Brian Wilson's genius has been the source of most of the Beach Boys' triumphs; his personal problems have been the cause of most of their disappointments. After years of relative inactivity, Wilson made a strong comeback on the 1977 "The Beach Boys Love You," though it was ignored. He was hardly present at all on the last year's embarrassing "Light" album. Now he's back as a large presence on "Keeping the Summer Alive" (Caribou EZ 36283), though he still hasn't recovered his creative peak of 1965-68.

When Wilson and subsequently the Beach Boys -- who perform here Friday -- lost their confidence in the '70s, their fabled production polish corroded badly. Songs were thrown onto albums with off-key vocals left in and with simple instrumentation rather than the usual Spector texture. Ex-Beach Boy Bruce Johnson returned to the family last year, and he has produced the new album till it positively gleams. In fact, "Keepin' the Summer Alive" is the most commercially appealing Beach Boys album in more than a decade.

The album's best track is the first single: "Going On," Wilson's confessional about picking up the pieces after his divorce. He creates a capitivating dynamic by pitting a lush, highpitched choir against his brother Carl's gusty lead vocal. The choir treats the theme of breaking up with the melodic optimism of teen angles, but Carl counters with desperation of an adult whose been through too many breakups. These adolescent and adult approaches alternate verse-by-verse, then line-by-line and finally phrase-by-phrase, building to a powerful conflict.

The rock 'n' roll songwriters who have remained creative into their middle age have all wresteled with this conflict between adolescent hope they don't want to lose and the adult desperation they can't ignore. Brian Wilson expresses the conflict musically, while Neil Young, Bob Segar, Ray Davies and Jagger-Richards express it lyrically.

Wilson's other contributions are worthy but familiar vairations on things he's done before. "Some of Your Love" is yet another upbeat summer song sung by Mike Love. It breaks no new ground, but it bursts with such joy it could be a single if given the right push. Wilson completely transforms Chuck Berry's "School Day (Ring! Ring! Goes the Bell)" with an a capella nursery rhyme tacked on the front and substituting vocal syllables for the rhythm guitar. "Oh Darlin' is a pop ballad distinguished by triplet harmonies behind Wilson's 4/4 lead vocal.

Bruce Johnston's "Endless Harmony" starts off with hackneyed tribute to the Beach Boys, but the song ends with the richest harmony singing you're ever likely to hear. The same is true of "Santa Ana Winds," which begins with Al Jardine's tribute to California weather and ends with Wilson's evocation of that weather. Carl Wilson wrote the title tune with Randy Bachman. His best composition in years, "Keeping the Summer Alive" is a rollicking rhythm & blues with half a dozen vocal parts ricocheting throughout. rLove sings bass notes as if they were depth charges; a younger Stevie Wonder.

Another Carl Wilson-Randy Bachman tune, "What's Your Hurry Darlin'," shows up on "Everything is Grey" (Scott Brothers SB 7108) by Ironhorse, Bachmans new quartet. Ironhorse is less like the heavy metal of Bachman's old group Bachman Turner Overdrive, and more like the pop-rock Bachman's older group, the Guess Who.

"What's Your Hurry Darlin'" is the strongest composition on the album, with an appealing melody and clever harmonies. Unfortunately, Ironhorse lacks the vocal talent to fully realize the song's potential. The album's other nine songs by Bachman and Ironhorse singer Frank Ludwig are pleasent but underwhelming '60s rock.

"Keeping the Summer Alive" sounds like the early Beach Boys, which is both its strength and limitation. The finest harmony group in American music once again deserves that title. The group that has consistently outdone Phil Spector in the studio once again has that texture. But except for "Goin' On," the new album contains nothing they haven't done many times before.