If your home theater receiver is not producing any sound when using only the speakers and not a source connected to it, there could be a few potential causes for this issue:
Input Selection: Make sure that the input source on your receiver is correctly selected or set to the appropriate input. If the receiver is set to an input that doesn't have an audio signal connected, you may not hear any sound.
Mute Function: Check if the receiver has a mute function enabled. It's possible that the mute button on the receiver or the remote control has been pressed, silencing the audio output. Ensure that the receiver is not muted and that the volume is turned up.
Speaker Configuration: Verify that the speaker connections are properly set up and the speakers are connected to the correct terminals on the receiver. Check for any loose or disconnected speaker wires or cables. Ensure that the speaker settings on the receiver are configured correctly, such as the speaker size, crossover settings, and channel levels.
Amplifier Fault: It's possible that there is an issue with the amplifier section of your receiver. If the amplifier is not functioning correctly, it may not be able to produce any sound even if the speakers and other connections are fine. In this case, it may require professional repair or troubleshooting.
Internal Settings: Some receivers have internal settings that can affect the audio output, such as audio mode (stereo, surround, etc.), sound processing settings, or firmware settings. Check the receiver's user manual for any specific settings that might need adjustment.
If you have checked these potential causes and are still experiencing no sound from your home theater receiver, it may be advisable to consult the manufacturer's support or contact a professional technician for further assistance and troubleshooting.