alternator failure

[yosemite]

Hi
Another alternator has failed, cant work out why they are doing this
I have checked the unit out ,and again it is the field coil that is broken, literally. I have over the past ten  years or so replaced about ten of these and they all seem to fail in the same way,  Has there been something wrong with my engine all this time? I talked to a guy at an alternator/electrical rewind specialist a few years ago and he said that the problem was fairly common but they couldn't repair them as they couldn't get the rotor apart
  If I strip a unit down the broken wire is sometimes visible where the wire goes into the windings,near the commutator. Can anyone suggest a cure for this  reccurrent problem alternatively can any one suggest away to strip the rotor so I can rewind one (or two)
thanks
Paul
 

[racerman_27410]

i would be checking resistance on all the grounds really well..... especially that cable that runs from the battery negative terminal down to the back of the engine.

Mine had a bad crunchy spot inside the jacket.... couldnt see it but could feel it when flexing the cable.

probably a side effect of years of overcharging due to the laughable regulators... but anyway...

bad things happen when electricity doesnt have a good ground.


KOokaloo!

[JCainFJ]

 You also need to check the voltage to the alternator, the power feed to the field. If it is lower then the voltage at the battery you will have a problem.

[Pat Conlon]

Back in the old days, we had these things we called "slot cars" Rather than hanging out at a pool hall, we would hang out at the local slot car track, anyhoo...
To get more speed we would have the option to run higher voltages on the track and in doing so we would end up burning the windings on the motor armature....
To help resist burning, we used to encase the armature's copper windings in epoxy.
I wonder if that would help?

We have a new guy from San Diego, his name is Evan and he is a EE who specializes in this line of work.
http://www.fjowners.com/index.php?topic=5535.0

I will PM him and ask him to chime in with his opinion.

[andyb]

Back in the old days, we had these things we called "slot cars" Rather than hanging out at a pool hall, we would hang out at the local slot car track, anyhoo...

Of course we had to ride our wooly mammoths there, uphill through the snow, y`see... had to wear rocks because cloth hadn't been invented yet....

I'm proud of you for remembering back that far, Pat!  Those alzheimers meds are working well! 

[Pat Conlon]

Hey, at least we did have electricity...abet direct current.... Don't give me any shit, I'm having one of my few lucid moments...

[yosemite]

Hi
checked earths(grounds),all good, I also have an extra earth cable connection to bars engine and frame so I dont think it is a problem there
voltage to the field coil is same as battery voltage and changes with baterry voltage(used 2 meters to check)  brown field wire had to be temporarilly disconnected to do this. I also checked resistance betweem the brown field wire and the battery connection these was also good at 0.01 ohmso ther should be a low voltage drop when current is flowing to the field coil
  I suspect that it may be a regulator problem  If I can find a transpo or bosch regulator this side of the atlantic then I will modify as per the posts in the mods section
yosemite