Diagnosis of Malfunctions in Complex Electronic Assemblies. Final Report. Page: 49 of 66
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" The tester shall be designed to adapt to open setup diagnostic equipment
such as scopes, counters, and voltmeters.
The additional circuit reactances that would result from bringing out the
many circuit nodes to the front panel and the additional circuitry necessary
to switch the loads individually to various values and to furnish the additional
loading, excitation, and fixture connections for three levels of assembly
were recognized as critical parameters. Development work included defi-
nitions of wire dress and fabrication techniques and evaluation of the
feasibility of such an approach.
Development circuitry simulation in the switching circuits showed the parame-
ters to be very critical. Cross-talk between conductors and additional wire
length caused severe differences in unit waveform parameters and, in some
cases, the unit developed spurious oscillating conditions in various nodes.
'This ettect was minimized to an acceptabLe level by strategic choice of wire
routing and by shielding critical circuits. Point-to-point wiring was required
with no bundling of critical circuit wires.
Results. As a result of the study, a production tester was built according
to the guide lines of the developed design criteria.
The tester extended the troubleshooting capabilities of production lines, and
the initial cost was 10 to 1 thousand dollars less than the cost of an in-
spection tester. The capability o evaluating the individual circuit board
increased the accuracy of diagnosis in the oscillator circuit and allowed
electrical verification of these circuit boards after rework and prior to
reassembly. The probability of accidental short circuits caused by probing
was also reduced by bringing testpoints on the printed circuit board out
to the panel.
This tester concept proved to be a feasible and economical method of ex-
tending the capacity and range of diagnostic test equipment when the inspection
testing and troubleshooting overload inspection equipment was overloaded
and when particularly difficult diagnostic problems occurred. Figures 8 and
9 show photographs of this tester.
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Losure, J. A. Diagnosis of Malfunctions in Complex Electronic Assemblies. Final Report., report, January 1, 1971; Kansas City, Missouri. (https://digital.library.unt.edu/ark:/67531/metadc1031893/m1/49/: accessed March 24, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.