Test the PiSmart fuse tutorial
From Wiki
1. Turn the multimeter to the position shown below. Bold text 2. Use the red and black test leads of the multimeter to test the on/off of the components in the figure below. The red and black test leads are respectively in contact with the two ends of the component (the component has "P" written on it). When the multimeter has a sound, it indicates that PiSmart's fuse is good, if not, it indicates that PiSmart's fuse is bad. END