Negotiators for striking television and film actors yesterday reached a tentative contract agreement with producers that could signal the end of the nine-week walkout.

Executives at all three networks yesterday agreed that most of the long-delayed new fall TV schedule could be in place by the last week of October or first week of November, if no further serious hitches develop.

However, at least two major obstacles remain in the path of a quick resumption of full production of TV shows and movies -- speedy ratification of the agreement reached early yesterday and how the various unions involved would respond to picket lines that could be thrown up at the studios in Hollywood by the still-striking American Federation of Musicians.

Although a spokesman for the Screen Actors Guild and the American Federation of Television and Radio Artists said ratification of the pact by their combined membership of 67,000 could take place within two weeks, several leading members of the guild, including Ed Asner, have already expressed their opposition to approval of the new contract.

Asner, the star of "Lou Grant" and a spokesman for the hard-liners in SAG, said yesterday he would vote against the contract because "the proposals for minimum wages and residual payments are inadequate and meaningless."

In addition, the musicians have backed the actors during their nine-week layoff and many have previously expressed reluctance to cross AFM picket lines at studios should they be subsequently set up.

However, the new contract contains a no-strike clause, making it illegal for actors to honor another union's picket lines.

One network executive yesterday said that he felt "the bulk of the actors want to get back to work and won't support the musicians. The key may be the below-the-line' unions, like the Teamsters, who have been out of work because of the strike, but which have a history of respecting picket lines."

SAG and AFTRA agreed to a proposed three-year pact early yesterday after an 18-hour bargaining session.

The key issue settled in recent days was a wage package that calls for a 15-percent boost in minimum salaries for the first 18 months and another 15 percent for the second 18 months, adding up to a 32.25 percent boost for the life of the contract, according to negotiators.

Originally, the actors had demanded a 35-percent raise the first year with no raises during the rest of the pact. Their old contract called for a minimum $235 a day or $785 a week.

Earlier, the actors had agreed to a complex formula guaranteeing them revenue from home video sales of TV and movie productions.

Network sources yesterday said that the musicians' strike probably won't affect production of the new TV programs. Producers are free to use theme music already recorded for holdover series and will probably rely on outside-the-country musical groups for any additional needs.

Robert Daly, president of the CBS Entertainment Division, said yesterday that "if everything goes smooth, we should be introducing our taped series [such as 'Alice', 'The Jeffersons,' 'One Day at a Time' and 'Archie Bunker's Place'] starting the week of Oct. 27.

"It will probably be late November for our film shows, like 'Magnum P.I' and 'Freebie and the Bean,' because they have a delay in the labs."

Daly said that the first new episodes of "Dallas" should appear "close to the first week in November" since Lorimar Productions had shot portions of the first nine episodes before the strike hit July 21.

The CBS executive said that the debuts of some of the new series could be delayed in November depending on what rival networks put in the schedule.

"We're not going to throw new product up against 'Jaws II,' you know."

Daly seemed optimistic despite the threat of possible delays, posed by still-dissatisfied strike leaders.

"There's a tremendous desire to go to work on the part of everybody," said Daly. "A lot of people have lost a fourth of their yearly income."