Fluke 9640A Series, Instruction Manual

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Maintenance
User-Initiated Self Test
7
7-23
Tests are performed in a sequence which, where possible, tests one aspect of
functionaility before testing dependent functions. As such, when multiple failures are
reported, the earlier failures are more likely to be indicative of the true source of a
problem.
Most tests operate by measuring a DC voltage at an indicated point. In many cases, the
test description will indicate that a specific frequency and/or amplitude of signal is being
routed through a particular section of circuitry which will result in the voltage being
measured. In some cases, the test being performed will also check to ensure specific
phase-locked loops are locked. Some other tests will not involve measuring a voltage, but
will instead be performing a more complex algorithmic check. For example, a memory
test.
Some of the tests, identified by a test name containing the letter M in the schematic
sequence number (e.g. S01.M01) are maths tests. These math tests compare results of two
or more other tests. Math tests allow properties that cannot be directly measured to be
tested. If the tests, on which the calculations are based, have failed, the associated maths
test(s) will also fail.
As part of the self-test operation, the unit will enter operating modes not directly
accessible as part of the normal functioning of the unit. Self-test failures at specific
frequencies and/or amplitudes should not be taken to imply the unit will operate correctly
outside these areas in normal use.
Some problems cannot be detected or diagnosed with self test alone and may require
additional manual testing with external equipment.