Very strange G36 pistol grip electrical glitch
 

Well, i have been trying sort this one out for a few days now. I recently re-wired my JG G36. When i installed my new switch assembly, there were a few glitches, but i got it all worked out.

Halfway though a game last Tuesday it stopped working, i assumed that th battery had died, and as i only brought one with me that day, used my GBB for the rest of the night.

When i got home, i tried charging the battery, with no luck.

So, heres my problem. with the mechbox removed from the pistol grip/lower reciver, it works fine. When i put it back in, it doesn't. My first guess was that there were some wired getting pinched on odd angles, so i tried moving them around, with no avail. Finally, i got fed up, removed the base-plate from the bottom of the pistol grip and tried to connect the motor through the bottom, so no wires were running through the grip. Still didn't work.

This baffles me, and all of what i thought i knew about electronics, anyone have any ideas what might be up? I can post pics/vidoes if that would help.

Thanks guys,
-Ben

Is the battery on your G36 connected through an addition length of wire with the fuse on it? On the CA36, this was a piece of wire about 6" long that plugged into the wires from the mechbox on one end and the battery on the other.

You mean the length of wire that runs through the barrel assembly?

No, I am plugging the battery directly into the mechbox.

Bump? Anyone?

Sorry for the early bump but i really need to get this working by the end of the weekend...

Take an ohm meter and find out the source of your problem. Sorry but we cant do that over the forums. They are a good investment and usually a cheap one goes for 20 bucks at home depot

Check for continuity:
Red wire:
-Put one probe of a VOM (Volt-Ohm-Milliameter) on the red wire of battery connector, and the other one the motor terminal.
-Press the trigger, there should be a continuity.
-If not, there's a problem.

Black wire:
-Same as above, only thing is you don't have to have to press the trigger to check its continuity.

You might also want to inspect the wires for strip along its length. It could also be shorted on the gearbox, check wirings on switch assembly.

Hmm, okay, ill pick up a VOM, i think my dad might have one somewhere...

As for the wiring and trigger contacts? They all look good to me...

I had same issue then replaced the trigger assembly
 

I checked all wiring and it turned out to be a dirty little connector inside the trigger assembly.

It can also be the wires getting pinched in the handle as you reload. Make sure the wires are in the correct grooves in the handle above the motor. There are two small gaps for the wire to run through.

I hope this helps too.

Yeah, i see those grooves. The reason i dont think that there is an issue with the connectors is that when the mechbox is out of the lower, it works just fine. When i slide it back in, there is a definate point where it stops working, about right as the trigger passes through its hole in the reciver. When i move the mechbox back up an inch, still half in the lower, it works fine.

Same thing, even with it connected through the botom of the pistol grip.

Gah!

You can have a partially broken wire. Basically, it would be the insulation that hold the connection. When you fit the mechbox in the receiver, the insulation moves and disconnect the wires.

Check for a weak/cold solder too. Sometimes they will "stick" to the metal tab, but no electric connection is present. This can be detected by gently moving the wires close to the solder point. If it detaches, there is the issue. Also, cold solders are usually a dull white/pale gray instead of shiny.

Hmm, okay, ill double check the sodder points. I'm thinking that the most likely spot for there to be an issue is with the motor connectors.

UPDATE:


This... is... so... wierd.


I completly removed my entire motor cage from the botom of my gun.

So, I am just firing the motor, but nothing inside the gearbox actually moves when i pull the trigger. When the motor is removed, and placed about a foot away from the lower reciver and the rest of the mechbox, it fires perfectly fine. When i start to slide the top half of the mechbox into the lower reciver, while still holding the trigger, the motor just keeps spinning. When i get the mechbox about 80% into the grip, the motor suddently stops, even though there is no change in the wiring. move the mechbox back up a few centimeters and the motor kicks back in.

I'll post pics in a second.

Man... im totally baffled.

Sounds like broken connection at or after the motor electrical points...try flexing the wires going to it...see if you can cause it OUT of the grip

i think your misunderstanding me.

At this point, the motor isnt connected to the mechbox, it is out of the grip

No wires at all are inside the grip right now! in fact, no wiring or connectors are in contact with the lower reciver at all

Ah yes....so loose connections at the trigger switch then? Leave it out of the lower, with the switch held on, and flex the electrical wires to see when the motor stops...sounds like there is a flexed break in the external wires...or flex AT the trigger switch is causing an interruption.

Hmm, dont think so, brand new trigger contacts.

Also, on the G36, the trigger contacts arn't touched by the lower. When i slide on the lower, nothing touch the trigger contacts at all...

I just took a few photos, ill upload them shortly

this happens on JG G36s all the time. I had it happen on 2 I worked on.

I replaced the wiring harness because the wires were getting pinched by the grip. You couldn't tell from outside but the actual wires were broken or suffering metal fatigue inside the insulation. I also shaved some plastic away from behind the trigger because I found when you put in the metal pin that holds the mechbox in, sometimes it holds it at the wrong angle and the trigger doesn't go far back enough to get the trigger assembly to work. It also sounds like your trigger assembly is worn out, that's happened on my first JG G36. I replaced that too. The piece of plastic that slides forward to engage the contacts kept slipping/popping off the trigger lever.

PICS!

First picture: Mechbox out of the lower reciver, when i pull the trigger, the motor spins fine

http://i518.photobucket.com/albums/u...g?t=1247367912

Second picture: As i start to slide the mechbox into the lower while still holding the trigger, the motor keeps spinning

http://i518.photobucket.com/albums/u...g?t=1247367880

Third picture: As the mechbox gets about 80% into the lower, the motor suddenly stops, even though none of the wiring or contacts are touched by anything

http://i518.photobucket.com/albums/u...g?t=1247367992

This is so wierd...

Already replaced the wiring harness, in fact, already replace all the wiring and connectors in the entire gun.

ok...assuming you have confirmed that moving none of the external wires (yes I know they are not touched by anything...still best to confirm this) breaks the electrical connection could it be that when the lower and fire selector switch engages that the trigger contacts are disengaged mechanically?

Does adjusting the selector switch affect the issue? Give it a try.

Test: leave lower off and move the fire selector interface on the mechbox
Test2: engage the lower at 80% (as pictured) and adjust the switch..Any effect?

The only other thing I can think of is that the lower is squeezing the mechbox and affecting the electrical contacts in the trigger switch assembly.

Test: squeeze the mechbox and try and cause the break. (Doubt this)

Already tried ajusting the selector, nothing....


Squeeze the mechbox? im not exactly sure what your trying to say, but i tried what i think you mean, no change.

hold your battery at step 3 (http://i518.photobucket.com/albums/u...g?t=1247367992) and see if it's getting hot, if it is, there is a short somewhere (no matter how improbable it might seem). I had a short once where the two wires go into the trigger assembly were and the motor didn't respond but the battery and wiring got hot.

It's not so wierd to me to see this issue since I have seen it happen on 2 JG G36s. It is quite a strange one though but it does happen. I can only tell you on both cases, I took apart the mechboxes for upgrades, put them back together with different wiring harnesses and trigger assemblies (I had that same low resistance set you seem to have on my JG G36 but I moved it to a CA and put in a stock wiring harness and trigger assembly back into the JG). Then all my guns worked.

The only logical things are that something is breaking continuity at picture 3. It could be the fire selector gears squeezing the body or causing some sort of wierd short or ground. It could be that the trigger is not the right position since I know you have to push it forward slightly to get it into the lower.

Already checked for a short, and the battery is staying very cold...

Unfortunatly, i can't but the stock wiring assembly back in, as it is gone >.>

Take the fire selector gear assembly out of the lower, that should be everything that is metal inside the lower grip.

I already took the small rod that connects the two sides of the fire selector out.

How do i remove the two gears? is there a screw somewhere? or do i just pry them out?

Okay, so i just took out the fire-selector half gear, so there is nothing metal inside the lower reciver.

Didn't change anything >.> Still cuts out when the mechbox is about 90% into the lower reciver

UPDATE:

Well... this really makes no sense remotly to me... but...gah!

so, at this point i have removed the selector half gears from inside of the lower reciver. When i place the mechbox back in (While still holding the trigger) the motor keeps spinning. I can get the mechbox all the way, back seated well inter the reciver. But! when i stop firing, i cant get it to fire again untill i take the mechbox back out of the lower....


my brain hurt >.>

Have you taken the trigger unit out and inspected it?
I have seen problems before where one of the screws compressed part of the trigger pushing it in slightly. This is the one screw that holds side plate on , if the screw is over tightened it will push on the trigger housing. When the mech box is out of the gun it works fine but when its assembled it fails to function.

Yeap, checked all the trigger contacts.

Its strange, i installed a whole new wiring/switch assembly. Worked fine for about a week, now this >.>

Ill go chack that screw on the side plate now...

Tried loosening, adusting, and completly removing the side plate. Didn't make a differance

SOLVED!!! :D :D :D :D!

Turned out that the amount of pressure to activate the swich on my new KA wiring harness was more then on the old stock JG harness.

Solution? File back a bit of the back end of the trigger hole on the lower reciver until you can get it to connect.

Now.... if only i could solve my wierd airseal issue... but thats a whole other can of worms :P

About your airseal issue...

Check the piston/cylinder/nozzle assembly for leaks, if there is none, your problem is the same as in my old JG.


Shave about 1/2 mm from the REAR face of the little nubs on your hop-up unit.

The two little tabs that keep the hop-up unit from springing out when you remove the mechbox.

Mine had some burs/moldings that prevented it from sitting far enough back...

Ill check that.

Actually, the hop-up isn't stock, Its a Pro-win CNC hop-up chamber, with a Gaurder clear rubber. Also, the front barrel assembly that the hop-up slides into has already been replaced with a TM barrel assembly

Haha, that's what I said in http://www.airsoftcanada.com/showpos...4&postcount=17 :P Grind away at the plastic behind the trigger.

If you have done a compression test on your cylinder and there is no airleak there, the airseal problem is caused by the plastic faux bolt assembly and/or the pro-win combination.

I had the plastic assembly that came with the JG but it was shooting 350 FPS. I took it out and with everything exactly the same, I popped the stock hop-up and barrel all together into a metal CA one. Instantly, the gun was shooting 411 FPS. The metal one holds the hop-up unit MUCH further back and therefore when the mechbox nozzle hits it, it makes very tight contact and no air leaks out between the nozzle and hop-up. In fact, it was so far back, I had to sand a channel into the magwell feed lip to get BBs to feed a bit further back...And to test my theory, I swapped back in the old plastic assembly again and voila, back to 350 FPS. Metal one in and 411 FPS.

how did i miss that >.>

Oh well, thanks a lot SNK, and ill take a look at the hop-up tonight