BACK IN THE LATE '70s, the record industry suddenly discovered the pop potential of hard rock and went after melodic arena-rockers with a vengeance. But times and tastes change. These days, a number of former hit makers have found that their sound is something of a dinosaur.

Somehow, though, Heart has managed to hang on. In fact, the group's new, self-titled album is in many ways its best since "Little Queen." In part, it's because the band has refined its approach, avoiding the old heavy- guitar attack for a balance favoring singer Ann Wilson. But what really put the band back on the charts are the songs here.

"What About Love" is a perfect hard rock hit, a tuneful trifle that blasts its chorus home with punchy power chords. That blend of melody and muscle sets the tone for the album. From the artful anger of "If Looks Could Kill" to the comfortable warmth of "These Dreams," Heart seems finally to have found its formula.

Formula isn't everything, though: Just look at Cheap Trick. This hard-rocking quartet has matched power guitars with a Beatlesque flair for melody for some time now. Trouble is, it just doesn't seem capable of writing songs that live up to that sound.

"Standing on the Edge," the group's latest album, has its moments, especially when singer Robin Zander and guitarist Rick Nielsen hot-rod through such rock basics as "Little Sister," "How About You" and "Rock All Night." But most of the songs here seem too obsessed with craft to matter much as music. It's hard imagining anyone falling for this trick.

HEART -- "Heart" (Capitol ST 12410).

CHEAP TRICK -- "Standing on the Edge" (Epic FE 39592); both appearing Saturday at the Merriweather Post Pavilion.