[rescue] Slightly OT: Bad Cap Saga

[Geoffrey S. Mendelson]

On Mon, Aug 18, 2008 at 11:22:41AM -0700, Curious George wrote:
> You're right.  I started my career in the mid 70's (with the i4004)
> and have *no* experience with "valves", etc.  :>

Actually the i4004 came pretty late in the game. There were all sorts
of computers before that. 

> What *relative* timescales are you talking about?
> The poster was talking about some "spare PC's" that are
> sitting around waiting to replace units that are in service.
> Are you claiming that those *sitting* unpowered will exhibit the
> same failure rate as those that have been *running* for the
> past couple of years (note the model he cited is not a 30 year
> old tube radio!  :> )

Beats me. Since the original problem was a preservative in the electrolyte
(something to keep the goo inside from going bad for the nontechical),
they may just as easily have gone bad sitting around, or not. I have no
information.

Since I assume the "correction" was to include a presevative that worked
better than nothing, but not as well as the original missing item, I'm
even more clueless. Better than nothing and good are far apart, and I
don't know where they decided to stop, or how many attempts were along 
the way.

There are also many different unrelated problems with cheap components
and again, in use or not, such as lubricants drying out or solidifying,
heat sink transfer paste drying out, lithum batteries failing or leaking,
and so on.

A couple of years ago Office Depot brand batteries sold here would in a matter
of months swell to the point they would no longer fit in the device, leak or
both. They have since upgraded from PRC batteries to Singapore ones, and
now they are just short lived crap. 

If the same company that made their batteries made the lithum batteries
that xxxx brand used, they could have the same problem. The electrolyte
in litium batteries is very caustic and could destroy a motherboard.

Cheap PRC battery companies are not the only ones with problems, Sony batteries
used in Apple and Dell laptops had the same problem.


> ***IT*** wasn't a bad wash.  The point of my post was "are there
> any *other* things going on, here?"  Stop fixating on this one
> incident.  50 years hence, will you still be blaming all e-cap
> failurews on some botched industrial espionage attempt in
> Taiwan?  When do you start wondering if, perhaps, something
> *else* has come into play?

It's the root cause of the fall of the capacitor industry in Tiawan. It 
taught them to improve their product to a point and leave it there. Something
the Koreans, Indians, North Koreans, etc will follow.

My wife likes to tell the story of a brand of tomato sauce with mushrooms.
Every month they removed a small amount of mushrooms until their sales 
slowed down. That's where they kept it.

The capacitor problem just taught that lesson to the Tiwanese and it will
spread. I'm sure that in 5 years your Japanese vendors will ask you when
you spec a component, "how long should it last"?


> I make it a point to look at "failed devices".  I want to
> understand *why* they failed.  And, if there is anything that I,
> as a designer, can do to reduce the likelihood of failure in
> the future (and what the tradeoffs to do so might be).

That's a noble idea, and you will do well as long as you stay away
from the "lowest possible price" consumer goods. 



> 
> I'm not only interested in how the electronics failed but how
> mechanically something may have died.  How long that item
> *should* last is a separate issue to me.  Should a Cadillac
> last longer than a Chevy or a Yugo?  <shrug>  Understanding
> how they fail is a skillset I actively develop as it lets me
> add value to the things I work on.

There always will be a niche market for high end items. :-)

> 
> Likewise, I routinely evaluate the firmware and software in
> products.  Especially products that I don't use.  It helps me
> figure out what's good about a design vs. bad.  E.g., this
> past week I played with a dozen LCD monitors.  While the
> "front panel controls" on most were similar, some were
> designed in a clearly inferior manner that made using them
> very unintuitive (and, since I suspect very *few* people
> read the user manual for their monitor, having an intuitive
> interface is *essential*).

Is it? Seriously, how many people buy using price as their sole critera?


> The point of this thread was to ellicit any observations people
> had over what types of failure modes they might be experiencing
> in various bits of kit.

Was it? I thought it was more about busting the urban legend of the bad
capacitors, which it was not. 


> 
> So, your summary contribution is "(still) bad components"
> akin to making 0.245W resistors to save a few micropennies
> per unit (resistor).  OK, then I just avoid Taiwanese
> components and vendors and all is well!  :>

I would not characterize it as a particular ethnic group or country.
Greed and stupidity are universal.

Geoff.

-- 
Geoffrey S. Mendelson, Jerusalem, Israel gsm at mendelson.com  N3OWJ/4X1GM