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Gentlemen,

I recently became the proud owner of a late '60s JD 1020 diesel. It's a really great little tractor and gives me all of the muscle I need to bush hog and clean up the 150 acre tobacco/soon to be timber farm my wife recently inherited in Southern Virginia.

Since I purchased the tractor I've changed the oil and oil/fuel filters, and put a fresh coat of paint on a number of parts. It works great, except that the battery doesn't seem to be getting a charge from the alternator (the alternator light is on and I have to charge the battery before each use).

I purchased a new alternator that is supposed to be a universal fit for JD tractors, but when I went to install it the other day, the leads on the old and new unit didn't match, so I wanted to consult the experts before I screw something up.

Below is a link to a picture of the new and old alternator.
alternator | Flickr - Photo Sharing!

If I were the guessing type I'd say all of the positive leads go on the big terminal and the negative goes to the little terminal, but I'd love confirmation before I wire it up.
 

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I moved this to the proper section. As to your question, I have to leave that up to the other members here.

:wgtt:
 

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The original alternator was a motorola with an external voltage regulator. I don't have any experience converting to the style alternator you have which appears to have a built-in regulator. The original style motorola is still available and is what I always use. I feel sure you would need to unhook the original regulator and do some rewiring to make the charge light still function. The place that sold the "universal" alternator didn't offer any instructions? Hopefully, someone here will recognize the newer alternator and will be able to offer some pointers.
 

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On your old alternator, starting with the double large red wires. These are the positives. One goes to the starter solenoid and the other to the ignition switch. Going clockwise, next is output (orange?) to voltage regulator. Next (green?) is field, goes to voltage regulator. Last (black?) is ground and goes to voltage regulator.

On the new alternator, above the largest stud it looks like there is a +B. So that would be the battery wires (two red wires). The picture is not clear enough to tell the markings for the other terminals.

My GUESS is the smaller stud is output to the voltage regulator and the 1/4" male blade terminal is the field connection and there is a non insulated stud that is the ground.

Post up how these terminals are labeled.
 

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Do you know if it has a built in regulator?
Have you had the old one tested? You may just need a regulator, or fix a broken wire/bad connection.

My GUESS is the same as before, small stud is out put to regulator D+ and the blade is the "Field" to the regulator ("W" might mean windings).
 

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Discussion Starter #7 (Edited by Moderator)
Do you know if it has a built in regulator?
Have you had the old one tested? You may just need a regulator, or fix a broken wire/bad connection.

My GUESS is the same as before, small stud is out put to regulator D+ and the blade is the "Field" to the regulator ("W" might mean windings).
I don't know if the new one has a voltage regulator or not. Below us a link to the description provided by the seller:

http://item.mobileweb.ebay.com/viewitem?itemId=151022726701&index=10&nav=WATCHING&nid=23379897123
 

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From the link to ebay . in the table, for regulator it says IR. I take this to mean internal regulator.

The two large red wires will connect to the B+ terminal.

You need to trace the wire from your alternator and find the one that goes to the alt indicator light. It should be the orange wire. Connect it the D+ terminal. The other wire at the alt indicator light should go to your voltage regulator. Disconnect your voltage regulator. You need to find which wire goes from your voltage regulator to the ignition switch. It will have 12 volts when the key is "ON". Connect these two wires together.

Your alt light will NOW have two wires going to it. One from the alternator D+ terminal. The other from the ignition switch (it will have 12 volts when the key is "ON") The way this works is when the key is "ON", but the engine is not running, the alt light will get 12 volts and be "ON". When the engine is running, and the alternator is sending MORE than 12 volts to the indicator light, the 12 volts from the battery cancels 12 volts from the alternator and the remaining voltage from the alternator (say it is 15 volts minus 12 volts equals 3 volts) is not enough voltage to light the alt indicator light. If the alternator belt breaks or the alternator fails the indicator light no longer gets any voltage from the D+ terminal, then the 12 volts from the ignition switch causes the alt indicator light to come "ON"

I don't think you need to connect any wires to the W blade terminal.



That should be it.
 
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