Service Considerations; Cautions, Warnings, And Safety Precautions; Electrostatic Discharge Information; Generating Static - HP xw4400 Service And Technical Reference Manual

Service considerations

The following sections discuss service considerations that should be reviewed and practiced before
removing and replacing any system components.
WARNING!
or lifting point. Lifting the workstation from the front bezel or lifting it incorrectly can cause the unit
to fall and harm you and damage the workstation. To properly and safely lift the workstation, lift
it from the bottom of the unit.

Cautions, warnings, and safety precautions

For your safety, review the cautions, warnings, and safety precautions before accessing the workstation
components. Also, review the Safety and Regulatory Guide that came with your workstation for more
information.

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 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.

Generating static

The following table shows that different activities generate different amounts of static electricity. Static
electricity increases as humidity decreases.
Table 4-1 Static electricity
Event
Walking across carpet
Walking across vinyl floor
Motions of bench worker
Removing bubble pack from PCB
Packing PCBs in foam-lined box
NOTE: 700 volts can degrade a product.
54 Chapter 4 Removal and replacement procedures
When lifting or moving the workstation, do not use the front bezel as a handle
Relative humidity
55% 40%
7,500 V 15,000 V
3,000 V 5,000 V
400 V 800 V
7,000 V 20,000 V
5,000 V 11,000 V
10%
35,000 V
12,000 V
6,000 V
26,500 V
21,000 V
ENWW