Compaq Presario 18XL Maintenance & Service Guide Presario 1800/1800T Serie - Page 70

Presario 1800/1800T Series Models: XL280, XL380, XL381, and XL390 Removal & Replacement This chapter details the necessary preparations for disassembling the Notebook and explains removing and replacing each component of the Presario 1800XL Series Notebooks. Electrostatic Discharge Ä CAUTION: When removing or replacing parts, be careful to discharge static electricity before touching the Notebook's internal components. A sudden discharge of static electricity from a finger or other conductor can destroy static-sensitive devices and microcircuitry. Often the spark is neither felt nor heard, but damage occurs. An electronic device exposed to an electrostatic discharge may work perfectly throughout a normal cycle. However, the discharge degrades internal layers, which reduces the operating life of the device. Networks built into many integrated circuits provide some protection, but in many cases the discharge still contains enough power to alter device parameters or melt silicon junctions. The table below shows the amount of static electricity generated by common activities associated with servicing computers. Generated Electrostatic Voltage Activity Walking across carpet Walking across vinyl floor Motions of bench worker Relative Humidity 10% 40% 55% 35,000 V 15,000 V 7,500 V 12,000 V 5,000 V 3,000 V 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 Ä CAUTION: As little as 700 Volts can degrade Notebook components. Be sure to ground yourself before touching the Notebook or its subassemblies. PRESARIO NOTEBOOK MAINTENANCE AND SERVICE GUIDE 1800 SERIES REMOVAL & REPLACEMENT 1