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420 U generator problems

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Dave Gardiner

03-17-2003 11:29:40




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The original 6 V generator was not chsrging so I bought a rebuild kit disassembled cleaned, trued up the armature installed the new parts. When I installed the Gen I sparked the A terminal before starting. The Gen shows a discharge that increases with RPM. I disconected the leads and tried to have the Gen motor by appling battery voltage to the A terminal, the shaft tries to turn but will not pull it self. What test can I run at this time to figue out if its the winding or some other problem.

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Ray

03-17-2003 16:40:13




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 Re: 420 U generator problems in reply to Dave Gardiner, 03-17-2003 11:29:40  
Most of the time it's the voltage regulator.I
worked on two last week regulators fixed both.
Generators just usually need cleaned out,also
old rotten wires can cause a problem.Not much
there,2 wires to the regualtor,Armature,field.
The battery wire goes up to the dash fuse,a wire
from there to the switch.I usually just take
generators to a local repair shop,for $25.00 they
rebuild,turn armature,install new brushes,saves me
a lot of problems.The regulators cost me $40. though.

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Clooney

03-17-2003 12:48:48




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 Re: 420 U generator problems in reply to Dave Gardiner, 03-17-2003 11:29:40  
Dave, turn the lights on or the ignition on to see if it shows a charge, if so your ammeter is wired backwards & the generator is really charging. Your tractor came positive ground from the factory.
~If that's not the problem, make sure the generator isn't charging backwards. How did you spark the A post? [you need to momentarily run power to it].
~On the not motoring, make sure you are running a big enough battery source to it [a battery charger probably isn't enough]. If it is a 3 brush generator make sure the 3rd brush is as close as possible to the power brush.
~If all the above checks out ok use an ohmmeter & check for shorts between the commutator segments & the armature shaft then check for shorts from the field coils to ground. ~Try motoring the generator with the {F} post shorted to the generator case to see if some field magnetism will get it to motor, then once motoring remove the {F} post short to ground & see if it picks up speed.
~If nothing shows up per the above you probably have a bad generator armature [you really need a growler to test it], or a short internally ...
~Post back with more questions as they come up.....

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