alternator

gbs · Mar 1, 2021

we have sprayer with a jd engine that originally had an alternator with an electric tach signal connector that someone converted it to a one wire 10si delco without the tach signal connector. does anyone have an internal wiring schematic for a 10si with a tach signal connector or can explain how it is wired internally as I would like to be able to hook the tach back up with out replacing the alternator. the 6.2 gm diesels used them but I can't locate any wiring info.

Steve@Advance · Mar 1, 2021

You will need to open up the alternator.

Once open, you will see a row of 3 nuts where the stator windings attach to the bridge rectifier.

Remove one of the nuts, any one, and attach a small wire, use a solder eye connector. Tie and tuck the wire down so it can not come in contact with the rotor. Extend the wire out through the back of the case wherever there is a convenient opening. A dab of silicone will keep it from rubbing on the case.

This will be your tach signal wire.

PS: You do know the trick to hold the brushes in with a toothpick or paper clip through the hole in the back? Note the clock position of the cases, as they can go back in 4 positions.

wore out · Mar 1, 2021

(quoted from post at 20:36:18 03/01/21) we have sprayer with a jd engine that originally had an alternator with an electric tach signal connector that someone converted it to a one wire 10si delco without the tach signal connector. does anyone have an internal wiring schematic for a 10si with a tach signal connector or can explain how it is wired internally as I would like to be able to hook the tach back up with out replacing the alternator. the 6.2 gm diesels used them but I can't locate any wiring info.

Inside the alternator there are 3 terminal studs on the rectifier, one for each "phase lead" from the stator.

If you are capable of opening up the alternator and successfully putting it back together including restraining and releasing the brushes as needed you can thread a lead wire inside to any one of those terminal studs on the rectifier, that will give you the AC signal the electronic tach is looking for. Use a couple of dabs of silicone sealant to keep your new wire out of trouble with moving parts inside the alternator and vibration.

If the pulley has been changed to a different size, obviously the tach won't read correctly.

(POSSIBLY if the original alternator was some brand other than Delco the number of rotor poles MAY be different, casing an incorrect reading, as well, there's a good chance of no issue there.)

If you want to get fancy, kits are available to install a stud like the factory did.

The stud kit installs in an existing hole near the alternator's output connector.

gbs · Mar 2, 2021

Thanks for the replies that's an easy fix, as I would like to stay with the declo 10si, also the tach is an adjustable one.

matthies · Mar 2, 2021

Like Steve mentioned about the four positions, now is the time to place the rear half in the correct position for your application, just in case the pigtail is out where it can get bumped/hit.

alternator

gbs

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Steve@Advance

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wore out

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gbs

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matthies

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