Problems after installing Active-breaking Mosfet

Discussion in 'Electric Guns' started by ursss, Feb 2, 2016.

  1. ursss

    ursss New Member

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    Hello guys. My gun is a M4 SA-B02 Specna Arms with 120m spring gearbox shimmed and that's all. I decided to upgrade it with 18 AWG, deans and a micro AB Jefftron Mosfet. Bought these, installed and verify. Look how wrong it look:
    1- From mosfet to trigger and back, the signal wires have the ressistance of 00.8 ohms( on the 200 Ohm scale of the multimeter).
    2- From mosfet to motor(installed) and back, the ressistance of wires is 01.2 ohms.
    Now the awkward part:
    3- Through mosfet, from battery - to motor - it's a closed circuit with 00.6 ohms ressistance. It should be an open circuit, right?
    4- Through mosfet, from battery + to motor +, the circuit is open, all good.
    5- Now, through mosfet again, from motor + to signal wire which goes to the bottom contact of the trigger it's again an open circuit with 00.6 ohms ressistance. That's allright?
    One more question:
    6- With battery connected, the voltage is going through the signal wires, and when I pull the trigger, the voltage is going as it supossed to the motor cables. Here is the question: The voltage should NOT use the signal wires at all, it's supposed to be stopped by the mosfet and leave through the motor cables just when I pull the trigger right?
    P.S.: The motor and gearbox it's shimmed and veryfied over and over again, in good conditions. Please, take a shot!
    Sorry for my bad English!
     
  2. Lefse

    Lefse Well-Known Member Supporting Member

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    There's actually a limited short circuit in an airsoft type mosfet unit because of the way the resistors are connected to the various pins on the mosfet chip. As long as the gearbox cycles normally and nothing heats up more than normal I wouldn't worry about it.
     

  3. ursss

    ursss New Member

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    That's what I'm worrying about, the mosfet heats verry bad and lipo too, just a little bit though.
     
  4. Lefse

    Lefse Well-Known Member Supporting Member

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    You're 100% sure you connected everything correctly? Sounds like your mosfet may be faulty. It's normal for the mosfet to heat up a little, but it shouldn't get too hot to touch, and ideally the battery should barely heat up. Do the wires heat up?
     
  5. ursss

    ursss New Member

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    Yeah, I cheked and recheked everything, all seems good. What concern me is the short circuit between motor + and signal wire. Also, I checked transistors with 'diode check'', one have value of 440, and the other is 0!
     
  6. ursss

    ursss New Member

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    Sibiu