Epson EL 486UC - Manual (Page 54)

Changing the Jumper Settings
The main system board in your computer has a number of
jumpers that control certain functions. These jumpers are preset
at the factory to default positions. See the illustration below to
locate the jumpers on the system board.
Note
These are the only jumpers you may need to change. Other
jumpers on the system board are for service purposes only.
4-6 Installing and Removing Options