Mosfet Help

T4RGET

Hi all,

I recently installed a Mosfet into my custom M4, it was built from scratch and it works grand without the mosfet.
The problem is when i switch it onto semi it will cycle once when i press the trigger or sometimes only half cycle. Other times if i don't depress the trigger fast enough it will cycle once when pulling the trigger and once when letting it go again.

On auto it just fires semi and auto every now and again, more or less the same problem with the trigger as with semi.

It's a Raptor mosfet, any one have any ideas what may be wrong with it?

mafo

Did you replaced the selector plate spring ?

T4RGET

mafo wrote: »

Did you replaced the selector plate spring ?

yup, I got the instructions with it and followed them. As far as i can tell I did everything as I should have.

mafo

Try to stretch the spring a little and check the cut of lever for movement. Maybe is to tight.

T4RGET

mafo wrote: »

Try to stretch the spring a little and check the cut of lever for movement. Maybe is to tight.

gota open the gearbox again

I'll crack it open so, I'll get back to you in a few minutes Thanks Tom

T4RGET

Here's a picture of the springs
Top is normal stock one that came with the GB
lower one is the 'Fet's spring

DSC00279

Mando Commando

Had a second hand AEG for a while that had a Raptor in it, now the microswitch was broken to begin with so it didn't cycle anyways, but I did notice that even though the previous owner had followed the instructions for modding the selector plate exactly, the replacement spring was too compressed. Leads me to believe that the selector plate could do with an extra mm or two taken off in some cases. Pure speculation mind.

T4RGET

Mando Commando wrote: »

Had a second hand AEG for a while that had a Raptor in it, now the microswitch was broken to begin with so it didn't cycle anyways, but I did notice that even though the previous owner had followed the instructions for modding the selector plate exactly, the replacement spring was too compressed. Leads me to believe that the selector plate could do with an extra mm or two taken off in some cases. Pure speculation mind.

I'll give it a shot, reckon I'd have to stretch the spring too?

Mando Commando

Just from the pic I wouldn't think so? Although I suppose you couldn't really know till ya had it installed and got a look at it. The spring from the gun I had was like yours, with a slight buckle in it from being compressed a bit too much. I think your one looks a bit better though. I never got round to having a proper run at fixing it up as while I was scratching my head thinking about the microswitch, the guy who sold it to me had a change in circumstances and didn't need to get rid of all his stuff and bought it back.

T4RGET

Mando Commando wrote: »

Just from the pic I wouldn't think so? Although I suppose you couldn't really know till ya had it installed and got a look at it. The spring from the gun I had was like yours, with a slight buckle in it from being compressed a bit too much. I think your one looks a bit better though. I never got round to having a proper run at fixing it up as while I was scratching my head thinking about the microswitch, the guy who sold it to me had a change in circumstances and didn't need to get rid of all his stuff and bought it back.

ah alright, thanks mate

Inari

Take your gearbox out of the body, attach your pistol grip directly to the body, and put in your motor.

Physically move your selector plate with your hand, and pull the trigger. Start in safe (selector fully forward) - you should feel the trigger block. Move it until the trigger block is just out of reach, and look at the selector...is it depressing the switch on the side? It shouldn't be...that's the switch allowing it to go to full auto. You may need to file that piece back a little. I certainly had to fine-tune it. If you can get it to cycle cleanly via manual movement of the selector plate, then it's just a matter of filing until it is the right size.

I would also recommend stretching the spring and re-tempering it - the extra length does help the cut off lever engage more positively.

T4RGET

Inari wrote: »

Take your gearbox out of the body, attach your pistol grip directly to the body, and put in your motor.

Physically move your selector plate with your hand, and pull the trigger. Start in safe (selector fully forward) - you should feel the trigger block. Move it until the trigger block is just out of reach, and look at the selector...is it depressing the switch on the side? It shouldn't be...that's the switch allowing it to go to full auto. You may need to file that piece back a little. I certainly had to fine-tune it. If you can get it to cycle cleanly via manual movement of the selector plate, then it's just a matter of filing until it is the right size.

I would also recommend stretching the spring and re-tempering it - the extra length does help the cut off lever engage more positively.

I'll give that a try when i get home thanks Kev

Inari

To clarify...attach pistol grip to gearbox...not to body. This is what happens when I don't get enough sugar :P

T4RGET

Inari wrote: »

To clarify...attach pistol grip to gearbox...not to body. This is what happens when I don't get enough sugar :P

yeah figured that much, can't see the selector plate otherwise .. Haven't got around to checking it yet, hopefully tomorrow