Forty musicians at the Rochester Philharmonic Orchestra in New York turned in their instruments for picket signs Tuesday after voting unanimously to reject a temporary contract. A spokesman for the musicians described the action as a protest, not a strike. The rejected proposal guaranteed musicians their current $600 weekly salaries, but only if Monroe County agreed to up its yearly contribution to the symphony by $170,000. If not, salaries would drop to $570 a week. The musicians were laid off Sept. 13, when their contract expired and they rejected a management offer for a one-year contract that cut salaries by $19-a-week and cut nine weeks from the season.