MEP-804a charred wire. No AC

[sigley89]

A buddy of mine picked up a genset (804). It runs fine but doesn’t send power down the line. After poking around we found a crispy black wire inside the control panel. See Photos.

Starts at the K5 block at the #6 terminal and goes to TB4-15.

A few questions:

what type of wire is this? The TM says is 16-14 AWG.

Can I use any 16-14 AWG or do I need this white/braided coating wire?

What would cause this wire to burn up?

Will replacing this wire fix the no AC issue?

 

[Triple Jim]

What would cause this wire to burn up?

Something that made it carry a lot more current than it was supposed to.

Will replacing this wire fix the no AC issue?

No, but fixing the thing that made it carry too much current probably will. That terminal on the relay is marked "AC", which implies that generator output is connected to it so it can sense when the voltage is too high or too low. If that relay has an internal problem that shorted the AC to ground, for example, it could burn the wire and maybe prevent generator output because of a false over or under voltage signal,

Someone familiar with that generator will probably be able to be more specific.

 

[sigley89]

when you say fixing the thing that made it carry too much current. Are you referring to what it was powering or something in the genset?

 

[sigley89]

That terminal on the relay is marked "AC", which implies that generator output is connected to it so it can sense when the voltage is too high or too low. If that relay has an internal problem that shorted the AC to ground, for example, it could burn the wire and maybe prevent generator out put because of a false over or under voltage signal

This is what I am thinking. I hope the previous owner was idiot and screwed it up. I hope we can just replace the wire and have it produced AC.

 

[fb40dash5]

when you say fixing the thing that made it carry too much current. Are you referring to what it was powering or something in the genset?

The charred wire is almost certainly not the problem, it's a symptom. Something put too much juice through it, causing it to get overheated.

I'd reckon that since the generator has safeguards to prevent overloading (and this wire is in fact part of one of those safeguards) the cause is something in the unit. What it is, I don't know (I am also quite unfamiliar with that model) but I'd be incredibly surprised if it weren't something.

 

[sigley89]

The charred wire is almost certainly not the problem, it's a symptom. Something put too much juice through it, causing it to get overheated.

I'd reckon that since the generator has safeguards to prevent overloading (and this wire is in fact part of one of those safeguards) the cause is something in the unit. What it is, I don't know (I am also quite unfamiliar with that model) but I'd be incredibly surprised if it weren't something.

Well in the spirit of saving information for future readers I’ll replace the wire and see what happens. Might get to it this Saturday

 

[Triple Jim]

This is what I am thinking. I hope the previous owner was idiot and fucked it up. I hope we can just replace the wire and have it produced AC.

That's not what I meant at all. I was guessing that the relay unit has an internal problem that shorted AC to ground (as an example), causing that wire to overheat. Wires don't go bad and burn, so that replacing them fixes the problem.

 

[Triple Jim]

when you say fixing the thing that made it carry too much current. Are you referring to what it was powering or something in the genset?

Something inside the genset. That wire does not carry generator output current to the output lugs.