Motoring a 6v generator as a test?

[redtom]

One of my 340 Farmalls quit charging. It had been sitting for 5 years or so and I got it running good but no charge. I've had this happen on other tractors sometimes I can stick a little flint paper in the gen and shine the armature and it will take off. This is all original 6v volt positive ground. I'm a stickler for keeping them as original as possible so I don't want any 12v conversions. My question is, will all generators motor? I disassembled this gen, shined the armature which is undercut, no bars were shorted to the shaft. The fields are not shorted to the case, brushes are long with good spring and free to move. This gen will not motor on the bench with ground (pos in this case) to field and hot to A term. (I found an older three brush gen on my shelf and it motors fine.) I put gen back on and still no charge. Am I missing something? I opened the regulator up and when I close the contact by hand it goes full discharge. I also tried polarizing the gen while running.

 

[old]

If all is as it should be yes they will

 

[Janicholson]

A gen will motor best if the field is not hooked up. There should be a direct connection from the F terminal to the A terminal Probably show an ohm or so with a sensitive meter. The Armature terminal should be near zero ohms to the gen case. The F connection supplies ground to the field through the regulator voltage control contacts. The Armature to ground connection through the opposite brush creates charging "out" the Arm terminal to the cutout, then from the cutout to the ammeter, then to the battery non ground, through the battery charging it to ground, and back to the generator housing. Jim

 

[Steve@Advance]

It should be polarized not running. Once everything is connected, jumper the A post to the nongrounded battery post. Only spark it, don't leave it connected. Do this before any further testing.

Then test the output. Ground the F post with the engine revved up to 1500RPM or so. It should show voltage increase across the battery.

If you want to try the motor test again, just take the belt off, disconnect the regulator leads, jump the nongrounded battery post to the A terminal, leave the F open. It should motor.

 

[redtom]

So, motor test should be, hot to A, but use chassis ground for F by having no wire on it but grounding the gen frame? Hmmm, my old 3 wire gen, motored with batt hot to A and ground batt post to F.

 

[tomturkey]

I believe I have 3 "red" generators on a shelf in the shop. The "magic" might still in them, but the "magic" in the cut-out/voltage regulators is illusive also. I'll be adding another "red" genny to the stack this spring. If you would like one of them, I think my e-mail is open. I am NO MAGICIAN, cannot make the needle read positive so I abandoned my big black hat and red gennies. gobble

 

[wore out]

Copy this link and paste it into your browser to access a good IH Blue Ribbon Electrical System Service Manual.

http://farmallcub.com/rudi_cub/www.cleancomputes.com/Cub/Blue%20Ribbon%20Service%20Manuals/GSS-1310%20Electrical/index.html

 

[John T]

Tom, here is the "Motor Test" portion of my Charging Troubleshooting Procedure, it should answer your question:

1) MOTOR TEST. You can Motor test the Gen. If its grounded and you remove the belt and apply hot battery voltage direct to its ARM Post and have the Field Post dead grounded to frame, it should motor n run well (Armature n Brushes and Commutator likely okay). Then, if you next remove the Fields ground and it speeds up some, the Fields "likely" good. If it passes BOTH those tests, it should charge, and if not, it may be a wiring or battery or grounding problem. The hot battery voltage may be taken off the VR's BAT terminal or the starter post or the battery itself for this test.

To be safe I would first POLARIZE as stated in my procedure:

2) To Polarize the Generator, first temporarily dead ground the Gens Field post to case/frame, then momentarily flash jump a wire from the Cutout Relay or VR's "BAT" terminal over to its GEN/ ARM) terminal and you ought to get a small spark. Same things accomplished by momentarily flash jumping a hot wire (BAT terminal on Cutout Relay or VR or starter post etc) direct to the Gens ARM post to get the spark.

Here is my complete Troubleshooting Procedure:

https://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=ttalk&th=2060825

Polarize,,,,,,,,,, run the motor test,,,,,,,,,,,,,run the other tests in my Troubleshooting Procedure,,,,,,,,,,post back any questions

John T
John Ts Troubleshooting

 

[Janicholson]

Some will do that, but they run easier when F is not grounded. Once running, grounding the F will slow it down substantially. This can indicate a likely good Field winding connection and continuity. Jim