na5n
lvl.4
United States
Offline
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If you have an ESC problem, there is a "soft" failure where at least one of the MOSFETs has been damaged, but has not failed. Then, there's a "hard" failure where one or more MOSFETs has fully failed (they usually fail in pairs).
If your Phantom is still apart as shown in your photo, plug in the top with the GPS cable. Then move the motor wires so they are not touching the six MOSFET chips. If it's put back together, that's fine also. Take off the props. Insert the Phantom battery. Turn on your RC then a normal start up of the Phantom battery. Let it do a normal initialize until it has 6 sats or more. In other words, ready to fly. Do the CSC to turn on your motors (remember, no props). Leave them at idle for a good 30 seconds. Listen for any change in pitch that might indicate one motor is slowing down, or slowing down then speeding back up. Speed up your motors and listen for an even increase in pitch, or if one motor not sounding like the others at higher speed. An uneven motor sound is abnormal and may indicate a "soft" ESC failure. All four motors at should hum along at the same exact speed with very little change.
When you do the CSC to turn on your motors and the Phantom battery suddenly turns completely off, this is the battery protecting itself from a short circuit inside the Phantom. This is usually the sign of a "hard" ESC failure. Usually a MOSFET pair fails as a short circuit across the battery and causes the battery to shut down. This would indicate a failed ESC board more than the motor.
Keep in mind, if you have a "soft" failure, a pair of MOSFETs are partially damaged. Do not attempt to fly with an "anemic" ESC. Replace the ESC. Also keep in mind - with a soft failure and you run your motors, the motor current may be enough to cause the bad MOSFETs to completely fail. This will normally shut down the battery and accompanied with a puff of white smoke from the bad ESC arm. No more guessing if you have an ESC failure!
If you are comfortable with the above tests that the motors and ESC are operating normally, then put on the props and do a test with a fully charged battery by letting it idle with props, and ensuring the plastic top shell is not rubbing against any of the motors (their shape can sometimes get distorted on even a minor crash). If all is well, then lift it up 10 feet or so, then down, then up a few times, let it hover, and listen to the sound of the motors and props, or for any movements no quite right from your stick commands. If it seems OK, it is then a judgement call if you think things sound properly for a normal flight. If it doesn't sound or respond quite right, then immediately land it to be conservative and safe.
This is not theoretical troubleshooting, but my experience fixing several ESC failures.
Good luck, and let us know what you find and your observations.
Paul |
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