AU3G won´t fire "semi"

[jotaerre]

Hi forum users!

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



Thank you in advance!

[Rock 'N' Roll Outlaw]

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.

[SHÖCK]

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.

[jotaerre]

Originally Posted by Rock 'N' Roll Outlaw

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.

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

[jotaerre]

Originally Posted by SHÖCK

If it doesn't, then you cut-off lever is worn out and needs to be replaced.

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


JR

[Jimski]

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.

[SHÖCK]

Originally Posted by jotaerre

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


JR

http://shop.ehobbyasia.com/guarder-l...-lever-v2.html

[Crunchmeister]

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.

[Corleone]

Originally Posted by Jimski

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'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

[L473ncy]

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.

[Corleone]

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

[FNG]

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...

[Corleone]

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.

[Kos-Mos]

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.

[Corleone]

Originally Posted by Kos-Mos

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

Wouldn't recommend that!

Originally Posted by Kos-Mos

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

VERY good idea!