Car Radio issue - sound goes away, then comes back after a specific amount of time...

Hi,

I've got a 86 Nissan Stanza and when I turn the radio on, the music comes on. Then it will go off for a specific period of time, and then come back on for good. The period of time it is off seems to be growing. The radio itself looks fine during this music off time, display is good and still showing the tuned station. Any ideas of where I should start to figure this out?

Thanks,

Alan