might have pooched my alternator

[notfarnow]

I have an older style externally regulated alternator in my SC. About a month ago, I started getting low/sporadic voltage and a discharged battery, so I yanked the alternator and found the brushes were down to the nub. I took it to a local alternator repair shop and the replaced the brushes and it benched test fine afterwards

A couple weeks ago I notice the red light on the dash again, and sure enough I'm not charging anymore. Tonight I pulled the alternator and this is what I found:


It looks like there's been some arcing/scorching:





This is how I had it wired:


Did I have the thing wired wrong??

[timmy2]

Looks as though one of the brushes is not making good contact with the commutator. Could be the carbon brush sticking in the holder due to a weak spring.
The shop that replaced the brushes may not have shaped the brushes to the commutator properly and they have a high spot.

Check the wear pattern on the brush that has been arcing instead of conducting.

I would have the remote VR tested as well.

I'm assuming you had the black wire connected to the piece you have removed.

Wiring appears correct.

[Joe Bob]

Did you do the r&r on the brushes? If not, should be the alt guys dime. If not.....practice makes perfect.

Might want to have the guy look into an internal VR upgrade on your core.

[timmy2]

When I worked in a power plant on 100 megawatt generators one of the dirtiest jobs was replacing the carbon brushes. We used to have to shape them by sanding them to the contour of the commutator before installing so they would ride smooth or arcing/burning would begin.
Also, the type of brush materials was important. Too soft and they would wear away, too hard and they wouldn't wear correctly.
Something to think about, did they use the correct brushes?

[wwest]

Looks to me like maybe the slip ring is so worn down the brush is being shorted to the shaft at that point.