On Sat, 10 Sep 2016 19:17:46 -0700, T wrote:

On 09/10/2016 12:41 PM, Ed Pawlowski wrote:
tolerance for MTBF

Hi Ed,

That is not what MBTF means. If the bulb had, say 1000 hour
MBTF, it would mean that you put 1000 bulbs in a test bench
and ran them for an hour. Only one failed. MBTF does not
tell you anything about the second and so forth hours.
(I did MBTF analysis for the military.)

A good gauge of how long something will last is the warranty.
They taught us in college to set it at 90% of useful lifespan.
Course, some manufacturers are just lazy and set it at a year.

-T
And others figure (correctly in most cases) a customer will not spend
$8 to send the defective unit back to china to get a $2 part replaced
under warranty.

It was bad enough when a "lifetime warranteed" memory module for my
laptop failed and one way shipping to return it to the "manufacturer"
in California cost me $18, it took over 3 weeks to get it replaced,
and I could buy another "lifetime guaranteed" module locally for $22..

I returned it "just on principal" and couldn't wate for it to be
returned so bought one locally anyway. Now I have an obvsolete brand
new memory module sitting in stock that I'll likely never use, that
effectively cost me $40.