Baltimore County police thought they had ended a spate of car thefts in the townhouse communities along Belair Road last week when they caught a 19-year-old Parkville man in the act of ripping a telephone out of a parked truck.

But Kenneth Schiminger, 26, who lives in the Belmont townhouse development off Belair Road above Putty Hill, said he knows better.

He awoke yesterday morning, he said, to find a $500 Kenwood stereo speaker and an $800 amplifier missing from his 1988 Ford Escort. A side window also was broken. He said it's the fifth time his car has been broken into during the past year. The thieves first jimmied open his next-door neighbor's car, he said, stole some softball equipment and used a bat to smash his car window to get at the stereo gear.

Officer Frank Becker of the Parkville station said he has charged Russell Miller, of the 8700 block Kingsridge Road in Parkville, with breaking into three cars last week. He said Miller is a suspect in 14 car thefts -- all of which took place April 15 and 16 in the Belmont development and farther south of Putty Hill Road. Mr. Miller was arrested on Green Needle Drive, the officer said.

"It's usually kids from the area," he said of the repeated thefts. "We'll catch one group of kids, and then another starts."

Officer James Lynch, also of Parkville, said the department recorded 14 thefts from autos in the precinct in 1991, 46 thefts of auto accessories, such as stereo systems, and 46 thefts of vehicles.

Mr. Schiminger said he has lived in Belmont since he was a small child and recently bought a house from his parents. He said crime there has gotten worse over the years. "It's getting ridiculous, . . ." he said, noting that in previous thefts he has lost $40 in change, and neighbors have lost wheel covers and, occasionally, their cars.

Officer Becker said the man he arrested had $17 in quarters in his pockets, and coin holders missing from other cars broken into that night.