Epson 3865X Plus - Manual (Page 113)

Changing the Jumper Settings
If you change your computer’s configuration or need to alter the
way your computer operates, you may need to change a jumper
setting inside the computer.
A jumper is a small electrical connector that controls one of the
computer’s functions. A jumper’s setting is determined by where
it is placed: either over pin A and the middle pin (position A)
or over pin B and the middle pin (position B), as shown below:
position A position B
A
A
5-6 Installing
and Removing Options