Ed Weinberger looks scruffy and disheveled, but then, he has just spent an entire night chasing a monkey up and down the steps of the Lincoln Memorial. Actually, as he is quick to correct, it is not a monkey but an orangutan, the star of the new NBC comedy series "Mr. Smith," premiering tonight at 8 on Channel 4.

"Mr. Smith" sounds like the silliest new program of the year, and that's saying something, but this ape comes with a pedigree that is strictly prestigioso.

Like Stan Daniels, the other executive producer of "Mr. Smith," Weinberger helped write and produce two of the best and most "adult" comedies in TV history, "Mary Tyler Moore" and "Taxi," as well as the short-lived but long-witted ABC series "The Associates." So why are guys such asthem horsing around with an orangutan? And a talking one at that--because the premise of the show is that, thanks to a laboratory gaffe, Mr. Smith can talk, has an IQ of 256, and works on government research in the nation's capital (that last part isn't too hard to swallow). Is this another sign of how far TV has sunk, or what?

"I know, I know, it sounds like something Fred Silverman might order you to do," says Weinberger, wearing a yellow slicker and half-on, half-off yellow socks. "But it's not. I thought it would be fun to do. I don't want it to be anything less than anything I've ever done. In fact, I want it to be more so because of the eyebrows that are raised when people hear the premise.

"This started out as an idea of mine in a way where I kept saying to people, 'Talk me out of it, 'cause it's a stupid idea,' and Jim Brooks another MTM and 'Taxi' veteran , who I expected to be enormously cynical about it, really couldn't be as I began to explain the kind of things I thought we could do with this show. The premise is only that we have a fable character, a fantasy character, but the world he's in is as real as any 'Mary Tyler Moore' world or 'Taxi' world or 'Barney Miller' world, but it's only this creature who, in an exotic mistake in some fashion, this happened, and through this creature now we enter the real world and see things differently and he sees things differently and therefore the set we had built . . ."

Weinberger continues on with this sentence, if it is a sentence, almost into eternity. He is known in Hollywood as a guy who never puts in periods when he talks, which is strange because in official credits he likes to put a period at the end of his first name: "Ed. Weinberger." He says, "That's just an affectation. It's cute or boring, depending on how you feel about me." When he was 7, and suffering under the name of Edwin, young Weinberger shortened it to Ed and put a period after it because he thought it was an abbreviation, like Pa. for Pennsylvania.

As for "Mr. Smith," while Weinberger concedes "it's not a classy genre, the talking animal show," he says it harks back farther than "Mr. Ed" all the way to "Aesop's Fables." He thinks America will laugh with it, not at it. "I haven't lost any sense of what I think good television should be," Weinberger says. "Or good comedy, anyway, and that's good relationships, good stories, intelligent stuff that doesn't look down at its audience. Somebody should just run over me with a truck--no, that sounds like Valley Girl talk--somebody should castigate me if I don't maintain these things."

The star of "Mr. Smith," C.J. the orangutan, previously appeared in the Clint Eastwood movie "Any Which Way You Can" and with Bo Derek in that ridiculous remake of "Tarzan." Weinberger is crazy about his leading man. "It's a Buddha-like presence," Weinberger says of him. "He has wisdom about him. You have to know the animal; I'm in love with him. I'd have him in my house any time." He didn't have to audition ape upon ape for the role, Weinberger says. "Fate brought us together right from the start."

He considers C.J. a consummate professional--one who earns $11,000 a week for his work, with a contract guaranteeing increases if the show is a hit. C.J. has an agent who gets a cut and certain expenses. Weinberger says more retakes have to be filmed because of mistakes made by human actors than because C.J. didn't walk over to the right mark on the floor. Weinberger was hoping to keep it a secret, but the voice of Mr. Smith heard on the soundtrack is his own rumpled baritone. That is, Weinberger's own, not C.J.'s.

Although when it's all over, we may believe that a monkey can talk.

Weinberger is very evasive on the topic of how they make it look not only like monkey see and monkey do, but monkey gab. Told of reports that a double in a monkey suit was doing some close-ups, Weinberger would only say, " 'Double' ain't the right word. It ain't a man in a suit. It's nothing in a suit." He says the National Enquirer has tried sneaking onto the set to find out how it's done, but he hopes to maintain strict secrecy. "Look, we all know he doesn't really talk, or else we'd have an easier show," Weinberger says. "It's like 'E.T.' To get these effects, you have to do some tricks."

Going on location to film sequences for a situation comedy is very unusual because it's very expensive. "I'm trying to go first-class," Weinberger says, explaining the trip to Washington. "I'm pushing a studio Paramount that doesn't want to spend a cent of money, doesn't understand the show, and the same thing with the network, but I'm saying to them, at least until the audience decides, I'm not going to do it any other way."

He guesses the network bought the show sight unseen because it's what's called "high concept"; it has a one-two punch that can be summarized in a snappy sentence. But Weinberger says this won't be the typical gimmick show. The title is a bow to the trail blazed by "Mr. Ed," he says, but the famous talking horse ("a-heh, a-heh, a-heh") didn't "really" talk. "You had to go down to the barn to him, and he just wiggled his mouth up and down and he talked funny, in what I guess you'd call animal stereotype," Weinberger says. "This was before animal liberation; they all had the same funny way of talking, like they all had the same Hanna-Barbera voice coach. What we're saying is that an animal can have a character, he can have a personality, he can have some wit and he can have some insights and he can have some compassion and he doesn't have to just whisper in Donald O'Connor's ear."

Donald O'Connor's ear was whispered into by Francis the Talking Mule, fairly successful in the movies early in the '50s. On TV, while Cleo the sarcastic basset hound was a big fave on "The People's Choice," and while talking Morris has sold a lot of 9-Lives cat food, the monkey per se has generally been Nielsen poison, from "Me and the Chimp" to "B.J. and the Bear" to "Planet of the Apes" to "The Hathaways." It remains to be seen if Mr. Smith can salvage the tarnished image of the TV ape. If so, the floodgates will open, and every show will have a monkey. Actually, many programs featured an orangutan, C.J. himself or some stunt ape, on episodes last year.

Weinberger says he is also concerned that Mr. Smith be treated humanely by his trainer. "We had a famous dog on a 'Taxi' once and asked him to do something and the trainer says 'Okay' and they took him backstage and they were whipping the s--- out of him! I got ill! I said, 'The hell with it--they did this to that dog? They're slapping that dog around?' It was like the flag, you know, in a way."

The sequences shot at the Lincoln Memorial, the Jefferson Memorial and the White House are not played for laughs in the show, Weinberger says. He based the sequence on the part of Frank Capra's "Mr. Smith Goes to Washington," in which Jimmy Stewart first tours the nation's capital and gets misty at its patriotic symbols. Weinberger even brought a story board of that sequence, arranged neatly on Polaroids in a little album, with him to Washington for the filming.

Weinberger says he likes the idea of doing an "8 o'clock show," which traditionally means a family-aimed comedy. "Obviously, to have an orangutan is to have an appeal to children. I'm not against that. I haven't had too many shows that children watch. It's been the downfall of some of those shows." For Weinberger, getting to know an orangutan in the course of doing this show has been a fulfilling and enriching experience. "When I watch him sometimes, I don't know what he's thinking, but he's thinking a lot more than he's given credit for. I went in one morning to his motor home and they were playing around with him and tickling him. Now he has every single human gesture; he's trying to get your hand away at the same time he's chortling inside about it. It's just the same reaction that we all have, and his mouth is opening and he's about to form a laugh--but he can't. He's about a million years from a 'ha ha.' That's all, just about a million years. It's not so much eerie to see that as just a wonderful sense of our interdependence and our connection with each other, and that, to me, is reverential more than anything."

He hopes the TV audience by the tens of millions will want to share this relationship. "Let anybody sit back and say, 'Oh, we're getting a talking orangutan this year, along with a genie in a bottle, a ghost that comes back,' and I'll let that stand until we go on the air and then I'm prepared to take my chances," Weinberger says. "Certainly," he says of his new program, "I pray to God it ain't gonna be what people expect it to be."