6. Remove any media card and optical disc from your computer, if applicable.
Safety precautions
This section details the primary steps to be followed before performing any disassembly instructions.
Observe the following safety precautions before you perform any installation or break-fix procedures involving disassembly or
reassembly:
● Turn off the computer and all attached peripherals.
● Disconnect the computer from AC power.
● Disconnect all network cables and peripherals from the computer.
● Use an ESD field service kit when working inside any desktop to avoid electrostatic discharge (ESD) damage.
● Place the removed component on an anti-static mat after removing it from the computer.
● Wear shoes with nonconductive rubber soles to reduce the chance of getting electrocuted.
● Unplugging, pressing, and holding the power button for 15 seconds should discharge residual power in the system board.
Standby power
Dell products with standby power must be unplugged before you open the back cover. Systems that are equipped with standby
power are powered while turned off. The internal power enables the computer to be remotely turned on (Wake-on-LAN) and
suspended into a sleep mode and has other advanced power management features.
Bonding
Bonding is a method for connecting two or more grounding conductors to the same electrical potential. This is done by using a field
service electrostatic discharge (ESD) kit. When connecting a bonding wire, ensure that it is connected to bare metal and never to
a painted or nonmetal surface. Ensure that the wrist strap is secure and in full contact with your skin. Remove all jewelry, watches,
bracelets, or rings before grounding yourself and the equipment.
Electrostatic discharge—ESD protection
ESD is a major concern when you handle electronic components, especially sensitive components such as expansion cards, processors,
memory modules, and system boards. A slight charge can damage circuits in ways that may not be obvious, such as intermittent
problems or a shortened product life span. As the industry pushes for lower power requirements and increased density, ESD
protection is an increasing concern.
Two recognized types of ESD damage are catastrophic and intermittent failures.
● Catastrophic – Catastrophic failures represent approximately 20 percent of ESD-related failures. The damage causes an
immediate and complete loss of device functionality. An example of catastrophic failure is a memory module that has received
a static shock and immediately generates a "No POST/No Video" symptom with a beep code that is emitted for missing or
nonfunctional memory.
● Intermittent – Intermittent failures represent approximately 80 percent of ESD-related failures. The high rate of intermittent
failures means that most of the time when damage occurs, it is not immediately recognizable. The memory module receives
a static shock, but the tracing is merely weakened and does not immediately produce outward symptoms that are related to
the damage. The weakened trace may take weeks or months to melt, and in the meantime may cause degradation of memory
integrity, intermittent memory errors, and so on.
Intermittent failures that are also called latent or "walking wounded" are difficult to detect and troubleshoot.
Perform the following steps to prevent ESD damage:
● Use a wired ESD wrist strap that is properly grounded. Wireless anti-static straps do not provide adequate protection. Touching
the chassis before handling parts does not ensure adequate ESD protection on parts with increased sensitivity to ESD damage.
● Handle all static-sensitive components in a static-safe area. If possible, use anti-static floor pads and workbench pads.
● When unpacking a static-sensitive component from its shipping carton, do not remove the component from the anti-static
packing material until you are ready to install the component. Before unwrapping the anti-static packaging, use the anti-static
wrist strap to discharge the static electricity from your body. For more information about the wrist strap and ESD wrist strap
tester, see
Components of an ESD Field Service Kit.
● Before transporting a static-sensitive component, place it in an anti-static container or packaging.
30 Working inside your computer
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