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Caution
Before proceeding to the next step, verify that the source DC circuit breaker
servicing the DC power supply you are replacing is in the OFF position. Also verify that
the power switch on the DC-input power supply is OFF (O). As an additional check,
measure the voltages across the DC power cable leads you intend to attach to the power
supply. All readings should be zero volts.
Thread the source DC power cable leads up underneath the power supply handle.
Step 6
Allow sufficient slack in the power cable for strain relief.
The color coding of the source DC power cable leads to the DC-input
Note
power supply depends on the color coding of the site DC power source.
Typically, green or green/yellow is used for ground. Since there is no color code
standard for the DC wiring, you must ensure that the proper polarity is connected
to the DC-input power supply. In some cases, the source DC cables might have
a (+) or a (–) label. This is a relatively safe indication of the cable polarity.
When installing the unit, the ground connection must always be made first and
Warning
disconnected last.
Remove the nut and locking washer from each power supply threaded terminal
Step 7
and attach the source DC power cable lugs to the power supply terminals in the
following order: ground to ground, positive (+) to positive (+), and negative (–)
to negative (–). (See Figure 7-11.)
Thread the power supply circuit breaker external alarm leads (if present) up
Step 8
through the power supply handle and attach them to the circuit breaker alarm
terminal block on the power supply faceplate according to the notes you made
in a previous step. (Some sites might not be equipped with a power supply circuit
breaker external alarm.)
Removing and Replacing a DC-Input Power Supply
Maintaining the Cisco 12012 7-27
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Troubleshooting
