Starter Generator Not Charging

[millerwelder]

Hi I have a 154 thats seems like the generator is not working. It has been rebuilt by me, coils tested for continuity, now rebuilt last week by an auto electric shop and it's still working exactly the same. It puts out ~1.5 volts at speed off the Main terminal without the voltage regulator connected, which seems right and then with the Main and F terminal connected to energize the field coil, it still produces 1.5 volts and not 12+. According to the article http://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=farmall&th=811423 this means the field coil is open. It previously tested for continuity by me when it was apart and I'm assuming the repair shop did also. Also I tested it by jumping 12v to the Main and then the F terminal to see if the field coil energizes and stops the armature, which it did. Shown in this nice video http://www.youtube.com/watch?v=bxTsANakLf8 So now I have misleading test results and was wondering if anybody has any idea of what might be wrong or what else to test.

[Eugene]

Does the starter/generator crank the engine over? If so the problem is or at the voltage regulator.

The rebuilder would have bench tested the S/G to make sure it motorized.

[millerwelder]

Yea it cranks the engine

[millerwelder]

Ok so from what I'm understanding is crossing the Main and Field terminals, rectifies the voltage up to 12 volts to charge and thats what the regulator controls. I took the cover off the regulator to observe it and it's doing nothing (as expected). I manually tried switching it anyway even though I've already tested this by jumping the Main and Field terminals on the generator and voltage doesn't go up. Also the contacts are clean. It just appears that the generator isnt working even though every other test shows it is.

By the way, I just got a cub cadet 102 that has the same system and I went to test it to compare to the lo boy and it does exactly the same things. Only difference is the generator will build up in the range of 2-4 volts like speced but the lo boy only gets close to 2. The generator on the 102 was also rebuilt 3-4 years ago by a shop and the tractor was charging at one time but since I got it, it doesn't.

[Eugene]

It just appears that the generator isnt working even though every other test shows it is.

Regulator problem. Ground, not wired correctly, or just plain faulty.

Manuals section, top of page, would be a good source of information on regulators and electrical systems pertaining to Cubs.

Alternators rectify AC current to DC. DC generators do not need to rectify the current.