Today's Message Index:
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1. 04:00 AM - Re: Ducati R/R deficiencies (David Josephson)
2. 05:20 AM - Attachment limits? (Robert L. Nuckolls, III)
3. 08:19 AM - Re: Attachment limits? (Ken Ryan)
4. 11:43 AM - Re: Attachment limits? (Eric Page)
5. 04:51 PM - Re: Ducatti R/R deficiencies (MMiller)
Message 1
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Subject: | Re: Ducati R/R deficiencies |
On Sep 6, 2016, at 2:04 PM, Bob Nuckolls wrote:
>
> I took some time to finish an article I started some
> years ago explaining my perceptions of thermal management
> deficiencies in the Ducatti R/R supplied with Rotax
> engines.
>
> http://tinyurl.com/zvkoh4p
Indeed, and thanks. I have disassembled a couple of these and found the same problems.
There seem to be two heat-related failure modes: (a) the semiconductors
get too hot for the thermal resistance between junction and free air, and (b)
the solder joints are poor between the leads of the devices and the pc board,
and between the pc board and the connector, leading to localized heating. In
two of the cases I have, the solder had melted often enough that the board was
charred, and the component leads were not well cleaned so the solder had dirt
and oxidation in it. They are no doubt caught up in European lead-free solder
requirements too.
To be fair these are inexpensive regulators designed for motorcycles where they
are often installed in free air -- at the top of the firewall where they are
usually found in airplanes is not a particularly cool place for them. Charging
a motorcycle battery, plus a headlight, and ignition, is something they can handle
well. Rotax can't design/build everything, it would be even more expensive
than it is if they did (ever priced a wastegate controller for a 914?) and
with proper cooling and low current drain the Ducati r/r is not too bad. Once
it starts to fail due to heat however it's downhill from there.
The Silent Hektik device seems to be a good replacement although I have not used
one -- they will not ship to the US and seem not too interested in the light
aviation market anymore.
I have designed a more robust version using low Vf diodes and scrs and will probably
have some test hours on one by the end of the year. The basic design is
OK, I agree with Bob that it just needs better thermal management.
Message 2
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Subject: | Attachment limits? |
Matt,
Recently I've received 'bounced' e-mails for
postings to the AeroElectric List that cited
an exceedance of limits on attachment size.
Is this something new? To what size should attachments/
embedded images be limited?
Thanks!
Bob . . .
Message 3
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Subject: | Re: Attachment limits? |
Matt, I have had the same problem, with my attachments being well under the
published maximums.
On Tue, Sep 6, 2016 at 5:26 PM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> Matt,
>
> Recently I've received 'bounced' e-mails for
> postings to the AeroElectric List that cited
> an exceedance of limits on attachment size.
>
> Is this something new? To what size should attachments/
> embedded images be limited?
>
> Thanks!
>
>
> Bob . . .
>
Message 4
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Subject: | Re: Attachment limits? |
I'll add one more data point. On a few of these occasions I recall members c
ommenting on this problem, but I had received their initial post via the ema
il echo system, with the allegedly oversize attachments intact. So, it seem
s that in some cases the server is accepting attachments but nonetheless sen
ding bounce messages.
Eric
> On Sep 7, 2016, at 8:15 AM, Ken Ryan <keninalaska@gmail.com> wrote:
> Matt, I have had the same problem, with my attachments being well under th
e published maximums.
>
>
>> On Tue, Sep 6, 2016 at 5:26 PM, Robert L. Nuckolls, III <nuckolls.bob@aer
oelectric.com> wrote:
>> Matt,
>>
>> Recently I've received 'bounced' e-mails for postings to the AeroElectric
List that cited an exceedance of limits on attachment size.
>>
>> Is this something new? To what size should attachments/embedded images be
limited?
>>
>> Thanks!
>> Bob . . .
Message 5
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Subject: | Re: Ducatti R/R deficiencies |
Bob,
You have a few misconceptions about the Rotax regulator. All the power components
are screwed to the case, heatsink compound is used. Rotax does not depend on
the potting compound for heatsinking the power components. In your photo, item
1 and 2 are SCRs (MCR16N). Item 3 is a MOSFET to drive the fault lamp. The
power diodes (button case) are not shown, they would attach between the plate
on the left side and the two leads on the lower left side of the PCB. This
version is obsolete since late 2009.
I posted these links back in July, I guess you missed my post and conclusions.
The older pre 2010 regulator
Here a is a PDF schematic/assy for this version
https://drive.google.com/open?id=0ByPxADyU-DwPdTQ3NWp5LW9iOHc
Typical failure mode PDF
https://drive.google.com/open?id=0ByPxADyU-DwPTnlXcUVEQTdfcVU
Current production since 2010.
Here is a PDF schematic/assy for this version
https://drive.google.com/open?id=0ByPxADyU-DwPWTBBcGlUeENTcHc
Here are some failure PDF photos
https://drive.google.com/open?id=0ByPxADyU-DwPYm1rYUVsbUJyQ3M
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=460344#460344
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