Archived from groups: comp.sys.laptops (
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> A laptop component can fail ANY time. I have had bad motherboards,
But statistically, they usually don't fail "ANY" time. Let me give you
a quick lesson in electronic product warranties (and pardon me for
sounding condescending, but you're speaking the irritating foolishness
of a gambler who claims he's on a "winning streak", so it's
justified): The failure rate for electronic appliances follows a curve
that looks something like an inverse bell. There is a high rate of
failure in the initial [days/months] due to infant mortality issues.
The failure rate then drops to a low noise level for some period of
time, and then begins to climb again as components begin to physically
wear out.
The manufacturer's task is twofold:
a) to perform enough in-house testing (burn in) that a significant
proportion of infant mortality cases don't get out of the factory,
because it's much cheaper to fix a dead baby in the factory than have
a user ship it back after going through distribution.
b) to calculate how much warranty to offer on the product as a whole
so that the warranty expires before too many units have reached the
"wear-out" stage of their life. This calculation is based, in part, on
estimated "typical usage" scenarios. For instance, one of the biggest
stresses on a system is power-up, partly due to large current inrush
charging all those bypass caps on the board, and partly due to thermal
cycling effects which flex all the joints on the board, and I'm
particularly thinking here of the joints under BGA devices. The
manufacturer assumes a certain usage pattern when calculating MTBF. If
you happen to use your computer atypically, you might become an early
failure and /that/ will make you a frequent warranty-claimant.
Engineering realities mean that, barring design flaws or unusual
circumstances, the parts of a portable computer that start climbing
that lifespan-related right-hand edge of the failure curve first are
the hard drive, optical drive and LCD backlight. As a rule, the
manufacturer does not offer separate warranties on these components
(exceptions exist: for example, a product I was responsible for
designing offered a 5-year parts & labor warranty on the appliance as
a whole, but only a 1-year warranty on the LCD backlight - after the
first year, you have to pay parts costs for replacing the CCFL. This
product was designed to run 24/7 and the CCFL was rated for 10,000
hours, which is only slightly more than a year).
Yes, if you play the slots in Vegas, occasionally you will walk away
with a $10,000 jackpot, but the odds are very good that you'll walk
away at the end of a day's gambling with slightly less money than you
started out with.
Extended warranties are a profit center for the company that offers
them, much like (say) health insurance. The prices are calculated
statistically with a certain anticipated profit level. They are not an
altruistic service offered for the good of the impoverished working
man.
Buy all the lottery tickets you like - we need compulsive gamblers to
fund our school system - but at least understand that it's a
compulsion, and not scientifically justifiable.
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