My Tractor Forum banner

1 - 5 of 5 Posts

·
Master Service Technician
Joined
·
748 Posts
Discussion Starter · #1 ·
SIDENOTE: I have worked on Lawn and Garden equipt for the past 30 years.

I Inherited a 1953 8n 6 volt system-with a side mount distributor. The tractor sometimes charges and sometimes does not based on my ammeter. The Generator belt has been replaced and it properly tightened.

I have noticed that when driving on the road in 4th gear at full throttle it will charge,(less then 5amps) but when driving normal in the yard in lower gears at lower RPM's it will not charge.

I have confirmed the above findings at the battery with a Digital test meter.

Im trying to figure out if its the generator, regulator or wires in between.

Is there a way to get a voltage reading off the Generator? And what should it be?
 

·
Retired - Veteran Mod
Joined
·
6,791 Posts
Not really sure about which piece of your charging system is failing...

Wires are relatively easy to check... and easier (and cheaper) to replace, so... I'd start out with them. Check them for continuity... and resistance. Pay particular attention to the connectors... places were corrosion (and its inherent resistance) can build up.

The regulator would be the next "least expensive" item. Check the contacts, make sure that they're all clean and tight (both internal and external contacts).

You should be able to disconnect the regulator... and get "output voltage" from the generator (6V-8V), momentarily, which should help you determine if the generator is working or not.

On a side note... if your tractor is a 1953... then it's an NAA Golden Jubilee. If it's an 8N... then it can be no 'newer' than 1952. 8Ns were made from 1948 - 1952.
 

·
Premium Member
Joined
·
5,674 Posts
My best guess is the regulator but follow what Steve said about the wiring. After you are sure the wires are clean and tight you can "full field" the generator and if it charges then I would change the regulator.

If you do have a late 8N or even an NAA then the charging circuit is a "B" type and you would apply battery to the Field terminal to "full field the generator.
 

·
Master Service Technician
Joined
·
748 Posts
Discussion Starter · #4 ·
"Full Field the Generator" Please explain?
 

·
Premium Member
Joined
·
5,674 Posts
I did, may be just not good enough, it is a way to test the generator output. It makes the generator put out the max charge to its capable of producing and if you see it is charging and within spec then the regulator is probably bad since it is what controls the generator output.

If yours is a late model like you say then it is a 'B' type circuit (provided someone did not change things), that means the regulator controls the generator output by controlling battery voltage applied to the 'FIELD' terminal, more battery, more charge. That is why you use a jumper and apply full battery voltage to the 'FIELD' and see what the genny does. Now the older 'N's had an 'A' type circuit, it controls the output by controlling the 'GROUND' applied to the 'FIELD' terminal. Obviously you need to know which type you have in order to use the "Full Field" test.
 
1 - 5 of 5 Posts
Top