Service manual

GS160/320 Component Removal and Replacement 4-47
Removal (This procedure requires two people.)
The hierarchical switch FRU comes cabled for a GS160 and contains clock and power
cables for a GS320. This procedure describes replacing a FRU in a GS320. If your
system is a GS160, omit step 6. Ground cables for the H-switch stay in the system box.
1. Shut down the operating system(s).
2. Remove all AC power by tripping the main circuit breakers on all AC input boxes.
3. Open the system cabinet front and rear door(s).
4. Remove all global ports from all QBBs. See Section 4.5.6.
5. Disconnect all coax clock cables at the clock splitter end and thread them out of the
system boxes. (The spare comes with 8 cables for 8 QBBs.) See Section 4.5.4.
6. (GS320 only) Disconnect the blue cables that go to global ports in QBBs 4, 5, 6, and
7 at the H-switch end. Insert the blade end of a flathead screwdriver between the
plastic cable guide and the lip of the connector then twist one end of the cable loose.
Repeat this procedure on the other end of the cable and fully disconnect.
Finally
thread the cables out of the switch.
7. Disconnect the four power cables powering the H-switch at the system box end. The
spare comes with four cables, one for each system box.
8. Disconnect the ground cables at the H-switch end and thread them out of the switch.
Retain the hardware for installation. The spare does not come with these cables.
9. Disconnect the CSB cable at the bottom of the H-switch housing.
10. Unscrew the blower channel(s) at the bottom of the H-switch housing and push them
part way back into the blower cavity.
11. On the left side of the H-switch housing, unscrew the three captive screws holding
the midpanel bracket to the H-switch housing and cabinet.
Remove.
12. Remove the remaining screws holding the H-switch to the system cabinet. If the
system is a GS160, you will have to use a long screwdriver threaded through the
frame to reach screws on the right side of the H-switch. Make sure that the last
two screws removed are on the bracket upon which the H-switch housing
pivots at the top, rear, left corner of the housing.
13. With two people lift the H-switch off its bottom pivot and remove it.
Replacement
Reverse the steps outlined in the removal procedure.
Verification
Power up the system and check that the H-switch is functioning.