MF 65 Generator not charging correctly

[Rogerkmf50]

My MF 65 quit charging so I tested the 12 volt generator, and it tested OK. Then I put on a new voltage regulator and polarized it. Now the needle on my amp meter gauge swings back and forth erratically. Occasionally it will settle on "0" and move to positive when the throttle is advanced. Put overall it moves back and forth for no reason. Why? How can I get it to stop?
Roger

 

[Janicholson]

My MF 65 quit charging so I tested the 12 volt generator, and it tested OK. Then I put on a new voltage regulator and polarized it. Now the needle on my amp meter gauge swings back and forth erratically. Occasionally it will settle on "0" and move to positive when the throttle is advanced. Put overall it moves back and forth for no reason. Why? How can I get it to stop?
Roger

Somewhat depends on the quality of the regulator. Most of the less expensive variety have poor control. If the charging voltage is in the area of 14 I probably would live with it. If they take it back it would be a miracle. Jim

 

[Rogerkmf50]

Thanks. So you don't think it could be a bad or poor quality amp gauge?
R

 

[Hemmjo]

Thanks. So you don't think it could be a bad or poor quality amp gauge?
R

Did the Ammeter work correctly before you switched the voltage regulator?

 

[Janicholson]

Thanks. So you don't think it could be a bad or poor quality amp gauge?
R

If it "wiggled" before replacing the Voltage regulator, the gauge could be faulty. gauges (quality ones) have a drop of synthetic resin on the pivot causing them to be dampened, But it can become ineffective or gone. Trying a new gauge is OK, but using a test gauge in the wire to the starter switch from the existing gauge would assess the situation. The link is to a meter to test charging systems and starter draw. Nice to have, and if it wiggles it is the regulator if it just works, it is the meter. I have two of these meters from different companies, both work well. Jim

Thanks. So you don't think it could be a bad or poor quality amp gauge?
R

 

[Rogerkmf50]

If it "wiggled" before replacing the Voltage regulator, the gauge could be faulty. gauges (quality ones) have a drop of synthetic resin on the pivot causing them to be dampened, But it can become ineffective or gone. Trying a new gauge is OK, but using a test gauge in the wire to the starter switch from the existing gauge would assess the situation. The link is to a meter to test charging systems and starter draw. Nice to have, and if it wiggles it is the regulator if it just works, it is the meter. I have two of these meters from different companies, both work well. Jim

It was not charging so I did a motor test on the generator and it "motored". Plus I did an amp test with a multimeter and it was putting out 14+- volts. So I changed the voltage regulator (& polarized it) and it charged for about two/three hours then it quit charging. Then I changed the amp gauge, and "another" new voltage regulator. That is when it started wiggling, with the new gauge.
I've got other tractors with generators and none of then have gauges that jump around.
Roger

 

[Brownie450]

Polarizing the regulator may be causing your problems.
I always polarized the generator---not the regulator.
Jim

 

[Bob Bancroft]

It was not charging so I did a motor test on the generator and it "motored". Plus I did an amp test with a multimeter and it was putting out 14+- volts. So I changed the voltage regulator (& polarized it) and it charged for about two/three hours then it quit charging. Then I changed the amp gauge, and "another" new voltage regulator. That is when it started wiggling, with the new gauge.
I've got other tractors with generators and none of then have gauges that jump around.
Roger

I don't know if this would make a difference or not- I was surprised several years ago when working on a neighbors' 65, that MF installed a three brush generator with a voltage regulator as original equipment. You could try moving the third brush and see if it has an effect.
The quality of things anymore like voltage regulators, gauges, condensers, etc. make it difficult to do repairs.

 

[Janicholson]

Polarizing the regulator may be causing your problems.
I always polarized the generator---not the regulator.
Jim

Browniie has a point in that we don't know what you did to polarize a regulator (they do not get polarized) so the real issue is still quite unknown. An A circuit generator is polarized by the following. Engine stopped ignition off. Using a jumper connect battery non ground pole to the ARM terminal on the gen. this puts current through the field poles in the generator magnetizing the iron in the center of each pole. This magnetism is residual (stays there for years). It is responsible for the initial production of electricity when the generator starts to turn, thus voltage of the correct polarity is generated and brings the output up to charge the battery. An incorrect jumping of VR terminals could damage them. Jim

 

[Rogerkmf50]

The instructions that came with the VR (I've got them in front of me) explain it this way; jump between the BATT terminal on the VR and the GEN terminal on the VR. It only takes a second and a spark will appear. When you see the spark, your voltage regulator is polarized. All this takes place after the new VR is installed and the wires are connected properly.

 

[JMOR]

The instructions that came with the VR (I've got them in front of me) explain it this way; jump between the BATT terminal on the VR and the GEN terminal on the VR. It only takes a second and a spark will appear. When you see the spark, your voltage regulator is polarized. All this takes place after the new VR is installed and the wires are connected properly.

All that says is, "who ever wrote the instructions don't know jack!". It should read, "When you see the spark, your GENERATOR is polarized".

 

[Jim.ME]

The instructions that came with the VR (I've got them in front of me) explain it this way; jump between the BATT terminal on the VR and the GEN terminal on the VR. It only takes a second and a spark will appear. When you see the spark, your voltage regulator is polarized. All this takes place after the new VR is installed and the wires are connected properly.

Parts from the land of almost right may have almost right instructions, even right parts may have bad instructions, as here in your case. As has been posted the generator is what gets polarized. This can be done at the regulator for ease of access (more important on cars and trucks of generator vintage where you might have to stand on your head to reach a generator. That is what has led to some people thinking/saying the regulator is being polarized.

 

[Rogerkmf50]

Good to know. Thank you both.
Getting back to my original concern, I'm going to install a better quality AMP gauge to see if I can get rid of the wiggling needle.
Roger