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Digital Troubleshooting
Prerequisite : A knowledge of binary addition, logic gates, and schematic reading.

Observe the LED's on the test fixture below and note failure that occurred during testing and also note the additions that were completed correctly. You are to use this information to troubleshoot the Adder Assembly using a virtual logic probe. The adder schematic and test setup are shown below. The logic probe recordings (Probe U1 through Probe U2)  were made when the system was in the failure state shown as the Error Capture Frame below.

Adder- Four Bit Test Fixture

AdderPNL.gif (19569 bytes)

 

Error Capture Frame

ADDsmpnl.gif (4512 bytes)

Select to probe one of  IC's below(U1 - U5) as required to determine cause of fault shown in " Error Capture Frame."

Probe U1    Probe U2     Probe U3    Probe U4    Probe U5

 

Adder Schematic

addersch.gif (15949 bytes)

            Adder Test Setup

addsetup.gif (5586 bytes)