BANGOR, Maine (AP) _ Seven nuclear arms protesters convicted of criminal trespass at the Maine Air National Guard base were let off the hook without fines by a judge who praised their motives.

Superior Court Justice Bruce Chandler unconditionally discharged the seven demonstrators Friday, meaning that they will have criminal trespassing convictions on their records but go free and pay no fines.

''I recognize that these defendants were espousing a cause which ... a great many Americans - at least I hope this is true - agree with,'' Chandler said.

He said the protesters violated the law because they ''felt some action had to be taken'' to bring the danger of nuclear arms to public attention.

The case stemmed from an August 1984 rally at the National Guard base during which the protesters, after informing authorities of their intentions, crawled under a gate onto the base and were arrested.

The four women and three men were originally fined $250 each, but they appealed the case to the state Supreme Court. In a decision handed down last month, the high court upheld the convictions but not the fines and remanded the case to Penobscot County Superior Court for resentencing.

In a hearing last week, one of the protesters handed Chandler a newspaper clipping about 12 West German judges who, wearing their judicial robes, blockaded the entrance to a military base to protest the presence of nuclear weapons in their country.

Chandler, displaying the news clipping on Friday, said he had referred to it often while deliberating on the sentence.