G&G MP5 SD6 TOPTECH MAX SERIES (problem + fix)

[marty-demo]

I thought i would share my problem and fix incase someone else might
have the same problem with the G&G max series. so They can fix it too

I'm fairly new to Airsoft and this is my first gun problem and first time opening the gear
box.

the problem

The problem started when the gun would start to seize during games
The seizures would happen when I would pull the trigger all the way back in full auto. If I pulled it half way, it would shoot
Eventually the seizures would happen more frequently. Then my gun stopped working altogether.
Later found out that I blew a fuse .
The blow fuse and seizures were obviously related.
So I did some research and found out the max series come stock with a m140
Spring . From what I heard the motor isn't strong enough for the m140 even if it is a high torque motor. So my gun was working really hard to pull that spring back causing the seizures and eventually blowing a fuse.

I don't know why they would put such strong spring if the motor can't handle it.
Please feel free to correct me if I'm wrong. It might have been a battery issue for all I know.

I was running a 9.6 v

the fix

So I just swapped the spring with the spare m100 that came with my gun and put a new fuse in it ,
The difference is night and day .
The rate of fire and trigger response is way better and feels like a new gun
I also shimmed the gears as well , what a time consuming affair that was !
i can't say it was a perfect shim job but it was good, the gears spun freely
And i noticed a decrease in noise

[MikeWasTaken]

I ran into the same problem, I'm wondering if I should go the other way and update the motor instead of downgrading the spring. I might try your way first thanks

[ARC-74]

Originally Posted by marty-demo

The problem started when the gun would start to seize during games ........So I did some research and found out the max series come stock with a m140 Spring .

Ummm, I might be mistaken, but wouldn't an M140 spring have brought you well above field fps limits?

[Styrak]

....yeah....you didn't chrony the gun when using it in a game?

[marty-demo]

My original assessment was incorrect. Although changing the spring did indeed help enough to give me the illusion that I fixed the problem. Upon further in game field testing, the problem persists
The original test was done poorly. Thinking back now, I didn't pull the trigger down hard enough to get that same trigger pull you would get from an intense in game firefight.
i was only observing the effect of a softer spring.
The spring was actually a 120. Which is why I passed the crony at the game the gun broke
I apologize for a novice interpretation of the data, flimsy research and shorty testing

The problem is still not solved. Although putting in a 100 has helped keep the gun active during a full game. Seizures still occur when trigger is pulled all the way back.
I'm thinking somethings wrong with the trigger assembly? Would a mosfet help?
But a more informed assessment would be best
Also, my recent crony was 260 using. 28 bbs, which seems very low for a m100

[audi_bhoy]

You might want to add 50ish FPS to your result if you're using .28G BBs, keep in mind that the FPS is controlled on .2g, heavier BBs will have slower muzzle velocity, but carry the same amount of energy.

[Styrak]

260 on 0.28g is about 320fps with a 0.20g BB, so it's right where it's supposed to be for an M100 (100m/s or 330ft/s).

[Knoxville450]

Anyone have an idea what it might be? I just bought the same gun and would like to know if its a problem with the power system or not. Mine came with a 2 cell lipo and I dont wanna kill it if there is a big ass spring in it. It does sound like maybe your motor height is not set up correct. Have you tired that? If its not that then I dont know what is wrong sorry.

[marty-demo]

i don't see how the motor height is related
too me it seems like the contacts in the trigger assembly are disengaging when there is full pressure on the trigger , if that is even possible

i recently switched from 9.6v nihm to 7.4 lipo thinking that might work but it didn't

technically to could put a rubber nub of some-type between the trigger and hand grip to prevent the trigger from depressing all the way . but that would only be a work around and you would have a pieces of rubber protruding on your gun

[Knoxville450]

I am thinking that if the motor is jamming somewhere then it might not be set correctly into the gearbox. The fuse had blown before and the motor would really be the only thing drawing current, just make sure you give that a look over.

[lurkingknight]

how would a mosfet fix this issue?

You need to open the gearbox and inspect the function of the trigger switch assembly. The cutoff lever is supposed to pull the shuttle out of the way and open the switch after the sector gear cycles.

If half pulling the trigger works, but fully pulling the trigger doesn't then something is happening out of sequence or there is something preventing the shuttle from doing its thing. Circuit continuity is breaking at a certain point in the trigger pull... investigate the trigger. I'm betting on carbon/burned up trigger contacts.