REG NASA-LLIS-0398-1995 Lessons Learned - Galileo Command and Data Subsystem (CDS) Marginal Power Supply Voltages.pdf

1、Lessons Learned Entry: 0398Lesson Info:a71 Lesson Number: 0398a71 Lesson Date: 1995-06-07a71 Submitting Organization: JPLa71 Submitted by: J.K. LangmaierSubject: Galileo Command and Data Subsystem (CDS) Marginal Power Supply Voltages Abstract: After rework of a Galileo subsystem, it was discovered t

2、hat the size of PWB traces in a subsystem power supply had the effect of limiting voltages elsewhere in the system. The problem was corrected by adding conductors in parallel with the traces.Subsystem design analysis must consider all aspects of the end-to-end implementation, and subsystem testing m

3、ust duplicate all aspects of the flight system configuration that could affect subsystem performance. Description of Driving Event: Following rework of the Galileo Spin Bearing Assembly (SBA), tests were conducted at the system level to assure that the changes made in the SBA did not affect spacecra

4、ft operation. Results of the tests showed lower than expected CDS voltages on the despun side of the CDS. These low voltages were isolated to the trace size of the printed wiring board conductors within the main CDS power supply. The problem was corrected by adding conductors in parallel with the po

5、wer supply printed wiring board traces.Reference(s): PFR #44928Lesson(s) Learned: The trace size of subsystem printed wiring board conductors can affect system level voltages.Recommendation(s): Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1. Subsy

6、stem design analysis must not only include the circuit design, but all aspects of the end-to-end implementation, including such things as current carrying capacity of printed wiring board conductors.2. Testing at the subsystem level must include realistic duplication of the flight system configurati

7、on that could affect subsystem performance, including consideration for worst case system conditions.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Parts Materials & Processesa71 Test & VerificationAdditional Info: Approval Info: a71 Approval Date: 1987-11-17a71 Approval Name: Carol Dumaina71 Approval Organization: 125-204a71 Approval Phone Number: 818-354-8242Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-