MF 65 not charging

Boss Hog

Member
I'm working with an MF65 gas that belong to my Dad. Due to his age, he's now in town and I'm taking care of things at the farm.

I recently discovered the thing isn't charging, and am not sure what's wrong. Since this has a generator and voltage regulator just like a 35, I figured you guys were more likely to know something about this than over at the MF forum.

I found a set of instructions on a "N" forum. Tried to link to them, but for some reason the website filter thinks the link contains swear words.


I tried flashing the field and grounding the field terminal. All I got was a bunch of sparks. Nothing I did changed the voltage or made the ammeter move. Since none of the terminals are labeled, I might have hit the wrong thing.

Just for the heck of it, here's a picture of the voltage regulator with the cover off:

Voltage%20regulator_zps5qitqoio.jpg



I tried cleaning the points. While the tractor was running I also tried pushing on the tabs to make contact. That didn't change the charging rate at all.


I don't know where to go from here. I'm wondering if the voltage regulator is fried, but have no clue how to tell.

The tractor is obviously old. Maybe the brushes in the generator are work out? I looked to see if I could buy those in the parts section of this website, but didn't find them.


If you can offer any help I'd sure appreciate it.
 
If you dig back enough there is a way to test the Genny. You hook
it to a battery and its supposed to spin. I'm not sure on
particulars.
 
Quick check with the engine about 1000 RPM is to ground the generator field terminal, if it charges the generator is OK and the regulator needs attention. Another check is with the belt off, jump the battery hot post to the armature generator terminal, it should run like a motor, but not fast. Might be simple as freeing up stuck brushes..
 
Tried grounding the field terminal, and got no response.

Never heard of trying to make the generator run like a motor.

I haven't checked the brushes yet. Will try to do that tonight.
 
When grounding the field, bring the RPM up to around 1500 or so.

Best to put a volt meter from the armature terminal to ground, watch for the volts to start climbing. If no increase, the generator is not working.

If voltage does climb at the generator, move the volt meter to the battery. If no voltage climb there, the regulator or wiring is bad.

You can open the generator, look for obvious problems, worn, dirty brushes, broken springs, broken wires. Look at the commutator, all the segments should be the same color. If any are black, the armature is shorted.
 
I did more or less as you described last night. Nothing I did changed the voltage. Although I only checked at the battery.

Tonight I disconnect the generator and hooked a jumper to the battery terminal. It spun up like a weak electric motor.

So it's looking like the voltage regulator is bad.
 
Got a new voltage regulator in the mail this morning. Put it on this afternoon, and it's charging normally.

Many thanks to you guys who made suggestions. I appreciate the effort.
 

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