Maintaining the Cisco12008 7-33
Adding, Removing, or Replacing a DC-Input Power Supply
Warning To be completely sure that power has been removed from the source DC circuit
presently servicing the power supply that you intend to remove, use a voltmeter to measure
the voltage across the negative (–) and positive (+) source DC leads. Set the voltmeter to a
range that makes it capable of measuring up to 75 VDC. The measurement across the
positive and negative leads should be zero (0) volts.
Step5 Before removing the power cables, write the name of each cable on a piece of
tape, as follows:
•Ground
•+ (positive)
•– (negative)
Step6 Attach each piece of tape to the appropriate cable to identify it for later
reconnection.
Step7 Remove the power cables from the power supply terminals, strictly observing
the following order of removal:
(a) – (negative)
(b) + (positive)
(c) Ground
Step8 Using a 10 mm nutdriver (or a 1/4-inch socket wrench with a 10 mm deep-well
socket), loosen the nuts securing the negative (–) power cable to the bottom
terminals on the power supply faceplate; remove the nuts and locking washers
from the terminals; set this hardware aside temporarily and remove the power
cable from the negative terminals.
Step9 Proceed in like manner to remove the positive (+) and grounding cables from the
power supply terminals, making sure that you remove the ground cable last.
Step10 For added safety, place tape over the exposed lugs of the power cables to prevent
contact between the leads.