HP Xw8400 HP xw8400 Service and Technical Reference Guide - Page 60

Service considerations The following sections discuss service considerations that should be reviewed and practiced before removing and replacing any system components. WARNING! When lifting or moving the workstation, do not use the front bezel as a handle or lifting point. Lifting the workstation from the front bezel or lifting it incorrectly can cause the unit to fall and harm the user and damage the workstation. To properly and safely lift the workstation, lift it from the bottom of the unit. Read cautions, warnings, and safety precautions For your safety, you must review all safety warning and caution notices before accessing the components of the workstation. Also, review the Safety and Regulatory Guide that came with your workstation for more information. WARNING! Some parts inside the computer will be hot. Power off and unplug the system, and then wait approximately three to five minutes for them to cool before opening the system access panels or touching internal components. Electrostatic discharge information A sudden discharge of static electricity from your 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) might not appear to be affected at all and can work perfectly throughout a normal cycle. The device can function normally for a while, but it has been degraded 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 following table shows that Different activities generate different amounts of static electricity. Static electricity increases as humidity decreases. Table 4-1 Static electricity Event Walking across carpet Walking across vinyl floor Motions of bench worker Removing bubble pack from PCB Packing PCBs in foam-lined box 5% 7,500 V 3,000 V 400 V 7,000 V 5,000 V Relative Humidity 4% 1% 15,000 V 35,000 V 5,000 V 12,000 V 800 V 6,000 V 20,000 V 26,500 V 11,000 V 21,000 V CAUTION 700 volts can degrade a product. 50 Chapter 4 Removal and replacement procedures ENWW