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Troubleshooting Help: Recovered Mavic After 32 Days Underwater
212 2 2019-11-5
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vertibird
lvl.1
Flight distance : 330302 ft
United States
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So...I'm flying my Mavic last month at a local reservoir, filmiing a water skier about a mile offshore, when I get an "Undervoltage Protection Loss: Land Immediately" warning.  I haul butt back to shore, but the drone abruptly shuts down mid-flight and falls into the water about 15 feet from shore. Me and my friends dive in to try and recover it, but the water is murky and gets too deep too fast and we leave empty-handed.


32 days later, the reservoir is 12 feet lower. I go back and amazingly we find it in two feet of water.

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To quote James Kirk: "I don't like to lose". It's fresh water immersion and it was likely (mostly?) depowered when it went in. So I disassemble the airframe and place the parts in a sealed container with a tub of Silica Gel dessicant for four days. I then thoroughly clean the mother boards with electrical cleaning spray and brush out the silt. I reassemble the parts, connect a fresh battery, push the button and cross my fingers, fully expecting this to be an exercise in futility....

...And it freaking starts up.  The LEDs light up, there's the startup tones, the motors do their little twitch and the gimbal starts it's pre-flight gyrations. Holy ...! I grab the controller and start the DJI app and it connects! IMU initialization is successful, Front & down obstacle cams work. GPS acquires position, Ultrasonic sensors work. I can't believe it.

But it's not all good news:  There's no video. The gimbal won't acquire the horizon, and cycles through it's self-test every 30 seconds or so and the compass won't calibrate. I also have two persistent errors on the display: "Air Encoder Error 0x800000" and "No.3 ESC Error". There's a touch of corrosion on the rear left motor (which is No. 3, I believe) and it's a bit clunky to turn so these may be related.

So I think the Main Board is good, and possibly the Video Board since the front cameras are on that and they work. The ESC board is gonna be a pain to replace if I cant get the No.3 system working, the compass board is probably shot and I might have to preplace the No 3 motor.

Which brings us to the limit of my electronics intuition. Any ideas on how I can further troubleshoot these systems and figure out which parts I'll need to replace?

And before you ask: No, I don't have the DJI coverage...



IMG_0376.jpg
2019-11-5
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DAFlys
Captain
Flight distance : 1059396 ft
United States
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Plenty of parts on ebay - https://www.ebay.co.uk/sch/i.htm ... +parts&_sacat=0  good luck with the repair.
2019-11-5
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DJI Tony
Super Moderator

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Hi, we're sorry to know about the mishap that happened to your drone. Unfortunately, there are no possible troubleshooting steps that can be applied based on the situation of the drone. Moreover, for the sake of security,  we indeed don’t repair water damaged drone. Because aircraft consists of large quantity of sensitive electrical components, after it is water damaged, electrical components may be corroded, thus affecting its stability and security. Through the related tests, the repair of water damaged units needs to replace all the relevant components, and it is possible that the cost of repairing a water damaged drone is far higher than buying a new drone. Therefore, we advise that water damaged units are ineligible for a repair service. If you would like to contact our support with regard to this situation, please refer to the link below. Thanks for your understanding and cooperation.

www.dji.com/support

2019-11-6
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