Problems on semi!!!

[bobotea]

Hi all

I received my Jing Gong M4 CQB today from AA. I charged the battery up only to find that when I shoot on semi it randomly goes into a auto burst only for a few seconds. If anyone has had this problem before or knows what’s going down, help would be appreciated.


Thanks

[dodger_me]

take it to your gundoc, can range from trigger switch to Cutoff switch or as easy as a shimjob

[bobotea]

thanks i will have to open up my gearbox this weekend and see wutsup

[m102404]

If you're comfortable with working on a V2 you'll be fine. The last two JG mechboxes that I've troubleshooting had similar issues.

One mechbox, when set on semi, would fire full auto if you slowly pulled the trigger back and then stop shooting when you completed the full trigger pull (kind of like a reverse AUG trigger).

The other mechbox, when set on semi, would fire full auto with a complete trigger pull if you held the trigger back, and then on the next trigger pull would fire one shot, then full, then semi, etc...

On the first mechbox, the part of the cutoff lever that interfaces with the oval nub on the bottom of the sector gear was worn and the "tooth" was severly rounded over. Swapping it out to a new cut-off lever fixed that.

On the other mechbox, the lever looked ok, the but switch assembly was a bit funky. Taking all the internals out of the mechbox, then carefully reassembling them seemed to fix it. But the "action" of the lever disconnecting the switch block is very stiff compared to a number of other mechboxes I've worked on.

So...take a close look at the cutoff lever, switch assembly and sector gear. Before you take it all apart, check the obvious stuff like shorts in the wiring and the little spring that pushes against the cutoff lever.

Best of luck!

Tys

[bobotea]

Originally Posted by m102404

If you're comfortable with working on a V2 you'll be fine. The last two JG mechboxes that I've troubleshooting had similar issues.

One mechbox, when set on semi, would fire full auto if you slowly pulled the trigger back and then stop shooting when you completed the full trigger pull (kind of like a reverse AUG trigger).

The other mechbox, when set on semi, would fire full auto with a complete trigger pull if you held the trigger back, and then on the next trigger pull would fire one shot, then full, then semi, etc...

On the first mechbox, the part of the cutoff lever that interfaces with the oval nub on the bottom of the sector gear was worn and the "tooth" was severly rounded over. Swapping it out to a new cut-off lever fixed that.

On the other mechbox, the lever looked ok, the but switch assembly was a bit funky. Taking all the internals out of the mechbox, then carefully reassembling them seemed to fix it. But the "action" of the lever disconnecting the switch block is very stiff compared to a number of other mechboxes I've worked on.

So...take a close look at the cutoff lever, switch assembly and sector gear. Before you take it all apart, check the obvious stuff like shorts in the wiring and the little spring that pushes against the cutoff lever.

Best of luck!

Tys

Hey thanks for all the help. I opened up my gear box (for the first time)... and replaced the sector gear which looked warn (the tooth that interacted with the sector gear was totally warn off so i replaced it with a systema v2 cutoff lever). But when I reassembled it and shot it, it still shot in auto busts when in semi auto :banghead: . since I am a noob at doing this it took me three tries to get the shimming right and that kind of stuff correct. Now I have another problem I adjusted the motor to high so now the motor head is banged up a little and makes a really loud screeching noise even when I adjust perfectly. Well every one has to start some where...at least I know how it all works now

[Caped_crusadar]

the noise is beacuse you didnt get it shimmed right, go to this site, it is wonderful, look under the shimming guide

http://pageproducer.arczip.com/daedalus03/workshop.html

[pizzainthemorning]

The noise can actually also be your motor positioning. On my own JG M4 and a friend's TM M16 the motor was very touchy, you had to get it in just right so that it wouldn't either lock up or get too screechy. It was incredibly stiff in my M4. Ensure that it slides nicely within your handle, and try maybe adjusting the hex screw on the bottom if you have to.

And I've also had the same problem with my JG and had the same suggestions as above. I haven't had a chance to replace anything yet, but if I do, and it works I'll PM you. Also, give me a shout if anything you do fixes it.

Alex