Epson Equity 320SX PLUS - Manual (Page 153)

The power supply socket on the back of the drive is next
to the ribbon cable connector. The socket also has two
notched comers, as shown below.
power supply cable power supply socket
notched
corners
notched
corners
Position the power supply cable connector so that the
notched comers on the connector line up with the
notched comers of the power supply socket on your
drive. Make sure the holes fit over all the pins and then
push in the connector.
Caution
If you do not correctly align the holes with the pins,
you could severely damage your drive when you push
in the connector.
Installing and Removing Disk Drives 7-25