Radio stations come and go. In 1990, Power 1490 brought hip-hop to the Tucson airwaves, one of the very few stations in the country to completely embrace the then-nascent genre. By 1995, it was over. There will be a one-time screening of A.M. Mayhem: The Untold Story of Tucson’s Power 1490 at the Fox Tucson Theatre this Saturday, immediately after which the DVD will be made available. More than a walk down memory lane, this documentary, directed and produced by former Power personality R Dub, is full of archival material and plenty of perspectives from the key players in one of Tucson’s touchstone cultural organizations of the past quarter-century. If you’re wondering why and how a radio station could be so important to so many people, then the corporations have already won.