HP dx7510 Service Reference Guide: HP Compaq dx7510/dx7518 Business PC - Page 32

Electrostatic Discharge Information, Generating Static - compaq

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Figure 5-2 HP Compaq dx7518 Microtower NOTE: The appearance of the front bezel may vary. 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) may not appear to be affected at all and can work perfectly throughout a normal cycle. The device may 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. Event Walking across carpet Walking across vinyl floor Motions of bench worker Removing DIPs* from plastic tube 55% 7,500 V 3,000 V 400 V 400 V Relative Humidity 40% 15,000 V 5,000 V 800 V 700 V 10% 35,000 V 12,000 V 6,000 V 2,000 V 24 Chapter 5 Identifying the Chassis, Routine Care, and Disassembly Preparation

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Figure 5-2
HP Compaq dx7518 Microtower
NOTE:
The appearance of the front bezel may vary.
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) may not appear to be affected at all and can work
perfectly throughout a normal cycle. The device may 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.
Relative Humidity
Event
55%
40%
10%
Walking across carpet
Walking across vinyl floor
Motions of bench worker
Removing DIPs* from plastic tube
7,500 V
3,000 V
400 V
400 V
15,000 V
5,000 V
800 V
700 V
35,000 V
12,000 V
6,000 V
2,000 V
24
Chapter 5
Identifying the Chassis, Routine Care, and Disassembly Preparation