Help - Micro-switch not switching...

[Pfc.Macdonald.J]

My gun died on me pre-chrono today. Popped the battery in, fired a few times - fine. Then went to chrono and...nothing. No life. 

Thought it could the motor contacts. But I've replaced them and nope. 

Then I thought the motor, but I've tested it in another gun and no issue, works fine. 

I've had the motor out and tested it and the trigger is intermittent at best; turns the motor but then cuts out and not on a full pull, like half pull and it spins. The motor won't turn the gearbox when its positioned in the grip. 

Tried all my batteries, no dice.

My gun has a micro-switch, is it dead? Anyone replaced one and has some insight? Would it be better to replace the microswitch/trigger mech with a mosfet?

Any ideas would be appreciated.

 

[Iceni]

Nuprol?

They put a microswitch in without a mosfet. It's a guaranteed failure.

You will need a new Nuprol branded switch block. If you want it to last more than a few months get a mosfet installed as well.

I don't know where you would look for the contact block, Chances are it's got a part number on it. You may have to contact Nuprol directly.

As for putting standard contacts into it. It might work. It might not. It depends on how much nuprol modified the gearbox shells, and what other bits and bobs they replaced to build the gearbox.

Putting a gate titan or similar into it might work, might not depends on what nuprol did to the gearbox shells.

Most players avoid the brand, Especially for guns. Lots of sites sell them because they know they will come back with faults just after the warranty expires.

 

[Pfc.Macdonald.J]

Thanks.

I've had it a few years now and its the first thing that's broken on it.

Found a replacement nuprol wiring set with microswitch from bullseye. 

They put a microswitch in without a mosfet. It's a guaranteed failure.

Click to shrink...

How come? How much does battery type come into this?

 

[Iceni]

Even Ni-Mh creates some arcing.

But the real issue is microswitches themselves. They operate with a sprung bar and a contact point. The sprung bars fail after a set number of activations, and the contact point is designed to wear out.

In industry microswitches are consumables. Designed to be quick to replace with minimal effort. 

Whilst airsoft deals with voltages that microswitches are typically happy with <24v airsoft also deals with currents that microswitches are not rated to carry. This carrying of current causes heat, Heat weakens the sprung bar, Switch fails sooner. 

You can get switches with higher ratings on them. Trouble is that those switches are designed to switch relays where a single action is needed to latch or unlatch a circuit. We hold closed our microswitches for extended periods allowing heat to build in them.

 

[Pfc.Macdonald.J]

Ahh. This makes things much clearer. 

So a mosfet would reduce the wear on the switch and prolong its life. Makes sense. 

I think i'll include a nanoASR when I change out the switch then. 

Many thanks for the excellent info/advice. 

 

[Iceni]

A mosfet isolates the switch. Meaning it can operate on a very low current where no heat and no arcing can happen. 

This in turn means your only limiting factor to the switch lifespan should be the wear on the contacts. That is going to be a span of many years under normal conditions.

The gate mosfets are good, I have a nanohard in one of my guns and it does far more than you would expect, Fuse, Active brake toggle, Variable lipo protection, Anti-bounce for microswitches. I'd say it was worth the extra over the ASR just because of the variable lipo protect feature. It'll mean you can ignore the battery and the fet will cut out well before you hit a dangerous level, If you loan your guns out to friends it'll mean you don't have to keep an eye on them to see if the battery is going flat.

https://www.patrolbase.co.uk/gate-nanohard-3rd-gen-multifunction-aeg-controller

For a basic Fet the Xcoretech XET304u and it's clones are my go-to fets. For about £7.50 you get contact protection on a durable proven design. The only problem is you have to do some wiring and soldering to get them in nice. 

https://www.ak2m4.co.uk/internal-parts/mosfets/acemos

 

[Pfc.Macdonald.J]

Bit of credit where credit is due.

@Iceni All your advice has been spot on.

I ordered a nanoasr and a new wiring loom with microswitch. Went to fit them and found that my gearbox had two 8mm bearing that had bust and found the contacts in the existing microswitch were covered in carbon. Replaced the bearings with some bushings. Rewired the gearbox with some sexy new 16 awg silicon wire and the new microswitch from the loom I ordered (the wire that came with it was the same as in there previously and is this rubbish, brittle 18 gauge stuff), fitted the mosfet and voila - she lives to pew pew another day!

Just wanted to say thanks for the spot on advice. And also a nod to @Sitting Duckfor an ancient post I found on here of his that waffled on about wiring, gauges and routing signal wires. Long winded but also very, very helpful. 

Thanks chaps...