Try the other inputs and see if you have the same problem with them. That will let you know if the problem is the tuner or if it is something else.
Since your receiver does not shut off after a few seconds it should not have an amplifier problem. If it did shut off quickly it is know as the protect mode and normally indicates that you have a blown channel, not always, but normally it is that.
If you get no audio from any function, you may have a digital board problem which is a very difficult problem to isolate and repair.
A couple of things you can do to make sure it is not something like a wrong setting is to make sure that the "Tape Monitor" switch has not been pressed accidentally. If the "Tape Monitor" is engaged it wil appear that everything is normal with the display and functions, but you get no audio from anything unless you are recording on a tape. This can happen even with no tape deck connected to the unit. Study the display closely and see if "monitor" or "tape monitor" is lit up anywhere in the display, or if you have an led on the tape monitor or monitor switch, that led could also be lit up red. If you turn the volume up all the way, do you get a very faint amount of audio? If so, you probably do have the tape monitor engaged.
Also check that the speakers are activated. If you have only one set of front speakers you want to make sure that only those speakers are activated. You will have a button for speakers "A" and "B". Make sure that only speakers "A" are turned on. Some receivers will not have any output if you have both "A" and "B" turned on but only have speakers connected to the "A" speakers.
If your receiver has a button for the headphones make sure that is not engaged as well. Many receivers will not have output to the speakers if the headphones are turned on. Or if you have headphones connected, try unplugging them.
Those the only user type of things that you can do unless you have some good electronics troubleshooting skills and the proper tools. So if you have checked those things and still have no audio you need to take it in for service.
Here is a link that you can get your owners manual from online for free. It is always a good idea to study the owners manual to make sure you have everything connected properly and have the settings correct as well. Just go to this link and put in your model number exactly as it is on the front of the receiver to make sure you get the right manual. If you put in the wrong model number you will get no results when you search for it.http://books.jvcservice.com/
I hopes this helps, and if so a "FixYa" rating would be appreciated.