Compaq 7470 - Presario - 64 MB RAM, Maintenance And Service Manual

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United States
Maintenance and Service Guide
Compaq Presario 7400 Series Computers
MSG index Product Description Troubleshooting Illustrated Parts Catalog
Home Removal & Replacement Jumper & Switch Information Specifications
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
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.
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
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