Epson Equity 320SX PLUS - Manual (Page 152)

7. Align the connector with the socket so that the row in
the connector with the blocked hole lines up with the
row in the socket with the missing pin, as shown below.
Make sure the holes fit over all the pins and then push in
the connector.
8. Looking at the subassembly, locate one of the power
supply cables that lead from the power supply (behind
the horizontal drive bays). The cables are labelled Pl, P2,
and P3; you can use any one. As shown below, the end of
the connector has two notched corners.
7-24 Installing and Removing Disk Drives