Replacing 2030 Alternator - Wiring Question

bgsmith

New User
Update - I suspect I was mistaken that the two posts to the right of the field connection on the new alternator were both ground points. They differ in their connections to the body. But I do not know which is the ground and what the other post is for (probably orange wire?). Moving the post for the orange wire from the old alternator is not feasible. I should look more closely first.

I need to replace the old alternator on my 2030. This alternator is Deere part number AT21618 (picture below). There is green paint over-spray on the wiring which is a bit confusing but original wire colors are visible and wires are attached correctly.

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The replacement from Yesterdays Tractor (part number 115849; picture below) does not have a post for the orange wire and has, I believe, 2 ground posts. Yesterdays Tractor does not include a wiring diagram with the alternator, hence this post seeking help.

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Where should I attach the orange wire? This goes to the alternator lamp on the dashboard. I could attach as indicated by the circuit diagram below but the new alternator does not have the dual nuts present on the output and ground posts.

Another option would be to move the post for the orange wire from the old alt to the new (there is a threaded hole in a similar position on the new alt) but I do not know if this is correct and would work.

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thank you

This post was edited by bgsmith on 05/11/2023 at 12:02 pm.
 
Put the put the wire on the same stud in the new alternator ASSUMING there is enough thread to add a second (10-24) nut.

If you look closely, I don't believe there will be an insulating washer between the existing nut and the isolation diode plate, you can even put the wire terminal under the existing nut, if the stud is too short for an extra nut. CONFIRM ''no insulating washer'' before doing that, though.

The two studs on the left BOTH come from the (+) diode plate, the two studs on the right come from the (-) diode plate.

If you were to move the isolation diode plate you need to understand EXACTLY what combination of insulating washers and and a sleeve insulator are needed or you will make a dead short across the alternator through the diode plate and likely void the warranty once you take things off and move them around.

This post was edited by wore out on 05/11/2023 at 01:21 pm.
 
Thank you for taking the time to reply.

(quoted from post at 10:44:44 05/11/23)
The two studs on the left BOTH come from the (+) diode plate, the two studs on the left come from the (-) diode plate.

Did you mean to write that "the two studs on the right come from the (-) diode plate? I clarified in an update to the original post that I was mistaken that the two posts on the right side of the new alternator were both ground points. There are differences in how they are attached to the alternator body.

thanks
 
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Each pair of studs, the (+) on the left, and the (-) on the right connect INTERNALLY to their respective rectifiers.

The wire we are discussing connects to the output of the internal (+) rectifier and the alternator output is taken from the cathode of the isolation diode.

For are purposes here, we are NOT concerned about the (-) rectifier studs EXCEPT that in on the original alternator the isolation diode heat sink is INSULATED from the lower of the two (-) rectifier studs.

Since the isolation diode is located in a different area on the placement alternator that is NOT an issue, as neither (-) rectifier stud is involved.

This post was edited by wore out on 05/11/2023 at 01:22 pm.
 

GOSH, I hope I got the ''right and left'' posts straightened out now.

I was interrupted several times while writing the replay and messed up! SORRY!
 
You best thing to do is to get a one wire delco alternator,, you can get these at most auto parts stores for about $70,,this will eliminate the possibility of bad wires and bad voltage regulator.. the Motorola alternator that comes on those are faulty a system
 
(quoted from post at 06:28:42 05/12/23) You best thing to do is to get a one wire delco alternator,, you can get these at most auto parts stores for about $70,,this will eliminate the possibility of bad wires and bad voltage regulator.. the Motorola alternator that comes on those are faulty a system

Thanks Tim. Appreciate the idea and worth considering. I am not a mechanic, per se, much less knowledgeable about tractor/automotive charging systems. I agree that this set up with separate voltage regulator and alternator with 4 connections is more complex than, say, the simple plug on my Deere 1070. On the other hand, the old alternator and voltage regulator are likely original on this 1975 vintage tractor (I am not the original owner so cannot say for sure). Which says something about durability.
 

Thanks. Always glad when someone takes the time and effort to reply. I am constantly correcting myself to use "my other left" :)
 
I followed the layout Deere had in their tech manual for the tractor under the assumption that this aftermarket alternator would have the same layout for connections. Added a replacment voltage regulator and all seems to be working correctly. I appreciate all the help.

@wore out - Just enough room on the post for an additional nut and lock washer to hold the orange wire in place (goes to dash light).

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