Diagnosis of Malfunctions in Complex Electronic Assemblies. Final Report. Page: 52 of 66
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Development of Tester Concept Number 3
Defining the Areas of Need. The third tester concept deals with the feasibility
of extending the diagnostic capability of the inspection tester by a supple-
mentary type of diagnostic tester. A review of the testers being used on a
telemetry program currently in production proved a need for this type of
extension in the following areas.
" There were several levels of assembly that had no electrical inspection
requirements; consequently, no tester was available to evaluate units at
those assembly levels. Therefore, extension of tester capabilities was
necessary to load and excite these units and test them at intermediate
assembly levels. Testing at intermediate assembly levels permits manu-
facturing errors, intermittent failures, and defective components to be
detected before they are made less accessible by higher levels of assembly,
thereby reducing rework. It also minimizes loss of intermittent failures
that might be undetected at higher levels of assembly because of changes
in operating environment or tester limitations. When test points are inac-
cessible, it is desirable to disassemble only to the point where access is
possible. Intermediate level testing aids that purpose.
" Tester diagnostic capabilities were not always adequate to accomplish
diagnosis at the failure level.
Troubleshooting at Intermediate Assembly Levels. The extension of tester
equipment capabilities to test the intermediate level of assembly, where
no electrical tester was available for testing or troubleshooting, involved
three principle areas: additional loads, B-supply voltages, and, sometimes,
cxcitation or signal stimuli. Any assembly level higher than the power
supply level needs only to have the input dc voltage that simulates the bat-
teries as its input power source.
Analysis revealed that the master circuitry that triggers a large part of the
logic circuitry would furnish most of the excitation necessary for testing
at the intermediate levels of this particular product.
The development concept definition was to design and build a generator
that would furnish parallel output pulses to excite the logic assembly. The
generator was to be portable so it could be used on any of the applicable,
higher-level testers, to have open setup loads that would simulate the vari-
ous subassembly loads, and to furnish dummy RF loads for the transmitter
to allow the transmitter to be operated on the lower-level testers that had
no terminating transmitter port connection.
The tester concepts and the preliminary design were developed and recom-
mended for production application and, as a result, Production built a
generator of special design to he used as auxiliary equipment to extend the
excitation capabilities of the inspection testers. That generator is shown
in Figure 10.
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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/m1/52/: accessed March 26, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.