[mythtv-users] HDHR in harsh enviroments

Brian Wood beww at beww.org
Sat Dec 27 01:59:23 UTC 2008


On Friday 26 December 2008 18:35:12 BP wrote:
> James Van Vleet wrote:
> > On Thursday 25 December 2008 11:48:14 Daniel Kristjansson wrote:
> >
> >
> >
> > Has anyone done this?   I was wondering if an HDHR could stand up to the
> > kind of temperature swings that can happen in an attic.  I was
> > contemplating something like this in the spring.  A few of us have
> > posted to the HDHR forum and finally were told only that it was
> > guaranteed to work in 0-40C (32-104F).
>
> I've had mine in the attic for two years without a problem.  It gets up
> to 110-120F in the summer and rarely below freezing in the winter.  I
> did have a router go bad, but the replacement and my switch have
> survived in the same location.

Elevated temps will reduce the MTBF. If the unit was going to fail after 2 
years, it might fail at 18 months. If it was going to fail in 13 years, it 
might then fail at 12 years. So the difference might not matter to you at 
all.

(those numbers are just random from the hat, not specific predictions)

Other factors are important (maybe more so). Glitches on the power line, 
lightning hits nearby, cosmic ray hits, stray neutrons from your 
neighbor's "special" project (Just kidding Mr. Gov't Man) and other 
unpredictable things.

The answer is don't put electronics in high temp locations unless you have to. 
If you have to, then do it, recognizing the cost. The attic location will, 
however, protect the unit from other common hazards like pets, children, 
coffee spills, being "housecleaned" and other problems, so it might actually 
last longer.

Obviously the unit is not going to work perfectly at 104F and then immediately 
fail if the temp goes up a degree. The maker is basing those numbers on the 
specs of the components used, which should be expressed as a series of 
curves, but they are not going to go into that with a typical customer.

-- 
beww
beww at beww.org


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