Today's Message Index:
----------------------
1. 12:36 AM - Re: Re: Are home grown temperature probes feasable? (rparigor@suffolk.lib.ny.us)
2. 10:06 AM - Re: Z-12 SD-20 wire size / fusible link size (Robert L. Nuckolls, III)
3. 03:20 PM - Re: Basic Electricity....Grrrrr......... (XeVision)
4. 05:23 PM - Re: Are home grown temperature probes feasable? (rampil)
5. 06:03 PM - S701 Contactor Failure Analysis (Robert L. Nuckolls, III)
6. 06:20 PM - Re: S701 Contactor Failure Analysis (Robert L. Nuckolls, III)
7. 06:48 PM - Re: S701 Contactor Failure Analysis (Ron Quillin)
8. 07:13 PM - Re: S701 Contactor Failure Analysis (Bret Smith)
9. 08:13 PM - Re: S701 Contactor Failure Analysis (Richard E. Tasker)
10. 08:22 PM - Re: S701 Contactor Failure Analysis (Bill Watson)
11. 09:33 PM - Re: S701 Contactor Failure Analysis (Robert L. Nuckolls, III)
12. 09:36 PM - Re: S701 Contactor Failure Analysis (Robert L. Nuckolls, III)
Message 1
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Subject: | Re: Are home grown temperature probes feasable? |
Hi Ira
Thx for the info on your 15 probes. Curious, you mention you
have 4 CHT ring probes that I think are the type that get sandwiched
between spark plug and cylinder head. Why did you go that route as
compared to purchasing two extra CHT probes from Rotax which would allow
reading all 4 cylinders? Perhaps it gives you a more desirable reading?
Or??
Thx.
Ron Parigoris
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Subject: | Re: Z-12 SD-20 wire size / fusible link size |
At 12:44 AM 2/17/2010, you wrote:
>
>Bob,
>
>(Rev 12A) Z-12 suggests using a 10 gauge wire for the B-lead from
>the SD-20 with a 16 gauge fusible link. I believe you recommend
>sizing fusible links with wire that is 4 sizes smaller than the wire
>being protected. I'm guessing the B-lead wire size was changed
>during a cut-&-paste from 12 gauge to 10 gauge without re-sizing the
>fusible link? Do you recommend 10 gauge wire for an SD-20 B-lead and
>if so do you recommend 14 gauge wire for a fusible link if a fusible
>link is used to protect the B-lead?
16AWG would be fine . . . so would 14AWG . . . it just
needs to serve the function of "electrically weak link"
while not overheating beyond that which the insulation
will stand . . .
16AWG isn't even close to getting too hot at 20A. See:
http://aeroelectric.com/Pictures/Wire/22AWG_20A.pdf
I'm working on tooling to build a base for the minature
ANL style current limiters. We'll be offering these
"robust fuses" on the website in the not too distant
future. That "4AWG downsize" rule is a minimum step
size, it COULD be 6 or even 8AWG smaller in some
cases.
For a 20A alternator, 12AWG b-lead with a 16AWG
fusible link would be centered on contemporary
design goals.
Bob . . .
Message 3
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Subject: | Re: Basic Electricity....Grrrrr......... |
We encounter an even more basic issue on occasion regarding 12 or 24Volts availability
at the ballast.
Once in a while, we get the call "I have 12 volts at the ballast input connector
but the light does not come on when I hook power to it". My response is typically,
try measuring the voltage at that location with a load on it. Either our
system, a light bulb (incandescent) or other load.
Do you still have about 12V or 24V with the load or does the voltage plummet as
soon as a load is applied. If so, look for corroded connections in the wiring,
a bad switch, a bad ground, etc.
Sometimes they are using the airframe for ground (not our preference) and sometimes
the airframe at that location is not well grounded back to the neg bus/ neg
bat terminal.
People building airplanes, if they do any of the electrical work, should learn
some basics of how electrical circuits work. When they don't understand these
basics they automatically blame the non operational component(s).
--------
LED still has a long way to go to compete with HID as a landing light. This is
true in terms of total lumens and reach (distance).
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=286865#286865
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Subject: | Re: Are home grown temperature probes feasable? |
nope, the reason was BMA compatibility
--------
Ira N224XS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=286870#286870
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Subject: | S701 Contactor Failure Analysis |
Last year, Marty Emrath told us about the failure of a new
contactor he had purchased from B&C. B&C replaced the contactor
but Marty was justifiably curious as to root cause of the
failure.
I offered to document a tear-down analysis and Marty sent
me the carcass. I was looking for something fun to do this
afternoon so I took the dead puppy apart.
The pictures at . . .
http://www.aeroelectric.com/Pictures/Contactors/S701_Failure_Teardown/
Are pretty much self explanatory. One thing is for certain.
This product is much more sophisticated than its ancestors
that first took to the air in a C-140.
The last picture tells the tale . . .
http://www.aeroelectric.com/Pictures/Contactors/S701_Failure_Teardown/TearDown_10.jpg
Seems the assembler wasn't really awake yet when this
device went across their work station. One coil wire
was poorly soldered to its terminal . . . the other had
no solder at all.
Thanks for sharing your experience with us Martin!
Bob . . .
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Subject: | Re: S701 Contactor Failure Analysis |
>
>The last picture tells the tale . . .
>
>http://www.aeroelectric.com/Pictures/Contactors/S701_Failure_Teardown/TearDown_10.jpg
>
>Seems the assembler wasn't really awake yet when this
>device went across their work station. One coil wire
>was poorly soldered to its terminal . . . the other had
>no solder at all.
Already had a comment on the analysis . . . someone noted that
the terminals around which the coil wires are wrapped are square
and may indeed have sharp corners.
He reminded me of an arcane point-to-point wiring process
for complex digital circuits called "wire wrap". This
process used special wire, tools, sharp edged square terminal
posts and no solder. The tools were designed to tightly
wrap the wire around the post with enough turns, and
stretching force to create multiple gas-tight joints
on the corners at each connection.
As I recall this technology called for about 6 tightly
spaced turns around the post (24+ points of contact).
Since this coil-form is plastic . . . and soldering these
joints would call for considerable heat and time,
it may well be that the original design calls for
no solder at all.
In this case, the assembler of the failed item was
perhaps not in possession of the right tool. The turns
about both posts are not those produced by a "wire wrap"
tool. The curious thing is that there is SOME solder
on one of the terminals . . . perhaps didn't pass a
continuity test and the solder dab "fixed it" only to
have the other joint fail later.
Guess we'll have to tear down another contactor to
see. I don't think I have one in the shop. I'll go
buy one.
Bob . . .
Message 7
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Subject: | Re: S701 Contactor Failure Analysis |
You have a good recollection.
I just did some wire-wrap late last year.
However, the wire used has Kynar or other insulation that is removed
to expose a bare, generally tin coated, conductor.
The wire used to wind the coil, from your pictures, appears to be
'magnet' wire which has an insulating coating. The wire-wrap
process, as I have always seen it implemented, is not designed for
this type of insulated wire and is not expected to breech the
insulation to form a contact.
I believe your original diagnosis of no solder was spot-on.
Ron Q.
At 18:18 2/17/2010, you wrote:
>He reminded me of an arcane point-to-point wiring process
> for complex digital circuits called "wire wrap". This
> process used special wire, tools, sharp edged square terminal
> posts and no solder. The tools were designed to tightly
> wrap the wire around the post with enough turns, and
> stretching force to create multiple gas-tight joints
> on the corners at each connection.
>
> As I recall this technology called for about 6 tightly
> spaced turns around the post (24+ points of contact).
> Since this coil-form is plastic . . . and soldering these
> joints would call for considerable heat and time,
> it may well be that the original design calls for
> no solder at all.
Message 8
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Subject: | S701 Contactor Failure Analysis |
Thank you Bob, It is always interesting to learn more about the art of
aircraft electronics.
Bret Smith
RV-9A N16BL
Blue Ridge, GA
www.FlightInnovations.com
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Wednesday, February 17, 2010 9:18 PM
Subject: Re: AeroElectric-List: S701 Contactor Failure Analysis
<nuckolls.bob@aeroelectric.com>
>
>The last picture tells the tale . . .
>
>http://www.aeroelectric.com/Pictures/Contactors/S701_Failure_Teardown/TearD
own_10.jpg
>
>Seems the assembler wasn't really awake yet when this
>device went across their work station. One coil wire
>was poorly soldered to its terminal . . . the other had
>no solder at all.
Already had a comment on the analysis . . . someone noted that
the terminals around which the coil wires are wrapped are square
and may indeed have sharp corners.
He reminded me of an arcane point-to-point wiring process
for complex digital circuits called "wire wrap". This
process used special wire, tools, sharp edged square terminal
posts and no solder. The tools were designed to tightly
wrap the wire around the post with enough turns, and
stretching force to create multiple gas-tight joints
on the corners at each connection.
As I recall this technology called for about 6 tightly
spaced turns around the post (24+ points of contact).
Since this coil-form is plastic . . . and soldering these
joints would call for considerable heat and time,
it may well be that the original design calls for
no solder at all.
In this case, the assembler of the failed item was
perhaps not in possession of the right tool. The turns
about both posts are not those produced by a "wire wrap"
tool. The curious thing is that there is SOME solder
on one of the terminals . . . perhaps didn't pass a
continuity test and the solder dab "fixed it" only to
have the other joint fail later.
Guess we'll have to tear down another contactor to
see. I don't think I have one in the shop. I'll go
buy one.
Bob . . .
Message 9
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Subject: | Re: S701 Contactor Failure Analysis |
Your recollection is generally true and the same as the wire I have used
for all the wire wrapping I have done. However, once upon a time there
was wire sold for wrapping that did not require stripping.
Unfortunately, I don't remember who sold it nor do I have any. Further,
I seem to recall that it was not too successful as it eventually tended
to short anywhere it overlapped under tension.
The wire on the teardown certainly looks like common magnet wire. And
in any case, three or four turns would certainly not be sufficient to
make long term reliable contact in something like this which is likely
to be exposed to rather harsh environmental conditions. I agree with
Bob that they just forgot to solder the wires - the operator probably
got interrupted during assembly.
Dick Tasker
Ron Quillin wrote:
> You have a good recollection.
>
> I just did some wire-wrap late last year.
> However, the wire used has Kynar or other insulation that is removed
> to expose a bare, generally tin coated, conductor.
>
> The wire used to wind the coil, from your pictures, appears to be
> 'magnet' wire which has an insulating coating. The wire-wrap process,
> as I have always seen it implemented, is not designed for this type of
> insulated wire and is not expected to breech the insulation to form a
> contact.
>
> I believe your original diagnosis of no solder was spot-on.
>
> Ron Q.
>
> At 18:18 2/17/2010, you wrote:
>> He reminded me of an arcane point-to-point wiring process
>> for complex digital circuits called "wire wrap". This
>> process used special wire, tools, sharp edged square terminal
>> posts and no solder. The tools were designed to tightly
>> wrap the wire around the post with enough turns, and
>> stretching force to create multiple gas-tight joints
>> on the corners at each connection.
>>
>> As I recall this technology called for about 6 tightly
>> spaced turns around the post (24+ points of contact).
>> Since this coil-form is plastic . . . and soldering these
>> joints would call for considerable heat and time,
>> it may well be that the original design calls for
>> no solder at all.
> *
>
>
> *
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Message 10
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Subject: | Re: S701 Contactor Failure Analysis |
I'm feeling old... My only hands-on experimental circuit making was pre-dig
ital. =C2- Over the years I'd pickup electronics mags and see references
to "wire wrapped" terminals and never had a clue what it referred to. =C2
-Now I get it... Thanks.
Bill
-- Sent from my Palm Pre
Ron Quillin wrote:
You have a good recollection.
I just did some wire-wrap late last year.
However, the wire used has Kynar or other insulation that is removed to
expose a bare, generally tin coated, conductor.
The wire used to wind the coil, from your pictures, appears to be
'magnet' wire which has an insulating coating.=C2- The wire-wrap
process, as I have always seen it implemented, is not designed for this
type of insulated wire and is not expected to breech the insulation to
form a contact.
I believe your original diagnosis of no solder was spot-on.
Ron Q.
At 18:18 2/17/2010, you wrote:
He reminded me of an arcane
point-to-point wiring process
=C2- for complex digital circuits called "wire wrap".
This
=C2- process used special wire, tools, sharp edged square terminal
=C2- posts and no solder. The tools were designed to tightly
=C2- wrap the wire around the post with enough turns, and
=C2- stretching force to create multiple gas-tight joints
=C2- on the corners at each connection.
=C2- As I recall this technology called for about 6 tightly
=C2- spaced turns around the post (24+ points of contact).
=C2- Since this coil-form is plastic . . . and soldering these
=C2- joints would call for considerable heat and time,
=C2- it may well be that the original design calls for
=C2- no solder at all.
Message 11
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Subject: | Re: S701 Contactor Failure Analysis |
At 10:22 PM 2/17/2010, you wrote:
>I'm feeling old... My only hands-on experimental
>circuit making was pre-digital. Over the
>years I'd pickup electronics mags and see
>references to "wire wrapped" terminals and never
>had a clue what it referred to. Now I get it... Thanks.
>
>Bill
see:
http://en.wikipedia.org/wiki/Wire_wrap
This is the modern incarnation used on complex backplanes
where gazillion-layer boards are impractical. The no-strip
version is from way-back-when and it didn't hang around
long.
Bob . . .
Message 12
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Subject: | Re: S701 Contactor Failure Analysis |
>The wire on the teardown certainly looks like common magnet
>wire. And in any case, three or four turns would certainly not be
>sufficient to make long term reliable contact in something like this
>which is likely to be exposed to rather harsh environmental
>conditions. I agree with Bob that they just forgot to solder the
>wires - the operator probably got interrupted during assembly.
Just for grins, I took a chunk of the wire off the
failed coil and subjected it to a puddle of molten
solder. The insulation was indeed a "solder-eze"
type . . . you can solder through it without pre-
stripping.
The plastic used on the bobbin did melt at soldering
iron temperatures but not quickly. So it seems a rational
deduction that the failed joints were intended to be
soldered. The right temperature and flux combination
would have produced a reliable joint with minimal
effect on the bobbin.
I guess I won't go buy one to take apart . . . perhaps
we'll get another carcass to inspect for other reasons
one day.
Bob . . .
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