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140 Electrical issue


nepoweshiekfarmalls
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I am trying to breathe life back into this tractor I purchased last month on auction. My parts book only shows the early 140 (look like a 560) and mine is a late model.  I believe that it is 12 volt negative ground because the hot wire to the coil is on the + terminal and the - side of the coil runs to the post on the side of the distributor.   However, a previous owner ran a second wire from the + post of the coil through what appears to be a diode or resistor and attached it to the bolt that mounts the coil to the distributor housing.  Why would he do that?  Why run a hot wire to ground?  If he was trying to reduce the voltage to 6 volt for the points  you would either A: use a resistor in line before the coil  or B: use an internally resisted coil.  

I am experiencing intermittent fire to the plugs and cannot get the engine to fire. Upon inspection,  discovered that goofy wire and removed it.  Still no success.  Any suggestions? Thoughts?

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Is it silver? If it is, put the "goofy" thing back on, but put it on the - side of the coil.  The PO hooked it to the wrong side of the coil.  It is a condenser, and it has to be on there.  

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It has a condenser inside the distributor already. Why would it need another one?  This was a homemade wire with crimp on ends and the diode/ resistor was soldered to the wire and poorly covered with black tape.

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I can think of a few reasons why someone might try something like this - mostly from misunderstanding how it works.   1) its a 'clipping diode", allowing the reverse voltage pulse from the coil to travel to ground.  Trying to replace condensor, but incorrect  2) its a resistor, but installed wrong.  3) trying to get the tractor to shut off (wiring incorrect, alternator keeps it running).   You mght post a picture of the offending item so we can identify it??

I'd strip it off and get back to original.   Start there, check that your coil is a 12V coil, check for spark at the points, and see what you got.  I've seen gas engines with spark at the points (opened with a screwdriver) that would not run, because the distributor shaft bushing was so worn that when it turned the points didn't open right.  Often overlooked.

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1 hour ago, Jeff-C-IL said:

I can think of a few reasons why someone might try something like this - mostly from misunderstanding how it works.   1) its a 'clipping diode", allowing the reverse voltage pulse from the coil to travel to ground.  Trying to replace condensor, but incorrect  2) its a resistor, but installed wrong.  3) trying to get the tractor to shut off (wiring incorrect, alternator keeps it running).   You mght post a picture of the offending item so we can identify it??

I'd strip it off and get back to original.   Start there, check that your coil is a 12V coil, check for spark at the points, and see what you got.  I've seen gas engines with spark at the points (opened with a screwdriver) that would not run, because the distributor shaft bushing was so worn that when it turned the points didn't open right.  Often overlooked.

I should have posted a picture of it. Will do it tonight.  Looks like a little blue bead with tiny wires sticking out of each end.  Thank you!

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I should have included this information in my original post.   I hope this helps to make sense of the situation. I have included a photograph of the unusual wire assembly.  The second photo shows where it was attached before I removed it. (From the + side of the coil to the clamp assembly that secures the coil to the distributor housing.)  

I do not have a parts book for this late 140, but it appears that it came as a 12 volt.  I have a photo of the tag on the generator.  It is also wired as a 12 volt at the coil.  The current coil does not appear to be the original.  How can I test it to be sure it is 12 volt?  How can I test it to determine whether it is internally regulated?

One final mystery.   This unit is attached to the A terminal on the generator.   What is it?  Purpose?

I have worked on and re wired many tractors over the years, but this one has me scratching my head.  I hate to just throw a bunch of parts at it.  I would prefer to understand what is going on here and learn from it.  Thanks!

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I see a fender mount radio in the first picture. The unit mounted to the generator is a suppressor that is someone’s attempt to cut down static on the radio. No clue about the other item. 

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9 minutes ago, striker782 said:

I see a fender mount radio in the first picture. The unit mounted to the generator is a suppressor that is someone’s attempt to cut down static on the radio. No clue about the other item. 

When I first connected the battery, the radio began to play music!  The lights all work too.  Just need to decipher this electrical system and hear the engine run! Thank you for the tip about the suppressor for the radio.

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3 minutes ago, snoshoe said:

Both are capacitors for radio noise suppression

Interesting!  The one attached to the + side of the coil was poorly taped up.  I was attempting to start the tractor in near darkness and it was sparking to the body of the distributor.   What is stealing my power to the points, I wondered.

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4 minutes ago, nepoweshiekfarmalls said:

Interesting!  The one attached to the + side of the coil was poorly taped up.  I was attempting to start the tractor in near darkness and it was sparking to the body of the distributor.   What is stealing my power to the points, I wondered.

Do you have multi meter with cap test function?

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1 hour ago, snoshoe said:

Both are capacitors for radio noise suppression

I have a manual for IH fender radio and it notates a capacitor in the installation  instructions for noise suppression. 

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3 minutes ago, Sledgehammer said:

I have a manual for IH fender radio and it notates a capacitor in the installation  instructions for noise suppression. 

Where do they recommend installing the capacitor?

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2 hours ago, nepoweshiekfarmalls said:

Where do they recommend installing the capacitor?

Talks about it on bottom right of this pic I already had  I could take a new pic later if needed.  Don’t have it right in front of me.

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220 uF capacitor, used for noise suppression.   Thats a fairly large Cap.   Capacitors can fail - in fact when you have a piece of electronics that suddenly "pops", smokes, and fails, its usually a cap shorting out internally.   As noted, you need the Cap Test feature on a meter, which is rare.    

I think you are on the right track, remove those extra capacitors and see if it makes the engine run better.   

It there is no resistor in the circuit, you should measure 12V on the + side of the coil to a frame ground, the - terminal will either be 12V or 0V depending on if the points are open or closed.  

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Update.  Tested with a meter.  Coil is definitely 12V.  Have 12V to distributor.   So, I  installed cap, rotor, points, condenser tonight.   Manually activating the points makes a strong spark now.  Installed my temporary fuel tank again. (The tank needs a good flushing before I can use it.)  Turned on the ignition and hit the starter.  The engine fired immediately and went right into a smooth idle. Runs great! I drove it down and parked it in the shed for winter.  Ran the carburetor dry and removed the temporary fuel system and battery for winter.  Will address the fuel system and a few detail items next spring.   

Do I need to put in a resistor in with a 12 volt coil?  Will 12V burn out the points/ condenser?  When I  convert a 6 volt system,  I step down the power to the 6V coil with a resistor to prevent damage.  Not sure with this 12V coil.

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