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This chapter
provides general service information for Compaq Presario 5800 Series Personal Computers.
Adherence to the procedures and precautions described in this chapter is essential for
proper service.
The topics discussed in this section include
the following:
A sudden discharge of static electricity
from a 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) may not be affected at all and will work perfectly
throughout a normal cycle. Or it may function normally for a while, then degrade 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.
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The accompanying table shows typical
electrostatic voltages generated by different activities.
Typical Electrostatic Voltages |
|
Relative
Humidity |
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
tubes |
2,000 V |
700 V |
400 V |
Removing DIPS from vinyl trays |
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 PCBs |
26,000 V |
20,000 V |
7,000 V |
Packing PCBs in foam-lined box |
21,000 V |
11,000 V |
5,000 V |
NOTE: 700
volts can degrade a product. |
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Many electronic components are sensitive to
ESD. Circuitry design and structure determine the degree of sensitivity. The following
proper packaging and grounding precautions are necessary to prevent damage:
- 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.
- Place reusable electronic-sensitive parts from assemblies
in protective packaging or conductive foam.
- Use transporters and conveyors made of antistatic belts
and metal roller bushings. Mechanized equipment used for moving materials must be wired to
ground and proper materials selected to avoid static charging. When grounding is not
possible, use an ionizer to dissipate electric charges.
The accompanying table shows typical
static-shielding protection levels afforded by different protective packaging materials.
Static-Shielding Protection Levels |
Method |
Voltages |
Antistatic Plastic |
1,500 |
Carbon-Loaded Plastic |
7,500 |
Metallized Laminate |
15,000 |
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To prevent static damage to hard drives, use
the following precautions:
- Handle drives gently, using static-guarding techniques.
- Store drives in the original shipping containers.
- Avoid dropping drives from any height onto any surface.
- Handle drives on surfaces that have at least one inch of
shock-proof foam.
- Always place drives PCB assembly side down on the foam.
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The method for grounding must include a
wrist strap or a foot strap at a grounded workstation. When seated, wear a wrist strap
connected to a grounded system. When standing, use footstraps and a grounded floor mat.
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Grounding Workstations
To prevent static damage at the workstation,
use the following precautions:
- Cover the workstation with approved static-dissipative
material.
- Provide a wrist strap connected to the work surface and
properly grounded tools and equipment.
- Use static-dissipative mats, heel 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 workstations.
- Avoid contact with pins, leads, or circuitry.
- 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 Styrofoam.
- Use field service tools that are conductive, such as
cutters, screwdrivers, vacuums.
- Use a portable field service kit with a static-dissipative
vinyl pouch that folds out of a work mat. Also use a wrist strap and a ground cord for the
work surface. Ground the cord to the chassis of the equipment undergoing test or repair.
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Use the following equipment to prevent
static electricity damage to the equipment:
- Wrist straps are flexible straps with a minimum of 1 mega
ohm ± 10% resistance to the ground cords. To provide proper ground, a strap must
be worn snug against the skin. On grounded mats without banana-plug connectors, connect a
wrist strap with alligator clips.
- Heelstraps/Toestraps/Bootstraps can be used at standing
workstations and are compatible with most types of boots and shoes. On conductive floors
or dissipative floor mats, use them on both feet with a minimum of 1 mega ohm resistance
between operator and ground. To be effective, the conductive strips must be worn in
contact with the skin.
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Other materials and equipment that are
recommended for use in preventing static electricity include:
- 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
mega ohm
of resistance
- Static-dissipative table or floor mats with hard tie to
ground
- Field service kits
- Static awareness labels
- Wrist straps and footwear straps providing 1 mega ohm (±10%) resistance
- Material handling packages
- Conductive plastic bags
- Conductive plastic tubes
- Conductive tote boxes
- Metal tote boxes
- Opaque shielding bags
- Transparent metallized shielding bags
- Transparent shielding tubes
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- Torx T-8, T-10, and T-15 screwdrivers
- Needle-nose pliers
- Flat-blade screwdriver
- Diagnostics software
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The screws used in these products are not
interchangeable. If an incorrect screw is used during the reassembly process, it could
cause damage to the unit. Compaq strongly recommends that all screws removed during the
disassembly process be kept with the part that was removed, then returned to their proper
locations.
IMPORTANT: |
As each subassembly
is removed from the computer, it should be placed away from the work area to prevent
damage |
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Most cables used throughout the unit are
ribbon cables. These cables must be handled with extreme care to avoid damage.
Apply only the tension required to seat or
unseat the cables during insertion or removal from the connector. Handle cables by the
connector whenever possible. In all cases, avoid bending, twisting, or tearing the cables,
and ensure that cables are placed in such a way that they cannot be caught or snagged by
parts being removed or replaced.

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CAUTION: When
servicing these computers, ensure that cables are placed in their proper location during
the reassembly process. Improper cable placement can cause severe damage to the unit. |
CD or DVD Drive
Digital Creativity Imaging
Center
Diskette Drive
Hard Drive
Zip Drive
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