DIY rear compass cabling fix

[Logger]

Is the rear compass integrated with the GPS or standalone
So in putting all this puzzle together we are still missing a piece. I want to know if the rear compass is an integrated model combined with the GPS (my bet) or a standalone unit, identical to the one up front one.

If someone is knocking the top off theirs or has an inventory in pieces @Thunder-drones , any chance you could take a peek and report back with an image.



Just two screws by the looks (image courtesy of Nils Rohwer) . I don't particularly want to decapitate mine to answer this Q when there are others lying around in pieces.



A google search for Mavic GPS reveals this as the part. I suspect the GPS chip on the black board is actually glued to the alloy plate and will come out as one.

So if someone can remove these two screws and take a peek beneath we will have the answer. If there is no other device up in there then we know the rear compass in integrated.

Knowing this will go some way yo explaining why the compass order has not been reversed in firmware.

 

[Former Member]

Remove 2 Phillips screws, pull up the plate, unit is clipped in, just release the clips and out it comes. It's not attached to the metal plate.

 

[Logger]

**** that was quick..
So bingo - that pretty much confirms the rear compass is integrated with the GPS.
Thanks @Thunder-drones

 

[Former Member]

**** that was quick..
So bingo - that pretty much confirms the rear compass is integrated with the GPS.
Thanks @Thunder-drones

Yep and its alot easier to get out than the GPS on the P3 series. The Mav continues to amaze me with it's repair-ability. This one just pulls out very easily.

On the P3 you had to peel the adhesive off the top cover and be careful not to rip it in the process. Then restick it if the adhesive was still intact. The P3 also had a very vulnerable compass and compass cable in the front gear that would tear easily upon impact and you had to take the whole P3 apart to get to it. I havent seen a single Mav with compass damage from impact. They are smart and getting smarter every version, keeping the compass out of harms way. I really love the engineering. I actually enjoy repairing them.

 

[DroneTone]

Reading this thread, I was concerned about possible compass errors with my Mavic, (even though I hadn't had any to this point).
I also wondered if my Mavic had the untwisted rear motor wires and if it was worth it to risk opening the top just to check.

I figured for a start I should fly the Mavic and see if I could induce the described compass error.
To test this, today I did a straight line two mile flight, out and back, all in Sport Mode and at full throttle.
If there was to be any Compass errors, I figured this should induce one.

During the flight in DJI GO4 there were no compass error messages and no battery power messages or warnings.
Next I uploaded the DAT log into CsvView and checked out the MagZ Front and MagZ Back for differences.
However to my untrained eye, they look fairly consistent.

What I'd really enjoy is hearing a second opinion...
Attached is a pdf showing the magZ Front and MagZ Back for this particular flight.

Also- sorry, for some reason I couldn't get the vertical scale to appear on the right side of the CsvView graph.

 

[Logger]

Yep and its alot easier to get out than the GPS on the P3 series. The Mav continues to amaze me with it's repair-ability. This one just pulls out very easily.
..<snip>.. I actually enjoy repairing them.

Makes you life easier hey

This should really be for another thread - but was just looking at few Mavic serial numbers to see if we can work out which ones are likely to be effected. So people don't go jumping at shadows.

Can you glance at your inventory to see if this is gels with yours.
14 alphanumeric digits 08QDDxxx120yyy . The ones I have seen show characters 12345 & 9,10,11 I have bolded are constant. But I only compared 7 serials. Does this schema match with the ones you have lying around? If so the xxx & yyy characters contain the differing information.

Also if nothing else, the compliance label has chanced slightly at some point. More recent models have replaced the rubbish bin with an avatel compliance logo. Not sure when this occurred. But seemingly no trash can is a recent thing.

 

[Randy]

Makes you life easier hey

This should really be for another thread - but was just looking at few Mavic serial numbers to see if we can work out which ones are likely to be effected. So people don't go jumping at shadows.

Can you glance at your inventory to see if this is gels with yours.
14 alphanumeric digits 08QDDxxx120yyy . The ones I have seen show characters 12345 & 9,10,11 I have bolded are constant. But I only compared 7 serials. Does this schema match with the ones you have lying around? If so the xxx & yyy characters contain the differing information.

Also if nothing else, the compliance label has chanced slightly at some point. More recent models have replaced the rubbish bin with an avatel compliance logo. Not sure when this occurred. But seemingly no trash can is a recent thing.

It gels with mine (08QDDAT012001S) hopefully I can eventually find out whether my wires have the factory twist or not based on this.



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[Logger]

Yeah that matches Will jump across to the other thread and set the sleuths at it. When did you get your unit @Randy? Nov/Dec perhaps?

 

[Randy]

Yeah that matches Will jump across to the other thread and set the sleuths at it. When did you get your unit @Randy? Nov/Dec perhaps?

Late November


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[Ewan Morrish]

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.

Yes can confirm the removal on one screw from each arm to perform the rotation. 5 minutes of work to fix an annoying issue. All subsequent flights have been without issue. Hope this helps.


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[Logger]

Thats terrific. Lets see if we can confirm your build date Ewan. You got yours end of OCT so should be one of the first. What are the two characters after 08QDD on your serial number? a "9" perhaps or "A", then what ?

We can then try pin down the build dates effected vs not.

 

[Ewan Morrish]

Serial is 08QDDAC01xxxxxxx


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[pitchmagic]

New FW out!! Will that deal with this problem or not? There is also an updated GO app. Its not showing in appstore yet though.

 

[Logger]

Serial is 08QDDAC01xxxxxxx

Good one thanks. 12 Oct 2106 so ties in with your late OCT delivery.

 

[Randy]

Yeah that matches Will jump across to the other thread and set the sleuths at it. When did you get your unit @Randy? Nov/Dec perhaps?

I got brave enough to pop the top off of mine and take a look, the wires were NOT

twisted as you can see in the picture showing the one i did next to the one that I hadn't twisted yet. It was very easy, just take the screws out of the top and bottom, lifted the top off and took the 2 screws out of the boom mount and rotated, easy peasy, can't wait till it warms up (-40) this morning so I can see if it fixed the problem.


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[Logger]

Thanks for the update @Randy. So yours have a serial with 08QDDAT. So likeley built on OCT 28 and confirmed as a non twist. The change to the wiring config in factory was seemingly made late Nov. Be good to find some slightly later builds that don't have the twists.

My replacement from DJI is seemingly a DEC 1 build and is twisted BUT it may possibly have been done later as a mod/repair by them.

 

[Randy]

Thanks for the update @Randy. So yours have a serial with 08QDDAT. So likeley built on OCT 28 and confirmed as a non twist. The change to the wiring config in factory was seemingly made late Nov. Be good to find some slightly later builds that don't have the twists.

My replacement from DJI is seemingly a DEC 1 build and is twisted BUT it may possibly have been done later as a mod/repair by them.

You don't have to take the top completely off to see if they're twisted or not, just take about four screws out of the back and pry the top up a little and you can easily see them.

 

[bernie124]

My non twist, that I've got DEC 7 has a serial with 08QD DB2.

 

[Starz]

You guys are an asset to the MP group. Amazing what a little digging turns up. Sounds like my late December order date may put mine in the twisted group. Does that sound correct?

 

[JTS]

My non twist, that I've got DEC 7 has a serial with 08QD DB2.

That was built 2 Nov 2016 if Logger is right (and I'm sure he is).