United States

Maintenance & Service Guide
Presario Series
Models: 1246, 1247, 1277, 1278, and 1279

Removal and Replacement Procedures

Electrostatic Discharge

CAUTION: 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. The device may function normally for a while, then degrade in the internal layers. This reduces the device's life expectancy.

Networks built into many integrated circuits provide some protection from discharges of static electricity, but in many cases the discharge contains enough power to alter device parameters or melt silicon junctions.

Generating Static

The following table shows how different activities generate static electricity at different electrostatic voltage levels.

Typical Electrostatic Voltages
	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
Removing DIPS from vinyl trays	11,500 V	4,000 V	2,000 V
Removing DIPS from Styrofoam	14,500 V	5,000 V	3,500 V
Removing bubble pack from PCBs	26,000 V	20,000 V	7,000 V
Packing PCBs in foam-lined box	21,000 V	11,000 V	5,000 V
NOTE: 700 volts can degrade a product.

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