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CAUTION:To prevent damage to the computer when you are removing or installing internal components,
observe these precautions:
Keep components in their electrostatic-safe containers until you are ready to install them.
Before touching an electronic component, discharge static electricity by using the guidelines described in this
Avoid touching pins, leads, and circuitry. Handle electronic components as little as possible.
If you remove a component, place it in an electrostatic-safe container.
The following table shows how humidity affects the electrostatic voltage levels generated by
CAUTION:A product can be degraded by as little as 700 V.
Typical electrostatic voltage levels
Event 10% 40% 55%
Walking across carpet 35,000 V 15,000 V 7,500 V
Walking across vinyl floor 12,000 V 5,000 V 3,000 V
Motions of bench worker 6,000 V 800 V 400 V
Removing DIPS from plastic tube 2,000 V 700 V 400 V
Removing DIPS from vinyl tray 11,500 V 4,000 V 2,000 V
Removing DIPS from Styrofoam 14,500 V 5,000 V 3,500 V
Removing bubble pack from PCB 26,500 V 20,000 V 7,000 V
Packing PCBs in foam-lined box 21,000 V 11,000 V 5,000 V
Grounding guidelines 43
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Packaging and transporting guidelines
Follow these grounding guidelines when packaging and transporting equipment:
To avoid hand contact, transport products in static-safe tubes, bags, or boxes.
Protect ESD-sensitive parts and assemblies with conductive or approved containers or packaging.
Keep ESD-sensitive parts in their containers until the parts arrive at static-free workstations.
Place items on a grounded surface before removing items from their containers.
Always be properly grounded when touching a component or assembly.
Store reusable ESD-sensitive parts from assemblies in protective packaging or nonconductive foam.
Use transporters and conveyors made of antistatic belts and roller bushings. Be sure that mechanized
equipment used for moving materials is wired to ground and that proper materials are selected to avoid
static charging. When grounding is not possible, use an ionizer to dissipate electric charges.
Follow these grounding workstation guidelines:
Cover the workstation with approved static-shielding material.
Use a wrist strap connected to a properly grounded work surface and use properly grounded tools and
Use conductive field service tools, such as cutters, screw drivers, and vacuums.
When fixtures must directly contact dissipative surfaces, use fixtures made only of static-
Keep the work area free of nonconductive materials, such as ordinary plastic assembly aids
Handle ESD-sensitive components, parts, and assemblies by the case or PCM laminate. Handle these
items only at static-free workstations.
Avoid contact with pins, leads, or circuitry.
Turn off power and input signals before inserting or removing connectors or test equipment.
44 Chapter 4 Removal and replacement preliminary requirements
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Grounding equipment must include either a wrist strap or a foot strap at a grounded workstation.
When seated, wear a wrist strap connected to a grounded system. Wrist straps are flexible straps with a
minimum of one megohm ±10% resistance in the ground cords. To provide proper ground, wear a strap
snugly against the skin at all times. On grounded mats with banana-plug connectors, use alligator clips
to connect a wrist strap.
When standing, use foot straps and a grounded floor mat. Foot straps (heel, toe, or boot straps) can be
used at standing workstations and are compatible with most types of shoes or boots. On conductive
floors or dissipative floor mats, use foot straps on both feet with a minimum of one megohm resistance
between the operator and ground. To be effective, the conductive must be worn in contact with the
The following grounding equipment is recommended to prevent electrostatic damage:
Antistatic smocks, aprons, and sleeve protectors
Conductive bins and other assembly or soldering aids
Conductive computerop workstations with ground cords of one megohm resistance
Static-dissipative tables or floor mats with hard ties to the ground
Field service kits
Static awareness labels
Nonconductive plastic bags, tubes, or boxes
Metal tote boxes
Electrostatic voltage levels and protective materials
The following table lists the shielding protection provided by antistatic bags and floor mats.
Material Use Voltage protection level
Antistatic plastics Bags 1,500 V
Carbon-loaded plastic Floor mats 7,500 V
Metallized laminate Floor mats 5,000 V
Grounding guidelines 45
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5 Removal and replacement procedures for
Customer Self-Repair parts
NOTE:The Customer Self-Repair program is not available in all locations. Installing a part not supported by
the Customer Self-Repair program may void your warranty. Check your warranty to determine if Customer
Self-Repair is supported in your location.
NOTE:HP continually improves and changes product parts. For complete and current information on
supported parts for your computer, go to
http://partsurfer.hp.com, select your country or region, and then
follow the on-screen instructions.
Component replacement procedures
This chapter provides removal and replacement procedures for Authorized Service Provider only parts.
There are as many as 15 screws that must be removed, replaced, and/or loosened when servicing the
computer. Make special note of each screw size and location during removal and replacement.
NOTE:The service cover spare part kit includes rubber feet.
DescriptionSpare part number
Service cover for use in 820 G2 models 781836-001
Service cover for use in 720 G2 models 790080-001
Service cover for use only on RCTO models 797517-001
Before removing the disassembling the computer, follow these steps:
1.Turn off the computer. If you are unsure whether the computer is off or in Hibernation, turn the
computer on, and then shut it down through the operating system.
2.Disconnect the power from the computer by unplugging the power cord from the computer.
3.Disconnect all external devices from the computer.
Remove the service cover:
1.Turn the computer upside down, with the rear toward you.
2.Slide the service cover release latch (1) to gain access to the service cover security screw.
3.Remove the Phillips PM2.0×4.5 security screw (2) (if present).
NOTE:The service cover includes a threaded receptacle for storing the security screw.
4.Slide the service cover release latch a second time (3) to release the service cover.
5.Release the service cover (4) by sliding it forward.
46 Chapter 5 Removal and replacement procedures for Customer Self-Repair parts
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6.Remove the service cover (5).
Reverse this procedure to install the service cover.
Component replacement procedures 47