ics m16 a3 electrical gremlin

[six4]

at the last burma game my rifle was giving me the symptoms of a weak battery. it would fire through a 100rd mag then give out,,,after a few seconds something like 30 or so it would fire through another mag then give out again. took it home and after stripping it down i found the red fuse lead to be hanging by only a few strands. so i replaced the entire assembly and used solder and shrink wrap for a solid,clean connection.




at weds, evening game it did the same thing,but not until about 600rds this time. i took it apart again to find all the wiring intact.

cant be the battery because i have the same symptoms with 2 other ni/cads. i took the motor to warcraftgames for matt to inspect and its been cleared as a suspect. im really stumped on what to do next,,,,,,

[ILLusion]

Maybe it's your charger? Or your charging process that's not fully charging the batteries?

[six4]

Originally Posted by ILLusion

Maybe it's your charger? Or your charging process that's not fully charging the batteries?

was thinking that myself,but the other two batteries that gave the same symptoms were from a friend and not used on my charger. however,,,previous charger was only meant for 7 cell ni/cad my 9.6 2400 is an 8 cell and i used the 7 cell charger twice on the 9.6. i have a proper charger now.

and im currently doing a second reconditioning as we speak. since your a gun tech does this theory make any sense?,,im still suspecting the motor,,could it be fine when in a cold state but once under load could it be causing some drag? the rifle is a year and a couple months old now.

[walks]

try to get a look at the contact points in the trigger switch in the mechbox (cant think of the name right now) ICS M4/M16 are known for the contact points burning out, mine was so bad that it started to melt the plastic that held it in

[Renegade)]

Seconded as a possible, mine went big time as well, had to get a whole new assembly. Not a single problem since.

[ILLusion]

I third that suggestion. A physical thinning of the circuit will draw more and more current in order to push through the bottleneck. It also presents a safety hazard.

[Kos-Mos]

I think it can be the trigger too.. (Not officially a gun tech.. but still...)

Try using somebody else's trigger or just change it. If your problem is gone, then buy a MOSFET and you won't hear from it again.

[six4]

Originally Posted by ILLusion

I third that suggestion. A physical thinning of the circuit will draw more and more current in order to push through the bottleneck. It also presents a safety hazard.

i had that problem about 2 months ago i had to change the wiring harness. the contacts were worn pretty good to the point that they were arcing. i will take my rifle to the field to try it out after re-conditioning the battery to see if its solved.

[ILLusion]

Originally Posted by six4

i had that problem about 2 months ago i had to change the wiring harness. the contacts were worn pretty good to the point that they were arcing. i will take my rifle to the field to try it out after re-conditioning the battery to see if its solved.

Did you check the copper contacts at the trigger? Sometimes, if the gearbox isn't shimmed right or if the spring is too heavy, it can cause severe arcing across the contacts, which can ultimately burn holes through them. This again, will result in a bottleneck in the circuit.

[Dark-Angel]

shouldnt we install a diod to solve this problem? arcing can be pretty bad if you go sensitive electronics or other stuff tuching the metal where its arcing.

[mcguyver]

When a motor in a DC circuit is under load, all mechanical switches will present an arc. In AC circuits, the current oscillates in both directions 60 times per second (in North America), so arcing isn't as pronounced, but still there. In DC circuits, the current only flows one direction, so arcing is very damaging. That's why electrical equipment rated for 250V AC is very often limited to a max of 48V DC with switch contacts.

Depending on the type of material used, arcs can either be destructive quickly or barely noticed. Softer metals like copper are very poor contacts, as they get pitted and oxidized very quickly. Harder metals like tungsten and many nickel alloys make good contacts as they can resist pitting for a long time (decades in many cases), like the switches in your house for lighting.

ICS uses copper switch contacts plated with a mystery metal, presumably to counteract pitting. Unfortunately, simple plating is not going to last.

[ILLusion]

Originally Posted by Dark-Angel

shouldnt we install a diod to solve this problem? arcing can be pretty bad if you go sensitive electronics or other stuff tuching the metal where its arcing.

Yup, that's what MOSFETS are for...

Or, you could look for the actual SOURCE of the problem, rather than just fixing the symptoms. lol. If something actually is creating enough resistance to cause burnouts of components, you need to find out what it is, understand why, and fix it.

[Dark-Angel]

mosfets are just a form of power switch, in my electronics courses when using transistors ,wich are very similare to mosfets but the way they work is diffrent, we had to use protection by using a diod in inverse mode, so that the curant wouldnt creat a short but would protect from arcing because of the 700ish volts needed to go throw it in inverse. Because when turning on or off a transistor ,and im pretty sure a mosfet to, with high curants there is a chance of arcing and thats why we use a diod.

[Ibby]

Arcing within a transistor or mosfet should be less than negligible. In a mechanical switch in a DC circuit, yes it'll be terrible. One way to reduce it is to put capacitors on whatever is causing the draw, in this case the motor. I had the dreaded ICS trigger arc on both my M4's. My main one was so bad it melted like someone already mentioned. I had a new one handy and installed it. It's beginning to wear out now, but the process has taken much longer than normal since the capacitors went in. A small one on each motor terminal will do the trick. Take a look at how RC cars are set up and you'll see what I mean. You likely won't fit them in the handle, but as long as they're between the switch and the motor they seem to work fine.

[six4]

Originally Posted by ILLusion

Did you check the copper contacts at the trigger? Sometimes, if the gearbox isn't shimmed right or if the spring is too heavy, it can cause severe arcing across the contacts, which can ultimately burn holes through them. This again, will result in a bottleneck in the circuit.

i went to an op-for game to switch out a loaner motor,,,and then it started popping fuses. at that point i realized that it was beyond my capabilities to repair and i left it in the hands of a gun tech. apparently "jasper" from op-for says it was my selector plate not dropping into the right place because of worn shims that was causing the draw. the shims werent to bad,,but enough to cause the "bottleneck". i will be testing/picking up the rifle on saturday the 14th. if all is well i will get a better description on what "jasper" did to fix my rifle and post that up in the aeg solutions section for anyone else who may have this problem along the way. for now im calling this problem solved and would like to thank everyone for the time and ideas.