Routine Care, Sata Drive Guidelines, And Disassembly Preparation; Electrostatic Discharge Information; Generating Static Electricity - HP 280 G4 Maintenance And Service Manual

3 Routine care, SATA drive guidelines, and
disassembly preparation
This chapter provides general service information for the computer. Adherence to the procedures and
precautions described in this chapter is essential for proper service.
IMPORTANT:
system board. You must disconnect the power cord from the power source before opening the computer to
prevent system board or component damage.

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.
IMPORTANT:
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
section.
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

The following table shows how humidity affects the electrostatic voltage levels generated by different
activities. A product can be degraded by 700 V.
● Different activities generate different amounts of static electricity.
Static electricity increases as humidity decreases.
●
Table 3-1 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
8 Chapter 3 Routine care, SATA drive guidelines, and disassembly preparation
When the computer is plugged into an AC power source, voltage is always applied to the
To prevent damage to the device when you are removing or installing internal components,
Relative humidity
55% 40%
7,500 V 15,000 V
3,000 V 5,000 V
400 V 800 V
400 V 700 V
10%
35,000 V
12,000 V
6,000 V
2,000 V