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4 Bit Adder Circuit ( Fault 1)
The GIF animation below shows how a good 4 Bit Adder Assembly works. Circuit is TTL. Schematic and Test Setup are shown below. Observe the fault and using the schematic below diagnose the must probable local
GIF Preview( If you want to stop the action and analyse circuit you must download .AVI version)
Download Adder with Fault 1(AVI). AOL 4.0 and IE 4.0 Only
Answer: U1-Pin 1 is floating. You cannot distinguish between an internal or external discontinuity. We do observe that U2 is working correctly; therefore, continuity to it is O.K. In the real rather than virtual world a technician need only measure continuity with an ohmmeter from U1-Pin 1 to U2-Pin 2. If connection measures more than fraction of an ohm the technician would repair connection. If continuity is good, than the technician would replace U1. Thus, this circuit could be troubleshot without having to gain access to assembly with power applied.