wiring problems

OK when i plug the battery into my m4 it starts firing without the trigger being pulled and this only happens on safe. The gun is a jg m4 s-system enhanced with mosfet. Any help would be appreciated.

Might need some more details. Im not familiar with mosfets in airsoft guns but I have some experience with them elsewhere.

first off. what has changed since the gun worked fine? was the mosfet added when the gun was working and now it isnt? if that is the case then the mosfet is either installed incorrectly or is faulty.

Im not an AEG scientist or anything but it is also possible that the safe/fire selector is in wrong.


My first GUESS, and all my money would be on the mosfet being installed in the "wrong" order. Seeing how you aeg has only one "switch" then I am guessing that it is installed in conjunction with the trigger or gear box switch. check the wiring schematic again and make sure its all in place correctly. (it is sometimes best to test these kind of things before soldering them in place)


Of course if it has been working right with the mosfet then all of this is a waste of good posting space and hopefully one of the other guys can help you ^_^

sorry i wasn't clear the gun came with the mosfet and has be working right for about a year. i looked around the gun some more today and it seems it only fires uncontrolably when the wire is twisted a certain way. i would guess it was a short (but im no electrical engineer) but it only does it on safe so i have no idea.

It is likely that the shielding on the wire has a cut or a nick in it causing it to short out against the frame. I would pull the gun apart and visually inspect all the wires. (remember to check the ones for the "trigger" as well.)

If there aren't any obvious abrasions in the wire(s) then I would try eliminating the mosfet.


(if that doesn't do the trick perhaps another member will chime in.)


Good luck

I think i found the problem. when i was looking at the wires like you said i pulled the shrink wrap of the mosfet and one of the wires just kinda fell off so i think that may be the problem. not realy shur how i missed that. anyway thanks for the help

Nope problem man. I'm sure you would have found it sooner or later. Im having issues as well and I think im going to have to re-wire the entire gun