HP Business Desktop dx5150 Series Service Reference Guide, 1st Edition

Service Reference Guide, dx5150 361685-001 5–3
Identifying the Chassis, Routine Care, and Disassembly Preparation
5.2.1 Generating Static
The following table shows that:
■ Different activities generate different amounts of static electricity.
■ Static electricity increases as humidity decreases.
✎
700 volts can degrade a product.
5.2.2 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 damage to electric components and accessories.
■ 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.
■ Avoid contact with pins, leads, or circuitry.
■ Place reusable electrostatic-sensitive parts from assemblies in protective packaging or
conductive foam.
5.2.3 Personal Grounding Methods and Equipment
Use the following equipment to prevent static electricity damage to equipment:
■ Wrist straps are flexible straps with a maximum of one-megohm ± 10% resistance in the
ground cords. To provide proper ground, you must wear a strap snug against bare skin. The
ground cord must be connected and fit snugly into the banana plug connector on the
grounding mat or workstation.
Relative Humidity
Event 55% 40% 10%
Walking across carpet
Walking across vinyl floor
Motions of bench worker
Removing DIPs* from plastic tube
7, 5 0 0 V
3,000 V
400 V
400 V
15,000 V
5,000 V
800 V
700 V
35,000 V
12,000 V
6,000 V
2,000 V
Removing DIPs* from vinyl tray
Removing DIPs* from Styrofoam
Removing bubble pack from PCB
Packing PCBs in foam-lined box
2,000 V
3,500 V
7,000 V
5,000 V
4,000 V
5,000 V
20,000 V
11,000 V
11,500 V
14,500 V
26,500 V
21,000 V
*These components are multi-packaged inside plastic tubes, trays, or Styrofoam.