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Magnetized Dynon D100 Display

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cskelt

Joined: 11 May 2021
Posts: 7
Location: Houston, TX

Posted: Fri May 14, 2021 7:32 am Post subject: Magnetized Dynon D100 Display

Here's a really weird one that occurred recently. Flying on a North-Easterly heading the PAI-700 panel mount compass informed me I was heading West. This is a new problem and the photo taken some years ago shows the relative positions of the instruments with reasonable agreement between the panel mount compass and the Dynon EFIS.



Taxiing around a circle without the Dynon EFIS D100 in the panel gives good compass readings. With the EFIS in place the compass reading remains between South and West. I took the compass and EFIS to the compass manufacturer, Precision Aviation, where they confirmed that the compass is OK and the EFIS magnetization too strong for a mu-metal shield to help.



The next photo below shows a compass correctly pointing North and the second shows it after rotating to point to the EFIS display, folded out from the box of electronics and sensors. The magnetization appears to be concentrated halfway up the left side of the display.



Dynon Technical Support deny there is anything wrong and my eventual request to buy a replacement display went unanswered. This led to a google search for a demagnetizer that found many plausible devices for up to a few hundred dollars that's no doubt less than a new display. Can anyone advise if it's feasible to demagnetize a display screen and offer any tips, or ideas as to how the display became magnetized?



I understand that a standalone magnetic compass isn't required if you have an remote electronic magnetometer but I appreciate the redundancy and the units did after all coexist harmoniously for some years.



Thanks in advance!!

Chris Skelt



LNC2 N1990L at KIWS.

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_________________
Chris Skelt
Lancair 320 N1990L at KIWS

finn.usa(at)gmail.com
Guest

Posted: Fri May 14, 2021 9:10 am Post subject: Magnetized Dynon D100 Display

This is indeed very odd. The D-100 case is made of alum, I think. 

Anything inside could possibly be a power-supply coil, but that should 

not be a permanent magnet. Long shot -- try to remove the battery pack.



How old is the D-100? Still under warranty?



I would be tempted to carefully use a simple demagnetizer. Radio Shack 

used to sell them for something like $20. Tapehead demagnetizer.



Finn



On 5/14/2021 11:32 AM, cskelt wrote:

 	  Quote: 	
		   



 Here's a really weird one that occurred recently. Flying on a North-Easterly heading the PAI-700 panel mount compass informed me I was heading West. This is a new problem and the photo taken some years ago shows the relative positions of the instruments with reasonable agreement between the panel mount compass and the Dynon EFIS.



 Taxiing around a circle without the Dynon EFIS D100 in the panel gives good compass readings. With the EFIS in place the compass reading remains between South and West. I took the compass and EFIS to the compass manufacturer, Precision Aviation, where they confirmed that the compass is OK and the EFIS magnetization too strong for a mu-metal shield to help.



 The next photo below shows a compass correctly pointing North and the second shows it after rotating to point to the EFIS display, folded out from the box of electronics and sensors. The magnetization appears to be concentrated halfway up the left side of the display.



 Dynon Technical Support deny there is anything wrong and my eventual request to buy a replacement display went unanswered. This led to a google search for a demagnetizer that found many plausible devices for up to a few hundred dollars that's no doubt less than a new display. Can anyone advise if it's feasible to demagnetize a display screen and offer any tips, or ideas as to how the display became magnetized?



 I understand that a standalone magnetic compass isn't required if you have an remote electronic magnetometer but I appreciate the redundancy and the units did after all coexist harmoniously for some years.



 Thanks in advance!!

 Chris Skelt



 LNC2 N1990L at KIWS.



 --------

 Chris Skelt

 Lancair 320 N1990L at KIWS





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=501927#501927





 Attachments:



 http://forums.matronics.com//files/d100_magnetized_798.jpg


	




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Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Fri May 14, 2021 12:23 pm Post subject: Magnetized Dynon D100 Display

Best thing would be to email Dynon support. They are very good.



On 5/14/2021 10:09 AM, Finn Lassen wrote:

 	  Quote: 	
		   

 

 This is indeed very odd. The D-100 case is made of alum, I think. 

 Anything inside could possibly be a power-supply coil, but that should 

 not be a permanent magnet. Long shot -- try to remove the battery pack.

 

 How old is the D-100? Still under warranty?

 

 I would be tempted to carefully use a simple demagnetizer. Radio Shack 

 used to sell them for something like $20. Tapehead demagnetizer.

 

 Finn

 

 On 5/14/2021 11:32 AM, cskelt wrote:

> 

>

> Here's a really weird one that occurred recently. Flying on a 

> North-Easterly heading the PAI-700 panel mount compass informed me I 

> was heading West. This is a new problem and the photo taken some years 

> ago shows the relative positions of the instruments with reasonable 

> agreement between the panel mount compass and the Dynon EFIS.

>

> Taxiing around a circle without the Dynon EFIS D100 in the panel gives 

> good compass readings. With the EFIS in place the compass reading 

> remains between South and West. I took the compass and EFIS to the 

> compass manufacturer, Precision Aviation, where they confirmed that 

> the compass is OK and the EFIS magnetization too strong for a mu-metal 

> shield to help.

>

> The next photo below shows a compass correctly pointing North and the 

> second shows it after rotating to point to the EFIS display, folded 

> out from the box of electronics and sensors. The magnetization appears 

> to be concentrated halfway up the left side of the display.

>

> Dynon Technical Support deny there is anything wrong and my eventual 

> request to buy a replacement display went unanswered. This led to a 

> google search for a demagnetizer that found many plausible devices for 

> up to a few hundred dollars that's no doubt less than a new display. 

> Can anyone advise if it's feasible to demagnetize a display screen and 

> offer any tips, or ideas as to how the display became magnetized?

>

> I understand that a standalone magnetic compass isn't required if you 

> have an remote electronic magnetometer but I appreciate the redundancy 

> and the units did after all coexist harmoniously for some years.

>

> Thanks in advance!!

> Chris Skelt

>

> LNC2 N1990L at KIWS.

>

> --------

> Chris Skelt

> Lancair 320 N1990L at KIWS

>

>

> Read this topic online here:

>

> http://forums.matronics.com/viewtopic.php?p=501927#501927

>

>

> Attachments:

>

> http://forums.matronics.com//files/d100_magnetized_798.jpg

 

 

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_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

nuckolls.bob(at)aeroelect
Guest

Posted: Fri May 14, 2021 12:35 pm Post subject: Magnetized Dynon D100 Display

 	  Quote: 	
		  

 Dynon Technical Support deny there is anything wrong and my eventual request to buy a replacement display went unanswered. This led to a google search for a demagnetizer that found many plausible devices for up to a few hundred dollars that's no doubt less than a new display. Can anyone advise if it's feasible to demagnetize a display screen and offer any tips, or ideas as to how the display became magnetized?



 I understand that a standalone magnetic compass isn't required if you have an remote electronic magnetometer but I appreciate the redundancy and the units did after all coexist harmoniously for some years.



 Thanks in advance!!

 Chris Skelt

 	


   Chris, this is a real puzzler! I'm sorry that

   Dynon hasn't shown more interest in resolving

   the issue.



   I've dropped a note to John Torode at

   Dynon (the head cheese). Let's see if he

   is willing to be of assistance.



 

 

   Bob . . .



   Un impeachable logic: George Carlin asked, "If black boxes

   survive crashes, why don't they make the whole airplane

   out of that stuff?"

cskelt

Joined: 11 May 2021
Posts: 7
Location: Houston, TX

Posted: Fri May 14, 2021 1:46 pm Post subject: Re: Magnetized Dynon D100 Display

Thanks to all for the quick replies.  It's not the battery -- I removed it and checked.  Nor is it the aluminum carcass that I also removed before partially disconnecting the display and folding it down so the face rests on the bench. The photo shows the compass pointing at the display with the back side up.



I'm as certain as I can be that the magnetism is "something" at the edge of the screen.  The Dynon unit is over ten years old and had 300 hours of faultless performance behind it before this happened.  



I've had excellent service up until now from Dynon--several issues with the EMS were dealt with promptly and effectively.  And the 360 degree taxi test with and without the EFIS in place was suggested by one of the Dynon guys on the stand at Sun-n-Fun.

_________________
Chris Skelt
Lancair 320 N1990L at KIWS

nuckolls.bob(at)aeroelect
Guest

Posted: Fri May 14, 2021 3:18 pm Post subject: Magnetized Dynon D100 Display

 	  Quote: 	
		  

 I've had excellent service up until now from Dynon--several issues with the EMS were dealt with promptly and effectively.  And the 360 degree taxi test with and without the EFIS in place was suggested by one of the Dynon guys on the stand at Sun-n-Fun. 	


   You've hit them with a ringer . . . I'm not

   surprised at the reaction of the troops in

   the trenches . . . but it's all just physics

   and the answer will be simple.



   Let's see if John T can help out . . .



 

   Bob . . .



   Un impeachable logic: George Carlin asked, "If black boxes

   survive crashes, why don't they make the whole airplane

   out of that stuff?"

DougW

Joined: 16 Sep 2015
Posts: 14
Location: Washington

Posted: Fri May 14, 2021 5:02 pm Post subject: Magnetized Dynon D100 Display

Chris,



Just a thought here - have you tried to place the D100 near other compass

indicators to verify that the D100 is indeed magnetized?  (The compass on

your iPhone (if that is what you have) is apparently not affected by a

nearby magnet!).  Did you move it around and rotate it to see if the

apparent magnetism is localized at some point in the D100?  Is it possible

that you had a steel screw or nut to secure the unit in place?  What would

happen if you removed both units from the panel and positioned them in

various arrangements in magnetically benign area?



Just thinking out loud!



Doug Windhorn



--

finn.usa(at)gmail.com
Guest

Posted: Sat May 15, 2021 8:12 pm Post subject: Magnetized Dynon D100 Display

Didn't see the pictures before.



Is that a steel rod holding the display in place?



Anything steel or iron, if removable do so.



Then simply demagnetize it.



Actually, the D-100 has a remote compass, right?



If so I don't see any reason you couldn't demagnetize the D-100. Others 

here may give good reasons why not.



Finn

On 5/14/2021 5:46 PM, cskelt wrote:

 	  Quote: 	
		   



 Thanks to all for the quick replies.  It's not the battery -- I removed it and checked.  Nor is it the aluminum carcass that I also removed before partially disconnecting the display and folding it down so the face rests on the bench. The photo shows the compass pointing at the display with the back side up.



 I'm as certain as I can be that the magnetism is "something" at the edge of the screen.  The Dynon unit is over ten years old and had 300 hours of faultless performance behind it before this happened.



 I've had excellent service up until now from Dynon--several issues with the EMS were dealt with promptly and effectively.  And the 360 degree taxi test with and without the EFIS in place was suggested by one of the Dynon guys on the stand at Sun-n-Fun.



 --------

 Chris Skelt

 Lancair 320 N1990L at KIWS





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=501940#501940




	




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user9253

Joined: 28 Mar 2008
Posts: 1927
Location: Riley TWP Michigan

Posted: Sun May 16, 2021 1:28 pm Post subject: Re: Magnetized Dynon D100 Display

Today I positioned a hand-held compass near my 10 year old D-180 screen.  

The compass swung 130 degrees as it neared the left side of the screen, just 

like cskelt's.  Luckily my plane has a remote magnetometer, no panel mounted

compass.  The master switch was off during the test.  My instrument panel 

does not have steel parts, just aluminum.

_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Sun May 16, 2021 5:12 pm Post subject: Magnetized Dynon D100 Display

At 04:28 PM 5/16/2021, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com>



 Today I positioned a hand-held compass near my 10 year old D-180 screen.  

 The compass swung 130 degrees as it neared the left side of the screen, just 

 like cskelt's.  Luckily my plane has a remote magnetometer, no panel mounted

 compass.  The master switch was off during the test.  My instrument panel 

 does not have steel parts, just aluminum. 	


   Interesting! Thank you for that. Perhaps John T

   can enlighten us as to the cause.



 

   Bob . . .



   Un impeachable logic: George Carlin asked, "If black boxes

   survive crashes, why don't they make the whole airplane

   out of that stuff?"

cskelt

Joined: 11 May 2021
Posts: 7
Location: Houston, TX

Posted: Mon May 17, 2021 5:49 am Post subject: Re: Magnetized Dynon D100 Display

Thank you Joe Gores as a 10 year old D180 and D100 of similar vintage presumably share a screen type, so this isn't a unique phenomenon.  What Joe's data point can't tell us is whether his magnetism was always present or occurred recently, like mine, after years of non-magnetic functioning.  



In reply to Doug Windhorn's post, I removed the compass and D100 from the panel, opened up the D100, and folded out the display to persuade myself that the magnetism was in the display, not the electronics in the carcass, and to establish that it's permanent magnetism, not RF interference from live avionics.  I used the panel mount compass and a hiking compass.  The (admittedly rather cryptic) photos in the original post were intended to illustrate this.  The threaded steel rod that locks the EFIS into the mounting tray does not appear to be magnetized.



If these devices do indeed spontaneously magnetize, the need is for a demagnetizer, not a replacement screen, as the latter would be a relatively expensive and potentially only temporary fix. 



Chris Skelt

_________________
Chris Skelt
Lancair 320 N1990L at KIWS

cskelt

Joined: 11 May 2021
Posts: 7
Location: Houston, TX

Posted: Mon May 17, 2021 5:52 am Post subject: Re: Magnetized Dynon D100 Display

Thank you Joe Gores as a 10 year old D180 and D100 of similar vintage presumably share a screen type, so this isn't a unique phenomenon.  What Joe's data point can't tell us is whether his magnetism was always present or occurred recently, like mine, after years of non-magnetic functioning.  



In reply to Doug Windhorn's post, I removed the compass and D100 from the panel, opened up the D100, and folded out the display to persuade myself that the magnetism was in the display, not the electronics in the carcass, and to establish that it's permanent magnetism, not RF interference from live avionics.  I used the panel mount compass and a hiking compass.  The (admittedly rather cryptic) photos in the original post were intended to illustrate this.  The threaded steel rod that locks the EFIS into the mounting tray does not appear to be magnetized.



If these devices do indeed spontaneously magnetize, the need is for a demagnetizer, not a replacement screen, as the latter would be a relatively expensive and potentially only temporary fix. 



Chris Skelt

_________________
Chris Skelt
Lancair 320 N1990L at KIWS

user9253

Joined: 28 Mar 2008
Posts: 1927
Location: Riley TWP Michigan

Posted: Mon May 17, 2021 11:28 am Post subject: Re: Magnetized Dynon D100 Display

Upon further investigation, I don't think my D-180 display is magnetized after 

all.  I pulled the D-180 part way out of the instrument panel without 

disconnecting any cables.  Then I moved the compass around.  The magnetic 

interference seemed to be stronger under the instrument panel.  Eventually I 

determined that the control stick is magnetized and attracts the south end of 

the compass needle.  As I moved the compass around the control stick, the 

needle always pointed at the stick.  Sorry about posting an incorrect data point yesterday.

 It is worth a try for Chris to try demagnetizing the steel locking rod with a soldering gun.

  https://www.youtube.com/watch?v=g2sFp5Blg_g

_________________
Joe Gores

DougW

Joined: 16 Sep 2015
Posts: 14
Location: Washington

Posted: Mon May 17, 2021 3:33 pm Post subject: Magnetized Dynon D100 Display

Chris,



Thanks for the feedback on your experiment.  Out of curiosity, I have a D10A

out of the panel - I was going to place it near my glareshield mount

magnetic compass today to see if it produced similar results, but got

sidetracked by other gremlins, so will have to wait until Thursday to do

that check.  Will let you know what I find.



Doug Windhorn



--

nuckolls.bob(at)aeroelect
Guest

Posted: Tue May 18, 2021 10:08 am Post subject: Magnetized Dynon D100 Display

At 02:28 PM 5/17/2021, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com>



 Upon further investigation, I don't think my D-180 display is magnetized after 

 all.  I pulled the D-180 part way out of the instrument panel without 

 disconnecting any cables.  Then I moved the compass around.  The magnetic 

 interference seemed to be stronger under the instrument panel.  Eventually I 

 determined that the control stick is magnetized and attracts the south end of 

 the compass needle.  As I moved the compass around the control stick, the 

 needle always pointed at the stick.  Sorry about posting an incorrect data point yesterday.

  It is worth a try for Chris to try demagnetizing the steel locking rod with a soldering gun.

    https://www.youtube.com/watch?v=g2sFp5Blg_g 	




 I received this note from John this morning:



 ================== received from John Torode 5/18/20 ===============  

 bob,



 we have repeated the experiment with one of our d100s with the same result:  the magnetic fields emanating from the d100

 cause significant compass errors.  we believe this is from currents inside the device, not from any material becoming magnetized.

 in fact we would try not to include much ferrous material (d-subs i guess).



 my electronic compass has a definite signature from the pulsating current in the power leads to the strobe, which are some distance 

 away.



 what is puzzling is his claim that it used to work fine. one idea is that the power wire to the d100 has moved.



 we have spoken with him before (i am disappointed that any query from a customer goes unanswered), and have concluded that

 the panel is a bad place for a compass because of the many currents around.



 we do not think there is a reliable solution besides moving the compass to a magnetically quiet place.



 sorry,



 john



 ===========================================================================

 

   Compass interference issues can be difficult to track down.

   When Beech began offering the B&C SD-20 variants on the

   A36, we encountered a situation where turning the aux

   alternator on/off caused an unacceptable swing in the

   cowl mounted wet compass. We had to move it up onto the

   windshield.



   The distance moved was but a few inches but more toward

   the fringes of the magnetic field emanating from the

   rear of an energized alternator which was on the OTHER

   side of the firewall!



   Strength of magnetic forces vary with both

   distance and position. The forces do not radiate

   in uniformly dispersed spherical pattern. To make

   matters more complex, they can be strongly

   influenced by passive features located within

   the field.



   Steel tube airplanes were subject to magnetization

   of structure . . . sometimes difficult to neutralize.



   It was a rare instance that some interference

   was mitigated by demagnetizing some rogue source

   of magnetic force. The 'fix' nearly always called

   for a design change.



   We also know that the distance over which

   a given field has influence has a profound

   effect on strength.



 

   Bob . . .



   Un impeachable logic: George Carlin asked, "If black boxes

   survive crashes, why don't they make the whole airplane

   out of that stuff?"

DougW

Joined: 16 Sep 2015
Posts: 14
Location: Washington

Posted: Tue May 25, 2021 3:58 pm Post subject: Magnetized Dynon D100 Display

A little late getting this info (had said last Thursday but didn’t go to the airport until today), but here goes:

 

I have a SIRS floating magnetic compass mounted on top of my glareshield in a Glastar.  I also have a Dynon D10A which was removed from the panel a couple years ago (and has been sitting in a cabinet at home since) and which had no electrical connections to it for the following experiment.  Aircraft power was off.  Both left and right sides of the D10A screen were placed in proximity to the compass with the following results:

 

D10A right side:  No effect at 4”.  Abt 1 deg at 2” and abt 2-3 deg in contact with the compass.

D10A left side:  No effect at 6”, abt 1 deg at 4”, abt 2 deg at 2” and 11 deg in contact with the compass.  So the left side has more impact than the right side.

 

The location of the D10A when installed in the aircraft was over 6” from the compass, so I never noticed any impact from the installation arrangement.

 

Not sure what the meaning of the above is, but there is some magnetic affect not associated with current passing through the D10A (and probably other similar display devices).  It is apparent also that separating a magnetic compass from display screens of any sort, and steel aircraft frames, is probably a prudent move.  

 

Doug Windhorn

 

From: owner-aeroelectric-list-server(at)matronics.com <owner-aeroelectric-list-server(at)matronics.com> On Behalf Of Robert L. Nuckolls, III

Sent: Tuesday, May 18, 2021 11:07 AM

To: aeroelectric-list(at)matronics.com

Subject: Re: Re: Magnetized Dynon D100 Display

 

At 02:28 PM 5/17/2021, you wrote:



 	  Quote: 	
		  

--> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)>



Upon further investigation, I don't think my D-180 display is magnetized after 

all.  I pulled the D-180 part way out of the instrument panel without 

disconnecting any cables.  Then I moved the compass around.  The magnetic 

interference seemed to be stronger under the instrument panel.  Eventually I 

determined that the control stick is magnetized and attracts the south end of 

the compass needle.  As I moved the compass around the control stick, the 

needle always pointed at the stick.  Sorry about posting an incorrect data point yesterday.

 It is worth a try for Chris to try demagnetizing the steel locking rod with a soldering gun.

  https://www.youtube.com/watch?v=g2sFp5Blg_g 	


I received this note from John this morning:



================== received from John Torode 5/18/20 ===============  

bob,



we have repeated the experiment with one of our d100s with the same result:  the magnetic fields emanating from the d100

cause significant compass errors.  we believe this is from currents inside the device, not from any material becoming magnetized.

in fact we would try not to include much ferrous material (d-subs i guess).



my electronic compass has a definite signature from the pulsating current in the power leads to the strobe, which are some distance 

away.



what is puzzling is his claim that it used to work fine. one idea is that the power wire to the d100 has moved.



we have spoken with him before (i am disappointed that any query from a customer goes unanswered), and have concluded that

the panel is a bad place for a compass because of the many currents around.



we do not think there is a reliable solution besides moving the compass to a magnetically quiet place.



sorry,



john



=========================



  Compass interference issues can be difficult to track down.

  When Beech began offering the B&C SD-20 variants on the

  A36, we encountered a situation where turning the aux

  alternator on/off caused an unacceptable swing in the

  cowl mounted wet compass. We had to move it up onto the

  windshield.



  The distance moved was but a few inches but more toward

  the fringes of the magnetic field emanating from the

  rear of an energized alternator which was on the OTHER

  side of the firewall!



  Strength of magnetic forces vary with both

  distance and position. The forces do not radiate

  in uniformly dispersed spherical pattern. To make

  matters more complex, they can be strongly

  influenced by passive features located within

  the field.



  Steel tube airplanes were subject to magnetization

  of structure . . . sometimes difficult to neutralize.



  It was a rare instance that some interference

  was mitigated by demagnetizing some rogue source

  of magnetic force. The 'fix' nearly always called

  for a design change.



  We also know that the distance over which

  a given field has influence has a profound

  effect on strength.



  Bob . . .



  Un impeachable logic: George Carlin asked, "If black boxes

  survive crashes, why don't they make the whole airplane

  out of that stuff?"

sportav8r(at)gmail.com
Guest

Posted: Tue May 25, 2021 5:28 pm Post subject: Magnetized Dynon D100 Display

And now we have to worry about pilots being magnetized by Moderna and Johnson & Johnson.  It never ends.



On Tue, May 25, 2021 at 8:05 PM n1dw <n1deltawhiskey(at)comcast.net (n1deltawhiskey(at)comcast.net)> wrote:



 	  Quote: 	
		  

A little late getting this info (had said last Thursday but didn’t go to the airport until today), but here goes:

 

I have a SIRS floating magnetic compass mounted on top of my glareshield in a Glastar.  I also have a Dynon D10A which was removed from the panel a couple years ago (and has been sitting in a cabinet at home since) and which had no electrical connections to it for the following experiment.  Aircraft power was off.  Both left and right sides of the D10A screen were placed in proximity to the compass with the following results:

 

D10A right side:  No effect at 4”.  Abt 1 deg at 2” and abt 2-3 deg in contact with the compass.

D10A left side:  No effect at 6”, abt 1 deg at 4”, abt 2 deg at 2” and 11 deg in contact with the compass.  So the left side has more impact than the right side.

 

The location of the D10A when installed in the aircraft was over 6” from the compass, so I never noticed any impact from the installation arrangement.

 

Not sure what the meaning of the above is, but there is some magnetic affect not associated with current passing through the D10A (and probably other similar display devices).  It is apparent also that separating a magnetic compass from display screens of any sort, and steel aircraft frames, is probably a prudent move.  

 

Doug Windhorn

 

From: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) <owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)> On Behalf Of Robert L. Nuckolls, III

Sent: Tuesday, May 18, 2021 11:07 AM

To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)

Subject: Re: AeroElectric-List: Re: Magnetized Dynon D100 Display

 

At 02:28 PM 5/17/2021, you wrote:



 	  Quote: 	
		  

--> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)>



Upon further investigation, I don't think my D-180 display is magnetized after 

all.  I pulled the D-180 part way out of the instrument panel without 

disconnecting any cables.  Then I moved the compass around.  The magnetic 

interference seemed to be stronger under the instrument panel.  Eventually I 

determined that the control stick is magnetized and attracts the south end of 

the compass needle.  As I moved the compass around the control stick, the 

needle always pointed at the stick.  Sorry about posting an incorrect data point yesterday.

 It is worth a try for Chris to try demagnetizing the steel locking rod with a soldering gun.

  https://www.youtube.com/watch?v=g2sFp5Blg_g 	


I received this note from John this morning:



================== received from John Torode 5/18/20 ===============  

bob,



we have repeated the experiment with one of our d100s with the same result:  the magnetic fields emanating from the d100

cause significant compass errors.  we believe this is from currents inside the device, not from any material becoming magnetized.

in fact we would try not to include much ferrous material (d-subs i guess).



my electronic compass has a definite signature from the pulsating current in the power leads to the strobe, which are some distance 

away.



what is puzzling is his claim that it used to work fine. one idea is that the power wire to the d100 has moved.



we have spoken with him before (i am disappointed that any query from a customer goes unanswered), and have concluded that

the panel is a bad place for a compass because of the many currents around.



we do not think there is a reliable solution besides moving the compass to a magnetically quiet place.



sorry,



john



=========================



  Compass interference issues can be difficult to track down.

  When Beech began offering the B&C SD-20 variants on the

  A36, we encountered a situation where turning the aux

  alternator on/off caused an unacceptable swing in the

  cowl mounted wet compass. We had to move it up onto the

  windshield.



  The distance moved was but a few inches but more toward

  the fringes of the magnetic field emanating from the

  rear of an energized alternator which was on the OTHER

  side of the firewall!



  Strength of magnetic forces vary with both

  distance and position. The forces do not radiate

  in uniformly dispersed spherical pattern. To make

  matters more complex, they can be strongly

  influenced by passive features located within

  the field.



  Steel tube airplanes were subject to magnetization

  of structure . . . sometimes difficult to neutralize.



  It was a rare instance that some interference

  was mitigated by demagnetizing some rogue source

  of magnetic force. The 'fix' nearly always called

  for a design change.



  We also know that the distance over which

  a given field has influence has a profound

  effect on strength.



  Bob . . .



  Un impeachable logic: George Carlin asked, "If black boxes

  survive crashes, why don't they make the whole airplane

  out of that stuff?"

cskelt

Joined: 11 May 2021
Posts: 7
Location: Houston, TX

Posted: Thu Jul 08, 2021 1:25 pm Post subject: Re: Magnetized Dynon D100 Display

The mystery of the magnetized EFIS has been solved.  Don Jones of Dynon Technical Support offered to send me a remanufactured D100 EFIS to swap out and to test mine at their shop.  I determined that the replacement had barely measurable permanent magnetism in the same location as the original, but it was not enough to affect the panel mount compass nearby.



I installed it in the panel, did an approximate compass swing using our local taxiway centerlines as a reference for the cardinal points—close enough for our purposes as magnetic deviation is minimal here. The figure shows good agreement in cruise between EFIS and panel mount compass.  No doubt a more rigorous compass swing would improve things further.

 

Don sent me his findings. 

“I have looked into the magnetized D100.  As you noted, it is the LCD that is the source.  More specifically the thin stainless frame around the LCD.  Early version LCD's (like yours) apparently have a stainless alloy frame that can be magnetized, later versions (bright screen models) have a better stainless alloy and won't stick to a magnet. The replacement we sent has the later version.”



The panel mounted compass reads the same whether the master switch and avionics switches are on or off, and whether or not the engine is running.  Carefully following Bob's guidelines in the Aero-Electric Connection while building no doubt helped!  



It should go without saying that I couldn’t be happier with Dynon’s support, the performance of the replacement unit, and that I’m confident the problem won’t return. Many thanks to Don for his follow up that led to a successful conclusion. 

Chris Skelt 

LNC2 at IWS.

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