An adapter is disclosed for a detector including a plurality of detector modules. A method is further disclosed for carrying out faultfinding on the detector including such an adapter. It is possible for an electrical cross-connection to be produced between at least one first detector module and a second slot on a printed circuit board, and between a second detector module and a first slot of the printed circuit board by use of the adapter. The adapter makes possible simple and rapid faultfinding of a defective component of the detector by way of a first and a second measurement, in which measurements a position of the faulty output signal is determined.