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
requirements set forth herein.
This document contains valuable trade
secrets and confidential information of
Hewlett-Packard Company. Nothing herein
may be copied, reproduced or distributed in
any form or medium, or disclosed to any
third party in any manner, without prior
written authorization of Hewlett-Packard
Company. The copyright notice, which
appears in this document, is purely
precautionary and shall not be deemed to
constitute publication or intent to publish, in
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.