Systema broke down on second mag!

Last week I purchased a Systema challege kit, I assembled it myself and everything seemed well. The kit itself is not complicated to assemble , the gearbox comes completly assembled. I finaly got to try it today as I had batterys... I put the battery in I nervously pulled the trigger , the gears wailed beutifully and placed themselfs where they should. PERFECT!


2 mags later the guns stops fireing completely!

I open the gun to see the gear that pulls the piston back was pointing upwards.. odd

I check the bolt stop switch, nope.

I checked the motor connections, all good.

I checked the fuse, Ahh burnt ! no problem, I change it,

Try it out the gears turn and reset to their normal position.

I put the cylinder in and shoot off a couple of rounds... stops fireing again...

Check the fuse, burnt, gear is also pointing upwards...

Put in new fuse, now it just burns the fuses right away and the gear stays stuck in the upper position.


What the hell? I hpe I did something wrong because I dont have a good impression on systemas right now.

[jameskersten]

I just finished my SCK the other week with a very similar issue. I replaced all the electronics to find out it was the motor. May not be the same issue with yours but check all the basic stuff first like no shorting wires, etc. I was lucky enough to have a teammate with a back up motor to try out and sure enough as soon as I changed the motor, it ran perfect since.

[jameskersten]

ps. I feel your pain all to well. Looking back I wished I had spent the extra $500 on someone at Systema assembling it. Hopefully yours is an easy fix.

holy shit, i hope its not the motor!god I tought these we supposed to be good!!!!

[jameskersten]

Have you tried posting this on the PTW users Group forum, they were honeslty a big help to me when I was out of ideas. Or if you bought it from A&A, try emailing Redwolf tech support and see if they have any ideas. When mine when bad, mark refered me to them.

[mcguyver]

What cylinder kit and battery are you using? If you used the M150 with anything but the 12 volt battery, you're asking for trouble. Also, make sure you have a charger capable of actually charging a 12 volt battery. Most R/C chargers are not capable of this.

Do you have the 490 motor or the 480?

Just so you are aware, many, many international retailers will not even sell the SCK without either assembling it themselves or not at all. And Systema does not warranty the kits at all. You guys want to save a couple of dollars to do assembly yourself on a gun that is 100% alien to all but a very few. There are at least 4 common problems that happen with self-assembly that can be the issue here.

1) Solder. If you have experience soldering, this is not an issue. And by experience, I don't mean you did it once in shop class. I mean you have done it hundreds or thousands of times. You can over-solder very easily, leading to heat damaged terminals, solder flux and solder in motor windings or on motor housing, leading to a potential short circuit.

2) Electronics failure. This can result from problem #1, and can also happen due to mechanical damage to the boards during assembly or during the soldering to do the burst mod. Have you done this?

3) Battery/cylinder incompatibilty. If you try running the M150 on anything less than a properly charged Systema 12v battery, you run the risk of damage. They sell the proper batteries. Use them. They also sell the proper charger, but you have to shop for an aftermarket one to charge 10+ cells, as well as do proper discharge. The MRC Superbrain 989 is a very good one for the PTW batteries. I've seen guys try to run the M150 with the 7.2v Systema battery and get blown fuses. 9.6v will also do that. M90, M110 and M130 need 9.6v PTW batteries, don't cheap out and get them built by anyone. M150 requires 12v.

4) Wiring damage. To be blowing the main fuse, this would mean damage to the EL-003 (switch board) to motor wiring. This could happen if you don't take proper care when routing the wiring through the receiver holes.

You may also have a motor failure, as James has described. You will need to provide a hell of alot more info if you want help on this gun.

[Regan.S]

If it's the motor isn't it only another 100? So your still saving 400 dollars so whats the big deal? Oh James don't you save 1000.00 dollars doing it yourself? 1599.99 for a PTW Challenge kit and 2499.99 for the PTW already assembled or is that wrong? Last I checked AA had it priced at 2500.00

[mcguyver]

Originally Posted by Regan.S

If it's the motor isn't it only another 100? So your still saving 400 dollars so whats the big deal? Oh James don't you save 1000.00 dollars doing it yourself? 1599.99 for a PTW Challenge kit and 2499.99 for the PTW already assembled or is that wrong? Last I checked AA had it priced at 2500.00

No. You're looking at the Gen 3 kit, not the MAX kit. Max kits in Canada are $2000, give or take a small amount. And a replacement 480 will cost you about $175 landed vs. the 490 at $300 landed. And when it's all said and done, you save maybe $100, have to build it yourself vs. having one QC'd and tested at the factory.

Would you trust having to build your own Ferrrari and expect it to perform the same as one built, tested and tuned in Italy? Common sense here, folks!!

[jameskersten]

I paid $2000 for mine from A&A, and I now agree 100% with mcguyver, SCK is not the way to go if your not 100% fluent in these guns. The money I spent on replacing the electronics when I thougth I fried them (adding burst mod), and the fact I may need to buy another motor has equaled if not more then the cost of just buying the gun assembled by someone who can do it in their sleep. Really the only way to get good quality control from these guns which we have come to expect is to buy it assembled.
And mine came with a 490 motor so if I don't get any warranty on this motor I will be out another $300 cause I would want to get another 490. I am using a 480 right now just cause thats what my teammate had as a spare but really you can hear/see the difference in rate of fire.

[mcguyver]

Here's alink from the PTW-users forum. It explains 1 of the problems from poor assembly practices:

http://www.systema-europe.com/Forum/...p?TID=1065&KW=

I'm not saying that anyone who assembles these guns is an idiot or anything, or that if there is a problem you were a twit for doing something wrong, but small procedural errors can lead to expensive problems. These are not a normal AEG here. They have extensive electronics for control and operation.

The factory builds them and tests them. Why mess with that?

And sometimes, parts will just break.

[jameskersten]

Off topic but does anyone have any ideas where to send a motor for repair (if possible) or would it be cheaper generally to just buy another ?

[mcguyver]

Originally Posted by jameskersten

Off topic but does anyone have any ideas where to send a motor for repair (if possible) or would it be cheaper generally to just buy another ?

Have you put a meter on this motor yet? There may be a short ciruit in the windings that is really not repairable. The problem may be from the excess glue you witnessed, putting the commutator off-balance, causing some rubbing between the commutator and stator.

I wouldn't think it would be worthwhile to repair it, as buying a new one would suffice. Perhaps they've had a bad run of 490 motors? They are brand new in design and construction.

[MadMax]

Originally Posted by mcguyver

3) Battery/cylinder incompatibilty. If you try running the M150 on anything less than a properly charged Systema 12v battery, you run the risk of damage. They sell the proper batteries.

I read about that. It messes me up.

From what I've been led to understand, DC motors display linear torque vs. current behavior. That is: for a given current a motor will output a given torque no matter what the voltage (steady state operation, not accelerating). Higher input voltage at equal current flow will mean that the motor will output the same torque as a lower voltage (same current), but the rotation rate would be higher.

Do not try to imagine this applying under a no load condition. Imagining a motor continuously rotating a winch, at constant velocity, lifting a weight on a rope is a good approximation. Continuous consistent torque, unconstrained rotation rate.

Therefore a lower voltage battery should be able to crank the same spring that a 12v battery would, but at a lower motor RPM.

If that is the case, then the torque required to crank a M150 spring, and subsequent current, is high enough to exceed the 30A rating of the fuse with ANY battery. Therefore, the only way a 12v battery would work but a 9.6v wouldn't would be because the 12v would have to motor turning faster and taking less time to power through the spring cycle exceeding 30A. Lower voltage packs would have the motor dwell at 30A+ load for a long enough period of time to pop the fuse.

This would be consistent with a 12v pack also popping fuses when they're at low charge state as their supply voltage would decrease.

If this is correct, I'd have to admit that the PTW design is pushed to the limit with the M150 spring set and is therefore not a really good design decision to include as the stock cylinder set.

I see a few possibilities for the cause of your problems Pawscal:

1. overcurrent condition persisting for sufficiently long with lower voltage batteries as described above

2. damaged motor windings: short between motor coils due to damage to the wire insulation ~ look for blackened charred spots in the coils

3. defective MOSFET in EL-003 assembly: One FET in the braking pair may be damaged causing a current sink (resistive short) that the forward power FETs are fighting

4. mechanical fault in cylinder set: a damaged piston tooth or some crud in the cylinder may be preventing the piston from pulling back freely. This will result in high current draw ~ inspect cylinder set, look for damaged piston teeth

I don't really see many other fault possibilities with the symptoms described. A solder blob in the motor comm would result in immediate failure of the fuse instead of partial cycle operation.

Damaged wiring insulation also tends to be pretty binary in it's failure mode. Shorts of such nature tend to weld together with an exciting pop and become pretty low resistance which would prevent partial cycles from occuring.

One other thing occurs to me: Did you tighten the grip screw? The current PTW builds require NO motor grip screw adjustment. The set screw is merely a plug for the bottom grip plate. If it's backed into the motor shaft it may be axially loading the shaft and increasing the motor load. If the motor rotates clockwise, it would have the tendancy to tighten the grip screw and increase the axial load to the bearings and screw.

[KEVORKIAN]

I chose to pick up my PTW Max CQB from MadMax & I have yet to have any problems...The money I saved by having it QC'd & built by him is well worth the added cost! I even got the 6-pack of mags in the deal !!! Quit wasting your money TRYING to save money...

Let this be a lesson to all who are looking into purchasing a Max SCK...

[mcguyver]

Max, the PTW is not of a constant-torque type. Generally, we don't see those very often. Because this is a DC motor that does internal pole reversal to generate rotation, you will see impedance, even though it's a DC circuit. The impedance of the motor is determined by by the DCR of the motor windings combined with the reactive load of the motor (connected spring load) to determine current draw.

The formula is:

Impedance (z) squared = DCR (R) squared + Reactive load (Q) squared

The resistive load will not change (unless you change the spring), and the reactive component of the windings is fixed, regardless of voltage. Increasing load will increase current consumption.

Now, considering that the connected load stays constant and the DCR stays constant (in a DC system), Power (P) = Voltage (V) x Current (I). If you drop voltage, the motor load stays the same and the DCR is constant, Z is constant and current rises. Rising current in a high-performance system with little room for deviation means blown fuse.

At least, this is how I see it.