Microsoft and Windows are trademarks of
Microsoft Corporation in the U.S. and other
countries.
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.
This document contains proprietary
information that is protected by copyright.
No part of this document may be
photocopied, reproduced, or translated to
another language without the prior written
consent of Hewlett-Packard Company.
First Edition (February 2013)
Document Part Number: 722928-001
About This Book
WARNING!Text set off in this manner indicates that failure to follow directions could result in bodily
harm or loss of life.
CAUTION:Text set off in this manner indicates that failure to follow directions could result in
damage to equipment or loss of information.
NOTE:Text set off in this manner provides important supplemental information.
iii
iv About This Book
Table of contents
1 Product features ............................................................................................................................................. 1
Standard features ................................................................................................................................. 1
Front panel components ....................................................................................................................... 1
Appendix A Specifications .............................................................................................................................. 19
Appendix B Security provisions ..................................................................................................................... 20
Securing the digital signage player .................................................................................................... 20
Appendix C Mounting the digital signage player .......................................................................................... 21
HP Quick Release .............................................................................................................................. 21
Important service repair information ................................................................................................... 29
Index ................................................................................................................................................................... 30
vi
1Product features
Standard features
Thank you for purchasing an HP digital signage player. We hope you have years of use from our HP
MP4 Digital Signage Players. Our goal is to provide you with award-winning digital signage players
that are easy to deploy and manage with the power and reliability you expect.
The digital signage players exhibit the following features:
no diskette drives
●
●5-minute setup time
central deployment and management using a broad range of easy and scalable remote
●
management solutions
Front panel components
Figure 1-1 HP MP4 Digital Signage Player front panel components
(4)Universal serial bus (USB) connectors (2) 2.0(9)Cable lock slot
(5)Universal serial bus (USB) connectors (2) 3.0(10)Power connector
Installing the rubber feet
CAUTION:To prevent loss of performance or damage to the digital signage player, be sure to
install the rubber feet before operating the digital signage player in a horizontal orientation.
To install the rubber feet:
1.As you face the front of the digital signage player, lay the digital signage player on its left side.
2.Remove the feet from their backing.
2Chapter 1 Product features
3.Press each foot down securely onto a corner of the right side of the digital signage player.
Figure 1-3 Installing the rubber feet
Installing the stand
If the digital signage player will be installed in an vertical orientation and it will not be mounted, the
stand should be installed for stability.
To install the stand:
1.Turn the unit upside down.
2.Locate the slots on the bottom of the unit into which the tabs on the stand fit.
3.Insert the tabs into the slots, and then slide the stand about 1.26 cm (1/2 inch) toward the front
of the unit until it locks into place.
Figure 1-4 Installing the stand
Installing the stand3
Removing the stand
To remove the stand:
1.Turn the unit upside down.
2.Press the tab (1), and then slide the stand about 1.26 cm (1/2 inch) toward the back of the unit
and lift the stand (2) off the unit .
Figure 1-5 Removing the stand
Using the power cord retention slot
To prevent accidental disconnection, press a loop of the power cord into the power cord retention
slot.
Figure 1-6 Power cord retention slot (example showing horizontal orientation)
4Chapter 1 Product features
Using the keyboard
Figure 1-7 Keyboard features
(1)Caps Lock keyActivates/deactivates the Caps Lock feature.
(2)Scroll Lock keyActivates/deactivates the Scroll Lock feature.
(3)Num Lock keyActivates/deactivates the Num Lock feature.
(4)Ctrl keyUse in combination with another key; its function depends on the
(5)
Windows® Logo Key
(6)Alt keyUse in combination with another key; its function depends on the
(7)
Application key
(8)Editing keysIncludes the following: Insert, Home, Page Up, Delete, End, and Page
1
Available in select geographic regions.
1
1
application software you are using.
Opens the Start menu in Windows. Use in combination with other keys
to perform other functions. For more information, see
Key on page 6.
application software you are using.
Similar to the right mouse button, opens pop-up menus in a Microsoft®
Office application. May perform other functions in other software
applications.
Down.
Hold Ctrl and Alt while pressing Delete to restart the digital signage
player.
Windows Logo
Using the keyboard5
Windows Logo Key
Use the Windows Logo Key in combination with other keys to perform certain functions available in
Windows operating systems.
Windows Logo Key + TabSwitch between open items.
Windows Logo Key + eOpen My Computer.
Windows Logo Key + fSearch for a file or folder.
Windows Logo Key + Ctrl + fSearch for computers.
Windows Logo Key + mMinimize all windows.
Windows Logo Key + Shift + mUndo minimize all.
Windows Logo Key + BreakDisplay the System Properties dialog box.
Windows Logo Key + rOpen the Run dialog box.
Additional function keys
The following key combinations also work on HP digital signage players:
Alt + EscCycles through minimized applications.
Alt + TabCycles through open applications.
Alt + Shift + TabSwitches to the previous session.
Serial number location
Every digital signage player includes a unique serial number located as shown in the following
illustration. Have this number available when contacting HP customer service for assistance.
Figure 1-8 Serial number location
6Chapter 1 Product features
2Hardware changes
General hardware installation sequence
To ensure the proper installation of digital signage player hardware components:
1.Back up any data, if necessary.
2.If the digital signage player is powered on:
a.Turn the unit and any other attached devices off.
b.Disconnect the power cord from the wall outlet.
c.Disconnect any external devices or cables, such as a cable lock.
WARNING!To reduce the risk of personal injury from electrical shock and/or hot surfaces, be
sure to disconnect the power cord from the wall outlet and allow the internal system components
to cool before touching.
WARNING!To reduce the risk of electrical shock, fire, or damage to the equipment, do not
plug telecommunications or telephone connectors into the network interface controller (NIC)
receptacles.
CAUTION:Static electricity can damage the electronic components of the digital signage
player or optional equipment. Before beginning these procedures, ensure that you are
discharged of static electricity by briefly touching a grounded metal object. See
discharge on page 28 for more information.
Electrostatic
3.Remove the stand, if it is installed. See Removing the stand on page 4 for more information.
4.Remove the side access panel and metal side cover, if necessary. See
the side access panel and metal side cover on page 8 for more information.
5.Remove any hardware that you will replace.
6.Install or replace equipment. For removal and replacement procedures, see the following
sections:
Removing and replacing the battery on page 11
●
●
Installing a SODIMM on page 12
Installing a flash memory module on page 16
●
NOTE:Option kits include more detailed installation instructions.
7.Replace the side access panel and metal side cover. See Removing and replacing the side
access panel and metal side cover on page 8 for more information.
8.Install the stand, if you will be using the digital signage player unmounted in a vertical
orientation. See
9.Reconnect any external devices and power cords.
10. Turn on the monitor, the digital signage player, and any devices you want to test.
Installing the stand on page 3 for more information.
Removing and replacing
General hardware installation sequence7
11. Load any necessary drivers.
NOTE:You can download select hardware drivers from HP at http://www.hp.com/country/us/
eng/support.html.
12. Reconfigure the digital signage player, if necessary.
Removing and replacing the side access panel and metal
side cover
Removing the side access panel
WARNING!Before removing the side access panel, ensure that the digital signage player is turned
off and the power cord is disconnected from the electrical outlet.
To remove the left or right access panel:
1.Remove the stand, if it is installed. See
2.Press the tab on the bottom cover (1), and then slide the cover (2) back and lift it off the chassis.
Figure 2-1 Removing the bottom cover
3.Lay the digital signage player on its side on a secure working surface.
Remove the right side access panel to remove or install a SODIMM.
●
Remove the left side access panel to:
●
Removing the stand on page 4 for more information.
Remove or replace the battery
◦
Install or remove a flash memory module
◦
8Chapter 2 Hardware changes
4.Slide the access panel about 6.35 mm (1/4 inch) toward the bottom of the unit, and then lift the
access panel up and off the chassis.
Figure 2-2 Removing the side access panel
Removing the left metal side cover
NOTE:Do not remove the metal side cover to install a SODIMM. The SODIMM compartment is in
the right side of the chassis.
You must remove the metal side cover to access internal components such as the battery or to install
a flash memory module.
1.Push the tab (1) in the front edge of the side cover toward the back to release the cover.
2.Lift the front edge of the metal side cover (2), then pull the cover (3) to the front and lift it off the
chassis.
Figure 2-3 Removing the metal side cover
Removing and replacing the side access panel and metal side cover9
Replacing the left metal side cover
1.Place the metal side cover on the chassis, rear edge first, making sure to insert the two tabs of
the rear edge into the notches in the chassis (1).
2.Align the tabs on both sides of the cover and press the front edge (2) down firmly until the latch
closes.
Figure 2-4 Replacing the metal side cover
Replacing the side access panel
To replace the access panel:
1.Place the access panel on the side of the unit, offset about 6.35 mm (1/4 inch) toward the top of
the unit, allowing the hooks (1) on the underside of the panel to slip into notches in the side
access panel.
2.Slide the panel (2) toward the bottom of the unit until it locks into place.
Figure 2-5 Replacing the side access panel
10Chapter 2 Hardware changes
3.Turn the chassis upside down. Align the hooks (1) on the underside of the bottom cover with the
slots in the chassis and press the cover (2) down and then forward until it locks in place.
Figure 2-6 Replacing the bottom cover
4.Replace the stand, if the digital signage player is to be used in the tower orientation.
Removing and replacing the battery
Before beginning the replacement process, review General hardware installation sequence on page 7
for procedures you should follow before and after installing or replacing hardware.
WARNING!You must remove the left side panel to access the battery. Before removing the side
access panel, ensure that the digital signage player is turned off and the power cord is disconnected
from the electrical outlet.
To remove and replace the battery:
1.Locate the battery on the system board.
Removing and replacing the battery11
2.To remove the battery, pull the metal clamp (1) extending above the battery aside and lift the
battery (2) out.
Figure 2-7 Removing and replacing the internal battery
3.To insert the replacement battery, position it with the positive side facing the chassis wall. Slide
the battery down into the slot until the clamp snaps over the edge of the battery.
HP encourages customers to recycle used electronic hardware, HP original print cartridges, and
rechargeable batteries. For more information about recycling programs, go to
www.hp.com/recycle.
Batteries, battery packs, and accumulators should not be disposed of together with the general
household waste. In order to forward them to recycling or proper disposal, please use the public
collection system or return them to HP, an authorized HP partner, or their agents.
The Taiwan EPA requires dry battery manufacturing or importing firms, in accordance with Article 15 or
the Waste Disposal Act, to indicate the recovery marks on the batteries used in sales, giveaways, or
promotions. Contact a qualified Taiwanese recycler for proper battery disposal.
Installing digital signage player options
Various options can be installed on the digital signage player:
Installing a SODIMM on page 12
●
●
Installing a flash memory module on page 16
Installing external drives on page 18
●
Installing a SODIMM
The computer comes with double data rate 3 synchronous dynamic random access memory (DDR3SDRAM) small outline dual inline memory modules (SODIMMs).
12Chapter 2 Hardware changes
The memory sockets on the system board can be populated with up to two industry-standard
SODIMMs. These memory sockets are populated with at least one preinstalled SODIMM. To achieve
the maximum memory support, you can populate the system board with up to 4 GB of memory.
support CAS latency 9 DDR3 1600 MHz (9-9-9 timing)
●
contain the mandatory Joint Electronic Device Engineering Council (JEDEC) specification
●
In addition, the computer supports:
2 Gbit non-ECC memory technologies
●
single-sided and double-sided SODIMMS
●
SODIMMs constructed with x8 and x16 devices; SODIMMs constructed with x4 SDRAM are not
●
supported
NOTE:The system will not operate properly if you install unsupported SODIMMs.
Before beginning the replacement process, review General hardware installation sequence on page 7
for procedures you should follow before and after installing or replacing hardware.
WARNING!You must remove the right side panel to access the SODIMM compartment. Before
removing the side access panel, ensure that the digital signage player is turned off and the power
cord is disconnected from the electrical outlet.
CAUTION:You must disconnect the power cord and wait approximately 30 seconds for the power
to drain before adding or removing memory modules. Regardless of the power-on state, voltage is
always supplied to the memory modules as long as the computer is plugged into an active AC outlet.
Adding or removing memory modules while voltage is present may cause irreparable damage to the
memory modules or system board.
The memory module sockets have gold-plated metal contacts. When upgrading the memory, it is
important to use memory modules with gold-plated metal contacts to prevent corrosion and/or
oxidation resulting from having incompatible metals in contact with each other.
Static electricity can damage the electronic components of the computer or optional cards. Before
beginning these procedures, ensure that you are discharged of static electricity by briefly touching a
grounded metal object. For more information, refer to
When handling a memory module, be careful not to touch any of the contacts. Doing so may damage
the module.
To install the SODIMM:
NOTE:Populate the SODIMM sockets in the following order: SODIMM1, then SODIMM2.
1.Slide the serial number tab out of the way.
Electrostatic discharge on page 28.
NOTE:Be sure not to lose this tab.
Installing digital signage player options13
2.Pull the front of the access plate up, and lift it off the digital signage player.
Figure 2-8 Removing the SODIMM access plate
3.Align the notched edge of the SODIMM with the tab in the socket.
CAUTION:To prevent damage to the SODIMM, hold it by the edges only. Do not touch the
components on the SODIMM, and do not bend the SODIMM.
4.Hold the SODIMM at approximately a 20-degree angle, and then press the SODIMM into the
socket (1) until it is seated. Gently apply pressure to both the left and right edges of the
SODIMM (2) until the retention clips snap into place.
NOTE:A SODIMM can be installed in only one way. Match the notch on the SODIMM with the
tab on the socket.
Figure 2-9 Installing a SODIMM
5.Press the SODIMM down into the compartment.
14Chapter 2 Hardware changes
6.If you are installing the SODIMM in the HP MP4 Digital Signage Player, place a thermal pad on
the SODIMM.
CAUTION:The thermal pad is required to help cool the SODIMM in the HP MP4 Digital
Signage Player.
Figure 2-10 Installing the thermal pad in the HP MP4 Digital Signage Player
7.Insert the tab on the front edge of the access plate into its slot (1) and press the plate down
lightly to engage the latch (2).
Figure 2-11 Replacing the SODIMM access plate
8.Slide the serial number tab back to its original position.
Installing digital signage player options15
Installing a flash memory module
Before beginning the installation process, review General hardware installation sequence on page 7
for procedures you should follow before and after installing or replacing hardware.
WARNING!You must remove the left side panel to access the system board. Before removing the
side access panel, ensure that the digital signage player is turned off and the power cord is
disconnected from the electrical outlet.
CAUTION:Static electricity can damage the electronic components of the computer or optional
cards. Before beginning these procedures, ensure that you are discharged of static electricity by
briefly touching a grounded metal object. When handling a memory module, be careful not to touch
any of the contacts. Doing so may damage the module.
To install the flash memory module:
1.Locate the correct flash memory module socket on the system board.
a.The PATA socket (1) is populated by default.
b.The SATA socket (2) can be populated with an optional SATA flash memory module.
Figure 2-12 Identifying the flash memory module sockets
16Chapter 2 Hardware changes
2.Align the connector on the flash memory module with the socket on the system board and press
the flash memory module into the socket.
NOTE:A flash memory module can be installed in only one way. Line up the hole in the flash
memory module with the retention post on the system board.
Figure 2-13 Inserting the flash memory module
3.Press the module connectors firmly into the flash memory module socket (1), making sure that
the retention post on the system board is aligned with the hole in the module.
Figure 2-14 Securing the flash memory module
4.Insert the screw (2) provided in the flash memory module option kit through the hole in the
module into the retention post and tighten to secure the module.
Installing digital signage player options17
Installing external drives
Various external USB drives are available as options for the MP4 Digital Signage Players. For more
information about these drives, visit
12454-12454-321959.html, or refer to the instructions that accompany the option.
http://h10010.www1.hp.com/wwpc/us/en/sm/WF12a/
For more information about available options, visit the HP website at
wwpc/us/en/sm/WF12a/12454-12454-321959.html.
http://h10010.www1.hp.com/
18Chapter 2 Hardware changes
ASpecifications
Table A-1 HP MP4 Digital Signage Player
Dimensions
Width (front to back)
Height (top to bottom, without stand)
Depth (side to side)
Approximate Weight1.53 kg3.37 lb
Temperature Range (fanless design)*
Operating**
(max. rate of change is 10° C per hour or 18° F per hour)
Nonoperating
(max. rate of change is 20° C per hour or 36° F per hour)
220 mm
240 mm
40 mm
10° to 40° C
-30° to 60° C
8.66 in.
9.45 in
1.57 in.
50° to 104° F
-22° to 140° F
*Specifications are at sea level with altitude derating of
1° C/300m (1.8° F/1000ft) to a maximum of 3km
(10,000ft), with no direct, sustained sunlight. Upper limit
may be limited by the type and number of options
installed.
Relative Humidity (non-condensing)
Operating
(max. wet bulb temperature is 28° C or 84.2° F)
Nonoperating
(max. wet bulb temperature is 38.7° C or 101.6° F)
Maximum Altitude (unpressurized)
Operating
(max. allowed rate of change is 457 m per minute or 1500
ft per minute)
Nonoperating
(max. allowed rate of change is 457 m per minute or 1500
ft per minute)
Power Supply
Operating Input Voltage Range
Rated Line Frequency
** The operating temperature range when the digital
signage player is attached to a flat panel using the HP
Quick Release is 50° to 95° F (10° to 35° C).
10–90%
5–95%
3048 m
9,144 m
100–240 VAC
50–60 Hz
10–90%
5–95%
10,000 ft
30,000 ft
100–240 VAC
50–60 Hz
Power Output (maximum)65 W65 W
Rated Output Current (maximum)3.33 A3.33 A
Output Voltage+19.5 V DC+19.5 V DC
19
BSecurity provisions
Securing the digital signage player
The HP MP4 Digital Signage Players are designed to accept a security cable lock. This cable lock
prevents unauthorized removal of the digital signage player, as well as locking the case. To order this
option, visit the HP website at
sku=2563044&pagemode=ca.
1.Locate the cable lock slot on the back panel.
2.Insert the cable lock into the slot, and then use the key to lock it.
Figure B-1 Securing the digital signage player
http://h30094.www3.hp.com/product.asp?
20Appendix B Security provisions
CMounting the digital signage player
HP Quick Release
The HP MP4 Digital Signage Players incorporate four mounting points on one side of the unit. These
mounting points follow the VESA (Video Electronics Standards Association) standard, which provides
industry-standard mounting interfaces for Flat Displays (FDs), such as flat panel monitors, flat
displays, and flat TVs. The HP Quick Release connects to the VESA-standard mounting points,
allowing you to mount the digital signage player in a variety of orientations.
NOTE:When mounting to a digital signage player, use the 15 mm screws supplied with the Quick
Release Kit.
Figure C-1 HP Quick Release
To order this option, visit the HP website at http://h10010.www1.hp.com/wwpc/us/en/sm/WF06c/
To use the HP Quick Release with a VESA-configured digital signage player:
1.Using four 15 mm screws included in the mounting device kit, attach one side of the HP Quick
Release to the digital signage player as shown in the following illustration.
Figure C-2 Connecting the HP Quick Release to the digital signage player
2.Using four screws included in the mounting device kit, attach the other side of the HP Quick
Release to the device to which you will mount the digital signage player. Make sure the release
lever points upward.
Figure C-3 Connecting the HP Quick Release to another device
22Appendix C Mounting the digital signage player
3.Slide the side of the mounting device attached to the digital signage player (1) over the other
side of the mounting device (2) on the device on which you want to mount the digital signage
player. An audible 'click' indicates a secure connection.
Figure C-4 Connecting the digital signage player
NOTE:When attached, the HP Quick Release automatically locks in position. You only need to
slide the lever to one side to remove the digital signage player.
CAUTION:To ensure proper function of the HP Quick Release and a secure connection of all
components, make sure both the release lever on one side of the mounting device and the rounded
opening on the other side face upward.
Supported mounting options
The following illustrations demonstrate some of the supported mounting options for the mounting
bracket.
You can mount the digital signage player on the back of a flat panel monitor.
●
You can mount the digital signage player on a wall.
●
Figure C-5 Digital signage player mounted on wall
You can mount the digital signage player under a desk with at least one inch of clearance.
●
Supported mounting options23
Figure C-6 Digital signage player mounted under desk
24Appendix C Mounting the digital signage player
DDigital signage player operation
Routine digital signage player care
Use the following information to properly care for your digital signage player:
Never operate the digital signage player with the outside panel removed.
●
Keep the digital signage player away from excessive moisture, direct sunlight, and extreme heat
●
and cold. For information about the recommended temperature and humidity ranges for the
digital signage player, see
●Keep liquids away from the digital signage player and keyboard.
Turn off the digital signage player and wipe the exterior with a soft, damp cloth as needed. Using
●
cleaning products may discolor or damage the finish.
Supported orientations
HP supports the following orientations for the digital signage player.
CAUTION:You must adhere to HP-supported orientations to ensure digital signage players function
properly.
Specifications on page 19.
You can place the digital signage player vertically using the supplied stand.
●
Figure D-1 Vertical orientation
You can lay the digital signage player horizontally on its rubber feet.
●
Routine digital signage player care25
Figure D-2 Horizontal orientation
●You can lay the digital signage player under a monitor stand with at least one inch of clearance.
Figure D-3 Under monitor stand
26Appendix D Digital signage player operation
Non-supported orientation
HP does not support the following orientation for the digital signage player.
CAUTION:Non-supported placement of digital signage players could result in operation failure and/
or damage to the devices.
CAUTION:Digital signage players require proper ventilation to maintain operating temperature. Do
not block the vents.
Do not put digital signage players in drawers or other sealed enclosures. Do not place a monitor or
other object on top of the digital signage player. Digital signage players require proper ventilation to
maintain operating temperatures.
Figure D-4 Do not put digital signage players in drawers or other sealed enclosures
Figure D-5 Do not place a monitor on the digital signage player
Non-supported orientation27
EElectrostatic discharge
A discharge of static electricity from a finger or other conductor may damage system boards or other
static-sensitive devices. This type of damage may reduce the life expectancy of the device.
Preventing electrostatic damage
To prevent electrostatic damage, observe the following precautions:
Avoid hand contact by transporting and storing products in static-safe containers.
●
Keep electrostatic-sensitive parts in their containers until they arrive at static-free workstations.
●
Place parts on a grounded surface before removing them from their containers.
●
Avoid touching pins, leads, or circuitry.
●
Always be properly grounded when touching a static-sensitive component or assembly.
●
Grounding methods
There are several methods for grounding. Use one or more of the following methods when handling
or installing electrostatic-sensitive parts:
Use a wrist strap connected by a ground cord to a grounded digital signage player chassis. Wrist
●
straps are flexible straps of 1 megohm +/- 10 percent resistance in the ground cords. To provide
proper grounding, wear the strap snug against the skin.
Use heelstraps, toestraps, or bootstraps at standing workstations. Wear the straps on both feet
●
when standing on conductive floors or dissipating floor mats.
Use conductive field service tools.
●
Use a portable field service kit with a folding static-dissipating work mat.
●
If you do not have any of the suggested equipment for proper grounding, contact an HP authorized
dealer, reseller, or service provider.
NOTE:For more information about static electricity, contact an HP authorized dealer, reseller, or
service provider.
28Appendix E Electrostatic discharge
FShipping information
Shipping preparation
Follow these suggestions when preparing to ship the digital signage player:
1.Turn off the digital signage player and external devices.
2.Disconnect the power cord from the electrical outlet, then from the digital signage player.
3.Disconnect the system components and external devices from their power sources, then from
the digital signage player.
4.Pack the system components and external devices in their original packing boxes or similar
packaging with sufficient packing material to protect them.
NOTE:For environmental nonoperating ranges, see Specifications on page 19.
Important service repair information
In all cases, remove and safeguard all external options before returning the digital signage player to
HP for repair or exchange.
In countries that support customer mail-in repair by returning the same unit to the customer, HP
makes every effort to return the repaired unit with the same internal memory and flash modules that
were sent.
In countries that do not support customer mail-in repair by returning the same unit to the customer, all
internal options should be removed and safeguarded in addition to the external options. The digital
signage player digital signage player should be restored to the original configuration before
returning it to HP for repair.
Shipping preparation29
Index
A
access panel
removing8
replacing10
altitude specifications19
B
battery, replacing11
C
cable lock, installing20
cautions
digital signage player
orientation25, 27
HP Quick Release23
static electricity7
ventilation27
microphone connector location1
mounting digital signage player
21
mounting options
on back of monitor23
on wall23
under desk23
N
non-supported orientations
in a drawer27
under a monitor27
O
options12
installing7
supported7
P
power button location1
power connector location2
power cord retention slot4
power LED location1
power output specifications19
power supply specifications19
preventing electrostatic damage