Golden jubilee smoking electrics

jube newbe · Jun 15, 2009

Jubilee Newbie here,

Just bought it with loader and Sherman backhoe. had been sitting a year or so but ran when parked.

Ok so heres my problem, worked though the gas lines, tank, carb and the firing chamber is getting fuel, but no spark. I traced it back to the coil and replaced it. ( its been upgraded to 12 volt)

Went to the coil shop and was given a 6volt and told it would work fine . Got it home installed it and get smoke coming from What I gues is some kind of resistor (it's located to the right of the batery tray next to spark plug one, I unhooked it and ran it to negative but still smoke.

Whats up do I need a 12volt coil, new resistor thingy?
Will post sdome pic if anones intereted

Thanks in advance

Willl · Jun 15, 2009

jube newbe said:
was given a 6volt and told it would work fine .

They lied.

jube newbe said:
do I need a 12volt coil, new resistor thingy

Yup.

Willl · Jun 16, 2009

Another hint; coils with built in ballast vs coils without. (ballast would be the thingy I believe you burnt up)

Using a coil without a built in ballast on a unit that requires one will get you 3 blocks down the road and 1 block back. Leaving you 2 blocks short.

jinman · Jun 16, 2009

Even when sized correctly, ballast resistors often get very hot. The best way to fix the problem is to go to a 12 volt coil with built-in ballast since the rest of the system is 12 volts.

Do you know what a ballast resistor does? Many folks don't know, so don't feel bad. When your points are closed, you essentially have a dead short to ground from the 12 volt supply thru the coil and points to ground. The current can overheat the points and actually weld them together. It can also burn out the fine wires inside the coil. Adding an external resistor provides a voltage drop and current limiting when the points are closed. This is especially important when you turn on the ignition but don't have the engine running because your points may be closed and pulling maximum current continuously.

jube newbe · Jun 16, 2009

Thanks for the responses guys.

I kinda fugured it was some kind of resistor, looking at a 6 volt wiring diagram. It may have been shot already the previous was running a 12v coil.

This system will now be running negative earth right? So I'll put (+) on the coil to wire coming from starter/ resistor?

Cheers again

Willl · Jun 16, 2009

Ballast resistors do nothing more than supply the coil with a dropped down voltage of 9 volts during 'run mode'.

During 'crank mode' it by passes this resistor and supplies the coil with the full 12+ volts.

jinman · Jun 17, 2009

Willl said:
Ballast resistors do nothing more than supply the coil with a dropped down voltage of 9 volts during 'run mode'.

During 'crank mode' it by passes this resistor and supplies the coil with the full 12+ volts.

Okay Willl, I'll bite. What is it that tells the ballast resistor to be in the circuit or not? All I have ever seen are in series with the coil. When the points are open, there is no current flow after the condenser charges and the full 12 volts will be felt at the coil side of the points. As soon as the points close, the ballast resistor is in series with the coil to ground and drops voltage while limiting current. How could a series resistor possibly know the difference between "run mode" and "crank mode"? Maybe your tractors have been wired differently from mine.

jimmysisson · Jun 18, 2009

What I remember (long ago) was a lead from the start terminal of the ign switch direct to the coil primary. Another went from the run terminal of the switch to the resistor, then on to the same terminal of the coil. YMMV
Jim

jinman · Jun 18, 2009

jimmysisson said:
What I remember (long ago) was a lead from the start terminal of the ign switch direct to the coil primary. Another went from the run terminal of the switch to the resistor, then on to the same terminal of the coil. YMMV
Jim

Jim, that sounds prossible for an external ballast resistor, but a 12 vdc coil with a built-in ballast resistor only has one low voltage input lead and one output lead. The ballast resistor is inside the coil. Even if you wanted to, you could not wire in a parallel circuit that bypasses the resistor and goes to the coil's primary. Isn't that right?

Here is a link to some wiring diagrams showing before and after conversion with the addition of ballast resistors. All of them show a series resistor with no "start/run" bypass.

6 to 12 volt conversions