Centronics 704 User manual

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4
AUG 1979
Centronics
No.
37400700
Rev-1
Ta Re mm Rad Seb Oo
Mee SOT me tte eee
TECHINIGAL
MANUAL
Pens ecient ee nF nee etn eee vat
CENTRONICS’
data computer corporation
Hudson, New Hampshire 03051
Telephone [phone]

THE INFORMATION CONTAINED HEREIN [S
PROPRIETARY AND !IS NOT TO BE RELEASED
OR REPRODUCED WITHOUT WRITTEN PER-
MISSION OF CENTRONICS data computer corp.
CENTRONICS
Centronics Data Computer Corp.
Hudson, N.H. 03051
Tel. [phone], TWX. [phone], TLX. 94-3404
Eastern Region (Mass.): Tel. [phone]
Central Region (Texas): Tel. [phone], TWX. 910-890-4916
Western Region (Calif.): Tel. [phone], TWX. 910-595-1925
Centronics Data Computer (Canada) Ltd.
Mississauga, Ontario
Tel. [phone], TWX. 610-492-4382
Centronics Data Computer (U.K.) Ltd.
London, England
Tel. [phone], TLX. 8951373
Centronics Data Computer (France)
50 Rue Dombasie, 75015 Paris, France
Tel. [phone], TLX. 202686
Centronics Data Computer (Germany), Gmbh
6000 Frankfurt am Main 71
Tel. [phone], TLX. 841-413224
Centronics of Puerto Rico
Dorado, Puerto Rico
Tel. [phone], TLX. 385-9349
copyright 197§$ Centronics Data Computer Corp.
All rights reserved
Patents pending in U.S.A. and other countries
Printed in U.S.A.
Specifications subject to change without notice.
In the U.S.A., for fast service call toll free 1-800-258-1952

TECHNICAL
MANUAL
MODEL 704 PRINTER
CENTRONICS’
data computer corporation
Hudson, New Hampshire 03051
Telephone [phone]

TABLE OF CONTENTS
SECTION 1
INTRODUCTION
Section
1.1 MANUALS. «© 2 2 «© «© «© «© «@
1.2 GENERAL DESCRIPTION. . +2 eo e
1.3 PHYSICAL DESCRIPTION . « o« -«
1.321 Print Mechanism . . .
12-342 Electronics. . «2. e e
123.3 Paper Handling Mechanism
1.4 PRINTER OPERATION - - + «© -
1-4-1 Character Printing - .
124.2 Paper Motion . .- « .e
1-4.3 Special Functions. e °
1.5 SPECIFICATIONS SUMMARY. . . .
SECTION 2
INSTALLATION/SET-UP
2e1 INTRODUCTION ~© «© © © e© oe .e
202 FLOOR PLANNING -«© «© «© oc e e
203 SET-UP PROCEDURES e e e e e
SECTION 3
THEORY OF OPERATION
3e1 OVERALL OPERATION . + ce o« -«
301.1 Input/Output Signals °
301.2 Microprocessor control .
321.3 Memory Organization. .
3.2 MICROPROCESSOR (MPU) . «© « «
3e2e1 Architecture e e e e ° e
3e2Qe2 Timing e e e e ® e e e
36223 Basic MPU Operation . . « .e
30204 Microprocessor Program Control
-j-
4=3
1-3
1-3
1-4
1-7
1-7
3-4
3-4
3-6
3-6
3-9

TABLE OF CONTENTS (cont'd)
Section
3.3
35
3.7
3.8
3.9
3.10
BUS STRUCTURE»~ «© « o «+ e
3.1 General Description .
32 Detailed Description
033 Input Data Transfers.
3.4 I/O Bus Transfers. .
SYSTEM TIMING \ e e ee e@
SERIAL COMMUNICATIONS « « e«
3-5-1 Input Data e ° ° ®
3.5.2 Output Datae e ° e
CONTROL CHARACTERS »« «.« co e
. Firmware Response .
3.6.1
36-2 Control Codese . .«
6
6
MRI AND DEVICE SELECT DECODING
367.1 Device Select . . .e
3e7e2 MRI Decoding e e e
CONTROL PANEL/MPU COMMUNICATIONS
VFU Reader/MPU COMMUNICATIONS
PRINTER MECHANISM OPERATION . e
3-10.1 Carriage Motor Operation
3210-2 VIDINT Generation e
3e-10.3 Character Generation.
MISCELLANEOUS OPERATIONS e
3-11.-1 Audio Alarm e ee e
3e11-2 Paper Out e e e e
3211-3 Motor Control « . .
STEPPER MOTOR OPERATION . .-
POWER DISTRIBUTION ~ -«© «© e
3-18
3-19
3-20
3-20
3-23
3-24
3-24
3-26
3-27
3-29
3-29
3-30
3-31
3-35
3-35
3-35
3-36
3-36
3<38
3-41

ATO ng SR Re MN: IE ree ne 9
TABLE OF CONTENTS (cont'd)
-1ii-
®
Section
SECTION
4
MAINTENANCE
4.1 INTRODUCTION ~ .« 6 «© © ee e« e
4.2 PRINTER MARKING AND CONFIGURATION .
4.2.1 Centronics Nameplate . .
4.262 Fuse Marking and Location .
4.2.3 logic Board Marking and Configuration
4.2.4 Dip Switch Settings, Control Panel .
4.3 RECOMMENDED PREVENTIVE MAINTENANCE.
4.4 TROUBLESHOOTING GUIDE ~ .«. 26 e« e
4.5 RECOMMENDED TOOLS .© +26 e« e« e oe.
SECTION 5
ADJUSTMENTS
5 e 1 INTRODUCTION e e e e ‘eo e e e
5.2 CHARACTER PRINTING ADJUSTMENTS ..
5.2.1 Penetration Adjustment, Print Head
522-2 Timing Fence Adjustment. .
522-3 Carriage Actuator Arms Adjustment
5.2.4 Main Drive Belt Adjustment.
5.3 PAPER MOTION ADJUSTMENTS ~ -« e« -«
5.3.1 Paper Feed Timing Belt Adjustment
523-2 Platen Adjustment. . . .
5-323 Tractor Drive Timing Belt Tension
5.3.4 Paper Tension Adjustment.
5.4 ELECTRICAL ADJUSTMENTS 2° e e«
5.4.1 Video Amplifier Adjustments
5.4.2 Logic Board Adjustments. .
SECTION 6
REMOVAL/ REPLACEMENT
6.1 INTRODUCTION ~ «© 5» © © «© e« «
6. 2 COVER ASSEMBLIES . e oe e e e e
6.3 PRINT HEAD ASSEMBLY. . . .. .
6.4 POWER DRIVER BOARD ASSEMBLY . . .
6.5 TIMING FENCE ASSEMBLY - 2. « o« .
6.6 VIDEO AMPLIFIER ASSEMBLY . . . .
4-1
4-2
4-2
4-9
4~11
4-13
5=1
5-2
5=3
5=3
5-4
5-4
5=5
5=5
5-6
5-6
5-6
5-9
6-4
6-5
6-6

TABLE OF CONTENTS (cont'd)
Section
6.7 RIBBON CARTRIDGE ASSEMBLY . 28 ee
6.8 LIGHTWEIGHT CARRIAGE ASSEMBLY . . .-
6.9 STEPPER MOTOR ASSEMBLY, CARRIAGE DRIVE
6.10 STEPPER MOTOR ASSEMBLY, PAPER DRIVE .
6.11 PLATEN ASSEMBLY © 28 © © e © 8
6.12 VERTICAL FORMAT UNIT ~© -© «© © » -»
6.13 TRACTOR DRIVE ASSEMBLY °° es e ee
6.14 PIN FEED TRACTORS, LEFT/RIGHT . . .
6.15 PRIMARY VOLTAGE ASSEMBLY . . . e« -
6.16 CAPACITOR/DIODE BRIDGE ASSEMBLY 2.
6.17 FAN ASSEMBLY * e «© e© © © «
6.18 LOGIC BOARD ASSEMBLY . .« .« « -« .e
6.19 CONTROL PANEL ASSEMBLY © ©e© © © e
SECTION 7
ELECTRICAL DRAWINGS
APPENDIX
SIGNAL GLOSSARY
6-10
6-11
6-12
6-13
6-14
6-14
6-16
6-17
6-18
6-19
6-20

2-2
3=1
3-3 ©
3=4
3-5
3-6
3-7
3=8
3-9
3-10
3-11
3-12
3-13
3-14
3-15
3-16
3-17
3-18
3-19
3-20
3-21
3-22
3-23
3-24
3-25
3-26
3-27
4-1
4=2
4=3
5-1
5=2
5=3
LIST OF ILLUSTRATIONS
Model 704 Printer. . . .« «© e« «6 «o « «
Major Assemblies ~- .« .« .« «.« « «ce e« e« -e
Printer Basic Block Diagram . . . .« « -
Printer Pictorial Diagram. . . . « « e
Character Printing/Paper Motion . . . .e« .e
Printer Outline Drawing. . . .« .« .« e« e
Set-Up Proc edur eS e e e e e e ° ® e e
Overall Block Diagram . . . . « «o« « .e
Memory Map - +« +« e« «© © e © © © « -«
8080A Microprocessor Pin Designations . . .
MPU Block Diagram. . .« +« «+ « «« « « e
Typical Output Instruction Cycle Timing . .
MPU Status Word . . +6 « «© © «© «© « e
Bus Structure Block Diagram . . .« .« « e
$1/82 MPU Timing Circuit © e © e « ef
G$2BY2/P2BY8 Timing Circuit . °° © e © e
Data Bus Assignments (Baud Rate Commands). .
Control Panel Status Word . . -« .« « « «
Exploded Section of Timing Fence. . . e« .«
Video Amplifier Simplified Schematic . . .
Video Edge Detector Circuit/Timing . . . .-
Miscellaneous Operations . e« «.« «+« « e« -.
Basic Stepping Motor Operation . .-« «+ «+ .e
Stepper Motor Drive Circuit ele le lls
Power Distribution Diagram. .« + «© «+ e e
~- FLOW CHARTS -
Printer Initialization .~. .« .« c« -« .« e «
Main Program Monitoring loop - -« + e« e e
Print Routine ~. . «.« «- e« © «e« «e« se e -«
Video Interrupt Routine. . .« e« « e e e
Carriage Drive Interrupt Routine. . . .« .
Paper Drive Interrupt Routine. .« . .« e« e
Control Character Interrupt Routine. . . .
VFU Paper Tape Load Routine . . .« .« e e
Control Character Interrupt Routine. . . .
Centronics Nameplate. . . +« e« .« e e« «
logic Board Marking «© -« +« e« « « e « e
Dip Switch Setting (Control Panel) - . -« .-
Recommended Tools © 8 © © © © «© e@ -@
Penetration Adjustment (Print Head Assembly).
Timing Fence Adjusttment . -« +« « oc « -e
Carriage Actuator Arms Adjustment -. + « -
==
2~1
2-3
3-0
3-2
3-4
3-5
3-7
3-8
3-10
3=17
3-18
3-19
3-27
3-30
3-31
3-32
3-36
3-38
3-39
3-41
3-42
3-43
3-44
3-45
3-46
3-47
3-48
3-49
3-49
4-1
4-2
4-3
4-13
5=2
52
5=3

oy Ongena a 8 Eo San cc amg
Figure
5-4
5=5
5-6
5-7
5-8
5-9
5-10
5-11
6-1
6-2
6-3
6-4
6=5
6-6
6-7
6-8
6-9
6-10
6-11
6-12
6-13
6-14
6-15
6-16
6-17
7=1
7-2
7=3
7-4
7=5
7-6
7=7
7-9
7-10
LIST OF ILLUSTRATIONS
Main Drive Belt Adjustment. . .
Paper Feed Timing Belt Adjustment
Platen Adjustment ©. © © © -»
Tractor Drive Timing Belt Tension
Paper Tension Adjustment . . «
Optical Pickup/Timing Fence Alignment
Optical Pickup, Vertical Alignment .
Duty Cycle and Phase Adjustment of Video
~ REMOVAL/ REPLACEMENT -
Cover Assemblies ~- .« .« .« e«
Print Head Assembly ~ . .« e« e-
Power Driver Board Assembly . .
Timing Fence Assembly . . .« «
Video Amplifier Assembly . . .
Ribbon Cartridge Assembly . . .
Carriage Assembly °° 8 e© «© e
Stepper Motor Assembly, Carriage Drive.
Stepper Motor Assembly, Paper Drive.
Platen Assembly . .-« .« .« o «
Vertical Format Unite . . e« .
Tractor Drive Assembly Pin Feed Tractors,
Primary Voltage Assembly .. .
Capacitor/Diode Bridge Assy . .
Fan Assembly .« -« « 6 e« e« «
Logic Board Assembly. . . « «
Control Panel Assembly . . . .
~- FUNCTIONAL SCHEMATICS =
Data/IO/Address BuS «© .« .« «= .«
Input Data ~ .« «© «© «© © ee «@
Device Select . .« « .« .o« « e
Control Panel/MPU. ° ° e e °
VFU Reader/MPU. e e e . e e
CG/STM/CRM/MPU. .« e« «© © e« e
- SCHEMATIC DIAGRAMS
Logic Board © 6 © © © « e
Power Driver Board .~ .« +e « .e
Video Amplifier Board . . . .-
Control Panel Board . . »« « .
e
o
5-4
5-4
5=5
5-5
5-6
5-7
5-7
5-9
6-0
6=3
6-4
6-5
6-6
6-7
6~9
6-10
6-11
6-12
6-13
6-15
6-16
6-17
6-18
6-19
6-20
7=3/7=4
7-5/7-6
7=7/7-8
7-9/7=10
7=11/7=12
7~13/7-14
7-18 _
7=19
72 1
7-22