Cisco 3660 - Manual (Page 4)

4 Replacing the Mainboard in Cisco 3660 Routers
Safety Recommendations
Safety with Electricity
Warning The ISDN connection is regarded as a source of voltage that should be inaccessible to user
contact. Do not attempt to tamper with or open any public telephone operator (PTO)-provided
equipment or connection hardware. Any hardwired connection (other than by a nonremovable,
connect-one-time-only plug) must be made only by PTO staff or suitably trained engineers.
Warning Before working on equipment that is connected to power lines, remove jewelry (including
rings, necklaces, and watches). Metal objects will heat up when connected to power and ground and
can cause serious burns or weld the metal object to the terminals.
Warning To avoid electric shock, do not connect safety extra-low voltage (SELV) circuits to
telephone-network voltage (TNV) circuits. LAN ports contain SELV circuits, and WAN ports
contain TNV circuits. Both LAN and WAN ports may use RJ-45 connectors. Use caution when
connecting cables.
Warning Hazardous network voltages are present in WAN ports regardless of whether power to the
router is OFF or ON. To avoid electric shock, use caution when working near WAN ports. When
detaching cables, detach the end away from the router first.
Warning Before opening the chassis, disconnect the telephone-network cables to avoid contact
with telephone-network voltages.
Warning Do not work on the system or connect or disconnect cables during periods of lightning
activity.
Warning Do not touch the power supply when the power cord is connected. For systems with a
power switch, line voltages are present within the power supply even when the power switch is OFF
and the power cord is connected. For systems without a power switch, line voltages are present
within the power supply when the power cord is connected.
Follow these guidelines when working on equipment powered by electricity:
•
Locate the emergency power-OFF switch in the room in which you are working. Then, if an
electrical accident occurs, you can quickly shut the power OFF.
•
Before working on the router, turn OFF the power and unplug the power cord.
•
Disconnect all power before doing the following:
— Installing or removing a router chassis
— Working near power supplies
— Performing most hardware upgrades
•
Do not work alone if potentially hazardous conditions exist.
•
Never assume that power is disconnected from a circuit. Always check.
•
Look carefully for possible hazards in your work area, such as moist floors, ungrounded power
extension cables, and missing safety grounds.