It is double feeding. The motor has loads of tork and the spring (wich I was told is an M130) is weaker than a Madbul M120 I have. I talked to Juggles and he thinks it may be either a cut off lever or a selector plate issue. I'm going to dig in to that later today and I'll post my findings.

The "C" in 20C is your discharge rate. Lets cover the basics first: the lipos rebranded by the suppliers and supposed "manufacturers" do not indicate if this is your continuous rate or if its your burst C rate. Burst rate in this case does not mean your ROF, it means the most powerful rate your battery will dump out power. Due to the fact that this is not evident on the batteries (hence no way to tell even with my background in RC lipos), there is a toss up between what lipo battery you ACTUALLY have.

At 11.1v a 1600 mah 20C lipo battery is putting out 3200 mah at full charge

At 7.4v your 2150 mah 20C lipo battery is putting out 4300 mah at full charge

Think of the "20C" bit on your battery designation as how far you can open up the faucet to fill a glass of water (aka the discharge rate), at 20C you're already near full blast (the cup runneth over) as lipo batteries were NEVER designed to work on anything without an electronic speed control (a full functioning version of any of the ASCU and PTW, all these mosfet based systems are effectively only half an Electronic Speed Control device).

Try a 15C 7.4 volt battery OR if you don't need a lipo, switch over to a PROPER 8.4v NIMH pack from your local hobby store. You can also try a 12C lipo battery from Frank. Your gearbox is the equivalent of a differential with no clutch and a motor connected to it, now you have an electronic brake on it. You want the very best so if you go and do get an NIMH pack, make sure its a quality pack that says it has MATCHED cells. As a matter of fact, I HAVE helped someone overcome this issue, he now runs an 8.4v NIMH battery despite the size, and it works perfectly.

Lipo fun tidbit:

IF you see that your lipo battery is kaputski after 50 or so charges AND you've taken REALLY good care of it (as in don't charge over 1 amp, no gouges on the pack itself, etc etc), chances are you've got a B rated pack, this is highly undesirable as B rated lipo packs are to be used with caution and not expected to last long (50-70 charge cycles max) due to high levels of resistance during the pack build.

Hi, I bought myself an ASCU and just finished installing it to my M4 G&P AEG.

The only trouble I had was to make sure that the SAFE, SEMI and AUTO would work well. I Bended and added some tin on the little strips of metal used to know in what mode we are.

It seems to be working, although I'm concerned about two things:

- Firstly and the one I'm most concerned about: the mosfet heats up pretty fast. I don't have any experience with MOSFETs in general, so I don't know if it normal or not.

- Secondly, I can't really do shots too quickly in SEMI. When I quickly tap a second time the trigger after I've tapped it once already, sometimes it won't shoot again.

Does it do that to anyone else?

Yes the MOSFET heats up. What kind of battery are you using? Lipo's and lifepo's will heat it up faster.

Why did you add strips of metal to the contacts? All you have to do is bend them upwards a bit.

I had a similar problem but made a few changes so not 100% sure what solved it.

The only thing I can think of is to check your cutoff lever for clearance. Did you remove the cutoff lever spring?

I'm using a 7.4V G&P Lipo. But it's good to know that it's normal that it heats up.

About the metal contacts, I didn't add strips, I soldered some tin on them because otherwise I would have had to bend them a lot and I was afraid they would break. But that part is working so I'm not worried.

About the shooting issue. I did remove the cutoff spring. I really don't know what could be causing this...

I am having a double beep error with my ascu. Whether I put the motor in the gearbox or not I get a short burst from the battery, approximately 3 shots if I leave the motor in the gearbox, before the unit gives me the double beep and wont fire again until I unplug the battery and try again. After plugging the battery back in it just does the same thing. I have insulated my selector plate, the motor is the stock motor from the SRC Proline Guns, and my battery is an intellect 1600 mah. Neither of my chargers detect a problem with the battery, and it works fine in another AEG. I can't figure out why the damn thing wont work.

make sure the cutoff lever is able to move freely. open it up and cycle the sector gear completely and watch how the lever contacts the switch. there should be a small gap as it ends the cycle.

to me, it sounds like when you double tap the trigger quickly, the previous cycle has not completed yet. other than that, I can't think of anything without seeing it.

the switch contacts are pretty resilient and can take some careful bending. if tinning them works for you, great.

Anyone tried installing this in a VFC Scar...H to be specific? Im running into the one shot then it beeps issue indicating an improper selector. I trimmed according to spec but considering that a VFC Scar is a little bit different than a normal V2 GB Im not sure of the amount youre supposed to cut is correct.

It's possible, but I thought it would work anyway.

Here's a video of the behaviour of the unit on my G&P M4. The gearbox has 8mm bearings, G&P gears, G&P M120 Motor, SP90 Guarder spring which gives me a 345 fps. I use a 7.4V G&P Lipo.

YouTube - Airsoft ASCU

Basically, it doesn't shoot everytime I pull the trigger as I'd like it to. But again. Maybe I tap it too quickly and it only shoots if the previous cycle is over.

The good thing is that, in SEMI, the piston stops at the exact same place after every single shot (I put a dot on the piston through the holes in the cylinder to check). It's not true in AUTO (it's not bad though). This is why I recommend like other to keep the Anti Reversal Latch.

[edit]Is it just me or does the ASCU consume a lot more power than the regular switch assembly?[/edit]
[edit2]Maybe I just shimed my gearbox too tight...[/edit2]

I found the ascu takes more juice to run too. I finally tore into mine to figure out why mine went tits up many weeks ago. I had the motor neg lead slip out of place and get chewed up by the gearbox :( oh well. Mine had the shit wires on the motor leads so I'll replace them from the main board with something better. Gonna mod my selector plate at the metal contact strip a bit too so in semi it makes better contact with the ascu switch assembly.

also going to try and make me some 9.9v life batteries that will fit my crane stock from some a123 cells and see how they go. Not so happy they'll only be 1100mah but I got enough for 4 packs for free so why not try.

I finally did it!

ASCU + battery both fit inside an M4 stock tube!
(the battery is a G&P 7.4V 1200mAh 15C, and the stock is a magpul PTS UBR).

Here's a video : YouTube - Airsoft - ASCU Mosfet + Lipo Battery in M4 UBR Stock

It took a lot of effort, but in the end, it seems to work fine.

I haven't tried it in a game yet, and I have a few concerns:
- first it seems that the battery consumption is a lot higher with the ASCU.
- then, I don't know how it'll hold in the long term. I did have to completely rewire the unit...

I'll post pictures later of the changes I made, if some of you are interested.

for some reason my ASCU didnt come with a Fuse....................

That's kind of odd. The blade fuses are pretty cheap though at automotive or possibly electronic stores.

sorry to drag it up again but i have the exact same problem - custom made gearbox - even the shell is custom etc - but no matter what i have the issue where my trigger only first a set number of times per minute. to be honest i think its limited to stop overheating etc. its not the battery as I'm running a hyperion 35c 11.1v 3300 mAh so cycle speed is insanely fast so its defo the mosfet that limits the number of times it will cycle in semi auto - i get about 28 rps on full so like i said - defo not a cyling issue.