Problem with Mercury and MKS Servos

  • Hi everybody,


    In my Mini Diamond Jet, 4 original servos were not strong enough (elevators and flaps). I changed for MKS 747 servos.

    I did not have any trouble with the previous graupner servos.


    I can clearly hear a regular pulsation and can see and feel a small oscillation at any position.


    My set up : Powerbox Mercury / Jet DS 24 / 2 RSAT. The settings are those recommanded.


    When I change the frame on the powerbox or on the radio the oscillations frequency change but remains.


    When I test the servos without the Powerbox (connected directly to a classical receiver), I do not have any pulsation or oscillation. So this is the Powerbox that has trouble to handle MKS 747 servos.


    Question : does anyone have the same problem and what can do Powerbox to solve it ? New software version ?


    Sorry for my poor English and regards from France.

  • Hello,


    a simple receiver doesn´t have the output amplifiers... If I can´t see the problem I can´t fix it. I don´t have such servos here.

    If you say changing the input framerate from the receiver, it seems that the update rate makes problems, but I´m wondering if the output framerate from the PowerBox doesn´t change things?

  • I will try do to a video this afternoon but you won’t see a lot. We hear a clear periodical noise and feel the vibration. The servos move but really only a little around their position.

    No problem with any other brand or type of servo with this same configuration.

    When we change the output frame from Powerbox make the phenomenon vary but it remains...

  • Richard, for MKS no problem with their servos because they work fine when directly connected to a simple receiver without Powerbox.


    Question :

    - do you have an idea to fix this issue ?

    - if not, can I fly with this curious behaviour ? What is the risk ?

  • Hello,


    I could say the same: with other servos it´s working... bad answer. I fear I can´t fix it from here. Would need such servos to perform some testing with capacitors in front of the servos or pulse line... Where are you from? Maybe an additional pulse amplifier from use may solve it...


    I would have no problem with flying that. But should be fixed for long term.

  • Hi Richard,


    Thank you for your answer.

    I am from France...far away from you.


    The servos are fixed in their compartment with glue so it would be difficult for me to remove them and send one to you.


    How can we proceed now ? Can you buy one of these to perform some tests (MKS 747 HV) ?


    Cédric P.

  • Hi Richard,


    Some news : I received the pulse amplifier, thank you very much.


    Unfortunately, after test it doesn’t change anything to my problem.


    Can you manage to get one of this servos to make some tests ?


    Thank you again for helping me to solve this issue, seems like a compatibility problem between Powerbox and MKS 747 servos.

  • To sum up :

    - MKS 747 + JETI RECEIVER + RADIO JETI = NO PROBLEM

    - MKS 747 + POWERBOX + OTHER RADIO = NO PROBLEM

    - OTHER SERVO + POWERBOX + RADIO JETI = NO PROBLEM

    - MKS 747 + POWERBOX + RADIO JETI = PROBLEM


    At this point, seems to be a compatibility issue between JETI and POWERBOX but only when using MKS Servos.


    What can I do now ??? All of them are top products that should manage to work together...!