Integra CROMA24 User Manual
®
CROMA24
COLOR PRINTER
SERVICE MANUAL
This Page Intentionally Left Blank
®
Croma24™
COLOR INKJET
PRINTER
SERVICE MANUAL
Part Number 208817
Croma24 Service Manual
Copyright © 1995 and 1996 ENCAD®, Inc. All rights
reserved.
ENCAD is a registered trademark of ENCAD, Inc.
CROMA24™ is a trademark of ENCAD, Inc.
Other trademarks and registered trademarks are the
property of their respective owners.
No part of this manual may be copied or distributed,
transmitted, transcribed, stored in a retrieval system, or
translated in any human or computing language, in any
form or by any means, electronic, mechanical, magnetic or otherwise, or disclosed to a third party without
the express written permission of ENCAD, Inc., 6059
Cornerstone Court West, San Diego, CA 92121, U.S.A.
Printing history
1st Edition Rev A May 1997
4
FCC Statement (U.S.A.)
The United States Federal Communications Commision has specified
that the following notice be brought to the attention of the users of the
Croma24 printers.
FEDERAL COMMUNICATIONS COMMISION RADIO AND TELEVISION INTERFERENCE FOR CLASS B DEVICE
This equipment has been tested and found to comply with the limits for a
class B digital device, pursuant to part 15 of the FCC Rules. These
limits are designed to provide reasonable protection against harmful
interference in a residential installation. This equipment generates,
uses, and can radiate radio frequency energy and, if not installed and
used in accordance with the instructions, may cause harmful interference to radio communications.
User Instructions:
If the equipment does cause harmful interference to radio or television
reception, which can be determined by turning the equipment off and on,
the user is encouraged to try to correct the interference by one of the
following measures:
Croma24 Service Manual
• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and receiver.
• Connect the equipment into an outlet on a circuit different from
that to which the receiver is connected.
• Consult the dealer or an experienced radio/TV technician for
help.
Changes or modifications not expressly approved by ENCAD, Inc. could
void the user’s authority to operate the equipment.
5
Croma24 Service Manual
VDE Statement
Hiermit wird bescheinigt, daß der
den Bestimmungen der BMPT-AmstbIVfg 234/1991 funkentstört ist. Der
vorschriftsmäßige Betrieb mancher Geräte (z.B. Meßsender) kann
allerdings gewissen Einschränkungen unterliegen. Beachten Sie
deshalb die Hinweise in der Bedienungsanleitung.
Dem Zentralamt für Zulassungen im Fernmeldewesen würde dan
Inverkehrbringen dieses Gerätes angezeigt und die Berechtigung zur
Überprüfung der Serie auf die Einhaltung der Bestimmungen
eingeräumt.
ENCAD, Inc.
U.S.A
CROMA24
in Übereinstimmung mit
6
Material Safety Data Sheet
Croma24 Service Manual
CROMA24
no special disposal handling. It can be harmful if swallowed and should
be kept away from children.
To obtain a Material Safety Data Sheet, contact
International users should contact their local dealer or distributor.
QIS (Quality Image Supplies) ink is nonhazardous, requiring
ENCAD, Inc.
6059 Cornerstone Court West
San Diego, CA 92121-3734
(619) 452-4350
at:
7
Croma24 Service Manual
WARRANTY OR DAMAGE CLAIMS
United States
ENCAD®, Inc., warrants its printers ("PRODUCT") to be free from defects in workmanship
and materials for a period of one year from the date of purchase. In order to submit a
Warranty claim, please contact the ENCAD Help Desk at (619) 452-4350.
ENCAD reserves the right to make changes or improvements to Products, without
incurring any obligation to similarly alter Products previously purchased.
Buyer's sole and exclusive rights pursuant to this Warranty shall be for the repair or
replacement of defective Product. ENCAD specifically disclaims any and all other
warranties, expressed or implied, including but not limited to, implied warranties of
merchantability and fitness for a particular purpose. In no event shall ENCAD be liable
for any loss of profit or other commercial damages, special, incidental or consequential
damages, or any other damages or claims, whatsoever.
This Warranty gives Buyer specific legal rights, and Buyer may also have other rights
that vary from state to state.
This Warranty applies only to printers purchased from ENCAD, or authorized ENCAD
distributors or dealers. The intent of this Warranty is to repair or replace defective
Products subjected to normal wear and tear, when operated according to ENCAD
instructions.
This Warranty does not cover damage to the Product resulting from the following:
• Accident or negligence.
• Unauthorized modification of the Product.
• Adverse environmental conditions.
• Service of the Product by other than an ENCAD authorized service provider.
• Unauthorized or improper use, including but not limited to:
– Use in applications for which the Product was not designed.
– Using cartridges or ink other than those supplied by ENCAD or authorized
ENCAD resellers.
– Using media other than that supplied by ENCAD or authorized ENCAD
resellers.
– Lubricating any part of the printer.
Internationally: Contact your dealer or distributor for warranty information.
8
Croma24 Service Manual
Table of Contents
Chapter 1 General Description............................................................. 17
Introduction ...............................................................................................................17
Overview ...................................................................................................................18
Related Publications ...........................................................................................18
Electrostatic Discharge (ESD) Sensitivity ..................................................................18
Warnings, Cautions, and Notes.................................................................................19
Printer Specifications ................................................................................................20
Contents of this Service Manual................................................................................21
Technical Support .....................................................................................................2 3
Chapter 2 Theory of Operation............................................................. 25
Introduction ...............................................................................................................25
Croma24 Printer General Block Diagram ..................................................................25
Paper (Media) Axis Drive ..........................................................................................27
The Carrier Axis Drive...............................................................................................28
Main Printed Circuit Board (MPCB)...........................................................................29
Microprocessor ...................................................................................................3 0
Gate Array ..........................................................................................................3 0
Memory Circuits..................................................................................................31
Stepper Motor Controller.....................................................................................33
Servo Motor Controller........................................................................................34
Interface Circuits: Serial & Parallel......................................................................36
Carrier Assembly Circuits..........................................................................................37
Power Supply............................................................................................................38
System Grounding ....................................................................................................38
Front Key Controls ....................................................................................................40
Chapter 3 Maintenance ......................................................................... 43
Introduction ...............................................................................................................43
Scheduled Maintenance............................................................................................43
Cleaning Procedures ..........................................................................................44
External Cleaning .........................................................................................44
Slide Shaft Cleaning.....................................................................................44
9
Croma24 Service Manual
Table of Contents (cont)
Chapter 3 Maintenance (cont)
Service Station Cleaning ..............................................................................45
Linear Encoder Strip Cleaning......................................................................46
Cartridge Dimple Cleaning ...........................................................................47
Flex Cable Contact Cleaning........................................................................48
Clean and Inspect Stepper Motor Gears ......................................................48
Clean and Inspect MPCB .............................................................................49
Clean and Inspect Carrier Assembly ............................................................49
Reseat Connectors on MPCB and Carrier Board................................................50
Replace Carrier Bushings...................................................................................52
Servo Motor Winding Resistance Check...................................................................52
Stepper Motor Winding Resistance Check................................................................53
Banding: Hardware vs Software................................................................................53
Alignments/Adjustments............................................................................................55
Color Calibration .................................................................................................55
Deadband Alignment ..........................................................................................56
X-Axis Calibration ...............................................................................................57
Pinch Roller Adjustment Procedure ....................................................................57
Head Height Alignment Procedure......................................................................60
Croma24 Control Panel.............................................................................................65
Manufacturing Menu ...........................................................................................66
Print Quality T est..........................................................................................67
Deadband.....................................................................................................67
Diagnostics Menu ...............................................................................................68
Paper Sensor Test........................................................................................69
Fan Test .......................................................................................................69
Carriage Vibration Test.................................................................................70
Color Test .....................................................................................................70
Keypad Test .................................................................................................71
LED Test ......................................................................................................72
Servo Motor Test ..........................................................................................72
Paper Motor Test..........................................................................................73
Service Menu......................................................................................................74
Built In Test (BIT) ......................................................................................................75
10
Croma24 Service Manual
Table of Contents (cont)
Chapter 3 Maintenance (cont)
Firmware/Software Upgrades....................................................................................76
Internal Cabling and Signal Flow Diagram ................................................................77
Chapter 4 Troubleshooting................................................................... 79
Introduction ...............................................................................................................79
No Power ..................................................................................................................79
Media Does Not Move...............................................................................................80
Carrier Axis Failure ...................................................................................................81
Does Not Print...........................................................................................................82
Ink Cartridge Misfiring ...............................................................................................82
Paper Skewing ..........................................................................................................83
Printer Output is Banding ..........................................................................................84
Fan Does Not Power Up ...........................................................................................85
Chapter 5 Assembly\Disassembly ....................................................... 87
Introduction ...............................................................................................................87
Remove the Left, Middle (Lid), and Right Covers......................................................88
Install the Left, Middle, and Right Covers ..................................................................89
Remove the MPCB (Main Printed Circuit Board) and Actuator Assembly .................90
Install the MPCB and Actuator Assembly ..................................................................91
Remove Servo Motor ................................................................................................92
Install Servo Motor ....................................................................................................94
Remove the Carrier Assembly, Carrier Belt, and the Frame T ensioner .....................95
Install the Carrier Assembly, Carrier Belt, and the Frame Tensioner ........................98
Remove the Carrier PCB ........................................................................................100
Install the Carrier PCB ............................................................................................102
Remove the Paper Sensor or the Encoder Sensor .................................................102
Install the Paper Sensor or the Encoder Sensor .....................................................104
Remove the Trailing Cable Cover Assembly ...........................................................105
Install the Trailing Cable Cover Assembly ...............................................................107
Replacing the Carrier Bushings...............................................................................108
Remove the Service Station, Seals, and Wipers..................................................... 110
Install the Service Station, Seals, and Wipers ......................................................... 1 11
11
Croma24 Service Manual
Table of Contents (cont)
Chapter 5 Assembly\Disassembly (cont)
Remove the Lower Roller Assembly and Stepper Motor ......................................... 112
Install the Lower Roller Assembly and Stepper Motor ............................................. 115
Remove the Power Supply and AC Entry Module ...................................................117
Install the Power Supply and AC Entry Module .......................................................120
Chapter 6 Parts List ............................................................................ 123
Index..................................................................................................... 131
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Croma24 Service Manual
List of Illustrations
Figure Page
Chapter 1 General Description
Chapter 2 Theory of Operation
2-1. General Block Diagram ...................................................................................26
2-2. Paper (Media) Axis Drive.................................................................................27
2-3. Carrier Axis Drive ............................................................................................28
2-4. Main Printed Circuit Board...............................................................................29
2-5. Gate Array.......................................................................................................30
2-6. Stepper Motor Controller .................................................................................33
2-7. Servo Motor Controller ....................................................................................34
2-8. Quadrature Signal Generation.........................................................................35
2-9. Interface Circuits .............................................................................................36
2-10. Carrier Assembly Circuits ................................................................................37
2-11. Croma24 System Ground Network (Left Side) ................................................39
2-12. Croma24 System Ground Network (Right Side) ..............................................40
2-13. Front Key Controls...........................................................................................40
Chapter 3 Maintenance
3-1. Encoder Strip Cleaning....................................................................................46
3-2. Cartridge Dimple Region .................................................................................47
3-3. Flex Cable Contacts ........................................................................................48
3-4. MPCB Connection Locations...........................................................................50
3-5. Carrier PCB Connection Locations ..................................................................51
3-6. Ribbon Connector Locking Mechanism ...........................................................51
3-7. Servo Motor.....................................................................................................52
3-8. Stepper Motor..................................................................................................53
3-9. Examples of Banding ......................................................................................54
3-10. Color Calibration ..............................................................................................55
3-1 1. Deadband Fast/Slow .......................................................................................56
3-12. Upper Roller Support Description ....................................................................57
3-13. Upper Roller Mounting.....................................................................................59
3-14. Gap of Pinch Roller .........................................................................................59
3-15. Upper Roller Adjustment .................................................................................60
3-16. Carrier Head Height Tolerance........................................................................61
13
Croma24 Service Manual
List of Illustrations (cont)
Figure Page
Chapter 3 Maintenance (cont)
3-17. Setting Up Tools from Height Gauge Kit..........................................................61
3-18. Zeroing the Micrometer Gauge........................................................................62
3-19. Test Cartridge Installed....................................................................................62
3-20. Carrier Positions for Head Height Adjustment .................................................63
3-21. Maintenance Menu ..........................................................................................66
3-22. Manufacturing Menu........................................................................................66
3-23. Deadband Options Menu.................................................................................67
3-24. Deadband Slow/Fast Display...........................................................................68
3-25. Diagnostics Menu ............................................................................................68
3-26. Paper Sensor Reported Data Dialog Box ........................................................69
3-27. Fan Test Menu Panels.....................................................................................69
3-28. Color Test........................................................................................................70
3-29. Keypad T est.....................................................................................................71
3-30. LED Test..........................................................................................................72
3-31. Servo Motor Test.............................................................................................72
3-32. Paper Motor Test.............................................................................................73
3-33. Service Menu ..................................................................................................74
3-34. ROM Info .........................................................................................................74
3-35. Service Special Information .............................................................................75
3-36. Signal Wiring Diagram.....................................................................................78
Chapter 4 Troubleshooting
Chapter 5 Assembly/Disassembly
5-1. Cover Removal/Installation..............................................................................89
5-2. Frame Tensioner .............................................................................................92
5-3. Electronics Cover Removal .............................................................................95
5-4. Strain Relief Removal/Installation from Carrier................................................96
5-5. Carrier Belt Clamp...........................................................................................97
5-6. Installation of Frame Tensioner .......................................................................99
5-7. Carrier PCB Removal/Installation ..................................................................101
5-8. Paper and Encoder Sensor Removal ............................................................103
5-9. Paper and Encoder Sensor Installation .........................................................104
14
Croma24 Service Manual
List of Illustrations (cont)
Figure Page
Chapter 5 Assembly/Disassembly (cont)
5-10. Trailing Cable Assembly Removal/Installation ...............................................106
5-11. Carrier Bushing Removal ..............................................................................108
5-12. Carrier Bushing Installation............................................................................109
5-13. Service Station, Exploded View .....................................................................110
5-14. C-Bracket Assembly and Platen Removal ..................................................... 113
5-15. Stepper Motor Removal/Installation............................................................... 114
5-16. Installing Lower Roller Assembly ...................................................................116
5-17. Ground Stud with Ground Lugs Attached ......................................................118
5-18. Power Supply Assembly ................................................................................119
Chapter 6 Parts List
6-1. Croma24 Assembly Parts (Platen and Above)...............................................125
6-2. Croma24 Assembly Parts (Below Platen)......................................................126
6-3. Carrier Assembly Breakdown ........................................................................127
6-4. C-Bracket Assembly Breakdown ...................................................................128
6-5. Lower Roller Assembly Breakdown ...............................................................129
15
Croma24 Service Manual
List of Tables
Table Page
Chapter 1 General Description
Chapter 2 Theory of Operation
2-1. Front Key Control LED Codes .........................................................................41
Chapter 3 Maintenance
3-1. Pinch Roller Adjustments ................................................................................58
3-2. Keypad Test Indications...................................................................................71
Chapter 4 Troubleshooting
4-1. Troubleshooting Table .....................................................................................79
Chapter 5 Assembly/Disassembly
Chapter 6 Parts List
6-1. Parts List .......................................................................................................123
16
General Description
Introduction
This manual provides service information for the ENCAD, Inc.
Croma24 Color Inkjet Printer.
There are three versions to the Croma24 Color Inkjet Printer
family:
CAD version GA & CAD version GA version
for: CAD market GA & CAD GA
I/O: parallel serial & parallel serial & parallel
includes: ENCAD software RIP
All versions will have an ADI Windows driver and print utility.
This manual is written for service personnel who possess analog
and digital circuitry experience. Chapter 2, Theory of Operation,
should be read and thoroughly understood before troubleshooting/
calibrating the printers.
The printers support pre-cut and roll media. Media size is automatically determined and hardclip limits are set accordingly. Precut media uses different maximum plotting areas than roll media.
See the Printer Specifications for more details.
1
DESCRIPTION
GENERAL
Both RS-422 serial and Centronics parallel connections are provided to interface with the host computer on the GA (Graphic Arts)
compatable versions. Only the Centronics parallel connection
exists on the CAD only version. Commands sent from the host
computer are in Encad RTL format.
Drivers are supplied to support Windows-based PC’s (3.XX, 95, and
NT) as well as Macintosh and Power PC computers.
These printers expand upon ENCAD’s tradition of delivering fast,
high-quality color or monochrome graphics for a variety of applications. ENCAD has made significant advances in designing these
17
Croma24 Service Manual
plotters to respond to and anticipate our customers’ needs. Principal
features are summarized below.
Three Versions: CAD, GA (Graphic Arts), GA & CAD
ENCAD’s software RIP supplied with the GA (Graphic Arts) version
Remotely Configured via Host Computer
25" (63.6 cm) Maximum Media Width
600 x 600 dpi (mono) addressable
300 x 300 dpi (color)
Overview
Printers draw according to instructions issued from a “host” computer. Every printer is engineered to understand a specific set of
instructions and to execute each instruction in a precise manner.
In addition, most printers are designed to execute predetermined
characters automatically without a specific line-by-line instruction
from the program. These characters are part of the printer’s
permanent memory.
Related Publications
The following publication contains additional information which may
be useful in servicing the ENCAD, Inc. Croma24 Color Inkjet
Printers:
• ENCAD, Inc. Croma24 User Guide, P/N 207103
Copies of this and other ENCAD, Inc. publications may be obtained
by contacting your nearest authorized ENCAD, Inc. dealer or by
contacting ENCAD’s Technical Support and Service Department.
Electrostatic Discharge (ESD) Sensitivity
All PCBs (Printed Circuit Boards) associated with the Croma24
printers have components sensitive to ESD (electrostatic discharge). Care must be taken to avoid damage to any of the components by following current ESD handling procedures and practices.
Always use an approved ESD grounding strap when handling or
working with PCBs.
18 General Description
Croma24 Service Manual
W arnings, Cautions, and Notes
Warnings, cautions, and notes are used when additional information, instructions, or care should be observed. In this manual,
warnings cautions, and notes precede the text to which each applies. The definition of each is provided below.
WARNINGS - Warnings are used to stress that the following steps
or procedure has the potential to cause serious harm or death to
service personnel. Extreme care should be observed when following
the procedures and to exercise standard safety procedures. They
are indicated by:
Followed by a paragraph describing the concern.
CAUTION - Cautions depict that the following steps or procedures
can cause damage to the equipment if not properly followed. Extreme care should be observed when following the procedures and
to exercise standard safety procedures. They are indicated by:
DESCRIPTION
GENERAL
Followed by a paragraph describing the concern.
NOTE - Notes are placed before a procedure to inform the service
personnel of specific details to improve quality, to give reminders of
interrelated parts, and to provide other helpful information. They
are indicated by:
NOTE
Followed by a paragraph describing the concern.
General Description 19
Croma24 Service Manual
Printer Specifications
The specifications and performance characteristics of the Croma24
Color Inkjet Printers are as follows:
Max Printing Area:
Norm 23.8” 60.9cm
Extend 24.6” 62.9cm
Language Emulation:
ENCAD RTL
Buffer:
2 MB permanently
installed
(not upgradable)
Power Requirements:
Input Voltage:
90 - 246 VAC
47 - 63 Hz
Output Power:
24 W typical
63 W maximum
Baud Rates:
38400
1MByte High Speed
Serial (MAC only)
Resolution:
Mono 600x600 dpi
addressable
Color 300x300 dpi
Accuracy:
0.2% line length (with
ROLL mode off)
Interface:
Centronics parallel
RS-422 serial
(GA and GA/CAD
versions only)
Environment:
Operating:
41° to 104° F
(5° to 40° C)
10% to 70% RH
non-condensing
Storage:
-40° to 140° F
(-40° to 60° C)
5% to 80% RH
non-condensing
Dimensions:
Height 12” (305mm)
Width 43.5” (1105mm)
Dept h 14” (356mm)
20 General Description
Croma24 Service Manual
Contents of this Service Manual
Figures are used in this manual to clarify procedures. They are
for illustrative purposes only and may not necessarily be drawn to
scale.
Material in this manual may be repeated in various sections so
that each section can “stand alone”. This allows information to be
located without having to refer back and forth between sections.
Figures and tables are easily located and cross-referenced, and are
listed in the front of the manual under List of Illustrations and
List of Tables.
This manual is divided into six chapters as:
Chapter 1 GENERAL DESCRIPTION - Contains a general
description of the ENCAD Croma24 printer. This
includes printer specifications, and related materials.
Also included is a description of the use of Warnings,
Cautions and Notes as used in this manual and chapter
contents.
Chapter 2 THEORY OF OPERATION - Functional
descriptions of the overall printer and major assemblies
are contained in this chapter.
DESCRIPTION
GENERAL
Chapter 3 MAINTENANCE - This chapter covers the
scheduled maintenance, cleaning procedures and
alignment/adjustments recommended to perform on the
printers. Diagnostics and a signal flow diagram are also
listed.
General Description 21
Croma24 Service Manual
ORIENTATION - Instructions in this manual are based on the
assumption that the service person is facing the front of the
printer. References to top view, back view, and so forth are consistent with this engineering standard. References to the X Axis and
Y Axis (Paper Axis and Carrier Axis, respectively) follow the standard of AutoCAD™ absolute coordinates: up and down for X, left
to right for Y.
Chapter 4 TROUBLESHOOTING - A table containing
problems that could occur and possible causes and repairs
is found in this chapter. This table is not intended to be a
complete listing of troubleshooting procedures. It will
isolate the problem down to the lowest replacable
assembly. If the problem happens to be the wiring
between assemblies, standard troubleshooting techniques
will have to be implemented to correct the problem.
Chapter 5 ASSEMBLY/DISASSEMBLY - Contains detailed
procedures to remove and replace printer parts and
assemblies.
Chapter 6 PARTS LIST - Contains a complete listing of all
field replacable parts and assemblies for the Croma24
Color Inkjet Printer. Illustrated parts breakdown
drawings are included to help clarify and identify parts for
ordering. Special kits and adjustment jigs may be
required.
22 General Description
Croma24 Service Manual
T echnical Suppor t
ENCAD offers full technical support and service for its various
products. If you are unable to find the answer to your question in
either the User’s Guide, Service Manual, or other related publications, check out ENCAD’s Technical Bulletins located on
ENCAD’s bulletin board or the Internet:
ENCAD BBS: (619) 452-2653 or
ENCAD Website: http://www.encad.com
Additional information is available though our Technical Support
and Service Department’s Help Desk.
ENCAD, Inc.
Technical Support & Service Dept.
6059 Cornerstone Court West
San Diego, CA 92121
Help Desk Telephone: (619) 452-4350
Help Desk FAX: (619) 546-0659
DESCRIPTION
GENERAL
(619) 452-3768
International Users contact your local ENCAD service provider.
see details on your ENCAD registration card.
General Description 23
Croma24 Service Manual
This Page Intentionally Left Blank
24 General Description
Theory of Operation
Introduction
This chapter explains the mechanical and electrical theory of operation of the ENCAD Croma24 D-Size Color Inkjet printer.
The Croma24 is a MC68322 microprocessor-based digital printer
that receives plotting instructions from a host computer through
either the RS-422 serial interface or the Centronics parallel interface.
Croma24 Printer General Block Diagram
Figure 2-1 illustrates the major functional areas of the printer.
The Croma24 printer consists of two mechanical drives:
1. Paper (Media) Axis Drive
2. Carrier Axis Drive
2
THEORY OF
OPERATION
and three main electrical assemblies:
1. MPCB (Main Printed Circuit Board)
2. Carrier Assembly
3. Power Supply
25
Croma24 Service Manual
Figure 2-1. General Block Diagram.
26 Theory of Operation
Paper (Media) Axis Drive
Figure 2-2. Paper (Media) Axis Drive.
The Paper (Media) Axis Drive moves the plotting media in a direction perpendicular to the length of the printer. This friction drive
utilizes a micro-step drive technology and consists of a stepper
motor, reduction gears, lower drive shaft assembly, and pinch
wheels. This can be seen in Figure 2-2.
Croma24 Service Manual
THEORY OF
OPERATION
The micro-step technology associated with the stepper motor gives
the capability of a resolution up to 600 dpi.
The reduction gear meshes the stepper motor to the lower drive
shaft assembly which allows the media to advance or retract.
The purpose of the pinch wheels is to apply pressure to the media
onto the drive shaft assembly to reduce the chance of slipping.
Misaligned pinch wheels is the main cause of skewing of the media.
Theory of Operation 27
Croma24 Service Manual
The Carrier Axis Drive
Figure 2-3. Carrier Axis Drive.
The Carrier Axis Drive moves the printer’s carrier assembly along
the length of the printer. The drive consists of a servo motor, linear
encoder strip, drive belt, and tension assembly. These items are
illustrated in Figure 2-3.
The servo motor, drive belt, and tension assembly are the components that actually drive the carrier assembly. The servo motor
drives the belt back and forth allowing the attached carrier assembly
to be repositioned as required. The tension assembly is spring
controlled and allows the proper amount of tension on the belt.
The linear optical encoder strip is used to obtain the printers accuracy along the axis of the printer. It is made with 150 parallel lines
per inch etched into it. By utilizing two optical encoder sensors that
are slightly off set from each other, and reading the leading and
trailing edges of the lines, a resolution of 600 dpi can be obtained.
The stepper and servo motors are controlled from the main printed
circuit assembly by the microprocessor.
28 Theory of Operation
Main Printed Circuit Board (MPCB)
Croma24 Service Manual
THEORY OF
OPERATION
Figure 2-4. Main Printed Circuit Board.
The Main Printed Circuit Board (MPCB) consists of six functional
areas:
1. Microprocessor (CPU)
2. Gate Array
3. Memory Circuits
4. Stepper Motor Controller
5. Servo Motor Controller
6. Interface Circuits: Serial & Parallel
Theory of Operation 29
Croma24 Service Manual
Microprocessor
The microprocessor (a Motorola MC68322) is the central processor
unit which supervises system functions, executes the printer firmware, manipulates data, and controls input/output data busses. It
has a built-in parallel port, a two channel DMA (Direct Memory
Access) controller, timer module, clock generator, and an on-board
chip select generator. One DMA channel supplies data to the gate
array for jet firing; the other DMA channel is used to receive data
through the serial port via the gate array, or the serial port when
using a high speed serial mode. One timer generates a servo interrupt every millisecond.
The microprocessor halves the 40MHz crystal reference (X1) signal
to create the 20MHz system clock that is used for timing of all
internal circuitry.
The chip select generator is programmed to generate chip selects at
the appropriate addresses, with the appropriate data size (byte,
word) and with the appropriate number of wait states.
Gate Array
30 Theory of Operation
Figure 2-5. Gate Array.
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