FIRST THEY TOOK away the organ music. Now - at the theaters here and in Philadelphia - they're taking away the cameras. The soap opera is going "legit."

In the theatrical circles, the soaps are the illegitimate children of the legitimate stage. But they also pay the bills for plenty of stage actors. And they reach a huge audience of people who seldom go near a stage. It's rather embarrassing.

ASTA Theatre, though, is not embarrassed. The stage folks there are seizing the suds for their own purposes. In one stroke, ASTA is introducing live soap opera and lunch-time theater to Washington, and throwing in a political edge to suit the city.

It's called ". . . and the Pursuit of Happiness," and beginning Friday it will depict the lives and loves of a band of Washingtonians every Monday, Wednesday and Friday - two performances a day - at ASTA's Capitol Hill home.

The form is genuine soap opera: half-hour installments of a continuing serial, complete with commericals. It comes on, so to speak, in the middle of the working day, at 12:15 and 1. Nine-to-fivers who harbor secret yearnings to watch the soaps can do so without commandeering the office TV set.

The action will be more sustained than on TV, for there will be only two commerical breaks, and they will be live, too. You won't be able to do the ironing while you watch, but presumably talking back to the set will be easier (if not exactly encouraged) when the set is the space you're in, not the box you're watching.

Though no TV trays will be provided, viewers are encouraged to eat. Homemade box lunches will be available across the street at Townhouse Restaurant. Regular TV-watchers might find it expensive - $2 for the show and $1.50 for the Townhouse lunch - but theatergoers will disagree.

The scripts are closer to "Mary hartman, Mary Hartman" or "Soap" than they are to "As the World Turns." And this being Washington rather than Fernwood, the dominant force in the city is The Government, not The Plant. While ASTA's show will not be a satirical revue, political comments and references go with the territory.

The main characters:

Heather Mason (played by Cynthia Dene Nash), who has just arrived in town to get a PhD in philosophy and be a teaching assistant at Georgetown University. According to the summary of the characters prepared by the creators of ". . . and the Pursuit of Happiness," Heather is "pained by D.C.'s refusal to fit philosophical systems."

Doug Raddatz (Charles B. Clapsaddle), a third string investigative reporter by day and a would-be club singer by night.

Grace Tenniel (Caron Tate), a young City Council candidate and former city bureaucrat.

Ben Eisenhower (Fred Strother), an ambitious' aide to an exceedingly corrupt House member. His kid brother will arrive from down South later in the summer.

Mary Anne Leland (Maureen Kerrigan Sheehey), an ex-State Department wife, now remarried to a caterer and the manager of his business.

Taylor Leland (Stoney Richards), the caterer, also a tennis pro and a closet epic poet, slightly Southern.

Claire Carrigan (Barbara Burke), Georgetown matron/artist "torn between true art, as she sees it, and good taste - as she sees it," according to the summary of characters.

Rod Carrigan (Jim Ward), a manipulative psychiatrist and lecherous bar owner, "California mellow."

Heather, Doug, Ben and Grace share a house next door to Mary Anne and Taylor. Doug, Ben, Heather and Taylor are patients of Rod. Ben and Grace are ex-lovers - she broke it off. They're black, too. Heather wants Doug, who wants Claire, who wants Taylor, who isn't sure he truly loves Mary Anne. Rod wants everyone except Ben and Taylor. "Well, maybe Taylor, too," adds the summary of characters.

The main sets are the living room shared by four of the characters, the kitchen shared by Taylor and Mary Anne, and Rod's bar. Plot synopses will be distributed each day with the menu. For those who can only drop in once a week, there will be Monday story lines, Wednesday story lines and Friday story lines.

". . . and the Pursuit of Happiness" was inspired by "Center City Soap," a theatrical serial that recently began sudsing away the lunch hour in a Philadelphia storefront. Celia Ribando and Christine Brim, sisters who run a scripting enterprise here called Washington Motion Picture Properties Inc., heard about "Center City Soap" and, they say, instantly thought of adapting the idea to ASTA. Dona Cooper, ASTA's artistic director, says she "bought the idea hook, line and sinker within hours" after Ribando and Brim presented it to her.

Ribando and Brim are writing the scripts in between their other, more lucrative projects (which are generally training films on such topics as weather stripping windows). Cooper is directing. The actors, cast from 140 who auditioned, come from backgrounds in dinner theater, small theater, summer stock, commercials, radio and modeling. ASTA and Washington Motion Picture Properties will split slightly less than half the take, with the rest divided among cast and crew.

The three creative partners complement each other well. Cooper is down-to-earth, stage-smart (from the evidence seen at a recent rehearsal) and comes from a conservative Republican background in El Paso. Besides her off-hours theater work, she has been a Hill staffer and, long ago in 1968, a receptionist at national Nixon headquarters. ASTA, compared to New Playwrights' Theater, its former partner, "has been fairly staid," she says, and she hopes the soap might change ASTA's image.

Brim is willing to do her share to change ASTA's image. "There will be no one who won't in some way be offended," she says. Brim has been public relations director for the National Abortion Rights Action League, and a reporter. She'll tell you anything you want to know about the "literary antecedents" of her work. "The show is a smorgasbord of comic styles," she says, "with the rhythms of farce and the substance of satire." She even refers to the zeitgeist symbolized by a big ball of red tape that the cast may use in publicity stunts and guerrilla theater events. And then there's the possibility of videotaping the show, bringing us back full circle to TV. Brim overflows with ideas.

Ribando, 5 years older and quieter than Brim, is an actress and former teacher as well as a writer. She has been conducting a "showcase" performance at ASTA completely separate from her soap work. But she contributes her share to the scripts, judging from the bright and balanced dialogue the two sisters conduct when you get them talking.

With one breath, Brim can say she sees the show as "a collective Scheherazade, telling stories for a thousand and one nights." In the next breath, she says there are no plans - yet - to continue the show beyond August. "And in a week or two, we'll probably still be doing scripts on electronics training," Ribando adds.

But Cooper and company are convinced this is the right city for lunch-time theater and for their type of show. There are plenty of commuters here who would prefer to go to the theater in the daytime, they predict. And material can be practically clipped right out of the headlines in such a political town.

"Political people have been encroaching into the theater world for years," says Brim. "There's no reason the reverse can't be done."