battery wires smoking/heating up on newly rewired v2 gearbox
 

As a complete noob in gearboxes, I need help. I have gotten comfortable enough in a gear box to try rewiring a gearbox from rear wired to front wired, but it went sour on me. I had a g&g gear box sitting around, so I wired it to the front and put it into my dboys m4. However, the battery connections get super hot really quick, and actually started smoking once! lol now i make no bones, this is a pretty ambitious project for my current skill level, I know, so please no flaming here. This is a practice run, if you will.
Back to the problem at hand. Im having trouble getting the motor to turn the gearbox. Did I shim the gearbox wrong? Everything seemed to turn fine before I put the motor back on. Is the motor not getting power due to the wires overheating? I'm totaly clueless here. what happens is the gear box cylcles properly a few times, then just stops. And yes, my battery is charged!
Help, anyone?

Are the wires connected correctly? Specifically between the trigger switch assembly and the motor.

Are the motor connectors to the proper polarity?

Provided the gearbox is internally good it would be wiring issues. The rapid heating/melting of wires is due to overload, either there is a short some where, or a wire is on the wrong location causing the motor to attempt to turn in reverse, hence, the jam and overload.

I didnt change anything, aside from the location the battery wires entered the gearbox.
Polarity? Red to positive, black to negative. If I reversed that I do believe the motor would turn in reverse, causing damage, or zero movement due to the anti reversal latch.
Shorting? maybe... cant think where though. Everything looked fine...

I would double check everything,

What battery connectors are you using? Make sure they are wired up the right way as well.

If the wires are getting super hot, while you are holding the trigger down, while the mechbox is not moving, then you likely have the motor jammed up too high and it's not turning the mechbox
Did you run both motor wires to the back of the grip?
And does the motor turn when the end plate is not on the gun (motor moved away from bevel gear)?

Tamiya

What kind of battery are you using? If it's too weak and cant turn the motor, you'll get the same effect.

Well I think I found the problem. I must of shimmed one of the gears to much, causing them to hardly turn at all. Gears reshimmed, now the gearbox cycles just like it should. However another problem has arose. the bbs barely come out at all. On semi auto no bbs come out, on full auto they kind of just poop out randomly. Iv seen this before when my tappet plate broke, but the tappet plate is fine... *face palm*

that's an air leak
either the mechbox isn't seated properly, or something was assembled right

An air leak... What can cause this? The mechbox seems to be seated very well, I'm pretty sure everything was assembled right, but I might have to let a pro decide that for me... Is there a chance its not shimmed right yet? I think some of the gears may have a small bit of play yet, which I do believe can affect the tappet plate, but I'm not to sure how...? Any other things that can affect air seal?

remove the lower receiver, and push the air nozzle back, if it springs back with no resistance, the gears haven't been shimmed into it. But you can squeeze the tappet against the mechbox shell, then it wouldn't spring forward very fast or at all