Johnson stars in TV's hottest cop show. He's made baggy linen jackets and the stubbly-mug look the fashion rage of the '80s. Now he's trying to scale the pop-record charts with a solo LP (Epic). If he succeeds, Johnson will owe a debt to the rocking backup band he and producer Chas Sandford assembled for this session. The group includes Ron Wood, Stevie Ray Vaughan, Bonnie Raitt and Michael Des Barres, and they add a lot of oomph to Johnson's sometimes soft-bellied pop-rock style. Willie Nelson drops in for a little harmonizing on the Bob Seger ballad Star Tonight. Johnson, who says he grew up singing in his grandfather's Pentecostal church in southern Missouri, has a pleasant enough voice. He's even got enough chutzpah to hold his own in the two duets he performs with 15-year rock veteran Raitt, including Tom Petty's Lost in Your Eyes. If Johnson's glittering supporting cast fails to get him into the Top 10, he can no doubt count on heavy TV play of his video version of the Heartbeat single to give his album a boost. Fellow Missourian Al Corley, however, seems to have the deck stacked against him on his second LP (Mercury). His weekly TV exposure went out the window four years ago with his Dynasty character, Steven Carrington. More to the immediate point, he doesn't have any monster musicians on hand to cover the fact that he has no discernible vocal talent. It's ironic that an LP called Riot of Color should feature a singer who can't venture beyond lifeless monotones. Julia Dawson's harmonica playing on Havana Blue is the only warm spot. Corley's first album, unaccountably, was a huge hit in Europe. This LP is pretty well summed up in the title of its fourth cut: Waste of Time.