Odd TM FAMAS problem I can't sort out

[CDN_Stalker]

Must be FAMAS related, so here I am.

Yes, have had one of these ugly things in my hands for a while, here's the history:

It belongs to a teammate, he had it in the hands of the previous local gun tech for almost two years, owner got it back and gave it to me to check out. Aside from missing the trigger bar linkage (DOH!!!) and a pile of screws, everything seemed to be there. I checked it all out, got it working, then came across a weird problem: every time you pulled the trigger on full auto, it'd fire no problem. Then you go to pull the trigger again........... nothing, until you release the anti-reversal latch. Then same thing every time.

Ok, I let the owner know about the missing parts and the problem, and left it at that. A year later the owner gives me a NEW trigger bar linkage, I tried cycling the mechbox again and the piston would seize back every trigger pull. Odd, never happened before. No matter what I did the piston would always jam up. Turned out the piston head was grabbing the beginning of the piston rails and jamming into the sector gear.

Enter the Dremel!!

Ok, I got it cycling fine now (would unwind every few bursts, I swapped out the two lobe bevel gear for a four lobe bevel type, fixed that problem), but this time I can get a few to a half dozen bursts out of it, then the stopping occurs and have to hit the anti-reversal latch button to get it shooting again. What is up with this damned thing?!?!

Please, I never ask for much here on ASC, but can someone help me make my workbench pretty again by solving this so I can get this FAMAS thing out of my home asap? It's a truly ugly gun and I want it GONE!!!!

[Sha Do]

Originally Posted by CDN_Stalker

Must be FAMAS related, so here I am.
.................
Please, I never ask for much here on ASC, but can someone help me make my workbench pretty again by solving this so I can get this FAMAS thing out of my home asap? It's a truly ugly gun and I want it GONE!!!!

Wish I could help you out bro, but I never touch the stuff.....and everyone I know that had one of these...notice I said had...
Seriously though, I have never had to trouble shoot this kind of problem, and so I shall do some homework and chat with some retired airsoft techs to see what we can figure out.

SHA DO

[The Saint]

Maybe there are non-version 1 compatible parts mixed in there?

[mcguyver]

Dead spot on the motor? This can cause mid-cycle stoppages, and be quite intermittant, depending on when you stop impulse to the motor, whether it's on the dead spot or not.

You can see this on the bench of you remove the motor from the gun and try lots of start/stop cycles. It will eventually show up, but it's a little harder to spot as the intertia of the rotor will let the dead spot pass by alot more often than if you have the counter-torque of the spring bringing rotor inertia to a quick halt.

[HaZarD SFD]

How much was it unwinding on that 2 bevel? if a bit or some then its fine.. .. imho its normal. Unless its unwinding totally.. I would keep that 2 lobe in there.

[CDN_Stalker]

Originally Posted by mcguyver

Dead spot on the motor? This can cause mid-cycle stoppages, and be quite intermittant, depending on when you stop impulse to the motor, whether it's on the dead spot or not.

You can see this on the bench of you remove the motor from the gun and try lots of start/stop cycles. It will eventually show up, but it's a little harder to spot as the intertia of the rotor will let the dead spot pass by alot more often than if you have the counter-torque of the spring bringing rotor inertia to a quick halt.

Hmm, is one thing I hadn't considered (yet had found that problem before with Hazard's G&G M14, had an upgraded spring and he shot it a lot on semi, ended up burning a coil on the motor........... I tried just the motor outside of the mechbox, woud spin a few times then stop, had to rotate the pinion gear a couple 'notches', would come back to life until the dead spot hit again........ he replaced it with an EG1000 short motor, problem never happened after that. Was last summer BTW. A couple weeks ago he was here and I dug his old motor out of the garbage, showed him the burnt coil section, he said "Holy FUCK!!!". Will check that out, thanks. Makes sense actually since releasing the anti-reversal latch let's the gears unwind to rest, and the attached motor get's spun too.

Gun is stock except for metal bushings and upgraded spring. Problem happened with two lobe bevel gear before, as well as the unwinding on occasion, but unwinding stopped for good with the four lobe bevel gear.

[Amos]

Stalker, I've got an old EG560 (FAMAS type I believe)

It's yours for 5 + shipping :P

Could possibly fix the problem..

[CDN_Stalker]

Originally Posted by Amos

Stalker, I've got an old EG560 (FAMAS type I believe)

It's yours for 5 + shipping :P

Could possibly fix the problem..

Very cool, I'll take you up on that Wednesday (payday). If it isn't the problem I at least have a spare. If you accept EMT, I'll fire off $15 to you then, give me your prefered email address.