Compaq 1200US Presario Select 1200 Series Maintenance and Service Guide - Page 35

Maintenance & Service Guide Presario Series Models: 1246, 1247, 1277, 1278, and 1279 | Home Page | Notice | Preface | Product Description | Troubleshooting Illustrated Parts Catalog | Removal & Replacement Procedures | Specifications Pin Assignments | Battery Pack Operations 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% Walking across carpet 35,000 V 15,000 V Walking across vinyl floor 12,000 V 5,000 V Motions of bench worker 6,000 V 800 V Removing DIPS from plastic tubes 2,000 V 700 V Removing DIPS from vinyl trays 11,500 V 4,000 V Removing DIPS from Styrofoam 14,500 V 5,000 V Removing bubble pack from PCBs 26,000 V 20,000 V Packing PCBs in foam-lined box 21,000 V 11,000 V NOTE: 700 volts can degrade a product. 55% 7,500 V 3,000 V 400 V 400 V 2,000 V 3,500 V 7,000 V 5,000 V Return to Removal & Replacement Procedures