Frakengun TM Mech Box Issue (Poof!)

[Savage Haggis]

"The only way you'll ever know how something works will be if you break it & have to fix it yourself..."

Truer words have never been spoken.

I have a Frankengun C7A2: CA Metal Body with TM Mech Box.

(Stop cringing, I haven't told you what the problem is yet...)

The initial issue was this: After a mech box rebuild the gun worked flawlessly for a couple of game days, then developed an interesting problem. When the trigger was squeezed the motor made a stressed whirring noise & the motor would bind (or sound like it was binding) & not fire. However... when laid on it's right side, the gun fired semi & full auto as normal. When held upright it made the same whirring noise & sounded as though it was binding up.

SO... decided to remove the mech box from the gun to have a look. However, before taking it apart I decided to try it one more time, making notes as to what it was doing & not doing. Laying on it's right side I squeezed the trigger in semi, pop pop pop, as normal. Switched to full auto & it rattled away as normal - then made a sudden SNAP, followed by a puff of blue smoke from the lower end of the mech box & stopped firing all together. I also observed that the spring is locked back in the compressed position. With power to the gun, it nows appears to be lifeless.

The gun & mech box extracted from the metal lower receiver relatively painlessly.

So, here's a couple of questions to a first time self imposed gun doctor:

1.) Is there a means to manually uncompress the spring BEFORE I take down the mech box?

2.) Thinking out loud, I believe I may have blown the switch out of it as well, but I'm turning to you, the pros who may have seen or heard of these symptoms before for possible ideas or repair opinions.

Thanks in advance, folks, this gun means a lot to me & I'd love to have it back up & running ASAP.

[Ibby]

To manually uncompress the spring before opening the mechbox you can rotate the bevel gear by hand using an appropriately sized flat head screwdriver. So long as your anti reverse latch isn't broken it should only turn in one direction.
I don't know what would cause the blue smoke, never seen that happen before. I'd guess the motor or the switch caused it. There's not much else in there that could. As for the gun only firing on it's side, it sounds like there's something loose inside the mechbox causing that problem. It shouldn't be hard to figure out, mechboxes are easier to work on than most people think. Good luck with it!

[Savage Haggis]

The bevel gear only moves one way, so the anti-reverse appears to be working.
However the bevel gear only moves so far, then snaps back.
I can't seem to move it far enough forward for the spring to release.

Any thoughts?

EDIT: Okay, it finally released! Whew! Just had to work at it a little further than I first thought.

[Ibby]

Originally Posted by Savage Haggis

[SIZE="1"]Okay, it finally released! Whew! Just had to work at it a little further than I first thought.

Yeah, it gets harder to turn the more the spring compresses. This is one reason why I like the 4 anti reverse position bevel gear over the 2 position. Having the 2 position bevel gear back up on you can make you think something else is wrong in the mechbox.

[roughshadow]

Blue smoke or seaming blue could be gray?

If the smoke was possibly gray the motor burnt out.
If the smoke was indefinitely blue you blew a switch and burnt it out.

These are comparable to electronics in general not specific to aeg kinda answers.

When you blow a "switch", witch is really really really hard, they literately blow. Inside there's a semicunducter dust when "burnt" gives a blue smoke. My moneys on the motor as it would have blown first. Also give the 2 parts a sniff ones going to smell crispy.

These answers are based on electronics experience.

[MadMax]

Too late, as you've already got your spring decompressed, but you can use this trick next time:

I like to take a long 3-4mm screwdriver and push the piston back thru the nozzle. Seat the driver carefully as you don't want to skid across the piston face and scratch the cylinder. You also don't want to bend the nozzle. Do not do this with silent piston heads as you may end up cutting the rubber face on them.

Fastest way to decock stuck mechbox.

It sounds like you've got an intermittent electrical short which occurs when you tilt the gun a certain way. Look for blast marks on the spade terminals and connectors. I'm wondering if you've got a short across the motor plate.

*on second reading* It sounds like the motor is toast. I'm guessing that you may have gotten something inside the motor can. Maybe a shim or fastener which was causing a grinding noise in some orientations. Eventually it may have shaken loose and damaged the coils or commutator causing a severe short and total motor failure.