Hello. My name is***** can help you with your question.
That would be very unusual. Have you checked the settings of the projector? Just to make sure that the sound is not muted and is set to come out of the projector? What is the input cable you are using for and what device is it coming from?
If what you're saying is that it does output audio when it's connected to a certain computer, then that would indicate that the projector itself is working properly. It may just be that there is a setting on your receiver or wherever the HDMI cable is coming from that is not passing through the audio. I would check everything in between your video source and the projector. In fact I would plug a cable directly from the video source to the projector cutting out anything in between at least temporarily to test it.
If you connect the projector to a different source, do you get audio or do you experience the same problem? It sounds like you have try that but I just want to make sure.
There is one more thing I would suggest to narrow this down – and that is connecting an analog audio source – using the red and white RCA jacks. This will help us to determine whether or not it is in the HDMI circuit or if the projector in general is not producing sound.