Service manual

Power Cabinet Component Removal and Replacement 5-33
Removal
1. Remove the QBBs in the affected system box from use, by shutting down the
instance of the operating system and using the SRM power off command.
2. Open the front and rear doors of the power cabinet.
3. At the back: if the entire system had to be brought down, trip the main circuit
breaker on the AC input box powering the subrack; otherwise, trip the three circuit
breakers controlling the lines to the subrack. The target subrack and the AC input
box circuit breakers controlling it have the same color code.
4.
Loosen the two screws holding the retaining bracket for the 48 V cable going to the
power cabinet bulkhead and let the bracket drop.
5.
Unplug power cords and signal cables connected to the subrack distribution panel.
6.
Remove the two Phillips head screws holding the subrack to its supporting plate.
7. Move to the front of the power cabinet and remove the power supplies from the
subrack and set aside. See Section 5.4.
8. Remove the plastic fillers at the bottom of the power cabinet to gain access to the
back of the AC input boxes. To remove the fillers, pinch the snaps at both ends of
the guard and pull it away from the frame.
9. Unplug the power cords from the AC input box that go to the target subrack – again
use the color code to determine which cords to unplug.
10. Remove any tie wraps dressing the power cords that would prevent them from being
removed with the subrack.
11. Remove the four Phillips head screws holding the subrack to the frame and slide the
rack out of the cabinet.
Take care that the power cords attached to the back of
the subrack are free to travel with it.
Replacement
Reverse the steps outlined in the removal procedure.
Be sure the power cords are placed back in the same locations from which they were
removed.
Verification
Power on the two QBBs.