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What to do if you can't hear sound on your CommBox Classic S5

No sound coming from your CommBox Classic S5? Follow these simple steps to check your sound settings, connections, and input source to get your audio working again.

pplies To

CommBox Classic S5: CBIC65S5, CBIC75S5, CBIC86S5, CBIC98S5

Step-by-Step Instructions

Step 1: Check the volume

  • Press the Volume Up button on the remote or side of the screen

  • Confirm the volume is not muted

  • Check the volume on your connected device (e.g. laptop or media player)

💡 Tip: If you’re using a laptop, make sure it’s not muted and volume is turned up.

Step 2: Confirm the input source

  • Swipe up from the bottom of the screen

  • Check the active input (HDMI 1, USB-C, etc.)

  • Make sure the correct source is selected for your device

Step 3: Check your cables

  • Make sure your HDMI or USB-C cable is securely connected

  • If using VGA, remember it does not carry sound – use a 3.5mm audio cable as well

  • Try a different HDMI port or a new cable if needed

Step 4: Open the audio settings

  • Tap the Settings icon

  • Go to Display & Sound or Sound Settings

  • Confirm that the Audio Output is set to Built-in Speakers (not Bluetooth or SPDIF unless you're using those)

💡 Tip: If you've recently used Bluetooth headphones or a speaker, the screen might still be trying to send sound there.

Step 5: Reboot the screen

  • Turn the screen off using the power button or remote

  • Wait 10 seconds, then turn it back on

  • Test the sound again

Step 6: Try a different app or source

  • Open a different app like YouTube or Whiteboard and check for sound

  • If you're using an external device (like a laptop), try playing audio directly on the screen instead

Troubleshooting / What to Do If It Still Doesn’t Work

  • Still no sound from HDMI? Make sure your device is set to use HDMI audio in its sound settings

  • Only some apps have sound? Check the volume inside the specific app

  • Bluetooth is stuck on? Go to Bluetooth settings and disconnect any paired devices

  • Sound is crackling or distorted? Try a new cable or switch to USB-C

If problems continue, log a ticket on the CommBox Support Portal for further assistance.