HP EliteDesk 800 G4 Maintenance and Service Guide - Page 17

Routine care, SATA drive guidelines, and disassembly preparation, Electrostatic discharge information

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3 Routine care, SATA drive guidelines, and disassembly preparation This chapter provides general service information for the computer. Adherence to the procedures and precautions described in this chapter is essential for proper service. CAUTION: When the computer is plugged into an AC power source, voltage is always applied to the system board. You must disconnect the power cord from the power source before opening the computer to prevent system board or component damage. 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% 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 Removing DIPs from vinyl tray Removing DIPs from Styrofoam Removing bubble pack from PCB Packing PCBs in foam-lined box 2,000 V 3,500 V 7,000 V 5,000 V These are then multi-packaged inside plastic tubes, trays, or Styrofoam. 40% 15,000 V 5,000 V 800 V 700 V 4,000 V 5,000 V 20,000 V 11,000 V 10% 35,000 V 12,000 V 6,000 V 2,000 V 11,500 V 14,500 V 26,500 V 21,000 V NOTE: 700 volts can degrade a product. Electrostatic discharge information 9

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3
Routine care, SATA drive guidelines, and
disassembly preparation
This chapter provides general service information for the computer. Adherence to the procedures and
precautions described in this chapter is essential for proper service.
CAUTION:
When the computer is plugged into an AC power source, voltage is always applied to the system
board. You must disconnect the power cord from the power source before opening the computer to prevent
system board or component damage.
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
Removing DIPs from vinyl tray
Removing DIPs from Styrofoam
Removing bubble pack from PCB
Packing PCBs in foam-lined box
2,000 V
3,500 V
7,000 V
5,000 V
4,000 V
5,000 V
20,000 V
11,000 V
11,500 V
14,500 V
26,500 V
21,000 V
These are then multi-packaged inside plastic tubes, trays, or Styrofoam.
NOTE:
700 volts can degrade a product.
Electrostatic discharge information
9