Partial firing causing issues with MOSFET

[Lambster]

I'm going to try to explain this the best I can.

 

At my main site, it's single fire only, so if I pull the trigger and quickly release before fully pulling it the motor turns but not full. Another pull usually releases and it's off again, sometimes it jams.

 

Now I thought a MOSFET would help prevent this and always complete a spin. But I can't find where I read this so maybe it's just not true. I can't see how it would be true as the MOSFET doesn't know where the motor is, it can only guess.

 

Now on to my problem, as mentioned previously, if the spring wasn't released, a pull or 2 on the trigger usually sorts this. However with the MOSFET attached, it doesn't. In fact it borks my gun and stops it firing until I take the MOSFET out.

So with the MOSFET attached, if I pull the trigger but let go before the spring is released, then pull again, I get a click and the LED on the MOSFET goes bright for a second or so. No amount of pulling will fix it. I have to remove the MOSFET, fire, then attach the MOSFET again.

 

So what's going on here? It's a NEW* 2014 Burst Wizard King Kong Super 2 MOSFET.

 

 

 

 

 

 

 

MOSFET, MOSFET, MOSFET, MOSFET, MOSFET....I felt like it needed typing a few more times...

[dex]

Need a bit more info on your gun: what is it? is it stock or upgraded/customised internals? what spring? what battery? how long have you been the gun? I presume from what you've said you are using the BW2 in "plug and play" fashion?

 

As for diagnosis - ditch the mosfet for now - start with the battery - how old is it and is it fully (balance) charged? Try it in a different gun or try another good battery in yours.

If not that then I would look at the motor - then the gearbox drivetrain (gears, shimming, piston) - then wiring and trigger contacts. You need to eliminate 1 factor at a time.

[Lambster]

It's a G&G GR16 CQW. It was stock internals before I had the mosfet. It was doing it then. I've just upgraded to shs 13:1 high speed gears and a jbu high torque motor. Fully shimmed and regreased. Also obviously out the mosfet in plug and play as you said.

 

Spring is stock, had the gun for 2 months or so. Battery came with it. I have 2 and both do the same. I have a new one which I need to try.

One is an 8.4v nimh and other is 9.6v nimh

[jcheeseright]

In order for a mosfet to be able to completely eliminate semi lock ups in a V2 gearbox it needs to monitor the position of the sector gear, BTC Spectre or Chimera drop in units will do it but they're nearly the cost of a combat machine!

 

Personally I'd upgrade the wiring, get a cheaper mosfet like a gate pico or nano ab, put a high torque motor in there and use 11.1v batteries, should solve your semi auto lock up problem :-)

[dex]

What spring does it have? If it's anything under an m120 you're looking at a pre-engagement issue with those 13:1 gears.

[Lambster]

As I said, it's the stock spring. Not sure on its rating.

 

I don't think it can be pre engagment from my understanding of it. I only have a 13rps ROF and it was firing at 310 fps before the upgrade.

 

It never happens on full auto. It's only if I pull the trigger but let go before the piston is released.

 

The techie from my team has told me that he think that when the spring is all the way back the gun is Drawing too much current, so the Resetting fuse kicks in As it thinks I have a short. He said I'd have to remove the fuse from the mosfet. Which is something I don't want to do tbh.

[Lambster]

Just taken the gearbox apart again to have a look for any signs of the issue but can't see anything that would be cause for concern. However, I now have a strange noise of the motor after a Burst every so often. I took a video of it.
AEG Problems:

http://youtu.be/LEhwzzeuSgQ

https://www.youtube.com/watch?v=QPYobtxWlVY

https://www.youtube.com/watch?v=N9wQ3pINN5M

[dex]

Good videos. From what I can see/hear you have several issues (that I can identify at least):

- The shimming and or motor height isnt great, your getting a fair amount of squeal

- Looks like you have some overspin - this would be even worse running on a lipo

 

If it were me I would do the following

- take down the gearbox, clean it and do a general inspection of the internals.

- replace any worn parts (in your case look at the piston rack for wear)

- replace any parts not suitable for a high speed setup (stock bushings for example - use good quality bushings or bearings)

- re-shim and set the motor height exactly

- use an M110 spring at least or an M120 and short stroke

- set the AoE with sorbo (this is important in a high speed setup)

- do a break in run with just the gears and motor and a decent lipo (eg with a good discharge rate that can fully juice your motor - i have a feeling that your nimhs are not up to it) - i would advise against running high speed gears with a nimh

- fit an active breaking fet such as the nanoAB to cure the overspin (the BW2 is not AB and wont do much for you anyway unless you wire it into your trigger contacts)

- re-grease with lithium grease for the gears and silicon grease for the o-rings etc

- see what happens

[Samurai]

That noise is because either you forgot the anti-reversal latch or it's spring or for some reason (bad shimming) it can't engage.

[Lambster]

Thanks guys.

The Anti-Reversal latch wasn't in correctly. It's sorted now.

 

It seems to be ok at the minute but will have to see how it performs at the next game.

Hardwiring the MOSFET is definitely something I intend on doing.

 

As the the internal wear, I had a look at the parts and it all seems to be fine. I'm going to correct the AOE and get a M110 as you suggest as that should lower my FPS with the AOE fix but bring is back up with the spring I hope.

I'm also going to revisit the shims when I go back in to the gearbox.