Epson 386/25 - Manual (Page 214)

3. Locate one of the power supply cables that lead from the
power supply in the computer (behind the horizontal drive
bays). The cables are labelled Pl, P2, or P3 and have a clear
plastic connector on one end. You can use any of the three
cables. As shown below, the end of the connector has two
notched corners.
power supply cable power supply socket
notched
corners
notched
corners
The power supply socket is on the back of the hard disk
drive, next to the cable you just connected. The socket also
has two notched corners, as shown above.
Align the connector with the socket so that the notched
corners on the connector line up with the notched corners
of the socket.
notched corners
Installing and Removing Disk Drives B-15