soundbar keeps turning itself off after about 15 minutes when i'm watching something

Diagnosis

The Samsung HW-B650 is equipped with an energy-saving feature called Auto Power Down (APD). This system is designed to automatically shut the unit off if it detects no audio signal for a continuous period of 15 minutes. While this is intended to save electricity, it often triggers prematurely if the audio signal coming from the TV is too low or if the volume is set primarily on the soundbar rather than the source device. When the input level from the TV's HDMI (ARC/eARC) or Optical port drops below a specific decibel threshold, the soundbar "assumes" there is no content playing and initiates the shutdown sequence. This is common when watching quiet scenes in movies or when using external streaming boxes (like Apple TV or Roku) that output a low-voltage signal. You can confirm this is the cause if the soundbar consistently shuts off regardless of the content, but stays on if you manually increase the TV's output volume to 70% or higher.

How to Fix It

To stop the soundbar from turning itself off, you must manually disable the Auto Power Down function. Because this is a system-level setting, it is not found in the standard on-screen menu but must be triggered via a specific remote sequence:

1. Power on the soundbar and ensure it is in "Standby" or "On" mode.
2. Locate the Settings/Gear button on your Samsung remote control.
3. Press and hold the Settings/Gear button firmly for approximately 5 to 10 seconds. Do not let go until the small LED display on the front of the soundbar reacts.
4. Watch the display panel; it will flash and eventually display the text "APD OFF".
5. Once you see "APD OFF," release the button. The soundbar is now configured to remain powered on regardless of the signal strength.
6. To verify, play a very quiet audio track; the unit should no longer power down after the 15-minute mark.

If That Didn't Work

• Check HDMI-CEC (Anynet+) Settings: If the TV is sending a "Sleep" or "Power Off" command via HDMI-CEC, the soundbar will shut down even if APD is off. Go to your Samsung TV settings under General > External Device Manager > Anynet+ (HDMI-CEC) and toggle it off and back on to reset the handshake. If using a non-Samsung TV, look for "CEC" or "Link" settings in the TV menu and ensure the "Auto Power Off" sync is disabled.
• Inspect the HDMI Cable: A faulty or outdated High-Speed HDMI cable can cause intermittent signal drops. If the soundbar loses the "handshake" with the TV for even a second, it may trigger a reboot or shutdown. Replace the cable with a certified HDMI 2.1 Ultra High Speed cable to ensure the eARC channel remains stable.
• Update Firmware via USB: Outdated firmware on the HW-B650 can cause power management bugs. Download the latest firmware from the Samsung support site onto a FAT32 formatted USB drive. Insert the drive into the service port on the back of the soundbar, power it off, then power it on; the display will show "UPDATE" and then "COMPLETE."
• Verify Power Source: Ensure the soundbar is plugged directly into a wall outlet rather than a crowded power strip or a "smart" surge protector that may be cutting power due to low current draw. A fluctuating power supply can trigger the internal protection circuit to shut the unit down.

Heads Up

• Volume Balancing: To prevent signal drops in the future, set your TV's output volume to 80-90% and use the soundbar remote to control the actual listening volume. This ensures the soundbar always receives a "strong" signal.
• Avoid Blockage: Ensure the back of the soundbar has at least 3 inches of clearance from the wall to prevent overheating, as thermal shutdown can mimic the 15-minute APD timer.
• Resetting: If the unit becomes unresponsive, you can perform a hard factory reset by holding the Volume + and Volume - buttons on the main unit (not the remote) simultaneously for 5 seconds until "INIT" appears on the display.