On 15 Jan 2007 17:37:57 -0800, "lsmartino"
wrote:


Rod Speed ha escrito:


They can do the estimate considering an ambient temperature of 20ºC -
25ºC. Check the datasheet of any semiconductor and learn something
before you write. Any rise in the temperature will shorten the lifespan
of the product. To me, that´s a quite profitable scenario.


Also, you will notice that the same circuit will have electrolytic
capacitors near heat sources, when it´s a well known fact that
heat shortens dramatically the life of electrolytics caps.

In practice that isnt a significant problem with domestic appliances.
Essentially because you dont see many electros in that situation with them.

Are you crazy? Have you ever seen a modern SMPS? Try to tell all us
that a SMPS (Switched Mode Power Supply, in case you don´t know what a
SMPS is) don´t HAVE electrolytics caps, and that those caps doesn´t
have a finite lifespan. Even electrolytics are classified based on
their MBTF at certain temperatures. Again, try to find the datasheet of
some electrolitycs caps, and educate yourself.

And just about anything electronic today is using SMPSs

The manufacturer know how to properly design an electronic
circuit in order to provide a long life, but it also it knows how
to design it to fail within a short term under certain conditions,

No they dont on that silly claim about surviving the
warranty fine, but failing immediately after that expires.

I replace enought ATX computer SMPSs before they hit 3 years - many
within 2, and too many within one. And they are running, in many
cases, on protected power supplies.


No one is telling that the product will explode right after the
warranty expires, but that it can be designed to fail within a short
life span, especially with cheap products.

and accordingly they estimate a warranty just long
enough to cover the product for a safe term, a
safe term for the manufacturer, not the user.

Have fun explaining how come not a single electronic device
I have ever owned has died just after the warranty has run out.

And that includes my latest gigantic widescreen TV too.

Of course it´s impossible to predict exactly how many years
the TV will last, but the manufacturer count with statistical
data which says, for instance, that a TV set is turned on
10 hours per day for instance, and taking that into account,
and estimating how long the weakest part of the TV will last
under these conditions, they can determine the warranty lapse.

Pity about the TVs that get left on all the time.


A TV, or a computer monitor left on all the time will last less time of
course. A CRT has a definite lifespan, and if the monitor or the TV set
is a LCD based one, the CFL bulbs used to light up the screen have a
definite lifespan. Did you knew that, Mr. Know Nothing ?

And certain parts ONLY fail on start-up because of power surges. Some
devices would run litterally forever if never shut off - others are
robust enough to handle starting and stopping but have finite life
devices. My experience with computer monitors (over 17 years) has been
those left on 24/7 generally outlast those that are started and
stopped several times a day. Phosphor burn used to be the major
problem with 24/7 operation. Today it is SMPS failure. I can't
remember the last monitor I had to replace due to CRT failure. My own
newest monitor is well over 5 years old now. It is generally never
turned off (just powers itself down when I leave)

The claim is completely fanciful and those making that sort of
claim have obviously never actually designed a damned thing.

And only the stupidest manufacturer would deliberatly design
their product to die as soon as the warranty has expired
anyway, because the bulk of those who had bought such
a dud wouldnt be buying another from that manufacturer.

How many people who owned Chevy Vegas bought a second one? THOUSANDS.
And how many who bought Vega bought another Chevy? Thousands and
thousands and tens of thousands. And the average Vega did NOT make it
through warranty. How many people who had their Cadillacs in the shop
more than in their driveway bought another Cadillac? Thousands. And a
few, after the second or third, got smart and bought a Lexus. It took
a friend 7 or 8 Caddies over 3 years to finally make the change. He
figured it had to just be his luck untill he talked to enough other
owners to be convinced it was the CAR, not him.


Tell that to the manufacturer of Coby products, for instance. They have
quite a long time selling trash that fails quite quickly.


They quote the useful lifetime of a hardrive in MTBF hours.

That is calculated, not measured. Convert that MTBF
to years and you will discover why they cant possibility
have tested them to get those numbers.

Don´t answer "it´s impossible" if you are not prepared to give
a real explanation. Samsung, Seagate, WD... any decent hard
drive manufactures gives an estimate lifetime of their products.
These estimates are provided in the datasheet of each harddrive.

And they are ESTIMATES, not measured results.

Educated guesses. Finite Element Analysis. Pretty accurate predictive
methodology.
Exactly, these are estimates,

Pity the claim was about TESTING, which doesnt happen, like I said.

and most of the time very accurate,

Like hell it is. Have you actually tried converting
the MTBF of a current hard drive to years ?


It can be something like 15 years or more of constant use, without a
stop. And I have seen hard drives surviving at least more than 10 years
of hard work.

specially those concerning the maximum number of startups/stops
the drive can tolerate before the heads get completely worn.

Wrong again. Its such a round number it cant have been produced
by TESTING, and the number of starts and stops dont produce
any wear of the heads with modern hard drives anyway.


You are wrong again. When the platters stops, the heads contact the
platters. While the platters are spinning at full speed, the heads are
separated from them by a small air cushion formed by the rotational
speed of the platter. As soon the HDD is turned off, the platters loses
speed, and eventually the air cushion dissapear, thus the heads make
contact with the platters. The same happens in reverse sequence when
the HDD starts. That´s why start / stop cicles have a definite impact
in any HDD. Have you ever wondered why a HDD last less in a home
environment than in a office environment?

Check this out http://phorums.com.au/archive/index.php/t-42666.html It
might teach you a thing or two.
ANd Hard drives that are never shut off generally DO last
significantly longer than those that get powered down (which is why I
disable power management on my servers). I have a set of 10 year old
scsi drives in one of the servers that will likely go another 10 years
if I don't scrap the server. That server has not had a SINGLE FAILURE
over those 10 years. It cost about $10,000 new. The drives were likely
over $1000 each. They are 8gb?
The EIDE drive I just installed is 160gb and cost $79.00. Will it last
10 years? Not likely!

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