Diagnosis of Malfunctions in Complex Electronic Assemblies. Final Report. Page: 34 of 66
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Maintenance and down-time problems are reduced by this tester simplifi-
cation, and they are more-easily localized to smaller sections of the build
line. The individual tester concept allows the tester design to be oriented
toward a type of error peculiar to the assembly being tested. The percent
of rejections caused by manufacturing errors compared to the percent of
rejects caused by component failures, the nature of the fabrication errors,
and the severity of stress that the error imparts to the circuitry are factors
that can determine which errors are most advantageous to isolate.
The feasibility of the concept could be more economically evaluated by a
small tester; however, in large-scale production operation, the large com-
puter or tape-controlled tester might be more economical.
Selection of a Typical Unit for Evaluation. The product piece selected for
evaluation is representative of a typical type of printed circuit board assem-
bly. The circuit board selected has 19 integrated circuits and 51 discrete
components. The individual circuit stages are logic circuits and are repre-
sentative of current trends in telemetry circuitry. The criteria
used to justify this typification were the ratio of discrete components to
integrated circuits, the total components per assembly, and the type of cir-
cuitry (Figure 3).
Definition of Concept. The feasibility of the following testing plan was evalu-
ated. The details of the plan are listed below.
" The testing plan was to use a group of small, economical, printed circuit
board testers integrated into the production line, which would evaluate
individual components or component network at the time of assembly.
" The evaluation would be done only on the more-complex assemblies.
" Testing would be done at two stages in fabrication: one test would be
performed after the discrete passive components, the other after the
active circuits had been assembled to the board.
" The tester would be a go/no-go type of tester, and would be simple
enough to enable the production assembler to operate it.
Plan for Checking Feasibility. The development plan was to choose a typical
printed circuit board with both integrated and discrete components and a
representative circuit type, and to develop a verification tester that would
evaluate the components and their installation by the production assembler
as an in-line process. The tester was to be evaluated as a diagnostic tester
also. The actual tester concept included two types of detectors; one to
evaluate discrete components prior to the installation of the active compo-
nents, and one to evaluate each stage functionally and check active components.
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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/m1/34/: accessed March 18, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.