DIY rear compass cabling fix

[Randy]

I was waiting for the .DAT from the flight where you had the incident. The .txt does not have enough info. If you want to see if your problem has been fixed then we'll also need the .DAT for a flight after the fix with Sport mode, full elevator, and the same heading as the first incident (about 38 degrees)

Haven't done that yet, been flying every day (airplanes) and this persistent high pressure has been given us -30 to -40 nights and about 8 above in the day, it's gotta end soon!

 

[ScrappyMavic]

So what does this mean? Is it possible that twisting my wires may have taken care of this? Has anybody looked at the post twist files to compare? I have 2 metal roofs here, it was never a problem with the phantom 4, but maybe the Mavic is more susceptible to this, I don't know.

My personal opinion is that wire twist won't help this particular issue. I've seen this same ATTI / TBE problem when running on the front compass (no noise) and on rear compass after noise fix. A better bet is an absolutely pure compass recalibration.

 

[Lukappaseidue]

Is there somebody that could be so gentle to tell me Step by Step how to twist the rear arms wires ( i know that i am asking too much, but a video tutorial would be the best)
Thank you very much

 

[Randy]

My personal opinion is that wire twist won't help this particular issue. I've seen this same ATTI / TBE problem when running on the front compass (no noise) and on rear compass after noise fix. A better bet is an absolutely pure compass recalibration.

There's a reason why DJI started twisting them, and speaking for myself, I've flown four times since the twist and the GPS and compass are much more stable. Still too cold to really put it through the paces, but I'll know more when it warms up here. If you go to your compass in the app and the calibration shows "good", is it really necessary to recalibrate? If the app doesn't tell you to calibrate should you do it anyway? I brought a phantom 4 from Alaska to California this winter, flew the heck out of it there and never did a compass calibration the whole time I was there, and zero problems, so I don't understand why the Mavic is so different.

 

[Mr Spock]

Is there somebody that could be so gentle to tell me Step by Step how to twist the rear arms wires ( i know that i am asking too much, but a video tutorial would be the best)
Thank you very much

Look at my earlier post in this string.
DIY rear compass cabling fix

 

[Lukappaseidue]

Look at my earlier post in this string.
DIY rear compass cabling fix

Thank you very much Mr. Spock. Is or necessary ti remove the top of the mavic? I have fear to void warranty.

 

[Atomicbear]

Thank you very much Mr. Spock. Is or necessary ti remove the top of the mavic? I have fear to void warranty.

Read through this whole thread please... the answer is "no" you don't have to remove the top, but you should read through everything here so you have better knowledge of what causes it, what to do to fix it, and how to do it without removing the top. I'm not trying to be mean, but this question was asked and answered a few times already in this thread. If you would have read it, you wouldn't have to ask the same question again. Thanks. I'm done venting.

 

[Lukappaseidue]

Read through this whole thread please... the answer is "no" you don't have to remove the top, but you should read through everything here so you have better knowledge of what causes it, what to do to fix it, and how to do it without removing the top. I'm not trying to be mean, but this question was asked and answered a few times already in this thread. If you would have read it, you wouldn't have to ask the same question again. Thanks. I'm done venting.

Thank you for your reply.
I ask for video tutorial because I am Italian speaking and for me it is not so easy to understand technical language to do the fix ....

 

[Mr Spock]

Thank you very much Mr. Spock. Is or necessary ti remove the top of the mavic? I have fear to void warranty.

It depends. You can do it without removing the top but you wont be able to twist all the way, maybe around 4 turns. In my opinion is best to open it only if you know what you are doing but this way you can twist the wires all the way if you like and you have full control of what you doing. The warranty i guess is void even if you twist without opening it any way becuse you would have removed the legs etc.

 

[Lukappaseidue]

Thank you very much

 

[xblackxopsxsecretsx]

is it bad to ignore the compass redundancy switch in sports mode warning and not either fix myself nor send in for adjustment?

 

[Randy]

I was waiting for the .DAT from the flight where you had the incident. The .txt does not have enough info. If you want to see if your problem has been fixed then we'll also need the .DAT for a flight after the fix with Sport mode, full elevator, and the same heading as the first incident (about 38 degrees)

What does TBE mean?

 

[msinger]

TBE = Toilet Bowl Effect

 

[Oingo Boingo]

Never had compass issues.... If u really worried abour EMF just use a small ferrite core ring. Thats 10 times more effevtive than twisting wires

 

[npmullins]

Hi all, i have been getting the compass redundancy switch error message, in sport mode with aggressive maneuvers, i did the wire twisting mod last night, yet to do the test flight.

A word of warning to others how are yet to do this, i found the unclipping of the plastic clips on the front nose of the top plate very difficult to undo. I used a plastic prying tool and still struggled for 5 mins to make it pop open. But once i was in the arms came off every easily after removing the 3 screws.

Ok so I finally got to test the mavic after doing this mod and have done 5 flights with no sign of that compass error message. So I am very happy with the results.

 

[Randy]

Ok so I finally got to test the mavic after doing this mod and have done 5 flights with no sign of that compass error message. So I am very happy with the results.

Spring has sprung here, I have flown mine about a dozen times since the wire twist and not a single ATTI mode or loss of GPS, I'm a happy man, I feel like I can trust this thing, loving it more everyday, looking forward to the summer!

 

[beatnik]

I'm just reading this thread and the causes of my compass switching. My bird shipped in Oct 2016, one of the pre-orders. Here's my Sigview. Would I be better off twisting or just sending it back for warranty fix? Blue is sport, but I see lots of Redundancy Switch Warnings just flying around normal P mode.

 

[beatnik]

After putting 4 twists in the rear arms, did a test. Z Mag Rear Peak to Peak around 130 in sport mode. I guess time will tell. I did have a Compass Redundancy Switch when I first powered on and sitting on the landing pad. Compass 1 was reading around 100 and compass 2 around 10 just sitting there when it switched.

 

[Pol]

This thread is on the right track! As a quick late at night investigation, 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. (maybe could have though) I pushed each arm back on, tightened the screw, and went for a flight for no good reason. What I found was that no matter how hard I tried, I could not get compass error and could not get redundancy switch. Even going sport mode, full elevator + full throttle at same time, no compass error. Now in the past I would easily have gotten compass switch every time. I proceeded to fly two full batteries in sport mode, not able to get compass to switch.

Now then using @BudWalker 's miraculous and life saving CsvView, I compared the rear compass noise under full speed sport mode to previous .dat captures I had. The plots are below, and you can see previously I had about 250 counts pk2pk on rear magZ.Back and I now have about 150 counts pk2pk.

This tells me the compass interference is highly sensitive to the routing of the small amount of wire slack inside the Mavic body. Most likely all I did was slightly move the wire by pulling on it. I'm not sure my "fix" will last, and you can see front compass is still much cleaner than rear. However I'd be very confident now that just adding some twists to the rear motor wires would totally fix the issue.

Old .dat prior to my wire pull (full speed sport mode)
View attachment 6710


New flight after my wire pull (full speed sport mode)
View attachment 6712

Hi ScrappyMavic,
I'm very interessted in the graphs you are showing here.
Can you point me to a tutorial that lets me learn how to get these graphs and annalyze (aka read) them?
Thank you very much in advance!

 

[beatnik]

Hi ScrappyMavic,
I'm very interessted in the graphs you are showing here.
Can you point me to a tutorial that lets me learn how to get these graphs and annalyze (aka read) them?
Thank you very much in advance!

If you scan through this topic there is a good step by step. Basically download the free app, you don't need the Datconv app just the CsvView, Load DJI Assistant 2, connect Mav, look at flight logs, copy the one you want to your computer. Open CsvView, open the DAT file in CsvView, click in the SigPlayer window and add/remove signals tab and select Magz.Front Magz.Back and flystate to compare flight mode to compass noise during normal and sport mode. Draw a box to zoom into areas. You can measure signal peak to peak with cursor.

To post here, choose Copy to System Clip Board tab, start a reply and hit paste and the view will be included in your reply!

HTH