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From: Martin Brown <'''newspam'''@nonad.co.uk>
Newsgroups: sci.electronics.design
Subject: Re: Predictive failures
Date: Tue, 16 Apr 2024 09:45:34 +0100
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On 15/04/2024 18:13, Don Y wrote:
> Is there a general rule of thumb for signalling the likelihood of
> an "imminent" (for some value of "imminent") hardware failure?

You have to be very careful that the additional complexity doesn't 
itself introduce new annoying failure modes. My previous car had 
filament bulb failure sensors (new one is LED) of which the one for the 
parking light had itself failed - the parking light still worked. 
However, the car would great me with "parking light failure" every time 
I started the engine and the main dealer refused to cancel it.

Repair of parking light sensor failure required swapping out the 
*entire* front light assembly since it was built in one time hot glue. 
That would be a very expensive "repair" for a trivial fault.

The parking light is not even a required feature.

> I suspect most would involve *relative* changes that would be
> suggestive of changing conditions in the components (and not
> directly related to environmental influences).
> 
> So, perhaps, a good strategy is to just "watch" everything and
> notice the sorts of changes you "typically" encounter in the hope
> that something of greater magnitude would be a harbinger...

Monitoring temperature, voltage supply and current consumption isn't a 
bad idea. If they get unexpectedly out of line something is wrong. 
Likewise with power on self tests you can catch some latent failures 
before they actually affect normal operation.

-- 
Martin Brown