Electrostatic Discharge Information; Generating Static - HP Compaq d220 MT Reference Manual

Identifying the Chassis, Routine Care, and Disassembly Preparation
Chassis Characteristic
Power supply mounting
method
Power supply installation
method
Lower drive cage retaining
screws
Processor cooling method
Memory
Number of memory sockets

5.2 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.

5.2.1 Generating Static

The following table shows that:
■
Different activities generate different amounts of static electricity.
■
Static electricity increases as humidity decreases.
Walking across carpet
Walking across vinyl floor
Motions of bench worker
Removing bubble pack from PCB
Packing PCBs in foam-lined box
✎
700 volts can degrade a product.
5–2
Microtower Type 2 Chassis Variations
d220, d228, d230
Removable power supply
support bracket
Lay chassis on its side for
easiest installation
Four screws on front of chassis
plus one on the side
Air baffle
Single channel
2
Event
336493-004
d240, d248
No support bracket required
Keep chassis in upright
position for easiest installation
Three screws on front of
chassis plus one on the side
Chassis fan
Dual channel
4
Relative Humidity
55% 40%
7,500 V 15,000 V
3,000 V 5,000 V
400 V 800 V
7,000 V 20,000 V
5,000 V 11,000 V
Service Reference Guide, d200
10%
35,000 V
12,000 V
6,000 V
26,500 V
21,000 V