Colortrac 3 Series User manual

SERVICE MANUAL
for
COLORTRAC LARGE FORMAT SCANNERS
models
380 Gx Plus, 360 Gx Plus and 340 Gx Plus
380 Cx and 360 Cx
Raising Lid Option

Colortrac Service Manual – Colortrac Series 3 Colour Document Scanners
2
Revision11.0
© Colortrac 1997
This document should not be copied without prior permission from:
Colortrac Ltd
Kings Hall
St. Ives Business Park
St. Ives
Huntingdon
Cambridgeshire
PE17 4WY
United Kingdom
Tel: [phone]
Fax: [phone]
Colortrac Ltd makes no warranty with respect to this documentation and disclaims any implied warranties of merchantability or fitness for a
particular purpose. Information in this document is subject to change without notice. Colortrac Ltd assumes no responsibility for errors that may
appear in this document.

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CONTENTS
1. INTRODUCTION 5
2. SAFETY REQUIREMENTS 6
3. SYSTEM DESCRIPTION 7
3.1 Scanning Principles 7
3.2 Adjustments Associated With Scanning 8
3.3 System Diagram 12
3.4 Camera boards 13
3.5 Digital Board 14
3.6 Display Board /Paper Sensor 16
3.7 Ballast System /light Sensors 16
3.8 Data Rates / Volumes (Doc 8) 16
4. ASSEMBLY DESCRIPTION 17
4.1 Replacing the Digital Board 18
4.2 Changing Cameras 18
4.3 Replace both fluorescent tubes 18
4.4 Replace the glass 18
4.5 Replace the paper holdown 18
4.6 Lubricate the reduction gear. 19
4.7 Set-up & Test Procedure for Raising Lid. 19
4.8 Glass Height. 20
5. PASSWORDS 21
6. CALIBRATION PROCEDURES 22
6.1 Focus Adjustment 22
6.2 4. Magnification Adjustment 24
6.3 String Adjustment 26
6.4 Stitch 30

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6.5 Light Level Adjustment 32
6.6 Motor Speed Adjustment 32
6.7 Calibration 32
6.8 Downloading Firmware 32
7. MAINTENANCE 33
8. FAULT FINDING 34
9. WARM UP AND CALIBRATION SEQUENCES 35
9.1 Warm up sequence 35
9.2 Calibration sequence 35
10. TOOL REQUIREMENTS 36
11. RECOMMENDED SPARES 37
12. SPARES LIST 38

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1. INTRODUCTION
This manual contains the information required to service and repair a Colortrac Series 3 colour
scanner. It does not cover specification, installation, operation or operators safety as these are
covered in the installation and operating manual.
There are five different variance of the series 3 scanner which are:
Scanner
Type Maximum Resolution Optical Resolution Mode No Of Cameras Scan Width
380Gx+ 800 400 RGB 3 100cm
360Gx+ 600 400 RGB 3 100cm
340Gx+ 400 400 RGB 3 100cm
380Cx 800 400 8 bit
Palette 3 100cm
360Cx 600 300 8bit
Palette 2 88.9cm
360Gx
junior 600 300 RGB 2 88.9cm
The service manual assumes that the scanner is a 380 GX plus is being serviced. The physical
difference between the the camera models is a hardware dongle on the digital board.
The effect of changing the number of cameras also has an impact on the cables to the cameras and
the camera lenses.

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2. SAFETY REQUIREMENTS
Electrical Safety warning.
Do not remove any of the cover panels without disconnecting the power. It is important not to
remove the two power supply boards until they have been left off for at least half an hour.

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3. SYSTEM DESCRIPTION
This section covers the basic principle behind the Colortrac scanners and the main electronic
components that carry out this operation.
3.1 Scanning Principles
The heart of the scanner is a Charged Coupled Device (CCD) which is an electronic component that
converts light into voltage. Each CCD has three rows of light sensitive cells which are focused onto
a line of the image that is being scanned. The image is then moved in order to build up a two
dimensional picture.
The construction of the CCD is shown below and show that each of the CCDs rows is sensitive to a
different colour light. The information can then be used to build up a colour image.
Each light sensitive cell is 8 um by 8 um and there is a separation of 8 pixels between each of the
colours. The total number of pixels in a row is 5363. Since the scan width of the 380 model is 1000
mm ( 39.375”) and the optical resolution is 400dpi, the number of pixel required is 15750.
Therefore in the 380 models, three CCDS are used to build up the image. The optical resolution in
the 360 model has been reduced to 300 dpi and therefore only two cameras are required
Red Green Blue
8 pixels 8 pixels
64 um 64um
5363 pixels
42.9mm
Paper Direction

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3.2 Adjustments Associated With Scanning
The Colortrac scanner produces a high quality scan which requires compensation for a number of
inherent problems. These adjustments are as follows:
Left / Right Stitch
Front / back Stitch
Magnification and Focus
Light and Dark Normalisation
Colour delay Compensation
The Left / Right Stitch and Front back stitch are adjusted both electronically and mechanically. The
magnification and focus are purely mechanical adjustment where as the Normalisation and colour
compensation is completely electronic.
The exact methods of carrying out these are described in the calibration section of this manual.
3.2.1 Left / Right Stitch
The scanner contains three cameras which are mounted along the line of scan. These three camera
have got to be adjusted to ensure that there is not a gap or overlap in a scan as illustrated in the
diagram below.
Scan Line
L/R Stitch
Mag
Focus
Camera 1 Camera 2 Camera 3
The adjustment is carried out in two ways. The camera are mechanically adjusted to ensure that
there is sufficient overlap between the cameras. The total number of pixels in a camera is 5363 but
only 5250 pixels are used. This allows us select electronically which pixels are used and therefore
effectively move the image electronically. This allows the image to be joined to within a pixel. The
“ 113” Pixels of adjustment represents 0.25” of adjustment.

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3.2.2 Front / Back Stitch
The front / back stitch is carried out in order to align the three camera along the line of scan. This is
initially carried by aligning each camera to a string that is stretch across the top of the scanner. This
adjustment is sufficiently accurate to ensure that the electronic adjustment can align the camera
within a line. For each electronic line of adjustment a complete scan line has to be store in memory.
This means that there is only sufficient memory to store fourteen scan lines which gives of 0.035”
adjustment. Therefore it is critical to set this adjustment up carefully.
3.2.3 Magnification / Focus
The resolution of the scan in the X direction is set up by the magnification. This is adjusted by
moving the CCD and Lens up or down. As the Lens and camera assembly are dropped the area that
is covered by a single CCD is increased which effectively reduces the magnification.
Obviously if the distance between the lens and the scan line is moved then the system will be out of
focus. The focus is adjusted by changing the distance between the CCD and the lens. This also
effects magnification.
The passage above described the how the magnification is set in the X direction, focus is set for
both the X and Y axis, however the magnification in the Y axis is set by motor speed. The faster the
motor goes the lower the resolution. The motor speed can be adjusted to compensate for any
variation in the systems. ( The MT8 test is used in the factory to calculate the motor speed)
3.2.4 Light Normalisation, Dark Normalisation and Brightness Adjust
Dark normalisation is an automatic process that takes in account variation in the CCD output when
there is no light falling on it.
The light Normalisation ensures that that for an even distribution of light across the scan line the
voltage produced by the CCD is constant. output. This is required because there are a number of
factors that effect the response of the CCDs. The light passes through a lens which effects the
distribution of light falling on the CCD. The CCD does not respond in a linear fashion across it
length. These two effects are illustrated in the diagrams bellow.

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Lens Intensity Fall Off
Intensity
100%
70%
Centre Xdisplacement
Raw CCD Data
Volts
Pixels