HP L28500 User Manual
DESIGNJET L28500 Printer Series
July 2012
For HP Internal Use Only
© 2012 Hewlett-Packard
Company
This document contains
proprietary information that is
protected by copyright. All
rights are reserved. No part of
this document may be
photocopied, reproduced, or
translated to another language
without the prior written
consent of Hewlett-Packard
Company.
2nd edition, July 2012
Warranty
The information contained in
this document is subject to
change without notice.
Hewlett-Packard makes
no warranty of any kind
with regard to this
material, including, but
not limited to, the implied
warranties of
merchantability and
fitness for a particular
purpose.
Hewlett-Packard shall not be
liable for errors contained
herein or for incidental or
consequential damages in
connection with the furnishing,
performance, or use of this
material.
WARNING
The procedures described in
this manual are to be
performed by HP-qualified
service personnel only.
Electrical Shock Hazard
Serious shock hazard leading
to death or injury may result if
you do not take the following
precautions:
- Ensure that the ac power
outlet (mains) has a protective
earth (ground) terminal.
- Disconnect the printer from the
power source before
performing any maintenance.
- Prevent water or any other
liquids from running onto
electrical components or
circuits, or through openings in
the enclosure.
Electrostatic Discharge
Refer to the beginning of
Chapter 4 of this manual, for
precautions you should take to
prevent damage to the printer
circuits from electrostatic
discharge.
WARN ING
The Warning symbol calls
attention to a procedure,
practice, or the like, which, if
not correctly performed or
adhered to, could result in
personal injury. Do not
proceed beyond a Warning
symbol until the indicated
conditions are fully understood
and met.
CAUTION
The Caution symbol calls
attention to an operating
procedure, practice, or the like,
which, if not correctly
performed or adhered to, could
result in damage to or
destruction of part or all of the
product. Do not proceed
beyond a Caution symbol until
the indicated conditions are
fully understood and met.
Customer Assurance
Customer Experience Section
Large Format Printing Division
Hewlett-Packard Espanola, S.L.
Cami de Can Graells, 1–21
08174 Sant Cugat del Vallès
Spain
Safety Symbols
General definitions of safety
symbols are given immediately
after the table of contents.
HP Designjet L28500 Printer Series
Service Manual
Table of Contents 1
Printer system 1-7
Troubleshooting 2-45
System error codes 3-89
Service test, utilities and calibrations 4-145
Print quality 5-207
Ink supplies 6-235
Service parts and diagrams 7-247
Removal and installation 8-271
Preventive maintenance 9-607
Move, repack, and store the printer 10-613
Safety precautions 11-625
Using this manual
Purpose
This Service Manual contains information necessary to test, calibrate, and service the HP Designjet
L28500 104-inch Printer (Model CQ871A).
For information about using the printer, see the User’s Guide.
Chapters
1 Printer systems
Use this chapter as a reference for technical information about the subsystems, components, and how they
work together.
Of particular importance are the diagrams included for each subsystem of the printer. They can be useful
for both troubleshooting and disassembly.
2 Troubleshooting
Whenever a printer is not functioning correctly due to a fault, use this chapter for step-by-step diagnosis
until you arrive at the solution, which may include replacing a part.
Troubleshooting always begins with a problem; so, when you enter the chapter, navigate to the proper
section and find the troubleshooting steps for your problem.
This chapter does not cover the procedures for the diagnostic tests you must perform while troubleshooting,
nor the replacement procedures you must complete to fix the problem.
3 System error codes
This chapter contains the system error codes which are displayed on the Front Panel and by the Embedded
Web Server. Each system error code shown in the chapter has a brief description and the steps required
to solve the error.
Most of the troubleshooting steps involve performing a test or a calibration, which can be found in the
following chapter. Before replacing any part that you suspect of causing the system error code, always
perform the test or calibration.
4 Tests, utilities, and calibrations
Use this chapter whenever you need to perform a diagnostic test, service utility, or service calibration. This
chapter is meant to provide procedures and relevant information, not troubleshooting information. For
troubleshooting information, see the Troubleshooting chapter.
These procedures are described in full, so that you know any relevant values for the test, as well as
information about what the printer is actually doing during the test.
The goal of diagnostic tests is to locate the root cause of the problem and the corresponding system error
code or message that will provide you with logical steps to resolution.
Some diagnostic tests or calibrations must be performed after removing a component.
5 Print quality
This chapter describes the print-quality diagnostic procedures. Further troubleshooting advice can be
found in the User’s Guide.
6 Ink supplies
This chapter describes and discusses the components of the ink supply system.
7 Parts and diagrams
The purpose of this chapter is to detail all of the available service parts of the printer. This information is
presented in tables, organized by subsystem, and includes the following:
• Official service part names
• Part numbers
• Illustrations of the service parts
Use this chapter whenever you need to order a service part.
8 Removal and installation
The purpose of this chapter is to provide procedures for removing and installing service parts. Each service
part has a removal procedure detailed in this chapter, and installation procedures and notes are included
as needed.
Useful information such as access notes and screw types (head sizes) are provided to help you work
efficiently.
9 Preventive maintenance
Maintenance alerts are displayed on the Front Panel and Embedded Web Server whenever maintenance
is required. While most of these alerts can be resolved by the customer, some require a service engineer.
Use the preventive maintenance chapter whenever you need to perform a preventive maintenance
procedure due to an alert the customer receives from the Front Panel or Embedded Web Server, or to get
reference information on life counters and maintenance that must be performed by the customer.
10 Move, store, or repack the printer
This chapter gives advice on moving, storing, and repacking the printer.
11 Safety precautions
This is an industrial printer that uses high voltages: service operations can be hazardous. The safety
chapter covers all the guidelines and checks you need to perform in order to service the printer.
You are expected to have appropriate technical training and experience necessary to be aware of
hazards to which you may be exposed in performing a task, and take appropriate measures to minimize
the risks to yourself and to other people.
Readership
The primary readers of this service manual are HP Service Engineers, although secondary readership may
include resellers. All procedures must be performed by HP Service Engineers or Authorized Service
Delivery Partners, except for those procedures clearly marked otherwise.
1 Printer systems
• Electrical system.....................................................................................................8
• Substrate path ..................................................................................................... 25
• Ink Delivery System (IDS)....................................................................................... 31
• Scan Axis and Carriage........................................................................................ 33
• Service Station and waste management .................................................................. 37
• Heating system ....................................................................................................40
• Front Panel ..........................................................................................................43
Printer Systems
Printer systems 7
Electrical system
Description
The electrical system controls all the printing systems and the heating systems inside the printer. Most parts
of the control electronics are placed inside the ’E-box’.
Printer systems
Components
The electronics can be divided into different functional subsystems and will be described accordingly.
There are 7 functional subsystems within the electronics, as shown below.
• Front Panel: The Front Panel in this printer includes a touchscreen, a power button, and a buzzer.
It is connected to three different boards on the EEbox: Formatter PCA (control), Engine PCA (power
button signal), and Mini Interconnect PCA (buzzer and power control).
• Substrate Path: Controls the substrate movement: Drive Roller and Rewinder motors, Take-Up
Reel, OMAS sensor, four Vacuum Fans (controlled by two Eola PCAs), pinch lever, and Media
Sensors.
• Scan Axis: Printhead firing control and sensors for color and substrate detection (Carriage PCA,
encoder, Tetris and SOL sensors, substrate crash sensor, and movement control using the scan motor
and its fan).
• Service Station: Printhead maintenance. It controls a motor, a drop detector, and some sensors,
including primer.
• Waste Management : Management of the waste ink and aerosol coming from the Service
Station.
• Ink Supply: Control of ink through two ISS PCAs and an intermediate PreDriver board as a buffer.
• Heating System: Dryer and Curing Resistor heater elements controlled by three sinewave
converters plus some Infrared (IR) sensors for Latex ink. The power input lines for the heating are
distributed to the rest of the printer through the EE Cabinet module.
8 Printer systems
Circuit diagram
Printer systems
E-box components
Description
The E-box contains most of the electronics of the printer.
Printer systems 9
Components
Printer systems
1. Mini interconnect PCA [Messi]
2. Formatter PCA [Torus]
3. Engine PCA [Tokamak] (similar to what was known as Sausalito)
4. OMAS PCA
5. Hard Disk Drive (HDD)
6. Power Supply Unit (PSU)
7. Extra Power Supply 24 V
8. Printmech PCA [Boomerang]
Functionality
Mini interconnect PCA
The Mini PCA is just a interconnect board with only connectors that helps distribute the power and control
signals from the Printmech board to all the elements connected to the right side of the machine, including
the following:
• Take-Up Reel
• Vacuum Fans (passes through, the actual control is inside Printmech)
• Front Panel
• TOMAS (temperature sensor for the OMAS sensor)
10 Printer systems
• Valves and motors for primer, rack engage, SVS, and Waste Management
• Top fans
• Rewinder motor
Formatter PCA
The formatter is the motherboard of the printer, and is the same type of board as for a standard PC.
Engine PCA
This board is the main controller of the printer. It is responsible for all the processes performed in real-time
and is the ultimate controller of all electromechanical systems. The Engine PCA controls all substrate path
components (Drive Roller, Spindle Motors, OMAS, etc.) and all non-substrate path components (Carriage,
Scan Axis Motor, Dryer and Curing Heaters, Print Head Cleaning Assembly, Service Station, etc).
OMAS PCA
This board controls the Optical Media Advance Sensor used to measure the substrate advance.
Hard Disk Drive (HDD)
The HDD contains the firmware of the printer.
• The operating system.
• All calibration values, product number, serial number etc, are stored on the Hard Disk Drive. In order
to make sure that this information is not lost in the case of a failure of the HDD, a backup is made in
the ISS top board
NOTE: In order to prevent any loss of calibration values, do not replace the following at the same
time:
• The Hard Disk Drive and the ISS Top Board
Power Supply Unit (PSU)
This PSU delivers power to all the parts of the printer but the heater elements. The internal rails are: 5V_sb;
3V3, 5V, 12V, 24V, and 42V.
Printer systems
Extra Power Supply Unit (24 V)
This extra PSU supplies 24 V for some extra components such as drying fans and scan motor fan.
Printmech PCA [Boomerang]
The Printmech PCA is mainly used to control all the mechatronics of the printer. For routing reasons, only
the parts connected to the left side of the printer are connected to this board:
• Scan-Axis Motor
• Media-Axis Motor
• Ink valves
• Ink pressurizing pumps
• Dryer fans
• Curing fan
• Vacuum fans
• IR sensor
• IR Fan
• Sinewave converter control
• Media Jam Sensor
The remaining functionality implemented in the printmech PCA is sent to the right side of the printer
through the Mini Interconnect PCA and its 3 cables (power + data).
Printer systems 11
Carriage Electronics
The Carriage contains the electronics for controlling and firing the Printheads. It also contains electronics
for controlling the external sensors (SOL and Tetris) as well as the Scan Axis Encoder.
The electronics of the Carriage receives power and data from the Trailing Cables, which include both
power (+45V) and data (LVDS) cables. The power cable connects the Carriage with the Printmech board
Printer systems
Components
and the data cable connects the Carriage with the Engine PCA.
Carriage PCA
The Carriage PCA contains the electronics to control how and when the ink is dropped from every
Printhead, and receives information from the sensors.
SOL Spectrophotometer
The SOL is a color sensor located on the left side of the Carriage. A metal sheet protects the SOL from the
high temperatures produced by the Dryer Assembly. The main function of the SOL is to measure color
samples that have been printed on the loaded substrate and then are placed in the print platen zone.
Before taking any color measurement, the SOL must be initialized. The SOL initialization process takes
approximately 7 minutes. This process consists of three steps:
• Sensor switch on
• Sensor warm up
• Sensor calibration
When the initialization process has finished, the shutter opens automatically and the Carriage is moved
along the Scan Axis to place the SOL on top of each sample to take a color measurement. After the
measurements, the shutter is closed again and the sensor is switched off.
Tetris
Tetris is used to align the Printheads as well as to locate the substrate edges and measure its size. The
alignment procedure consists of a series of patterns first being printed, then scanned using the Tetris, and
finally an internal process is used to correct the timing of when and where the nozzles of the Printheads
fire, and detect any possible nozzle-out issues.
Scan axis encoder
The line encoder is located on the Carriage; it measures and counts the movements of the Scan Axis. An
optical, infrared wavelength encoder is used: the same type of encoder used in most of the HP large-format
printers. The Encoder signal is converted to LVDS logic levels and directly routed through the Data TC.
12 Printer systems
Printhead Flex
To connect the Carriage to the Printheads, a delicate flexible circuit with small golden dimples is used.
Printheads are inserted into unique slots and a spring-loaded mechanism pushes the electrical contacts of
the Printheads into the Printhead flex, which subsequently connects the Printhead to the Carriage
electronics. Printhead Flexes are the most delicate and sensitive part of the Carriage. If the Printheads are
inserted with too much force or they are misaligned, the insertion can easily damage them.
Ink Supply Station (ISS) Electronics
Description
There are two ISS PCAs (as in the DJ L25500/L26500 printers) plus a new extra board in between the
ISS PCAs and the PrintMech PCA, called the Pre-Driver PCA.
Printer systems
Printer systems 13
Components
PreDriver PCA
This board receives signals from the PrintMech PCA in differential mode and translates them to singleended ones.
It has two LEDS:
Printer systems
• Green LED: 5 V present coming from the PrintMech board (cable connected)
• Red LED: Overpressure or disconnected cable to the ISS PCA
See the Troubleshooting chapter (page 52) for more details, such as the location of the LEDs.
Top and Lower ISS PCAs
The ISS electronics are powered from a +12 V line coming from the PrintMech, and a linear regulator on
the ISS PCAs generates the +5 V used to power all the devices on the board.
The ISS PCAs are two electronic PCAs located at the rear of the Ink Supply Station. The ISS PCAs provide
the following:
• Pressure Ink Level Sense (PILS) measurement
• Ink supply presence detection
• Ink Cartridge broken bag detection
• Ink supply smart chip interface
• Air pressure measurement and air pump shutdown
• Humidity and temperature measurements
• System back-up EEPROM
14 Printer systems
Below is a picture showing the connections and components located at the rear of the ISS.
Marking Description
Printer systems
AISS Top PCA
BISS Lower PCA
CPre-Driver PCA
D Cable: ISS Top PCA to Pre-Driver PCA
E Cable: Pre-Driver PCA to PrintMech PCA (blue)
F Cable: ISS Top PCA to ISS Lower PCA
G Cables (6): ISS PCAs (Top and Lower) to Ink Cartridges
H ISS grounding cable
Both top and lower ISS PCAs share the same PCB, the only difference between them is that the lower PCA
is a simplification of the top PCA: the top PCA contains these additional parts:
• EEPROM
• Connection from the PrintMech PCA
• Air pressure sensor
• Temperature and Humidity sensors
Both PCAs are connected through an 8-pin connector. The 2nd ISS connector is connected to the
PrintMech PCA in a daisy-chained connection, the 1st ISS board by means of this 8-pin connector.
Vacuum Fan electronics
Description
There are two Eola PCAs to control 4 different brushless blowers in order to generate the required vacuum
to hold the substrate. One of the Eola PCAs is connected to the Printmech PCA (left side of the printer) and
the other one to the Mini Interconnect PCA (right side).
Printer systems 15
Waste Management Electronics
Description
There is a small interconnect board (WM PCA) to connect the aerosol fan and two switches used in the
waste management system (as in the DJ L26500). This board is connected to the EEbox through the Mini
Interconnect PCA. There is an intermediate connector in the Ebox chassis to allow customers to connect
Printer systems
the cable during installation.
Heating System Electronics
Description
The heating system provides the power to the heater elements in order to dry and cure the jobs.
The amount of power used for heating requires a three-phase power system.
Components
• Terminal block
• Main Switch
• 3 x RCBs
• 3 x Sine wave converters
• Drying & curing resistors
• Thermal switches
• IR sensors (for curing and heating)
• IR sensor curing cooling fan
• 2 x Window switches x Sine wave converters
• Curing and Drying fans
INPUT Circuit diagrams
The heating components form a high voltage system, so they are protected by their own enclosure (EE
cabinet) for safety.
16 Printer systems
A simplified block diagram of the input stage of the heater system (EE cabinet) is shown in the following
picture:
Printer systems
Terminal block
The terminal block is used to configure the printer depending on the customer's mains configuration. It has
some jumpers used to perform the configuration. The input power cables from the customer's installation
(not provided with the printer) are connected within this terminal block.
NOTE: An electrician is required for the setup and configuration of the building's electrical system
used to power the printer and also for printer installation. Make sure that your electrician is
appropriately certified according to local regulations and supplied with all the information regarding
the electrical configuration.
Remember that you are required to follow the local laws, regulations and standards that pertain to the
electrical installation of your printer.
Electrical power system
The printer requires three-phase power, which provides a more efficient means of supplying large
electrical loads than single-phase power. There are two possible configurations depending on input
voltage range, as described below.
Printer systems 17
380–415 V three-phase line-to-line configuration
Three-phase line specifications
Number of power wires 5 (3 lines + 1 neutral + 1 PE)
Input voltage (line-to-line) 380–415 V (–10%+6%)
Printer systems
Input frequency 50/60 Hz
Power consumption 8 kW
Maximum load current (per phase) 24 A
Circuit-breaker specifications
Branch circuit-breaker
Three-phase 4 poles, 30–32 A
AC power cable specifications
Three-phase line
Configuration 5 wires, L1/L2/L3/N/PE
Wire Strained Cu, minimum 4 mm² or 10 AWG
Terminals Lines: ferrule terminals, PE: M6 ring terminal
External diameter range 15–25 mm
Jumper configuration
18 Printer systems
200–240 V three-phase line-to-line configuration
Three-phase line specifications
Number of power wires 4 (3 lines + 1 PE)
Input voltage (line-to-line) 200–240 V (±10%)
Input frequency 50/60 Hz
Power consumption 8 kW
Maximum load current (per phase) 40 A
Circuit-breaker specifications
Branch circuit-breaker
Three-phase 3 poles, 50 A
AC power cable specifications
Three-phase line
Printer systems
Configuration 4 wires, L1/L2/L3/PE
Wire Strained Cu, minimum 6 mm² or 8 AWG
Terminals Lines: ferrule terminals, PE: M6 ring terminal
External diameter range 15–25 mm
Jumper configuration
Printer systems 19
200–240 V single-phase or bi-phase line-to-line configuration
IMPORTANT: HP strongly recommends using three-phase power to connect the printer, as described in
the Site Preparation Guide and in the flier included in the printer’s box.
The following procedure in this document describes connection options that should be limited to locations
where three-phase power is not available. Compliance must be verified and approved by a certified
electrician according to local regulations.
Printer systems
The 200–240 V installation described in this chapter requires a line capable of delivering up to 10 kW,
which is the maximum consumed by the printer during the warm-up processes.
The power line needs to support 48 A, and the branch circuit breaker must be rated for 60–63 A.
If the customer cannot connect to a three-phase system, it is still possible to connect to a bi-phase or singlephase installation if the following requirements are met and approved by an electrician.
Single- or bi-phase line specifications
Number of power wires 3 (2 lines + 1 PE)
Input voltage (line-to-line) 200–240 V~ (±10%)
Input frequency 50/60 Hz
Power consumption 8 kW
Maximum load current (per phase) 48 A
Circuit-breaker specifications
Branch circuit-breaker
Single- or bi-phase 2 poles, 60/63 A
AC power cable specifications
Single- or bi-phase line
Configuration 3 wires, L1/N/PE or L1/L2/PE
Wire Strained Cu, minimum 10 mm² or 6 AWG
Terminals Lines: ferrule terminals, PE: M6 ring terminal
External diameter range 14–25 mm
20 Printer systems
Jumper configuration
110–130 V single-phase line-to-line configuration
IMPORTANT: HP strongly recommends using three-phase power to connect the printer, as described in
the Site Preparation Guide and in the flier included in the printer’s box.
Printer systems
The following procedure in this document describes connection options that should be limited to locations
where three-phase power is not available. Compliance must be verified and approved by a certified
electrician according to local regulations.
The 110–130 V installation described in this chapter requires a line capable of delivering up to 11 kW
and a transformer for the appropriate power rating. 10 kW is the maximum consumed by the printer
during the warm-up processes, and a 10% power loss in the transformer is assumed.
The power line needs to support 100 A, and the branch circuit breaker must be rated appropriately.
If only single phase 110–130 V power is available, then a transformer is required. The proposed
specifications are:
• Input: 110–130 V, 100 A, 11 kW approximately, assuming 90% transformer efficiency
• Output: 200–240 V, 50 A, 10 kW
The setup of the printer connections in the output line of the transformer is the same as in the previous
section, “200–240 V single-phase or bi-phase line-to-line configuration”.
Printer systems 21
Power cable and Power Distribution Unit (PDU) requirements
These are the requirements for power cable and Power Distribution Unit described in the Site Preparation
Guide:
Printer systems
1. Three-phase power cable longer than 16 ft (5 m) (not supplied)
2. Power Distribution Unit (PDU) including three-phase branch circuit breaker
NOTE: The PDU must be rated to meet the power requirements of the printer, and should be in
accordance with the Electrical Code requirements of the local jurisdiction of the country where the
equipment is installed.
Power cable details and power cable length
The specified power cable length (16 ft, 5 m) in the Site Preparation Guide is not arbitrary. Since the
printer can be directly branched to the PDU and installed with its back against the wall, it is important to
have enough cable to enable proper service of the printer, if necessary. The picture below shows an
example of a printer with a proper power cable installation.
The printer can thus be separated from the wall to service the systems that are accessed from behind.
22 Printer systems
Power Distribution Unit
Find below an example of a compliant PDU in Western Europe: 380–415 VAC, 30–32 A per phase, 5
wires (3 lines, Neutral, and PE). In this example, the setup includes:
1. Three-phase Branch Circuit Breaker, as described in the Site Preparation Guide
2. Residual Current Circuit Breaker
3. Three-phase power plug
• The Residual Current Circuit Breaker (2) adds one level of safety to the operation of the printer.
• The power plug (3) is not required but convenient to service the printer if necessary, allowing the
service engineer to unplug and move the printer, to repair it safely.
Main Switch
The Main Switch is used to switch the whole printer on or off, including all the printer electronics.
Residual Circuit Current Breaker (RCCB)
To protect the printer and the users, there are three Residual Circuit Current Breakers (RCCB), which are
connected between the main power switch and the Sine Wave Converter module. They detect a current
leak greater than 30 mA. Customers can reset the RCCB if a circuit blows, but a frequent reoccurrence
indicates an electrical failure in one or more of the heaters.
Printer systems
Sinewave converters
These three modules convert the input voltage from the mains to a voltage in the output that is controlled
by the EEbox depending the quantity of power required to each of the resistors connected to them.
Each converter has three cables: One power cable for the input, another one for the output power, and
finally the control cable. The control part of the converter that interfaces with the Printmech is powered at
24 V from the printmech PCA through the control cable and through both switches placed in the window
cover of the printer. This cover has to be closed to allow the converters to work.
Each converter has 3 LEDs: Status (off or fault), PWM (if power is being delivered to the output) and ACOK
(if Vin is in range).
Output circuit diagrams
The following diagrams show the connections between the converters and the heating elements.
Printer systems 23
Drying
Printer systems
Curing
24 Printer systems
Substrate path
Description
The substrate path moves the substrate from the input spindle to the take-up reel, through the print path,
while the Carriage prints on the substrate. The objectives of the substrate path while advancing the
substrate are:
• Maintain an accurate advance
• Maintain a constant advance
• Keep the substrate flat
• Advance the substrate straight along the substrate axis
Substrate path workflow overview
The following steps describes the substrate path workflow.
1. The substrate is loaded onto the Input Spindle (1), which is driven by the rewinder mechanism to pro-
vide back tension to the substrate. The substrate is fed through the Input Platen, around the Drive Roller
(2), under the Pinchwheels (3), over the printzone and Overdrive (4), and finally it is either left free
or looped through the Tension Bar (6) and the Diverter (7) to be collected on the Take-Up Reel (8).
Printer systems
2. The Rewinder has a motor that primarily acts as a brake to maintain tension on the substrate. The
Rewinder may turn in either direction, depending on which is the printable side of the input substrate roll
and its winding direction.
3. The Drive Roller also has a motor, and is the primary component that advances the substrate. The sub-
strate is pressed to the drive roller by the pinchwheels, ensuring a smooth substrate advance. The motor
receives feedback from an encoder located at the left side of the roller, inside a protected enclosure on
the left of the left sideplate.
4. The surface of the substrate path where the substrate is printed is called the Print Platen. The Print Platen is
designed to give minimal resistance to the substrate advance, and includes suction holes that apply vacuum to the substrate.
Printer systems 25
5. The printer detects and controls the substrate advance. The OMAS sensor, located on a special cut-out
section of the Print Platen, is a sensor that is able to detect very small errors in the advance of the substrate. These errors are communicated to the motors on the Drive Roller, and small correctional adjustments are applied to the movement of the substrate.
In the same area, but not visible from outside the printer, is the TOMAS sensor that measures the
temperature in the area and helps OMAS to provide the drive motors with a high degree of accuracy.
Printer systems
6. The vacuum is calibrated according to the substrate type and print options used. It draws the substrate to
the Print Platen, making sure that the substrate is flat. The substrate is also under the dryer when it is in the
print zone.
7. The area of the platen in front of the print zone holds the Overdrive wheels. This area also has vacuum to
ensure traction over the wheels, which are connected to the Drive Roller through a set of gears. The Overdrive wheels help to remove the substrate from the print zone during substrate advance.
8. After the platen, the substrate goes through the curing zone and finally leaves the printer, either to be col-
lected on the Take-Up Reel or to be cut.
9. When the Take-Up Reel is in use, the substrate must be threaded first under the swiveling Tension Bar and
rerouted to the output roll around the fixed Diverter roller. This system creates tension on the outgoing substrate for proper winding. The Take-Up Reel can operate in both directions with the Rewinder, winding
with the printed face outside or inside. Weights on the Tension Bar arms may be slid forward in order to
create higher tension for textile substrates.
Startup, substrate load, substrate selection
During startup, the printer checks that the substrate path components are functioning correctly. When
shutting down, if a substrate is loaded, the printer remembers the substrate definition. This may be
modified through the front panel with the option ’Change loaded substrate’ from the substrate menu list.
NOTE: The OMAS sensor cannot see the fibers on some substrates, such as transparent
substrate or very dark or very reflective substrates. In these cases, the OMAS sensor
can be disabled. To disable the OMAS sensor
See page 182.
During substrate loading the printer may ask the user two interactions:
1. To rewind manually the substrate: The printer automatically checks the direction of the loaded sub-
strate (printed face outwards or printed face inwards). If the ’curve’ of substrate is too large the
printer cannot detect it and the printer asks the user to rewind manually. Once the substrate is
rewound the printer can detect automatically
2. To align the substrate in order to avoid skew: the printer measures skew. If the skew is too large the
printer will ask the user to lift the pinchwheels (big blue lever on right hand side) and align the substrate. The substrate must be aligned against itself (substrate edge must be aligned with input roll
edge).
26 Printer systems
Components
Spindle
The spindle can load 3” core rolls. It holds the core of the roll when its rubber bands are nipped between
the core of the roll and the aluminum extrusion.
The hub on the left side has two possible fixed positions: the end position allows loading maximum width
rolls, but there is a second position at 2.6 inches (65 mm) from the end that can be selected.
The right hub can be set along any length of the spindle so any length of roll can be loaded.
The right end of the spindle contains a gear which is used to transmit the movement from the rewinder to
the roll.
Printer systems
Spindle latch
The spindle latch prevents the substrate roll from slipping from its position when
printing. It is not necessary to close it when inserting the spindle, it closes
automatically. But the user must lift the small blue lever in order to release the
spindle and extract the roll of substrate.
Rewinder
The rewinder motor keeps a constant tension on the input substrate to
prevent skew problems. There is a motor and a transmission that gives
torque to the spindle in order to provide the necessary back tension.
Media sensor
The Input Platen has a lever that activates the media sensor whenever substrate is present. When the
substrate is inserted into the entry area, the sensor is activated and the drive roller starts turning to help
the loading process. The substrate load process has been triggered and the printer will provide instructions
through the front panel.
Printer systems 27
OMAS sensor (media advance sensor)
OMAS
location
OMAS
OMAS sensor
TOMAS sensor
location
OMAS is located under the third platen slab from
the right, only the top window can be seen:
OMAS is composed of two parts: the sensor and
its optics located under the platen and a PCI
control board on the main electronics box. Both
Printer systems
are connected through a ribbon cable that runs
through the vacuum beam, by the right sideplate
and into the electronics box.
The optical sensor detects the surface of the back
of the substrate as it moves across the platen. The
sensor is able to evaluate the exact movement of
the substrate, and communicate any small
adjustments required by the system to move the substrate accurately.
The window of the OMAS sensor must be cleaned of dust and ink to work correctly. The cleaning
procedure is described in the User’s Guide, in the section ‘Clean the substrate-advance sensor window’.
During the substrate load, the printer detects that the substrate has
reached the print platen when the OMAS captures its image.
NOTE: The OMAS sensor cannot detect the surface of some
substrates, such as plastic or very dark ones. In these cases, the
OMAS sensor must be disabled, and instead the printer uses
feedback from the Driver Roller encoder to calculate the substrate
advance. To disable the OMAS sensor, locate the OMAS Sensor
selector from the print options menu of the RIP and set it to OFF. This
can also be done from the Service menu page 182.
TOMAS
To compensate for temperature changes and mechanical expansion,
OMAS receives a temperature reading from TOMAS sensor.
Drive roller and motor
The drive roller and motor advance the substrate through the substrate path. The motor requires 42 V, and
is controlled by the Printmech PCA.
The drive roller receives the torque from the motor through a worm as in the Z6100 and other Designjets.
Because of the extension to 104 inches, the roller now has two intermediate supports.
Drive Roller Encoder Disc and Encoder PCA
The Drive Roller Encoder Disc and Encoder PCA provide the feedback system for the Drive Roller.
28 Printer systems
• The Encoder disc is a round disc mounted to the left end of the Drive Roller.
• The Encoder PCA is mounted with a sensor that reads the encoder movements of the disc (the disc
turns with the drive roller).
Pinchwheels
The pinchwheels press the substrate against the Drive Roller to make sure that the Drive Roller can advance
the substrate correctly.
• The pinchwheels are activated with the blue lever at the right side of the substrate roll and usually do
not have to be lifted unless to correct skew during substrate load or to clear jams.
• The pinchwheel system has a sensor that detects if the system is up or down.
Vacuum Pump, Vacuum Tube Assembly, Vacuum Beam
The print zone is the area of the substrate path where the transmission of ink to the substrate occurs. The
main function of the system can be defined as providing the surface where the substrate is printed, keeping
it controlled during the process, playing a main roll on the final IQ of the plots and on the operational
reliability of the printer. The subsystem is composed of the print platen assembly (including the overdrive
wheels), which is the physical interface with the substrate, and the vacuum system which is the mechanical
system where the vacuum pressure used to control the substrate is generated and conduced.
The HP Designjet L28500 printer requires a hot print zone (with additional airflow) to allow the
evaporation of the majority of the water in the latex inks. This feature, plus the new substrates supported,
changes a little the main contributors of the cockle control and substrate expansion from former products
and also adds new issues such as the thermal marks. The platen gives a convenient shape to the heated
substrate, avoiding differential temperatures due to platen conductivity.
Printer systems
The main components are:
• OVD & Platen Assembly 104” including:
• 12 DJ L26500 printer platen + 1 OMAS platen + 2 interplaten 60 + 1 platen right end + 1
platen left end
• Linear blade 104” + springs (same as DJ Z6100 or L26500)
• OVD shafts and wheels (same as DJ Z6100, with some new segments)
• Foams, foam fillings, and foam wall
• Magnets under the platen to hold Media Edge Holders
• ESD brushes
• OVD gears in brass
• Right Vacuum Fan Assembly with Eola Control Board (same as DJ Z6200 or T7100)
• Left Vacuum Fan Assembly with Eola Control Board (new)
Printer systems 29
Related tests, utilities, and calibrations
• Rewinder test page 154
• Drive Roller test page 155
• Substrate Path sensor test page 156
• Vacuum Test
• OMAS Test page 158
Printer systems
• Rewinder Motor polarity test
• Substrate path menu page 182
• Substrate advance adjustmentpage 190
Service parts
• Drive Roller page 265.
• Media Path Assemblies page 266.
• Center guide Pinchwheels Assemblies page 267.
• Media Entry Assemblies page 268.
• Take-up reel Assemblies page 269.
Removal and installation
• Rewinder page 351.
• Vacuum Fan page 356.
• OMAS page 432.
• TOMAS page 438.
• Output Platen page 524.
• Print Platen page 530.
• Input Roller page 542.
• Output Roller page 554.
• Media Sensor page 557.
• Pinchwheel Assemblypage 569.
• Center Guidepage 575.
• Driver Rollerpage 575.
• Rollfeed Modules page 582.
• Take-up reel page 582.
30 Printer systems
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