IBM iSeries 270 Service Manual page 72

2. Disconnect the power cord from the system unit.
3. Open the front cover. (See "Models 830/SB2 with FC 9074 - Covers" on page 58.)
Refer to Final assembly, front - Models 830 and SB2 with FC 9074 (See page 400) and perform the
following steps.
4. From the front of the system do the following:
a. Remove the EMC access plates from the disk unit enclosures that are located in front of the
backplane that you are replacing. For location information, see "Locations — Models 830, SB2
System Unit with FC 9074 Base I/O Tower" on page 260. Press the surfaces of the two latching
mechanisms together and tilt the top of the cover away from the frame to remove it.
b. Record the locations of the disk units and then remove them from the disk unit enclosures that you
just uncovered.
Attention: The disk units are sensitive to electrostatic discharge (see "Work with electrostatic
discharge-sensitive parts" on page 585).
c. Remove the screws that hold the disk unit cage assembly in to the frame.
d. Remove the two retaining screws that are located inside of the disk unit cage assembly (the top
right and bottom left corners).
e. Remove the disk unit cage assemblies.
f. Remove the screws that hold the DASD shelf to the frame.
g. Remove the DASD shelf from the frame.
5. Remove the retaining screw that is holding the DASD board assembly to the frame.
6. Pull the DASD board assembly out until it slides off the guide pins, then rotate the DASD board
assembly 90 degrees to remove the cables that are located on the backside of it.
Figure 1. Device board cabling
7. Remove the cables from the rear of the DASD board assembly and note their locations.
Note: Both ends of the ribbon cables are marked LH or RH indicating that one end of the cable is
plugged in to either the left-hand (DB1) or right-hand (DB2) DASD board assembly. The other end of
the cable is plugged in to either the left-most (LH) or right-most (RH) DASD controller card. The cables
will crisscross in the center of the tower.
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Hardware (Remove and Replace; Part Locations and Listings)