Even a dual voltage machine will usually have a switch that you have to flip to change it over. Changing the cord only makes it possible to plug something in, but it doesn't prevent the machine from burning out if used at the wrong voltage. Not all Bernina sewing machines are dual voltage. Check with Bernina for your specific machine. I burned out a hair dryer using it without a transformer and almost scared myself silly at the same time, so be very careful with your sewing machine.