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CERES +15V Power Converter Anomaly



Leonard Kopia

November 3, 1998

EFFORT ON CONVERTER ANOMALY DETERMINATION CONTINUES --

  • The investigation into the cause of the +15 volt converter anomaly on the Clouds and the Earth's Radiant Energy System (CERES) Proto-Flight Model (PFM) continues. The overvoltage tests at TRW on the downstream circuit components have been underway for several weeks. To date, no detrimental effects on the components have been observed in this elevated voltage condition. A set of tests is also underway on the converters using external leads which have been connected to specific circuit attachment points. A limited series of tests under varying temperature conditions has been conducted to try and simulate hypothesized failure conditions on the converter but has not duplicated the anomaly as yet. Because components in the converter package are so highly integrated, lead attachment requires great care since there exists a distinct possibility of damaging adjacent connections and components. This fact limits the nature of the tests which can be conducted. Since a definitive cause of the anomaly has not yet been determined, it has been assumed that a latent failure mode exists on all converters, and a plan is in place to replace converters on all instruments. The replacements, which are from a more recent lot date code, contain a manufacturers process change which eliminates one of the more highly suspected, but as yet unverified, causes of the anomaly. A back-up plan is in place should there be delivery problems with the replacement parts for Flight Models 1 and 2. Additional units are on order and will be available at a later date for Flight Models 3 though 5.

  • Plans are in process to turn the PFM instrument on again in mid-November to gain additional information on degradation rates from which a better basis of lifetime prediction may be formed.


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