arner Communications Inc. assistant treasurer Solomon Weiss was convicted today of taking bribes in a 1973 stock scheme involving a Westchester County theater.

A U.S. District Court jury, after four days of deliberation, found the 53-year-old accountant guilty of one count of racketeering and three counts each of perjury and mail fraud.

Weiss faces a maximum of 20 years in prison and a $25,000 fine on the racketeering count. Motions on Weiss' sentencing were scheduled for Dec. 30. Robert Kasanof, Weiss' attorney, said the conviction would be appealed.

During the three-week trial, Assistant U.S. Attorney Nick Ackerman argued that the case would show "high-level corporate fraud." From the trial's beginning, Warner Communications, whose interests range from records, movies and Atari games to the New York Cosmos and whose operating revenues hit $3.2 billion last year, found its name being invoked.

The case began in 1977 when, in the course of an unrelated probe, federal investigators tapped the telephone of businessman Thomas Marson. According to court documents, Marson discussed his connections with the Westchester Premier Theatre in Tarrytown, N.Y.

An investigation revealed hidden investors in the theater, which featured big-name stars such as Frank Sinatra and Dean Martin. The investors, testimony showed, included the late Mafia bosses Carlos Gambino and Frank (Funzi) Tieri, and after the theater's bankruptcy in 1978, several organized crime figures were convicted on charges of skimming receipts.

The federal investigators discovered that in 1973 the theater sought to raise capital through a public offering of 275,000 shares of stock. But when the stock offering fell short of subscribers, Leonard Horwitz, a theater official and a stockbroker, allegedly turned to a friend at Warner to unload part of the unsold shares.

In the Weiss trial, prosecutor Ackerman alleged that the defendant got $170,000 in bribes for inducing Warner to buy 40,000 shares of the theater stock.

Ackerman, in his opening statement, reached to the top of Warner, singling out chairman and chief executive officer Steve Ross. Ackerman told the jury: "You will learn how the chairman of the board of Warner designated the defendant, Weiss, as banker and overseer of a secret cash fund at Warner."

But that was the last mention of any "secret cash fund" in the trial.

Instead, witness Jay Emmett, a former Warner executive, testified that he told Ross the theater was willing to lend Warner the money to buy the stock. Emmett said Ross replied that the company was not permitted by law to take such a loan, and testified that Ross suggested Horwitz should discuss the matter with Weiss.

Emmett, the prosecution's chief witness, acknowledged under cross-examination that he was "the only person in the entire world to attribute the direction of this cash fund to Ross."

Ross, who was not charged in the case, has "unequivocally denied any authorization or participation or knowledge of any secret cash fund."

Kasanof contended during the trial that Emmett and Horwitz had lied to authorities in return for lenient treatment. Both had pleaded guilty in the case last Feb. 10.

Weiss, still a Warner employe earning more than $100,000 annually, testified he owns 41,000 shares of Warner stock worth about $2 million.

The defendant testified he has known Ross about 23 years and is named as a beneficiary in Ross' will. Ross has been described as one of the highest-paid executives in the country.