Servo twitch at cold startup

  • Dear forum, I am a RC pilot wo started now on Jets and bought a Powerbox Mercury. I am hoping you can help - please. I am new to Powerbox systems and ran into an issue on my first unit


    This is what happens on my Viper Jet


    1 - Connect Powerbox (Mercury SRS) to battery power
    2 - Switch on transmitter (DX18)
    3 - Switch on Powerbox
    4 - All servos center, except RH aileron, which twitches (similar to OLD 35Mhz systems did it transmitter is not on)
    5 - Switch off Powerbox, switch on again immediately - everything is now OK


    (VIDEO Attached - The Video shows from step 3 through 5)


    I have replaced the servo for a new one and the new servo does the same


    Does anyone know what I am doing wrong?

  • I'm not sure it really helps, but I have an IC powered H9 Christen Eagle, and the same thing happens on all control surfaces.


    Originally this happened with an iGyro SRS and Futaba R7008. I swapped this pairing to a new airframe and it doesn't occur. This has different servos and uses a Gemini II.


    More interestingly I fitted a Mercury SRS with a Futaba R7006 to the Christen Eagle with different batteries and the twitching is back exactly as before. So I can only assume it's one or more of the servos which are Savox SC0254. I have other airframes with these servos and iGyro SRS that don't have this problem.


    I have found that switching off and back on again stops the twitching.


    Regards


    Dave

  • Hello,
    the hint with the Sc0254 is important. This servo series has problems with long leads... We found out that this kind of servos does this also on normal receivers...
    Is it only a short "twitch" or a jitter for longer tme?

  • Richard,


    In my case, they move erratically and a with a significant movement until the power is cycled. I'll post a link to a video later if I can, and I'll also test them one at a time


    The leads in this model are not very long - in fact no extensions on the rudder and elevator - plugged directly into the Powerbox iGyro or Mercury.


    This is the only airframe, or more accurately, set of servos that does this. However these are the oldest set I have - now on their third Christen Eagle, probably purchased in early 2013.



    Regards


    Dave

  • I've done a bit more checking and with the Mercury it's only one servo that oscillates, with the iGyro SRS it was all of them. So given my other airframes with the same servos and different ones, it seems some property of the servos is the cause.
    Dave


    PS no need for a video - it's self explanatory

  • I know this is an older thread but its a situation I am having with a powerbox....my issue is the servo is

    franticely jumping up and down violently fast.... going through the Power Box... if I use the very same

    extensions just plug into the receiver I have no Issues... so logic has it to me there is an issue with the

    power box ?

    should I set up my own thread or pursue this question on this thread?

  • So I think I have solved my own problem..... here is what I have found... its apparent that Power Box sets up pulse width updates to

    the servos... in MS miliseconds... the box was set at 18ms... I turned it down to 9ms and NO MORE TROUBLE..

    so the BIG >? here is for MKS High Voltage Servo 767... what is the correct setting for these servos....in MS... like I stated

    I have them set at 9ms right now with out any jitters..... the actual Power Box manual states to contact the manufacture of the

    servo.. I am thinking.. it should be contact the manufacture of the Power Box... lol what say you ?