
AC Repair and Adjustment Procedures
FRP 3: Power Supply Replacement
HMM-168-A
Cray Research/Silicon Graphics Proprietary
25
Heat Sink Replacement
Before you replace a power supply, you must move the heat sink from the old
power supply to the new supply. The following procedure provides details.
is an exploded view of the assembly.
1.
Remove the heat sink cover:
a. Use a #1 Phillips screwdriver to remove the 8 screws (and washers).
b. Pull the cover straight up and off.
c. Set the cover nearby, with the flat side (outside) down.
2.
Remove the heat sink:
a. Loosen the seven 2.5-mm hex bolts that hold the heat sink to the power
supply (refer to
). We recommend that you leave the bolts in
the heat sink after you loosen them. The bolts are different lengths and
must remain in their original positions.
b. Loosen the four 3-mm hex bolts (and washers) that hold the heat sink
to the power supply (refer again to
). Leave the bolts in the
heat sink after you loosen them. The bolts are different lengths and
must remain in their original positions.
c. Pull the heat sink off of the power supply with firm upward pressure. It
may be necessary for you to gently pry the heat sink loose at a corner.
d. Ensure that you have a replacement thermal pad, then remove the old
thermal pad and discard it. (A replacement thermal pad comes with the
replacement power supply.)
e. Remove any bits of thermal pad left on the heat sink.
It is not necessary to remove the white thermal compound (if there is
any) from the heat sink; however you should ensure that the compound
does not clog any air vents.
CAUTION
The hex bolts can strip if you use the wrong tool or an inferior tool.
Use sockets from “Socket set, Hex Bit 1/4” Drive Metric,” P/N
53267200. Use caution when you loosen and tighten the bolts.