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'[EE]: Testing Challenge'
2002\07\15@084517 by Russell McMahon

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Here's a hypothetical (let's say) challenge.
Consider it an example of a real world problem.
Please ignore if of no interest.

Problem: Propose a better test method.

A manufacturer of domestic toasters finds that a large (many thousands)
consignment of toasters has a fault.
Many toasters are stored in a central depot but a significant number are now
stored at several scattered locations a significant distance from the main
storehouse. Skilled staff are probably not available at many locations.
Conscientious and intelligent staff are deemed to be present at all
locations (maybe a bad assumption :-) )..

Each toaster has a double pole switch which disconnects the element from
both leads of the mains cord when the toaster is plugged in and not in use.
When the main "toasting handle" is depressed the two pole switch closes,
passing mains power to each side of the element. (In all countries that I
know of, all domestic toasters must have such a switch to meet regulatory
safety requirements). In the faulty batch, in about 5% to 10% of the
toasters, one or other pole of the two pole switch is mechanically jammed on
due to a fault in the design and manufacturing process. The toasters that do
not have this fault are entirely safe and meet all regulatory requirements.
The toasters that do have this fault must be either repaired or scrapped.
Each toaster is packed in a plastic bag and then in a cardboard carton. The
bag is unsealed but to get access to the opening the toaster would have to
be removed from the box. Removal and repacking takes time. The toaster has a
non detachable cord which has a 3 pin plug (Phase, Neutral, Ground pins).
The cord is packed at one end  of the box outside the plastic bag and the
plug is pushed down with the cord. The plug can be pulled out a short
distance to access its pins, if desired, without unpacking the whole cord.
The plug is enclosed in a small plastic bag which is fastened at the cord
end with a small rubber band.

The test must reliably determine, at lowest cost in time and effort,  which
toasters have one switch pole permanently closed so that one or other of the
live leads is connected to the element.

The brute force test solution is to unpack each toaster and test resistance
from a point on the element to each of the two live mains pins.

An alternative is to use sharp probes to poke small holes through the
toasters' main plastic bags and plug bags to achieve the same test. This
could be achieved without full unpacking at lower time cost but with
slightly more skill in manipulating the conductivity tester. The
acceptability small cosmetic damage to each bag by the test leads needs to
be considered.

SO

YOU are asked for a better (faster, cheaper etc) way of doing this test.
What do you propose?



               Russell McMahon.

PS - I have absolutely no official or pecuniary involvement with domestic
toasters :-)

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2002\07\15@092845 by Kevin Blain

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At first glance,

1. capacitance from earth to each of the other two pins.

If either side of the switch is stuck closed, I would expect greater
capacitance to earth from either phase or neutral.


2. mutual inductance to nearby coil

If either side of the switch is stuck, effectively a longer wire exists
as either phase or neutral is joined to the element, and it should be
possible to detect this greater inductance, which will have a lower
resonant frequency, by using a dip oscillator.


My little offering.....

Regards, Kevin

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2002\07\15@094412 by Tim McDonough

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On Tue, 16 Jul 2002 00:46:49 +1200, Russell McMahon wrote:
>Here's a hypothetical (let's say) challenge.
>
>Problem: Propose a better test method.

>SO
>
>YOU are asked for a better (faster, cheaper etc) way of doing this
>test.
>What do you propose?

What is the TFWC (Total Factory Warehouse Cost) of the toaster compared
to the cost of either testing? I recall seeing some toasters that sell
for a retail price of around $14-15US. It may be as cheap to scrap them
all as it is to test and repair them by the time you set up a test
station, write a procedure, and have someone grind through checking and
repacking each one.

Tim

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2002\07\15@095253 by M. Adam Davis

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You could go way expensive and do a time domain reflection test.  Send a
sharp square wave down each wire and wait for the reflection.  The
properties of the wires and elements being known you can calculate the
distance the wave travels in the time it takes to bounce back and
determine whether it's connected or not.

But a really cool "let's not even touch the box' way would be to
determine (experimentally) the resonant frequency of the element
attached to the cord verses seperate elements and cord.  Due to possible
cord winding differences there's a margin of error that may be quite
large, but I suspect that the difference between the two frequencies is
large enough that you could still send a wireless signal to (or through)
the toaster (package and everything) with a sweep through a small range
and determine whether the wire is connected.

This would be more expensive to develop than the first solution, but
would cost less overall.  I expect you could automate it and scan a box
a second if needed.

-Adam

Russell McMahon wrote:

{Quote hidden}

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2002\07\15@100855 by Tal Dayan

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Can we assume that the handles of the packed toasters
are all in the OFF position ?

Tal

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2002\07\15@101058 by Roman Black

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Russell McMahon wrote:
>
> Here's a hypothetical (let's say) challenge.

> Each toaster has a double pole switch which disconnects the element from

> The test must reliably determine, at lowest cost in time and effort,  which
> toasters have one switch pole permanently closed so that one or other of the
> live leads is connected to the element.


Something like an RF "dip" meter, a couple of transistors
and a meter, and one probe. Using the prong like an antenna
and detecting loading. The prong connected to the element
will have a different loading and operate the meter. You
only have to probe 2 prongs.

Or just don't bother fixing them, just ship the lot out to
a third world country, you know, where they just stick wires
in power points with their bare fingers etc.
I've heard some scary stories about construction sites in
China. ;o)
-Roman

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2002\07\15@104053 by Lawrence Lile

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Well, here is how a (hypothetical) real toaster manufacturer does it, if
there was such a hypothetical case involving a hypothetical shorted-out
toaster:

1.  At the end of the production line, as the toasters are produced, perform
a high potential test on the toaster per UL requirements.  This involves
placing 1200 VAC on both hot and neutral terminals of the AC plug, and
touching the other probe of the 1200VAC supply to the ground terminal (if
any- toasters are required to be grounded in Canada and Europe but not in
the US)  and any exposed metal parts such as the case, or screw-heads.  This
hipot test is done to 100% of our toasters before they are boxed and sealed.
Preventing this problem up-front is the absolute cheapest way to solve it.

2. Audit the above test in the factory per Mil Standard 105E or whatever the
current revision is.  Take a statistally signifigant sample of the above
100% tested toasters, unbox them, and hipot test them again.  Probably 2% of
our toasters are retested in this manner. A single hipot failure would cause
rejection of the entire lot being sampled, and would require them all to be
unboxed and 100% tested again.

3. Periodically audit the above lots AGAIN using independant auditors from a
third party source, sort of an audit of the audits.

4. If a problem is found in the field that could potentially harm a
customer, embargo everything in the warehouse, send an audit team manager,
who hires a bunch of temps to unbox the toasters, and supervises training
them to perform the hipot test.  Since the hipot test machine is automatic,
using it requires only two brain cells. Test protocol would vary depending
on how serious the problem is, in this case, 100% of the warehouse inventory
would be unboxed and retested.  Audit team manager may observe the tests
being performed, or sdo his own audits of the procedure, or even bring
trained techs with him for complex procedures.

5. If more failures which could hurt a consumer are found in the above
warehouse audit, a determination of a recall will then be made.  We are
definitely in CPSC territory in this hypothetical case.  The CPSC is the US
Consumer Product Safety Commission.  We are required to report to them any
potentially deadly product that is discovered, and work with them in
determining which models must be recalled, how to notify stores and
consumers, and so on.  This "fine mess" is phenomonally expensive,
time-consuming, and worth it if it keeps people from getting hurt.

Granted this is not the cheapest way to accomplish the test.  But it does
use reliable, proven methods that are in fact required anyway and can be
administered by unskilled personnel.  This is basic stuff to anybody who
ever worked in Quality control, but if you haven't, it may seem like the
wierdest procedure you've ever heard of.

--Lawrence Lile


{Quote hidden}

now
> >stored at several scattered locations a significant distance from the
main
> >storehouse. Skilled staff are probably not available at many locations.
> >Conscientious and intelligent staff are deemed to be present at all
> >locations (maybe a bad assumption :-) )..
> >
> >Each toaster has a double pole switch which disconnects the element from
> >both leads of the mains cord when the toaster is plugged in and not in
use.
> >When the main "toasting handle" is depressed the two pole switch closes,
> >passing mains power to each side of the element. (In all countries that I
> >know of, all domestic toasters must have such a switch to meet regulatory
> >safety requirements). In the faulty batch, in about 5% to 10% of the
> >toasters, one or other pole of the two pole switch is mechanically jammed
on
> >due to a fault in the design and manufacturing process. The toasters that
do
> >not have this fault are entirely safe and meet all regulatory
requirements.
> >The toasters that do have this fault must be either repaired or scrapped.
> >Each toaster is packed in a plastic bag and then in a cardboard carton.
The
> >bag is unsealed but to get access to the opening the toaster would have
to
> >be removed from the box. Removal and repacking takes time. The toaster
has a
> >non detachable cord which has a 3 pin plug (Phase, Neutral, Ground pins).
> >The cord is packed at one end  of the box outside the plastic bag and the
> >plug is pushed down with the cord. The plug can be pulled out a short
> >distance to access its pins, if desired, without unpacking the whole
cord.
> >The plug is enclosed in a small plastic bag which is fastened at the cord
> >end with a small rubber band.
> >
> >The test must reliably determine, at lowest cost in time and effort,
which
> >toasters have one switch pole permanently closed so that one or other of
the
> >live leads is connected to the element.
> >
> >The brute force test solution is to unpack each toaster and test
resistance
> >from a point on the element to each of the two live mains pins.
> >
> >An alternative is to use sharp probes to poke small holes through the
> >toasters' main plastic bags and plug bags to achieve the same test. This
> >could be achieved without full unpacking at lower time cost but with
> >slightly more skill in manipulating the conductivity tester. The
> >acceptability small cosmetic damage to each bag by the test leads needs
to
{Quote hidden}

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2002\07\15@105319 by Russell McMahon

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> Can we assume that the handles of the packed toasters
> are all in the OFF position ?


Yes.

       RM

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2002\07\15@105731 by Russell McMahon

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> Well, here is how a (hypothetical) real toaster manufacturer does it, if
> there was such a hypothetical case involving a hypothetical shorted-out
> toaster:
>
> 1.  At the end of the production line, as the toasters are produced,
perform
> a high potential test on the toaster per UL requirements.  This involves
> placing 1200 VAC on both hot and neutral terminals of the AC plug, and
> touching the other probe of the 1200VAC supply to the ground terminal

As a single contact on the switch is closed the element is connected to one
mains lead BUT still isolated from the case.

This would only work in this instance if the breakdown voltage from element
to case was < 1200 VAC and > the normal mains voltage. The clearances are
such i typical toasters (and, I' imagine, in this hypothetical one :-)    )
that I suspect it may not arc during this test.

I agree that total recall would be best.


       Russell McMahon

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2002\07\15@111205 by Alan B. Pearce

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This sounds rather like you have a real world situation with a product, and
using the hypothetical toasters as an example :)

I am not sure you will be able to do the testing without unwrapping them,
but after that using a cable finder inside the toaster slot and testing for
the signal on the power plug would seem to be the easiest way of doing it.

Another method that just may work. Many current model DVM's have a
capacitance range on them. Using one of these you could get some calibration
values off units that do work satisfactorily for capacitance between
phase/ground and neutral/ground. Each depot that has stock should be able to
obtain locally a similar suitable meter and do the testing with a limited
amount of knowledge, and so should be able to divide their stock into three
piles on the basis of different readings, even if they do not have an
identical meter. A list of readings faxed back to base should allow someone
there to make a definitive decision on which are OK.

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2002\07\15@113314 by Bill & Pookie

picon face
Thinking of the toaster elements as coils and the
cord as an antenna, couple a signal into the box
and see which produces different static on a cheep
am radio.
Or use a dip meter and see if their resonates are
different.


Bill

{Original Message removed}

2002\07\15@125647 by Bob Blick

face picon face
Plug them into a guitar amp and crank up the volume. Hit the toaster.
Listen to the sound from the amp. Reverse polarity and hit again. If you
hear "wire flapping" sounds either time, you have a connection to the
element.

Rock on, dude.

-Bob

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2002\07\15@133523 by Bill & Pookie

picon face
That's it!
Set them on a induction coil that is plugged into
a amp, vibrate them in a magnetic field and see
what key they are tunned to.

Bill

{Original Message removed}

2002\07\15@133735 by Peter L. Peres

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On Tue, 16 Jul 2002, Russell McMahon wrote:

>Here's a hypothetical (let's say) challenge.

Is a bonus hypothetical too ?

>Conscientious and intelligent staff are deemed to be present at all
>locations (maybe a bad assumption :-) )..

Yeah, right.

>The plug is enclosed in a small plastic bag which is fastened at the cord
>end with a small rubber band.
>
>The test must reliably determine, at lowest cost in time and effort,  which
>toasters have one switch pole permanently closed so that one or other of the
>live leads is connected to the element.

I propose that a small two-receptacle mains extender cord be rewired so
each socket will have no ground and the hot and neutral wires would be
reversed in one of them. I'd attach a common cheap DVM on 220Vac scale
between the ground contacts in the double socket, and neutral of the mains
input (the two ground contacts are tied together and insulated from
anything else).

The double socket's cord is inserted into a working mains socket.

Now each unit to be tested is plugged into each socket in turn (two
pluggings per unit), with a reading taken on each plugging. Faulty units
will have a significant difference between the two readings, the
difference will be low on okay units.

The method relies on the leakage resistance and capacitance of a connected
element being higher than that of an unconnected one. The good units will
also show some imbalance in readings that depends on construction (a good
unit should read near 1/2Vmains on both tries).

Another method involves plugging the cord into a HF generator (~300kHz,
100Vpp), with the ground connected to ground this time, and using a small
sniffer (fieldstrength meter) to sniff near the elements through the
plastic (even through all the packaging may be possible).

Peter

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2002\07\15@141154 by Peter L. Peres

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On Mon, 15 Jul 2002, Tal Dayan wrote:

>Can we assume that the handles of the packed toasters
>are all in the OFF position ?

I guess you have to, otherwise unpacking is the only option.

Peter

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2002\07\15@144055 by Lawrence Lile

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> > Can we assume that the handles of the packed toasters
> > are all in the OFF position ?

No, IMHO you must test them both ways, although they should be off in the
packaging.

In fact you MUST operate the handles in both the off and the on position to
completely test the toaster.  Usually this handle pushes down a metal
carriage, which could possibly contact a live electronic part all on it's
own.  BTDTGTTS.

--Lawrence

*Been There, Done That, Got The T-Shirt


----- Original Message -----
From: "Russell McMahon" <apptechSTOPspamspamspam_OUTPARADISE.NET.NZ>
To: <spamBeGonePICLISTSTOPspamspamEraseMEMITVMA.MIT.EDU>
Sent: Monday, July 15, 2002 9:51 AM
Subject: Re: [EE]: Testing Challenge


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2002\07\15@144258 by Lawrence Lile

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Good Point.  I think the standard test also involves hi-potting to an
element wire when the toaster is in the OFF position.

--Lawrence

> As a single contact on the switch is closed the element is connected to
one
> mains lead BUT still isolated from the case.
>
> This would only work in this instance if the breakdown voltage from
element
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2002\07\15@162336 by Bob Ammerman

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How do you handle the case where the carriage comes into contact with a live
part somewhere along its travel, but not at either end. Or something loose
that bounces around and touches the case on odd Wednesdays after 10pm, when
there is a full moon?

Bob Ammerman
RAm Systems

{Original Message removed}

2002\07\15@170841 by Lawrence Lile

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Loose parts are found by shaking the unit.  A loose conductive object is a
critical failure that requires the entire lot to be rejected and
re-inspected for loose parts.  This might be 5000 toasters, so the MFR is
usually very wary about loose parts.

--lawrence

{Original Message removed}

2002\07\15@174717 by Peter L. Peres

picon face
On Mon, 15 Jul 2002, Bob Ammerman wrote:

>How do you handle the case where the carriage comes into contact with a live
>part somewhere along its travel, but not at either end. Or something loose
>that bounces around and touches the case on odd Wednesdays after 10pm, when
>there is a full moon?

I hope he won't answer this, as it's in the 'perpetuum mobile' class.

NOBODY is perfect. Everyone just buys insurance to cover what they think
they will be missing in inspections and qc, plus a little bit for
un-foreseeable situations. Oh, yes, and there is that ISO900x thing.  That
sure makes one perfectly *auditable*. i.e. CYA^1e26. (*)

Peter

(*) CYA = Cover Your A**

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2002\07\15@180406 by Lee Jones

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>>> A manufacturer of domestic toasters finds that a large (many
>>> thousands) consignment of toasters has a fault.

>>> Each toaster has a double pole switch which disconnects the
>>> element from both leads of the mains cord when the toaster is
>>> plugged in and not in use.  When the main "toasting handle"
>>> is depressed the two pole switch closes, passing mains power
>>> to each side of the element.  In the faulty batch, in about
>>> 5% to 10% of the toasters, one or other pole of the two pole
>>> switch is mechanically jammed on due to a fault in the design
>>> and manufacturing process.

>> Can we assume that the handles of the packed toasters
>> are all in the OFF position ?

> Yes.


Use relative, rather than absolute, values of capacitive or
inductive behavior at the plug prongs to assess failed switch.

I believe that the electrical characteristics of either the hot
or neutral lead in one power cord, when measured in relationship
to the ground lead, will be very close if the lead terminates at
a properly (i.e. open) switch.

If one pole of the switch is shorted, then the mated power cord
lead will have significant variance (due to connection of the
heating element) compared to the other lead in that cord.

Specificially, build a small device with a "wall outlet" into
which one toaster is plugged, a "start" button, and pass/fail
result light(s).  Test is as follows:

 0) worker plugs suspect toaster into test device

 1) worker presses start button

 2) check for DC continuity between hot and neutral pins to
    find switches with double fault -- both poles shorted.
    If found, illuminate fail light.

 3) measure capacitive / inductive / resonant frequency of
    hot lead in relationship to ground lead

 4) measure capacitive / inductive / resonant frequency of
    neutral lead in relationship to ground lead

 5) if result values in steps 3 and 4 are similar, then both
    switch poles are open; illuminate pass light.  If result
    values are not identical (i.e. dissimilar), then one pole
    of switch is shorted; illuminate fail light.

 6) when worker sees either light illuminate, they unplug
    toaster and put in proper pass or fail process queue

 7) after 3-5 seconds, test device turns off both lights.
    This step attempts to reduce false results if worker is
    distracted and assumes previous unit's results apply to
    a newly connected unit.  (Better that worker has to test
    a unit twice than a unit slips through without testing.)

Some experimentation is required to determine how close the
values have to be to be "similar" or "dissimilar" in step 5.
Test device only needs short term stability (allowing cheap
components that drift) and no absolute values (allowing high
variability between component values in different test devices).

Minimaly trained workers should be able to do quite a lot of
toasters per hour using the above device & procedure.

And a PIC would be well suited to drive such a test device.
Question now is will the non-recurring engineering cost to
develop & build a small number of testers be low enough, when
combined with labor costs, to justify testing the toasters.

                                               Lee Jones

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2002\07\15@181248 by Mike Singer

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Russell McMahon wrote:
.
.
.
> What do you propose?
.
.
.
  Is this a reply you are waiting for:
  Send these dangerous things to Third
World countries as humanitarian help?
(What actually often happened).

  Regards.   Mike.

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2002\07\15@182105 by Lyle Hazelwood

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> And a PIC would be well suited to drive such a test device.
> Question now is will the non-recurring engineering cost to
> develop & build a small number of testers be low enough, when
> combined with labor costs, to justify testing the toasters.

As opposed, perhaps, to toasting the testers?

Sorry folks, I just couldn't resist that one. 8^)
Lyle

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2002\07\15@182931 by Brendan Moran

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> > And a PIC would be well suited to drive such a test device.
> > Question now is will the non-recurring engineering cost to
> > develop & build a small number of testers be low enough, when
> > combined with labor costs, to justify testing the toasters.

Personally, I'd say a box-full of nano-robots is the solution.  Just upend
it in the warehouse in question, give em an hour or so, and presto-changeo,
you have toasters that work!!

> As opposed, perhaps, to toasting the testers?
>
> Sorry folks, I just couldn't resist that one. 8^)

Likewise

--BJM

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2002\07\15@192434 by Harold M Hallikainen

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       It seems that the heating element would have significant capacity to
ground since the coils cover a large area. How about measuring capacity
at the power plug, line to ground, and neutral to ground? I'd expect a
unit with a stuck switch to have considerably higher capacity. Hopefully
this is considerably higher than random variations due to cord bundling,
etc.  You could just plug the plug into a tester and not have to remove
the bag around the toaster.

Harold


FCC Rules Online at http://hallikainen.com/FccRules
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2002\07\15@200603 by Bob Ammerman

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----- Original Message -----
From: "Lawrence Lile" <TakeThisOuTllilespamspamTOASTMASTER.COM>
To: <PICLISTEraseMEspamMITVMA.MIT.EDU>
Sent: Monday, July 15, 2002 5:06 PM
Subject: Re: [EE]: Testing Challenge


> Loose parts are found by shaking the unit.

Ah... a nice scientific testing regimen.     ;-)

Bob Ammerman
RAm Systems

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2002\07\16@054750 by Russell McMahon

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flavicon
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OK - here's "The Answer"
As this is, of course, entirely hypothetical there is no one correct answer,
but here's my take on it.

I was highly impressed by all the suggestions. Tine domain reflectometry,
resonance, even mechanical resonance, inductance, induced
charge/fields/other. Many solutions may well have worked well. Some were
indeed entirely non invasive.

My own solution which works like a charm on the (entirely hypothetical)
toasters is to use capacitance measurement (exactly as some suggested).

Take a 3 pin mains socket with a short length (50 mm) of cord and two short
wires A & B. . Connect Phase & Neutral to wire A and earth to wire B .
Connect A & B to capacitance inputs on multimeter.

For each toaster extract plug out of end of box and plug into cord end with
prongs pressing through bag.. This slots the small plastic bag. It is most
unlikely that customers will notice and less likely that they will care. If
desired the bag could be removed for the test.

A good toaster has a capacitance of about 180 pF (hyp-pF? :-) ) when the
toast handle is up and around 300 pF when depressed. The up readings and the
down readings are consistent within a few pF giving a very clear test.

A bad toaster with one wire always connected to one of the two mains leads
has a reading of about 300 pF with handle up and varies by about 2 or 3 pF
with handle down.

QED.

Consistent results were obtained on a sample of about 30 good toasters and
constant capacitance results on two sample faulty ones. A casual stroll
through the toaster section of a local reseller toting a power socket
equipped tester showed that the wide capacitance variation between up and
down was present in all 15 or so models present. In all cases it was easy to
predict whether the handle was up or down based on "up" capacitance alone -
even without a "standardisation" pretest. This was true for models with from
2 to 6 slice capability.

As none were (apparently) faulty I could not establish how they would act in
this mode but have no great reason to think that they would not exhibit very
small capacitance change in that mode.

Next challenge ? :-)


       Russell McMahon

Peter probably does not get a hypothetical fee as whistle blowers are
usually not paid.

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2002\07\16@092534 by Sean H. Breheny

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Hi Russell,

I am really curious to know what motivated this challenge? I had thought
that it was similar to some problem you are actually facing. Did you
actually make the measurements you mention in this email?

Sean

At 09:47 PM 7/16/2002 +1200, you wrote:
{Quote hidden}

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2002\07\16@115103 by Bob Barr

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On Tue, 16 Jul 2002 21:47:39 +1200, Russell McMahon wrote:

<snip>
>
>Consistent results were obtained on a sample of about 30 good toasters and
>constant capacitance results on two sample faulty ones. A casual stroll
>through the toaster section of a local reseller toting a power socket
>equipped tester showed that the wide capacitance variation between up and
>down was present in all 15 or so models present. In all cases it was easy to
>predict whether the handle was up or down based on "up" capacitance alone -
>even without a "standardisation" pretest. This was true for models with from
>2 to 6 slice capability.
>

I can hardly imagine the conversation you would have had with store
security if they had seen you testing their toasters. :=)


Regards, Bob

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2002\07\16@115942 by Alan B. Pearce

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>I can hardly imagine the conversation you would have had with
>store security if they had seen you testing their toasters. :=)

Yeah, no wonder us engineers have trouble getting pay rises with these
weirdo's around :)))

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2002\07\17@032516 by Mike Singer

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  Russell, are you joking again?
  You see, there are a lot of people, who seriously took your challenge. The only Lawrence Lile replied absolutely correctly:
.
> We are definitely in CPSC territory in this hypothetical
> case.  The CPSC is the US Consumer Product Safety
> Commission.  We are required to report to them any
> potentially deadly product that is discovered, and work
> with them in determining which models must be recalled,
> how to notify stores and consumers, and so on.  This
> "fine mess" is phenomonally expensive, time-consuming,
> and worth it if it keeps people from getting hurt.
.
  May be I'm missing something due to my insufficient command of English. Regardless of what you can catch with domain reflectometry, resonance, even mechanical resonance, inductance, induced charge/fields/other, _ALL_ suspicious devices should be recalled, reassembled and retested at factory shops. Until it goes about countries where human life costs nothing.
(my country for example). In this case it makes no sence to bother with this f..cking switches at all.    Even from the point of common sense all these methods are of no use. Since they _DO NOT PASS_ devices, with switches that conduct your AC under your conditions and pass others. At factory shops we should _PASS OVER ONLY_ devices with switches that do not conduct under wide range of conditions.
  Don't blame me hardly, If I've missed something.
  Regards.   Mike.

Russell McMahon wrote:
{Quote hidden}

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2002\07\17@141358 by Peter L. Peres

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On Tue, 16 Jul 2002, Russell McMahon wrote:

>
>        Russell McMahon
>
>Peter probably does not get a hypothetical fee as whistle blowers are
>usually not paid.

Translate please. In what sense am I a whistle blower ?

Peter

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