no power to motor.

[Hectic]

so i loaned out my m4 today to help a n00b out, something i do often as i remember when i first started and had to borrow and rent guns and if it wasnt for those folks who helped me out id have never gotten into airsoft so i pay it forward.
Well today tue loanee was test firing the gun it work a few shots then nothin. No click no slight growl from the motor tryin to turn nothin. I though maybe the merf3.2 i have in there may have fizzled crom wet comditions last game but no it lights up fine when a battery is connected and with it removed from the gun its the same symptoms.
I pulled the stock off and checked all the wires and they seem fine too no breaks or freys.
So what is potentially my issue and how do i trouble shoot this.
Is the motor dead from the active breaking on the merf?(its only got a 4-5000 rounds on it its an echo1 stock motor)
Is it the trigger cotacts? Should it wear out so fast using a 9.6?
Thanks for any help with trouble shooting and reccomendations folks!

[L473ncy]

You didn't mention it but did you check the motor connectors on the pistol grip? Sometimes it's the easy things that we forget to check that make us waste time on doing other crazy advanced shit (ie. Is the device plugged in?). God knows how many hours I've spent forgetting the simple things only to go back to it later and see where I went wrong.

[Hectic]

Yes i shoukd have said i did pull the bottom off the grip and checked those plugs as well. Thank you tho i know i did that once or twice myself when changing grips and such.
I think ive narrowed it to either the motor is fryed or the trigger itself isnt working.
I did a simple (prolly stupid) test i unpluged the motor and touched the plugs that go to the motor together (well nearly together and tapped em together and such) while pulling he trigger and got no sparks so likely its trigger related

[ThunderCactus]

next time, just use a voltmeter >.<
If you put too much current through the mosfet you could fry it. Wouldn't be too worried about that with an NiMH battery though

Check continuity between trigger contacts when you press the trigger down
And to test the motor, just hook the battery right up to it with bare leads, you'll know right away if it's toast or not.
One mystery "motors dead" problem I came across, the brush spring had actually broken, preventing the motor from running

9.6v mini batt shouldnt hurt the contacts running straight on them
a 9.6v large NIMH will either arc them pitch black or melt them fairly quickly
If you're running a proper mosfet, you should never see any trigger wear at all
If the motor's been "cooked" by active braking, the commutator should be pitch black and just needs to be cleaned. If it's pitted, you need a new motor

[Wrath144]

Trigger post!

[ThunderCactus]

Yeah that too.
If you take the mechbox apart, put it back together, and it fires in semi once then stops. Trigger post lol
It's the cast post or screwed in post behind the sliding trigger contactor that prevents it from moving back too far

[Hectic]

You mean this lil bit

That appears to have busted off from near my finger to the left behind where the lil top portion of the trigger conection that slides back n forth


So what do i need a new gearbox shell?
Also is it odd to anyone that there is no shims in this thing i know its a bearing box but wth?


Also im tryin to figure out how this renders the gun useless the trigger mech seems to function just fine without it. Ie it goes back n forth just fine and makes contact returns to the back and reslides to contact and so on

[Hectic]

Last questions
Modify reinforced 8mm torus
Or lonex enhanced 8mm bearing gearbox?

Also aside from a caliper how can i tell what size my gearboxes bearings are. Tape measure i guess? Edit i answerd this myself its 8mm lol looked up the gun it was in the discription

[Hectic]

I lied. Tempered steel or ceramic bearings

[Wrath144]

That's the trigger post!
Steel or ceramic both work, as long as the ceramic is Kanzen.
If you don't want to buy a new mechbox shell, you can trill and tap a hole where the trigger post was and use a small grub screw as a replacement.

[ThunderCactus]

You can just replace it with a screw
drill and tap where the old post was, red loctite in a screw with the head cut off

You won't be able to see the failure unless you force the cutoff lever to move the switch

[Hectic]

Lonex or modify shell?
I dont have all the tools to drill n tap and id likely just screw it up lol.
They would be the modify ceramic ones. But ill likely just reuse the the bearings i have or the ones that come with the box (lonex comes with)
Also using a bearing gearbox does that mean i dont need shims? Edit. Apparently there was one thats right ONE shim on the big gear in the middle (spur gear.. I dunno its the big one at any rate)
And the bearing under it looks odd compared to the others

[ThunderCactus]

It's more important to shim bearings than bushings
And G&P shell if you can get one

[Wrath144]

Can't go wrong with Lonex.

[Hectic]

I can get lonex gaurder and modify locally. I guess lonex is what all the cool kids are using these days lol.
I spose i should wire the merf go the trigger while im in there and ad a sorbo and a bearning spring guide? That should increase the durability of the box and let me correct the aoe or whatever the heck its called.
Too much stuff to learn lol i just wanna shoot folks lol