FUSES (was Re: 2 Fried G210's in a single day :-(

> me frying my drives puts me in
> the .05% bracket of human capability ...

Ha !

I was thinking of popping one with 440 just to make the top of the
list all by myself !

But, in all seriousness, and in sincere appreciation, your problem
has shown us all a few things.

#1) regardless of the emphasis in the documentation, put all safety
precautions into your design.

#2) TEST with extra safetys. I assume that the lightbulb test would
have prevented the multiple failures? I was wondering if one could
put on a bunch of LED's instead of the stepper to verify operation?

#3) check and re-check all of the connectors. Many of us are home
hobbyists and can ill afford replacing one Gecko let alone 8!

#4) TEST THE CAP's. yes we all have played the trick of the toilet
paper tube with aluminum foil and a TINY cap to shock our friends (or
kill people with pace makers) so we should already know caps can
store HUMONGOUS amounts of electricity. funny how we strap ourselves
in when working on $.50 IC's but are cavalier with $100.00 drives.

and Marriss does take life lightly, who else would recognize that
some resistors pursue existential goals ?

With the 470uf/100V caps running at about $3.00 maybe Marriss might
buy 1,000 and offer them with the Gecko's. at 1,000 lots they have
got to get cheaper.

And now for the question. FUSES.

the 5x20 or 1/4 inch fuses are used in snap in holders, cheap ones
can spread like RCA jacks, or are available in in-wire styles (ugly)
or in neat DIN rail (expensive) blocks.

The plug in fuses like automotive fuses offer a more secure
installation, but are not readily available in board mounts styles
(personal rant)

What is the preferred fuse holder method ?


Dave

--- In CAD_CAM_EDM_DRO@y..., "audiomaker2000" <audiomaker@s...> wrote:
> Hmmmm, Well... I was pretty happy with Mariss until he announced to
> the world that me frying my drives puts me in the .05% bracket of
> human capability :-/ (or is that 2 drives at .025%) !!!!
>
> (sigh)
>
> Send some more Mariss, I have my Mig welder all powered up and
ready
> to go as the supply!!
>
> Sean
>
>
> --- In CAD_CAM_EDM_DRO@y..., "mariss92705" <mariss92705@y...> wrote:
> > Hi,
> >
> > I've been following this thread with attention, so before
replying
> I
> > decided to research my "deep-fried gecko" database to see what
> light
> > it would shed. I looked up the results for the last 12 months,
> April
> > 2001 to April 2002.
> >
> > In that time period 6,813 geckos shipped out and 129 came back
> fried.
> > That is an unadjusted failure rate of about 1.9%, which is not
too
> > good until it is analyzed further.
> >
> > Every returned drive is tested and the cause of the failure is
> > entered into a database. This discards about 110 drives because
> > typically 1/2 of the drives I see coming back have no
discoverable
> > problem. Of the 129 "fried" ones, every effort is made to
> determine
> > the precipitating event that led to failure.
> >
> > Of the 129 that were actually fried, 69 were determined to be
user
> > induced failures. Some were truly spectacular, such as the 2 that
> had
> > 115VAC and the one that had 230VAC applied to the power supply
> inputs.
> >
> > As probably everyone knows by now, we have a "one time stuff
> happens"
> > deal. This means a drive is replaced one time, no charge, no
> matter
> > the reason. All that is required is a full confession as to what
> > happened along with the dead drive. This helps me to see what the
> > common mistakes are.
> >
> > Of the remaining 60 drives, it was not possible to determine with
> > certainty what precipitated the failure with 38 of them. Either
> they
> > were too badly damaged to do a forensic examination or the
failure
> > was of such a nature that it could not conclusively proved to be
> > caused by the user.
> >
> > That leaves 22 drives where the fault was entirely ours. Here
> there
> > were logic ICs that got bored doing Boolean algebra, capacitors
> that
> > wanted to be short circuits and resistors that felt infinite ohms
> > should be their existential goal. Throw in a cracked PCB trace
> that
> > only reveals itself with board flexure, a solder-paste joint that
> > failed to wet an IC pin and cold wave-soldered joint because
> > someone's guacamole got on the board. That pretty much runs the
> gamut
> > for these 22 failures.
> >
> > I then compared these failure rates against our OEM accounts
> versus
> > individual end-users. Our mix is about 70% OEM versus 30%
> > individuals. OEM by our definition is someone that uses more than
> 100
> > drives a year and incorporates them into a product they
> manufacture.
> > Some numbers shifted dramatically here.
> >
> > User induced or undeterminable failures were 19* drives out of
> 4,680
> > OEM units shipped, or 0.4%. Non-user induced failures (our fault)
> > were 12 units, for a failure rate of 0.25%. This is a much more
> > tolerable number.
> >
> > Mariss
> >
> >
> > *The user-induced failure of 19 drives was skewed by one OEM
> customer
> > that had a bad (shorted turn) motor in their incoming inspection
> test
> > stand. The receiving inspector went thru 8 drives before someone
> > thought there might be a problem here. They sent the motor to me
> as a
> > trophy after things got straightened out. To my knowledge, it has
> > killed more geckos than any other motor I know of.
> >
> >
> > --- In CAD_CAM_EDM_DRO@y..., beer@s... wrote:
> > > On 7 May, CAD_CAM_EDM_DRO@y... wrote:
> > >
> > > > All the problems I had appeared to be due to false contacts
on
> > motor
> > > > leads (two times) or a spike on the motor connection when
> > plugging
> > > > the fuse into its socket (the caps were still loaded ... ).
> > >
> > > > I'm a product designer and in my job I know an important
rule:
> > every
> > > > product should be designed with a reasonable fault tolerance.
> > >
> > >
> > > There are limits to what constitutes "reasonable". Certainly,
> > asking
> > > the Gecko to survive a roaring fire would not be considered
> > reasonable
> > > by most people. Asking the Gecko to survive being run over by a
> > > bulldozer would also not meet most people's reasonable test.
> > >
> > > Well, the electrical nastiness you've imposed ( most likely as
a
> > result
> > > of arcing ) would very likely be placed in the same class as
the
> > above
> > > examples by many electronics designers.
> > >
> > > It may seem like a small thing to you, but to others it's a
> really
> > big
> > > thing.
> > >
> > > For myself, being basically poor, I'd rather have the most
> stripped
> > down
> > > ( and therefore lowest cost ) unit possible and then simply be
> VERY
> > > careful.
> > >
> > > When I feel the need for insurance, I buy a completed finished
> > product
> > > with a warranty.
> > >
> > > Alan
> > >
> > >
> > > --
> > >
> > > Alan Rothenbush | The Spartans do not ask the
> number
> > of the
> > > Academic Computing Services | enemy, only where they are.
> > > Simon Fraser University |
> > > Burnaby, B.C., Canada | Agix of
> > Sparta