More than 40 reporters, writers and assistant directors at television station WDVM (CBS-Channel 9) went on strike just before the station's scheduled 5:30 p.m. newscast yesterday, forcing management personnel to put together a hastily prepared and shortened news presentation.

A spokesman for the strikers said the walkout came after an impasse in current contract negotiations with management over pay scales for eight off-camera job positions.

Viewers tuning into WDVM for the news found the first half-hour from 5:30 to 6 p.m. filled with a showing of "Candid Camera," followed by a shortened newscast presented by several management and supervisory personnel whose faces were not familiar to viewers. They made brief announcements about the strike, saying regular program schedules would be maintained "in the public interest."

Meanwhile, several well-known television figures - reporters Bruce Johnson, Pat Collins, Susan King, and Mike Buchanan, anchorwomen Maureen Bunyan and J. C. Hayward, sports-caster Glenn Brenner and weatherman Gordon Barnes among others - were outside the WDVM building at 4001 Brandywine St. in upper North-west, walking a picket line with fellow members of the American Federation of Television and Radio Artists (AFTRA).

Collins, acting shop steward and a member of the AFTRA contract negotiating team, said members of the union voted to strike about 5 p.m. after rejecting what he said was a final offer by management on pay scales for two writers, three assistant directors and three part-time directors.

Management's offer, Collins said, "would not give those eight positions "parity pay" comparable to salaries for the same positions at other TV stations in the area.

Strikers on the picket line last night said top salaries for writers at WDVM are currently about $17,500 and about $11,700 for assistant directors.

Collins said employes in the eight positions would receive a combined total of about $25,000 less than a comparable number of employes at other TV stations over the life of the three-year contract proposed by WDVM management.

Management representatives would not discuss details of the negotiations, but Ed Pfeiffer, WDVM general manager, agreed there was a dispute over pay scales for the eight positions.

Several strikers stressed that the eight positions - seven of which are currently filled - are off-camera jobs, paying far less than the more visible and glamorous on-camera jobs. WDVM's approximately 35 reporters and anchor men and women, whose salaries reportedly range from $30,000 to $150,000, "wouldn't benefit one penny" from any settlement in the current dispute, Collins said.

He said AFTRA management met three times Monday and twice yesterday, with management making its last offer on the eight positions at about 4 p.m.

While the strike occurred suddenly, management apparently was prepared for it. Pfeiffer said the evening news cast was handled not only by supervisory personnel at WDVM but by management employes brought in from other stations owned by WDVM's parent firm, the Evening News Association, publisher of the Detroit News. The Evening News Association owns stations in Oklahoma City, Tucson and Mobile.

Both Pfeiffer and Collins said no new negotiating sessions have been scheduled. Collins said AFTRA will maintain a picket line at the station from dawn to midnight each day until the issue is settled. CAPTION: Picture 1, Newscasters, from left, Glenn Brenner, J. C. Hayward and Gordon Barnes walk picket line outside WDVM. By Joe Heiberger - The Washington Post; Picture 2, WDVM editorial director Rich Adams anchors the 6 p.m. news during walkout by AFTRA members.