The Roland DR-660 drum machine has a number of features and corresponding settings. When the unit is unplugged from its power source, a small battery is used to keep these settings stored in memory. When this battery dies, the unit will begin presenting error messages and will be unable to store settings when removed from power. Replacing the internal battery will solve this issue.
Disconnect all of the cables hooked up to the unit and turn it off. Turn the DR-660 upside down and remove each of the screws holding the bottom cover in place. Pull the cover off, exposing the internal components.
Remove the screws holding the circuit board in place. Slide the circuit board toward the right side of the unit and gently pull it out. The battery, a small button cell, will now be visible.
Pull the battery out of its holder. Replace it with a new lithium battery, size 2032. Insert the new battery with the positive side facing up. Replace the circuit board and back cover, ensuring that all of the screws are reinstalled.