Simply touch LeakSeeker's gold-plated probe on any solder pad along the suspicious trace and LeakSeeker automatically calibrates itself to the resistance of the defect, within a 24 milliohm "window". Because the test voltage is a current-limited eight volts, it will power through good diodes to activate shorted components beyond. Touch a pad in one direction or the other and LeakSeeker beeps higher or lower and lights the LED distance scale to indicate that you're getting closer or further from the defect. The 24 milliohm window allows about 2 to 3 inches of pcb trace to be checked, then automatically re-calibrates itself to a new window as you get closer to the short