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Cisco MGX 8800/8900 Series Hardware Installation Guide
Releases 2 - 5.2, Part Number OL-4545-01, Rev. H0, May 2006
Chapter 6 Maintaining the Cisco MGX Switch or Gateway
Swapping a Primary or Redundant DC Power Entry Module with Power On
Figure 6-1 DC PEM Faceplate
Step 6
Disconnect DC source wires at the wiring terminal blocks on the DC PEM. Proceed to Step 10.
Step 7 If your terminal block does not have a plastic cover, locate the backplane end of the system power cable
for the DC PEM that you intend to replace.
Caution The cable connector must be disconnected at the backplane first, when you are inserting or removing the
PEM with power on. If you disconnect the cable at the PEM first when power is on, the cable contacts
are energized. If the energized cable contacts touch the surface of the chassis or any metal connected to
the chassis, the –48 VDC is shorted to the chassis, and the circuit breaker on the still-active PEM opens,
shutting down the system.
Step 8 At the backplane end of the system power cable, loosen the captive screws on the cable bracket.
Step 9 Pull the cable bracket out approximately 1 inch to disconnect the cable.
Step 10 At the end of the system power cable connected to the DC PEM, loosen the jack screws and disconnect
the cable from the DC PEM.
Step 11 Remove the DC PEM.
Step 12 Make sure that both the DC PEM and the branch circuit breakers are in the off position.
Step 13 Insert the replacement DC PEM and tighten the captive mounting screws.
Step 14 Connect the system power cable at the DC PEM.
Step 15 Connect the backplane end of the system power cable to the backplane. This requires some dexterity,
especially if the cabling around the system power cable is dense. Grasp the cable bracket at the captive
screws and gently push the bracket straight in. Furthermore:
1 Two-position circuit breaker. The positions
are Off and On.
4 Plastic cover.
2 J1 output connector. 5 Terminal block 1 (DC input).
3 LED showing status of the DC PEM.
J1
-48V
OFF
ON
RTN
DC OK
84460
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