IBM RT User's Setup Manual page 225

2-50 Options Installation
3. If the drive is to be reinstalled in drive position C, set the
adapter to the side. It will be reinstalled in a later procedure.
4. Remove the cooling fan assembly. See "Cooling Fan Removal"
on page 2-5.
5. Disconnect P15 on the power cable from the 4-pin connector on
the rear of the fixed-disk drive in position E. Disconnect the
ground wire from the ground tab on the drive.
Note: Internal fixed-disk drives may differ in appearance.
Data, signal, and power connectors, however, remain in the
same relative positions.
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