8N 6v Generator rebuild?

Hammbone · Oct 31, 2014

Ok since I was doing this wrong apparently, the correct step is to take first wire with clips and attach from batt to arm at regulator? Next if there is still no charging I should leave the first wire connected and with a second wire at the generator connect between the field and ground studs. If charging begins regulator is bad. If still no charge, likely have a genny problem?

Soundguy · Nov 1, 2014

correct, the 3rd step is then to pull wires and motor test genny.

ground field and case, apply bat to arm.. see if it spins good.

if it passes that test. check armature wire in harness

Hammbone · Nov 2, 2014

So I believe the fields may be grounded out somewhere. I tried the regulator test again with no change, so I took the fan belt off the generator and the thing started spinning. I forgot to take the wire off of batt and arm, however I did not have to run a wire from field to he case. Does this mean my fields have grounded out somewhere?

Soundguy · Nov 3, 2014

Yes, no, maybee.

A good Genny may motor from residual field magnetism, however a full field yes with jumpers on all wires will tell

Hammbone · Nov 3, 2014

Soundguy said:
Yes, no, maybee.

A good Genny may motor from residual field magnetism, however a full field yes with jumpers on all wires will tell

I did also put a wire from field to ground with no change, genny continued spinning. What do you mean by a full field? And where does this leave the tractor, good generator, good regulator, still no charging?
Will a bad generator motor?

Soundguy · Nov 4, 2014

if the armature is good and the field is open, you can get a gen to motor from residual magnetism. generally one motors faster / stronger once you hook the field up. so if you hooked the armature to power and grounded the case and it motored immediately, but did not motor any faster by hooking field to ground, then i's suspect a field issue. PS. hooking field to ground is called 'full fielding' as it normally provides full field current.

you could try ohming field tab to case.. but without a real sensitive meter.. hard to gauge much unless it read open.

i'd pull the genny apart for a looksee.

field pieces are in the case, one side attaches to armature, the other to the field stud.

you may very well have an open field.

Hammbone · Nov 6, 2014

ok, I have the genny off the tractor and pulled apart. The fields (brand new) ohm out at 3.2-3.3 ohms, exactly what the fo4 manual states. The brushes are new , and the armature has been tested and had the comm turned down by an auto electric shop who said it was good. Am I putting this thing back together correctly? I reassembled it the way i took it apart, but that is assuming that it was put together correctly to begin with.... One wire from the field is connected to the insulated field stud, and the other is connected to what i was assuming is the ground stud since the two were marked F and G respectively.

Then on the back plate, one of the brushes is grounded directly to the case, and the other is connected to an insulated stud (armature correct?)

This looks to be consistent with an internally grounded type B generator..... Where do i go from here? (will update with pics shortly)

Soundguy · Nov 7, 2014

8N is type A not B

53+ gennies are type B

circuit A is with the fields to the insulated F terminal, and the armature.

circuit B is with the fields grounded and to the insulated F terminal.

An A type reg has the bias resistor between ground and field tabs

A B type reg has the bias resistor between the armature and field tabs, and may have an additional resistor present as well.

Hammbone · Nov 7, 2014

Soundguy said:
8N is type A not B

53+ gennies are type B

circuit A is with the fields to the insulated F terminal, and the armature.

circuit B is with the fields grounded and to the insulated F terminal.

An A type reg has the bias resistor between ground and field tabs

A B type reg has the bias resistor between the armature and field tabs, and may have an additional resistor present as well.

I believe a previous owner may have put a newer style generator here then, and may explain why the diagrams in the fo4 don't quite match up with what I have been looking at for the last month!! This is the way the fields are connected

one on right is insulated, one on left is uninsulated to case. Then the brushes,

again the one on the right is insulated to a large stud, while the one on the left is uninsulated to the case. Is this a 53+ model, or am I just not seeing this correctly? If you need me to take different pictures let me know what you need to see.....