HP Indigo press 3050 User manual

HP Indigo press series 5000 and HP Indigo press series 3000
Troubleshooting Guide
Banding

HP Indigo Sheet-fed Presses
HP Indigo press 3050, HP Indigo press 3500,
HP Indigo press 5000 and HP Indigo press 5500
Troubleshooting Guide for
Customer Engineers
Banding

Copyright
© 2008 Copyright Hewlett-Packard
Development Company, L.P.
Reproduction, adaptation, or translation
without prior written permission is prohibited,
except as allowed under the copyright laws.
The information contained herein is subject
to change without notice.
The only warranties for HP products and
services are set forth in the express warranty
statements accompanying such products and
services. Nothing herein should be construed
as constituting an additional warranty. HP
shall not be liable for technical or editorial
errors or omissions contained herein.
HP, HP Indigo Press, HP Indigo Press RIP,
and HP ElectroInk are trademarks or
registered trademarks of HP.
All other products or name brands are
trademarks of their respective holders.
The HP Indigo press is a Class 1 Laser
Product containing high voltage power
supplies and laser light sources.
There is no danger to persons or equipment
when the system is operated in accordance
with the directions provided by HP in this and
other publications. All high voltage power
supplies and laser sources are located
behind protective covers. Warning labels are
attached to each protective cover. Do not
remove covers.
Confidentiality notice
This troubleshooting guide and any
information contained herein is confidential
and should not be disclosed to any third
party outside of HP Indigo. Do not copy
and/or disseminate any information
contained in this guide. This guide should
be maintained in a manner which shall
ensure compliance with the confidentiality
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This document contains valuable trade
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Hewlett-Packard Company. Nothing herein
may be copied, reproduced or distributed in
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whole or in part.
Part Number:
CA293-04200
First Edition:
July 2008

EN Contents 3
Contents
Preface ...................................................................................................................................4
General safety instructions.................................................................................................................. 4
About this troubleshooting guide......................................................................................................... 4
Documentation conventions used in this guide .................................................................................. 4
Introduction.............................................................................................................................5
What is banding .................................................................................................................................. 5
Troubleshooting Methodology............................................................................................................. 6
The banding troubleshooting overview ............................................................................................... 6
Banding troubleshooting road map ..................................................................................................... 7
Banding troubleshooting.........................................................................................................8
Pre-troubleshooting checklist.............................................................................................................. 8
Identifying the banding type ................................................................................................................ 9
Troubleshooting by banding type...................................................................................................... 10
Causes of Banding ...............................................................................................................12
(C) Consumables banding ................................................................................................................ 12
(E) Electrical banding........................................................................................................................ 12
(WH) Writing head banding............................................................................................................... 13
(LUT) Screening and machine LUT artifact banding ........................................................................ 13
(M) Mechanical interferences............................................................................................................ 14
Appendix 1 Banding Types - Samples................................................................................. 15
Constant - Single banding................................................................................................................. 15
Constant - Group banding................................................................................................................. 16
Random banding............................................................................................................................... 16
Periodic banding ............................................................................................................................... 17
Appendix 2 Gear Transmission Schemas ........................................................................... 18
Appendix 3 Periodic banding table – caused by gears and rotating parts........................... 19
Appendix 4 Constant banding table..................................................................................... 21
Appendix 5 Troubleshooting constant banding caused by gear teeth ................................. 22
Locating a defective or dirty tooth on the ITM drum gear or impression drum gear......................... 22
Locate the defective or dirty tooth on the PIP drum gear ................................................................. 22
Appendix 6 Second transfer banding - troubleshooting procedure......................................24
Appendix 7 Optional alternative mechanical banding diagnostic method............................25

4 Preface EN
Preface
Welcome to the HP Indigo Sheet-fed Presses banding troubleshooting guide for customer engineers. The
purpose of this guide is to assist customer engineers in:
•Understanding the causes of banding phenomena,
•Diagnosing banding issues, and
•Systematically applying recommended solutions.
This guide was initiated by members of the manufacturing print quality forum. Recommended solutions have
been collected from manufacturing and R&D engineers. Procedures applicable to the HP Indigo press 3050
are noted.
As this is the first edition of the guide, these recommended solutions may not be exhaustive and we look
forward to more input from the field. Please address feedback and comments to [e-mail].
General safety instructions
•HP Indigo presses must be operated and maintained only by properly trained personnel.
•All operating safety procedures listed in the online help and in the User Guide should be read and
understood.
•Customer engineers should not perform any actions on the press other than the procedures for which
they have been trained.
About this troubleshooting guide
•Troubleshooting diagnostic jobs must always be deleted from the client press before leaving the client
site.
•Follow the steps described for each possible solution. Some procedures are described in full, others
make reference to appendices at the end of the guide and some refer to other reference manuals.
•The guide assumes that the customer engineer has at least 6 months of experience on the HP Indigo
presses.
Documentation conventions used in this guide
•Keyboard keys to press appear in all capital letters, for example: Press the SHIFT key.
•Menu options are indicated in bold type, for example: On the File menu, click New.
•Menu path notation example: Perform the Adjustments > Suction Cup Margin Adjustment wizard.
•Window names appear in italics, for example: After selecting the options in the Print window, click
OK.
•References to other sections in the guide appear in quotes and bold, for example: See “Appendix 1
Banding Types - Samples” on page 15.

EN Introduction 5
Introduction
What is banding
•Banding appears as sets of lines across the width of
the page.
•Banding results from interference in the image
production process at sensitive stages:
•Image writing
•Image generation
•First transfer
•Second transfer
•Interference has two effects:
•Changes the rotation speed of the drums. This
interferes with the vertical placement of rows of
dots. When the drums:
•Slow down - several rows of dots are printed
closer together - dark banding.
•Speed up - several rows of dots are printed
further apart - lighter banding.
•Changes in pressure interferes with dot size:
•Too much pressure - dot smearing - dark banding.
•Too little pressure - dot shrinking - lighter banding.
Figure 1 Banding across page width
Figure 2 Image processing system
1
2
3
4
5
Leading edge
5 visible bands
Writing head
Laser beams
PIP drum sholder
Left scorotron
Cleaning station
ITM drum
Paper entering the
paper path
Impression drum
PIP drum gear teeth

6 EN
Troubleshooting Methodology
Perform the following steps:
1. Perform all the steps in the “Pre-troubleshooting checklist” on page 8.
2. “Identifying the banding type” see page 9.
3. Perform all the steps in the relevant troubleshooting topic - “Troubleshooting by banding type” on
page 10.
The banding troubleshooting overview
This is the summary of most of the banding diagnosis steps in this document. There are 3 sections:
Banding Type
Defines banding by its appearance on the print sample job. There are four major types:
Banding type Possible causes
Random banding Electronic, Electrical failures:
•Short circuits
•Faulty or unstable bias contacts
•Static charge breakthrough
•Faulty grounding, etc…
•Dynamic mirror / prism
malfunction
•Encoder malfunction
•Main drive / controller
malfunction
Constant banding •Local loads
•Faulty consumables
•Drum teeth issues
Periodic banding Gear transmission:
•Gear or pully
Rotating parts:
•BID unit
•Cleaning station
•Writing head polygon etc.
Vibration banding Most often:
•Constant group banding
Can also be:
•Periodic group
•Random group
Troubleshooting Checklists
•These are checklists suspected causes and possible solutions, based on banding type, and are
listed from the most likely to less common.
•Work through the recommended solutions sequentially until the issue is resolved.
•If the issue remains unresolved escalate it to your technical specialist.
Banding Cause (Causes of interference)
Causes are graded from most common to least common.
•Consumables ware and tare.
•Electrical issues.
•Writing head installation and adjustments.
•Screening and LUT calibration artifacts.
•Mechanical pressure, velocity and local loads.

EN 7
Banding troubleshooting road map
High-level usage summary:
•Define the banding type and work through the relevant troubleshooting checklist to resolve the issue.
•For details on how to use this table see the “Troubleshooting Methodology” on page 6.
For sample pictures see figures in “Appendix 1 Banding Types - Samples“ on page 15.
Cause detail
roubleshooting
Band shifting
between pages
Separations
Banding
cause
Band
grouping
Banding
Consistency
Vibration
M3
Periodic banding
(specific frequency on page)
Constant banding
(same position on page)
Random
banding
E.g. Figure 12
Constant
Single
Periodic
Single
Periodic
Group
E.g. Figure 15
Constant
Group
E.g. Figure 11
E
C2
C4
LUT
M1
M2.1
Any
cause
Often:
E
M3
WH2
In each
Separation.
E.g. Figure 9
In some
Separations
E.g. Figure 10
Shifted
between
Pages
E.g. Figure 14
Not shifted
between
Pages
E.g. Figure 13
Mechanical
M
See page 14
Local loads /
Pressure changes
See Appx. 4
M1
Gear
Transmission
See Appx. 2 & 3
M2
Electrical
E
See page 12
Screening / Machine LUT
LUT
See page 13
Consumables
C
See page 12
Writing head
WH
See page 13
PIP
foil
C1
Blanket
C2
BID
C3
Impression
paper
C4
E
C1
LUT
M1
M2.1
M1
M3 C3
WH2
WH3
M2
M3
LUT
M2.1
M2.2
WH1
Focus
WH1
Dynamic
Mirror/Prism
WH2
Other
WH3
Teeth
M2.1
Gear run-out
M2.2
ButtonBanding Troubleshooting
Repeatable
banding

8 Banding troubleshooting EN
Banding troubleshooting
Pre-troubleshooting checklist
Before troubleshooting a banding problem, it is imperative that the press is printing properly with all settings
at their nominal or default positions. Banding symptoms will be misleading, amplified or exaggerated if the
press is not set up in this way, not clean or not adjusted properly.
1. Load the banding troubleshooting diagnostic jobs onto the press computer:
•TS_1on_3off horizontal lines.jlt •TS_1on_3off vertical lines.jlt
•TS_Registration 4 pix.jlt •TS_Grey20.jlt
•TS_Banding2_Rev03.jlt
These jobs can be copied from CD or downloaded from the HP Indigo documentation portal:
http://h21021.www2.hp.com/C5/Test%20Jobs/default.aspx
2. Load the recommended paper: 100 - 150 gsm glossy paper, (minimum) size: 320 x 460 long grain.
3. Print a "base point" reference set of prints: TS_Banding2, TS_Gray20, TS_Registration 4 pix.
4. Adjust first transfer.
5. Check that the substrate thickness is defined correctly.
6. Check that the PIP foil age is below 35K impressions and installed correctly.
7. Check that the blanket age is below 25K impressions and installed correctly.
8. Perform a Machine LUT calibration.
9. Check that the impression paper is clean and installed correctly.
10. Check that the PIP break is functioning correctly.
11. Clean all BID units.
12. Check that all press gears are clear of paper, dry ink and other obstructions.
13. Check that all press gears are greased, and oiling points are oiled - daily and monthly routine.

EN Banding troubleshooting 9
Identifying the banding type
1. Print 5 copies of the following banding diagnostic jobs:
Print job Diagnostic purpose
TS_Gray20 Defining Banding Consistency
TS_Banding2 Identifying which Separations banding occurs
TS_Registration 4 pix Identify misregistration - banding is accompanied by waves – vertical misregistration
2. Throw away the 1
st
copy of each job.
3. Inspect copies from 2
nd
to 5
th
as follows:
1. Arrange the 4 copies of each job side by side on a large surface.
2. Mark major banding on each print sample.
Figure 3 TS_Gray20 job Figure 4 TS_Banding2 job
4. If the Banding consistency appears to be Random banding, the cause is probably not mechanical.
Troubleshooting:
Work through the “Random banding - troubleshooting checklist” in the “Banding troubleshooting road
map” on page 7.
5. If the Banding consistency appears to be Repeatable banding (repeated on each page or separation):
Determine if the cause of the banding is mechanical or not:
1. Print 3 copies of the TS_1on_3off horizontal lines job, and the TS_1on_3off vertical lines job.
2. Note: The TS_1on_3off horizontal lines job is extremely sensitive to banding. Ignore any new
bands that may appear. At this stage ONLY focus on the specific banding identified on the
TS_Banding2 job, TS_Gray20 job and customer jobs.
3. Compare the two jobs:
Job comparison Action
Same banding appears at the
same places on both jobs
Perform “Troubleshooting Repeatable banding with Non-
mechanical causes” on page 10.
Horizontal lines job:
• Has specific banding,
but the vertical lines job:
• None or much less
• Perform “Troubleshooting Constant banding with
Mechanical causes” on page 10.
• Perform “Troubleshooting Periodic banding” on page 11.
Inconclusive Perform “Appendix 7 Optional alternative mechanical banding
diagnostic method” on page 25.

10 Banding troubleshooting EN
Troubleshooting by banding type
Troubleshooting Repeatable banding with Non-mechanical causes
•The banding cause is probably not mechanical:
•This is because the TS_1on_3off vertical lines job is not sensitive to mechanical banding.
•But sometimes the cause could still be mechanical, caused by pressure variations. For example
BID pressure, 1
st
or 2
nd
pressure.
•The same banding appears at the same places on both jobs:
Figure 5 TS_1on_3off horizontal lines Figure 6 TS_1on_3off vertical lines
Troubleshooting:
Work through the “Troubleshooting checklists” in the “Banding troubleshooting road map”
on page 7, for the following banding causes: Electrical, Consumables or LUT.
Troubleshooting Constant banding with Mechanical causes
•The TS_1on_3off horizontal lines job has your specific banding, but the TS_1on_3off vertical
lines job does not at all or has much less:
Figure 7 TS_1on_3off horizontal lines Figure 8 TS_1on_3off vertical lines
(has banding) (has no banding)
The banding cause is probably mechanical
(due to velocity changes or image writing placement problem or image transfer).
Troubleshooting:
1. Measure the distance from the leading edge of the sheet to the banding.
2. Check if the banding is in the “Appendix 4 Constant banding table” on page 21:
•If the banding is in the table, perform the relevant “Diagnostic tips” on page 21.
•If not, the cause is probably defective or dirty gear teeth – see “Appendix 5
Troubleshooting constant banding caused by gear teeth” on page 22.

EN Banding troubleshooting 11
Troubleshooting Periodic banding
Troubleshooting:
1. Classify the Band grouping: (Single or Group).
2. Mark as many continuous bands as you can on the print sample.
3. Measure banding periods in millimeters (mm).
4. Calculate the banding frequency (in mm or Hz) - see calculation below.
5. Determine if the cause of the banding is mechanical or not:
•Print 3 copies of the TS_1on_3off horizontal lines job, and the TS_1on_3off vertical lines job.
•Note: The TS_1on_3off horizontal lines job is extremely sensitive to banding. Ignore any new
bands that may appear. At this stage ONLY focus on the specific banding identified on the
TS_Banding2 job, TS_Gray20 job and customer jobs.
•Compare the two jobs:
Job comparison Action
Same banding appears at
the same frequency on both
jobs
Horizontal lines job:
• Has specific banding,
but the vertical lines job:
• None or much less
Determine the cause of the banding as follows:
Locate the banding frequency (that you calculated above) in
“Appendix 3 Periodic banding table – caused by gears and
rotating parts” on page 19.
• If table shows that the cause is a gear then:
Identify the gear using the “Appendix 2 Gear Transmission
Schemas” on page 18.
• If the table shows that the cause is not a gear then:
Investigate the relevant component for possible defect or
malfunction.
Inconclusive Perform “Appendix 7 Optional alternative mechanical banding
diagnostic method” on page 25.
Periodic banding frequency calculation
Notes:
•Marking the bands:
•In general, mark the bottom edge of bands (or group of bands).
•Sometimes there is no clear edge. Mark the center of the bands (or group of bands).
•Measuring the distance between bands (or group of bands).
•Keep consistent - bottom edge to bottom edge, or center to center.
Steps:
1. Measure the distance between 1
st
and last band.
2. Count the number of bands (or group of bands)
on the page.
3. Apply the formulas as follows:
1
)(
−
=
N
X
mmF
)(
1218
)( mmF HzF =
Where:
F (mm) = Frequency in mm
F (Hz) = Frequency in Hertz
X = Distance between 1
st
and last band
N = Number of bands (or groups) marked
and measured on the page
1
2
3
4
5
6
7
8
X

12 Causes of Banding EN
Causes of Banding
(C) Consumables banding
There are four major causes:
Press component Possible Causes Appearance / Banding type
(C1) PIP foil
Burns, stains, short circuits,
mechanical damage and poor
installation.
Usually appears like constant banding in some
alternate separations (1
st
& 3
rd
or 2
nd
& 4
th
).
(C2) Blanket
Mechanical damage after
PSTB jams, stains, electrical /
bias contact issues and poor
installation.
Usually appears like constant banding in each
separation.
(C3) BID unit Developer roller stains, voltage
instability.
Usually appears like periodic banding shifted
between pages.
(C4) Impression paper Impression paper folded. May appear like a single constant banding.
General solutions for Consumables banding
1. Clean the BID unit.
2. Check that the PIP foil, blanket and impression paper are correctly installed.
3. Replace consumables if necessary.
(E) Electrical banding
Press
component Possible Causes Appearance / Banding type
ITM bias ITM bias instability during 1
st
transfer or short circuits on the PIP foil.
Interferes with the density of dots and / or solid areas.
Scorotrons Low charge creates random background areas around dots.
BID BID unit voltage instability.
Dark and / or light lines
that repeat down the
sheet. Usually appears as
random banding with
sharp edges.
General solutions for electrical banding
1. Look for faulty bias contacts.
2. Check that the PIP drum is grounded correctly.
3. Check for a faulty BID unit or BID power supply board.
4. Look for short circuits e.g. Blanket on ITM drum has raised areas that touch the anti-dripping tray.

EN Causes of Banding 13
(WH) Writing head banding
Press component Possible Causes Appearance / Banding type
(WH1)
Focus adjustment Faulty focus adjustment Usually produces 2.25 mm period banding.
(WH3)
• Focus adjustment.
• Image scaling adjustment.
• De-skew calibration.
0.375 mm period banding.
(WH2)
Dynamic mirror
Dynamic mirror malfunction (or
dynamic prism in the HP Indigo
press 3050).
This can cause any type of banding.
Usually accompanied by random misregistration
issues.
(WH3) Writing head
press interfaces
Faulty Writing head installation
on press interfaces.
Usually vibration banding 0.7—2.5 mm - constant
groups or periodic groups. (Especially on the HP
Indigo press 3050.)
General solutions for banding caused by the writing head
1. Adjust the writing head focus and leveling.
2. Verify that the writing head parameter files correspond to the writing head serial number.
Reinstall the writing head parameters.
3. Physically unlock the dynamic mirror according to the instruction sticker on the writing head.
4. Adjust image scaling.
5. Check the de-skew calibration.
6. Check the writing head mechanical installation.
7. Check the press installation - press wheels should not touch the floor.
(LUT) Screening and machine LUT artifact banding
•Screening banding is caused by intrinsic screening artifacts, for example:
•3.8 mm period banding on Sequin screening.
•Machine LUT banding is caused by faulty machine LUT generation.
Images most affected are screen tints that change from say 5% to 100% in a gradual way:
•Vignettes are light to dark or dark to light areas of a single color.
•Blends are composed of process colors (C, M, Y, and K) that change from one specific color to
another.
•Vignettes and blends may also exhibit some banding if they contain too many steps or if the
machine LUT is not correct.
•For example if the machine LUT was set to the following numbers:
•Step 20 is 20, step 30 is 32, step 40 is 38 and step 50 is 50. (Note that these numbers
are within normal tolerance.)
•If a vignette falls within this range, a band will be created between 30% and 40%.
•The LUT in this example, actually compresses the vignette and generates banding.
General solutions for screening and machine LUT artifact banding
1. Run the Machine LUT generation wizard.
2. Try to print with a different job screen definition for a diagnostic.
3. Replace - blanket. (Run the Machine LUT generation wizard, print again).
4. Replace - PIP (Run the Machine LUT generation wizard, print again).
5. Check the Ink density and conductivity calibration.
Run the Machine LUT generation wizard again.

14 Causes of Banding EN
(M) Mechanical interferences
There are two major mechanical interferences: local loads and gear transmission issues:
(M1) Local load
Local loads in the press reduce the velocity of, or cause pressure changes in, the set of image
processing drums, for a moment. This interferes with dot placement at sensitive stages of image
production and transfer:
•Image writing phase - Writing head to PIP drum.
•Image transfer phase - 1
st
transfer - PIP drum to ITM drum.
- 2
nd
transfer - ITM drum to impression drum.
Local loads occur at:
•Each separation - Example - at the start of 2
nd
transfer pressure.
•Some separations - Example - during paper input or output.
General solutions for banding caused by local loads – check for:
1. Correct press adjustments - For example 2
nd
pressure, gripper shaft magnets.
2. Damaged or loose parts in paper path -Gripper shaft assembly, stop station assembly.
3. ITM drum radial freedom -This may produce banding under 2
nd
transfer start or end loads. In
such cases local loads affect both pressure between drums and drum rotation speed.
4. Parts that vibrate under specific loads that may interfere with the writing head.
- For example on the HP Indigo press 3050 - stop finger noise during paper feed.
(M2) Gear transmission issues interfering with dot placement
Gear transmission issues in the drums and gears, during image writing and transfer, interferes with
dot placement. Banding patterns are created in relation to gear diameter and distance between teeth.
Gear transmission issues are cause by:
Gear transmission issue Possible symptom Possible cause
Gear meshing
Periodic banding down
the page with tooth to
tooth at a constant
frequency.
• Incorrect gear / drum assembly
• Defective gear (factory error - out of spec)
• New gear not meshing smoothly with worn gear
(M2.1) Defective gear teeth Periodic single banding
• Defective tooth
(M2.2) Gear run out (gear not
centered on its shaft)
Periodic groups of
banding
• Incorrect gear assembly
• Defective bearing (that supports the gear shaft)
Solutions for gear transmission issues:
1. Clean gears.
2. Grease gears.
3. For Direct Drive presses (HP Indigo press 3500, HP Indigo press 5000, HP Indigo press 5500):
3.1. For banding frequencies: 101.5 mm (12Hz), 50.8 mm (24Hz) and 25.4 mm (48Hz) - This
is related to the main motor, small drive gear (gear 14) and the flywheel - Run the
Harmonic and Torque compensation wizard.
3.2. If the wizard did not correct the issues then - Replace defective gears, main motor or
flywheel where necessary.
4. For non-Direct Drive press (HP Indigo press 3050) -
4.1. Replace defective gears, shafts and bearings where necessary.
There are two other mechanical interferences: pressure and vibration issues:
Pressure issues interfering with dot size
Pressure variations may interfere with dot size and also causes dot smearing.
(M3) Vibration of certain parts
Vibration of certain parts interferes with dot placement or causes dot smearing.
•E.g. 1 - BID unit vibration, 1 separation job can produce groups of 6.8 - 7.0 mm periodic banding.
•E.g. 2 - Writing head vibration usually caused by press operation or local loads. 0.7 - 2.5 mm
frequency range - constant groups or periodic groups - especially for HP Indigo press 3050.

EN Appendix 1 Banding Types - Samples 15
Appendix 1 Banding Types - Samples
Constant - Single banding
Figure 9 Each separation
Figure 10 Some separations

16 Appendix 1 Banding Types - Samples EN
Constant - Group banding
Figure 11 Constant group
Random banding
Figure 12 Random banding

EN Appendix 1 Banding Types - Samples 17
Periodic banding
Periodic - Single banding
Figure 13 Not shifted between pages Figure 14 Shifted between pages
Periodic - Group banding
Figure 15 Periodic - Group banding Figure 16 Periodic banding

18 Appendix 2 Gear Transmission Schemas EN
Appendix 2 Gear Transmission Schemas
These schemas are used to locate a gear, when you know the number of teeth in the gear.
How to use these schemas:
1. Identity the gear using the “Appendix 3 Periodic banding table – caused by gears and rotating
parts” on page 19, and get the number of teeth.
2. Locate the gear on the relevant Gear Transmission Schema for your press (see below).