Asg scorpion issue in semi

[Stodgy]

Evening all,

im struggling to diagnose a strange problem on an asg evo scorpion. 

In semi the bb just fall straight to the ground. But on triple or auto it works properly (on 11.1v)

Weirdly I tested it on 7.4v and that works fine. Guess I will just run it on that unless someone can help. 

Currently has shs 18:1 gears in it and a new prommy purple bucking and nub. Also there is no sector delay chip (asg has one as standard in the gun)

I did find something online where someone else had the same problem and they fixed it with a weaker tappet plate spring. 

Im flummoxed and cannot work it out and have never seen this before so any help will be greatly appreciated 

 

[Robert James]

If you have facebook, join the ASG scorpion group and ask for help in there. Simon Moore will probably help you out

 

[Iceni]

Sounds like the tappet plate is getting caught on the shims. Meaning the air nozzle and tappet plate are not fully forward. It's normally caused by the sector gear been shimmed high so there is gear pressure on the side of the tappet plate.

The 11.1v battery could also be running fast enough to be the tweaking the sector, Pushing it out a little. Check the bushings/bearing on the sector, and check the shims.

If you have no shims on the sector, or the shimming is poor (lots of side movement) then this can also grab the tappet plate. Again the 11.1 will put more side load on the gears due to the added speed.

It might be doing  it on auto and 3rnd burst as well. But the next BB is smacking into the dropper. Do you find the range on some shots seems very short and lacking in backspin. Or you get frequent fliers on auto.


 

 

[Stodgy]

I checked the tappet plate and it was clean with no signs of dragging. 

Alas I think the mosfet is now dead as I’m not even getting a beep when I connect the battery. Going to leave it for a bit and retry it again in the new year. Flummoxed and need to look at it again when I’m fresher and less jaded with the whole thing. 

 

[Iceni]

There have been a few issues with them. Soft gears is one of the more common complaints but I see you have already redone the gears!

The fet is a bit harder to diagnose. You can get a full drop in replacement for about £50, perhaps cheaper if you look about. It doesn't solve the feed issue tho.

http://www.gearofwar.co.uk/?product=asg-scorpion-evo-mosfet-unit
 

£40

https://urbanairsoftuk.com/product/asg-evo-replacement-ec-mosfet-unit/

If you are handy with a multimeter it might be worth doing a loom check, I wouldn't even bother trying to look at the mainboard tho. It's not a fet it's a micro-controller, and far more  complicated than it needs to be, with the 3rnd burst and the magwell switch. You might get lucky and find a failed diode or in-line fuse but I can't see one on the mainboard that is a likely culprit for a total power loss failure.


The SS34 diodes in the daughter board would probably be the first thing I would test if I wanted to start troubleshooting. There only rated for 3amps. And don't deal with current spikes and reverse voltage very well. They also get hot and shocked been almost mechanical they can have a high failure rate.

The daughter board itself looks to be a power factor controller. Splitting a lower voltage and current off to the mainboard, and acting as the switch for the motor. So in essence it is the mosfet.

The daughter board can be purchased separate of the mainboard so it might be worth the gamble of just picking that part up to see if it fixes it.
It's about £20 for the daughter-board without the mainboard.

Firesupport have stock of just this part, but if you want both FS want more than what GOW are selling them for.


If you've changed the motor, Given it more current than usual from a lockup or tight gearbox, Or simply the diode isn't perfect then these can all contribute to those diodes failing. It's a poor design by ASG to use them for voltage regulation. There are better potential dividers that are less fussy about input variations. It's one of the reasons I like the bog standard fet design like the Xet304u. There is very little to go wrong on them.

G&G have had issues with ETU's as well for much the same reason. Poor design, without a generous enough tolerance to both voltage and current.