Cisco Systems AS5800 Rack-Mounting Considerations, Preventing Electrostatic Discharge Damage

Rack-Mounting Considerations

Preventing Electrostatic Discharge Damage

Electrostatic discharge (ESD) damage, which occurs when electronic cards or components are improperly handled, can result in complete or intermittent system failures. The access server components include printed circuit boards that are fixed in metal carriers. These metal carriers provide electromagnetic interference (EMI) shielding, connectors, ejector levers, or handles to protect against ESD. Although each carrier is designed to protect the boards, an antistatic strap should be used. Remember to handle the carriers by the ejector levers, handles, and carrier edges only; never touch the circuitry or connector pins.

Caution Always tighten the panel fasteners on the Cisco 5814 dial shelf cards and dial shelf controller cards and the captive screws on the Cisco 7206 router shelf network processing engine and I/O controller. These screws prevent accidental removal, provide proper system grounding, and help ensure that the bus connectors are properly seated.

The following are guidelines for preventing ESD damage:

•Always use an ESD wrist strap or ankle strap and ensure that it makes good skin contact.

•Verify that the equipment end of your ESD strap is attached to an unfinished chassis surface when handling a dial shelf card, module, or port adapter; do not touch the printed circuit board, and avoid contact between the printed circuit board and your clothing. When working with a dial shelf card, module, or port adapter, always place it “component side up” on an antistatic surface or in a static shielding bag. If returning an item to the factory, immediately place it in a static shielding bag.

•Ensure that all dial shelf cards and dial shelf controller cards within the Cisco 5814 dial shelf and the I/O controller and network processing engine within the Cisco 7206 router shelf are fully inserted in their respective chassis slots. Ensure that all ejector levers are in their locked positions and that all captive screws are properly tightened. The captive installation screws prevent accidental removal, provide proper grounding for the system, and help ensure that the bus connectors are properly seated.

Caution For safety, periodically check the resistance value of the antistatic strap. The measurement should be between 1 and 10 Mohm.

Rack-Mounting Considerations

In a typical rack-mount configuration, you mount both the dial shelf and the router shelf together in a rack, with the dial shelf mounted below the router shelf. We do not recommend that you separate the dial shelf from the router shelf when configuring the hardware for this system; however, a 20-ft. interconnect cable is available if you need to install the router shelf in an adjacent rack. If you are using AC-input power, you mount the AC-input power shelf below the dial shelf.

There is no clearance requirement for mounting the router shelf directly above the dial shelf; however, if you install anything other than a Cisco 7206 router shelf above the dial shelf, follow the appropriate clearance requirements for the unit you install.

You can stack two access servers in a single rack; however, you must leave a minimum clearance of one rack unit between the two systems.

You must install the AC-input power shelf one rack unit, 1.75 in. (4.28 cm) below the dial shelf to accommodate the DC power cables, the monitor cable, the grounding cable, and the required safety cover.

2-16Cisco AS5800 Universal Access Server Hardware Installation Guide