wiring meltdown

[fladeere]

my 4310 stopped suddenly...seemed like the fuel cut off. When I got into it...discovered that the fuel shutoff solenoid failed, and (since there is no fuse) the wires from that point nearly back to the dash completely melted. The ground was especially burned. Seems like a lousy, and potentially dangerous, setup given how the wires wind around in there. Wondering if anyone else has experienced a failure like this. When I called the dealer before I tore into it, they immediately suggested the solenoid, so I'm curious if the problem is widespread.

Thanks for any responses

 

[RRacing]

I had a simular problem with my JD 790. But I found I had a shorted battery And my solinoid was fine ( even though I had melted wires as well, and like yours I saw it more on the ground side) . Luckly the 790 has a 3 amp fuse that blew before any major damage. You might have a battery going bad as well. Being the current goes up as the voltage drops.

Jim

 

[TMcD_in_MI]

</font><font color="blue" class="small">( You might have a battery going bad as well. Being the current goes up as the voltage drops. )</font>

Jim,

I'm a little confused by this. (Normal for me) Don't you mean current goes down as voltage drops?

Tom

 

[RRacing]

Tom,
The current draw of the solinoid goes up as the voltage drops is what I was saying.not that of the battery. But what is using the current meaning the solinoid.Hope this clears it up some. /forums/images/graemlins/smile.gif
Jim

 

[TMcD_in_MI]

</font><font color="blue" class="small">( Tom,
The current draw of the solinoid goes up as the voltage drops is what I was saying.not that of the battery. But what is using the current meaning the solinoid.Hope this clears it up some. /forums/images/graemlins/smile.gif
Jim )</font>

Jim,

Thanks for trying to clear up my confusion. I don't mean to make a big deal out of this, and we can just drop it if you want, but I'm still confused. Ohm's Law says that when the voltage on a circuit drops, the current through that circuit drops proportionally. So when a battery starts going bad and its voltage drops, the current coming out of the battery and going through the solenoid must drop, right? Am I missing something?

Again, feel free to just drop this if you want.

Tom

 

[RRacing]

Yes Tom you are right about the battery current dropping with voltage. But the solinoid will draw more current as the voltage drops to keep it open. Once again I'm talking about the object using the current not the one feeding it. Just because the voltage and current are dropping at the battery doesn't have anything to do with the fact the the object useing the current acts differently not the same way . It actually increases current trying to stay open. If you have worked on any CNC equipment or even automobiles with DC systems You will have seen this type of problems were the power supply starts to go out and the other components will start to draw more current and fuses blow and wires will melt. I hope this helps.Kurchefs law( I know I butchered that up) /forums/images/graemlins/smile.gif

Thank you
Jim

 

[TMcD_in_MI]

</font><font color="blue" class="small">( Just because the voltage and current are dropping at the battery doesn't have anything to do with the fact the the object useing the current acts differently not the same way . It actually increases current trying to stay open. )</font>

Hey Jim, thanks a lot for answering. Just so I understand, are you saying that it's possible that the battery can be putting out, say, 300 amps, but the solenoid can have more than 300 amps passing through it? This sounds kind of impossible to me. Am I misunderstanding you?

Tom

 

[RRacing]

No Tom thats not what I'm saying. The solinoid is wired for 3 amps and would most likely only use 2. But if your battery shorts and voltage drops, a curcuit that is only designed for 3 amps is now drawing 6-8 amps.( Possible more) which would cause the wires to heat up and maybe melt.Also if the battery was shorted or plates buckled It would draw even more.I use to work at Beretta the gun company many moons ago and we would get brown outs ( not Black) were the lights would dim for up to a minute which was a drop in voltage and before anyone could hit the kill switches on the CNC machines the current used by the machines ( Motors , Encoders , Controls,Solinoids, ECT,ECT) would surpass the wiring and motor windings were designed for, and just burn many things up. We would spend days replacing, and repairing, and even rewiring machines /forums/images/graemlins/frown.gif
Does this help any?

Jim

 

[RRacing]

I guess in a nut shell what I'm tring to say is the wiring that is only designed to handle X# of amps becomes your fuse link and it heats up just like a fuse because your object( the solinoid ) is drawing more current than it was designed for. /forums/images/graemlins/smile.gif
By the way did you get your tractor fixed?

Jim

 

[TMcD_in_MI]

</font><font color="blue" class="small">( ... we would get brown outs ( not Black) were the lights would dim for up to a minute which was a drop in voltage and before anyone could hit the kill switches on the CNC machines the current used by the machines ( Motors , Encoders , Controls,Solinoids, ECT,ECT) would surpass the wiring and motor windings were designed for, and just burn many things up.)</font>

Hey, now this part is making sense to me. I do understand that AC motors will draw more current when the voltage on them drops, and that they can burn out because of that. But we were only talking about a simple DC circuit... a battery, a switch, and a coil of wire (the solenoid). I'm pretty sure that Ohm's Law applies here. Lower voltage = lower current.

Anyway, thanks a lot for taking the time to discuss this with me. And thanks for asking about my tractor, but I'm not the original poster with the problem. I guess I'm just the guy who has hijacked the thread. /forums/images/graemlins/blush.gif /forums/images/graemlins/blush.gif

Tom