Centronics 705 User manual

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MODEL 705
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PRINTER
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37400745 REV C FEBRUARY 1982
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TECHNICAL MANUAL

THE INFORMATION CONTAINED HEREIN IS
PROPRIETARY AND IS NOT TO BE RELEASED
OR REPRODUCED WITHOUT WRITTEN PER-
MISSION OF CENTRONICS data computer corp.
SERVICING INFORMATION FOR YOUR PRINTER MAY BE
OBTAINED BY CALLING THE NUMBERS LISTED BELOW.
(ASK FOR FIELD ENGINEERING)
CEnTRDntcs·
data computer corporation
Hudson, New Hampshire 03051
Tel. [phone], TWX. [phone], TLX. 94-3404
Field Engineering Headquarters -[phone]
-Regional Sales Offices -
Eastern Region (Mass.):
Central Region (Texas):
Western Region (Calif.):
Tel. [phone], TWX. 710-348-0343
Tel. [phone], TWX. 910-890-4916
Tel. [phone], TWX. 910-595-1925
-Regional Field Engineering Offices -
Eastern Region (Mass.): Tel. [phone]
Central Region (Texas): Tel. [phone]
Western Region (Calif.): Tel. [phone]
Centronics Data Computer (Canada) Ltd.
Mississauga, Ontario
Tel.[phone], TWX. 610-492-4382
Centronics Data Computer (U.K.) Ltd.
London, England
Tel. [phone], TLX. 851-877801
Centronics Data Computer (France)
50 Rue Dombasle, 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
© Copyright 1980 Centronics Data Computer Corp.
Tel. [phone], TLX. 385-9349
Centronics (Italia) S.P.A.
Via Santa Valeria 5, 20123 Milan, Italy
Tel. 809-514
4/80 Rev. B
All rights reserved
Patents pending in U.S.A. and other countries
Printed in U.S.A.
Specifications subject to change without notice

MODEL 705
PRINTER
37400745 REV c FEBRUARY
1982
TECHNICAL MANUAL

TABLE OF CONTENTS
SECTION 1-GENERAL INFORMATION PAGE
1.1 SCOPE .................................................................. 1-1
1.2 GENERAL DESCRIPTION .................................................... 1-1
1.3 PHYSICAL DESCRIPTION .................................................... 1-1
1.4 PRINTER OPERATION ....................................................... 1-3
1.5 RELATED PUBLICATIONS ................................................... 1-5
1.6 ACCESSORIES ............................................................ 1-5
1.7 SPECIFICATIONS .......................................................... 1-6
SECTION 2-CUSTOMER SUPPLIED COMPONENTS
2.1 INTRODUCTION ........................................................... 2-1
2.2 FORMAT CONTROLLER .............................................. : ...... 2-2
2.3 COMMUNICATIONS RAM (C-RAM) FORMAT ..................................... 2-5
2.4 CHARACTER GENERATORS .................................................. 2-8
2.5 DATA TRANSFER AND TIMING ................................................ 2-9
2.6 LOADING DATA FOR PRINTOUTS ............................................. 2-12
SECTION 3-INSTALLATION AND OPERATION
3.1 INTRODUCTION ........................................................... 3-1
3.2 INSTALLATION ........................................................... 3-1
3.3 SET-UP PROCEDURE ..................................... · .................. 3-2
3.4 CONTROLS ............................................................... 3-2
3.5 OPERATING NOTES ........................................................ 3-4
3.6 PAPER SPECIFICATIONS .................................................... 3-4
3. 7 LOADING PAPER .......................................................... 3-5
3.8 RIBBON CASSETTE ........................................................ 3-7
3.9 OPERATOR MAINTENANCE .................................................. 3-8
3.10 OPERATING CHECKS ....................................................... 3-8
SECTION 4-THEORY OF OPERATION
4.1 INTRODUCTION ........................................................... 4-1
4.2 'FUNCTIONAL BLOCK DIAGRAM DESCRIPTION ................................... 4-1
SECTION 5-. MAINTENANCE
5.1 INTRODUCTION .......... : ................................................ 5-1
5.2 CENTRONICS NAMEPLATE .................................................. 5-1
5.3 RECOMMENDED PREVENTIVE MAINTENANCE (P.M.) .............................. 5-1
5.4 TROUBLESHOOTING GUIDE .................................................. 5-2
5.5 RECOMMENDED TOOLS ..................................................... 5-3
SECTION 6-ADJUSTMENTS
6.1 INTRODUCTION ........................................................... 6-1
6.2 CHARACTER PRINTING ADJUSTMENTS ........................................ 6-1
6.3 PAPER MOTION ADJUSTMENTS .............................................. 6-3
6.4 ELECTRICAL ADJUSTMENTS ................................................. 6-3
705 TM 0745-C

SECTION 7-REMOVAL/REPLACEMENT
7.1 INTRODUCTION.;, ..........•.. , ...........•..•.•.•.....•. , .•............. 7-1
7.2 COVER ASSEMBLIES ............•......•....•..•••.....•.•.......•........• 7-1
7.3 PRINT HEAD ASSEMBLY ......•.........•..•....•..•..•..•......•••......... 7-2
7 .4 RIBBON GUIDE ASSEMBLY ................••....•...•....•....••........•... 7-3
7.5 POWER DRIVER POARD ASSEMBLY ........•......•..........•.•..•.....•...... 7-3
7.6 TIMING FENCE ASSEMBLY .....•........•..•••...•....•..................... 7-3
7.7 VIDEO AMPLIFIER ASSEMBLY ...•.•.•..••.•.....•••..•.•......... : ....••..... 7-5
7 .8 . LIGHTWEIGHT CARRIAGE ASSEMBLY ........•.•..•.•......•....•..•.........•. 7-5
7.9 STEPPER MOTOR ASSEMBLY, CARRIAGE DRIVE •...•..•..•.•......•..••••........ 7-6
7.10 STEPPER MOTOR ASSEMBLY, PAPER DRIVE •..•••.••.••...• ~ .••...•............. 7-7
7.11 PLATEN ASSEMBLY ..........•...•...•••..•....•••.•.•.•••..•.•.......•.... 7-8
7 .12 TRACTOR DRIVE ASSEMBLY •.- .•...•...•.....•.••...•.........•.............. 7-9
7.13 PIN FEED TRACTORS, LEFT/RIGHT ............................................ 7-9
7.14 PRIMARY VOLTAGE ASSEMBLY ........•••.....••..........••...•........... 7·10
7 .15 CAPACITOR/RECTIFIER BRIDGE ASSEMBLIES ....•..••..••......•..••••........ 7-11
7.16 FAN ASSEMBLY ........................•.......•..•.• : ........•..•.•..•. 7-12
7.17 LOGIC BOARD ASSEMBLY ...... : .•...••.••...••••.••..•••.•.•......•.•..... 7-12
7.18 FUSES ..............• .- ..•....•...........•..•.•.•.••.•....•...•.•.•.... 7-13
7.19 RECOMMENDED SPARE PARTS LISTING ...•..••...••.••...•..•...••••......... 7-13
APPENDIX A-ELECTRICAL DRAWINGS
APPENDIX B-INSTALLATION DRAWINGS FOR 705 CUSTOMER·
SUPPLIED CONTROL PANEL AND FORMAT CONTROLLER
705 TM 0745-C
ii

SECTION 1
INTRODUCTION
1.1 SCOPE
This manual describes the Model 705 printer
manufactured by Centronics Data Computer Cor-
poration. This manual also identifies the
components that must be pesigned, built, and in-
stalled by the customer (customer-supplied com-
ponents); theory of operation, and maintenance
information for the Centronics-supplied elec-
tronics and printer mechanism.
1.2 GENERAL DESCRIPTION
The Model 705 printer consists of a print
mechanism and print control logic with micro-
processor control. The data input cable, in-
put/output logic (Format Control), which inter-
faces the input device to the print control logic,
and the control panel are designed, built, and in-
stalled by the customer (customer-supplied com-
ponent). The character generators, which contain
dot matrix character formation data and are used
in the print control logic, are also customer sup-
plied. Stepper motors are used to control bidirec-
tional print head and paper movement. Basically,
the printer is a single print head, 7x8 dot matrix,
132 column printer with aprint speed of up to 180
characters-per-second (cps). Maximum through-
put is achieved with abidirectional print head that
seeks the shortest path to the next line of data
while printing successive lines. With bidirec-
tional paper movement capability (only possible,
with rear feed), printing of subscripts, super-
scripts, overprinters, and graphics are also made
possible. An underlining capability is provided by
a ninth pin in the print head.
1.3 PHYSICAL DESCRIPTION
The printer is completely self-contained, in-
cluding the print mechanism with micro-
processor electronics and integral power sup-
plies. Space is provided for customer-supplied
electronics (format board and control panel). The
printer stand and/or forms receiving tray (not
shown) are optional. The forms receiving tray is
standard with printer stand option.
Figure 1-1 Model 705 Printer
705 TM 07 45-C
1-1

The printer covers include several plastic covers
and one sheet metal cover. The top cover, the two
side covers, and the front cover are plastic, and
the rear cover is sheet metal. The lowerpart ofthe
front cover has an opening for a customer-
supplied control panel.
The printer consists of three major units: the
print mechanism, the electronics, and the paper
handling mechanism. (See Figure 1-2)
1.3.1 PRINT MECHANISM-The print
mechanism consists of the carriage assembly,
drive mechanism, and print head. The drive con-
tains a stepper motor which drives a continuous
belt that transports the print head and carriage
assembly back and forth along the platen.
PRINTER STAND
(OPTIONAL) .
1.3.2 ELECTRONICS-Printer control is provided
by the electronics which contains the input
power transformer, de power supply, customer-
supplied format control logic (Format Controller),
print control logic (Print Controller), and power
driver board. The Format Controller interfaces
between the Print Controller and the customer-
supplied control panel and input device. The Print
Controller contains the microprocessor, firm-
ware, control logic, and regulated powersupplies.
The Format Controller isa piggyback installed on
the Print Controller. The Power Driver Board is
located in front of the printer behind the front
cover. It provides the drive signals for the print.
head solenoids and stepper motors. A Video
Amplifier Board attached to the carriage
assembly provides timing pulses for horizontal
character registration.
10330
TRACTOR
PAPER FEED
Figure 1-2 Major Assemblies
705 TM 0745-C
1-2

1.3.3 PAPER HANDLING MECHANISM-The
paper handling mechanism is a tractor feed unit
that can accommodate up to four part fanfold
forms 4 inches (10.2 cm) to 17.3 inches (43.9 cm)
wide with a 13.2-inch (33.5 cm) maximum print
width.
The printer can have rear or bottom paper feed
and can handle up to four-part forms at a slew
rate of 15 inches per second (ips).
NOTE --------..
When bottom feed is used, bidirectional paper feed is NOT
possible. Paper can only be moved upward and maintain
proper line registration.
The number of lines printed per inch (line density)
is dependent on the customer-supplied Format
Controller and Control Panel.
1.4 PRINTER OPERATION
Figure 1-3 is a basic block diagram of the printer,
and Figure 1·4 is a pictorial diagram illustrating
the particular printer components and how they
r-----,
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CONT:: -AND INDICATORS
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relate to the format control and print control logic
boards.
The printer uses a microprocessor to control
printer operations. Under program control, the
microprocessor, located on the main logic board
(Print Controller), controls the receiving ofparallel
data in a particular format from the customer-
supplied Format Controller. The microprocessor
then acts on the data received to initiate such
functions as an internal self-test and provide the
results to the Format Controller, process print-
able data and move paper. During the printing
operation, the microprocessor initiates move-
ment of the print head, carriage and paper, and
monitors feedback from the limit switches, video
system, and paper empty switch to effect proper
execution of these motion commands. It main-
tains a record of the print head position at all
times; provides printer status information to the
Format Controller; and performs other "house-
keeping" functions.
Basically, all printer functions can be grouped in·
to one of three categories: (1) character printing,
(2) paper motion, and (3) auxiliary functions.
10331
PRINT PRINT
CONTROLLER WRITE PULSES HEAD
-"'
PRINT
SOLENOID ~
HEAD
DRIVE
CONTROL
•FORMATTED
DATA 1/0
•PRINT
COMMAND CARRIAGE CARRIAGE
HEAD MOTION_.... DRIVE
STEPPER
eCARRIAGE
MOVEMENT CONTROL MOTOR
•PAPER
MOVEMENT
•CHARACTER
LINE FEED
GENERATOR
PAPER MOTION.
PAPER
(PAPER
(CLGTOMER
--
DRIVE
STEPPER
SUPPLIED)
CONTROL MOTOR)
L __ _ _
_J
2~
VIDEO 1. 2
l l
READY TO END OF
PAPER
VIDEO
SYSTEM &
PRINT PRINT EMPTY
TIMING
SWITCH SWITCH
SWITCH
FENCE
Figure 1-3 Basic Printer Block Diagram
705 TM 07 45-C
1-3

SUPPLIED BY CUSTOMER
I
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CONTftOL PANEL
I
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FORMAT PRINT
SUPPLIED BY CENTRONICS
CORCUOT BREAK<R.@
mTER~---~'-RANS-•O-RME<>iR '-,
&
~.,..~~
~C DIODE BRIDGES •
CONTROLLER t-A-DD_,R•,.....ss ._us-ti I CONTROLLER ~l~es
CONTROL
""~
LEFT MARGIN INDICATOR ~ ~
RIGHT MARGIN INDICATOR~ EOP
POWER
DRIVERS
• PRINT HEAD lo
~~--<!~ CARRIAGEASSEMBt.Y
---· ~
;=,,-~~'
" MOTOR
Figure 1-4 Printer Pictorial Diagram
1.4.1 CHARACTER PRINTING-In the printer,
characters are printed by selectively activating
eight print wires aligned in a vertical column in
the print head. A ninth wire, under direct micro-
processor control, provides the underlining
capability. As the head moves across the paper,
the appropriate print wires are momentarily ac-
tivated, driving them against the ribbon, paper,
and platen to form the specified dot pattern. The
characters are printed at 10 characters per inch.
The print commands to the print wires are
developed by customer-supplied read-only
memories (PROMs or ROMs). To extract print in-
formation, the microprocessor addresses a
PROM memory location for each column within a
character.
705 TM 07 45-C
1-4
As shown in Figure 1-5, the print head is attached
to the carriage assembly, which in turn is at-
tached to a rotating carriage drive belt. The car-
riage is driven in the forward direction or in the
reverse direction by the carriage stepper motor
which rotates the belt clockwise (forward direc-
tion) or counterclockwise (reverse direction).
1.4.2 PAPER MOTION-Paper can be moved
manually by pushing in and rotating the platen
knob, or electromechanically when paper move-
ment information is received from the customer-
supplied Format Controller. The information pro-
vided by the Format Controller establishes the
direction and amount of paper movement, which
can be from .00833 inch to 34.133 inches in
.00833-inch increments per paper .movement
operation.