6.4 Replacing DPU Power Trays
6.4.3 Removing the DECmpp 12000–LC/Sx Power Tray
Caution
It is important to label all cables as you disconnect them. Reinstalling
cables with the wrong polarity can render the system inoperative.
Follow these steps to remove the power tray:
1.
Shut down the DECstation and turn off power to the workstation and the
DECmpp 12000–LC, as described in Chapter 1.
2.
Set the DPU breaker switch to OFF, and unplug the power cord from the
power source.
3.
Open the DPU back door.
4.
To avoid possible problems when powering up, use the ejector levers to detach
each PCB from the backplane.
5.
Disconnect all cables at the back of the power tray.
6.
Open the DPU front door and remove the front inner door.
7.
Using a 9/16-inch open-end wrench or socket wrench, remove the cables from
the +5 V power supply.
8.
Remove the –5 V, +12 V, and –12 V wires from the power supplies:
•
Powertec — Using a 5/16-inch socket wrench, remove the –5 V, +12 V, and
–12 V wires
•
HC Power — Using a Phillips screwdriver, remove the –5 V, +12 V, and
–12 V wires
9.
Remove the four Phillips Screws holding the power tray to the frame.
10. Make sure you have removed all of the cables from the back of the power tray.
Caution
Do not let the power cables get caught on the power tray when sliding it
in or out. If the cable insulation is cut, it can cause a direct short.
11. From the DPU front, carefully lift the power tray cables out of the way while
pulling the power tray out of the enclosure.
12. Lay the power tray down flat or on its side. Do not put weight on the back of
the tray.
6–14 Removal and Replacement Procedures
