Abstract: Selected test points of conductors on the substrate of a printed circuit board are tested by positioning the circuit board adjacent an array of electrodes or by utilizing a set of conductors in or on the substrate as an array of electrodes. An electric potential is set up by applying an inhomogeneous electric field to the array of electrodes or to the conductors to be tested, and signals denoting the characteristics of the electric potential are generated. Such signals are evaluated by a suitable circuit, for example, by comparing them with reference signals which are indicative of passable or non-defective conductors, i.e., of conductors which are devoid of open and/or short circuits, or by comparing the generated signals with each other. Test probes are utilized to apply an electric field to the conductors to be tested and/or to transmit signals to the evaluating circuit.