SITCOM-ITIS RAMPANT ON CABLE TELEVISION

What’s new on cable TV this season is what’s old on regular TV--first-run sitcoms.

Breaking its tradition of airing only comedies that are antique network reruns, USA Network, for example, is premiering its first original sitcom (8 p.m. Wednesdays starting Oct. 2), with Don Adams starring as a supermarket manager in “Check It Out.” It’s based on the English series, “Tripper’s Day.”

“1st & Ten,” a dreadful slug of a comedy about a professional football team under female ownership, has already begun a 12-week run on HBO. And “Washingtoon,” an amusing political satire based on a cartoon strip, is already under way on Showtime.

Nowhere on cable is sitcom-itis more rampant than at Atlanta super station WTBS, which last Monday added a third original sitcom to its schedule and is stockpiling others. The newcomer is “Rocky Road” (4 p.m.), a silly and seldom funny trifle about a brother and two sisters trying to survive as owners of an ice cream parlor they inherited from their parents.

In the sort-of-old/sort-of-new category--and no trifle--is “United States,” Larry Gelbart’s highly creative and rewarding series about a middle-class couple, well played by Helen Shaver and Beau Bridges. Sunday at 5 p.m. and 9 p.m., the Arts & Entertainment Network begins showing eight episodes that aired on NBC in 1980, followed by five others that have not been seen.

Elsewhere, “Danger Bay,” an adventure series about a trouble-shooting veterinarian and aquarium curator, comes to The Disney Channel (8 p.m. Mondays starting Oct. 7). Disney is also unveiling a weekly talk show hosted by pop psychologist Joyce Brothers in November.

And another weekly talk show, “Dick Cavett, USA,” (10 p.m. Mondays starting Sept. 30) bows on the USA Network which, continuing its pursuit of the different and imaginative, has designated the same day to launch new episodes of the game show, “Jackpot.”