Quick, disconnect that thingamabob or we'll all be blown to itsy-bitsy pieces! Whew, that was close. Now, on to the next boobytrap. "Don't tell me you know how to make a bomb out of a stick of chewing gum," cracks the lanky scientist, to which MacGyver, the hero of "MacGyver," ABC's new action series, responds, "Why -- you got some?"

MacGyver, who like ABC's "Spenser" has no first name, specializes in low-tech improvisations for averting major and minor catastrophe. In the first minutes of the series premiere, tomorrow night at 8 on Channel 7, the free-lance do-gooder defuses an armed missile with a paper clip. Later he descends into a burrowing inferno to rescue two Nobel-nominated scientists, and accomplishes the mission with the help of a pack of cigarettes, a broken pair of binoculars, a cold capsule, a chocolate bar, a loaf of bread, a jug of wine (no, wait, how did those get in here?) and his own brand of creamy cool-hip.

Let's see now: A bomb blast has wracked a top-secret underground research installation, sulfuric acid is leaking into the Rio Grande, the ultimate doomsday weapon is threatening to unleash chain reactions in the ozone layer, and it's 6 minutes until a cold-hearted coven of military bureaucrats (shades of "Rambo") launches a missile that will blow MacGyver and his paper clips into teeny-weeny pieces.

Sadly and stubbornly enough, even with all this happening, "MacGyver" is about as thrilling to watch as a seventh-grade shop class making bookends for Father's Day. In the MacGyver role, Richard Dean Anderson certainly fills the bill to overflowing. He's molto primo hero. MacGyver's not only a cool character but a caring character, according to the script. He likes to play basketball with a little black kid from the neighborhood. That's to show us his heart's in the right place; apparently the producers don't mind that the black kid, like the youngster of ABC's "Webster," is being treated primarily as a prop and a pet.

"I'm sort of a repairman," MacGyver says, but likable as Anderson is, and despite a briefly zippy laser show in a bombed-out corridor, the program chokes on its own cutes. Actor Henry Winkler and director John Rich are the executive producers; the premiere was written by Thackary Pallor and directed by Alan Smithee. A better mousetrap they did not build. 'Amos'

"Amos" almost rhymes with "shameless," which this CBS Sunday Night Movie, at 9 on Channel 9, certainly is. Ostensibly a problem drama concocted to focus attention on mistreatment of the elderly in nursing homes, the film degenerates quickly into a lurid potboiler about a homicidal nursie who has appointed herself grim reapette to a small band of cowering old-timers.

It's Kirk Douglas, as Amos, to the rescue, except that Kirk ought to be embarrassed to appear in a TV movie that so mimics his producer son Michael's film hit "One Flew Over the Cuckoo's Nest." Kirk has more or less inherited Jack Nicholson's role for this imitation. The Nurse Ratchett of the piece is played by Elizabeth Montgomery, who still looks bewitching after All These Years. Director Michael Tuchner doesn't want to take any chances, so the first shot he gives us of Montgomery has her slipping into her silk lingerie. That's supposed to tip us off she is not an angel of mercy. And to show us her legs, of course.

Richard Kramer's script is one of the stickiest pieces of treacle to be seen on these shores since the Gish sisters were still in ringlets. Unbelievable! He alternates between weepy heart-tugger old-codger scenes and hysterical malevolent chicaneries perpetrated by the nurse or her oafish henchman, to whom the team of Bela Lugosi and Dwight Frye was the height of subtlety by comparison.

Kramer has to get 78-year-old Amos committed quickly to the evil Sunset Home, but he inadvertently blunts our sympathies in the process. Amos recklessly drives a car through a stop sign, killing his wife, who was in the passenger's seat, and crippling himself. This would be a good setup for a movie based on the "60 Minutes" segment about how some old people should not be allowed to keep their driver's licenses but do anyway.

Once Amos gets put away, he is subjected to numerous tortures, but the worst has got to be finding out that Ray Walston is in the next bed at Sunset. This guy can chew scenery even when doing voice-overs. Amos wises up to the naughty nurse's skullduggery, but the screenplay requires him to make foolishly reckless accusations so as to precipitate preposterous confrontations. These build to a shaky climax involving a specious excuse for martyrdom.

"Amos" is wide-open specious from beginning to end.