If the fuse blows as soon as you plug the oven in the wall, or when you open the door, the problem is likely with the door switches.
If the fuse blows as soon as you hit START, then it's likely that you have a shorted high-voltage capacitor.
If the fuse blows a few seconds after you hit START, then it's likely that you have an overheating / shorting high-voltage transformer.
If you or a friend decide to work on it, we have *critical* safety and disassembly info at our site, as well as other specific troubleshooting information and help.
In my professional opinion, people should not work on a microwave unless they are fully informed and aware of the deadly hazards and necessary precautions.
One can find such information and very specific in our safety and disassermbly text files at http://www.microwavedisplay.com
William Miller † MicrowaveDisplay.com, March 2007
