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FEC200 Dual Diodes; Testing with Two Stations


DEFINITION: For purposes of this paper, dual diodes are three terminal devices with either a common Anode or a common Cathode terminal.

A pair of multiplex stations on the FEC200, either 1, 2 or 3, 4 can be used to test the two diodes in the device. A single test program can be written that treats the two diodes as a single product. A pseudo-test called SWITCH switches the tester back and forth between stations 1 and 2 or between 3 and 4. Although the test connections change, the program behaves as though still running in the station where the test program resides and where the "Start Test" signal originates.


Any FEC200 running recent MAXX software can perform this feature. However un-modified testers cannot tell if the two diodes are shorted together or whether a three-terminal part with just one diode has been substituted. The solution for this is a fairly easy modification to the FEC200 multiplexer relays. When testing station 1, a 100hm resistor is connected across station 2. (Same with 3 and 4) If the part is shorted from diode to diode or contains just one diode, then the 100Ohm resistor in parallel will cause the part to fail.


FEC200 testers shipped after this date will have the 100? resistors installed. If you want to use this feature on older testers, please contact the factory for an inexpensive modification.


Although it would appear that the two multiplex stations could have a common connection at the back of the tester, this is not a good idea. For best accuracy, especially with THERMAL RESPONSE tests, you should run all of the test cables from the two multiplexers out to the manual test station or device handler.


If you would like us to provide a manual test station that is setup for testing dual diodes, please let us know.

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Last Updated September 12, 2007
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