Potential Damage to MOSFET

[OwenA]

During a game I had to change battery, the tamiya housing came off and I stupidly rushed and replaced it the wrong way and plugged in, sparks from connection and gun fails to function at all now. Tried different batteries, knowing that wouldn't work but tried anyway, hoping.

Can anyone tell me the probable damage?

Any experience with similar situation?

I assume mosfet is bust, fuse looks ok but I read mosfet will go before fuse.

 

Many thanks

[concretesnail]

Basic fuses won't protect polarities. Unless the mosfet has its own protection then it likely dead I'm afraid. Replacement will most likely be the simple option.

[OwenA]

No worries, as expected. Cheers for the reply

Follow up question, do you think it will just be the mosfet I need to replace or is there a chance the etu is damaged also? 

[Rogerborg]

What gun is it?

 

We'd just be guessing, and a very basic multimeter will take the guesswork out of it.

 

Worse case, you can bin off all the electronics and just install a basic trigger switch.  AK2M4 is fairly low on stock, but still has options for both V2 and V3: https://www.ak2m4.co.uk/internal-parts/trigger-switches

[concretesnail]

It likely the mosfet only if that has popped first then it should have broken the potential circuit and as a byproduct protected the etu but

As Roger mentioned, knowing the rif and parts is large part of making an better guess and testing with a meter would be the only way of knowing without starting to replace parts.

[OwenA]

Its a g&g 308 mbr with g2h etu and mosfet. I am going to test it when I get a hold of a multimeter. Hopefully just the mosfet and I will plug in a perun g&g upgrade as I've heard good things.

[Rogerborg]

Ah, right.  Sorry to hear this, it's always a risk with Tamiya.  And yes, Perun mosfets are pretty decent, I'd consider that an opportunity to do an upgrade.

[OwenA]

Yeah won't be using tamiya again, very cheap feeling. Deans seems much more solid.

[concretesnail]

Deans are a solid bet, lots of airsoft folk use them. I tend to favour the xt connectors as I usually have a pile of them about for flight batteries and rc stuff as they are good for keeping out the damp.

[OwenA]

Ahh nice. I've not come across xt connectors before, fairly new to all this. 

Cheers for all your help guys!

[Rogerborg]

If I were rewiring again, I'd probably go to XT-30 or XT-60 instead of Deans, but Deans is pretty good too, and some airsoft guns are switching to it as standard now.

[OwenA]

Ahh okay cheers I'll keep XT in mind for future. The perun is wired to deans so I'll stick to that for now. Gotta beat tamiya anyway! 

[Rogerborg]

Yup, Deans is just fine, although you can occasionally find a couple of connectors that don't want to match up perfectly.  Still much better than Tamiya.