DIY rear compass cabling fix

[BudWalker]

So the question is, since all of our MPs are still under warranty, should we pursue an official support ticket and try to send the unit in for repair, or do we risk voiding any warranty and do the surgery ourselves?


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I believe that DJI has been fixing these under warranty upon request. But, for a variety of reasons a lot of pilots would rather fix it themselves.

 

[flyNfrank]

So the question is, since all of our MPs are still under warranty, should we pursue an official support ticket and try to send the unit in for repair, or do we risk voiding any warranty and do the surgery ourselves?


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The warranty info states that dji can replace your aircraft if they deem it needing replaced. More importantly, they also state that at anytime they can replace your aircraft with a refurbished unit. So you just never know.... And getting someone else junk, is almost like being sent another persons used underwear. When you do the work yourself, you learn, plus you always know what you got.

 

[flyNfrank]

Twisted is always better. Just the effect is smaller the more distance there is to other sensitive components. The arm is pretty far away from everything. But having the wires twisted there as well definitely won't do any harm.

In looking at my data in CsvView, one of the compasses appear to display more noise then the other. I really was somewhat shocked to see my wires were already twisted on both sides. So that only leaves the motor wires in the rear arms as being the culprit.

 

[BudWalker]

In looking at my data in CsvView, one of the compasses appear to display more noise then the other. I really was somewhat shocked to see my wires were already twisted on both sides. So that only leaves the motor wires in the rear arms as being the culprit.

That is a little surprising. Can you provide the .DAT so I can take a look?

 

[Logger]

Twisting the wires inside the arm alone would not help the problem. I am referring to twisting the arms so that the cables is the body turn 3 to 4 times like others describe.

Mr Spock I am of the view this arm spin process has indeed been achieved without lid removal. By both @ScrappyMavic and @Ewan Morrish earlier in this thread.

#14 @ScrappyMavic
...I took the single screw out from each rear arm near the pivot without taking anything else apart. I thought, if there is enough wire slack maybe I could pop the arm off, give a few rotations, and put back. What I found is there was barely enough wire slack to slide the arm off and see a tiny bit of wire. Not enough that I felt comfortable spinning the arm...

^^^^ Got scared then plucked up courage and went ahead and did it vvvvv

#15
... I couldn't stop there. I removed each rear arm again with the single screw. I pulled out gently as far as I could until it could freely rotate. I gave each arm 3x rotations clockwise allowing wire to twist, and then replaced.

#16
I had to go further. I pulled off the rear arms again and gave them 2x more clockwise twists. This makes 5x total. At this point, the last rotation was feeling fairly tight and I was putting some strain on the wires that made me uncomfortable. I screwed the arms back on and went flying in sport mode.

#22 @Ewan Morrish
just to confirm this has fixed my Mavic also. I did 4 rotations on each back arm. No more compass redundancy switch messages.


Seems to me it can be achieved by removing the single screw and pulling arm out gently. Hopefully either of these two chaps can confirm this is how they did it, without top removal.

I would think taking the top of will lead to a better job as you can see what you are doing. But it is a more difficult fix requiring more disassembly.

 

[BudWalker]

Mr Spock I am of the view this arm spin process has indeed been achieved without lid removal. By both @ScrappyMavic and @Ewan Morrish earlier in this thread.

#14 @ScrappyMavic
...I took the single screw out from each rear arm near the pivot without taking anything else apart. I thought, if there is enough wire slack maybe I could pop the arm off, give a few rotations, and put back. What I found is there was barely enough wire slack to slide the arm off and see a tiny bit of wire. Not enough that I felt comfortable spinning the arm...

^^^^ Got scared then plucked up courage and went ahead and did it vvvvv

#15
... I couldn't stop there. I removed each rear arm again with the single screw. I pulled out gently as far as I could until it could freely rotate. I gave each arm 3x rotations clockwise allowing wire to twist, and then replaced.

#16
I had to go further. I pulled off the rear arms again and gave them 2x more clockwise twists. This makes 5x total. At this point, the last rotation was feeling fairly tight and I was putting some strain on the wires that made me uncomfortable. I screwed the arms back on and went flying in sport mode.

#22 @Ewan Morrish
just to confirm this has fixed my Mavic also. I did 4 rotations on each back arm. No more compass redundancy switch messages.


Seems to me it can be achieved by removing the single screw and pulling arm out gently. Hopefully either of these two chaps can confirm this is how they did it, without top removal.

I would think taking the top of will lead to a better job as you can see what you are doing. But it is a more difficult fix requiring more disassembly.

You're right. I missed all the stuff after he said he decided not to try it.

 

[Egika]

In looking at my data in CsvView, one of the compasses appear to display more noise then the other. I really was somewhat shocked to see my wires were already twisted on both sides. So that only leaves the motor wires in the rear arms as being the culprit.

More doesn't say much.
How much more is it?

 

[flyNfrank]

That is a little surprising. Can you provide the .DAT so I can take a look?

I attached the csv of the .DAT. After looking again it wasn't as much as I 1st thought. But it was enough to get me to open the top cover and investigate. At this point at least I know what I have.

So which of the 2 compasses is considered the main compass leaving the other the back up?

 

[ScrappyMavic]

Mr Spock I am of the view this arm spin process has indeed been achieved without lid removal. By both @ScrappyMavic and @Ewan Morrish earlier in this thread.

#14 @ScrappyMavic
...I took the single screw out from each rear arm near the pivot without taking anything else apart. I thought, if there is enough wire slack maybe I could pop the arm off, give a few rotations, and put back. What I found is there was barely enough wire slack to slide the arm off and see a tiny bit of wire. Not enough that I felt comfortable spinning the arm...

^^^^ Got scared then plucked up courage and went ahead and did it vvvvv

#15
... I couldn't stop there. I removed each rear arm again with the single screw. I pulled out gently as far as I could until it could freely rotate. I gave each arm 3x rotations clockwise allowing wire to twist, and then replaced.

#16
I had to go further. I pulled off the rear arms again and gave them 2x more clockwise twists. This makes 5x total. At this point, the last rotation was feeling fairly tight and I was putting some strain on the wires that made me uncomfortable. I screwed the arms back on and went flying in sport mode.

#22 @Ewan Morrish
just to confirm this has fixed my Mavic also. I did 4 rotations on each back arm. No more compass redundancy switch messages.


Seems to me it can be achieved by removing the single screw and pulling arm out gently. Hopefully either of these two chaps can confirm this is how they did it, without top removal.

I would think taking the top of will lead to a better job as you can see what you are doing. But it is a more difficult fix requiring more disassembly.

Nice summary @Logger, I did indeed do everything without removing the top. Only the single arm screw on each side. I don't think the direction of rotation matters unless there is some inherent starting twist to which you are adding. For now my best recommendation would be 4x clockwise rotations after gently sliding arm cylinder out of socket. If you can't gently slide it far enough to freely rotate, then probably abort and do the full top removal fix. It's possible some Mavic's don't have enough slack exposed inside the body to support the easy fix.

 

[pitchmagic]

Nice summary @Logger, I did indeed do everything without removing the top. Only the single arm screw on each side. I don't think the direction of rotation matters unless there is some inherent starting twist to which you are adding. For now my best recommendation would be 4x clockwise rotations after gently sliding arm cylinder out of socket. If you can't gently slide it far enough to freely rotate, then probably abort and do the full top removal fix. It's possible some Mavic's don't have enough slack exposed inside the body to support the easy fix.

Thanks, I will do this today!

 

[Stealthmatt]

@ScrappyMavic - is it possible you can do a quick video or picture guide on exactly what you did?

Also is there any way to see if your mavic has spinned wires or not with the way you have done it?

 

[BudWalker]

I attached the csv of the .DAT. After looking again it wasn't as much as I 1st thought. But it was enough to get me to open the top cover and investigate. At this point at least I know what I have.

So which of the 2 compasses is considered the main compass leaving the other the back up?

The trick is to put the SigPlayer in Single Y Axis mode so that the signals are on the same scale.


When you do that the front and back look like this.

The pk2pk looks to be about 130 for both.

 

[pitchmagic]

It is possible to remove the torx on the arm(not the one on the body) and pull out. However the cables are short and you might damage the cables. Because of this I did the full monty and opened the top cover. The hardest part was opening the front clips. Gahh. It worked though. I removed the arms, took out the full length of the cables and twisted approx. 7-8 times. Tucked everything together and pressed the cables on the sides. The cables are very stiff and not at all like regular silicone cables but they might handle more current? Next up is a test flight and log checking.

Before:

After:

 

[Strafe1]

Well done!

 

[bernie124]

Just finished my mavic and the before and after pictures look the same as those of @pitchmagic. What I found was this shielded HF wire directly underneath the motor wires. You can see it in the "Before" picture of @pitchmagic on the lower right corner. I'm not sure, but it could the antenna wire of the right front arm. If so, it would be another reason for twisting the whole length of the wires after removing the top cover and not just the rear section by only removing the rear legs.

BTW, bought mine on 7th of December in Germany.

Thanks to all who described the problem and the solution!

 

[flyNfrank]

The trick is to put the SigPlayer in Single Y Axis mode so that the signals are on the same scale.
View attachment 7191

When you do that the front and back look like this.
View attachment 7192
The pk2pk looks to be about 130 for both.

That is very good to know, wish I knew of it sooner. I now feel like the CsvView tool is even more an asset knowing this.

Does the compasses function as 1 compass, or is one compass responsible for front half, and the other the back half?

Btw, thanks for pointing out the Single Y Axis mode.

 

[Mr Spock]

So the question is, since all of our MPs are still under warranty, should we pursue an official support ticket and try to send the unit in for repair, or do we risk voiding any warranty and do the surgery ourselves?


Sent from my iPhone using MavicPilots

People did that and they got refurbished Mavics back (not their units) with marks on them etc...

Sent from my SM-T810 using MavicPilots mobile app

 

[Mr Spock]

According to this it's not possible to twist the wire bundle without removing the top. Once the top is off remove these two screws
View attachment 7164

and the motor arm assembly comes off. Twist the assembly 5 or 6 times and re-install.

Thank you!

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[Mr Spock]

Mr Spock I am of the view this arm spin process has indeed been achieved without lid removal. By both @ScrappyMavic and @Ewan Morrish earlier in this thread.

#14 @ScrappyMavic
...I took the single screw out from each rear arm near the pivot without taking anything else apart. I thought, if there is enough wire slack maybe I could pop the arm off, give a few rotations, and put back. What I found is there was barely enough wire slack to slide the arm off and see a tiny bit of wire. Not enough that I felt comfortable spinning the arm...

^^^^ Got scared then plucked up courage and went ahead and did it vvvvv

#15
... I couldn't stop there. I removed each rear arm again with the single screw. I pulled out gently as far as I could until it could freely rotate. I gave each arm 3x rotations clockwise allowing wire to twist, and then replaced.

#16
I had to go further. I pulled off the rear arms again and gave them 2x more clockwise twists. This makes 5x total. At this point, the last rotation was feeling fairly tight and I was putting some strain on the wires that made me uncomfortable. I screwed the arms back on and went flying in sport mode.

#22 @Ewan Morrish
just to confirm this has fixed my Mavic also. I did 4 rotations on each back arm. No more compass redundancy switch messages.


Seems to me it can be achieved by removing the single screw and pulling arm out gently. Hopefully either of these two chaps can confirm this is how they did it, without top removal.

I would think taking the top of will lead to a better job as you can see what you are doing. But it is a more difficult fix requiring more disassembly.

Thank u! I knew i saw these posts. Just have to find that screw now.

Sent from my SM-T810 using MavicPilots mobile app

 

[Stealthmatt]

Guys, I did mine last night too - I took the top off.

Just be-careful of the front, because when you try and pry it open, the plastic on the lip is very weak and may indent when you try and wedge it open