8N not charging

[Dan]

Working on my friends 6v positive ground1950 8N he just got and I. Noticed it wasn't charging. Did a quick polarization by shorting the BAT and ARM terminal on the voltage regulator with key off - no help. Shorted the BAT and ARM on the VR when running, no help. Shorted FLD on generator while running, no help. Appears that the VR as well as the generator are bad(?)

Unhooked everything from the generator and applied positive from battery to FLD and Negative from battery to ARM lug, did not motor. I had a fresh rebuilt generator on the shelf and when I try to motor the generator it jerks a tad when I apply the jumpers but won't spin, even with help.

Can someone sanity check my process and let me know if I am testing wrong?

 

[JMOR]

sounds ok, but try 'motoring' w/o connecting field

 

[Dan]

sounds ok, but try 'motoring' w/o connecting field

So, ground at the generator frame?

 

[JMOR]

So, ground at the generator frame?

yes, positive ground to gen frame

 

[Dan]

Update - retested the generators using Jmor's info and they both motored. Turned my attention back to the VR. Took the cover off and pressed the ARM contact point in and with a ground to the FLD on the generator the voltage came up on the battery and the ammeter showed +8 or so.

I assume that both the original and my back stock VR are bad(?) but not sure why I had to ground the FLD to get it to charge when I already forced the ARM contact.

 

[JMOR]

Update - retested the generators using Jmor's info and they both motored. Turned my attention back to the VR. Took the cover off and pressed the ARM contact point in and with a ground to the FLD on the generator the voltage came up on the battery and the ammeter showed +8 or so.

I assume that both the original and my back stock VR are bad(?) but not sure why I had to ground the FLD to get it to charge when I already forced the ARM contact.

Probably corroded field contacts.. Lightly file or sand and clean so that they can supply the ground to field. Field is supplied power from inside gen and receives gnd via VR field contacts.

 

[Dan]

Another question, VRs are sold by either front or side mount distributors. I "assume" the difference is between 3 or 2 brush generators and the type of distributor doesn't really matter - correct? This is a front mount tractor but has a later style 2 brush generator.

 

[JMOR]

Another question, VRs are sold by either front or side mount distributors. I "assume" the difference is between 3 or 2 brush generators and the type of distributor doesn't really matter - correct? This is a front mount tractor but has a later style 2 brush generator.

A 3 brush that has not been converted uses a cut out vs a regulator and which regulator depends on whether it is an early 11 1/2 amp or later 20 amp unit.

 

[Dan]

I saw a lightly stamped 8N part number on the generator when I was doing the motoring test. Any idea of early vs. later part numbers so I can ensure that I get the right one?

 

[JMOR]

I believe you will find that lower output gens will have a barrel dia of 4 1/2 " and higher output will be 4.8" dia... Earliest 9N & 2N gens had even smaller barrels.

https://imgur.com/4Alm2Cl

 

[Dan]

I believe you will find that lower output gens will have a barrel dia of 4 1/2 " and higher output will be 4.8" dia... Earliest 9N & 2N gens had even smaller barrels.

https://imgur.com/4Alm2Cl

It is an 8N1000B, your pic shows it with a front mount distributor so I guess I need to get the lower output VR. Thanks for the help!

 

[deanostoybox]

From:

Tractor Identification and Model History - Ford Fordson Collectors Association

By: John Smith of Old Ford Tractors

fordtractorcollectors.com

"At serial 137685 the generator changed to the larger capacity 8N10000-B generator. "
So not lower output regulator.
What happens to the regulators, even brand new ones that have been sitting on a shelf for a long time, is corrosion.
The contacts corrode, easily cleaned, the rivets rust and even the cadmium "anti-corrosion" coating can corrode.
If you can find where conductivity is lost and restore it you can make it work.