Dell OptiPlex 3090 Ultra, Service Manual, Page: 6 / 140

Working on your computer
Topics:
• Safety instructions
Safety instructions
Use the following safety guidelines to protect your computer from potential damage and to ensure your personal safety. Unless
otherwise noted, each procedure included in this document assumes that you have read the safety information that shipped
with your computer.
WARNING: Before working inside your computer, read the safety information that is shipped with your
computer. For more safety best practices, see the Regulatory Compliance home page at www.dell.com/
regulatory_compliance .
WARNING: Disconnect your computer from all power sources before opening the computer cover or panels.
After you finish working inside the computer, replace all covers, panels, and screws before connecting your
computer to an electrical outlet.
CAUTION: To avoid damaging the computer, ensure that the work surface is flat, dry, and clean.
CAUTION: To avoid damaging the components and cards, handle them by their edges, and avoid touching the
pins and the contacts.
CAUTION: You should only perform troubleshooting and repairs as authorized or directed by the Dell technical
assistance team. Damage due to servicing that is not authorized by Dell is not covered by your warranty. See the
safety instructions that is shipped with the product or at
www.dell.com/regulatory_compliance .
CAUTION: Before touching anything inside your computer, ground yourself by touching an unpainted metal
surface, such as the metal at the back of the computer. While you work, periodically touch an unpainted metal
surface to dissipate static electricity which could harm internal components.
CAUTION: When you disconnect a cable, pull it by its connector or its pull tab, not the cable itself. Some cables
have connectors with locking tabs or thumbscrews that you must disengage before disconnecting the cable.
When disconnecting cables, keep them evenly aligned to avoid bending the connector pins. When connecting
cables, ensure that the ports and the connectors are correctly oriented and aligned.
CAUTION: Press and eject any installed card from the media-card reader.
CAUTION: Exercise caution when handling Lithium-ion batteries in laptops. Swollen batteries should not be used
and should be replaced and disposed properly.
NOTE: The color of your computer and certain components may appear differently than shown in this document.
Before working inside your device
About this task
To avoid damaging your device, perform the following steps before you begin working inside the device:
Steps
1. Ensure that you follow the Safety Instruction .
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6 Working on your computer