Browse Prior Art Database

Shorts Tester

IP.com Disclosure Number: IPCOM000040440D
Original Publication Date: 1987-Nov-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Ambrico, LE: AUTHOR [+2]

Abstract

Apparatus or tester 10 is designed to manually or automatically test a card 11 for shorts prior to burn-in. The test thus protects cards from becoming damaged due to shorts during burn-in. Further, the apparatus protects cards from becoming damaged during test due to excessive voltage. In manual mode, an ohmmeter 12 is connected to a ganged rotary switch 13 so that by operator rotation of the switch, various test points of card 11 are connected to ohmmeter 12, which can be observed by the operator for shorted conditions. To test a card in automatic mode, an operator first plugs the card into a test fixture and presses the "start" button 15. The test for shorts is then performed under microprocessor control. Each test point is checked against all remaining test points for shorts.

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Shorts Tester

Apparatus or tester 10 is designed to manually or automatically test a card 11 for shorts prior to burn-in. The test thus protects cards from becoming damaged due to shorts during burn-in. Further, the apparatus protects cards from becoming damaged during test due to excessive voltage. In manual mode, an ohmmeter 12 is connected to a ganged rotary switch 13 so that by operator rotation of the switch, various test points of card 11 are connected to ohmmeter 12, which can be observed by the operator for shorted conditions. To test a card in automatic mode, an operator first plugs the card into a test fixture and presses the "start" button 15. The test for shorts is then performed under microprocessor control. Each test point is checked against all remaining test points for shorts. A pass is indicated by a green LED (light-emitting diode; a fail is indicated by red LEDs showing which test points were shorted. Automatic operation of the tester will now be described. Upon pressing the "start" button 15, relays 4 and 7 close. Current is forced into the +5 test point on card 11 and out of the -1.5 test point to ground.

Depending on the impedance between these two test points, a voltage will be developed between the two test points with respect to ground.

This voltage appears at the inverting input of comparator op amp 16 (pin 2) and is compared to a reference voltage at the non- inverting input (pin 3). The result of this comparison is stored in buffered m...