[rescue] Slightly OT: Bad Cap Saga
Geoffrey S. Mendelson
gsm at mendelson.com
Mon Aug 18 01:05:20 CDT 2008
On Sun, Aug 17, 2008 at 02:48:36PM -0700, Curious George wrote:
> I've never seen such a margin *published* by a vendor. Instead,
> WVDC was always the "rated specification" for the component
> (e.g., unlike something like TTL that you *can* run on 7VDC
> despite it being designed for a nominal 5V supply). "Best
> practices" always have you seriously derating the specs on
> things like caps for exactly this reason. (of course, the
> things I design/build are intended for longer service lives
> so I can't play fast and loose with choice of components :-/ )
Published by a vendor, or told to you by the manufacturer if you asked.
Without meaning to sound racist, I doubt that if YOU asked the question,
you would get an answer. Things told over a meal with the guy down the
street are very different to customers on the phone or in the conference
I don't know about the Chinese, but I had a very expensive lesson in
"the deal is not really signed until we get drunk together" with the
president of a Korean company, you probably have 20-30 products of
in your home, or items containing parts made by them.
> I don't know how one could even *try* to design that way!
Oh come off it. You do it every day. I'm sure that you have design
limitations and you try to minimize cost by staying at the edge of
those limitiations. You just have a different understanding of those
> I.e., you would have to spend considerable effort characterizing
> the parts you buy (you being the actual manufacturer) so you
> could be sure the units would pass *your* outgoing inspection!
> Or, are you saying that the original manufacturer (*not* the
> company who's name is on the OUTSIDE of the piece of equipment)
> makes no warranties to *its* customer (i.e., the company who
> will ultimately sell to John Doe)?
Yes. The price for untested items is significant lower than the
cost of tested ones. Statistical testing (testing every 5th, 100th,
1000th) raises the price less, but still costs as if a unit fails,
you either toss the ones since the previous test, or test each one.
If you buy a consumer item, let's say a DVD player from Wal-Mart, you
have no idea of where or how it was made, the working conditions and
age of the workers who made it, and so on. You have no more desire to
know about it than to know that hambuger you ate for lunch used to walk
around and moo.
If this DVD player dies in the first 90 days, you take it back to Wal-Mart
and they trash it. Trashing 1 out of 1000 or whatever the expected rate
is was included in their cost calculation. It's probably cheaper than
having a local technician look at it, let alone repair it, and far cheaper
than shipping it back to Long March and having them examine it to determine
why it failed.
If it fails afer 90 days, you buy another one. If you were upset by the
short life, you buy another brand, or go to another store. If you do, I'll
bet you never look far enough to find out they all say Long March DVD
player company in small print on the circuit boards in Chinese, or even
could read it if you looked.
> Or, do these folks operate in an environment where they never
> have to "pay" for their mistakes (i.e., through repairs and/or
> lost business due to bad reputation, etc.)
Do you know anyone that shops at Wal-Mart? Ask them what they think
of the store, the service, the products, and so on. Does a negative
opinion stop them?
Geoffrey S. Mendelson, Jerusalem, Israel gsm at mendelson.com N3OWJ/4X1GM
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