john deere 750 alternator

arbtmn · Aug 23, 2018

Hello. I am having trouble with figuring out my alternator on the JD 750. I just ordered a new one and put it on the tractor. idental to the 2 wire alternator I took off. Well it is still not chargine the battery. I also replaced the Voltage regulated. Question. Does it matter which wires go into the two wires coming out of the alternator? I mean in any specific order? I plugged the two wires from the harness into the new alternator. Should there be another wire running to the battery somewhere? I can't see how 2 wires from the alternator to the 2 wires of the harness ends up charging the battery

Bob · Aug 23, 2018

Those little alternators are simple permanent-magnet units that output 28 Volts AC (nominal) which is rectified and converted to a regulated DC battery charging voltage by the rectifier/regulator.

They work just like the under-flywheel alternators on small air-cooled engines.

Since the alternator output is AC, it doesn't matter in what order the leads are connected to the alternator.

Begin by checking for around 28 Volts AC at the output leads with the engine running above slow idle.

How many connection tabs does the regulator have? Are they labeled?

There's gonna be 2 for the AC from the alternator to enter, probably one for the charge indicator light, one for the charging current to output, perhaps a ground, etc..

Is the connector burned or damaged at the regulator (common)?

Is there a fuse after the regulator?

arbtmn · Aug 23, 2018

Thanks for that Bob. Ok - well my volt meter was on DC voltage to check the output. I will switch to the AC readings. Now I also know thank to you that the 2 wires coming out of the alternator are ac and can be connected in any order. After connecting the 2 wires to the 2 harness wires that were connected to the old alternator I started her up. Well as it was running my red alternator light remained on - and this is with the new voltage regulated. When I replugged in the OLD VR the light did not come on while the engine was running. I suspect the NEW VR is telling me the truth and the battery is not charging. I do have fuses after the regulated and I will check those. I will get back to you with what I find out. Thanks for your input!

arbtmn · Aug 23, 2018

I think there are 6 wires on the VR leads but I will check. They are not labeled

arbtmn · Aug 23, 2018

I may unwrap the harness and see exactly what is what. I am also thinking about making my own instrument panel with simple automotive gauges. Would this work?

john deere 750 alternator

arbtmn

Member

Bob

Well-known Member

arbtmn

Member

arbtmn

Member

arbtmn

Member

Similar threads