Mercury SRS - Servo Malfunction

  • Hello Richard,

    I am new to this forum. I currently have a Mercury SRS w/o GPS. I built a brand new 100cc 3D airplane setup. Unfortunately, I have burned up 3 brand new HV servos with this Mercury Powerbox. During the initial setup, everything was working fine for the 1st 4 flights. On the 5th flight, I had a brand new Futaba 9177 elevator servo lock up in flight and lost the plane. I purchased a new airplane, and in this setup, I'm running Savox 2290hv servos. During the setup phase, I mounted all servos without servo arms or linkages. I powered up the Mercury powerbox and all surfaces seemed to be working well. After about 3 minutes, I noticed a sharp flash and the rudder servo burned up. I replaced the servo and powered it back up. It immediately burned up an inner aileron servo. I'm at a loss. This is the 1st time i've incurred any electrical issues with an airplane build. I have the Mercury setup in Acro Mode and voltage setup at 7.4v. I am running dual aileron servos on individual channels. Is there something in the mercury programming setup that may be causing this issue? Not sure what to do at this point. I purchased this powerbox from Chief Aircraft just this year. I have a call in with them and currently waiting for their return instructions. Any idea what may be happening? Appreciate your help!!


    Tim

  • Hello Tim,


    a PowerBox - any type is not able to burn servos... There are two factors which are necessary to run a servo:

    1. Power - regulated by the PowerBox, voltage is always lower than the battery input. Even the regulators are damaged, the voltage is never higher than the battery. As you use HV servos - you never will run in a overvoltage problem.
    2. Pulse: The framerate of the pulses can be adjusted in the PowerBox. From 12ms to 21ms. 12ms is the fastest, new digital servos will work fine with that. Even with bad pulse output, a modern digital servo cannot be destroyed.

    I would do following: Send the servos to the manufacturers, ask them to check if they can find out what was wrong. Of course we also can check the PowerBox, but due to the explanation above, I don´t think this is the problem!

  • Tadango,

    I didnt have the sero arms or linkage on a the servos when it happened. I was not moving the sticks when the servos burned up.


    Richard,

    I understand what your saying however, this occured with 2 different brands of servos, one Futaba 9177 and 2 savox 2290hv servos. all 3 servos were brand new. At this point, I dont want to plug any more servos into the box without fear of losing more servos. Ive already lost 450.00 in servos. Chief Aircraft responded and said I would need to send the powerbox back to the Germany mailing address for warranty work/service or replacement. I just want to make sure the box is gone through and repaired or replaced or at the least, given a clean bill of health. Please help....


    Tim

  • Hi...i am a new user here. As per my knowledge voltage is always lower than the battery input. Even the regulators are damaged, the voltage is never higher than the battery. As you use HV servos - you never will run in a overvoltage problem. Also the framerate of the pulses can be adjusted in the PowerBox.


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