Abstract: A matrix of electrical termination points arranged in pairs is provided with a detection circuit for detecting short circuits between termination points. A transistor circuit is associated with each pair of termination points. A connection is provided from one of the points in each terminal pair to the transistor base which is forward biased in the absence of short circuits. A collector-emitter connection is provided through the transistor to the other terminal point in the terminal pair. A current indicator responsive to the collector-emitter current is provided for each transistor circuit. When the transistor base is forward biased, a collector-emitter current actuates thecurrent indicator associated therewith.