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Phil Allison
Guest
Sat Jan 21, 2012 2:39 am
"Arfa Daily"
Quote:
Then, all of a sudden, the customer comes back to me, and says that the
project has been called off, because their customer, who has a very great
deal of these machines installed in their premises, wants only brand new
boards as replacements, and is not prepared to accept boards that have
been repaired. I asked why this was, and the answer that I got was that
they felt that new boards would be more reliable. No matter how much that
I pointed out that the real life evidence of bathtub curves and infant
mortality, clearly refuted that premise, they were not having any of it.
They seemed unable to understand that a board that has been in service for
a while has passed the infant mortality stage, and is fully burnt in. And
that it is in the main phase of its service life, where any problems are
likely to be random single component failures. None of the parts on this
board were specials, so it could have been repaired to full manufacturer's
spec, using original manufacturer's parts. In fact, the triac that seemed
to be failing could actually have been upgraded to the next one in the
series to *improve* overall reliability.
** You has to supply and therefore warranty the new PCBs ??
Not * YOU * I hope.
I would make the customer purchase all such boards and then you have no
warranty obligation over them.
.... Phil
N_Cook
Guest
Sat Jan 21, 2012 1:34 pm
Arfa Daily <arfa.daily_at_ntlworld.com> wrote in message
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Quote:
"Gareth Magennis" <sound.service_at_btconnect.com> wrote in message
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"Arfa Daily" <arfa.daily_at_ntlworld.com> wrote in message
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"Gareth Magennis" <sound.service_at_btconnect.com> wrote in message
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"N_Cook" <diverse_at_tcp.co.uk> wrote in message
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Arfa Daily <arfa.daily_at_ntlworld.com> wrote in message
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"Stephen Birchall" <stephenbirchall26_at_gmail.com> wrote in message
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No matter how much that I pointed
Quote:
out that the real life evidence of bathtub curves and infant mortality,
clearly refuted that premise, they were not having any of it. They seemed
unable to understand that a board that has been in service for a while has
passed the infant mortality stage, and is fully burnt in. And that it is
in
the main phase of its service life, where any problems are likely to be
random single component failures. None of the parts on this board were
specials, so it could have been repaired to full manufacturer's spec,
using
original manufacturer's parts. In fact, the triac that seemed to be
failing
could actually have been upgraded to the next one in the series to
*improve*
overall reliability.
But here's the really silly bit. Another board in the machine, which I
already repair for them, suffers a faulty tactile switch on a regular
basis.
So I asked if they were going to stop having that repaired as well. Oh no,
they said. We can carry on doing that one, because it's only a replacement
switch. Slowly banging my head on the bench, I asked them why they felt
that
replacing that single switch was any different from replacing a single
triac, and how they felt that a board that was repaired by having that
switch put in, would be any more reliable than a board that had been
repaired by having a triac put in it. There was no answer, because they
really couldn't see the logic ...
To be fair, the guy that I deal with direct, was with me on this, but his
hands were tied from further up the food chain. What bothers me most is
what
happens to all of the faulty boards. Do they just become scrap destined
for
landfill ? Bit of a waste ...
Arfa
I've come across the concept of failure-rate variability over time etc but I
think the term of a bathtub plot is new to me.
Joins the hockeystick, J, bell, and dead-cat bounce
Arfa Daily
Guest
Sat Jan 21, 2012 11:50 pm
"Phil Allison" <phil_a_at_tpg.com.au> wrote in message
news:9nujauFe86U1_at_mid.individual.net...
Quote:
"Arfa Daily"
Then, all of a sudden, the customer comes back to me, and says that the
project has been called off, because their customer, who has a very great
deal of these machines installed in their premises, wants only brand new
boards as replacements, and is not prepared to accept boards that have
been repaired. I asked why this was, and the answer that I got was that
they felt that new boards would be more reliable. No matter how much that
I pointed out that the real life evidence of bathtub curves and infant
mortality, clearly refuted that premise, they were not having any of it.
They seemed unable to understand that a board that has been in service
for a while has passed the infant mortality stage, and is fully burnt in.
And that it is in the main phase of its service life, where any problems
are likely to be random single component failures. None of the parts on
this board were specials, so it could have been repaired to full
manufacturer's spec, using original manufacturer's parts. In fact, the
triac that seemed to be failing could actually have been upgraded to the
next one in the series to *improve* overall reliability.
** You has to supply and therefore warranty the new PCBs ??
Not * YOU * I hope.
I would make the customer purchase all such boards and then you have no
warranty obligation over them.
... Phil
No, I don't have to supply the boards. The whole maintenance operation is
their baby. They were just going to get me to repair the faulty boards that
their engineers swap out in the field, as I already do for many of the other
vending products that they sell and service. I guess they were trying to
save themselves some money over their current practice of buying new
replacement boards from the machine manufacturer. Their customer that uses
the machines in question, is a huge corporate outfit, so I'm willing to bet
that they have a fixed price contract that covers the supply and rental of
the machines with maintenance thrown in. I would further guess that someone
at the supply / maintenance company, who is my customer, worked out that
they could make a lot more money, or better cover their costs, by having me
repair the boards at £xx per board, rather than buying new ones at £4xx per
board, and binning the faulty ones. And then somehow, their customer found
out about their intentions ... :-(
Arfa
Arfa Daily
Guest
Sat Jan 21, 2012 11:53 pm
"N_Cook" <diverse_at_tcp.co.uk> wrote in message
news:jfeb75$rjo$1_at_dont-email.me...
Quote:
Arfa Daily <arfa.daily_at_ntlworld.com> wrote in message
news:7L3Sq.800$HQ1.183_at_newsfe08.ams2...
"Gareth Magennis" <sound.service_at_btconnect.com> wrote in message
news:7sadnXnM1fiHYorSnZ2dnUVZ8gOdnZ2d_at_bt.com...
"Arfa Daily" <arfa.daily_at_ntlworld.com> wrote in message
news:3XSRq.90$6e4.26_at_newsfe05.ams2...
"Gareth Magennis" <sound.service_at_btconnect.com> wrote in message
news:0PidnbmGNpn3bIrSnZ2dnUVZ8jmdnZ2d_at_bt.com...
"N_Cook" <diverse_at_tcp.co.uk> wrote in message
news:jf8kf5$g4e$1_at_dont-email.me...
Arfa Daily <arfa.daily_at_ntlworld.com> wrote in message
news:4GKRq.251$fZ7.209_at_newsfe09.ams2...
"Stephen Birchall" <stephenbirchall26_at_gmail.com> wrote in message
news:ebf68088-ffb4-4967-aa76-0dd217bb332f_at_o9g2000yqa.googlegroups.com
No matter how much that I pointed
out that the real life evidence of bathtub curves and infant mortality,
clearly refuted that premise, they were not having any of it. They seemed
unable to understand that a board that has been in service for a while
has
passed the infant mortality stage, and is fully burnt in. And that it is
in
the main phase of its service life, where any problems are likely to be
random single component failures. None of the parts on this board were
specials, so it could have been repaired to full manufacturer's spec,
using
original manufacturer's parts. In fact, the triac that seemed to be
failing
could actually have been upgraded to the next one in the series to
*improve*
overall reliability.
But here's the really silly bit. Another board in the machine, which I
already repair for them, suffers a faulty tactile switch on a regular
basis.
So I asked if they were going to stop having that repaired as well. Oh
no,
they said. We can carry on doing that one, because it's only a
replacement
switch. Slowly banging my head on the bench, I asked them why they felt
that
replacing that single switch was any different from replacing a single
triac, and how they felt that a board that was repaired by having that
switch put in, would be any more reliable than a board that had been
repaired by having a triac put in it. There was no answer, because they
really couldn't see the logic ...
To be fair, the guy that I deal with direct, was with me on this, but his
hands were tied from further up the food chain. What bothers me most is
what
happens to all of the faulty boards. Do they just become scrap destined
for
landfill ? Bit of a waste ...
Arfa
I've come across the concept of failure-rate variability over time etc but
I
think the term of a bathtub plot is new to me.
Joins the hockeystick, J, bell, and dead-cat bounce
Well, I don't know about that. I was taught it at college over 40 years ago,
so it's not some new fangled concept. If you put the term into Google, you
will get many thousands of hits on the subject, including modern
interpretations.
Arfa
josephkk
Guest
Wed Jan 25, 2012 2:35 am
On Sat, 21 Jan 2012 12:34:13 -0000, "N_Cook" <diverse_at_tcp.co.uk> wrote:
<snip>
Quote:
replacing that single switch was any different from replacing a single
triac, and how they felt that a board that was repaired by having that
switch put in, would be any more reliable than a board that had been
repaired by having a triac put in it. There was no answer, because they
really couldn't see the logic ...
To be fair, the guy that I deal with direct, was with me on this, but his
hands were tied from further up the food chain. What bothers me most is
what
happens to all of the faulty boards. Do they just become scrap destined
for
landfill ? Bit of a waste ...
Arfa
I've come across the concept of failure-rate variability over time etc but I
think the term of a bathtub plot is new to me.
Joins the hockeystick, J, bell, and dead-cat bounce
The bathtub curve has been around for a long time. Some about WW2 era
military reliability books were filled with it. It is still present in
Military reliability calculations.
I got see an interesting example of management think about reliability
some decades ago. There was this high energy density capacitor (at the
time) some 40 uF at 2 kV in a 1" diameter, 4" long package, not
electrolytic! In characterization testing it had about a 400 hour in use
life, it also had something like a 40 percent failure rate in the first 10
to 20 hours. The management started insisting on 168 hours 100 percent
burn in regimen and could not understand why they could not achieve 250
hour operational life. Nobody could convince them, even with test data,
that a 24 hour burn in would give them the 250 hour operational life.
Some Managers.
?-)
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