Talk bout quick exits, TV Column fans! . . .

"Melba," the CBS sitcom starring Melba Moore as the head of "the Manhattan Visitors Center," debuted last Tuesday at 8 p.m. to a dreadful 9.2 Nielsen rating and a 13 percent audience share, almost assuring the show of a spot near the bottom in this week's national primetime rankings . . .

But CBS Entertainment didn't wait for the rankings. Friday the network announced that "Melba" and the 8:30 p.m. follow-on show that night, "Charlie & Co." (he got an 8.2/12), have been pulled off the air until sometime later this spring . . . as of last Tuesday at 9 p.m . . .

The 8-to-9 p.m. Tuesday time slot has been a headache all year for CBS, starting with "Hometown." The temporary replacement for the two sitcoms will be "Trapper John, M.D.," who returns with a new episode the night of Feb. 18 . . .

Meanwhile, tomorrow night President Reagan's State of the Union address and the Democratic response will preempt that hour anyway. On Feb. 11, CBS will fill the time slot by repeating a couple of Valentine's Day specials starring Bugs Bunny and Charlie Brown . . .

And on Feb. 25th, CBS preempts the whole Tuesday night lineup for the annual Grammy awards . . .

Six episodes of "Melba" had been ordered. With one already gone and three others completed, production will continue on the other two . . .

"Charlie & Co." has used up 14 of its 18 ordered episodes. One show remains to be taped, according to CBS . . .

The announcement Friday that NBC News has dropped plans for its own 24-hour cable news service because of limited response from cable system owners, was no surprise to the industry . . . or to NBC News President Larry Grossman, who has never given the project better than a 50-50 chance, at least in public . . .

NBC had set a goal of 13.5 million potential subscribers (the minimum amount required by A.C. Nielsen to make its ratings surveys) before it would launch the service. An original December deadline to reach that number was moved up to Jan. 31 . . .

For the record, NBC said Friday it had signed with cable systems representing about 3 million cable TV homes (of the total of 38.9 million TV homes wired for cable around the country) . . .

But insiders suggest that cable operators representing twice that number of subscribers had informally agreed to sign with NBC if the network had been closer to its goal . . .

Aggressive salesmanship from a suddenly alarmed Cable News Network is credited with slowing the NBC effort . . .

However, NBC News is not dropping the cable news idea entirely. Down the road, there's a chance that a limited cable news service could be introduced on an existing cable network offering specialized information (financial, health, weather, etc.) to give NBC a leg up in the field, which it still believes has possibilities . . .

A suit was filed last week in D.C. Superior Court against Capital Cities/ABC Inc. by Michele E. Shepherd, a graphic arts designer with the ABC News bureau here, and LaRue Graves, a former free-lance employe in the same department . . .

The suit also names Kenneth Dyball, manager of the bureau's graphic arts division, and George Watson, chief of the Washington bureau . . .

Both plaintiffs, who are black, allege they have been "subjected to unlawful discrimination and retaliation and to intentional infliction of emotional distress in regard to their employment at ABC, in violation of the D.C. Human Rights Act of 1977 and the common law of the District of Columbia" . . .

The plaintiffs seek $10 million in damages plus $20,000 from Dyball and $150,000 from Watson. Attorneys Linda Huber and Mark Lane represent Shephard and Graves . . .

The network refused comment on the suits last week . . .

Shepherd has been a full-time employe of the bureau since September 1982. Graves claims he was wrongfully dismissed last November after nine months of employment following his attendance at a meeting of minority employes . . .

Also in the News

The Senate is expected to begin debate today on whether to approve coverage on a test basis of its sessions on television . . .

Sen. Robert Dole (R-Kan.), who had been lukewarm to the project in the past, recently said he hoped a "responsible package" could be put together "in short order" . . .

ABC's "Nightline" will feature a live one-hour debate Wednesday night between Philippine President Ferdinand E. Marcos and his opponent in Friday's election, Corazon C. Aquino . . .

Channel 7 News Director Tom Doerr continues to shake up the news operation . . .

Bob Reichblum, who had been executive producer at WDIV in Detroit, has been named assistant news director for daily news, in charge of the assignment desk, general assignment reporters and staff . . .

Penny Mickelbury has been named assistant news director for specialty units and special reports, including "Seven on Your Side," Seven's investigative unit, medical reporting and planning for sweeps special segments . . .

Executive Producer Mike Crew is in charge of producers, writers and production assistants and news operations manager Roger Hommel is in charge of photographers and video editors . . .

Seven has also signed Jeff Rose, a photographer, and reporter Gail Pennybacker, both from KTUL in Tulsa (like WJLA, an Allbritton Communications station); medical reporter Marilyn Mitzel, from WTHR in Indianapolis; and general assignment reporter Kathy Wolff, from WFTV in Orlando, Fla. . . .

Signed as writer/producer were Brian Jones of WWL in New Orleans and Shelly Harper, from KTVY in Oklahoma City, another Allbritton station . . .

Doerr is still looking -- probably from within the station -- for an 11 p.m. news producer and has named Geoffrey Roth as 6 p.m. producer. Rob Allman and Linda Ring produce the new 5 p.m. news . . .

His night assignment editor and 11 p.m. producer both recently defected to Channel 4, following former WJLA news director Kris Ostrowski, now deputy to Four's news director, Jim Van Messel . . .

Incidentally, early reports on viewership for Seven's revised early evening schedule are good, but last week was an unusual news week and it's probably too early to get a firm reading on performances of either the 5 p.m. news, the "ABC World News Tonight" at 6:30 experiment, and "Jeopardy!" at 7 p.m . . .

Catching Up With CBS News: Harry Radliffe has been promoted from producer at the London bureau to London bureau chief. His deputy will be Anthony Streuli . . . who has been at the CBS News Washington bureau since 1972 as a producer . . .

Radliffe, incidentally, was an assignment editor in the mid-1970s at the ABC News Washington bureau. He replaces Mark Harrington, who has returned to New York as a News vice president . . .

Assistant CBS News Los Angeles bureau chief Leroy Sievers has been named temporary bureau chief in L.A. Next year, Jennifer Siebens, now Paris bureau chief, will take over in L.A. after a maternity leave . . .

Oh, by the way, somebody at CBS News neglected to tell C. Airwaves that Betsy Ashton has signed a new contract to stay with "Morning News." However, she will appear only once a month or so, instead of twice a week, as in the past, now that Erin Moriarity has been brought in from Chicago to be regular consumer reporter . . . Ashton, as reported, continues as WCBS consumer reporter . . .

Geraldo Rivera has signed to host the live syndicated special in April that will show an old hotel safe in Chicago, purportedly used by gangster Al Capone, when it's opened for the first time in 50 years or so . . .

And Finally sw,-2 sk,2 ld,10 Broadcasting magazine says Martin Rubenstein, chosen Friday to be the new president of the Corporation for Public Broadcasting, will receive $86,200 annually . . .

Rubenstein, 50, who was president and chief executive officer of the Mutual Broadcasting System when he left MBS in 1984 after five years, has most recently been a communications consultant here . . .

Broadcasting says FCC review board member Norman Blumenthal suggested the job to Rubenstein several months ago and put him in touch with public broadcasters who were searching for a successor to Edward Pfister. Pfister left CPB last May after a series of run-ins with CPB Board Chairman Sonia Landau . . .