Troubleshooting AEGs....General Process, Tips & Tricks and "How to stay sane"

[m102404]

First...I am by no means the be all and end all guru of AEGs. There are FAR, FAR more competent gun docs than myself. That said, I've fiddled with more than a few over the years and think that I have a decent working knowledge of what it takes to make them tick.

Secondly...there are ALWAYS more than one way to skin a cat, so any specifics written by me should be taken with a grain of salt, and all other opinions/techniques/etc should be considered as well.

PURPOSE:
The purpose of this post/thread is to provide concise, well written, proven processes and procedures to consider when troubleshooting AEGs. The same questions (from an experience point of view) get posted over, and over and over. Fair enough when taken from the newbie perspective...but painfull to reitterate an answer every time.

AUDIENCE:
This post/thread is aimed at the persons who are a newbie/neophyte at troubleshooting their AEGs. This does not solely mean the "just started haven't played a game, bought the first thing I could find and it doesn't work" persons.....this may be helpful to those vertran shooters who haven't a clue aside from inserting a battery, adding BBs and slaying bodies (we all know at least someone like that....I for some reason know several ).

CONTENT:
I will endevour to keep the content relevant. Things change over time, but the fundamentals don't. This post/thread will NOT detail how to shim...it will NOT detail how to set your AOE...it will NOT detail which gear ratio workes best with what spring to match which motor to result in what FPS and ROF.

This thread WILL refer to such things though...and the search function is just a click away.

I will try to keep linking in other concise threads that are helpful to those specifics (and there are some very nice ones buried somewhere on this forum). An I will, of course, be more than open to including any info from others that have something concise, accurate and well written to add.

[m102404]

* SAFETY NOTE *
1. Assume every gun is loaded
2. ALWAYS point the muzzle in a safe direction
3. ALWAYS keep the trigger clear until you're ready to shoot (primarily your finger...but tools/clothing/rags/slings/etc...too)
4. See that the gun is safe...or confirm that it is in the condition that you want it to be in (this may mean clearing the gun, disconnecting batteries, removing magazines/boxmags/gas/etc...)
5. ALWAYS wear protective gear (i.e. ballistic glasses, etc...)


"I pulled the trigger and nothing happened"
1. Be more specific about "nothing"
- did the motor try to turn (may make a thunk sound or you may feel it in the grip try to start)
- did the gun cycle, but no BBs came out
- did the mechbox partially cycle...but didn't complete it's firing cycle

2. Depending on the above...the root issue may be a number of things
- your battery may not have a sufficient charge to cycle the mechbox
-- your battery may not be "good" any more...and even if it appears to hold a charge, it may not be good enough really
* You do not need BBs or a magazine to test this...see SAFETY NOTE...use a "known good" battery that is fully charged...put the AEG in full auto...pull the trigger fully to the rear for a second.

- your fuse may be blown
* check your fuse holder and inspect the fuse. Most blown fuse will have some visual indicator that it's busted (and if you're looking at a burned/broken fuse and still can't tell if it's any good...you shouldn't be using air). Thermal fuses (resetting or not) may not have visible signs that it's tripped....but they'll be really, really freaking hot right after they've tripped and need to be cool to the touch before you're good to try again.

- your motor might be mis-adjusted or worn out enough it cannot cycle the mechbox anymore
-- Motor too high
* Motors will tend to jam if they're screwed in too far up into the mechbox...back the motor adjustment screw off a half turn at a time. NOTE. If it was working yesterday....and not working now...the motor probably hasn't screwed itself in spontaneously (they tend to unscrew though sometimes with use). But if you just rebuilt your gun and changed gear sets, motors, grips, etc....you may need to set your motor height
-- Weak motor
* If you take the motor out of the grip and hook it back up to the wires, pull the trigger and motor spins....it does NOT necessarily mean that the motor is good. I DOES mean that the motor is receiving electricity when the trigger completes the circuit.
* The simplest thing is to try a Known Good motor...either a new one...or one that's working just fine in another AEG.

- there's a problem in your wiring
-- electrical connectors can become worn/loose...they may work, then not work as they heat up/vibrate/get shaken around.
-- ALL the wires in your mechbox should be continuous, shielded and not pinched. Nicked, cut, pinched wiring has to go.
-- Connections have to be either made with a good, solid connector (DEANs...or at a minimum a tight fitting Tamiya)...and all connections to wire must be soldered (i.e. wire to switch...wire to motor connector...wire to battery connector...wire to fuse holder...etc).
-- The number of connections should be minimized.
-- Any spade connections (i.e. a motor terminal connection) must be tight and have as much contact area as possible
-- all connections must be insulated (i.e. shrink wrap)
-- the wires you use should be of sufficient quality such that they do not add substantial resistance to the electrical circuit (ok...dumb it down for Joe-average....if in doubt use good quality 16-18AEG copper solid strand wire)

[m102404]

* SAFETY NOTE *
1. Assume every gun is loaded
2. ALWAYS point the muzzle in a safe direction
3. ALWAYS keep the trigger clear until you're ready to shoot (primarily your finger...but tools/clothing/rags/slings/etc...too)
4. See that the gun is safe...or confirm that it is in the condition that you want it to be in (this may mean clearing the gun, disconnecting batteries, removing magazines/boxmags/gas/etc...)
5. ALWAYS wear protective gear (i.e. ballistic glasses, etc...)

"My gun is shooting...but nothing's coming out" (really...your gun is cycling...but BB's aren't feeding properly)
- Hicap mags (even though they're ghey)
* ensure that you have sufficiently filled the mag...doesn't have be jammed full, that may actually jam the BBs in the feeding mech.
* Insert the mag into the gun first...then wind the mag until it either skips/ratches/doesn't turn any more...you should be able to feel that there's good spring tension there

- Your mags aren't feeding BBs up hard/fast enough
* fill your mag will BBs...don't try to jam the last few in as hard as you can, you'll squish the springs in the mags...stop when you're feeling resistance, or better yet know how many BB's come out with each plunge of your loader and count how many are going in. Pull the BB retaining latch back and the BB's should SPRAY out of the mag. If they dribble out like the beer did from Minnie Driver's mouth when she told her joke in Good Will Hunting...then like Minni Driver, it's just no good. Stretch the mag spring...or toss the mag and move on with life.

- Your mags aren't sitting high enough to release BBs into the hopup chamber
* The feeding tube that leads to the hopup chamber needs to fit into the hole of the mag that's holding the BBs. It has to physically fit...so if the tube or the mag is mangled, over sized, etc...it won't feed properly. With some hopups you can take the hopup out and press it ontop of the mag and BBs should spring out and into the hopup.
* when the mag is seated into the gun and the feed tube is positioned into the mag....the rim of the feed tube will push back against the BB retaining catch and cause the BBs to release (like the spray your BBs out of your mag test above). King Arms mags used to be (and may still be) problematic like this...when inserted they'd shot one shot and then not feed. If you trim back the catch a bit, they'd work fine. Search for King Arms Mags Not Feeding and Trim BB Retaining Catch

- BBs aren't getting past your houp rubber
* a JAM will produce a much different sound vs. a blank shot. The mechbox will sound muffled and plugged up (because it is). ANYTIME you get a jam, you should stop...clear your gun...make it SAFE and clear your hopup/barrel (usually with a cleaning/unjamming rod....not a thin twigg unless you're really hard up in a big game). It could have been grit/dirt/misshappen BB/etc... Try again.
* your hopup rubber may be torn/dried out/buckled/etc....such that it is holding BB's too hard. On a gas gun, blow a mag of oily gas through the gun, let it sit for a bit and try again. Usually you're faced with taking the hopup/rubber/inner barrel out of the gun...inspecting the parts and reassembling
* your hopup may be set ON way too much...search Setting Your Hopup. If you find that you need to set your hopup on so much to get decent hopup effect/backspin that it's jamming up your gun....then it's time to change out to a different hopup rubber/nub.

- BB's may be clogging up in your barrel
* Use only good quality BBs...BBBastard is a quality Canadian brand that is widely trusted and used by many.
* See Safey Note...clear your barrel...clean your barrel...search Cleaning Your Barrel

- Your nozzle/tappet may be broken
* you're going to have to take your mechbox out, inspect the parts and reassemble. Search Mechbox.com for disassembly and mechbox tutorials

[m102404]

* SAFETY NOTE *
1. Assume every gun is loaded
2. ALWAYS point the muzzle in a safe direction
3. ALWAYS keep the trigger clear until you're ready to shoot (primarily your finger...but tools/clothing/rags/slings/etc...too)
4. See that the gun is safe...or confirm that it is in the condition that you want it to be in (this may mean clearing the gun, disconnecting batteries, removing magazines/boxmags/gas/etc...)
5. ALWAYS wear protective gear (i.e. ballistic glasses, etc...)

"My gun shoots BBs...but seems to be ok at first but then slows down"

- motor might be failing
* could be the motor brushes loosing consistent contact with the comm
* could be the magnets have lost strength...as it heats up with use it actually becomes weaker

- circuit/wiring may be compromised
* see wiring notes in previous post

- battery may be underspec'd for your setup...or be wearing out...or need charging
* use a known good battery...use a large battery. Mini batteries tend to be fine for a while and then quickly loose their effectiveness. When batteries rest for a bit they may appear to provide sufficient power...but if they're low or dying they'll quickly tail off after another bit of use.
* using an underspec'd battery for a setup might seem ok for a bit...but then lead to inconsistent performance. Basically a battery will be able to provide a "peak" amount of power very briefly...then settle into providing a lower "continuous" amount of power.

[Azathoth]

This should be sticked and kept clean of any post that isnt related to easy trouble shooting.

I want to add

"My gun is shooting...but nothing's coming out"
- BBs aren't getting past your houp rubber

Have you done any modifications to your hopup unit? Adding teflon tape or other buffering materials to create a 'better airseal' in many cases may tighten the rubber and bucking to the point that you cannot get a BB past. You may also be using an inappropriate rubber for the hopup unit that you are using such as a hard Rubber for low FPS application (<400-450) when you should be using a softer and supple rubber.

MY FPS DROPPED LOTS AFTER I DID "X"
Undo what you did and see if that corrects the situation. If you are messing around with your hopup unit with teflon tape etc. You want to ensure that the hopup unit sits as tight as possible against your gearbox and air nozzle. Most of the FPS losses occur when users are trying to squeeze more power from their guns by adding tape, gasket sealer where it has no place to be, or using too much of it.

"I pulled the trigger and nothing happened"
You may have over shimmed your gearbox or it is overshimmed, or the AR latch is jammed or misaligned. You will need to take the gearbox out and inspect the internals. When the gearbox is screwed down without the compression system the gears should spin freely when manipulated with your fingers.

The most common culprits are listed in TYS post in the order listed. In addition to your battery perhaps being insufficient. Your CHARGER maybe the reason why your 'quality' battery is not pulling it's weight. DO NOT BUY OR USE WALL CHARGERS THAT COME WITH GUNS. Go to a RC shop and buy a quality charger, you will get far more out of your money at a RC shop in terms of quality and features than from a airsoft dealer. A quality Charger will save you money on batteries.

[m102404]

* SAFETY NOTE *
1. Assume every gun is loaded
2. ALWAYS point the muzzle in a safe direction
3. ALWAYS keep the trigger clear until you're ready to shoot (primarily your finger...but tools/clothing/rags/slings/etc...too)
4. See that the gun is safe...or confirm that it is in the condition that you want it to be in (this may mean clearing the gun, disconnecting batteries, removing magazines/boxmags/gas/etc...)
5. ALWAYS wear protective gear (i.e. ballistic glasses, etc...)

"Why does my gun seem so slow?"
First...define "slow" a bit more.
- is the Rate Of Fire (ROF...how many shots complete per minute or per second) slow
- is the actual speed of the BB slow (measured in FPS...Feet Per Second)

Slow ROF
- a slow ROF will result from either one, or a combination of the following:
-- The battery is weak and/or underpowered for your motor/spring/gear ratio
* Change out to a fresh battery...and/or a battery with either larger cells (2/3A -> SubC)...and/or a battery with a higher Voltage (note: voltages higher than 8.4V will significantly accelerate the wear in the switch...search Burn Contacts or Burned Out Switch)

-- the motor is weak
* see other posts regarding weak/worn motors

-- the motor simply doesn't have the speed or torque necessary
* change motors...some motors are better at high revolutions vs. producing torque. High speed motors are meant to pull "weaker" springs...High torque motors will pull stiffer springs, but perhaps not with the same RPMs.

-- the spring is overly stiff for the combination of gear ratio, motor power and battery
* dropping the power level down to the next strength of spring will increase your ROF if all else stays the same

-- Inappropriate gear ratio
* standard ratio gears...are just that, they are the "original" gear ratio used. TM's stock gear ratio (built for 1J guns...approx 320fps w/ 0.20g BBs...m90/m100 springs). "High Torque" gears will have a larger gear ratio (i.e. ~22:1)..."High Speed" gears will have a lower gear ratio (i.e. ~15:1). If you're pulling a really stiff spring with a high speed gearset...you're making the motor work a lot harder, demanding more of the battery and in general overstressing the teeth of the gears.

-- your wiring is compromised
* see notes in other posts re. wiring

Your FPS is slow (or really low)
- Is it really? Or you just think it is?
*** all FPS references are assumed to be using 0.20g BBs...unless stated otherwise
* You need a good reliable chronograph to actually know...the chronograph needs good batteries in it. Even a good chronograph will have a 1-3 fps variation in it...so think in increments of 5-10fps, the extra couple of FPS isn't going to matter.
* Springs are rated in %...and M/S (meters per second). Search Spring Chart. % is in reference to the "standard" TM stock spring. It is ~300fps = 100%...150% = (300+150) = 450fps...110% = (300+30) =330fps...etc...
* Springs rated in M (or MS) are a straight meters/second (multiply by 3.3 to get FPS). So...100M/S = 330FPS...120M/S=396FPS...etc...
* various "upgrades" will affect FPS...tightbore barrels, bearing spring guides, bearing piston heads, etc... Search What to Upgrade, search Greylocks, search Skruface
**** you need to be able to measure your FPS and have an actual expectation of what it should be....before you can say that it's shooting slower than it should be.

- cyclinder might be mismatched for inner barrel
* full cylinders are meant for long inner barrels (i.e. AK/M16)...Type 1's are meant for 363mm barrels...etc...
* there are differen labeling systems in use...they mostly follow the same pattern. Google search AEG Cylinder Types...there's a nice little list out there
somewhere
* the purpose of the porting is to allow the piston to build up speed before it starts trapping air to push the BB down the barrel....an MP5K ported cylinder (the port is about in the middle) will not have sufficient volume to push a BB down a long M16 length barrel...it might come out, but not at the velocity it's supposed to. Even a full cylinder might not push enough volume of air to send a BB out a 590mm inner barrel at the speed that the "spring should be". Take a properly setup M4 carbine (3/4ported and 363mm inner), and blindly swap a 509mm inner barrel to be covered by a suppressor....and you may end up with a gun that shoots slower than when you started.

- air leak
* an air leak forms when any combination of the following air-seals are less than perfect...piston o-ring to cylinder...cylinder to cylinder head...cylinder head nozzle to nozzle...nozzle to hopup/hopup rubber....hopup rubber to inner barrel
* there are dozens of things that can go wrong here...and this is not the place to go into each of them...but here are some quick tests.
** when the mechbox is apart...put your finger over the cylinder head nozzle...push the piston into the cylinder quickly and it should stop nearly immediately.
** same as above...but put the nozzle on the cylinder head nozzle, keep it forward a bit to simulate it being pressed out into the hopup....the piston should stop nearly immediately and there should be no leaks
** With the tappet/nozzle as forward as possible with the mechbox done up...press the hopup onto the mechbox/nozzle...then blow into the muzzle of the inner barrel...there shouldn't be any leaks.
** With the rifle fully reassembled...see SAFETY NOTE...do the same blow in the muzzle test (be careful that you're actually blowing into the inner barrel...and not the outer barrel...on some setups you won't be able to do this test)


****NOTE****
If all the above sounds like greek to you....then either search/research the crap out of it all...or seek help from a gun doc.

But being able to better describe and pin down where the issue is ends up being really helpful.

[The Chad]

What about......


Identify the issue
Gather the facts
Consider the possibilities based on the facts
Develop an action plan
Implement the action plan
Observe the results
If resolved, discontinue process
If not resolved, start again at gather the facts.

Base troubleshooting model, you should never attempt to resolve an issue without it.

[Invasian]

Great post Tys!

This should be sticky'd

[Renegade)]

I was going to do a full write up on one of the most common AEG issues, trigger post break. I just fixed what feels like the 100th one.

Very common with reinforced mechboxes, I know right? They are significantly less thick than stock boxes.

How to fix it is easy:

Symptoms:
Your AEG suddenly stops firing and you have no power whatsoever.
Checked your battery, connections, motor wires, all good, no power.
The trigger moves back and forth, but feels weird, as if its not engaging anymore.

Cause: The little post that sits behind the trigger block broke and now the trigger block is behind the trigger so it no longer engages.

Fix: Disasemble your entire AEG, and your entire gearbox until you are working with just the shell.
-Locate the broken trigger post, you don't want this loose inside your mechbox.
-Get a small metal drillbit, drill a hole right through where the trigger post was.
-Find a small hex, fine threaded screw slightly bigger than your hole.
-Thread in the screw slowly, make sure it bites and is tight, and screw it in all the way through the mechbox shell.
-Remove the screw and use some superglue, put this on the threads, and screw it back in. Leave it to try for a few minutes.
-Cut the head off the screw, and sand/file the screw head and the side of the screw that the gears are, make sure they do not touch the sector gear.
-File/Sand the other side of the screw on the outside of the mechbox, cant have any protruding and touching the selector plate.
-Reassemble your gun, make sure to test the trigger block, make sure you left enough that it sits at least up into the center of the trigger block.

Your now good to go with a new trigger post that won't break. I do this to all new mechboxes in advance or any that I take apart and tech. Saves you doing it again later, because that post is going to break.

[Spawn28]

Great thread Agreed should be stickied