Epson 486SX - Manual (Page 96)

Removing the Subassembly
You need to remove the subassembly only if you are installing
or removing the hard disk drive that is mounted next to the
power supply.
Follow these steps:
1. Turn the computer so you are facing the front panel.
2. Disconnect the power supply and drive cables from the
backs of all the drives installed in your computer, as shown
below. Note which cables are connected to which drives so
you can easily reconnect them later.
5-6 Accessing Internal Components