Electrostatic Discharge; Site Requirements - Cisco uBR924 Installation Manual

Chapter 2 Preparing for Installation

Electrostatic Discharge

Electrostatic discharge (ESD) damage, which occurs when electronic cards or components are
improperly handled, can result in complete or intermittent system failures. The
Cisco uBR924 cable access router consists of a printed circuit board that is housed in a metal enclosure.
Electromagnetic interference (EMI) shielding and connectors are integral components of the enclosure.
Although the enclosure helps protect the boards, use an antistatic strap whenever handling the
Cisco uBR924 cable access router. This will minimize the possibility that ESD damage can occur to the
internal boards by touching the external connectors.
Following are guidelines for preventing ESD damage:
•
•
Caution For safety, periodically check the resistance value of the antistatic strap. The measurement
should be between 1 and 10 megohm (Mohm).

Site Requirements

Before going to a subscriber site to install the Cisco uBR924 cable access router, verify that the
following have been done:
•
Cisco recommends that a dedicated (new) CATV cable drop be run from the grounding
Note
block directly to the Cisco uBR924 cable access router. If such a drop is not available,
careful qualification of existing cable is often necessary. Cable ground should be
connected to the grounding system of the building or residence as close to the point of
cable entry as practical. For the United States, refer to the National Electrical Code
Section 820-40 guidelines for proper grounding.
•
•
Note Installing a high pass filter between the Cisco uBR924 router and the headend will prevent
the router from connecting to the headend—in this situation, the router's US LED will
never light.
OL-0338-01 (3/2000)
If you use an ESD wrist strap or ankle strap, ensure that it makes good skin contact and that the
equipment end of the ESD strap is attached to an unfinished surface of the
Cisco uBR924 cable access router.
Always place the router on an antistatic surface or in a static shielding bag. If you are returning the
item to the factory, immediately place it in a static shielding bag.
Ensure that a coaxial cable connection is run from the cable TV trunk to the subscriber building or
residence. For sites that support multiple telephones or fax devices on a VoIP telephone line, ensure
all wiring is in place to support the configuration.
Verify that each subscriber site is characterized at the headend to support upstream transmission
and meets DOCSIS upstream and downstream RF requirements. Observe procedures in the NCTA
Recommended Practises for Measurements on Cable Television Systems. Also see the "Cabling"
section on page 6.
Some sites specify that high pass filters must be installed on every tap drop that does not carry
upstream data, voice, or IPPV services.
Cisco uBR924 Router Hardware Installation Guide
Site Requirements
2-3