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190XT New "Old" Alternator not charging

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Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=210647
Printed Date: 06 Apr 2026 at 10:43am
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Topic: 190XT New "Old" Alternator not charging
Posted By: MadCow
Subject: 190XT New "Old" Alternator not charging
Date Posted: 05 Apr 2026 at 5:46pm
My 190xt had a new one wire alternator put on it. Since my distro tach drive is stripped I opted to go back to the alternator tach drive. Bought the old style which I guess is actually the second or new style? Whatever. Bought the 3 wire tach drive alternator from DJs. But I cannot get the alternator to charge. I'm 99% sure the wires are making solid connections on everything that is connected, and I *think* everything is wired to match the service manual. Problem is the service manual only shows for the delcotron not for an alternator?

I don't hear or see any clicking from the voltage regulator. How is this thing supposed to be wired up? How can I test the voltage regulator? The service manual read like gobbldegoock.




Replies:
Posted By: jaybmiller
Date Posted: 05 Apr 2026 at 6:29pm
To me that looks like an alternator with built in voltage regulator. A '3 wire' unit and not 'one wire'.
For me
 a 'one wire' unit ONLY has the big , high current wire
 a 3 wire has, high current, a sense line and an ign wire.

Either of which do NOT require that external  regulator



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3 D-14s,A-C forklift, B-112
Kubota BX23S lil' TOOT( The Other Orange Tractor)

Never burn your bridges, unless you can walk on water


Posted By: MadCow
Date Posted: 05 Apr 2026 at 7:05pm
I think this is 3 wire. So how do I "bypass" that external reg?

I have the jumper going from power to the 'field' or regulator plug port. Should the second wire go straight to ground?

I tried all sorts of other configurations and couldn't get any charge.


Posted By: KJCHRIS
Date Posted: 05 Apr 2026 at 7:23pm
That is a Delco DN series Alternator w a mechanical tack drive. mounted to it, not sure on the regulator.   
  FYI; There are 2 Voltage Regulators that work with the DN alternators. 
  1 for an Idiot light. AND 1 for an Ammeter. IF wrong Reg is used the Alt won't charge. 
  Left wire (orange) on Alt is live at all times and goes on that left insulated terminal. 
   FYI, I'd remove the short red wire. 
Where you have red wire plugged in ("F" term) should be a wire (light green) plugged in, it comes from the #1, Left hand terminal on voltage regulator. 
 The far-left wire on Alt is a ground wire. 
 You should hear / or feel the regulator click in when the ignition switch is turned to the RUN position. 
 Voltage Regulator terminals; left to right, must be grounded.  
 #1 term on V Reg is wired to "F" field Term on Alt. Live when ign sw is in run. 
 #2 term on V Reg is wired to ign sw terminal that is on in the run position. ign sw ON.
 #3 term on V Reg is wired to the Battery Cable stud on Starter Solenoid. Always live.
 #4 term on V Reg is not used. 



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AC 200, CAH, AC185D bareback, AC 180D bareback, D17 III, WF. D17 Blackbar grill, NF. D15 SFW. Case 1175 CAH, Bobcat 543B,


Posted By: steve(ill)
Date Posted: 05 Apr 2026 at 7:32pm
agree it looks like a DN alternator , so has an external reg.... look at the paper work and see if that is what you bought...





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Like them all, but love the "B"s.


Posted By: MadCow
Date Posted: 05 Apr 2026 at 7:43pm
I got it from DJs

This one:
https://stores.djstractorparts.com/55-amp-alternator-w-gear-box-for-tachometer-allis-chalmers-d21-170-180-190-200-210-220-70245330/?searchid=0&search_query=70245330" rel="nofollow - https://stores.djstractorparts.com/55-amp-alternator-w-gear-box-for-tachometer-allis-chalmers-d21-170-180-190-200-210-220-70245330/?searchid=0&search_query=70245330


Alternator 400-12376 is all the paper says.


Posted By: MadCow
Date Posted: 05 Apr 2026 at 7:45pm
Do you know which reg for ammeter I need? I would think the reg that was on it was right?


Posted By: steve(ill)
Date Posted: 05 Apr 2026 at 7:47pm
well since it says "replaces original"... i would guess they assume your using the external regulator.... couple drawings related to what Chris said....





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Like them all, but love the "B"s.


Posted By: MadCow
Date Posted: 05 Apr 2026 at 8:02pm


Ok. Wired like this.

The big wire goes to ammeter.

The "F" green wire is original wire harness and connects to the "1" post on Vreg. I've tried in both plugs, there is no marking which is 1 or F. Left it as shown in picture, left plug. The wire is good, makes noise when connecting the meter to both ends.

VReg body is grounded, there is a strap connecting the body to the mounting post and I meter verified it is grounded. There is a spade terminal that isn't connected to anything that is NOT one of the front 4, it's on the side of the VReg, does that need to be grounded separate?

Wire "2" on Vreg goes to the ignition switch. I have a push pull two position switch. It's connected to the open side and connects to 12+ when switch is closed and ignition on.

Pole 3 at Vreg is 12+ always, connected to starter solenoid.



Posted By: MadCow
Date Posted: 05 Apr 2026 at 8:06pm
There is no clicking and the VReg doesn't do anything switch on or off, engine running or not, bad solenoid coil in the reg?

The third wire, that little post on the Alt. Whether I plug that boot in or not doesn't change anything.

When I switch lights on I drop to 11.8v, and ammeter shows draw. Lights off I'm back to 12.3v but NO charge.


Posted By: MadCow
Date Posted: 05 Apr 2026 at 8:07pm
Also I have double verified that I get very few mohm resistance in all the wires from one end to the other. So I'm confidence it's not a bad wire that I'm using.


Posted By: Jim.ME
Date Posted: 05 Apr 2026 at 8:36pm
That is a Delcotron (Delco's name for the alternators) model 10DN externally regulated alternator.

Looking at the back of the alternator, the F (field) terminal is the right spade.  The R (reference aka sensing) terminal is the left terminal.  

You can test the 10DN alternator by using a jumper wire between the Battery terminal and the F terminal to apply power to it.  This will full field the alternator and it should give you full output power.  Don't run it long that way.

Do not ground the Field wire from the regulator as it supplies power to the alternator field and grounding it can damage the regulator.

If you are trying to use the old regulator, it may be bad.  1. Test the alternator output. 2. Use a test light or voltmeter to test for power from the regulator to the alternator's F terminal.  If the alternator test ok and you don't get power from the regulator, you need a new regulator.  Steve at B&B can confirm, but I believe there are some electronic ones now that might be a replacement for the old ones with mechanical points.






Posted By: SteveM C/IL
Date Posted: 05 Apr 2026 at 8:57pm
THE EXTERNAL REG SHOULD CLICK WHEN ENERGIZED


Posted By: TedN
Date Posted: 05 Apr 2026 at 10:41pm
Transpo makes a regulator called a star II that effectively turns the 10dn into a one wire alternator. It mounts to one of the case bolts and has four connections; the 12v positive and negative and the field plug. I used one for many years(33 if my math is correct) on my 190XT until the insulation on the wires degraded so much I began to worry about an electrical fire.
https://ebay.us/m/sAxHvL" rel="nofollow - https://ebay.us/m/sAxHvL

Edit - I just looked a little closer at the link I posted. It is a 24v regulator, most of them are 12v but look before you buy.

I am not going to recommend one unless you are really stumped though because they always have a slight draw on the battery. I had to have a battery shutoff switch or it would die after a week or so.
When I changed it out I went back to running a regulator hooked into the original harness. The electronic unit I bought is also from Transpo.
https://a.co/d/03ztzofq" rel="nofollow - https://a.co/d/03ztzofq
I am not saying that Transpo products are the best, just that I have used them and have had good service life with them.
I did run an extra ground to the side terminal on the regulator, but if I remember correctly it wasn't needed, but I put it in as I was wiring in an auxiliary power relay so I had the extra ground in the area anyway.

Ted

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190XTD seriesIII, 190XTD seriesI, maroon belly 7000, 190XTD series??? project(or maybe parts)


Posted By: MadCow
Date Posted: 06 Apr 2026 at 9:19am
I'm gonna grab a new reg and give it a go, no clicking is a tell tale I think. Probably a bad solenoid.

Ted, is that Amazon link one you used and it still draws? Won't want to hassle with a battery disconnect on this tractor.


Posted By: TedN
Date Posted: 06 Apr 2026 at 9:36am
The one from Amazon goes in place of the original, so it is shut off with the key switch, and doesn't draw the battery down. I put it on three years ago and it still works, so I'm happy with it.

Ted

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190XTD seriesIII, 190XTD seriesI, maroon belly 7000, 190XTD series??? project(or maybe parts)



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