How to check generator output?

Sat Mar 07, 2009 11:34 pm

Hi fellas. It's been a while since I've been on here. It's good to see that the board is growing and doing so well.

I need to pick your brains on an electrical problem. My cub is a 1957 model. I've got the standard 6v positive ground system. I restored it (with lots of help) a couple of years ago. I had the generator overhauled and installed a new wiring harness and voltage regulator. About half way through the first season it stopped charging reliably (became intermittent). It seemed that sometimes a little "whack" to the voltage regulator would make it start charging again. At the beginning of last year, I bought another regulator - thinking maybe I just got a bum one. It worked for a while but now does the same thing.

I doubt that two regulators would be bad. So now I'm thinking maybe generator. I took the generator off yesterday. I cleaned the contact points between the gen frame and the tractor so that the ground would be good. I also took some light grit sandpaper to the armature. After putting it back on (and polarizing) still no charge. How can I isolate the generator and check its output? The manual has some info, but I don't have any test equipment other than a digital multimeter.

The ammeter works correctly, and I've verified that the system is indeed not charging. The voltage across the battery is no different when the tractor is running or dead, and the tractor dies immediately when I disconnect the battery.

I appreciate any and all help.


Re: How to check generator output?

Sat Mar 07, 2009 11:46 pm

There have been several discussions in the recent past concerning the poor quality of the lower priced voltage regulators. Here is a trouble shooting flow chart, courtesy of FarmallBob


Re: How to check generator output?

Sun Mar 08, 2009 8:44 am

If you ground the generator F terminal the regulator circuit is bypassed and the generator will go to full output. If it does not, you have a problem in the regulator circuit. As John said, there are a lot of failures with the cheaper regulators. Spend the money for a good one.

Re: How to check generator output?

Sun Mar 08, 2009 9:33 am

That is an awesome flow chart....don't get any easier than that......oh wait....Unless someone else fixes it for ya while you watch.
Robert (likes time change but tired) Miller

Re: How to check generator output?

Sun Mar 08, 2009 9:10 pm

Thanks John and Bigdog. I knew y'all would come through. That flow chart was exactly what I needed. Turns out I had a bad ground. It took me a while to isolate it, but it was between the mounting plate for the regulator and the engine block. I had brightened up the metal around the holes in the plate, but apparently the rest of the paint was stopping the metal from touching, and the bolts must have been right through the center of the holes and not touching the sides. I made a thin little washer out of some .020 aluminum I had, and that fixed it right up. It even charges with the lights on now ( at least on low, on high it's a very small discharge).

Thanks again. I hope everbody is doing well. It's time to change the oil and get it ready for mowing season!

Re: How to check generator output?

Mon Mar 09, 2009 11:13 am

Bigdog is right about bad regulators, the first 2 I bought were bad out of the box. The more expensive MADE in USA one works great