AU3G won´t fire "semi"
 

Hi forum users!

No matter how I pull the trigger...my JG AU3G only fires on auto...any idea about?



Thank you in advance!

Im assuming by you saying "no matter how I pull the trigger" means you are aware of the two-stage trigger where depressing it half way fires semi and pulling the trigger all the way back fires full auto.

From what Ive heard the sear behind the trigger tends to be very finicky. Posting this in the Doctors Corner will yield you better response from our local gun docs, sorry I can't be of much help.

The AUG is finicky with this but it should still fire in semi-auto on a medium depress. The AUG has a unique system for semi/full auto where a half-pull of the trigger will engage the contacts but a full press will engage a section set of contacts on the rear of the trigger that acts as the sear and sets it on full auto.

If it doesn't, then you cut-off lever is worn out and needs to be replaced. I have the same problem on an AUG on my workbench right now.

Yes...I know that half-depressing would make it work on "semi" but...it doesn´t work...

Have you any photo of the part?
It would be great!


JR

it probably comes from the switch inside the mechbox, I 've had the same problem: the two little metal blades are to far apart, which makes you have to press more the trigger to get a response, and at that point the only reponse you get is full auto.
Pull those blades closer together and you'll have juice on the semi again.

So you have to take apart the mechbox and trigger assembly.

I would also guess it's the cutoff level. It's a rather common problem on many JG guns. I've had it happen to a couple of mine. A new cutoff lever permanently fixes the problem.

I've seen similar problems in two Echo1 P90 gearboxes. On one they were too far apart causing only full auto to work (and no reaction while in semi). On the other gearbox, the two metal tabs were actually too close, causing the trigger switch to have contact for too long while returning (thus full autoing even if only tapping the trigger slightly).

On yet another (Marui) P90 gearbox, a friend is having trouble with only getting full auto. The strange thing is that it only appears when he uses 11.1v lipo batteries, AND it does by the way have an AB mosfet installed. With a 7.4v lipo and conventional batteries he doesn't have this problem, making us wonder if the 11.1v lipos actually cause the gate-signal to be powerful enough to jump across the full auto contact plate. Absolutely mysterious indeed, but he's getting a normal 7.4v lipo now anyways :D

Corleone:

Taking what I've learnt from my Digital Design course it would seem that the voltage is too high and "leaking" over the wires causing a "high" (1) signal to be transmitted instead of a "low" (0). As digital systems must be discrete structures (to the best of my knowledge) you can't have a "half/mixed signal being transmitted". For example, the cutoff for a 5 volt signal for example is 0-2.5v (not inclusive) and is translated as '0' and 2.5-5v is translated to a '1', the reason being why there is a "buffer" is that so it covers voltage drops and spikes.

So it would seem that maybe shielding your friends wires would help. Kind of like shielding on cables today (such as sine Cat5 and old co-ax cables) however it's probably expensive and increases (or is it decrease?) the guage of the wire which you kind of can't have in a tight system such as in an airsoft gun. Otherwise just using lower rated batteries like what you're friend is doing right now is probably a good enough workaround.

Shielding would of course be better, and so would twisting the cables. There's a lot of space inside the P90 for just that. We're running self-made AB mosfets with 16 AWG silicone wire. It takes a lot of space, but there's still room left for twice the stuff we already have. Both the P90 and AUG are beautiful in that way - so much space.
Altho I see your point, the mosfet's not a true digital design. If we had leakage over the wires, the weapon would fire at will if we plugged in the battery. The full-auto issue only occurs once we fire the gun, and actually sometimes it doesn't. When tapping the trigger with less force, it can indeed fire semi, but it's hard to get consistent results. Thus we're both holy convinced that the high voltage, combined with the "selector" assembly of the P90, is the reason for fullauto problems. I will actually make a test by isolating the full auto contact plate.

Sorry for hijacking the thread! I only wanted to make sure you weren't using 11.1 lipos, and had the same problem as we do :)

Try this and see if it works.

Open the battery compartment and remove the plastic plate separating the compartment and the mechbox. Hook up a battery. Press foreward on the end of the mechbox and try firing. If that makes it fire correctly. Put some foam or something on that plate to hold the mechbox slightly foreward.

If this doesn't work...............uh?.......well I don't know......try swearing at it...

FNG; if the gun already fires only in fullauto, then it won't help moving the gearbox even further forward. It would only be helpful if he didn't get it to fire in full auto. It's because of how the selector assembly works.

You can remove the metal rod that pushed on the mechbox and bend it a bit more forward.

You can also clean and push the contacts that are ouside the mechbox further back.

Wouldn't recommend that!

VERY good idea!

You both won the contest!!!
The blades were very far apart from gearbox case.
I´ve push them and everything is running well again...

Thank you all guys!

JR

Please, stop giving advices.

I read all of your posts and I have yet to find one that contains information that is right.

I have had 3 AUGs myself, and I am a gundoc. I have worked on/seen over 20 AUGs over time.

I also had P90s and repared some.

YOUR own P90 issue is caused by two things:
Any spring that shoots under 345 fps will cause V3 and V6 to double feed when used with 11.1v or higher. This is because of the way the cut-off lever works and it's relative position to the sector gear.

The stock motor does not offer enough drag to stop the mechbox right away, and the innertia of both motor's rotor and gears is enough to overcome the resistance of weak springs.

That is the reason why you have double feeding issues.

My last P90 was running on 11.1v 1500mAh 20C LiPo. Never had a feeding issue.

Regarding the problem at hand, yes it can be caused by the transfer rod bending out of shape. Same thing can happen on the P90 because it used the same principle to interact with the trigger. Most of the time, the symptom will be a non-working or intermittent full-auto. But a jam (BB stuck/dropped inside the shell) can also cause the rod to bend backwards.

Seriously? I'm talking exclusively about P90s, and thought that because of the similarities (of the selector assembly) it MIGHT be a similar problem. I have still yet to open an AUG, although this will happen sometime soon.

I give you some simple facts:
- I's not my P90 I was talking about. I would never put an 11.1v lipo on my P90s in the first place...
- There was never an issue about double feeding. Not on that specific gearbox, and not on any of the other 4 I have at home either.
- That one issue causing fullauto with a 11.1v lipo was indeed fullauto, meaning that it did fire until the trigger (altho set in semi) was released.
- Me'n my friend have been been messing around a lot with our gearboxes, including the cut-off lever. The P90 in question was running an AB mosfet and would still fire in fullauto when the trigger was pulled all the way back in semi.
- The exact same mosfet would work flawlessly on all the other, some even identically specced P90s.
- Finally, bending the fullauto contacts on the P90 in question slightly more back, fixed this problem.

So there you have it "doc."

Oh, and why are you trolling me when it turned out one of my (and of course Jimski) advices worked?

Again sorry that the thread would have to move off topic!

Because I read the threads YOU started about two problematic P90s...

YOU stated that one gun was yours and the other was a friend's P90.

And since you just said you never used a 11.1v LiPo in your rifles, how can you know that is causing issues in this specific case.

It is just like in a lot of situations, treating symptoms will not always solve the problem. Bending contacts is a very temporary solution. Mostly because when you heat metals that have been treated, they tend to reshape the way they where when treated. In this case, the original position is causing issues, so just by using the rifle, the contacts will bend back and the issue will show-up again.

That is exactly why there is very little "gundocs" and a lot of tinkerers. JB weld and bending things is not fixing.

Listen man: you have to USE that brain of yours! If not, then please leave the rest of us alone.

First of all. I never started any threads here on ASC yet. Are you talking about posts, and if so, then please at least read them properly! Secondly, please be so kind to refer to them if you ended up not reading them properly after all.

As stated I don't USE 11.1v lipos, but I sure did TEST it on my own P90s and misc gearboxes. I'm seriously puzzled how that didn't come to mind when you read my posts. Oh wait! I'm not :D

Oh and I never stated that I had problems on two P90s. There were two Echo1 P90 gearboxes that had their primary trigger assembly bent, and needed some shaping (not reshaping, shaping. The gearboxes were new). That's china quality for ya, but luckily it's easy to fix such problems. These gearboxes were purchased for hot-swapping according to usage/FPS. After that I mentioned a completely different weapon/gearbox altogether. A Marui P90, that had the lipo-related problem. This was my friends weapon.

And seriously, are you just trying to annoy me, or are you really this stupid?! When you run a mosfet on a gun, there's not nearly enough current passing through the trigger assembly to even slightly upping the temp of it. Yeah unless it's "gun doc" Kos-Mos selfmade aluminum foil trigger contacts...

Can't we all just get along??