Abstract: A device in cludes two mechanisms mounted beside the two longitudinal sides of an adapter supporting the customary feelers of a test apparatus. Each mechanism is adustable transversely on the adapter, and includes a number of pulleys having coplanar parallel axes and engaging a respective edge of the printed circuit plate of an electronic module for testing. The mechanisms are activated by a common actuator against the action of springs so as to bring the plate into contact with the feelers. The pulleys of each mechanism are rotated simultaneously by a belt activated by a toothed drive roller so sized as to mesh with the respective mechanism regardless of the position of the same.