The company said it is instituting mandatory one-week vacations for 400 to 600 of its 1,700 employees. The money-saving measures are the second round of cutbacks since former Hewlett-Packard executive Paul Ely took over as president of Convergent Technologies four months ago. The company is also cutting its total time off for workers from four weeks to three and has asked salaried professionals to work extended hours. Convergent said Friday that the mandatory vacations will affect manufacturing workers in the company’s CT division, which produces work stations and super-minicomputers. The division has suffered a slowdown in orders.