Epson 386/25 - Manual (Page 209)

Changing the Jumper Settings
The hard disk drive jumpers are located on the drive’s circuit
board, near the large cable connector.
The jumpers on your drive may be in a slightly different
location, but you set them the same way.
There are four positions for the jumpers on each hard disk drive.
Jumpers are installed in only two of the positions and the other
two positions are left open.
Installing and Removing Disk Drives B-5