Abstract: A test fixture (10) which includes a base portion (12) and upstanding successive side walls (16, 17, and 18) integral with the base portion (12). Lateral grooves (22, 24, 26) extend around the inner surface of the three side walls (16, 17, and 18). A first movable clamp 30 is positioned between opposing side walls 16 and 18 and is movable in a selected slot (22, 24, 26) toward and away from the intermediate side wall 17. A second movable clamp (80) is mounted on and movable along the first clamp 30 and extends a small distance in the direction of the intermediate side wall (17). A circuit board (90) to be tested is typically clamped between the side walls (16 and 17) and the first and second clamps (30 and 80). A test probe (130) is positioned in a holder (91) which is mounted for movement between the first and third side walls (16 and 18) and toward and away from the second intermediate side wall (17). The position of the probe holder (91) relative to the board (90) is recognized by an optics system (142).

Abstract: A semiconductor test instrument (12) provides an AC interrogating signal to an element under test, such as a single pin of an IC. Horizontal and vertical signals are developed and applied to a display (33) which produces an analog signature signal representative of the operating condition of the test element. The horizontal and vertical signals are converted to digital signals by an A-D converter (34) and stored in memory (39). An analog signature is also obtained from the same element as the test element but which is known to be good. The horizontal and vertical components of this signature are also converted into digital signals and stored in memory (42). The test and reference digital signals are then compared and those test digital signals which are different identified. The analog signatures corresponding to both the test and reference digital values are then reconstructed for display and superimposed, for viewing by an operator.