6.4 Replacing DPU Power Trays
6.4.2 Installing the DECmpp 12000/Sx Power Tray
Follow these steps to install the power tray:
1.
Gently slide the new power tray into place, feeding the AC power cord
through the DPU rear skirt assembly. Again, make sure that the fan tray
gasket does not get caught. Before sliding the tray in the last few inches,
make sure that there are no cables in the back of the DPU blocking its way.
2.
Replace six screws, securing the power tray to the frame and air plenum.
3.
Connect the +12 V and –12 V cables to the power supply. To avoid snapping
the power post, apply minimum force when tightening the nut.
4.
Install the –5 V cables. The cable going to the top post (+) is actually ground
if you didn’t mark the cable earlier.
5.
Install the +5 V power bars. It is easiest to install the positive bar first,
followed by the negative bar.
6.
Connect 2-pin connectors to the back of the power tray:
a.
Left connector from the DPU interface PCA
b.
Middle connector for daisy-chaining other machines
c.
Right connector from the temperature sensor
7.
Make sure that all cables are connected properly and install cable restraints,
fastening cables to the power tray.
8.
Before proceeding, ensure that all PCBs have been removed from the
backplane.
9.
Ensure that there are no shorts in the DC voltage supply system. With an
ohmmeter, check the +5 V, –5 V, +12 V, and –12 V connections with respect to
ground. A zero ohm reading indicates a short and must be investigated before
applying power.
10. Plug the power cable into the source of power.
11. Set the 30 A circuit breaker to ON.
12. Set the power selector switch set to LOCAL.
13. Turn on power to the DPU with the keyswitch.
14. With a digital voltmeter, measure all DC voltage levels. Measure the voltages
on the backplane as described in Chapter 3. If needed, adjust the appropriate
levels on the power supply. Make sure you have checked all voltage levels.
15. Turn off the DPU.
16. Reinstall and secure all card cage PCBs using the ejector levers, seating them
firmly into the backplane.
17. Turn on the power to the DPU.
18. Remeasure the DC voltages and fine tune them if necessary.
19. Close the front door.
20. Turn on the server.
21. Run diagnostics and applications to verify the system operation.
Removal and Replacement Procedures 6–13
