coil mounting bolt;
then tighten the bolt. Repeat steps 14 and 15 for remaining ribbon lift mounting bolt. The
clearance between top of ribbon lift coils and ribbon base plate should now be exactly
0.02032 c¢m (0.008 in).

16.

De-energize ribbon lift coil by pressing the RETURN key on the keyboard.

6-17

SLIDE RAIL
BEARING

CLAMPS

SLIDE RAIL
BEARING

RIBBON

08-1793

CARTRIDGE

RIBBON
TOOL

BRACKET

SCREWS

SLIDE RAIL

'BRACKET

\
RIBBON LIFT

GROMMET

ECCENTRIC

| ECCENTRIC LOCKING

SCREW
POLE PLATE

SLIDE RAIL

BEARING

RETAINER CLAMPS

RIBBON LIFT COIL

(See Note)

MOUNTING SCREWS
SLIDE RAIL

1/'\

NOTE:

On some printers the mounting screws
are inserted from the rear anda nut plate is
mounted at the front.
08-1794

Figure 6-9

Ribbon Height Adjustment

RIBBON
LIFT
PLATE

RIBBON
LIFT COIL

RIBBON
LIFT COIL
MOUNTING

SCREWS

Figure 6-10 Exploded View of Ribbon Lift Assembly

17.

While holding the ribbon lift grommet against ribbon lift eccentric, measure the gap between
ribbon lift coils and pole plate. The gap should measure between 0.0076 and 0.02032 cm
(0.003 and 0.008 in). Also, top of mylar ribbon should be visilein notch (E) on alignment

tool. If not, repeat procedurein steps 10 through 16.
18.

6.5.2.5

On successful completion of procedure, remove allgnment tool and replace slide rail bearing
assembly and slide rail by reversing procedurein steps 1 through 4.
Carriage Home Adjustment - To adjust the position of the carriage home sensor flag (Figure

6-11), proceed as follows:
1.

With power applied to the printer, initiate a Restore sequence.

Insert alignment tool between printer mamframe casting and the carriage frame (Flgure 611).

Us1ng a feeler gauge, measure the distance between tool tabs F1/F2 and mainframe casting.
Check for a maximum cumulative distance between tool tabs and mainframe casting of not
more than 0.02032 c¢cm (0.008 in).

If gap exceeds 0.02032 cm (0.008 in), loosen eccentric locking screw, then adjust eccentric for
proper gap.

Tighten eccentric locking screw following adjustment.
6-19

-<— CARRIAGE

FRAME

) FRONT BEARING

——f‘

@—

)

ECCENTRIC (SEE NOTE)

CARRIAGE HOME SENSOR FLAG

08- 1791

NOTE:

Excentric may have slotted head or
TORX head on some printers.

Figure 6-11

Carriage Home Adjustment

6.5.2.6 Hammer Armature Gap Adjustments - To adjust the hammer armature gap (Figure 6-12),
proceed as follows:
1.

Remove ribbon cartridge and swing platen adjust lever fully forward.

Install a print wheel and then align one of the print wheel character petals with the print
hammer.

Hold the hammer armature (Item A on Figure 6-12) against the hammer coils (F).

Push the print hammer (C)in as far as it will go to lightly rest the print wheel character petal

(D) against the platen (P)

Measure
the gap between the print hammer (C) and the hammer armature (A). This gap
must be between 0.18542 cm (0.073 in) and 0.21082 cm (0.083 in). If not, loosen armature
assembly mounting screws (G) and position hammer armature for the above gap. After
adjustment, tlghten mounting screws (G).
Measure gap between hammer armature (A) and the armature stop eccentric (B). This gap
must be between 0.11938 cm (0.047 in) and 0.12192 cm (O 048 in). Adjust the eccentric to
achieve this gap setting.

6.5.2.7 Platen Height Adjustment - Platen height adjustment is achieved by rotating the eccentrics
(Item A, Figure 6-13) at each end of the printer. Prior to adjusting platen height, print a line of capital
Zs by using diagnostic test 56. Examine the printed Zs (see samples shown in Table 6-3) to determine
which side of the platenis too low/high. Next, remove the platen and adjust the eccentrics for best
print quality. After adjustment, the platen can be replaced and a new line of Zs printed to see if further
adjustmentis required.

6-20

6.5.2.9 Print Wheel Home Sensor (Transducer) Alignment - This alignment procedure is not routinely
performed in the field. It is to be carried out only under special conditions such as the following:
1.

Random print errors continue to occur following substitution of the carriage assembly.

The transducer needs alignment following the print wheel to hammer adjustment (Paragraph 6.5.2.1).

Alignment of the print wheel home sensor is a three step procedure - print wheel to hammer alignment, transducer gap adjustment, and print wheel even timing signal alignment. The second of these
steps adjusts the amplitude of the transducer output spike, while the third adjusts the relationship of
the print wheel even clock to the leading edge of the transducer square wave. An oscilloscope 1is
required for this procedure.

To align the print wheel to the hammer, apply power and follow the procedure given in Paragraph
6.5.2.1. Rotate the print wheel on the shaft, if necessary, to achieve alignment. Replace the special tool
on the print wheel shaft with a print wheel then continue the procedure by performing the following
‘

steps:

Remove printer covers.

2. Remove power from the printer by pressing the system POWER on/off switch or by dis-4
connecting ac power cord leading to printer power supply.

3. Remove transducer PCB and place on extender board; then re-insert extender board in
transducer slot.

CAUTION

Never remove PCBs when power is applied as damage may result. Further, never apply power with a
PCB removed since this could also prove harmful to
the printer.

Place oscilloscope probe on resistor D20 on the transducer PCB.

5. Re-apply power to the printer.

6. Initiate a Restore operation by pressing the cover interlock switch. (If a diagnostic routine
that loops on the Restore sequence is available, use it rather than manually pressing the
interlock switch.)

7. Observe the oscilloscope for a 600 mV negative going spike each time the interlock switch is
pressed.

8. If the observed spike is less that 600 mV, use a 5/16 inch wrench to loosen the rear nut
(Figure 6-15) on the print wheel transducer; then, manually screw the transducer in or out to
achieve the 600 mV condition.

Lock in position by tightening rear nut.
CAUTION

Be careful not to use too much force since damage to
transducer plastic housing may result. Also, ensure
that print wheel sensor arm does not hit transducer
(Figure 6-135).

6-35

TRANSDUCER
LOCKNUT

TRANSDUCER

TRANSDUCER
ECCENTRIC

%
<

08 - 1792

Figure 6-15

Exploded View of Carriage Assembly

6-36

10.

Remove power from the printer as in step 2.

11.

Remove extender board and disconnect transducer PCB; then, re-insert transducer PCB in
slot G.

12,

Remove logic board 1, PCB and place on extender board; then, insert extender board in slot
A.

13.

Reapply power to the printer.

14.

Connect one of the oscilloscope probes between the channel 1 external trigger input (e.g.,
CH 1 EXT TRIG INPUT if a Textronix model 453 oscilloscope is being used) and print
wheel home check point (chip E25, pin 14 of logic board 1).
|

15.

Place oscilloscope channel 2 probe on print wheel even check point (chip E25, pin 6 of logic
board 1).

16.

Set the oscilloscope controls for the following conditions:
a.

External source (e.g., SOURCE switch to EXT on model 453).

Trigger on negative (e.g., SLOPE to - on model 453).

50 us per screen division (e.g., TIME/DIV switch to 50 on model 453).

17.

Observe the oscilloscope screen; then, initiate a Restore sequence by pressing the cover
interlock switch. Check for a negative going transition in the displayed trace.

18.

Vary the channel 2 position control (e.g., POSITION on model 453) until the negative
transition produced on each Restore sequence appears in the center of the screen.

19.

Set the oscilloscope controls for 20 us per screen division.

20.

Place a 7/16 wrench on the transducer eccentric (Figure 6-15); then rotate eccentric so that
negative transition occurs 160 us after the start of the trace (negatlve transition coincides
with eighth division marker on the screen).
NOTE
Movement of the transducer eccentric will probably
affect the voltage level achieved in steps 2 through 9.
Therefore, the entire procedure must be repeated
until the spike observed in step 8 is 600 mV and the
trace observed in step 20 equals 160 us.

21.

Initiate a series of Restore sequences; ensure that the print wheel stops over letter E after
each restore.

6.5.3 Removal and Replacement
The subsequent paragraphs present a step by step procedure for removing and replacing the carriage
assembly. Figures 6-16 through 6-29 are provided as an aidin identifying parts during the removal and
replacement process.

6-37

6.5.3.1 Carriage Removal Procedure — To remove the carriage assembly, proceed as follows:
CAUTION

Caution must be exercised during the carriage removal /replacement procedure to ensure that the carriage pulley is not unstrung and that the carriage
pulley is not allowed to spin (flip). If the cable is
unstrung, the printer will have to be returned to the
manufacturer for service and repair.

Remove cover, PCB hold-down bracket, and signal cable from the printer.

Remove the two rear logic boards containing heat sinks (Figures 6-16 and 6-17).

Remove signal cable from logic board 1 (Figure 6-16).
Tilt assembly as shown in Figure 6-17 and remove the four screws securing rubber feet.
Remove bottom panel with cord (Figure 6-18).

as many Fastons as necessary, and tie wraps (Figure 6-19).
Remove three cable connectors,
Remove bottom plate by disconnecting four screws (Figure 6-20).
Remove ground wire screw under paper chute (Figure 6-21).
Cut tie wraps attaching wires to bottom plate (Figure 6-21).
10.

Pop carriage cable out of clips to free it from bottom plate (Figure 6-21).
NOTE

For reinstallation, twist the carriage cable connector

two turns counterclockwise before installation. This
prevents the cable from dragging and possible damage.

11.

Remove four screws, two clamps with two screws each (Figures 6-19 and 6-21), to free wires
from bottom plate. Note and mark the position of the clamps before they are removed.
Installation of these clamps is critical for proper mechanical clearance.

12.

Push all wires through top and out of way so they do not interfere with subsequent steps.

13.

Move carriage assembly to right side of carriage drive motor; that is, to position shown in

14.

Place Torx driver on carriage pulley hold-down screw (Figure 6-22 and 6-23).

15.

Loosen but do not remove the cable tension screws (Figure 6-21). It is recommended that no

16.

Remove hold-down screw from carriage pulley. Catch the washer between carriage assembly

Figure 6-22.

more than two or three turns be made when loosening these screws.
and the pulley (protruding side sets under pulley).

6-38

17.

Slide carriage to the left gently so the pulley does not disengage from cable wire (Figure 624) and that thereis no evidence of drag.
NOTE
If pulley disengages cable wire, it is difficult to restring and the unit may have to be returned to the manufacturer for service and repair.

18.

Loosen, but do not remove, eight rail hold-down screws to loosen four rail clamps (Figure 6-

25).
19.

Move the two rubber bumpers toward the middle of the slide rail (approximately 6 inches to

the right as viewedin Figure 6-25).
20.

‘Shde bottom rail to the left to disengage it from carriage assembly (Flgures 6-26 and 6-27).
Remove rubber bushing.

21.

Hold carriage steady (Figure 6-28) and slide top rail to left.

22,

Disengage top rail from carriage assembly, then remove carriage assembly from printer
(Flgure 6-29).

NOTE

After installing rails, retighten cable tension screws
loosened in step 15.
PRINTWHEEL

TRANSDUCER

AMP (H)

PCB (G)

REAR PCBs

SIGNAL CABLE
RECEPTACLE

SERVO PCB (C}

8044-16

Figure 6-16

Printer Showing Cover and Signal Cable Removed

6-39

REAR PCBs

REMOVED

8044-18

RUBBER FEET

Figure 6-17

Printer Tilted on Back

6-40

8044-17

BOTTOM PANEL REMOVED

Figure 6-18

Printer Showing Bottom Panel Removed

6-41

NYLON BLACK SCREWS

BOTTOM PLATE ATTACHING

CABLE CONNECTOR AND FASTONS

TIE WRAPS

8044-1

HARDWARE

Figure 6-19

Bottom View Showing Connectors, Cables, Tie
Wraps, and Attaching Hardware

6-42

BOTTOM PLATE

8044-15

Figure 6-20

Bottom View Showing Connectors Remove

CARRIAGE CABLE

BOTTOM PLATE
REMOVED

TIE WRAPS

CABLE
TENSION

SCREW

NYLON BLACK SCREWS

SCREW DRIVER INSERTED TO
REMOVE GROUND WIRE SCREW

8044-13

Bottom View Showing Bottom Plate Removed

Figure 6-21

o
6-44

TORX DRIVER INSERTED TO ACCESS
CARRIAGE PULLEY HOLD DOWN SCREW

8044-4

Figure 6-22 Bottom View Showing Carriage Assembly
Positioned for Carriage Assembly Pulley Access

-45

BOTTOM CARRIAGE ASSY PULLEY

HOLD DOWN SCREW

Figure 6-23

View Showing Pulley Hold-Down Screw

6-46

PULLEY WITH HOLD

DOWN SCREW REMOVED

CABLE WIRE

8044-6

Figure 6-24 View Showing Carriage Assembly Bottom
Pulley with Hold-Down Screw Removed

6-47

8044-7

SLIDE RAIL
HOLD DOWN SCREWS

Figure 6-25

View Showing Slide Rail Hold-Down S Créws

-4

-1