Onkyo TX-RZ3100 User Manual page 120

Troubleshooting
Audio
Make sure that the speaker setup microphone is not still connected.
Confirm that the connection between the output jack on the device and the
input jack on this unit is correct.
Make sure that none of the connecting cables are bent, twisted, or damaged.
If the MUTE indicator on the display flashes, press on the remote controller
to cancel muting.
While headphones are connected to the PHONES jack, no sound is output
from the speakers.
When "Source" ­ "Audio Select" ­ "PCM Fixed Mode" in the Setup menu is set
to "On", no sound is played when signals other than PCM are input. Change
the setting to Off.
Check the following if the above does not fix the problem:
There is no sound from the TV
No sound from a connected player
A speaker produces no sound
The subwoofer produces no sound
Noise can be heard
The beginning of audio received by an HDMI IN cannot be heard