Current rating of an RJ45 connection

[Joerg]

Folks,

Have to send 12V/500mA across a connection. So far there is only an
RJ45. Looking at datasheets I saw current ratings of 1.2A and 1.5A which
sounds like a lot.

Is this kosher? I know PoE sends up to 600mA across but I've always felt
uneasy about it when they went up from the (older?) 350mA.

--
Regards, Joerg

http://www.analogconsultants.com/

[Jamie]

Joerg wrote:

> Folks,
>
> Have to send 12V/500mA across a connection. So far there is only an
> RJ45. Looking at datasheets I saw current ratings of 1.2A and 1.5A which
> sounds like a lot.
>
> Is this kosher? I know PoE sends up to 600mA across but I've always felt
> uneasy about it when they went up from the (older?) 350mA.
>

it's not the wire you need to worry about it's the cheap crimp style
connectors.

[Joe Chisolm]

On Tue, 28 Aug 2012 17:57:17 -0700, Joerg wrote:

> Folks,
>
> Have to send 12V/500mA across a connection. So far there is only an
> RJ45. Looking at datasheets I saw current ratings of 1.2A and 1.5A which
> sounds like a lot.
>
> Is this kosher? I know PoE sends up to 600mA across but I've always felt
> uneasy about it when they went up from the (older?) 350mA.

A company I deal with has 2 products that do 5V/500mA on a RJ45. The
products have different types of RJ45s. One is a Dual stacked with a
EMI shell. The other one has an internal vert RJ45. No problems with
either one. I have tested the stacked RJ45 with 5V/1A out of
a bench supply for most of a day, just as kind of a torture test.
No noticeable issues.

(that was only 1 of the connectors on the dual)


--
Chisolm
Republic of Texas

[lang...@fonz.dk]

On Aug 29, 2:57 am, Joerg <inva...@invalid.invalid> wrote:
> Folks,
>
> Have to send 12V/500mA across a connection. So far there is only an
> RJ45. Looking at datasheets I saw current ratings of 1.2A and 1.5A which
> sounds like a lot.
>
> Is this kosher? I know PoE sends up to 600mA across but I've always felt
> uneasy about it when they went up from the (older?) 350mA.
>

I think I remember PoE as something like ~400-500mA per pair, but
that's gotta
be including everything from connectors, wire size and how many cables
that are
usually packed together in a large installation

-Lasse

[CharlieB]

> Have to send 12V/500mA across a connection. So far there is only an RJ45. Looking at datasheets I saw current ratings of 1.2A and 1.5A which sounds like a lot.

Amphenol make a range of connectors rated at 1.5A and I've successfully used them in NRTL listed POE powered products drawing >800mA

Charlie

[k...@att.bizzzzzzzzzzzz]

Don't forget distance. PoE is one of the few times I've had to worry about
"maximum power transfer". BTW, 400-500mA sounds right but my memory is a bit
fuzzy on that, too.

[Nico Coesel]

Joerg <inv...@invalid.invalid> wrote:

>Folks,
>
>Have to send 12V/500mA across a connection. So far there is only an
>RJ45. Looking at datasheets I saw current ratings of 1.2A and 1.5A which
>sounds like a lot.
>
>Is this kosher? I know PoE sends up to 600mA across but I've always felt
>uneasy about it when they went up from the (older?) 350mA.

RJ45 isn't the best connector. In my experience you need to reseat the
connector after a few years for it to make good contact. IMHO sending
a lot of current through it may make things worse. BTW PoE always uses
two parallel wires to carry the supply to the device whether the power
is phantom fed or through unused pairs.

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
--------------------------------------------------------------

[lang...@fonz.dk]

On Aug 29, 2:54 pm, "k...@att.bizzzzzzzzzzzz"
<k...@att.bizzzzzzzzzzzz> wrote:
> On Wed, 29 Aug 2012 01:04:40 -0700 (PDT), "langw...@fonz.dk"

sure distance matters when you need to figure out how much power you
have left at the
of the cable, but it doesn't affect current rating

-Lasse

[Joerg]

Nico Coesel wrote:
> Joerg <inv...@invalid.invalid> wrote:
>
>> Folks,
>>
>> Have to send 12V/500mA across a connection. So far there is only an
>> RJ45. Looking at datasheets I saw current ratings of 1.2A and 1.5A which
>> sounds like a lot.
>>
>> Is this kosher? I know PoE sends up to 600mA across but I've always felt
>> uneasy about it when they went up from the (older?) 350mA.
>
> RJ45 isn't the best connector. In my experience you need to reseat the
> connector after a few years for it to make good contact. IMHO sending
> a lot of current through it may make things worse. BTW PoE always uses
> two parallel wires to carry the supply to the device whether the power
> is phantom fed or through unused pairs.
>

Thanks, Nico. Also thanks to all others. One of the things concerning me
is the fact that datasheets derate to zero milliamps at slightly above
70C. Got that info this morning and it was quite the surprise. This is
from the connector we are using:

http://www.te.com/commerce/DocumentDelivery/DDEController?Action=showdoc&DocId=Specification+Or+Standard%7F108-1163%7FE%7Fpdf%7FEnglish%7FENG_SS_108-1163_E.pdf

The unit will sit in full sun occasionally and can become as hot as the
inside of a car under that condition.

[Jeff Liebermann]

On Tue, 28 Aug 2012 17:57:17 -0700, Joerg <inv...@invalid.invalid>
wrote:

>Have to send 12V/500mA across a connection. So far there is only an
>RJ45. Looking at datasheets I saw current ratings of 1.2A and 1.5A which
>sounds like a lot.
>
>Is this kosher? I know PoE sends up to 600mA across but I've always felt
>uneasy about it when they went up from the (older?) 350mA.

Note that the maximum recommended current (for power conduction) per
wire for #24AWG CAT5e is 577ma.
<http://www.powerstream.com/Wire_Size.htm>

I found some references to a TIA recommendation for 360ma per pin
maximum, but never could find the original document.

One of the cleanup jobs I dealt with had 12V at about 600ma going
through an RJ45 as in PoE but not using 802.3af power control.
(Actually, it was an RJ50 connector, which is the 10 pin version of
the RJ45). The problem was that after about 20 insertion and removal
cycles, the power connectors were becoming intermittent. Examination
with my microscope shows pits, craters, holes, missing plating, and
evidence of arcing. The problem was that the connector was being
inserted and removed with power applied. The load looked like a BFC
(big fat capacitor) which produced current spikes well above the
recommended 360ma. A peak current limiting resistor in series with
the power connections was the best I could do to reduce the problem to
acceptable levels.

While working on the problem, I got diverted into measuring how much
gold was being plated onto the RJ45 pins. The better connectors have
50 micro inches. The junk connectors I bought on eBay barely had 10
micro inches with exposed nickel plating in places. I also had issues
with surface roughness, which reduced the contact area and seemed to
cause some intermittents without arcing:
<http://rj45s.com/Gold_Plating_Problems.html>
(This site is worth reading if you're using RJ45 connectors).



--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[Joerg]

Jeff Liebermann wrote:
> On Tue, 28 Aug 2012 17:57:17 -0700, Joerg <inv...@invalid.invalid>
> wrote:
>
>> Have to send 12V/500mA across a connection. So far there is only an
>> RJ45. Looking at datasheets I saw current ratings of 1.2A and 1.5A which
>> sounds like a lot.
>>
>> Is this kosher? I know PoE sends up to 600mA across but I've always felt
>> uneasy about it when they went up from the (older?) 350mA.
>
> Note that the maximum recommended current (for power conduction) per
> wire for #24AWG CAT5e is 577ma.
> <http://www.powerstream.com/Wire_Size.htm>
>

You can get 22AWG TP for that. Usually only two-pair but that would
suffice here.

> I found some references to a TIA recommendation for 360ma per pin
> maximum, but never could find the original document.
>

I found 1.2A as a low value at 25C, so far. But the surprise was a
rather fast derating to almost zero at 70C.

> One of the cleanup jobs I dealt with had 12V at about 600ma going
> through an RJ45 as in PoE but not using 802.3af power control.
> (Actually, it was an RJ50 connector, which is the 10 pin version of
> the RJ45). The problem was that after about 20 insertion and removal
> cycles, the power connectors were becoming intermittent. Examination
> with my microscope shows pits, craters, holes, missing plating, and
> evidence of arcing. The problem was that the connector was being
> inserted and removed with power applied. The load looked like a BFC
> (big fat capacitor) which produced current spikes well above the
> recommended 360ma. A peak current limiting resistor in series with
> the power connections was the best I could do to reduce the problem to
> acceptable levels.
>

The worst is a BFC on the source side plus a BFC on the other side and
the only inrush limiter is a short cable and an RJ45 connection ...
bzzzt ... *PHUT*

But we'll avoid that here.

> While working on the problem, I got diverted into measuring how much
> gold was being plated onto the RJ45 pins. The better connectors have
> 50 micro inches. The junk connectors I bought on eBay barely had 10
> micro inches with exposed nickel plating in places. I also had issues
> with surface roughness, which reduced the contact area and seemed to
> cause some intermittents without arcing:
> <http://rj45s.com/Gold_Plating_Problems.html>
> (This site is worth reading if you're using RJ45 connectors).
>

Thanks! I have bookmarked it. In this case we'd be ok because there
would be essentially only two insertions. One at production test and
another at site installation. Both non-powered.

[Adrian Jansen]

We regularly see plastic boxes supposedly rated for 85 degC badly
deformed after being in a car in Australia.

--
Regards,

Adrian Jansen adrianjansen at internode dot on dot net
Note reply address is invalid, convert address above to machine form.

[Jeff Liebermann]

On Wed, 29 Aug 2012 11:11:18 -0700, Joerg <inv...@invalid.invalid>
wrote:

>Jeff Liebermann wrote:
>> On Tue, 28 Aug 2012 17:57:17 -0700, Joerg <inv...@invalid.invalid>
>> wrote:
>>
>>> Have to send 12V/500mA across a connection. So far there is only an
>>> RJ45. Looking at datasheets I saw current ratings of 1.2A and 1.5A which
>>> sounds like a lot.
>>>
>>> Is this kosher? I know PoE sends up to 600mA across but I've always felt
>>> uneasy about it when they went up from the (older?) 350mA.
>>
>> Note that the maximum recommended current (for power conduction) per
>> wire for #24AWG CAT5e is 577ma.
>> <http://www.powerstream.com/Wire_Size.htm>
>>
>
>You can get 22AWG TP for that. Usually only two-pair but that would
>suffice here.

Careful. That's #22AWG solid, not stranded. Stranded CAT5 is #24AWG
which is what you'll probably see on "portable" equipment.

>> I found some references to a TIA recommendation for 360ma per pin
>> maximum, but never could find the original document.

>I found 1.2A as a low value at 25C, so far. But the surprise was a
>rather fast derating to almost zero at 70C.

That's odd. The only thing I can think of is that either the plastic
connector or the insulation becomes sufficiently soft to cold flow.
That reduces the pressure on the insulation displacement connection,
possibly resulting in a smaller contact area between the stake and the
wire. (This is a guess, this is only a guess).

>The worst is a BFC on the source side plus a BFC on the other side and
>the only inrush limiter is a short cable and an RJ45 connection ...
>bzzzt ... *PHUT*

That's exactly what I had. I don't know how big the cazapitor was
inside the power supply as it would have required explosives to
disassemble. However, the device had about 10,000uF across the PS
input pins:
12V at 0.6A = 20 ohms
t = RC = 20 * 0.01F = 200msec
which was enough to keep the device alive during minor power glitches.
The designer wanted to add more energy storage but ran out PCB real
estate. A supercap would have been better, but at the time, they were
rather pricy.

>But we'll avoid that here.

Hopefully, it's running on battery, solar, or something not
susceptible to power outages and glitches. If not, run a test to see
how long your device will fly without power. You may want to do some
inrush current limiting.

>Thanks! I have bookmarked it. In this case we'd be ok because there
>would be essentially only two insertions. One at production test and
>another at site installation. Both non-powered.

Assumption, the mother of all screwups. The first indication of a
problem showed up in final test, where one power supply and I/O cable
combination was used to connect to the automagic test equipment. After
about an hour of testing, the ATE was rejecting nearly every device
due to intermittent and "noisy" connections. I traced it to the RJ45
connectors and stupidly supplied the test line with a box of 25
replacement cables. That lasted about a week. I knew I was in
trouble when I got a casual email requesting more cables.

[Joerg]

Jeff Liebermann wrote:
> On Wed, 29 Aug 2012 11:11:18 -0700, Joerg <inv...@invalid.invalid>
> wrote:
>
>> Jeff Liebermann wrote:
>>> On Tue, 28 Aug 2012 17:57:17 -0700, Joerg <inv...@invalid.invalid>
>>> wrote:
>>>
>>>> Have to send 12V/500mA across a connection. So far there is only an
>>>> RJ45. Looking at datasheets I saw current ratings of 1.2A and 1.5A which
>>>> sounds like a lot.
>>>>
>>>> Is this kosher? I know PoE sends up to 600mA across but I've always felt
>>>> uneasy about it when they went up from the (older?) 350mA.
>>> Note that the maximum recommended current (for power conduction) per
>>> wire for #24AWG CAT5e is 577ma.
>>> <http://www.powerstream.com/Wire_Size.htm>
>>>
>> You can get 22AWG TP for that. Usually only two-pair but that would
>> suffice here.
>
> Careful. That's #22AWG solid, not stranded. Stranded CAT5 is #24AWG
> which is what you'll probably see on "portable" equipment.
>

True, but the 577mA of 24AWG suffice in this case.

>>> I found some references to a TIA recommendation for 360ma per pin
>>> maximum, but never could find the original document.
>
>> I found 1.2A as a low value at 25C, so far. But the surprise was a
>> rather fast derating to almost zero at 70C.
>
> That's odd. The only thing I can think of is that either the plastic
> connector or the insulation becomes sufficiently soft to cold flow.
> That reduces the pressure on the insulation displacement connection,
> possibly resulting in a smaller contact area between the stake and the
> wire. (This is a guess, this is only a guess).
>

We just did a test run. Stays under 60C. Whew ...

>> The worst is a BFC on the source side plus a BFC on the other side and
>> the only inrush limiter is a short cable and an RJ45 connection ...
>> bzzzt ... *PHUT*
>
> That's exactly what I had. I don't know how big the cazapitor was
> inside the power supply as it would have required explosives to
> disassemble. However, the device had about 10,000uF across the PS
> input pins:
> 12V at 0.6A = 20 ohms
> t = RC = 20 * 0.01F = 200msec
> which was enough to keep the device alive during minor power glitches.
> The designer wanted to add more energy storage but ran out PCB real
> estate. A supercap would have been better, but at the time, they were
> rather pricy.
>

10,000uF across RJ45 pins? Wow! That is brazen.

>> But we'll avoid that here.
>
> Hopefully, it's running on battery, solar, or something not
> susceptible to power outages and glitches. If not, run a test to see
> how long your device will fly without power. You may want to do some
> inrush current limiting.
>

We'll have a generator with uC triggered starts as needed to replenish a
large battery. So always juice. But the battery will not directly feed
the system, there's a current limiter.

>> Thanks! I have bookmarked it. In this case we'd be ok because there
>> would be essentially only two insertions. One at production test and
>> another at site installation. Both non-powered.
>
> Assumption, the mother of all screwups. The first indication of a
> problem showed up in final test, where one power supply and I/O cable
> combination was used to connect to the automagic test equipment. After
> about an hour of testing, the ATE was rejecting nearly every device
> due to intermittent and "noisy" connections. I traced it to the RJ45
> connectors and stupidly supplied the test line with a box of 25
> replacement cables. That lasted about a week. I knew I was in
> trouble when I got a casual email requesting more cables.
>

That's probably the same feeling people get when a request comes in via
collect call, "Dad, I'd need another $500, soon" :-)

[Jeff Liebermann]

On Wed, 29 Aug 2012 16:55:32 -0700, Joerg <inv...@invalid.invalid>
wrote:

>We just did a test run. Stays under 60C. Whew ...

What will it do when it's out in the real world? 60C - 25C ambient is
a 35C temp rise. That's not too awful, but with a "commercial"
temperature range of 0 - 70C, that's 105C on the case. That should
boil the tea on your product case.

>10,000uF across RJ45 pins? Wow! That is brazen.

Yep. (Disclaimer: It wasn't my design). The designer originally had
a much smaller cazapitor. However, the initial customers experienced
problems with noise on the power line. Rather than fix it in the
power supply (there were several thousand already in stock), he
applied the fix in the device by adding a huge cazapitor. Nobody
noticed a problem until final test started rejecting devices. Better
power supplies were eventually purchased, but the BFC and my
thermistor fix remained.

Incidentally, it wasn't my responsibility to fix the RJ45 problem. I
was doing the FCC type acceptance dry run(s), and was asked to "take a
look" at the problem. That somehow morphed into inheriting a
production engineering function. It was a safe thing to do for the
company as I was working on a fixed price contract and would not get
paid extra for fixing their connector problem.

[Jasen Betts]

On 2012-08-29, Adrian Jansen <adr...@qq.vv.net> wrote:

>> from the connector we are using:
>>
>> http://www.te.com/commerce/DocumentDelivery/DDEController?Action=showdoc&DocId=Specification+Or+Standard%7F108-1163%7FE%7Fpdf%7FEnglish%7FENG_SS_108-1163_E.pdf
>>
>> The unit will sit in full sun occasionally and can become as hot as the
>> inside of a car under that condition.
>>
> We regularly see plastic boxes supposedly rated for 85 degC badly
> deformed after being in a car in Australia.

I've seen 85 degC capacitors (I assume it was the cap) quit in similar circumstances
When I parked I had to unplug the blinker unit and put it under the
seat so that it would stay cool. I never got round to replacing the
cap with a 105 degree part.

--
⚂⚃ 100% natural

--- Posted via news://freenews.netfront.net/ - Complaints to ne...@netfront.net ---

[SoothSayer]

The connector rating and the spec for a given data streaming schema
including power are two different things.

Of course the connectors will have a higher rating than any circuit one
would design using them.

The wire is the big factor. The spec should be below the gauge standard
as well.

So, never use small wire RJ-45 for a long run. Get the 24 or 22 Ga
stuff.

These connectors connect at the very end of the wire, usually using a
pair of barbs into the wire/strand bundle. That will likely carry far
more than they are actually even rated at. They usually end up
practically gas tight as well. Certainly if one pots or molds onto it.

Our cat 6 stuff gets an RJ-45 shaped shroud over it, connected to the
drain line/shield during fabrication. Makes for a better eye.

Eye eye.

[SoothSayer]

On Wed, 29 Aug 2012 12:58:19 GMT, ni...@puntnl.niks (Nico Coesel) wrote:

>RJ45 isn't the best connector. In my experience you need to reseat the
>connector after a few years for it to make good contact.

All the Gold utilized has changed all that.

Hundreds of billions of normal air connections made every day (all
around the world), and years later still fine. And there is nobody
wandering around flexing all the lines either. Gold does not oxidize at
any rate you would understand. Obviously. Platinum, practically never.

Your experience must have been with tinned 'stingers' on CB radios.

Cat 5 and 6 say for the last 15 years, has been just fine as far as
contact issues go.

And half an amp is trivial.

[legg]

On Wed, 29 Aug 2012 09:33:58 -0700, Joerg <inv...@invalid.invalid>
wrote:

This could simply mean that a change in colour or surface finish of
the casing is required. Different colours and materials have different
albedo qualities.

White is three times better than grey, order of magnitude+ better than
black.

RL

[Joerg]

Not sure if the difference is that stark in real life. I own a white car
and a couple of weeks ago during really hot summer days I had a black
Volkswagen rental. I didn't feel that much of a difference when coming
back to the parked car after severak hours.

[Joerg]

Jeff Liebermann wrote:
> On Wed, 29 Aug 2012 16:55:32 -0700, Joerg <inv...@invalid.invalid>
> wrote:
>
>> We just did a test run. Stays under 60C. Whew ...
>
> What will it do when it's out in the real world? 60C - 25C ambient is
> a 35C temp rise. That's not too awful, but with a "commercial"
> temperature range of 0 - 70C, that's 105C on the case. That should
> boil the tea on your product case.
>

Most of this civilian computer stuff isn't really geared towards harsh
life. Even garden tools aren't. I had a shovel with plastic handle where
the top plastic layer had softened, discolored and became soft. I didn't
notice until the stuff was stuck to my paws.

>> 10,000uF across RJ45 pins? Wow! That is brazen.
>
> Yep. (Disclaimer: It wasn't my design). The designer originally had
> a much smaller cazapitor. However, the initial customers experienced
> problems with noise on the power line. Rather than fix it in the
> power supply (there were several thousand already in stock), he
> applied the fix in the device by adding a huge cazapitor. Nobody
> noticed a problem until final test started rejecting devices. Better
> power supplies were eventually purchased, but the BFC and my
> thermistor fix remained.
>

I am surprised this BFC ever made it through a design review. Or maybe
the ECO was just rubber-stamped and robo-signed :-)

> Incidentally, it wasn't my responsibility to fix the RJ45 problem. I
> was doing the FCC type acceptance dry run(s), and was asked to "take a
> look" at the problem. That somehow morphed into inheriting a
> production engineering function. It was a safe thing to do for the
> company as I was working on a fixed price contract and would not get
> paid extra for fixing their connector problem.
>

One of the reasons I don't do fixed bid work :-)

[lang...@fonz.dk]

On 30 Aug., 18:48, Joerg <inva...@invalid.invalid> wrote:
> legg wrote:

> > On Wed, 29 Aug 2012 09:33:58 -0700, Joerg <inva...@invalid.invalid>
> > wrote:
>
> >> Nico Coesel wrote:

> >>> Joerg <inva...@invalid.invalid> wrote:
>
> >>>> Folks,
>
> >>>> Have to send 12V/500mA across a connection. So far there is only an
> >>>> RJ45. Looking at datasheets I saw current ratings of 1.2A and 1.5A which
> >>>> sounds like a lot.
>
> >>>> Is this kosher? I know PoE sends up to 600mA across but I've always felt
> >>>> uneasy about it when they went up from the (older?) 350mA.
> >>> RJ45 isn't the best connector. In my experience you need to reseat the
> >>> connector after a few years for it to make good contact. IMHO sending
> >>> a lot of current through it may make things worse. BTW PoE always uses
> >>> two parallel wires to carry the supply to the device whether the power
> >>> is phantom fed or through unused pairs.
>
> >> Thanks, Nico. Also thanks to all others. One of the things concerning me
> >> is the fact that datasheets derate to zero milliamps at slightly above
> >> 70C. Got that info this morning and it was quite the surprise. This is
> >>from the connector we are using:

> >>http://www.te.com/commerce/DocumentDelivery/DDEController?Action=show...

>
> >> The unit will sit in full sun occasionally and can become as hot as the
> >> inside of a car under that condition.
>
> > This could simply mean that a change in colour or surface finish of
> > the casing is required. Different colours and materials have different
> > albedo qualities.
>
> > White is three times better than grey, order of magnitude+ better than
> > black.
>
> Not sure if the difference is that stark in real life. I own a white car
> and a couple of weeks ago during really hot summer days I had a black
> Volkswagen rental. I didn't feel that much of a difference when coming
> back to the parked car after severak hours.
>

mythbuster tried it, think they saw a difference of 10'F
between black and white car

-Lasse

[legg]

On Thu, 30 Aug 2012 09:48:41 -0700, Joerg <inv...@invalid.invalid>
wrote:

Really. So then you've got nothing to worry about.

Solar contribution to thermals ia roughly a kilowatt per square meter
in the direct overhead case.

RL

This message has been purged of all expletives or any sentences
containing them.

[Jeff Liebermann]

On Thu, 30 Aug 2012 09:52:37 -0700, Joerg <inv...@invalid.invalid>
wrote:

>Most of this civilian computer stuff isn't really geared towards harsh
>life.

I beg to differ. Although most of the stuff I work with is rated from
0 to 70C, reality has a way of exceeding the specifications. For
example, realistic automotive temperature spec is -40C to about 100C
(or more). Engine compartments get very hot.
<http://en.wikipedia.org/wiki/Operating_temperature>
Recently, we attached a disposable temperature data logger into an
aluminum radio case and let it run for most of salmon season. It went
well over 100C for extended periods when the sun was shining directly
on the case. The vessel owner also complained that his iPod blew up
when left sitting on the top of the same radio. He blamed RF from the
radio, but it was more likely fried by excessive heating.
Incidentally, when I did an autopsy on the radio, most of the screws
had rattled loose. I should have also attached a vibration and
accelerometer data logger.

>Even garden tools aren't. I had a shovel with plastic handle where
>the top plastic layer had softened, discolored and became soft. I didn't
>notice until the stuff was stuck to my paws.

Clever design. Wrap the handle with duct tape. Most such things are
designed for a specific useful life. I suspect (but can't prove) that
research has been performed into reducing the life of plastics under
the guise of having the plastic break down in the landfill. While it
seems a worthy area of research, I suspect that such plastics would
also deteriorate before they reach the landfill. A modest example is
the simulated rubber coating used to simulate a real rubber handle on
some hand held tools (e.g. Sears IR thermometer) and your shovel. It
is designed to turn to sticky mush after about 3-4 years, which is
just about right to insure that none are returned under warranty. I
found that ordinary rubbing alcohol does a tolerable job of removing
the sticky goo without affecting the underlying plastic (usually ABS).
I've seen similar controlled failure designs in the selection of
electrolytic capacitor voltage ratings and power transistor thermal
cycle calculations. It's fairly easy to predict the onset of such
component failures.
<http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx>

>I am surprised this BFC ever made it through a design review. Or maybe
>the ECO was just rubber-stamped and robo-signed :-)

What design review? I don't want to go into excessive detail, but
basically the design was purchased from a consultant in India and
rushed into manufacture without adequate testing. First to market and
cost were the overriding concerns. There were plenty of other things
wrong with it. I was sweating blood because the independent
certification lab was complaining that they couldn't make it pass Part
15 Class A without major modifications. My job was to make these
major modifications, but not change anything, since the product was
being manufactured and stockpiled pending approval. Other engineers
working on the device used this as an opportunity to fix a few things,
which required my approval since it affected the type certification.
That made me effectively in charge of coordinating everything and
guaranteed that I would be blamed if anything went wrong. The BFC fix
was added under my watch. Things went amazingly smoothly. The
certification lab was able to generate the required FCC paperwork.
Changes were made that didn't involve a PCB revision. There was some
grumbling over the necessary rework. No real problems until the RJ45
arcing problem appeared.

>One of the reasons I don't do fixed bid work :-)

That's one mistake I haven't made since. It's an open invitation for
abuse as I learned the hard way. However, I created my own problem. I
could have said "it's not my job" and let someone else handle it. I
was thinking that I could play hero and impress management
sufficiently to get more work from the company. That didn't happen.

[legg]

On Wed, 29 Aug 2012 09:33:58 -0700, Joerg <inv...@invalid.invalid>
wrote:

Oh, yeah - don't get fahrenheit and centigrade mixed up. This tends to
happen in anecdotal conversation with Americans.

RL

[Joerg]

Sure, but there is also re-radiation and reflection. Except maybe for a
Hell Angels Harley or a low-rider rap mobile, vehicles are normally not
painted a dull "primer black". It's more metallic-anthracite plus a
shiny clear coat on top.

> RL
>
> This message has been purged of all expletives or any sentences
> containing them.

But I didn't use any :-)

[Joerg]

Jeff Liebermann wrote:
> On Thu, 30 Aug 2012 09:52:37 -0700, Joerg <inv...@invalid.invalid>
> wrote:
>
>> Most of this civilian computer stuff isn't really geared towards harsh
>> life.
>
> I beg to differ. Although most of the stuff I work with is rated from
> 0 to 70C, reality has a way of exceeding the specifications. For
> example, realistic automotive temperature spec is -40C to about 100C
> (or more). Engine compartments get very hot.

And some automotive engineers should have their head examined. On one
car a module that controlled some stuff in the engine was literally
mounted on top of the engine. Sometiems on hot days the van would refuse
to start ...

The starter on my wife's Corolla just died. Where did they put it?
Between intake manifold and engine! Unreachable, and gets hot there.

> <http://en.wikipedia.org/wiki/Operating_temperature>
> Recently, we attached a disposable temperature data logger into an
> aluminum radio case and let it run for most of salmon season. It went
> well over 100C for extended periods when the sun was shining directly
> on the case. The vessel owner also complained that his iPod blew up
> when left sitting on the top of the same radio. He blamed RF from the
> radio, but it was more likely fried by excessive heating.
> Incidentally, when I did an autopsy on the radio, most of the screws
> had rattled loose. I should have also attached a vibration and
> accelerometer data logger.
>

I was taught very early on that eveything on a boat must be nicely
strapped in and will corrode away in no time. And that stainless doesn't
really mean stainless.

>> Even garden tools aren't. I had a shovel with plastic handle where
>> the top plastic layer had softened, discolored and became soft. I didn't
>> notice until the stuff was stuck to my paws.
>
> Clever design. Wrap the handle with duct tape. Most such things are
> designed for a specific useful life. I suspect (but can't prove) that
> research has been performed into reducing the life of plastics under
> the guise of having the plastic break down in the landfill. While it
> seems a worthy area of research, I suspect that such plastics would
> also deteriorate before they reach the landfill. A modest example is
> the simulated rubber coating used to simulate a real rubber handle on
> some hand held tools (e.g. Sears IR thermometer) and your shovel. It
> is designed to turn to sticky mush after about 3-4 years, which is
> just about right to insure that none are returned under warranty. I
> found that ordinary rubbing alcohol does a tolerable job of removing
> the sticky goo without affecting the underlying plastic (usually ABS).

This one is soft goo stuff all through :-(

> I've seen similar controlled failure designs in the selection of
> electrolytic capacitor voltage ratings and power transistor thermal
> cycle calculations. It's fairly easy to predict the onset of such
> component failures.
> <http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx>
>
>> I am surprised this BFC ever made it through a design review. Or maybe
>> the ECO was just rubber-stamped and robo-signed :-)
>
> What design review? I don't want to go into excessive detail, but
> basically the design was purchased from a consultant in India and

> rushed into manufacture without adequate testing. ...


Ah, a design from Outsourcia :-)


> ... First to market and

> cost were the overriding concerns. There were plenty of other things
> wrong with it. I was sweating blood because the independent
> certification lab was complaining that they couldn't make it pass Part
> 15 Class A without major modifications. My job was to make these
> major modifications, but not change anything, since the product was
> being manufactured and stockpiled pending approval. Other engineers
> working on the device used this as an opportunity to fix a few things,
> which required my approval since it affected the type certification.
> That made me effectively in charge of coordinating everything and
> guaranteed that I would be blamed if anything went wrong. The BFC fix
> was added under my watch. Things went amazingly smoothly. The
> certification lab was able to generate the required FCC paperwork.
> Changes were made that didn't involve a PCB revision. There was some
> grumbling over the necessary rework. No real problems until the RJ45
> arcing problem appeared.
>
>> One of the reasons I don't do fixed bid work :-)
>
> That's one mistake I haven't made since. It's an open invitation for
> abuse as I learned the hard way. However, I created my own problem. I
> could have said "it's not my job" and let someone else handle it. I
> was thinking that I could play hero and impress management
> sufficiently to get more work from the company. That didn't happen.
>

If someone insists on fixed but I either insist on cast-in-concrete
specs plus change-order procedure, or decline. Since neither is desired
by clients it's all by the hour for me.

[lang...@fonz.dk]

On 30 Aug., 23:12, Joerg <inva...@invalid.invalid> wrote:
> Jeff Liebermann wrote:

> > On Thu, 30 Aug 2012 09:52:37 -0700, Joerg <inva...@invalid.invalid>

> > wrote:
>
> >> Most of this civilian computer stuff isn't really geared towards harsh
> >> life.
>
> > I beg to differ.  Although most of the stuff I work with is rated from
> > 0 to 70C, reality has a way of exceeding the specifications. For
> > example, realistic automotive temperature spec is -40C to about 100C
> > (or more).  Engine compartments get very hot.
>
> And some automotive engineers should have their head examined. On one
> car a module that controlled some stuff in the engine was literally
> mounted on top of the engine. Sometiems on hot days the van would refuse
> to start ...
>
> The starter on my wife's Corolla just died. Where did they put it?
> Between intake manifold and engine! Unreachable, and gets hot there.
>

I've fixed the starter on few corollas and getting that thing
unbolted
down behind the engine can drive you nuts

the fix is simple, there's even a cheap kit for it, the thing that
break
is the "switch" inside, basically two pieces of copper angle that
gets
shorted via a copper disc when the started gear is engaged
one of them gets eaten away, buy the kit or bend a piece of copper
and
it will run for another 10 years

-Lasse

[Joerg]

lang...@fonz.dk wrote:
> On 30 Aug., 23:12, Joerg <inva...@invalid.invalid> wrote:
>> Jeff Liebermann wrote:
>>> On Thu, 30 Aug 2012 09:52:37 -0700, Joerg <inva...@invalid.invalid>
>>> wrote:
>>>> Most of this civilian computer stuff isn't really geared towards harsh
>>>> life.
>>> I beg to differ. Although most of the stuff I work with is rated from
>>> 0 to 70C, reality has a way of exceeding the specifications. For
>>> example, realistic automotive temperature spec is -40C to about 100C
>>> (or more). Engine compartments get very hot.
>> And some automotive engineers should have their head examined. On one
>> car a module that controlled some stuff in the engine was literally
>> mounted on top of the engine. Sometiems on hot days the van would refuse
>> to start ...
>>
>> The starter on my wife's Corolla just died. Where did they put it?
>> Between intake manifold and engine! Unreachable, and gets hot there.
>>
>
> I've fixed the starter on few corollas and getting that thing
> unbolted
> down behind the engine can drive you nuts
>

With my arm size I don't see the slightest chance to reach in there
unless I take the whole intake manifold off instead of just the air
filter. Looks like I have to pay for a tow and have it fixed at a shop.
Because it's an automatic there is no way to get the car started. All
there is is that telltale loud click.

> the fix is simple, there's even a cheap kit for it, the thing that
> break
> is the "switch" inside, basically two pieces of copper angle that
> gets
> shorted via a copper disc when the started gear is engaged
> one of them gets eaten away, buy the kit or bend a piece of copper
> and
> it will run for another 10 years
>

Yup, seen it in a Youtube video. Most likely one of the copper pieces
has sailed off because no matter how often I try it will not establish
contact and crank.

Hurumph ... grumble ... grumble ...

[lang...@fonz.dk]

On 30 Aug., 23:57, Joerg <inva...@invalid.invalid> wrote:

yep that's the symptoms, some times a great big wack with a piece of
wood
will make it work a few times

it's only held on with two 8mm bolts from the end, afair the problem
is that
you can't see what you are doing

>
> > the fix is simple, there's even a cheap kit for it, the thing that
> > break
> > is the "switch" inside, basically two pieces of copper angle that
> > gets
> > shorted via a copper disc when the started gear is engaged
> > one of them gets eaten away, buy the kit or bend a piece of copper
> > and
> > it will run for another 10 years
>
> Yup, seen it in a Youtube video. Most likely one of the copper pieces
> has sailed off because no matter how often I try it will not establish
> contact and crank.
>

one of them gets eroded by the sparking I guess, eventually it is so
thin
the disc can't reach it

-Lasse

[Nico Coesel]

Interestingly the color we see doesn't matter. Paint can have totally
different properties at different wavelengths. There is black paint
which is 'white' if you look at it with an infrared camera.

[Nico Coesel]

SoothSayer <SayS...@TheMonastery.org> wrote:

>On Wed, 29 Aug 2012 12:58:19 GMT, ni...@puntnl.niks (Nico Coesel) wrote:
>
>>RJ45 isn't the best connector. In my experience you need to reseat the
>>connector after a few years for it to make good contact.
>
> All the Gold utilized has changed all that.
>

> Cat 5 and 6 say for the last 15 years, has been just fine as far as
>contact issues go.

You obviously never had to run an IT department. Connector problems
cause 99% of the failures. And a network often had quite a few
connectors between the switch and the device. In most cases one cable
from the switch to the patch panel and then one cable from the outlet
to the PC. That is 4 RJ45 connectors between the switch and a PC!

[Joerg]

They looked more like 6mm to me. Problem is that at least one needs to
be loosened from underneath the car and the wire from the start relay
also connects from below. There is all sorts of structurally important
stuff between that and the bottom, no way I can reach that. What a pain.

>>> the fix is simple, there's even a cheap kit for it, the thing that
>>> break
>>> is the "switch" inside, basically two pieces of copper angle that
>>> gets
>>> shorted via a copper disc when the started gear is engaged
>>> one of them gets eaten away, buy the kit or bend a piece of copper
>>> and
>>> it will run for another 10 years
>> Yup, seen it in a Youtube video. Most likely one of the copper pieces
>> has sailed off because no matter how often I try it will not establish
>> contact and crank.
>>
>
> one of them gets eroded by the sparking I guess, eventually it is so
> thin
> the disc can't reach it
>

This was all so easy on my old Citroen 2CV. You could reach just about
anything directly.

[Joerg]

Nico Coesel wrote:
> SoothSayer <SayS...@TheMonastery.org> wrote:
>
>> On Wed, 29 Aug 2012 12:58:19 GMT, ni...@puntnl.niks (Nico Coesel) wrote:
>>
>>> RJ45 isn't the best connector. In my experience you need to reseat the
>>> connector after a few years for it to make good contact.
>> All the Gold utilized has changed all that.
>>
>> Cat 5 and 6 say for the last 15 years, has been just fine as far as
>> contact issues go.
>
> You obviously never had to run an IT department. Connector problems

> cause 99% of the failures. ...


Not really. People do. At least that's what IT pros told me.

Best one was in the late 80's, the days of coax Ethernet. "But I needed
a 50ohm terminator real quick!"

[...]

[k...@att.bizzzzzzzzzzzz]

It does matter, however it's not all that matters. A black (optically) car
will absorb more energy in the visible range than a white car. As you point
out, what it does in the IR range can't be deduced by the "color" in the
visible range.

[lang...@fonz.dk]

I did all from the top standing next to the car, problem was turning
bolt one turn at a time with a spanner feeling the way, can't remember
if a socket wouldn't fit or I just didn't have one

once you have two bolts off you can get out to where it is easy to get
the rest off

-Lasse

[Joerg]

I just called someone who recommended a local shop so I'll do the
decadent thing and just have it done. The American Corollas have all
sorts of emissions control stuff hovering over the engine. It looks like
an aircraft engine in there. Without taking a lot of that off I couldn't
even reach in to feel a socket wrench into position.

[Jeff Liebermann]

On Thu, 30 Aug 2012 14:11:52 -0700, Joerg <inv...@invalid.invalid>
wrote:

>And some automotive engineers should have their head examined. On one
>car a module that controlled some stuff in the engine was literally
>mounted on top of the engine. Sometiems on hot days the van would refuse
>to start ...

It probably works ok when the vehicle is moving and there's plenty of
air flow. The thermostatically controlled fan on the radiator will
help with the air flow when it's not moving. There was a program to
reduce the amount of copper (wire) used in automobiles a few years
ago. I suspect mounting the black box on the engine is one of those
copper saving measures[1]. Part of this is my nightmare come true:
<http://en.wikipedia.org/wiki/42-volt_electrical_system>

>The starter on my wife's Corolla just died. Where did they put it?
>Between intake manifold and engine! Unreachable, and gets hot there.

Ever get the feeling that some vehicles were never designed to be
repaired by mere mortals? There are only so many places on an engine
where one can locate a starter motor along the circumference of the
flywheel.

>I was taught very early on that eveything on a boat must be nicely
>strapped in and will corrode away in no time. And that stainless doesn't
>really mean stainless.

Stainless on stainless has the amazing ability to be self corrosive.
<http://yarchive.net/electr/galvanic_corrosion.html>
In fact, stainless steel can be both anodic and cathodic
to ITSELF. This means that a single piece of stainless
can act as a galvanic battery and promote its own corrosion.
Corrosion in a marine environment is tricky but not impossible. Marine
radios tend to be fairly well protected. However, in the distant
past, I designed parts of the AN/SRD-21 and 22 direction finders for
the US Coast Guard. Aluminum box and stainless hardware initially did
a great job of corroding everything together. The big surprise was
that nobody ever told us that the radios were going to mounted on the
exposed bridge of a 42 footer. Standard procedure is to hose down
everything with a "clean" water hose. A 60 PSI water jet can do an
amazing amount of damage to the front of a radio, such as cave in the
displays and shred the loudspeaker.

Tying down everything on a vessel is required as the rolling motion of
the vessel will eventually turn any loose articles into flotsam or
jetsam.

>This one is soft goo stuff all through :-(

I've experimented with various potions trying to harden the goo. No
luck yet. It's an amazingly common problem. I won't buy anything
with a simulated rubber painted coating as most of them disintegrate
eventually.

>> What design review? I don't want to go into excessive detail, but
>> basically the design was purchased from a consultant in India and
>> rushed into manufacture without adequate testing. ...
>
>Ah, a design from Outsourcia :-)

Nope, Elbonia:
<http://www70.homepage.villanova.edu/matthew.liberatore/dilbert/elbonia.htm>
One of the other engineers wore the hat and beard to a meeting. The
design was quite good for the amount of time allowed. However, the
company also had the PCB and packaging done in India. While the
design company was sufficiently experienced in circuit design to do a
decent job, the packaging and PCB layout were a mess, and may have
been done by a sub-contractor. Both eventually had to be redone.
That's also the source of the RJ45 arcing problem.

Incidentally, the original package was an amazing example of a box
that could only be built by left-handed assemblers. I didn't believe
it until I tried it myself.

>If someone insists on fixed but I either insist on cast-in-concrete
>specs plus change-order procedure, or decline. Since neither is desired
>by clients it's all by the hour for me.

I'm a bottom feeder, cleaning up the mess of others, doing what nobody
wants to do, and deal mostly with dysfunctional companies. Nobody
hires me because I'm the best. They hire me because they're in a
hurry, desperate, cheap, need a scapegoat, or completely clueless.
Most commonly, I get involved when there's a feud between two
departments that are not on speaking terms. If I were to insist on an
air tight definition of completion, the endless negotiations necessary
to finalize a contract would take forever. I've picked up a few
consulting jobs after a reputable consultant burned up too much time
in negotiations.

[1] Everything is a conspiracy.

[Joerg]

Jeff Liebermann wrote:
> On Thu, 30 Aug 2012 14:11:52 -0700, Joerg <inv...@invalid.invalid>
> wrote:
>
>> And some automotive engineers should have their head examined. On one
>> car a module that controlled some stuff in the engine was literally
>> mounted on top of the engine. Sometiems on hot days the van would refuse
>> to start ...
>
> It probably works ok when the vehicle is moving and there's plenty of
> air flow. The thermostatically controlled fan on the radiator will
> help with the air flow when it's not moving. There was a program to
> reduce the amount of copper (wire) used in automobiles a few years
> ago. I suspect mounting the black box on the engine is one of those
> copper saving measures[1]. Part of this is my nightmare come true:
> <http://en.wikipedia.org/wiki/42-volt_electrical_system>
>

I think the 42V stuff has fizzeld, as expected. But mounting electronics
on top of a motor is real stupidity, one just does not do that.

>> The starter on my wife's Corolla just died. Where did they put it?
>> Between intake manifold and engine! Unreachable, and gets hot there.
>
> Ever get the feeling that some vehicles were never designed to be
> repaired by mere mortals? There are only so many places on an engine
> where one can locate a starter motor along the circumference of the
> flywheel.
>

In this case there would have been space towards the radiator, but ...

>> I was taught very early on that eveything on a boat must be nicely
>> strapped in and will corrode away in no time. And that stainless doesn't
>> really mean stainless.
>
> Stainless on stainless has the amazing ability to be self corrosive.
> <http://yarchive.net/electr/galvanic_corrosion.html>
> In fact, stainless steel can be both anodic and cathodic
> to ITSELF. This means that a single piece of stainless
> can act as a galvanic battery and promote its own corrosion.
> Corrosion in a marine environment is tricky but not impossible. Marine
> radios tend to be fairly well protected. However, in the distant
> past, I designed parts of the AN/SRD-21 and 22 direction finders for
> the US Coast Guard. Aluminum box and stainless hardware initially did
> a great job of corroding everything together. The big surprise was
> that nobody ever told us that the radios were going to mounted on the
> exposed bridge of a 42 footer. Standard procedure is to hose down
> everything with a "clean" water hose. A 60 PSI water jet can do an
> amazing amount of damage to the front of a radio, such as cave in the
> displays and shred the loudspeaker.
>

Ouch!

[...]

>>> What design review? I don't want to go into excessive detail, but
>>> basically the design was purchased from a consultant in India and
>>> rushed into manufacture without adequate testing. ...
>> Ah, a design from Outsourcia :-)
>
> Nope, Elbonia:
> <http://www70.homepage.villanova.edu/matthew.liberatore/dilbert/elbonia.htm>

:-)

> One of the other engineers wore the hat and beard to a meeting. The
> design was quite good for the amount of time allowed. However, the
> company also had the PCB and packaging done in India. While the
> design company was sufficiently experienced in circuit design to do a
> decent job, the packaging and PCB layout were a mess, and may have
> been done by a sub-contractor. Both eventually had to be redone.
> That's also the source of the RJ45 arcing problem.
>
> Incidentally, the original package was an amazing example of a box
> that could only be built by left-handed assemblers. I didn't believe
> it until I tried it myself.
>

Sounds like the Toyota here, except you also need skinny arms.

[...]

[Jeff Liebermann]

On Thu, 30 Aug 2012 22:18:39 GMT, ni...@puntnl.niks (Nico Coesel)

wrote:

>SoothSayer <SayS...@TheMonastery.org> wrote:
>
>>On Wed, 29 Aug 2012 12:58:19 GMT, ni...@puntnl.niks (Nico Coesel) wrote:
>>
>>>RJ45 isn't the best connector. In my experience you need to reseat the
>>>connector after a few years for it to make good contact.
>>
>> All the Gold utilized has changed all that.
>>
>> Cat 5 and 6 say for the last 15 years, has been just fine as far as
>>contact issues go.

>You obviously never had to run an IT department. Connector problems
>cause 99% of the failures. And a network often had quite a few
>connectors between the switch and the device. In most cases one cable
>from the switch to the patch panel and then one cable from the outlet
>to the PC. That is 4 RJ45 connectors between the switch and a PC!

Yeah, sorta. I don't run an IT department. I do run a consulting biz
that in the past has wired various buildings, offices and homes for
ethernet. I've also helped setup server farms for an ISP. Lots of
connectors involved. I've seen failures, but they were never due to
contact failure. It was almost always failure of the insulation
displacement connection on the jack, crimping failure on the plug,
wrong plug type, and shredded cables. Most customers insist on having
the wiring tested with a cable certifier to detect split pairs and
other wiring screwups that don't show up on continuity tests. All my
crimpers are ratcheting type, which is required for a decent
connection. Lots of other precautions, such as pull tests. After
installation, the wiring is again tested using diagnostics built into
the managed switch.

When I inherit a new system, I run the certifier though the wiring and
usually find problems. Usually, it's bad patch cables with miserable
crimps to the plugs. Lately, I'm finding really awful RJ45 plugs that
really can't be properly crimped. I sometimes find stranded wire RJ45
plugs used with stranded CAT5. That won't work (although the reverse
will work).

I rarely see any "failures" that could be directly attributable to the
connector unless the connector was mechanically damaged. If I had to
assign the blame, it would be with whomever built the patch cable or
installed the wall jacks.

[SoothSayer]

On Thu, 30 Aug 2012 22:30:54 -0700, Jeff Liebermann <je...@cruzio.com>
wrote:

Our gateways have optical links, and 100% redundancy.

IF there were EVER a connection problem on ANY port(for the Enet
discussion), it would switch it out, and alert the operators.

Hp series 8 blades for the C7000 chassis series are cool. The old
blades had vertical locking bar and they moved these down onto the end.
It is amazing how much they pack inside these blades. Dual Zeon, SAS,
Optical interfaces, and Ethernet.

After the third party vendor comes in and wires up our racks (way
cheaper than paying our own people to do it, oddly), we are pretty
confident as they tag each line and run diagnostics on each Ethernet
line. Then our in house QAs verify every element of the build on each
rack.

Our RF guys test out the link side cables and get that set up. Then we
take the whole thing apart and crate the racks and ship them to the
gateway site. There, another person re-assembles them and the same wire
crew (we fly them all over the world) re-runs all the wiring to the rack
destinations. Every cable and every link of any kind gets tested here.
At the site everything works again upon re-assembly. That wiring company
makes more money from us than any other customer they ever had, and their
workers get to see the world like an active duty sailor.

We calibrate our crimpers, and so do the cable wire crews. Hell, their
gear is better than some of our gear as it relates to wires. Bad crimps
are the bane of the industry.

However, a properly constructed system will behave the way I stated.

Bad crimps make certain folks draw improper conclusions, but they are,
in fact, the reason most of the failures they observed occurred. It is
hardly ever a connector contact face, or connector mating contact wire
tangency face.

Back in my early days, I worked on upright video games. We had to
charge the customer (video game operator) a minimum of a 1/2 hour for the
service call. Most of them only took a few minutes. So to keep a
customer from becoming irate that you only spent 3 minutes fixing
something, but charged a half hour, you had to sit behind the machine and
act as if you were fixing something.

Back then card edge fingers and connectors were far more prone to
surface oxidation issues (remember re-seating hard drive connectors on
MFM?). All we had to do to fix the game usually is power down (usually
is already) and remove and re-seat all the main board's edge connectors.
Job done, 95% of the time.

I used to have problem charging a customer for a TV repair for this
reason, back when I did that. That was when I learned that they are
paying for your expertise, not your time. Customers, however, still have
problems accepting that reason, to this day.

Like I said, there are trillions of connections each day that operate
just fine, even in extreme environs.

The failure rate is literally more than an order of magnitude less than
it was 20 years ago.

Connector technology has taken big steps forward too. Smaller and
smaller, yet quite integral. Gold is the reason.

Backplanes and such didn't get added to my numbers. There are 1000s of
trillions of connections of high integrity working every day.

How many do you think were utilized in getting your post to the first
server it hit? Tens of thousands likely.

[Michael A. Terrell]

Jeff Liebermann wrote:
>
> When I inherit a new system, I run the certifier though the wiring and
> usually find problems. Usually, it's bad patch cables with miserable
> crimps to the plugs. Lately, I'm finding really awful RJ45 plugs that
> really can't be properly crimped. I sometimes find stranded wire RJ45
> plugs used with stranded CAT5. That won't work (although the reverse
> will work).

Both leave you 'stranded'? ;-)

[Nico Coesel]

Jeff Liebermann <je...@cruzio.com> wrote:

>On Thu, 30 Aug 2012 22:18:39 GMT, ni...@puntnl.niks (Nico Coesel)
>wrote:
>
>>SoothSayer <SayS...@TheMonastery.org> wrote:
>>
>>>On Wed, 29 Aug 2012 12:58:19 GMT, ni...@puntnl.niks (Nico Coesel) wrote:
>>>
>>>>RJ45 isn't the best connector. In my experience you need to reseat the
>>>>connector after a few years for it to make good contact.
>>>
>>> All the Gold utilized has changed all that.
>>>
>>> Cat 5 and 6 say for the last 15 years, has been just fine as far as
>>>contact issues go.
>
>>You obviously never had to run an IT department. Connector problems
>>cause 99% of the failures. And a network often had quite a few
>>connectors between the switch and the device. In most cases one cable
>>from the switch to the patch panel and then one cable from the outlet
>>to the PC. That is 4 RJ45 connectors between the switch and a PC!
>
>Yeah, sorta. I don't run an IT department. I do run a consulting biz
>that in the past has wired various buildings, offices and homes for
>ethernet. I've also helped setup server farms for an ISP. Lots of
>

>I rarely see any "failures" that could be directly attributable to the
>connector unless the connector was mechanically damaged. If I had to
>assign the blame, it would be with whomever built the patch cable or
>installed the wall jacks.

I agree a lot can go wrong when the wiring is installed. I've seen my
share of badly crimped connectors, poorly installed wall-outlet and
bad punch-down work. But after installation dirt and moisture are the
biggest enemy.

I recently designed a board for which the customer and I decided to
use a spring loaded terminal block instead of RJ45 because it is much
more resistant against poor installation practices and moisture.

[Jeff Liebermann]

On Fri, 31 Aug 2012 03:22:22 -0700, SoothSayer
<SayS...@TheMonastery.org> wrote:

> Our gateways have optical links, and 100% redundancy.

My customers are a bit behind the times. Most are currently upgrading
to gigabit ethernet (1000baseT). Very little fiber except between
servers and switches. Here's a typical horror story. Almost
everything in the boxes are defective due to wrong connectors, badly
installed connectors, or miserable polishing.
<http://802.11junk.com/jeffl/pics/drivel/slides/fiber_01.html>
I originally thought the fiber tester was defective because it was
rejecting almost everything.

> IF there were EVER a connection problem on ANY port(for the Enet
>discussion), it would switch it out, and alert the operators.

Back in the late 1990's, I did some midnight repairs at distant server
farms. Nobody was dumb enough to drive 50-75 miles to reseat a
connector except me. That was before multihoming and failover were
common. I rarely found a defective connection. What I found was were
RJ45 plugs without locking tabs that wiggled out of the jack. Same
with common power cords that had little or no retention force. More
than once, I found that the CAT5 jumper had simply disappeared. I
have seen cases where unplugging the RJ45 and reinserting it solved a
connection problem, but that was due to NWAY negotiation failure, not
an intermittent connector.

>We calibrate our crimpers, and so do the cable wire crews. Hell, their
>gear is better than some of our gear as it relates to wires. Bad crimps
>are the bane of the industry.

The local university and one company has a policy about non-ratcheting
crimpers. If they find anyone using one, the perpetrator gets ejected
or thrown down a flight of stairs, whichever is more appropriate.

>Bad crimps make certain folks draw improper conclusions, but they are,
>in fact, the reason most of the failures they observed occurred. It is
>hardly ever a connector contact face, or connector mating contact wire
>tangency face.

Agreed, to a point. I once made a big mistake and bought a bag of
RJ45 plugs on eBay. Big mistake. Not only was the gold plating
insufficient, the dimensional tolerances were well out of acceptable
specifications. Thanks to the wonders of Chinese technology, we are
now able to successfully produce a genuine intermittent connection at
the connector face instead of just at the insulation displacement
crimp. Some details and horror stories:
<http://www.rj45s.com/Prj45problemareas.html>

> Like I said, there are trillions of connections each day that operate
>just fine, even in extreme environs.

My rough count is that I have about 80 active ethernet ports at my
home. My office probably has twice as many.

> How many do you think were utilized in getting your post to the first
>server it hit? Tens of thousands likely.

Traceroute shows 16 hops, each of which has no less than 8 connectors
involved for a minimum of 128 connectors. (It's actually more like 50
connectors per hop). However, most of the higher speed connectors are
now fiber, not RJ45.

[Phil Hobbs]

Selective coatings like that can really make things hot. They're
sometimes used on thermal solar collectors, or see Dumas' "The Man In
The Iron Mask" for a historical example. (Mildy oxidized metal is black
in the visible but shiny in the IR, so it gets pretty warm in bright
sunlight.)

Cheers

Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

[Phil Hobbs]

No worries, just saw off a couple of cylinders on the Corolla. There'll
be lots of room in the engine compartment, and it'll still be faster
than the 2CV. ;)

[Michael A. Terrell]

Phil Hobbs wrote:

>
> Joerg wrote:
> >
> > This was all so easy on my old Citroen 2CV. You could reach just
> > about anything directly.
> >
>
> No worries, just saw off a couple of cylinders on the Corolla.
> There'll be lots of room in the engine compartment, and it'll
> still be faster than the 2CV. ;)

Take the engine out & replace it with a big rubber band and it'll

[Joerg]

Hey, my 2CV could blaze along the autobahns at 55mph. 60-65mph only with
a stiff tailwind. But ... 50mpg, and that's with an engine designed in
the late 30's.

[josephkk]

On Tue, 28 Aug 2012 17:57:17 -0700, Joerg <inv...@invalid.invalid> wrote:

>Folks,
>
>Have to send 12V/500mA across a connection. So far there is only an
>RJ45. Looking at datasheets I saw current ratings of 1.2A and 1.5A which
>sounds like a lot.
>
>Is this kosher? I know PoE sends up to 600mA across but I've always felt
>uneasy about it when they went up from the (older?) 350mA.

Just in case you are really interested, the connector is IEC 60603-7-x
where x is a speed grade. Straight from my copy of ANSI/TIA-568 C
revision part 2.

The IEC spec is 220 US$ if i read the website correctly:

http://webstore.iec.ch/Webstore/webstore.nsf/ArtNum_PK/41668!opendocument&preview=1

[legg]

On Thu, 30 Aug 2012 22:14:03 GMT, ni...@puntnl.niks (Nico Coesel)
wrote:

Different optically clear components (as in commercial RJ45) also have
different absorption characteristics. But this besides the point, as
is the automobile comparison.

"The unit will sit in full sun occasionally and can become as hot as
the inside of a car under that condition."

For a start, very few people have any idea what the varying
temperatures are in the different areas of their car. They are aware
of how hot their seats are, maybe the passenger compartment air, and
the dashboard, where their favourite CD just got toasted. This usually
involves the IR transmissivity of auto glass and the absorptive
capacity of the upholstery or temperature indexes of toasted articles.

Electronic packages that are designed to sit in full insolation need
to be packaged appropriately, just as connectors (original topic) need
to be selected appropriately for their application.

RL

[Chieftain of the Carpet Crawlers]

nico, the total fucking retard wrote:
>>
>>Interestingly the color we see doesn't matter. Paint can have totally
>>different properties at different wavelengths. There is black paint
>>which is 'white' if you look at it with an infrared camera.

One of the most retarded comments about IR and IR imagery and "black
paint" I have ever seen.

[Chieftain of the Carpet Crawlers]

On Sat, 01 Sep 2012 08:34:45 -0500, legg <le...@nospam.magma.ca> wrote:

>"The unit will sit in full sun occasionally and can become as hot as
>the inside of a car under that condition."

Put a braided sheath over it. Sheesh.

[Warren]

On 12-08-30 4:19 PM, Joerg wrote:
> legg wrote:
>> On Thu, 30 Aug 2012 09:48:41 -0700, Joerg <inv...@invalid.invalid>

>> wrote:
>>
>>> legg wrote:
>>>> On Wed, 29 Aug 2012 09:33:58 -0700, Joerg <inv...@invalid.invalid>
>>>> wrote:
>>>>
>>>>> Nico Coesel wrote:
>>>>>> Joerg <inv...@invalid.invalid> wrote:

..

>>>>> The unit will sit in full sun occasionally and can become as hot as the
>>>>> inside of a car under that condition.

>>>> This could simply mean that a change in colour or surface finish of
>>>> the casing is required. Different colours and materials have different
>>>> albedo qualities.
>>>>
>>>> White is three times better than grey, order of magnitude+ better than
>>>> black.
>>>>
>>> Not sure if the difference is that stark in real life. I own a white car
>>> and a couple of weeks ago during really hot summer days I had a black
>>> Volkswagen rental. I didn't feel that much of a difference when coming
>>> back to the parked car after severak hours.
>>

>> Really. So then you've got nothing to worry about.
>>
>> Solar contribution to thermals ia roughly a kilowatt per square meter
>> in the direct overhead case.
>>
>
> Sure, but there is also re-radiation and reflection. Except maybe for a
> Hell Angels Harley or a low-rider rap mobile, vehicles are normally not
> painted a dull "primer black". It's more metallic-anthracite plus a
> shiny clear coat on top.

My father painted his stock car's radiator silver one time. From that
point on, the engine overheated badly and he could not understand why (I
was not old enough at the time to be of any help).

After several weeks of trying to work out the problem he eventually gave
up and discarded that radiator and put a different "black" one in. The
problem then completely vanished. It wasn't until years later, when I
took thermodynamics in high school, that I realized why a black radiator
works better for dissipating heat.

But what I don't understand is why air conditioning heat exchangers are
all aluminum in color. Why do you not see black A/C heat exchanger
coils? Even on your car, your radiator will be black, but the A/C heat
exchanger in front of it (which also must dissipate heat) is left an
aluminum (no paint) color.

Would the A/C heat exchanger work better if it were also painted a thin
layer of black paint? I've never had the guts to try it on my home's
central air coils. :)

Warren.

[rickman]

On 9/8/2012 7:50 PM, Warren wrote:
> On 12-08-30 4:19 PM, Joerg wrote:
>> legg wrote:
>>> On Thu, 30 Aug 2012 09:48:41 -0700, Joerg <inv...@invalid.invalid>
>>> wrote:
>>>
>>>> legg wrote:
>>>>> On Wed, 29 Aug 2012 09:33:58 -0700, Joerg <inv...@invalid.invalid>
>>>>> wrote:
>>>>>
>>>>>> Nico Coesel wrote:
>>>>>>> Joerg <inv...@invalid.invalid> wrote:

> ...

The radiator should not have worked differently because it was silver
other than the fact that it was painted and so the spaces between the
fins were smaller and the air flow more restricted. Radiators, contrary
to their name, don't really do much radiating heat. The heat is
conducted to the air flowing over them. That is why they have the thin
fins with lots of surface area. If they really radiated the heat, they
would just plain be large, likely covering the entire surface of the car.

That explains why the aluminum heat exchanger works just fine, color
doesn't matter when you are conducting the heat away.

Rick

[Joerg]

I also suspect that the silver paint Warren's dad used was the usual
thick and "soupy" type metallic paint. That stuff could add an
insulation layer where you really didn't want one.

In my youthful days in the 80's I used that kind of paint for my
electronics projects. It looked cool (well, for the 80's it did) and it
was so popular that you could always find leftovers or small can on sale.

[Jasen Betts]

On 2012-09-08, Warren <ve3...@gmail.com> wrote:
> On 12-08-30 4:19 PM, Joerg wrote:

> My father painted his stock car's radiator silver one time. From that
> point on, the engine overheated badly and he could not understand why (I
> was not old enough at the time to be of any help).
>
> After several weeks of trying to work out the problem he eventually gave
> up and discarded that radiator and put a different "black" one in. The
> problem then completely vanished. It wasn't until years later, when I
> took thermodynamics in high school, that I realized why a black radiator
> works better for dissipating heat.

mainly it was the paint insulating the fins from the air. the black
lacquer used on old radiators was to stop them from oxidising,

> But what I don't understand is why air conditioning heat exchangers are
> all aluminum in color. Why do you not see black A/C heat exchanger
> coils?

because copper is too expesive,

> Even on your car,

I once has a car with an unpainted aluminium rdiator core, this was
stock, not a modification.

> Would the A/C heat exchanger work better if it were also painted a thin
> layer of black paint? I've never had the guts to try it on my home's
> central air coils. :)

if it was really thin, like black anodize, maybe
.



--
⚂⚃ 100% natural

--- Posted via news://freenews.netfront.net/ - Complaints to ne...@netfront.net ---

[Warren]

I suppose you're right.

>> That explains why the aluminum heat exchanger works just fine, color
>> doesn't matter when you are conducting the heat away.
>>
>
> I also suspect that the silver paint Warren's dad used was the usual
> thick and "soupy" type metallic paint. That stuff could add an
> insulation layer where you really didn't want one.

It could be- it may have been thicker than it should have been (I
couldn't tell you now what kind of paint it was).

Copper of course would need some kind of coating to keep the thing
from corroding, whereas I suppose the aluminum is prolly not so
prone, depending upon the alloy used.

Warren.