ArduPilot problem (Everything goes crazy). *Problem solved: bad Rx.*

Hi, I recently bought ArduPilot with an IMU and a shield for my EasyStar.

I have wired it up like the guide on the Google Code page showed.


When I turn it on to test it, I can move the plane an the control surfaces will counter move like they should in the stabilizing mode. And the MUX light turns on and off like it should.


But then suddenly, all lights on all the boards, including the receiver go completely crazy.

All servos stop dead for a couple of seconds before they go completely of the hook, even the elevator servo broke loose from the fuse ones.

The plane doesn't respond on any of the commands from the transmitter. I'm not even able to turn of the MUX, and even when the MUX-light turns off, the servos still behave like chikens without heads.

Sometimes it even throttles up.


The only thing that seems to help a bit is shutting off the transmitter, then it stops. But when I turn the transmitter on again, same problem.

This problem has also happened after the transmitter was turned off, but I only experienced this ones.


The only thing I can do to stop it, is pull out the battery and wait a couple of minutes. Put it in again after a few seconds doesn't help.


I have removed the shield and tried again without luck, I have checked the wiring, I have even twined the servo wires and tried to removed any possible interference but nothing seems to helps.


I have the newest code, but I don't think it is the code because stabilizing mode seems to work flawless until something triggers it to go wild.


I can't fly it in manual mode either, because when this problem suddenly kicks in, it even jams it in manual mode.


There is no radio interference that triggers this problem, of that I'm sure.


My Tx/Rx is a Hitec Optic 6 Sport with Hitec HFD-08RO (35 MHz) and I haven't had any problems with them before.


I haven't been able to fined any post about the same problem. I have found a few with the same symptoms, but never quit the same problem.


Hope somebody can help, thanks.



(Conclusion: If you don't bother to read this thread, this problem was caused by a bad Rx. After changing the Rx everything works fine.) 

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You seem fairly certain that it isn't radio interference, but it sounds somewhat similar to a radio problem I once had on 72mhz. I would remove the AP from the plane and test with just the RC hardware (receiver and servos) and see what happens. some aligator clips and a voltmeter to the servo rail to monitor if you have a constant 5V to the RX might help also.


I think this could also be a bad battery, perhaps dropping voltage lower than nominal for your receiver.


If it were me, I would test the AP by loading the HIL simulator code (I'm not certain that exists for original AP?) and see how it behaves in the simulator with just the receiver connected. If after several flights that is ok, connect servos to the APM and continue testing. The servos should respond just as they would in the plane.

Could also be a power issue. How are you powering the board?
Also, power up all of the equipment with servos plugged directly into the Rx. The positioning/layout of the gear may also introduce some noise.

I didn't fiend HIL for the original, but I will try to monitor the voltage tomorrow to see if it is a bad battery. (I have only used the same battery for the test.)

I will also do some more test like you and John Church suggest, and report back later.


I also thought the gear to close together would make some noise/interference, but after pulling all the gear out of the fuselage, and test again, I don't think that is the cause of the problem.

The board is powered from the Rx, and the Rx is powered from the ESC.


The ESC is a Hobbyking SS Series 25-30A, and the battery a Turnigy 2200mAh 3S 20C Lipo Pack.

Do few cheks;


1. Measure the supply voltage at the servo connector at time when every thing is connected and powered on, the +ve supply voltage should not be much less as compared with the measured value of the supply voltage from the ESC when no load is connected.  If supply voltage drops drasticaly down to say 4.5 - 4.7V on load then the SMD regulator "7805" inside the ESC is gone and you have to replace it.


2. Fully open the antenna of your transmitter and also keep the antenna wire of the receiver almost straight, keep the transmitter away from the receiver at around 2 meter and transmiter batteries should be charged fully. Now try to operate.


With the above mentioned steps your problem should be resolved.

I measured the + and - from the servo bay and it was about 4.75 V, it went down about 0.2 - 0.3 V a few times but it was quit steady and ArduPilot didn't go nuts.


Then I measured the output power from the ESC to the ArduPilot board, and this was also about 4.7 - 4.75 V. This voltage was kept at a steady rate until the craziness began, then suddenly the voltage jumped all the way down to 2.5 V and the up again to 4.75. It did this a couple of times until I had to pull the battery. (No other way to stop it.)

I don't know what triggered it, I throttled up a bit, played with the servos, but this happened when I did nothing.


I tried two different batteries with the same result, so I don't think it's the batteries.


I also found another problem when it behaved somewhat like it should. After a couple of seconds, the MUX would not go off at all. But it still got signals from the Tx since I could "nudge" the control surfaces.

I also noticed when I had the flight mode switch turned on, and turned off the Tx the ArduPilot would apply full power on the throttle. When the flight mode was turned off, and the Tx turned off ArduPilot continued like it would before.


I don't know if this is a new problem or caused by the other problem. (I experienced this before the voltage drops.)


I don't have a clue what the SMD regulator "7805" is, but could that be the problem for the symptoms I wrote above? And if, is it because it's a cheap Hobbyking SS Series 25-30A?

what code did you load?


Change your ESC.
I have loaded ArduPilot 2.7.1 and for the IMU: ArduIMU 1.8.2.
Would you recommend a Hobbyking SS Series 25-30A or should I go for something more expensive?

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