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[filmscanners] RE: HD failure [was RE: keeping the 16bit scans}

> From: Kapetanakis, Constantine
> I am not sure where people get the impression that by not switching
> equipment "off" they will extend its life. For 99.9% of the time that is
> false.
> Equipment fails from either "random stresses","manufacturing defects" and
> "wear-out". When any equipment is turned off is NOT subjected to any
> external stresses, wear-out is pushed further out etc.
> As a reliability engineer i have not run across a case where leaving
> equipment "ON" improved its life.

You're missing one common failure mechanism: thermal stress. When an
electronic circuit that consumes significant power is turned on, it warms
up, and things like transistor and IC bond wires and solder joints flex
slightly. When it's turned off, it cools off, and everything flexes back.
This can eventually lead to mechanical failures, which is exactly why the
burn-in of electronic devices before they leave the factory involves
repeated power cycling, rather than just leaving it on throughout the
burn-in period. Whether this effect or wear-out dominates depends upon the
particulars, but this is a well-known effect.


Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@ix.netcom.com

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