[rescue] Slightly OT: Bad Cap Saga
jorge234q at yahoo.com
Tue Aug 19 12:02:17 CDT 2008
--- On Mon, 8/18/08, Geoffrey S. Mendelson <gsm at mendelson.com> wrote:
> On Mon, Aug 18, 2008 at 12:17:51PM -0700, Curious George
> > I don;'t care *where* the number comes from -- as long as
> > the vendor stands behind it (and we have recourse as to
> > how to respond when/if this ever becomes untrue).
> > When we meet with Japanese vendors, it is very unnerving
> > trying to get them to give you specifics about design
> > limits. They always want to know what we "want it to be".
> > Perhaps this is a cultural issue -- I think Americans are
> > used to working to specifications whereas the Japanese
> > seem to be geared to working to *your* specifications!
> Not at all. They are following the time honored system of
> selling to spec. They make an item and sell it to you based
> upon your specs.
No, different issue entirely. The device didn't exist -- we
wanted them to make one for us. Since we were unfamiliar with the
tradeoffs involved in *that* design process, we couldn't on our
own come up with specs that would have ensured an economical design.
By way of an arbitrary (and fictional!) example: imagine you're
asking them to design a thermal printhead assembly. This is
little more than a bunch of resistors with digital switches
controlling each individually.
>From the physical (thermal?) standpoint, all you care about is
the dimensions of the element and getting a certain amount of heat
out of it in a certain time interval.
So, a zero-th order approach says "pick an R and specify V to get
the desired amount of power dissipation".
But, as V goes up, there are consequences to the switching devices
(i.e., must have higher breakdown voltages). As V goes down (because
R has been picked as a lower value), there are *other* consequences
for the same electronics (e.g., I goes up).
What's *their* (manufacturer) process technology like? What's the
sweet spot for the control electronics?
What ramifications does this have to the geometry of the resistive
devices? Does it affect the technology used to deposit them on
the "printing surface"? Does it affect reliability? Does it
affect the cycle time of the elements (thermally)? etc.
The cost of learning this is far outweighed by the "cost" of
outsourcing the problem completely. So, what you're wanting is
to engage in an *engineering* "give-and-take" (i.e., a dynamic
design process) with the supplier to figure out how to find that
sweet spot. Obviously, the changes made in the printhead's
design will have ramifications to the rest of the system -- things
that the supplier will not be aware of (hence, he's in the same
boat as you -- except the mirror image problem!).
I found that American firms are much easier to get into this
"give-and-take" sort of specification process. The Japanese
seem to want to "do what you want" (and just adjust their
> > When I started designing products, I used to factor in a 3%
> > warranty cost (i.e. 3% of DM+DL -- so the actual factor
> > was fairly less than this). Over the years, experience has
> > taught me how to work that down to a fraction of a percent.
> But at what cost? If you are buying Matsushita components,
> you are paying a lot more for them than entire boards from the
> "Long March DVD Player and Hoisin Sauce Company".
The cost of replacing/repairing a "bad board" (hence, a
"defective product") can easily outweigh the value of the
I recall one medical device designed many years ago where the
cost of the device (DM+DL) was less than half the cost of
sending someone "down the road" (locally) to repair it!
For those devices that you can't just place in a cardboard
box and *mail* complete replacements, you *really* don't want
to have to put someone on a plane, etc. to troubleshoot and
(and that's assuming your customer is content with the day
or three that this will take)
> > I don't have that experience when the components, labor,
> > assemblies, etc. I am given are of unknown quality. Given
> > time (years?), I imagine I could apply the same statistical
> > processes to *learn* what those new factors would be -- but,
> > in your scenario, it seems likely that they could vary
> > widely from vendor (supplier) to vendor.
> Usually not as much as you think. Unless it is defective, cheap crap
> has the same failure rate world over.
This suggests the failure rate is driven solely by the quality
of the components? (or, that the production quality of all of
these houses are virtually identical)?
> However most people don't even
> bother, they find someone to manufacture it for them, and
> often they design it for you.
> I prefer Flextronics (the world's largest manufacturer
> of cell phones) personally, but obviously companies like the "Long
> March DVD Player and Hoisin Sauce" company exist and do well.
> > So, presumably, people (actuaries?) at these firms have developed
> > their own characterizations for *their* products using *their*
> > vendors/suppliers. Are they wed to key suppliers? Or, do
> > they take a (statistical) gamble each time they opt to
> > purchase a subassembly from some new/other firm?
> Pretty much. So does the consumer. One of the things you
> find out living here
I take it you are on the rim?
> is that there are many subcontractors designing and
> manufacturing laptops.
> If you buy a Dell or HP in the U.S., it may come from any
> one of them.
> When you bring it here, you find that submodel was never
> imported here and there are no parts for it. :-(
> Obviously parts which are subcontracted out, e.g. hard
> disks, RAM, batteries, chargers, etc are all the same, but
> internally they are very different.
Yeah -- except they all SNAP together with those frigging
flimsy snaps!! :-/
> However spreading out your manufacturing spreads out you
> > By your comment, they don't test their work before they sell it
> > to me. I pay real money for their products and then resell
> > or integrate them into my own products. *I*, dealing with the
> > end user, give a warranty (since that is expected, even if
> > a silly 90 day wonder).
> Well I'm sure they would gladly test each unit if you wanted them to.
> How much are you willing to pay for the service? You might even find
> someone who would actually test them instead of writing a computer
> program that fakes the test reports. :-)
Exactly. When your (my) reputation stands to win/lose based on the
quality of the product, you want some reassurances that your
suppliers are as committed to making (not FAKING) a good product
as you are. :<
> > Now, I reask my question:
> > "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.)"
> > When I go to said Taiwanese firm, do they just smile and
> > say, "So sorry..."? Do they never have to pay for their
> > problems? Sure, *I* will stop using them as a supplier
> > and will probably gladly recount my less than wonderful
> > experiences with them... are you saying life just goes
> > on for them without any repurcusions?
> And who would you tell? Are you going to call the buyer at
> the competition?
> Are you going to call the buyer at Wall-Mart, or Costco?
No, but, IME, the Industry (pick an industry!) is always much
smaller than you can imagine. I.e. "word gets around" by
whatever means. People change jobs and bring their horror
stories with them, etc.
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