Compaq Presario 7400 Series Maintenance And Service Manual page 69

Compaq.com - Compaq Presario Maintenance and Service Guide - 7400 Series
Maintenance and Service Guide
Compaq Presario 7400 Series Computers
MSG index
Home Removal & Replacement
REMOVAL
SEQUENCE
Electrostatic
discharge
Service
considerations
Preparation for
disassembly
Serial number
Chassis
Power supply
Mass storage
devices
Fax-modem
Parallel port
assembly
PCI bracket
System board
Instant On button
board
http://www.compaq.com/athome/support/msgs/7400/electro.html (1 of 4) [1/8/2002 3:52:34 PM]
Product Description
REMOVAL & REPLACEMENT - BEFORE YOU BEGIN
Electrostatic Discharge
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 awhile and
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.
Generating Static
The table below shows the different amounts of static electricity generated by different activities.
Event
Walking across carpet
Walking across vinyl floor
Motions of bench worker
Removing DIPS from plastic tubes
Troubleshooting
Jumper & Switch Information
10%
35,000 V
12,000 V
6,000 V
2,000 V
United States
Illustrated Parts Catalog
Specifications
Relative Humidity
40% 55%
15,000 V
7,500 V
5,000 V
3,000 V
800 V
400 V
700 V
400 V