Connect your 7.1 (or 5.1) speaker setup, ensuring positive (+) and negative (-) terminals match.
Often indicates speaker wire issues. Turn off, check for frayed wires touching the back panel, and turn back on.
Use the AUTO/ALC/DIRECT button or STANDARD button to toggle surround modes.
Ensure HDMI CEC is active on TV/receiver, or check that input assignment matches the cable.
Use the Input Selector knob or remote to select your source (HDMI 1, DVD, etc.).