HP Indigo press 3050, Indigo press 3500, Indigo press 5500, Indigo press 5000 Troubleshooting Manual

HP Indigo press series 5000 and HP Indigo press series 3000

Banding

Troubleshooting Guide

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

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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

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

EN Contents 3

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 gennady.meltser@hp.com.

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.

4 Preface EN

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.

Writing head

Leading edge

5 visible bands

Figure 1 Banding across page width

Laser beams

Left scorotron

PIP drum sholder

Impression drum

PIP drum gear teeth

Cleaning station

ITM drum

Paper entering the paper path

Figure 2 Image processing system

EN Introduction 5

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

Constant banding

Periodic banding

Vibration banding

Electronic, Electrical failures:

• Short circuits

• Faulty or unstable bias contacts

• Static charge breakthrough

• Faulty grounding, etc…

• Local loads

• Faulty consumables

Gear transmission:

• Gear or pully

Most often:

• Constant group banding

• Dynamic mirror / prism

malfunction

• Encoder malfunction

• Main drive / controller

malfunction

• Drum teeth issues

Rotating parts:

• BID unit

• Cleaning station

• Writing head polygon etc.

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.

6 EN

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.

ButtonBanding Troubleshooting

Banding Consistency

Band grouping

Separations

roubleshooting

Random

banding

E.g. Figure 12

Any cause Often:

E M3 WH2

Constant

In each

Separation

E.g. Figure 9

E C2 C4 LUT M1 M2.1

Constant banding

(same position on page)

Constant

Single

Separations

E.g. Figure 10

In some

E C1 LUT M1 M2.1

Group

E.g. Figure 11

Repeatable

banding

Not shifted

between

Pages

E.g. Figure 13

M1 M3

Periodic banding

(specific frequency on page)

Periodic

Single

Shifted

between

Pages

E.g. Figure 14

LUT M2.1 M2.2 WH1

Periodic

Group

E.g. Figure 15

Band shifting

between pages

WH2 WH3 M2 M3

Banding cause

PIP

Blanket

foil

Cause detail

Consumables

See page 12

Impression

BID

paper

Electrical

See page 12

Focus

WH1

Writing head

See page 13

Dynamic

Mirror/Prism

WH2

Screening / Machine LUT

LUT

See page 13

Other

WH3

Local loads /

Pressure changes

See Appx. 4

Mechanical

See page 14

Gear

Transmission

See Appx. 2 & 3

Teeth

M2.1

Vibration

Gear run-out

M2.2

EN 7

+ 21 hidden pages