8N running well, now need help with ammeter.

soberley · Dec 24, 2005

To all, I am posting this call for help. I noticed the Ammeter on my 8N was not working...it was constantly spiked all the way on the positive side. I did some research and purchased a new after market one. I saw tons of posts on how all you have to do is split the existing wire and terminate on the positive and negative sides of the new Ammeter if it shows a negative charge then reverse them.. Sounds easy right? Well I bought the Ammeter and drove to the property to do a little work on the tractor and found out someone beat me to the punch on removing the wires from the back of the Ammeter. After many long hours of further research I think I have one side identified, but am confused on the other side. I believe on wire hooks up to the lower stud on the terminal block (same as the ignition switch), but no idea where the other needs to go. (perhaps the load stud on the genny?)
The tractor specs are as follows: a 1949 or 50 8N 6 volt System front mount distributor.

By the way thanks to all for the suggestions on how to get it running again... I actually had a day to go play with it and when I went out it started and ran for about 30 seconds then died....couldn't get it started again. Started working fom the carb backwards and found the after market fuel filter was plugged up really bad and not letting hardly any fuel in. I had another one with me and replaced it. now I can start it at 1/3 throttle with a little choke and it runs like a top.
Thanks to all in advance...

soberley · Dec 27, 2005

Found out the sequence of hookup for the Ammeter. you have a cable that runs from the battery neg. to a post on the starter solenoid. A wire runs from that to the lower stud on the resistor terminal block. that is the wire that must be cut and the Ammeter hooks in line to it. I have tested it and it seems to show when I have a good draw I.E. headlights on. Even at full throttle it does not show a positive charge. The battery was fairly freshly charged and that may make a diffence. Does anyone have any knowledge of this?

Soundguy · Dec 29, 2005

Ok.. if you have the ammeter installe dcorrectly.. but don't see a positive charge.. look for a few things. First.. when you have a load.. like lamps on.. or ignition on.. does the ammeter deflect negative ( discharge? )

If it does.. try to polarize the vr/genny.. A-circuit systems polarize by momentarilly jumpering arm and bat terminals with the tractor not running.

If you suspect the vr is bad, after the polerization.. jumper the field terminal on the genny to ground while it is running.. that should make max charge..you are bypassing the bias resistor and vibrating field contact... if you don't see charge, then jumper arm to bat to bypass cutout relay in vr.. if that don't do it.. genny needs attention.

engine off, remove belt, jumper arm and bat, ground field.. genny should turn like a motor.. if it does.. generally.. it should charge.. if it doesn't.. may be proud mica.. bad comutator.. bad field coils, or worn brushes.

Soundguy

soberley · Dec 29, 2005

I believe I have the Ammeter in correctly. It is showing a neg Charge when I use the headlights, But no possitive charge.

When I polarize the system should the ignition be off or on and the tractor not running?

Also I removed the battery and charged it and reinstalled it with a positive ground would this then require the re-polarization?

Thanks for the help!

Soundguy · Dec 29, 2005

( It is showing a neg Charge when I use the headlights, But no possitive charge.
)

It's showing a discharge.. ok.. that means you probably have the net charge/discharge wireing and the ammeter in correctly.

( When I polarize the system should the ignition be off or on and the tractor not running?
)

Position of the ignition switch will have no bearing whatsoever on polarizing the genny.. for all intents and purposes, the charge system and ignition system as seperate circuit branches, only sharing a common power source. Engine should NOT be running...

( Also I removed the battery and charged it and reinstalled it with a positive ground would this then require the re-polarization?
)

Any time you disassemble the genny, change the vr, or change the battery polarity, you should re-polarize. A unit that has sat for a very long time may need to be repolarized as well.

Soundguy

soberley · Jan 4, 2006

looks as though the polarizing worked! it now puts out about 20 or so amps at just over 7 volts. I hooked up all my lights and bypassed the ignition key switch to do so as I have heard it may not handle the draw. Thank you for all your help. I have just recieved the F-04 book for all the repairs yesterday and it will help a lot.
Again thanks for the advice!

Soundguy · Jan 4, 2006

Do keep an eye on the gauge.. it should only charge at 20a for a few moments/minutes after starting.. after that it should settle back down to 0-5 amps charge. If it stays high.. you may have the field still grounded.. either by a jumper wire.. etc,, or other..

Soundguy