Below are the step-by-steps instructions to troubleshoot this issue.  Each of the these steps is a possible solution.  Make sure to check the sound from the headphones after each step is completed.

1. Confirm that the headphones are firmly plugged into the headphone jack or connector of the device.  Try to unplug and re-plug the headphones to your audio device to ensure it's properly connected and there are no loose connections.  If your audio device has more than one headphone jack available, make sure the headphones are NOT connected to an audio-in or microphone jack.
2. If your TCL Headphones have a volume control, we recommend setting the volume on the source to a high level and use the volume controls on the headphones to adjust the volume to the desired listening level.
3. If applicable, try to play audio from a different source, a different disc, or switch the TV to a different antenna or streaming channel.  Note: If the issue is resolved at this point, the audio source is the cause.
4. If audio is only heard from the left side of the headphones, ensure that the source device has stereo output capability.  Reminder, a mono device will only output sound to the left side.  
5. If you are using an extension cable to connect the headphones, disconnect the extension cable, then directly connect the headphones to the audio device.
6. Test the TCL headphones on a different audio device. 
7. Test a different set of headphones on the device.  If the issue persists on another player, then the headphones should be replaced.

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