cant get oven on hob ok, clock fault?

Hello, cant ge oven to come on clock clicks off when turn therm dial and oven dial..have striped oven no loose wires thinking prob with circuit board........has diode blown...can I get another circuit board to replace and is it the answer.....thinking expensive problem.....not had oven working since before xmas.....any advice as smeg dont want to know.....many thanks Helen