Tim Wilson was a star trumpeter. But he began to go blind. Now – instead of playing Puccini’s “La Bohème” at San Francisco’s War Memorial Opera House, the 58-year-old maestro is working up to 14 hours a day coaxing “Jingle Bells” out of beginners and pouring much of his life savings into bringing music back to a school where 95 percent of students live in poverty. If he can take kids who can’t play a note and teach them a song, Wilson believes, they will not just feel successful, but see new possibilities everywhere in their lives.