4 Removal and replacement procedures preliminary requirements
Use this information to properly prepare to disassemble and reassemble the computer.
Tools required
You need the following tools to complete the removal and replacement procedures:
● Tweezers
● Nonconductive, nonmarking pry tool
● Magnetic Phillips P1 screwdriver
Service considerations
The following sections include some of the considerations that you must keep in mind during disassembly and assembly procedures.
NOTE: As you remove each subassembly from the computer, place the subassembly (and all accompanying screws) away from the work area to prevent damage.
Plastic parts
Using excessive force during disassembly and reassembly can damage plastic parts.
Cables and connectors
Handle cables with extreme care to avoid damage.
IMPORTANT: When servicing the computer, be sure that cables are placed in their proper locations during the reassembly process. Improper cable placement can damage the computer.
Apply only the tension required to unseat or seat the cables during removal and insertion. Handle cables by the connector whenever possible. In all cases, avoid bending, twisting, or tearing cables. Be sure that cables are routed so that they cannot be caught or snagged as you remove or replace parts. Handle flex cables with extreme care; these cables tear easily.
Drive handling
Note the following guidelines when handling drives.
28 Chapter 4 Removal and replacement procedures preliminary requirements
IMPORTANT: Drives are fragile components. Handle them with care. To prevent damage to the computer, damage to a drive, or loss of information, observe these precautions:
Before removing or inserting a hard drive, shut down 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.
Before handling a drive, be sure that you are discharged of static electricity. While handling a drive, avoid touching the connector.
Handle drives on surfaces covered with at least 2.54 cm (1 inch) of shock-proof foam.
Avoid dropping drives from any height onto any surface.
After removing a hard drive or an optical drive, place it in a static-proof bag.
Avoid exposing an internal hard drive to products that have magnetic fields, such as monitors or speakers.
Avoid exposing a drive to temperature extremes or liquids.
If a drive must be mailed, place the drive in a bubble pack mailer or other suitable form of protective packaging, and label the package “FRAGILE.”
Workstation guidelines
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 equipment.
● 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-safe materials.
● Keep the work area free of nonconductive materials, such as ordinary plastic assembly aids and polystyrene foam.
● 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.
Electrostatic discharge information
A sudden discharge of static electricity from your finger or other conductor can destroy static-sensitive devices or microcircuitry. Often the spark is neither felt nor heard, but damage occurs. An electronic device exposed to electrostatic discharge (ESD) might not appear to be affected at all and can work perfectly throughout a normal cycle. The device might function normally for a while, but it has been degraded in the internal layers, reducing its life expectancy.
Networks built into many integrated circuits provide some protection, but in many cases, the discharge contains enough power to alter device parameters or melt silicon junctions.
Electrostatic discharge information 29
IMPORTANT: To prevent damage to the device when you remove or install 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
Personal grounding methods and equipment on page 31 .
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.
Generating static electricity
Follow these static electricity guidelines.
● Different activities generate different amounts of static electricity.
● Static electricity increases as humidity decreases.
Table 4-1 Static electricity occurrence based on activity and humidity
Event
Walking across carpet
Walking across vinyl floor
Motions of bench worker
Removing DIPs (dual in-line packages) from plastic tube
Removing DIPs from vinyl tray
Removing DIPs from polystyrene foam
Removing bubble pack from PCB (printed circuit board)
Packing PCBs in foam-lined box
55%
7,500 V
3,000 V
400 V
400 V
2,000 V
3,500 V
7,000 V
5,000 V
Relative humidity
Multiple electric components can be packaged together in plastic tubes, trays, or polystyrene foam.
40%
15,000 V
5,000 V
800 V
700 V
4,000 V
5,000 V
20,000 V
11,000 V
10%
35,000 V
12,000 V
6,000 V
2,000 V
11,500 V
14,500 V
26,500 V
21,000 V
NOTE: As little as 700 V can degrade a product.
Preventing electrostatic damage to equipment
Many electronic components are sensitive to ESD. Circuitry design and structure determine the degree of sensitivity. The following packaging and grounding precautions are necessary to prevent static electricity damage to electronic components.
● To avoid hand contact, transport products in static-safe containers such as tubes, bags, or boxes.
● Protect all electrostatic parts and assemblies with conductive or approved containers or packaging.
● Keep electrostatic-sensitive parts in their containers until they arrive at static-free stations.
● Place items on a grounded surface before removing them from their container.
● Always be properly grounded when touching a sensitive component or assembly.
30 Chapter 4 Removal and replacement procedures preliminary requirements
● Avoid contact with pins, leads, or circuitry.
● Place reusable electrostatic-sensitive parts from assemblies in protective packaging or conductive foam.
Personal grounding methods and equipment
Using certain equipment can prevent static electricity damage to electronic components.
● Wrist straps are flexible straps with a maximum of 1 MΩ ±10% resistance in the ground cords. To provide proper ground, a strap must be worn snug against bare skin. The ground cord must be connected and fit snugly into the banana plug connector on the grounding mat or workstation.
● Heel straps/Toe straps/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 them on both feet with a maximum of 1 MΩ ±10% resistance between the operator and ground.
Table 4-2 Static shielding protection levels
Static shielding protection levels
Method
Antistatic plastic
Carbon-loaded plastic
Metallized laminate
Voltage
1,500
7,500
15,000
Grounding the work area
To prevent static damage at the work area, follow these precautions.
● Cover the work surface with approved static-dissipative material. Provide a wrist strap connected to the work surface and properly grounded tools and equipment.
● Use static-dissipative mats, foot straps, or air ionizers to give added protection.
● Handle electrostatic sensitive components, parts, and assemblies by the case or PCB laminate. Handle them only at static-free work areas.
● Turn off power and input signals before inserting and removing connectors or test equipment.
● Use fixtures made of static-safe materials when fixtures must directly contact dissipative surfaces.
● Keep work area free of nonconductive materials such as ordinary plastic assembly aids and polystyrene foam.
● Use field service tools, such as cutters, screwdrivers, and vacuums, that are conductive.
Recommended materials and equipment
HP recommends certain materials and equipment to prevent static electricity.
● Antistatic tape
● Antistatic smocks, aprons, or sleeve protectors
● Conductive bins and other assembly or soldering aids
● Conductive foam
● Conductive tabletop workstations with ground cord of 1 MΩ ±10% resistance
Electrostatic discharge information 31
● Static-dissipative table or floor mats with hard tie to ground
● Field service kits
● Static awareness labels
● Wrist straps and footwear straps providing 1 MΩ ±10% resistance
● Material handling packages
● Conductive plastic bags
● Conductive plastic tubes
● Conductive tote boxes
● Opaque shielding bags
● Transparent metallized shielding bags
● Transparent shielding tubes
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.
32 Chapter 4 Removal and replacement procedures preliminary requirements
