Why Is TMV Needed for Automated Test Fixture?

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    Y Not

    TMV newbie post from a test engineer. This whole TMV world kind of fascinates and frustrates me at the same time. The company I work for has an automated test fixture that tests the I/O signals of a fully functioning microcomputer board. The test fixture consists of a tester board which cables directly to the board being tested. On both boards, each I/O signal is controlled directly by the respective microcomputer’s firmware.
    There is a software test program that instructs the microcomputers to set I/O signals high and low on one board and detect the level of the corresponding I/O signals on the other board. In addition, there is a validation extension to the test program which injects I/O signal faults by instructing the microcomputer firmware to inhibit each signal, one at a time, from being set high or low. This shows that the test program detects stuck I/O signals.
    I don’t see how there can be much variation in such an automated measurement system, so can the Gage R&R be done away with? If not, how about a small sample size? I read about doing 20 samples, 30% of which have a single fault, done 3 different times, by 2 different operators. But in my case, each sample will have over 60 faults injected.



    @YNot – Ideally what you would want to do is construct samples that have known and distinct defects – in this case reduced signal output at specific levels. You still want to have the operators in the system as they may hook up the boards differently, with different connection seating for example. Your MSA isn’t specifically looking at the correct I/O signal, but whether degradations of the signals are correctly interpreted by the test apparatus.



    Thank you for the response.


    Mike Carnell

    @Ynot I would just skip the MSA if you don’t see where there can be much variation. There is probably a Supplier Engineer that knows all those parts were tested before that got to you so he probably doesn’t see much point in your test either so why not just skip your test to. Just eliminate anything that you can’t figure out.

    What does your field failure data say? Zero escapes?

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