DRX-3.3 - Sleep Timer

You can allow the unit to enter standby automatically when the specified time
has elapsed. Press the Sleep button on the remote controller, and select any of
"30 min", "60 min" and "90 min".
"Off": The unit does not automatically enter standby mode.

NOTE: You can also set this by pressing the [SETTING] button on the remote controller and
selecting "6. Hardware" - "Power Management" - "Sleep Timer" on the
Setup menu