MPP GPS lost, ATTI mode drifting, sudden movements and teleportation across the globe.

[FuFe]

Sorry for the wall of text, I'm trying to be as precise as I can on first post.

Problem?
Plenty GPS, suddenly switching to ATTI, and aircraft is hard to control, "teleports" thousands of kilometers.

Was unit in a crash?
None that I know of, it is second hand, been sitting on a shelf for almost 2 years.

What have you tried so far?
IMU and compass calibration 100 times, switching to former and most recent firmware, flashing double with booth DJI Assistant and DUMLdore.

What device are you using ( iphone , ipad, Samsung , etc)?
iPad mini 2

What firmware are you running ( aircraft, remote controller)?
Most recent 01.04.0500

What Go app version are you using?
Most recent DJI GO 4 v4.3.38

Any modification? (if so what)
Twisted the rear motor wires properly.

Did you change anything or install any apps? (if so what)
No.

Do you have a video or pictures of the problem? (if so post link)
FLY108 logs:
DJI Flight Log Viewer - PhantomHelp.com
CSV: FLY108_20201107.ZIP
FLY130 logs:
DJI Flight Log Viewer - PhantomHelp.com
CSV: FLY130_20201111.ZIP
Screenshots attached

Dear members,

I've been a silent observer for the past 2 weeks, read all the related posts so far, but I don't seem to find the solution to my issue, therefore I'm turning to you for help.

I've got a second hand Mavic Pro Platinum 2 weeks ago, which has been sitting for almost 2 years on a shelf, reported as not been crashed, only minor scratches it has.

The battery was completely depleted, but charged without a problem, app says 3 cycles, I was very happy.

Now the problem started as I was flying it, first switching to Sports mode and flying for 4-5 seconds in straight line it suddenly switched to ATTI mode, having 15+ satellites in view. Controlling it was very hard, and even though GPS gets back in a few seconds, the aircraft drifts drastically, not blown by the wind, as the AC does sudden drastic movements by itself and control only returns on lower altitudes where downward visioning system operates. Now this forum has a lot of cases with similar symptoms, mine has a significant difference. Mainly I'm "teleported" across the globe according to GPS.

The sequence of events are the following:
- Happens during flying, so never happened in hovering
- GPS "teleports"
- Battery bar on top switches RTH time is more than the battery time remaining (full bar yellow on top with H marker on rightmost position)
- Video feed jerks for like half a second
- App reports "Satellite Positioning Off. Fly with caution"
- Sometimes app reports that due to RTH time is much more as battery time left, it starts auto land.
- App reports "Weak GPS signal. Positional accuracy may be compromised. Please fly with caution"
- App drops a big popup stating I'm flying in a restricted zone, and I need to check a checkbox and push yes to bear all responsibility (I'm not in such a zone)
- The status light on the back of the AC turns normal blinking red. Might be low battery, or IMU error according to manual, but it is red even when AC stabilizes and RTH battery time is less than real battery time, and app doesn't state anything regarding IMU or compass

Controller signal is strong all along, never disconnects. Now I'm having this issue in both P and S modes, very constantly, 9/10 times flying, and multiple times during one flight. It is also not related to battery temperature.
I did several IMU calibrations, compass calibrations on open field right before flying to test this behavior, and multiple firmware versions double flashing with both DJI Assistant 2 and DUMLdore.

I'm attaching screenshots from flight log. I'm having like 3 hours flight time, and over 420 000m total distance which is some normalized but still impossible stat. Usually I have about 200 000+ m after a 15 minutes flight but it is modified automatically when I sync it.

Now the technical stuff:
As a lot of similar issues described here stated that this might be interference in the rear compass due to high currents in flight, I've disassembled the top part to twist the motor wires, but found out my unit already had twisted wires, though sloppy, I twisted them properly. Tested it after, but no success, same result.

I was suspected that my GPS unit is faulty, but checking the flight logs it seems that the GPS reports good LAT and LON positions all along, and the IMU LAT/LON positions are displaced, always to the same extent, one at a time, never happened both the same time, but happened both in 1 flight. (So either I'm in the Atlantic Ocean, or near Cape Town, South Africa). I'm curious if it is a bit flip, calculation error, interference, what could it be?

I'm quite sure this is a HW issue. How could I be certain which component is failing? GPS? IMU? FC?

I hope someone here has the knowledge to help me determine!

Thanks,
FuFe

Ps.: I've tested again today, in open field, with fresh IMU calibration before flight, and did it as soon as I accelerated in SPORT mode. FLY130 logs linked above.

 

[Meta4]

You have an intermittent error that's producing garbage location data, sometimes latitude, sometimes longitude.
It has nothing to do with your compass or anything that you can recalibrate.
I'd send it to DJI for repair and let them workout which component is the issue.

 

[DanMan32]

I'm surprised the battery was still good after being left alone so long, not that it's relevant to your issue.

 

[FuFe]

I was lucky with the battery, not so much with the drone. Today I took it to another test flight. Did a fresh IMU calibration at home, checked the sensors and was all very low green. Waited 15 mins, and both accelerometers were off significantly, though still green. Waited another 3 minutes, and all is back to normal. Didn't even move the AC from the place of calibration. Took it out to fly, and turned on the AC unfolded on the ground in the middle of a field, and I've received my first red error message within the app "IMU altitude error, contact DJI Support". The error went away in a few sec, needless to say, it was producing the same symptoms during flight after a few minutes. Then I took it to the nearest official service partner (I just learned that I live a few blocks away from the only one in my country

Turned out I just missed the warranty period with 1 month, pitty. They did a quick check and stated that all is OK with the drone. I insisted that it is not, described them all this in detail. They never heard of such a behavior before, but they took the drone in for a thorough diagnostics, and they'll give me a repair proposal in a few days.

I'm quite proud of my knowledge I gathered in this past few weeks on diagnostics as I could discuss the technical details with the tech guy, he also suspecting a faulty IMU, we'll see.

Anyway, even though my thread is quite dead, thanks for your support as I learned a lot from this forum altogether!

I'll report back when I get my AC repaired.

 

[dwallersv]

I'm quite proud of my knowledge I gathered in this past few weeks on diagnostics as I could discuss the technical details with the tech guy, he also suspecting a faulty IMU, we'll see.

You should be, that was some well-structured, systematic investigation and analysis. If you're not an engineer, you really deserve some props

 

[FuFe]

I've just been notified my AC has been forwarded to DJI Repair, as the only local authorised repair shop was unable to find the root cause. I'm quite affraid it'll cost an arm and leg for the rapair as I could simply buy a working second hand one instead. Fingers crossed.

Btw. I'm sort of an engineer (electronics college, IT BA), but never came accross aviation before. Just plain curiosity and systematic diagnosis I tried there. Thanks!

 

[ChrisOutdoors]

I would have reinstalled the firmware on the AC. Good opportunity to install a hacked firmware if you hadn't done so yet, free options on this very forum.

 

[FuFe]

I would have reinstalled the firmware on the AC. Good opportunity to install a hacked firmware if you hadn't done so yet, free options on this very forum.

I mentioned in my opening post I did flash multiple versions, multiple times, same symptoms with all of them. That's why I suspected it's a hardware issue. At one point I also tried hacked FW as well, nothing's changed in the behavior.

 

[flt]

Any update on what was found to be the problem?

 

[FuFe]

Any update on what was found to be the problem?

I'm just about to loose my patience.

As I gave it in for repair and have a long chat with their engineer personally he told me they'll take a look, have some test parts to narrow down the issue, shouldn't be a big deal, ~25€ for diagnosis, and repair should be ~20€ for IMU + some small hourly rate and I don't need to pay for the diagnosis if I ask for the fix.

They checked before I gave it in that I just ran out of warranty it was till end of September, bummer, but ok. They asked me to fill out a request form online, but were unable to start the dedicated machine in the shop to let me, so I filled out the form for the repair on mz tablet. The form asked if I think my issue is warranty based (cannot translate it quite exactly, it was asking what I thought). I checked it as we discussed it with the shop the AC was sitting on the self for almost 2 years. Guy taking in the case checked and said it's ok.

Now 1 week passed, and I received a notification that tha AC was forwarded to DJI, case number provided.

Another week passed by, no word from the shop, no change on the tracking number, called them. They said that they didn't even took a look at my AC, some guy checked my case flag for "warranty" without checking the serial and sent it out abroad, to the Netherlands. They said I was to blame filling out wrong. I complained, with no effect.

DJI gave a quote to the local authorised service center, who immediatelly gave me another quote in local currency. ~140€ for the repair, not a single detail. Checking the DJI case number, I've got 4 photos, 3 about minor scratces on the body, and one from the app stating connected and 9 sats fix on GPS.

Called shop again, to check, I had a feeling that this quote is only to replace these scratched cosmetic parts. They confirmed, that no mention on any electronics parts or the issue at all. Now I provided them - the local shop - messages in English, with the screenshots I've also attached here as it turned out the local shop didn't even provide any detail to DJI Netherlands in the first place. Another 3 days call confirmed they forwarded all my writings and my account info, dates I provided for where AC had issues, but they said DJI will not use it, flight log analisys only takes place if it is under warranty, or I need to pay another 50€ for it. But locals will negotiate for me with Netherlands.

I called them again, but didn't receive any reassuring info. I even asked that I understand they sent it out by mistake, but if I don't want Netherlands to replace the shell, just pay for the transport and get it back to them, will they repare it for me? Transport fee is ~28€, still I thought it will be much cheeper and effective.

Local shop promised me at least 4 times they'll gonna call me back, never happened, nor they have updated my case with any info online, I was calling them about every 2-3 days to kick this case forward.

In the end they suggested me to pay Netherlands repair as it might be the same cost for local repair in the end (strange, but ok, they didn't even look at it in the first place, and doesn't really know what to quote), and DJI will send me a replacement (new or refurbished - most likely the latter one) drone. Also took me another call to get an answer what warranty do I get if I pay up as I don't believe a thing that anyone says about the repair, I'm gonna go berserk if I get back the same AC, replaced shell and faulty flight characteristics. They said I'll get 3 months full warranty. So I paid up, attached the transaction confirmation from my bank on the 21st Dec. No word from them since, no update on any tracking number since, so I suppose they didn't even process my paiment, went on holiday. Nor they paid for DJI, so it's gonna take another 2 weeks I suppose to get anything back.

So this is it, how the only authorised DJI service center in Hungary does its business. If I'd ordered an IMU from AliExpress for 18€ I'd be flying that thing right now, most likely as I think my investigation is solid.

I'll report back when I get back the (or an) AC. I'm not putting in writing my thoughts about the service I'm paying for, I'll wait until the end, but a miracle should happen to make me a satisfied customer...

 

[FuFe]

I gave it in for repair 7 weeks ago, on 2020.11.12. after having it for only 2 weeks.

 

[FuFe]

Just a quick status here. The DJI tracking showed the "repaired" and "shipping preparation" status on 2021.01.08. It never changed to "shipped", but after 2 weeks I called the local service asking what's happening. They told me DJI have already shipped back my device, they received it in the same condition I gave it in. It means I've paid up, and neither they repaired anything nor replaced it, they have sent it back unrepaired. So my local service reported it back to DJI, and sent it in again stating the issue without consulting me. I expected some info, but at least I didn't waste time there.

I've been given a new case number to track, which yesterday showed it as "received", today I see that it is past "damage assessment" and resides in "quoted" state, which I don't like as I definatelly will not pay anything from here, I've already gave them the first quote (~140 €).

It is ridiculous. Is this the general experience of the customers of DJI?

I gave it in for repairs 11 weeks ago.

 

[FuFe]

All's well that ends well!

Let me report back that my case has finally been closed. Yesterday I received a brand new replacement drone, I had to activate it, but was unable to fly it due to very high winds. Today the weather calmed, and I had the chance to take it outside, and burned through 2 batteries, no issues arisen!

It took 12 weeks, numerous calls, travelled 4 times across Europe but I'm happy with it now!
From the serial number it seems the drone is quite freshly manufactured, so not something sitting in a warehouse for 2 years. Which is interesting as if I recall the MPP is no longer available at the distributors.

Model: Mavic Pro, build on: 17. December 2020

I hope you don't hear any further issues from me! I now just go on and geek out analyzing the flight logs to understand every bit of this bird... See you around!