Marginal checking-a technique to detect incipient failures

An investigation of the feasibility of detecting incipient electronic-system failures by measuring changes in critical parameters that can be correlated with subsequent failures is described. Subsystems under investigation include: (1) switching power supplies, (2) cables and connectors, (3) CMOS integrated circuits, and (4) voltage-controlled high-frequency oscillators. Techniques for incipient failure detection which have to date shown promise are: reverse leakage current/forward bias voltage monitoring and ultrasonic transmission signature analysis for power supply bridge rectifiers; center frequency drift and output power monitoring for voltage-controlled oscillators; and leakage current and supply current signature analysis for CMOS circuitry. In addition, techniques have been developed to detect cable chafing and cable insulation breakdown. The results of such investigations and the initial results of large-lot testing are presented