AC Repair and Adjustment Procedures
FRP 12: Clock Wire Replacement
HMM-168-A
Cray Research/Silicon Graphics Proprietary
77
Complete
for any cabinet associated with the clock wire.
Associated cabinets include the cabinet(s) where the clock wire connects and
any cabinet(s) through which the clock wire passes.
1.
Open the front cabinet door.
2.
Open the cabinet’s main disconnect circuit breaker (CB1) and unplug the
cabinet. Place a lockout device over the cabinet’s plug and lock/tag it.
You may also open, lock, and tag the customer’s wall breaker(s).
3.
Open the rear cabinet door.
4.
Loosen the eight 1/4-turn captive screws that secure the module panel,
then pull the module panel out of the cabinet at an angle.
5.
Remove panels to provide access to the wire:
If you are replacing a clock wire in the Z-side (top) wiremat: disconnect
the cable from the clock switch board, remove the blower exhaust shield,
and remove the upper plenum panel. (Six #2 Phillips screws hold the
blower exhaust shield in place. Six #1 Phillips screws hold the upper
plenum in place.)
If you are replacing a clock wire in the Y-side (bottom) wiremat: remove
the I/O panel and the lower plenum panel. Eight 1/4-turn captive screws
secure the I/O panel to the cabinet. Twelve #1 Phillips screws hold the
lower plenum in place; four of the screws pass through the top of the I/O
bulkhead.
NOTE:
If the clock wire that you are removing passes from one cabinet to
another, you must access the wiremats in all appropriate cabinets. In
addition, you must open the intercabinet cable ducts as described in
the following step.
WARNING
Ensure that the electrical plug for the
equipment that you service is
unplugged, locked, and tagged. Failure
to do so could result in severe shock
and burns.