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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
Chapter6 Maintaining the Cisco MGX Switch or Gateway
Swapping a Primary or Redundant DC Power Entry Module with Power On
Figure6-1 DC PEM Faceplate
Step6 Disconnect DC source wires at the wiring terminal blocks on the DC PEM. Proceed to Step 10.
Step7 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 w hen 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 br eaker on the still-active PEM opens,
shutting down the system.
Step8 At the backplane end of the system power cable, loosen the captive screws on the cable bracket.
Step9 Pull the cable bracket out approximately 1 inch to disconnect the cable.
Step10 At the en d of the system power cable connected to the DC PEM, loosen the jack screws and disconnect
the cable from the DC PEM.
Step11 Rem ove the DC PEM.
Step12 Make sure that both the DC PEM and the branch circuit breakers are in the off position.
Step13 Insert the replacement DC PEM and tighten the captive mounting screws.
Step14 Connect the system power cable at the DC PEM.
Step15 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:
1Two-position circuit breaker. The positions
are Off and On.
4Plastic cover.
2J1 output connector. 5Terminal block 1 (DC input).
3LED showing status of the DC PEM.
J1
-48V
OFF ON
RTN
DC OK
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