Abstract: A testing method and machine for automatic adjustment of the conveying means for printed circuit boards (20) in a test machine of modular type, comprising a test module (1), a loading module (2), and an unloading module (3), wherein respective moveable rails (110, 111; 210, 211; 310, 311)are provided to support the rails (110, 111) are moved toward each other, with an independent movement, and temporarily stopped on detection of corresponding stops (26) indicative of the width of the printed circuit board (20) to be tested, then withdrawn by a fixed, pre-established distance, so as to be disposed in the correct conveying position, the rails (210, 211; 310, 311) of the other modules (2, 3) being brought toward each other and stopped on detection of fixed stops in the test module (1), so as to be disposed in perfect alignment with the rails (110, 111).

Abstract: A method and a device for automatic adjustment of the conveying means for printed circuits (20) in a test machine of modular type, comprising a test module (1), a loading module (2), and an unloading module (3), wherein respective moveable rails (110, 111; 210, 2111; 310, 311) are provided to support said means for conveying the printed circuit (20), advantageously in the form of belts (10, 119), wherein said rails (110, 111) are moved toward each other, with an independent movement, and temporarily stopped on detection of corresponding stops (26) indicative of the width of the printed circuit (20) to be tested, then withdrawn by a fixed, pre-established distance, so as to be disposed in the correct conveying position, the rails (210, 211; 310, 311) of the other modules (2, 3) being brought toward each other and stopped on detection of fixed stops in the test module (1), so as to be disposed in perfect alignment with said rails (110, 111).

Abstract: An automatic adjustment method is described for elimination of the centering error during the electrical test on printed circuit boards, in particular SMT (surface mounting technology) printed circuit boards, in which metal surface bump contacts or pads are used for connection of the components to the PCB. The method includes the step of associating each pad of a centering profile by a function .rho.=f(.theta.). An electrical test is performed which classifies the pads as open and okay. The .rho..sub.max and .rho..sub.min curves are determined corresponding to a lower envelope of the centering profiles of the pads found to have no errors of open circuit and an upper envelope of the centering profiles of the pads found to have an error of open circuit, respectively. A zone A is determined of possible displacements to the test needles with respect to the nominal points of contact between needles and pads. An optimal correction .rho..sub.opt and .theta..sub.opt is determined.

Abstract: A method for correcting misalignment between test needles and test points during multiple electrical tests on printed circuit boards, in which setting up the machine to carry out the test on a circuit board or group of circuit boards, and hence correction of any misalignment, takes place without removing the circuit boards from the test area.

Abstract: An interface device for converting the test point grids of machines for electrically testing unassembled printed circuit boards to a lower density grid, to be interposed between the test machine grid (1) and the corresponding fixture (3). The interface device comprises a plurality of flat parallel plates (10, 11, 12, 13, 14) suitably perforated so that needles can pass through them, the plate (14) facing the grid (1) having the same perforation as the grid (1) and having some of its holes (21) unoccupied by said needles (15), whilst the outer plates (10, 11) have all the holes occupied by said needles (15), reproducing the desired lower density grid configuration.

Abstract: A system for marking printed circuit boards (4), that can be applied to machines (1) for electrically testing printed circuit boards, in which the circuit to be tested is positioned in the test area of the machine, where a constant-pitch grid, or pin bed is provided, with an adapter (6) interposed between said pin bed and the printed circuit board (4), the marking system comprising at least one marking element (20) located in the adapter (6) and including a pad (21) that is moved linearly by means of an electric actuator (27, 26, 25), on a command given by the testing machine itself, through a pair of points in the pin bed.