Forum: Reliability & Maintainability Questions and Answers
Posted by: Matt Wiltshire
Date posted: Tue Jul 27 9:33:51 US/Eastern 1999
Subject: Solar Load Testing
I'm looking for information on doing a sun loading test on low power laser devices. Do you have some test methodologies I can refer to?
Posted by:Andy Holton (firstname.lastname@example.org )
Date posted: Tue Jul 27 7:42:37 US/Eastern 1999
Subject: Connector Reliability
We are using high-quality connectors (e.g. Cannon, AMP) in a military application. All connectors are PCB mounted. Using MIL-HDBK-217F we predict relatively high failure rates, in fact over 50% of´a module's failure rate.
My questions: Does anybody have any information regarding the applicability of the MIL-HDBK predicted rates for PCB connectors? Does anybody have other sources of PCB-connector reliability? Does anybody have a justifiable scaling factor for the MIL-HDBK rates? Or, are the MIL-HDBK rates realistic for these connectors?
We need a quantitative rate for the connectors for use in the FMECA.
Thanks, Andy Holton
Posted by: Wu Xiangping (email@example.com )
Date posted: Mon Jul 26 22:20:15 US/Eastern 1999
Subject: Markov model
In Markov modeling,how to understand the hardware repair rate and software restore rate,and how to get these two parameters?
Posted by: Ananda Perera (Ananda.Perera@alliedsignal.com )
Organization:AlliedSignal Aerospace Canada
Date posted: Mon Jul 26 17:08:38 US/Eastern 1999
Subject: ESS Vibration Exposure
Environmental Stress Screening Guidelines for Assemblies 1990 published by the Institute of Environmental Sciences indicate that; (1)After subsequent repairs and/or modifications, repeat screen at -3dB level (70% RMS g) for 50% duration; (2) Total number of vibration exposures should not exceed five. ##### It is not clear whether these values were based on the Random Vibration Spectrum shown in Page 15 which gives a 6 gRMS Vibration Level. QUESTION: The above parameters, can it be used for any Vibration Level ? Is there any other method to determine the maximum vibration exposure that will not use excessive amount of useful life ?
Posted by: Hei-Ruey Jen (firstname.lastname@example.org )
Date posted: Mon Jul 26 15:47:41 US/Eastern 1999
Subject: microphonics interference
I have received a request to do reliability testing of microphonics' effect on microwave devices. From a website I found, someone claimed that there was no standard on how to test the microphonics sensitivity. Screwdriver tapping, simulated hail, etc. are few examples people have used. Does anyone know anything on how to perform this test correctly and reliably? This test is to simulate the rain drops and hail hitting an outdoor device, which will create sound to interfere microwave device performance. Thanks.