The TD-25 contains an Auto Off feature which shuts down the power after it has not been used for four hours. This feature is designed to conserve power in case you forget to turn off the TD-25 using its power switch on the back panel.
Here are the steps if you'd like to disable the Auto Off feature:
1. Press the function 3 button.
2. Press function 3 again (SETUP).
3. Press ENTER (KICK button) for "OPTIONS."
4. Press function 3 to highlight "4 HOURS" for the Auto Off setting.
5. Turn the INSTRUMENT knob counterclockwise to choose "OFF."
6. When you're finished, press the function 1 button(EXIT) 3 times to return the main menu. The new setting is saved automatically.