A system for checking boards bearing integrated circuits, wherein a program card is read automatically to provide both test input signals to the board and simulation output signals representative of the correct output signals which should be delivered by the board in response to the test input signals, and wherein the actual output signals delivered by the board are compared with the simulation output signals for generating indicia representing any defects which may exist in the board.
A test circuit for stimulating the inputs of preprogrammed logic circuits, having a pulse input terminal connected to one of the inputs of a NAND circuit. The output of the NAND circuit is connected via a first resistor to the base of a first switching PNP transistor, the emitter of which is connected to a first positive voltage supply terminal and the collector of which is connected to the collector of a second switching NPN transistor. The base of the second NPN transistor is connected both through a fourth resistor to an earth terminal of the circuit system and through a third resistor and a second resistor to a second positive voltage supply terminal and the emitter of which is connected both through a fifth resistor to the earth terminal of the circuit system and to an output terminal. The output terminal is connected to a measuring point or probe which is connected to the input of the connected-up logic circuit. The connected-up logic circuit is connected to the earth terminal of the test circuit system.
A plurality of voltage comparators are each connected to a corresponding pin of an integrated circuit on a wiring board. Each of the comparators is also connected to a sequencer which sequentially provides reference voltages to the comparators to check for shorts to ground, shorts to high voltage and incorrect signal levels at each of the pins of the integrated circuit. This apparatus may be used to test wiring boards having a wide variety of types of integrated circuits mounted thereon.
An electronic circuitry servicing system having an operations manual setting forth servicing procedures such as function checking, troubleshooting, and calibration, a template fitting on the circuit being serviced and providing probe access to test points of the surface and graphic information about the circuit and a test fixture for coordinating test signals and measurements.
A self-contained test apparatus is provided for performing functional tests n any one of a plurality of varied function, modular circuit cards. The apparatus includes a power source and a series of switches electrically connecting the power source to the inputs of a modular circuit card under test. Each of the switches is manually set to a predetermined position based upon the function of the modular circuit card. One of either a TTL logical high or low is applied to each of the inputs. The test apparatus includes means for simulating the normal operational load characteristics of the modular circuit card in order to effectively test the card's function. Means are further provided for comparing a TTL logic response generated at each of the outputs with an expected response. The comparison is indicative of a pass/fail condition at each output whereby the functional test is passed only if all outputs achieve a pass condition.
