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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
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 Posted: Fri May 30, 2014 2:26 pm Post subject: Info on MGL Enigma |
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While trying to fathom why the CHT readings on the MGL Enigma EFIS had stopped on my friend's Rotax 912 powered JA Highlander I delved into the manual for the EFIS and its RDAC unit (the box that all senders report to before their data is passed along to the EFIS). On page 6 or so of the RDAC manual there is a picture of the back of the Enigma with a note that the battery under a rectangular cover should be changed every two years. Upon removing said cover I discovered a CR2032 lithium battery. I checked its voltage output and found it to be 2.9 volts. A new one that the aircraft owner just happened to have in his tool kit (he maintains medical equipment for a living) put out 3.3 volts so we replaced the old one.
More investigation into the setup menus for EFIS revealed that there is an option for a Rotax sender for the CHT setup and when we checked the unit we found it had reset to a J type thermocouple. Resetting it to the Rotax sender solved the problem and the EFIS began reporting good CHT values.
Curious to find out if the low output of the CR2032 was responsible for the glitch in the CHT setup I delved into the manual for the EFIS and could find no reference to it in the manual's table of contents, index, or during a long skim of its contents. The same was true of the RADC manual with the exception of the picture and note mentioned earlier.
Now we find that the same thing has happened to the oil pressure reading. Again the setup has been changed to reflect a different type of sender, only this time restoring it to the Rotax sender option has not fixed it. There are two sender options for each of resistive type senders and voltage type. On either resistive option (the Rotax option is a resistive sender) the bar graph on the EFIS locks up and does not read. When I set it to either of the voltage type it then reads but it reads backward, i.e. as the engine revs up the reading drops and vice versa.
The oil pressure sender is a VDO unit and I have located it in VDO's technical offerings online. VDO recommends that the sender be installed dry with no teflon tape or thread sealant so that it will ground properly so we have an investigative path when we return to the airplane this weekend.
MGL has taken the Enigma technical info off line and the aircraft's owner has not been able to find any information on the CR2032 battery as to what it does or how to change it properly.Â
Does anyone out there know about it?
Thanks,
Rick Girard
It isn't necessary to have relatives in Kansas City in order to be unhappy.
 - Groucho Marx
[quote][b]
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ceengland7(at)gmail.com
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| Posted: Fri May 30, 2014 3:20 pm Post subject: Info on MGL Enigma |
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On 5/30/2014 5:25 PM, Richard Girard wrote:
| Quote: | While trying to fathom why the CHT readings on the MGL Enigma EFIS had stopped on my friend's Rotax 912 powered JA Highlander I delved into the manual for the EFIS and its RDAC unit (the box that all senders report to before their data is passed along to the EFIS). On page 6 or so of the RDAC manual there is a picture of the back of the Enigma with a note that the battery under a rectangular cover should be changed every two years. Upon removing said cover I discovered a CR2032 lithium battery. I checked its voltage output and found it to be 2.9 volts. A new one that the aircraft owner just happened to have in his tool kit (he maintains medical equipment for a living) put out 3.3 volts so we replaced the old one.
More investigation into the setup menus for EFIS revealed that there is an option for a Rotax sender for the CHT setup and when we checked the unit we found it had reset to a J type thermocouple. Resetting it to the Rotax sender solved the problem and the EFIS began reporting good CHT values.
Curious to find out if the low output of the CR2032 was responsible for the glitch in the CHT setup I delved into the manual for the EFIS and could find no reference to it in the manual's table of contents, index, or during a long skim of its contents. The same was true of the RADC manual with the exception of the picture and note mentioned earlier.
Now we find that the same thing has happened to the oil pressure reading. Again the setup has been changed to reflect a different type of sender, only this time restoring it to the Rotax sender option has not fixed it. There are two sender options for each of resistive type senders and voltage type. On either resistive option (the Rotax option is a resistive sender) the bar graph on the EFIS locks up and does not read. When I set it to either of the voltage type it then reads but it reads backward, i.e. as the engine revs up the reading drops and vice versa.
The oil pressure sender is a VDO unit and I have located it in VDO's technical offerings online. VDO recommends that the sender be installed dry with no teflon tape or thread sealant so that it will ground properly so we have an investigative path when we return to the airplane this weekend.
MGL has taken the Enigma technical info off line and the aircraft's owner has not been able to find any information on the CR2032 battery as to what it does or how to change it properly.Â
Does anyone out there know about it?
Thanks,
Rick Girard
It isn't necessary to have relatives in Kansas City in order to be unhappy.
 - Groucho Marx
|
I can't help with specific info on the MGL, but using that battery for 'backup' is fairly common in electronics. If you use a desktop PC, odds are good that there's one on the motherboard. My old Garmin III Pilot gps has one in it. (Note that they make that case style in both a lithium 'primary' battery, and a lithium rechargeable battery, & it's sometimes difficult to tell which the mfgr is using.) In the applications I've seen, the battery keeps a CMOS memory alive, and that's where basic configuration settings are stored in a lot of devices. If the battery goes too low to keep the CMOS memory active, the device will forget whatever settings were stored there. I would think that more current tech, especially in an a/c device, would avoid using CMOS memory & the required battery, but some really high dollar avionics still use it.
On many PC's, if the battery dies, after battery replacement you sometimes have to do a 'hard reset' by shorting a pair of pins on the motherboard to completely clear the CMOS memory before re-entering all the parameters needed.
Sounds like it's time for a Skype call to S Africa. 
Charlie
[quote][b]
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jay(at)horriblehyde.com
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| Posted: Sat May 31, 2014 7:37 am Post subject: Info on MGL Enigma |
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I have forwarded this to my colleague, who happens to own MGL J. I call him on Monday to follow up.
Jay
From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Richard Girard
Sent: 31 May 2014 12:26 AM
To: aeroelectric-list(at)matronics.com
Subject: Info on MGL Enigma
While trying to fathom why the CHT readings on the MGL Enigma EFIS had stopped on my friend's Rotax 912 powered JA Highlander I delved into the manual for the EFIS and its RDAC unit (the box that all senders report to before their data is passed along to the EFIS).
On page 6 or so of the RDAC manual there is a picture of the back of the Enigma with a note that the battery under a rectangular cover should be changed every two years. Upon removing said cover I discovered a CR2032 lithium battery. I checked its voltage output and found it to be 2.9 volts. A new one that the aircraft owner just happened to have in his tool kit (he maintains medical equipment for a living) put out 3.3 volts so we replaced the old one.
More investigation into the setup menus for EFIS revealed that there is an option for a Rotax sender for the CHT setup and when we checked the unit we found it had reset to a J type thermocouple. Resetting it to the Rotax sender solved the problem and the EFIS began reporting good CHT values.
Curious to find out if the low output of the CR2032 was responsible for the glitch in the CHT setup I delved into the manual for the EFIS and could find no reference to it in the manual's table of contents, index, or during a long skim of its contents. The same was true of the RADC manual with the exception of the picture and note mentioned earlier.
Now we find that the same thing has happened to the oil pressure reading. Again the setup has been changed to reflect a different type of sender, only this time restoring it to the Rotax sender option has not fixed it. There are two sender options for each of resistive type senders and voltage type. On either resistive option (the Rotax option is a resistive sender) the bar graph on the EFIS locks up and does not read. When I set it to either of the voltage type it then reads but it reads backward, i.e. as the engine revs up the reading drops and vice versa.
The oil pressure sender is a VDO unit and I have located it in VDO's technical offerings online. VDO recommends that the sender be installed dry with no teflon tape or thread sealant so that it will ground properly so we have an investigative path when we return to the airplane this weekend.
MGL has taken the Enigma technical info off line and the aircraft's owner has not been able to find any information on the CR2032 battery as to what it does or how to change it properly.
Does anyone out there know about it?
Thanks,
Rick Girard
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
| Quote: | | [/b][/b][/b][b]http://www.matronics.com/Navigator?AeroElectric-List[b] |
0123456789
[quote][b]
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jay(at)horriblehyde.com
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| Posted: Mon Jun 02, 2014 1:03 am Post subject: Info on MGL Enigma |
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Here is the reply from Rainier, the owner and founder of MGL:
The CR2032 battery is only used to maintain items that change frequently like calculated fuel levels, local pressure settings etc.
Setup is stored in a flash memory section of a secondary processor chip in the EFIS. This does not need a backup battery.
If setup data stored here is not maintained there is usually only one
cause: The supply voltage to that processor is raised briefly (micro-seconds to mill-seconds) above about 8V. This can happen if the supply to the EFIS contains sharp voltage spikes (typically caused by bad regulators or high voltage ignition is coupling into ground or supply). This can also happen if there are static discharges typically caused by airflow over metal parts that are not grounded.
Eventually, this will damage the flash memory which is the part that dies first in our experience.
When this happens we replace the processor chip. If you have a techie handy - it is a type ATMEL ATMega128. It is a SMD package but easy to solder/desolder if you have the experience. Once replaced I would also recommend replacing the 16Mhz crystal right next to this chip - it tends to wear out over a long time (we replace these as a matter of course when we get an Enigma in for repairs). No specific programming of the new processor needs to be done as the firmware will detect a new processor and do the programming and setup of this chip automatically (the first start-up will take a bit longer and you will see some messages on the display to this effect).
Rainier
--
MGL Avionics
Postal:
Postnet Suite X15
Somerset West 7129
South Africa
Physical:
5 Fuchsia street
Somerset West 7130
South Africa
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
HH Enterprises - Aircraft assembly, repair, wiring and avionics
- Flight instruction
- General and Electrical Engineering services
(NHD Elec Eng, BTech Elec Eng, GDE ELec Eng)- Great dinner parties and conversation
- General adventuring, climbing, kayaking and living
Blog: www.rawhyde.wordpress.com
Cel: 083 300 8675
Email: jay(at)horriblehyde.com (jay(at)horriblehyde.com)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Charlie England
Sent: 31 May 2014 01:20 AM
To: aeroelectric-list(at)matronics.com
Subject: Re: Info on MGL Enigma
On 5/30/2014 5:25 PM, Richard Girard wrote:
| Quote: |
While trying to fathom why the CHT readings on the MGL Enigma EFIS had stopped on my friend's Rotax 912 powered JA Highlander I delved into the manual for the EFIS and its RDAC unit (the box that all senders report to before their data is passed along to the EFIS).
On page 6 or so of the RDAC manual there is a picture of the back of the Enigma with a note that the battery under a rectangular cover should be changed every two years. Upon removing said cover I discovered a CR2032 lithium battery. I checked its voltage output and found it to be 2.9 volts. A new one that the aircraft owner just happened to have in his tool kit (he maintains medical equipment for a living) put out 3.3 volts so we replaced the old one.
More investigation into the setup menus for EFIS revealed that there is an option for a Rotax sender for the CHT setup and when we checked the unit we found it had reset to a J type thermocouple. Resetting it to the Rotax sender solved the problem and the EFIS began reporting good CHT values.
Curious to find out if the low output of the CR2032 was responsible for the glitch in the CHT setup I delved into the manual for the EFIS and could find no reference to it in the manual's table of contents, index, or during a long skim of its contents. The same was true of the RADC manual with the exception of the picture and note mentioned earlier.
Now we find that the same thing has happened to the oil pressure reading. Again the setup has been changed to reflect a different type of sender, only this time restoring it to the Rotax sender option has not fixed it. There are two sender options for each of resistive type senders and voltage type. On either resistive option (the Rotax option is a resistive sender) the bar graph on the EFIS locks up and does not read. When I set it to either of the voltage type it then reads but it reads backward, i.e. as the engine revs up the reading drops and vice versa.
The oil pressure sender is a VDO unit and I have located it in VDO's technical offerings online. VDO recommends that the sender be installed dry with no teflon tape or thread sealant so that it will ground properly so we have an investigative path when we return to the airplane this weekend.
MGL has taken the Enigma technical info off line and the aircraft's owner has not been able to find any information on the CR2032 battery as to what it does or how to change it properly.
Does anyone out there know about it?
Thanks,
Rick Girard
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
|
I can't help with specific info on the MGL, but using that battery for 'backup' is fairly common in electronics. If you use a desktop PC, odds are good that there's one on the motherboard. My old Garmin III Pilot gps has one in it. (Note that they make that case style in both a lithium 'primary' battery, and a lithium rechargeable battery, & it's sometimes difficult to tell which the mfgr is using.) In the applications I've seen, the battery keeps a CMOS memory alive, and that's where basic configuration settings are stored in a lot of devices. If the battery goes too low to keep the CMOS memory active, the device will forget whatever settings were stored there. I would think that more current tech, especially in an a/c device, would avoid using CMOS memory & the required battery, but some really high dollar avionics still use it.
On many PC's, if the battery dies, after battery replacement you sometimes have to do a 'hard reset' by shorting a pair of pins on the motherboard to completely clear the CMOS memory before re-entering all the parameters needed.
Sounds like it's time for a Skype call to S Africa.
Charlie | Quote: | | [/b][/b][/b][/b][/b]http://www.matronics.com/Navigator?AeroElectric-List[/b][/b][/b] |
0123456
[quote][b]
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Mon Jun 02, 2014 5:45 am Post subject: Info on MGL Enigma |
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At 04:02 AM 6/2/2014, you wrote:
Here is the reply from Rainier, the owner and founder of MGL:
The CR2032 battery is only used to maintain items
that change frequently like calculated fuel
levels, local pressure settings etc.
Setup is stored in a flash memory section of a
secondary processor chip in the EFIS. This does not need a backup battery.
If setup data stored here is not maintained there is usually only one
cause: The supply voltage to that processor is
raised briefly (micro-seconds to mill-seconds)
above about 8V. This can happen if the supply to
the EFIS contains sharp voltage spikes (typically
caused by bad regulators or high voltage ignition
is coupling into ground or supply). This can
also happen if there are static discharges
typically caused by airflow over metal parts that are not grounded.
Eventually, this will damage the flash memory
which is the part that dies first in our experience.
When this happens we replace the processor chip.
If you have a techie handy - it is a type ATMEL
ATMega128. It is a SMD package but easy to
solder/desolder if you have the experience. Once
replaced I would also recommend replacing the
16Mhz crystal right next to this chip - it tends
to wear out over a long time (we replace these as
a matter of course when we get an Enigma in for
repairs). No specific programming of the new
processor needs to be done as the firmware will
detect a new processor and do the programming and
setup of this chip automatically (the first
start-up will take a bit longer and you will see
some messages on the display to this effect).
I am exceedingly skeptical of these assertions.
I don't know of a single 5v regulator offered to
the task of conditioning power for electronics
that doesn't handily mitigate any of the commonly
known variables on the ship's bus. DO-160 offers
a clear and concise path to living confidently
in the world of DC powered vehicles.
Crystals that 'wear out'?
Static discharges ? ! ? ! . . . again, for any
piece of hardware to be qualified for installation
on a TC aircraft, it has to be capable of withstanding
discharges of a 150pF capacitor through 330 ohm
resistor fed directly to every input/output pin
on the device under test. TEN times for positive
spikes, TEN more times for negative spikes.
Sound brutal . . . but the components and architecture
for designing to this level of stress is rudimentary
and has been as common to the designer's toolbox as
a hammer is to a carpenter's toolbox. I quit doing
the test 25 years ago after learning what it took
to pass . . . easily . . . every time.
If the stresses cited are genuine risks to MGL's
products, then they've failed to understand
and embrace the real world stresses found in
mobile DC powered system of all stripe . . . not
the least of which are airplanes.
Bob . . .
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Mon Jun 02, 2014 6:45 am Post subject: Info on MGL Enigma |
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At 04:02 AM 6/2/2014, you wrote:
Here is the reply from Rainier, the owner and founder of MGL:
The CR2032 battery is only used to maintain items that change frequently like calculated fuel levels, local pressure settings etc.
Setup is stored in a flash memory section of a secondary processor chip in the EFIS. This does not need a backup battery.
If setup data stored here is not maintained there is usually only one
cause: The supply voltage to that processor is raised briefly (micro-seconds to mill-seconds) above about 8V. This can happen if the supply to the EFIS contains sharp voltage spikes (typically caused by bad regulators or high voltage ignition is coupling into ground or supply). This can also happen if there are static discharges typically caused by airflow over metal parts that are not grounded.
Eventually, this will damage the flash memory which is the part that dies first in our experience.
When this happens we replace the processor chip. If you have a techie handy - it is a type ATMEL ATMega128. It is a SMD package but easy to solder/desolder if you have the experience. Once replaced I would also recommend replacing the 16Mhz crystal right next to this chip - it tends to wear out over a long time (we replace these as a matter of course when we get an Enigma in for repairs). No specific programming of the new processor needs to be done as the firmware will detect a new processor and do the programming and setup of this chip automatically (the first start-up will take a bit longer and you will see some messages on the display to this effect).
I am exceedingly skeptical of these assertions.
I don't know of a single 5v regulator offered to
the task of conditioning power for electronics
that doesn't handily mitigate any of the commonly
known variables on the ship's bus. DO-160 offers
a clear and concise path to living confidently
in the world of DC powered vehicles.
Crystals that 'wear out'?
Static discharges ? ! ? ! . . . again, for any
piece of hardware to be qualified for installation
on a TC aircraft, it has to be capable of withstanding
15KV discharges of a 150pF capacitor through 330 ohm
resistor fed directly to every input/output pin
on the device under test. TEN times for positive
spikes, TEN more times for negative spikes.
Sound brutal . . . but the components and architecture
for designing to this level of stress is rudimentary
and has been as common to the designer's toolbox as
a hammer is to a carpenter's toolbox. I quit doing
the test 25 years ago after learning what it took
to pass . . . easily . . . every time.
If the stresses cited are genuine risks to MGL's
products, then they've failed to understand
and embrace the real world stresses found in
mobile DC powered system of all stripe . . . not
the least of which are airplanes.
Bob . . . [quote][b]
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jay(at)horriblehyde.com
Guest
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| Posted: Mon Jun 02, 2014 11:39 pm Post subject: Info on MGL Enigma |
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Hello again listers,
Here is a further response from Rainier:
I did not say that spikes or similar ARE the cause of what it going on.
It might be something completely unrelated. It's a pretty complex system.
There are no old style linear regulators in the system.
There are three high frequency switch mode supplies and all input power is
protected by a heavy duty transorb apart from other filtering (mostly
inductive/capacitive).
Nevertheless, we are talking about a system that has multiple connectivity
to other electrical systems on the aircraft - anything going on anywhere and
the EFIS gets it. We are taking about transient events at RF frequencies.
Do-160 simply does not cater for this on a long term bases. But that is
another story.
So, honestly, without actually having the system on a bench and
investigating - and conclusively finding the cause, going on like that is
not called for here.
Getting back to the Flash memory - yes it does fail if it gets transient
power events that make it through the system by whatever path. It may take
years. However that is by no means the only possible cause. Flash is known
to wear over time. Manufacturers of these devices guarantee 10 years of data
retention typically, even if no writes take place - yet these devices are
used throughout the industry for missions where it is assumed that they will
never fail. Usually they don't.
In this case we don't even know if this memory has failed. It might be
something else - perhaps the communications link between main CPU and the
processor that contains this memory has gone faulty. It could be anything.
I'm guessing. That is all I can do without having the Enigma on my bench.
Electronics do fail - does not matter how much money you spend on the
components. Service history of the Enigma has been excellent. The number of
Enigmas coming back to the factory for repairs is almost nil. That is not
too surprising - it has been designed for open cockpit ultralights and it is
quite tough. But they are getting older now and failures of electronic
components become more of a factor. There is something called a "bathtub
failure curve" - because it looks like it. Failures tend to occur when the
device is new (partly the reason we run them for 48 hours at elevated
temperatures during manufacture) - then things settle down and after some
time failure rates start creeping up slowly as things age.
Components that do age are crystals (They are mechanical devices - high
frequency types in particular have a higher failure rate in our experience).
Then we have ceramic capacitors - a typical EFIS has hundreds of them. Some
start leaking after a while. Most of the time that is not an issue but
sometimes it is. We don't use tantalums because of reliability concerns
(good caps but they have an annoying tendency to blow up). Our electrolytics
are top quality devices - can't even remember any failures. Then we get to
the semiconductors. Well, here we have a pretty random failure pattern. They
do die for no apparent reason. The rate is low but it does happen. Yes, we
use aerospace, automotive and industrial spec devices - we do not use
consumer graded devices at all.
Most failures are perhaps related to PCB failures (usually thermal stress
cracking vias). Some of our PCBs are high tech multi-layer. They are more
sensitive - part of the process. Some assemblies are lead free and the
entire industry has been battling for years with "tin-wiskers".
Microscopic growths of tin between tracks and pads. Only visible under a
microscope. Takes years to cause a problem. That we have had. Lucky this is
not so much of an issue anymore as lead free processes and fluxes have
improved and I have yet to see such an issue on anything produced in the
last 4 or 5 years. "Cold solder joints" - that happens either via repeated
thermal stress cracking a solder joint or a manufacturing defect that may
take years to manifest itself. Yes, it happens. It passes all tests and
optical quality controls (we use an automated AOI machine plus visual checks
at various stages during the assembly
process) - yet it still manages to avoid early detection. Sure, the rate is
low but we make thousands of devices every month. Including devices not
intended for aircraft (and not under our brand name). I would love a zero
failure rate. Failures are bad. Everybody gets annoyed - from the customer
to us. We can't have a zero failure rate - that is a pipe dream. But we can
always work to reduce it to the barest minimum. If we did not do that we'd
be out of business long ago.
Most of our repairs are directly related to what we call "blow ups".
Reverse polarity issues, connecting power or grounds to the wrong places
etc. Interface driver chips (RS232, CAN, switches etc) blown for various
reasons - the items directly connected to the outside World.
All of that happens typically during installation. Mostly with the so called
"professional installers, AMOs etc". I'm not kidding. We find the home
builders are the ones with the least issues - perhaps because most take the
time to study the docs and plan their wiring. There is no rush, no
deadlines. That helps.
Our statistics (which we do keep for obvious reasons) shows this trend very
clearly.
Instruments get dropped, might have a hard time during transport - sometimes
they get soaked in water or oil.
Anyway, I can't really comment on this Enigma until I see it myself (if that
ever happens). If there is a problem, whatever the cause may be - we can fix
it. That is the bottom line.
Rainier
--
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Eric M. Jones
Joined: 10 Jan 2006
Posts: 565
Location: Massachusetts
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| Posted: Tue Jun 03, 2014 5:40 am Post subject: Re: Battery Was MGL Enigma |
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It is hard to say that a 3V battery measuring 2.9V is dead or not depending on load. The nominal discharge current of the battery is 0.2 mA. Putting a 150k in parallel will show 2.9V or above for a still good battery. But since getting there is half the work, change it.
http://www.adafruit.com/datasheets/maxell_cr2032_datasheet.pdf
See DX.com (Deal Extreme) for a 10 pack of Sony 3V CR2032 Lithium Ion
$5.98. Free shipping
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Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Tue Jun 03, 2014 11:00 am Post subject: Info on MGL Enigma |
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At 02:37 AM 6/3/2014, you wrote:
--> AeroElectric-List message posted by: "Jay Hyde" <jay(at)horriblehyde.com>
Hello again listers,
Here is a further response from Rainier:
I did not say that spikes or similar ARE the cause of what it going on.
It might be something completely unrelated. It's a pretty complex system.
. . . then why even mention it? The customer
does not benefit from a narration of possible
causes . . . especially when those causes include
things that 'might' be wrong with his airplane.
But to assert that stresses external to the
product's enclosure can zap a micro-controller
does nothing to engender confidence in the rest of
hardware under the best of circumstances.
There are no old style linear regulators in the system.
There are three high frequency switch mode supplies and all input power is
protected by a heavy duty transorb apart from other filtering (mostly
inductive/capacitive).
<SNIP>
Electronics do fail - does not matter how much money you spend on the
components. Service history of the Enigma has been excellent. The number of
Enigmas coming back to the factory for repairs is almost nil.
When we conduct a reliability study on an assembly,
powers-that-be don't really start smiling until
your aggregate MTBF drops below 1 x 10 minus 7
failures per flight hour. For critical systems
1 x 10 minus 9 is the target.
So if your device has 100 components in it, INDIVIDUAL
failure rates have to be 100x better than the aggregate.
If this guy has crystals that warrant routine replacement
base on some fielded experience . . . he is well
advised to change brands.
<snip>
intended for aircraft (and not under our brand name). I would love a zero
failure rate. Failures are bad. Everybody gets annoyed - from the customer
to us. We can't have a zero failure rate - that is a pipe dream. But we can
always work to reduce it to the barest minimum. If we did not do that we'd
be out of business long ago.
Most of our repairs are directly related to what we call "blow ups".
Reverse polarity issues, connecting power or grounds to the wrong places
etc. Interface driver chips (RS232, CAN, switches etc) blown for various
reasons - the items directly connected to the outside World.
One cannot necessarily design every i/o port
to withstand the vagaries of neophyte installations
but failures of components not connected directly
to the outside world is cause for concern.
All of that happens typically during installation. Mostly with the so called
"professional installers, AMOs etc". I'm not kidding. We find the home
builders are the ones with the least issues - perhaps because most take the
time to study the docs and plan their wiring. There is no rush, no
deadlines. That helps.
Our statistics (which we do keep for obvious reasons) shows this trend very
clearly.
Instruments get dropped, might have a hard time during transport - sometimes
they get soaked in water or oil.
Anyway, I can't really comment on this Enigma until I see it myself (if that
ever happens). If there is a problem, whatever the cause may be - we can fix
it. That is the bottom line.
To be sure, nobody can offer "zero failure rates" but
they can be exceedingly small. Builders anticipating operations
over long stretches of unfriendly terrain or in IMC would be well
advised to craft 'plan-b', 'plan-c' or whatever in the
event the whole system goes belly-up. "Barest minimum"
failure rates are un-quantified.
If we had any hardware coming back from the field
suffering some of the failures cited above . . .
things around here would, shall we say, get
very 'tense'?
A display with this kind of data . ..
[img]cid:.0[/img]
implies certain capabilities. Capabilities that
require TC aircraft designers to go Level A
software/hardware, careful partitioning of
functions and probably dual screens.
Do your own Failure Modes Effects Analysis
based on how you need to use this hardware.
Have a solid alternative for every situation
when it isn't working.
Bob . . .
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