Stug III gun constantly firing

[Tiger6136]

first post!

Have a few 1/16 tanks from Tamiya and an old Heng Long Tiger 1, also a 1/8 Panther and half way through a 1/6 Tiger build.

I received a Stug as a present but the main gun is constantly firing. As soon as it is powered on it starts. The multi function is working fine, I swapped it with another a friend had. Removing the cable to CN9 connector allows the tank to run so the problem must be somewhere else further up the system.

Anyone got any ideas?

Many thanks

Graham

[MichaelC]

Is this an IR tank ? Sometimes the trigger micro switch gets stuck on the recoil unit. You might want to check that. It could also be the recoil is jammed against the micro switch as well.

[Dietrich]

Hi,
The same issue can arise with the BB gun firing...a stuck switch towards the rear of the main gun..
Alb.

[Tiger6136]

Thanks for the suggestions. Will check it out, hopefully thats it.

Graham

[Tiger6136]

No success!

Have taken recoil unit out and apart and assembled again, still constantly firing.

This is the ir version - leaves me wondering if it could be the transmitter and that one of the trims is wrong?

Thanks for the advice - still looking for soltion

[MichaelC]

Well, it could be the trim. Is the left stick trim pushed all the way up ? Also, when you say it won't stop firing, is it just the sound, or is it the whole reocil/firing flash and sound ? I do have this happen to me once in while where it won't stop firing (sound only) but it goes away if I turn it on and off. I just figure it is a ghost in the machine thing. Obviously you have turn it on and off multiple times.

CN9 has turret rotation motor, machine gun+headlight and then the the gun motor control so it can only be that. You should have a 2 pin connecter splitting out the 8 pin right ? If you unplug the 2 pin connector you should get everything else (i.e. turret rotation/MG/Light etc) and there shouldn't be any firing at all. This would isolate the problem more specifically.

Pics might help too........

[Tiger6136]

Have attempted to get a couple of pics to help.

Its not the rx - the left trims are disabled.

The connections do not appear to match the wiring diagrams posted on the two 8 pins units.
As soon as it has gone through start up the recoil motor runs at full. i may be missing something obvious

speed

Thanks for the help

[MichaelC]

Hmmm......What happens if you leave CN-9 plug in, but unplug the 2 pin connector that is connected to PIN 4/5 on CN3 ? Does the tank still fire ?

The wiring looks okay from here and you haven't mod anything, right ? The other problem could be that it was wired wrong to begin with which means that you might have to retrace everything.

[Tiger6136]

Unplugged the 2 pin on 4/5. Recoil motor still running flat out. Track recoil and sound work.

For some reason it is getting full power as soon as I power up.

My gut feeling is that it may well be wired wrong, some of the soldering is very poor. i think that will have to be my next job

[MichaelC]

If unplugging 2 pin plug on 4/5 and you are still getting everything firing then it must be a neg/pos got mixed up and you are getting full power to everything all the time. Just do a visual trace and it might very well be a simple neg/pos mixed up at the two 8 pin connector board. The RX-18 should be good (since you swap it with another good one and it is doing the same thing). Just following the RX-18 diagram (I am sure you have it but just in case).

You are right though, the soldering on the two 8 pin connector boards looks less than impressive and not even up to the usual HL job.......