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Simon Rees

Electrical problem in a CA M15A4 RIS Sportline

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OK, so yesterday I finally got round to fitting my madbull 3 in 1 hop and Black Python Ver 2 TBB in my 10 month old Classic Army M15A4 Carbine RIS Sportline.

 

Split the gun, removed the old barrel and hop, put in the new one. Easier than I thought and no drama.

 

Put the gun back together in the normal way and put the pins back in.

 

All going swimmingly so far.

 

Gun was firing fine before the split (Last used on Saturday afternoon), but upon putting a battery in and trying to fire to check the new set up, no joy, Nothing, Zip, nada.

 

Checked battery, fine. Used alternative battery, still nothing. Charged first battery for a bit and retried, just in case. Still nothing.

 

Checked motor connections and seem OK.

 

Am I missing something obvious or is there some trick I need to know?

 

Thoughts and potential solutions most welcome.

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Hmm

 

Have you checked the actual battery and gun connectors? It might be that they're not meeting properly for some reason or other. Or the fuse might've blown, if there is one. Unlikely but you never know until you check.

 

Other than that I can't think of anything else.

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Thanks, Ed

 

Connector is OK I think. There's a small extender that goes through to the stock (rear wired) and when you disassemble the stock assembly and tube you can dis-connect that and then connect the battery direct to the gearbox/motor and still no joy.

 

No fuse visible on my cursory strip down (not taken the GB or motor out yet), and none visible on the exploded diagram:

 

http://chairsoft-press.com/wp-content/uploads/2009/03/205_c7_m15a4-cqb-manual-exploded-diagram-p7.jpg

 

I'll strip and re-assemble from the ground up later. :-\

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Seeing as the lower part of the receiver would not have needed to be touched to change the barrel and hop unit, it is difficult to see where anything could have gone wrong sufficient to stop it working. Just out of interest, have you tried splitting the receivers again and just testing it in the lower? If so, does it still not work? If it doesn't then the likelihood is either a broken connection between the battery and the motor, or just possibly a broken brush contact spring on the motor itself. I've had that happen to a couple of cheaper motors. The spring has bent sufficiently to come away from the copper tails on the brushes, disconnecting the motor from the power. Worth dropping the motor plate to check, as it might be nothing at all to do with changing the barrel & hop. It might have happened anyway.

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Thanks RR01. I agree - I think the barrel change is co-incidental to the problem. Other than physical proximity to onw another, there is nothing linking the receivers.

 

Split it again last night, took the motor out, tightened up the contacts and checked what I could see without further stripping. All appeared to be in order. Re-installed the motor, still nothing. Took it out and pushed the contact springs firmly on and made sure there was contact with the copper tails etc.

 

Still nothing.

 

Wondered if the trigger/safety had an issue (the safety is physical and electronic), so played around with these for a while and then it seemed to heal itself. First one random shot (scared the life out of the wife, the dog and me!). Bit more fiddling, re-assemble and it fired a further 5 or 6 shots in quick succession. It was late so I didn't want to keep testing with the associated noise, so will go back to it tonight.

 

Not sure what went wrong or what happened to fix it, which is a pain as i can't then replicate the fix if the error re-occurs, but I'll settle for a firing gun that I can now test the barrel and hop set up in!

 

Thanks for the replies.

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One other thing to check, although it will take a gearbox strip to be sure. I have had a problem where the moving trigger contact has only partially retracted on Semi, enough so that it wasn't making contact, but not enough that the back edge dropped down so that it would reconnect with the top of the trigger itself again. This can be caused by wear in the return spring, a loose fixing screw, a tiny restriction in the movement of the sliding trigger contact, or even a bit of burning on the thin trigger contacts themselves. If it happens again then a strip down and detailed examination may be the only option, as well as checking the circuit wires for continuity with a multimeter.

 

One trick if you find the moving trigger switch doesn't slide smoothly; rub the sides and bottom with a pencil lead, as that adds graphite to the plastic, the slipperiest substance known to science. It will cost you nothing and being electrically conductive, if it got on the contacts (very unlikely) it would not hinder conductivity.

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Thanks. Might give that a whirl. Got a few weeks before my next skirmish so time to tinker.

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