Gate Merf 3.2 not working correctly? F2000 semi-auto trigger not working

[RostokMcSpoons]

I've taken it apart again and checked:
The plastic trunnion was correctly located into the gearbox shell.

The dolly seems to move freely back and forth against the spring pressure. 

My pic shows it elevated but that's it's natural backwards position.

Pulling the trigger moves it forwards and slightly upwards.

I don't know, but it all looks the same to me as it's done before (when it worked, pre-MOSFET)

I'll ask the Gate tech support if they've seen anything similar

Edit: Set up a support ticket with Gate this morning, let's see if they have any ideas.   I referenced this thread, so y'all be on your best behaviour, y'hear!

 

[RostokMcSpoons]

(Probably 'bad form' to bump my own thread after I replied last, but 'what the heck')

Stripped the gearbox down to take a close look at the trigger contacts. and check alignment of everything.  The contacts on the dolly looked like they were touching the front contacts on one side, so I widened the gap slightly so only when the dolly moved forward would it contact either of the sprung arms... somewhat like this pic nicked off t'web...

View attachment 85078

(actually the main contact goes much further forward between the two arms when the trigger is pulled)

I thought that might fix it.  

It didn't.  

I've just tried setting the FET to do SEMI/SEMI as the firing options, but the darned thing only does SEMI/BURST so I can't use it on site unless I sort it
Having it on SEMI/BURST, it does do the three rounds properly, but can still do it even with the full-auto contacts blocked with a piece of paper.

@ak2m4 is there any mileage in ordering a replacement trigger unit, do you think?

I'm also still waiting on a proper reply from Gate, though they've acknowledged my ticket has been raised.

Edit: They just did. 
First step is they want me to solder the signal wires directly to the front contacts. 
"It seams that the problem is with the trigger contacts. F2000 is a rare replica and honestly we do not have one in our armory but we will try to help you as much as we can. In first step we would recommend to desolder these wires on the photo and then solder only signal wires from Merf directly to the gearbox trigger contacts and check if the semi-fire mode works as it should."
 I could point out that's electrically no different but I guess I'll just go ahead and do it anyway.  Then I'll ask them if they have a Steyr AUG as that's the same setup isn't it?

 

[Adolf Hamster]

so it's still firing bursts on semi?

the mosfet should only run while it's getting continuity between the 2 signal wires, it relies on the gun to shut off. if it keeps getting signal it thinks it's just being run in auto.

the paper will prevent the auto contacts from triggering, which is easy to accidentally trip when testing on the bench (the g&g v6 has the same issue, albeit with the "trigger" being mounted in a different place)

so the gun isn't shutting off, one thing to check- do you have ab enabled? if you do try turning it off as that can cause some weird issues (took me years to figure out thats what the issue with mine was).

the other thing, which is what you've been looking at, is that the contacts don't engage too early, in a position where the COL isn't able to trip them when it fires.

do you need it semi only for DMR power? if so then one way would be to remove the connection to the auto contacts

 

[RostokMcSpoons]

so it's still firing bursts on semi?

the mosfet should only run while it's getting continuity between the 2 signal wires, it relies on the gun to shut off. if it keeps getting signal it thinks it's just being run in auto.

the paper will prevent the auto contacts from triggering, which is easy to accidentally trip when testing on the bench (the g&g v6 has the same issue, albeit with the "trigger" being mounted in a different place)

so the gun isn't shutting off, one thing to check- do you have ab enabled? if you do try turning it off as that can cause some weird issues (took me years to figure out thats what the issue with mine was).

the other thing, which is what you've been looking at, is that the contacts don't engage too early, in a position where the COL isn't able to trip them when it fires.

do you need it semi only for DMR power? if so then one way would be to remove the connection to the auto contacts

Yeah, still bursting on semi.

I haven't seen any method to switch off AB on the Merf.   I think I should have bought the Perun just because it has more tweakability

I haven't really worked out how the COL works, in terms of interaction with the other components, I'll need to need to find an explanatory video later.   But I had checked it moved ok and it didn't look like any bits had broken off it.

(Remember, I did have a problem where the piston broke at the back, when the piston head came  undone and ended up half way down the spring, so there's definitely potential for something having gotten buggered.  But of course that happened after I had the first instances of semi not working.
Original piston put back in and seems fine so far.
I've also got a gouged bushing under the bevel gear that I'll need to replace shortly.  I redid the shimming in the gearbox last night and discovered that problem, so I'll order some new 7mm bushings to sort it.)

This isn't a DMR build, it's just the site has some CQB tented areas where we can only go to Semi, so even bursts would make me unpopular

Edit:   Hmmm I just searched on F2000 COL, and apart from the fact it's considered a 'bad design' and an 'achilles heel', at least with the G&G version, I also found mention of the COL not engaging with the sector gear due to shimming.
I have had to shim the sector quite a bit as there was a lot of play initially... maybe I need to shim the COL as well?

 

[Adolf Hamster]

Yeah, still bursting on semi.

I haven't seen any method to switch off AB on the Merf.   I think I should have bought the Perun just because it has more tweakability

hmm, i thought you could turn it off on the merf, compared to say the nanoaab (picoaab? something like that) where it's permanent.

that could well be a potential candidate then, i certainly wouldn't be ruling it out as causing this as i've seen more than enough guns go from chugging all day long to barely scrape a few shots thanks to ab.

I haven't really worked out how the COL works, in terms of interaction with the other components, I'll need to need to find an explanatory video later.   But I had checked it moved ok and it didn't look like any bits had broken off it.

pinching this pic from earlier in the thread:

View attachment 85005

the trigger will push the trolley forwards, the col kicks it up, the return spring pulls it backwards over the top of the trigger (well, the trigger extension) until it's reset.

come to think of it, looking at that picture, is that spring (the one just above the arrow tip) getting pinched? kinda looks it? that should be the spring that pulls the trolley back.

(Remember, I did have a problem where the piston broke at the back, when the piston head came  undone and ended up half way down the spring, so there's definitely potential for something having gotten buggered.  But of course that happened after I had the first instances of semi not working.
Original piston put back in and seems fine so far.
I've also got a gouged bushing under the bevel gear that I'll need to replace shortly.  I redid the shimming in the gearbox last night and discovered that problem, so I'll order some new 7mm bushings to sort it.)

that shouldn't be affecting it as long as it's able to do a complete cycle. only real issues you'd see is either the wrong type or worn out col (unlikely in this case- i'm assuming those are original parts and not that old) or the sector gear shimmed way too high (again unlikely, it's pretty tricky to go that extreme)

 

[RostokMcSpoons]

The spring does look a bit awry in that previous pic, but it looks ok to me now...

View attachment 85082

The sector gear has 2 or 3 shims underneath and 1 or 2 on the top it so yeah it doesn't seem that likely to have got it out of position.

Another reddit thread suggested going back to 7.4v, so I've just tried that.   Same thing.
So pretty sure there's a mechanical issue hidden in this thing somewhere!

When lunchtime arrives, and I can spend some quality time on this, I'll change over the contacts (which I don't expect to fix it) and then record some video. It'll give me a reason to try 'Slow Motion' mode on my phone camera for the first time ever

And if I get really, really, really stuck with this I'll try to put it all back to pre-MOSFET mode to see what happens then. 

 

[RostokMcSpoons]

I bodged it back to pre-MOSFET wiring, and it still does it.  So the there's definitely something wrong with the trigger / COL assembly.

I've got some slo-mo video too... very instructional!  I can see the contact dolly moving up and breaking contact on the semi shots, and shuttling back and forward whilst flat on the burst/full shots.
I'll edit them down and upload them to YT shortly.

The interesting thing to note is for my first video I used a thicker piece of card to block the full-auto contacts, and that seemed to help it stay semi-auto.  When I recorded the second I just used electrical tape ... and eventually it does the burst/full. 

In any setup I find that once it's started to do it, it keeps on doing it.  Maybe something is sticking? I'm using silicon gear lube from AK2M4 sparingly on the moving parts - but perhaps it's too viscous?  Should I get some silicon spray in there to thin it down?

Edit: Decided the one video was enough: the first couple of shots go on semi correctly, it's all downhill from there...
 

Epic slo-mo sounds

Edit2: Ah sod it, I bought a replacement Rocket trigger unit and COL from @ak2m4 ... let's see if those will help at all.

 

[Adolf Hamster]

hmm, that's very definitely the col failing to lift the trolley.

wonder is the col worn? i know i said i didn't think it had earlier but i'm starting to doubt myself on that front. looks like it's in constant engagement, usually when you fire in auto it's lifted out of engagement to stop it wearing out as quickly.

other thing might be worth trying, but if you remove the auto contacts (as in physically remove them, not just isolate the wiring) and see if the extra clearance to pull the trigger back lets it trip properly?

 

[RostokMcSpoons]

The COL shouldn't be worn, the gun was new at Xmas, it's had a less than a couple of thousand BBs through it.
I have taken it all apart a few times though, and as I'm still "low on the foothills of Experience Mountain", I may have buggered it up somewhere along the line.  The fact it does work quite often before deciding it'd rather crap over everything is odd.  A bit of heat in the system makes it go wrong?  Maybe a tiny bit of expansion makes a 0.01mm difference somewhere and that's enough to b0rk it.
 
However, I've now seen enough other people complaining about similar issues with their F2K's (though mostly G&G which is very differently built) that maybe it's something that can just easily occur.

Hopefully the Rocket after-market parts will get it back on track, but I will try your suggestion tonight in the meantime.

 

[ak2m4]

@RostokMcSpoons posting it out this afternoon for you Ross, hopefully it works out.  Fingers crossed.

 

[Lozart]

If the new COL doesn't fix it, you could always try one of these: https://www.srairsoft.com/shop/f2000-m-trigger-gen-4

 

[RostokMcSpoons]

If the new COL doesn't fix it, you could always try one of these: https://www.srairsoft.com/shop/f2000-m-trigger-gen-4

I saw that!  But...
Compatible only with G&G F2000’s without an ETU (pre-2019)

I'm not sure if that means 'only G&G' or really 'Only V3s without an ETU'.  
Given the G&G doesn't use a standard v3 gearbox, I'd have to ask them first.

@RostokMcSpoons posting it out this afternoon for you Ross, hopefully it works out.  Fingers crossed.

Cheers    It'll be great to have my pew-pew pew, or pew-pew-pew on demand

 

[Adolf Hamster]

The COL shouldn't be worn, the gun was new at Xmas, it's had a less than a couple of thousand BBs through it.

that was my initial feeling, but the issue is that whereas in a normal gun the COL gets lifted free when used in auto that's not happening. although i've had plenty of v3 boxes firing a lot of rounds in semi auto to suggest they shouldn't wear out that quickly.

I have taken it all apart a few times though, and as I'm still "low on the foothills of Experience Mountain", I may have buggered it up somewhere along the line.  The fact it does work quite often before deciding it'd rather crap over everything is odd.  A bit of heat in the system makes it go wrong?  Maybe a tiny bit of expansion makes a 0.01mm difference somewhere and that's enough to b0rk it.

the thing i'm thinking is it's essentially half-pulling the trigger in normal use, compared to how it'd be in its normal ak role which is what the trigger/trolley/col was originally designed around.

However, I've now seen enough other people complaining about similar issues with their F2K's (though mostly G&G which is very differently built) that maybe it's something that can just easily occur.

i must admit, i'm getting a lot of deja vu here. col's wearing out quicker than you'd expect (granted on the g&g it's as much due to the weird leverage it's being put through) and being just a bit finnicky on semi.

Hopefully the Rocket after-market parts will get it back on track, but I will try your suggestion tonight in the meantime.

fingers crossed, if not there are still some cards left to play.

If the new COL doesn't fix it, you could always try one of these: https://www.srairsoft.com/shop/f2000-m-trigger-gen-4

is an interesting solution, but it's for the g&g non mosfet version, although granted i wish it had been a thing when i was going through this

 

[RostokMcSpoons]

I've looked again at the manual for the Merf. 
I think if in the worst case I can't fix this, I change it to SEMI/BURST...  and then tweak the burst timer down to its minimum, and set the RoF reduction to its maximum and so if/when it goes wrong it fires only a one - or at worst two - shots and I can then get away with using it at my site  
It'll be an interesting experiment for tonight anyway!
 

 

[RostokMcSpoons]

other thing might be worth trying, but if you remove the auto contacts (as in physically remove them, not just isolate the wiring) and see if the extra clearance to pull the trigger back lets it trip properly?

Just took the gearbox apart again, moved one of the thicker shims on the sector gear from the bottom to the top, in the hope it would engage better with the COL.

And tried your thing of removing the trigger contacts.

As per usual, it worked fine on the first couple of shots, where I was squeezing the trigger gently, but as soon as I got slightly medieval on its ass and tried a more realistic trigger pull, "rat-a-tat-a-tat"

I'm going to re-set the wiring to use the MOSFET again, to try my cunning plan, and then it's down to those alternative parts.   Confidence is not very high

 

[Adolf Hamster]

As per usual, it worked fine on the first couple of shots, where I was squeezing the trigger gently, but as soon as I got slightly medieval on its ass and tried a more realistic trigger pull, "rat-a-tat-a-tat"

hmm, i was expecting the opposite- no dice unless you operate the trigger "in a soldierly fashion"

I'm going to re-set the wiring to use the MOSFET again, to try my cunning plan, and then it's down to those alternative parts.   Confidence is not very high

we haven't quite exhausted all the options, although the final option i'm certain will work it's not particularly appealing.

 

[RostokMcSpoons]

My cunning plan of programming the 'fet has resulted in a gun which mostly fires semi, but throws in a double-tap every four or five shots.
I expect I could get away with that, if I had to. 

But let's face it: the trigger action is bad enough with F2000's (and maybe bullpups in general) that you don't want to spend the whole game yanking away on the damned thing!

Plus I upgraded this gun to enjoy some high RoF antics (not full wanker-mode, obvs)

I must say I'm disappointed that a Cyma-built gun has turned out to be quite this fragile. 

Or perhaps my upgrade attempts have been a bit too ham-fisted. 

Edit:
Is there any chance the cam on the bottom of the sector gear could be the problem?  Should I buy a new gear too?

 

[Adolf Hamster]

My cunning plan of programming the 'fet has resulted in a gun which mostly fires semi, but throws in a double-tap every four or five shots.
I expect I could get away with that, if I had to. 

But let's face it: the trigger action is bad enough with F2000's (and maybe bullpups in general) that you don't want to spend the whole game yanking away on the damned thing!

Plus I upgraded this gun to enjoy some high RoF antics (not full wanker-mode, obvs)

don't blame ye, 90% of the firing i did with mine was in bursts outdoors, admittedly i lean towards semi in other guns, where the trigger isn't made by black and decker.....

I must say I'm disappointed that a Cyma-built gun has turned out to be quite this fragile. 

Or perhaps my upgrade attempts have been a bit too ham-fisted. 

it's one of the issues with the more obscure platforms is getting weird niggles like this, if it's any consolation the original g&g was every bit as bad but throw in lack of available spares for the trigger/col and lacking the end-game option.

Is there any chance the cam on the bottom of the sector gear could be the problem?  Should I buy a new gear too?

unlikely, out of the 2 the col is the thing that'll wear. don't think i've ever seen a sector cam actually wear out (as opposed to the default shape not matching a given col for a given box)

 

[Iceni]

Sorry been at work

Yeah definitely the COL/Dolly interaction that's failing. Glad it's not the Mosfet.

I'd replace the unit for standard V3 parts. The SHS/RA parts should be fine. But to be sure I'd do the COL and front contacts. That way you rule out wear, and warping on the COL as well. 

If I had the time I'd say pop over at the weekend and I'd fit it all for you, but we are in the final week before the British retail consortium audit at work, and panic mode in the engineering management is kicking in.

 

[RostokMcSpoons]

That's a very generous offer Iceni, but hopefully I'll be able to jam all the parts in and make it work.

I've got three different hammers, how could it possibly fail?

I rather wish it was the MOSFET, that'd just be a warranty replacement, or swapping for a Perun, or even just reverting to the old wiring, rather than this mystery box stuff!

Oh, I've got a replacement COL on order too.