neg. pos. ground
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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=27966
Printed Date: 28 Feb 2025 at 4:00pm
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Topic: neg. pos. ground
Posted By: Josh(NE)
Subject: neg. pos. ground
Date Posted: 26 Mar 2011 at 9:15am
Is there a shur way to tell the difference at a glance. Or should I say an easy way to tell. Thanks
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Allis Express
'65 190XT, 37 B, '72 170, '83 8030, and the IH 560 was a mistake
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Replies:
Posted By: Scott(GA)
Date Posted: 26 Mar 2011 at 9:22am
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Josh,
Wouldn't the ignition coil leads be the key to this?
Best regards,
Scott
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Posted By: CTuckerNWIL
Date Posted: 26 Mar 2011 at 9:51am
Look to see which side of the battery is connected to ground + or -. If it has a distributor ignition the distributor side of the coil would be the "ground". The coil will have + and - mark on the terminals.
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http://www.ae-ta.com" rel="nofollow - http://www.ae-ta.com
Lena 1935 WC12xxx, Willie 1951 CA6xx Dad bought new, 1954WD45 PS, 1960 D17 NF
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Posted By: Scott(GA)
Date Posted: 26 Mar 2011 at 10:13am
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Ha! I was assuming that the battery was gone but I guess I shouldn't have done that.
Best regards,
Scott
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Posted By: Gerald J.
Date Posted: 26 Mar 2011 at 10:54am
Look at the connectors for the battery. Big and small posts are supposed to be a hint of polarity. If you can only bang the little one on half way its on the wrong post and if they big one rattles on the little post, its on the wrong post.
The coil terminals should match the battery terminals for best running and the ammeter should read discharge with a battery hooked up and the lights on with the engine not running.
If it has an alternator positive ground will probably let lots of smoke out of the alternator and maybe the battery.
After you choose your battery polarity and adjust the ammeter and the coil to match, you MUST to flash the generator to be sure it generates with the proper polarity BEFORE STARTING THE ENGINE or you can destroy the cutout/voltage regulator and the generator. If the generator has been to a generator shop, or has been setting a while its just as important to flash the generator.
The vintage starter spins the same direction with either polarity so its not a test.
Radios with reversed polarity tend to smoke and not to work.
Gerald J.
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Posted By: 49WF
Date Posted: 26 Mar 2011 at 11:01am
what is meant by flashing the generator?
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More than I need
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Posted By: GregLawlerMinn
Date Posted: 26 Mar 2011 at 12:10pm
Another term is "polarizing" the Voltage regulator. Don't know if it is necessary for a 6V with a cutout relay.
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What this country needs is more unemployed politicians-and lawyers.
Currently have: 1 D14 and a D15S2.
With new owners: 2Bs,9CAs,1WD,2 D12s,5D14s,3D15S2s, 2D17SIVs,D17D,1D19D;1 Unstyled WC
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Posted By: Josh(NE)
Date Posted: 26 Mar 2011 at 12:34pm
On my 190 and my 170, which both have alternators, one has positive to points from coil and one has negative to points from coil. I've seen a lot of tractors that were reversed, not sure what difference it makes. Wiring diagrams in the service manuals don't stipulate which side of coil goes to points. Were all D series tractors originally negative ground? How exactly step by step do you flash a generator?
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Allis Express
'65 190XT, 37 B, '72 170, '83 8030, and the IH 560 was a mistake
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Posted By: Gerald J.
Date Posted: 26 Mar 2011 at 1:16pm
Flashing or polarizing a generator IS IMPORTANT for all generators whether with cutout alone or with voltage regulator (the voltage regulator box always includes a cutout). A generator builds voltage when spinning from residual magnetism in the field poles. That can be lost from testing at arbitrary polarity on a test stand, or vibration, or just sitting unused. Then it may not build at all or may build with the wrong polarity. And having a battery sitting there with -6 volts (positive ground) and a generator building to +7 volts when the cutout closes both get shorted and the cutout is the first to go, followed by the generator brushes and commutator.
Flashing or polarization techniques depend on the wiring and controls and so are a bit specific to a particular machine. In general you apply battery voltage to the generator by jumping the battery and A terminals on the voltage regulator or cutout, but you have to know the field is connected (which it may not be with some charging control switches) or the exercise is futile. Its the field that needs the polarization, the armature doesn't benefit from it. That's a good reason to OWN a copy of the tractor operator's manual among many other tidbids in that manual on safe and effective use of the tractor.
Gerald J.
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Posted By: Gerald J.
Date Posted: 26 Mar 2011 at 1:18pm
Ignition coil polarity backwards won't prevent an engine from running, but the effectiveness of the spark at good ignition comes with the coil polarity matching the battery polarity, to put a particular polarity at the plugs.
Gerald J.
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Posted By: wbecker
Date Posted: 26 Mar 2011 at 1:37pm
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Delco generators are "A" system, that is the field is grounded in the generator, gets power from the regulator.
To polarize an "A" system:
if it has a regulator, momentarily touch a jumper wire from the Field terminal on the regulator to the Bat terminal on the regulator.
If it has a cutout, remove the cut out cover and momentarily close the points.
What you are doing is magatizing the field magnets in the generator to the correct polarity.
If you have a "B" system (Ford type), Diconnect the Field wire at the regulator and momentarily touch the Bat terminal on the regulator.
Bill B
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Allis B, IB, Low B, G, D10, JD M, 8KCAB, C152
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