Engine Management Units

[legg]

On Fri, 18 Mar 2016 08:51:16 -0000 (UTC), Cursitor Doom
<curd@notformail.com> wrote:

On Fri, 18 Mar 2016 00:07:03 -0500, legg wrote:

Early technet response suggests chemical contamination in vias, but
would require SEM EDX to confirm. This contamination could difuse in the
conformal coating cure stress lines (ie the pucker).

Can you post a url for this site? I searched but got about a million
microsoft support links instead.

"SEM EDX"? Is that something to do with electron microscopy? I have an
admittedly huge collection of test gear here, but not a single electron
microscope.

I don't see vias involved in every instance - some sites seem to develop
at pure surface mount pad sites.

True, but they're in the minority. Maybe that's relevant; maybe not. The
we don't have a large enough sample here to say.


There's an image of copper dendrites on Steve Zeva's gallery

http://stevezeva.homestead.com/

http://stevezeva.homestead.com/Dendrite_1.jpg

These tend to be inter-node rather than centrally expanding.

Yes, still no precise matches.


A close examination of tin whiskers should reveal a characteristic three
dimensional spike/thread detail. Not likely here.


Yes, TW seem to come out at right angles to the plain; these are surface
creepers.

Technet link was previously posted.

http://listserv.ipc.org/scripts/wa.exe?A1=ind1603&L=TechNet

Question is, what is your repair plan?

You don't seem to have any indication of the unit's present state
other than sticking it back in the car and seeing if the car starts.
No fb on xtal replacement yet.......

The blemishes you're chasing may have nothing to do with actual fault.

The spatter pattern is also suggestive of the impact from an external
source, such as a flicked paint brush.

The single metalic entrapment pictured should also flick off with a
knife blade. But without some before and after passive probing, you'll
never know if this did anything.

RL

 

[Cursitor Doom]

On Fri, 18 Mar 2016 14:05:57 -0500, Jon Elson wrote:

If these things are on TOP of the coating, then it should be easier to
make a conductivity measurement. (But, yes, I see you say they are
brittle.)

Indeed they are - very! Anyone who can come up with a method for
establishing if they're conductive and if so, to what extent deserves a
Nobel Prize, I reckon.

 

[Mike Tomlinson]

En el artículo <37cc548b-c211-4846-a1df-54c46f865865@googlegroups.com>,
pfjw@aol.com <pfjw@aol.com> escribió:

why do the British drink
warm beer?

So we can actually taste it. Have you drunk warm American beer? It's
icy cold to hide the fact that it tastes bloody awful. QED.



--
(\_/)
(='.'=) Bunny says: Windows 10? Nein danke!
(")_(")

 

[Jon Elson]

Cursitor Doom wrote:

They seem to emerge from under it and spread along the surface, but I
can't confirm that yet as I've resisted disturbing them so far in case
they disintegrate and defy further analysis.

Right, basically what I said above is correct. There seems to have been
some sort of breakdown of the clear coating which has enabled these
things to get a foothold. They then break out and traverse along the
board *on top* of the coating. So it's doubtful they could cause any
short circuits unless by sheer chance the tip of one of them hits another
spot of coating that's broken down above a trace

Hmmm, very interesting. If they have GROWN out of the board, especially
from the vias, then they have a really good chance of being conductive.
And, maybe the ones across the TOP of the coating are no problem, but if
there are some on the back side or under the coating, they could cause
trouble. If the conformal coat has broken down, moisture and various
contaminants could have gotten under it and started making conductive paths.
If the controller depends on some high impedance circuitry, that could cause
it to quit.

If these things are on TOP of the coating, then it should be easier to make
a conductivity measurement. (But, yes, I see you say they are brittle.)

Jon

 

[Cursitor Doom]

On Sat, 19 Mar 2016 00:26:58 +0100, Sjouke Burry wrote:

Going for the nobelprice then.
Apply a very small drop of salt water to the tip of one of those out
grows then one side of your ohmmeter to a ground and the other side
gently touching the drop of water.
If the whisker conducts, that should show up.

Thank you for that, Sjouke. I'll ponder this idea of yours as I can see
some merit in it. the only problem AISI is these fibres are so tiny it's
going to require a steady hand and a good eye - but I have neither!
However, it's very late here now so I'll report back tomorrow with the
results - *if* I can pull it off.

 

[Sjouke Burry]

On 18.03.16 21:57, Cursitor Doom wrote:

On Fri, 18 Mar 2016 14:05:57 -0500, Jon Elson wrote:

If these things are on TOP of the coating, then it should be easier to
make a conductivity measurement. (But, yes, I see you say they are
brittle.)

Indeed they are - very! Anyone who can come up with a method for
establishing if they're conductive and if so, to what extent deserves a
Nobel Prize, I reckon.

Going for the nobelprice then.
Apply a very small drop of salt water to the tip of
one of those out grows then one side of your ohmmeter
to a ground and the other side gently touching the
drop of water.
If the whisker conducts, that should show up.

 

[Mike Tomlinson]

En el artículo <nchih2$j56$1@dont-email.me>, Gunther Heiko Hagen
<guntherxxx@quantserve.de> escribió:

The best beers in the world - proper beers - are brewed by
the Belgians, the Czechs and the very best of all of course - the Germans.

Yep. I was thrilled when I went in a little off-the-beaten-track bar in
a remote part of the Canary islands to find they had three chiller
cabinets stuffed with craft Belgian and German beers.

Have my tickets booked for Oktoberfest

--
(\_/)
(='.'=) Bunny says: Windows 10? Nein danke!
(")_(")

 

[Cursitor Doom]

On Sat, 19 Mar 2016 21:15:10 +0100, Sjouke Burry wrote:

Eye sight is what made me buy a "jewelers headband loop",
feed that to google pictures to see one.

Yeah, I've got one with a little light in the centre; very useful! Still
got rotten motor skills, though.

 

[amdx]

On 3/17/2016 8:01 AM, MJC wrote:

In article <nce05k$n7j$2@dont-email.me>, curd@notformail.com says...

Nowadays
all enamel copper seems to be clear, but back in the day the enamel was a
sort of deep plum shade - which is what I see here. I'll do some searches
for pictures of TW and see if some match what I see on this board....

I didn't know modern enamel had gone clear. Sounds like a recipe for
confusion! Even if all enamel is now also the sort that turns into flux
if you try to solder the wire...

Mike.

Far as I've seen, the latest change (20 yrs) was to a higher
temperature enamel that is Brown. The change was made for electric
motors because with VFD's they can run at higher temperatures.
Mikek

 

[Sjouke Burry]

On 19.03.16 2:12, Cursitor Doom wrote:

On Sat, 19 Mar 2016 00:26:58 +0100, Sjouke Burry wrote:

Going for the nobelprice then.
Apply a very small drop of salt water to the tip of one of those out
grows then one side of your ohmmeter to a ground and the other side
gently touching the drop of water.
If the whisker conducts, that should show up.

Thank you for that, Sjouke. I'll ponder this idea of yours as I can see
some merit in it. the only problem AISI is these fibres are so tiny it's
going to require a steady hand and a good eye - but I have neither!
However, it's very late here now so I'll report back tomorrow with the
results - *if* I can pull it off.

Eye sight is what made me buy a "jewelers headband loop",
feed that to google pictures to see one.

 

[MJC]

In article <56edb461$0$4110$e4fe514c@textnews.kpn.nl>,
burrynulnulfour@ppllaanneett.nnll says...

Eye sight is what made me buy a "jewelers headband loop",
feed that to google pictures to see one.

Probably better to spell it "loup" if you want to do a search (though no
doubt Google will suggest that)...

Mike.

 

[Cursitor Doom]

On Sun, 20 Mar 2016 09:43:10 -0500, legg wrote:

On Fri, 18 Mar 2016 20:57:34 -0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

On Fri, 18 Mar 2016 14:05:57 -0500, Jon Elson wrote:

If these things are on TOP of the coating, then it should be easier to
make a conductivity measurement. (But, yes, I see you say they are
brittle.)

Indeed they are - very! Anyone who can come up with a method for
establishing if they're conductive and if so, to what extent deserves a
Nobel Prize, I reckon.

If they are water soluble, you might just clean the whole unit in your
dishwasher.

Depends on whether the aim is repair, or donation to science. If the
latter - ship to mfr in sealed bag with note attached - expect no
response.

RL

I won't be sending it back to the makers; like you say they're an
ungrateful bunch.
I'd like to power the board up and check for signs of life - see if that
xtal's working and so forth. But in view of those growths it seems
pointless unless I can get the back off and inspect the reverse side for
further signs of it spreading. But I don't want to risk damaging it in
the process. I'm not very good with practical things like that. They
invariably take FAR longer than I expect at the outset - and then I get
threatened with divorce.

 

[legg]

On Fri, 18 Mar 2016 20:57:34 -0000 (UTC), Cursitor Doom
<curd@notformail.com> wrote:

On Fri, 18 Mar 2016 14:05:57 -0500, Jon Elson wrote:

If these things are on TOP of the coating, then it should be easier to
make a conductivity measurement. (But, yes, I see you say they are
brittle.)

Indeed they are - very! Anyone who can come up with a method for
establishing if they're conductive and if so, to what extent deserves a
Nobel Prize, I reckon.

If they are water soluble, you might just clean the whole unit in your
dishwasher.

Depends on whether the aim is repair, or donation to science. If the
latter - ship to mfr in sealed bag with note attached - expect no
response.

RL

 

[legg]

On Fri, 18 Mar 2016 10:37:46 -0500, legg <legg@nospam.magma.ca> wrote:

<snip>

The blemishes you're chasing may have nothing to do with actual fault.

The spatter pattern is also suggestive of the impact from an external
source, such as a flicked paint brush.

Also, it brings to mind patterns produced by spatter from a
contaminated air hose jet.

RL

 

[Michael A. Terrell]

Gunther Heiko Hagen wrote:

On Fri, 18 Mar 2016 18:13:46 +0000, Mike Tomlinson wrote:

En el artĂ­culo <37cc548b-c211-4846-a1df-54c46f865865@googlegroups.com>,
pfjw@aol.com <pfjw@aol.com> escribiĂł:

why do the British drink warm beer?

So we can actually taste it. Have you drunk warm American beer? It's
icy cold to hide the fact that it tastes bloody awful. QED.



They don't appear to use hops for flavouring in N. America

Then explain why Florida has started farming hops instead of oranges,
in many places.

 

[Gunther Heiko Hagen]

On Tue, 29 Mar 2016 11:27:28 -0400, Michael A. Terrell wrote:

Then explain why Florida has started farming hops instead of oranges,
in many places.

For export, of course.

 

[Phil Allison]

Heiko Hagen wrote:

They don't appear to use hops for flavouring in N. America and Australia,

** America produces 28,000 tonnes of hops per year - practically all of it going into beer. Only Germany produces more, with 34,000 tonnes.

https://en.wikipedia.org/wiki/Hops#Cultivation_and_harvest

Thing is, they probably don't use enough of it in each barrel to suit you.

Small and craft brewers generally use a lot more malt and hops per barrel than the big commercial ones.



..... Phil

 

[Michael A. Terrell]

Gunther Heiko Hagen wrote:

On Tue, 29 Mar 2016 11:27:28 -0400, Michael A. Terrell wrote:

Then explain why Florida has started farming hops instead of oranges,
in many places.

For export, of course.

Wrong! They are being sold to micro breweries in the United States.