Device and method for detecting short-circuit fault point of finished printed circuit board

The invention provides a finished printed circuit board short circuit fault point tracking device, which comprises an excitation signal generator, an excitation signal shunt circuit, four output ends, a probe and a short circuit signal processor, wherein the excitation signal generator sends out two paths of time-sharing independent output DC pulsating excitation signals, the two paths of excitation signals are divided into four paths of electric signals through an excitation signal dividing circuit, the four paths of electric signals are inputted into a circuit board to be tested through four output ends, one end of the probe makes relative contact with the circuit board to be tested to move, and collected short-circuit signals are transmitted to a short-circuit signal processor; and the short-circuit signal processor converts the short-circuit signal into an optical signal for indicating the position of a short-circuit fault point. The device can accurately search welding short-circuit points of tiny device