G&G P90 Semi-auto issue

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TheToxicDuck

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Hello all! 

I'm new to the forum (And to maintaining my own guns) so be nice! :)

I've hot a G&G P90 which has hardly had much gametime and currently the semi-auto is having issues. It struggles to cycle fully when I'm semi auto. Full auto the gun runs fine. When in semi you have to pull the trigger 3-4 times before it finally fires. Each time the gearbox moves a little and until it's back at the starting position.

I've currently got it in bits on my work bench but simply don't understand the trigger mech. It seems to have a two stage trigger. In full auto you can depress the trigger completely and the gun fires. In semi it doesn't allow full depression which means the contacts don't quite touch fully.

Basically, I've got a gun that doesn't fire semi auto reliably and I don't understand how the trigger system works enough to diagnose it.

If I manually connect the two contacts on the gearbox it fires away perfectly! I don't understand how the gun knows it's in semi auto except for the fact that the trigger can't be fully depressed?

Any help would be greatly appreciated! Thanks guys!

Nic

EDIT: I've taken apart the trigger mechanism and now understand the two stage setup. It's just the first stage is very unreliable. Any fixes out there? 

 
Last edited by a moderator:
Hi! When you pull on Semi it connects the internal terminals which you can't really see from outside, once the gearbox has completed one cycle it nudges a lever (the cutoff lever) which as the name suggests stops firing by breaking the connection until you pull Semi again.

You problem (specifically with a P90 / AUG) could be the trigger bar is not being depressed enough to make contact in Semi.

Or you have a problem with the internal trigger contacts.

I assume it fires nice and quickly on auto?

 
Yep nice and quick on full auto. I've just discovered the second contacts used for semi auto. I've squeezed them together in the hopes that it would create a better contact once I pull the trigger but it didn't make much difference. They seem to be very delicate, I'm not surprised they've stopped working.

I don't fully understand how the cutoff lever works. How does it stop it firing twice? Does it push the contact back after a cycle breaking the connection? 

Can you buy new trigger mechanisms/contacts?  

 
Semi is connected with a little dolly that is pushed forwards into the forward contacts. The cam on the inside of the sector gear interacts with the bar on the outside of the box. 1 rotation kicks this bar. In turn that kick lifts the back side of the dolly over the trigger, and a spring pulls the dolly back to a ready to fire position. Release the trigger and it moves back and catches the dolly again ready for the next shot.

Make sure the spring is in place, The dolly is clean and free from lube (it only wants a very light spray of silicone). Grit and dirt in the dolly and and seating can stop it working, Also if the step on the bottom of the dolly is worn it will stop it been pushed.

The bar needs to move correctly and smoothly. It should kick up at the contacts for each box rotation. If it's sticking up then you need to look at that. It may also be worn or bent.

https://www.fire-support.co.uk/product/gg-p90-pdw-switch-assembly

https://www.fire-support.co.uk/product/gg-p90-pdw-cut-off-lever

 
Last edited by a moderator:
I have a G&G P90 which i got second hand and it also had issues with the semi auto - i played around for a long time , cleaning the dolly and contacts etc. even replacing the whole switch unit but nothing really fixed the issue-  what i found was that the dolly did not make good enough contact to complete one full cycle before the cut off level flipped the dolly off, I followed a mod which i can't find sorry which basically means you make the metal contact on the dolly a bit longer by adding some solider to it, this allows the semi switch to make contact quicker before the cut off lever flips it off, quite simple to do and this improved the trigger a lot but did not completely remove the issue so in the end i fitted a Gate Nano ABB mosfet - now works flawless 

 
If that is a flaw in the G&G P90 and it turns out to be the OPs problem too then I'd suggest fitting a Lonex contact/trigger set or similar and or fit a MOSFET.

I actually did some upgrade testing to a mates TM P90 yesterday that shows how much improvement you can get from a MOSFET alone*....

STOCK on 7.4 30c LiPo
275 fps
16 rps

STOCK with picoAAB
275 fps
19 rps

And trigger response went through the roof :D

*Fet was installed with 14awg / Alpha wire

 
I fitted the replacement G&G trigger and the gun now operates correctly. 

@Davegolf: do you have a link to the lonex trigger?  

 
Davegolf said:
If that is a flaw in the G&G P90 and it turns out to be the OPs problem too then I'd suggest fitting a Lonex contact/trigger set or similar and or fit a MOSFET.

 

 I actually did some upgrade testing to a mates TM P90 yesterday that shows how much improvement you can get from a MOSFET alone*....

 

STOCK on 7.4 30c LiPo
275 fps
16 rps

STOCK with picoAAB
275 fps
19 rps

And trigger response went through the roof  :D

*Fet was installed with 14awg / Alpha wire
Click to expand...
Click to shrink...




Any videos on how to install one of these?

I have the same problem with my JG P98-1 and I'd like to use it at a semi-only CQB site.

 
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