A Calvert County Circuit Court judge upheld the conviction yesterday of landlord-professor Shao Ti Hsu on numerous weapons, assault and housing code violation charges, but eliminated a jail term, fining Hsu $3,350.

Hsu, 65, a controversial Washington-area landlord and University of Maryland engineering professor, had been sentenced in Prince George's County District Court in 1980 to eight months in jail and fined $5,000 on charges that included renting condemned apartments and assaulting a tenant organizer and an 11-year-old boy who refused to pay to use one of Hsu's garbage bins.

"He's an old man, and he doesn't pose a threat to anyone," said Circuit Court Judge Perry G. Bowen, who imposed the fine yesterday. "We've got people in Prince George's selling heroin and getting 30 days. There's a hell of a lot of difference between selling heroin and an old man renting an apartment."

Hsu pleaded guilty yesterday to seven convictions that he had appealed from Prince George's District Court. Hsu was fined $600 for renting apartments that had been condemned as "unfit for human habitation"; $100 for assaulting David DeChant, a tenant activist, and $250 for using a steel pole in that attack, which occurred in 1979. He was aquitted earlier this year of using a chemical spray in the same attack.

He was also fined $1,000 for renting the same apartment to two families, without either knowing about the other, and $250 for attacking the youth.

He was also fined $1,150 on three counts of driving with a suspended license.

"I didn't have to plead guilty, but I wanted to," Hsu said after the hearing yesterday. "To me, a couple of thousand doesn't make any difference, right?" Hsu called the hearing "very fair."

Hsu had requested earlier this year that the hearing be transferred from Prince George's County to the Calvert County Circuit Court, arguing that unfavorable media coverage prevented him from receiving a fair trial.

Prince George's prosecutors and housing officials who have long tried to jail Hsu for repeated housing code violations and other incidents stemming from his rental holdings expressed dismay that no jail sentence was imposed.

"Three grand? Is that all?" said Charles Deegan, county licensing and permits director.

"I'm bewildered," said John P. McKenna, an assistant state's attorney who prosecuted Hsu during his appeal. "Making him pay what is essentially a bill is not going to stop him."

Hsu was once cited by the District housing authorities as its most frequent housing code violator.

In the last couple of years there have been rumors that Hsu's real estate empire was beginning to fall apart. Hsu's lavish house in Potomac was auctioned by the state last year after he failed to pay more than $900,000 he owed in pending court judgments. The Guardian Federal Savings and Loan Association foreclosed the Emerson Apartments in Hyattsville after he failed to meet payments on two mortgages on the property.

But Hsu denies that he is no longer a very wealthy man. "I lose property and I buy property," he said. "It's an ongoing thing. Now I have bought more."