The Polar Toneohm 550 is ideally suited for electronic manufacturing and service industries as a short circuit and fault-finding aid. The highly sensitive variable-frequency audio tone output makes it ideal for locating the physical location of short circuits on PC boards and within system wiring. In many cases, shorts may be located to within 0.2 inches of the actual fault location, without the need to disconnect associated components of wiring. Frequency resolution of the audio tone is accurately dependent on the resistance between two hand-held Kelvin probes. If the probes are placed on two tracks of a PC board and a tone is heard, the tone indicates there is a short circuit between the two tracks. By moving one of the probes along its track until the tone reaches its highest pitch, the precise location of a short can be found.