IBM iSeries 270 Service Manual page 39

To remove or replace the system unit backplane (MB1) and power distribution board (PB1):
1. Power off the system. See Power on/off the system and logical partitions.
2. Unplug the power cord from the back of the system unit.
3. Remove the following:
a. The right side cover. See Model 820 - Covers.
b. The PCI cards, processor and memory riser cards, labeling each. See Model 820 - Cards
(dedicated).
c. All the plastic card dividers.
d. The screws securing the processor and memory cage to the frame.
e. The power supplies. Unplug the AC cable and cables that connect to the disk unit cages, power,
and control panel function cables.
f. The screws securing the upper card cage to the lower processor cage.
g. The lower processor cage by pulling it out of the frame.
h. The cable running from the system backplane to the rear of the frame.
i. The screws holding the SPCN connector plate to the rear of the frame. Pull out the plate.
j. The screws that mount the boards and stiffener to the frame.
4. Remove the system unit backplane, the power distribution board, and stiffener board. This is all one
FRU.
Note: There is an insulator attached to the board. If the new assembly does not have an insulator,
use the insulator from the assembly you just removed.
5. Reverse the procedure to replace the board. Then, continue with the next step.
Note: Be sure to close the cable catches on the power supply side of the power distribution
backplane.
6. Perform the following:
a. Open the front cover. (See "Model 820 - Covers" on page 21.)
b. Pull on the two side fasteners to release the control panel.
c. Slide the panel partially out of the frame.
d. Insert the keystick into the panel.
e. Plug the power cord back into the system frame. Do not power on the system yet. The panel
should display SRC 0000 5553.
Figure 1. System unit control panel with keystick (NB1)
Analyze hardware problems
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