Hello,
Sorry I'm chiming in late, ( thanks for the alert Mark ).
rDp,
There could be several things causing the flip or instability!
First
Are all 4 motors level with each other
( a motor/arm can tweak in a crash ) causing a motor to become out of level with craft ) usually visual inspection will be enough, but another way to check is to put props on, spin by hand, check measurement from phantom top case to prop tip, then spin prop 180 degrees and measure other top from phantom shell, measurements should be equal! ( on each prop ) also check bolt holes, screw holes can break loose causing motor to be unstable, as shell is just plastic, and can crack or break easily in a crash.
( make sure all 4 props are DJI props ) aftermarket props don't have the same lift as OEM DJI props, if they DONT SAY DJI ON THEM, toss them!
Ok
If you have craft open, under the top plate is your GPS unit, remove shielding, then remove 4 tiny Phillips screws, visually inspect GPS ( Ceramic antenna for cracks ) as it can crack very easily ) causing faulty or inaccurate GPS readings, or none at all! ( if it looks good, reinstall it, and let's move on )
While open
Inspect all connections to naza, and motherboard, scrutinize every connection, wire, solder joint, check closely ( as wires can pull out of those tiny connectors ) or ( solder joints can crack or come loose )
Ok
Now we need to check your compass, gyroscope, and accelerometer
( compass ) is where you are facing on Magnetic earth ( this is what keeps bird facing one direction )
( gyroscope ) is in charge of SPINNING movements ( Yaw )
And
( accelerometer ) is in charge of all straight line movements ( up-down-left-right-fwd-reverse )
Ok
This being said the IMU, ( Inertial Measurement Unit ), takes readings from these items, constantly, I'm sure thousands of times per second, but it takes these readings, averages them out to a MODDUS, or Mod value ( MODDUS is another term for Absolute value ), so when you hook phantom to PC ASSISTANT, and under advanced tab, you'll see the MOD values of ( gyroscope, accelerometer, and compass )
Please let us know these values?
Gyroscope and accelerometer should Be Very close to 0 ( usually a 1 or .8, something like that and NOT JUMPING AROUND ) should stay pretty stable to whatever number they are.
Now Compass, you should be in a range of around 750-2400 I believe, but let us know. This will tell us if the compass is working or is whack! You can reset them if mod value is WAY off, requires a strong magnet and some patience!
( also check compass connection closely, if cover poped off, connector or wire could be damaged? )
Now if all looks good
Hook only Tx to RC ASSISTANT, do a full calibration ( both sticks, both toggles, and dial wheel if avail ( or 7th channel mod if avail )
This will recalibrate your Tx!
Next
Hook phantom to PC ASSISTANT, under basic-RC tab, calibrate Tx here again ( bother sticks, toggles, and dial wheel/7th channel mod ) this will calibrate Tx to bird, so they will be perfectly synced together.
Lastly
On a wooden table ( preferably ) do an ADVANVED IMU CALIBRATION ( Must keep bird perfectly level and stable from any movement ) I use a CUBE LEVEL, directly on top of naza unit, most use a piece of thin glass across all 4 motor shafts, level ALL directions, once level perform IMU calibration , after calibration is complete, go outside and do a fresh compass calibration.
Now what I would do, is PIN DOWN the phantom ( I use 3 two pound dive weights on each leg ) that way I can spoil up motors with props on, and phantom cannot lift off, once pinned down, rev motors all the way up, listen and look for anything weird, loud squeal , pauses in spins, or erratic behavior in any of the motors, and I'd test heat on each motor after 3-5 minutes of running motors up, if any motor temp is more than other 3, you might have a bad motor bearing?
All motors should be close to same temp usually 80-90 degrees, after 3-5 minutes of running.
Also check your camera anti-jello balls, if any are torn or cracked, can cause a wobble as well, has happened to me before.
Once all this is done and everything passes the test, try a flight
( make sure props are balanced ) this too can cause unstable flight!
( also balancing craft does not matter, naza will correct any unbalanced problems ) as I hang my tracker on one side of my phantom with no issues!
Hope this helps or at least gets you on the right track!
J Dot
