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Subject: Starting Circuit Question for the Experienced Guys

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Jerry    Posted 11-22-2020 at 10:04:50 [URL] [DELETE]        [Reply] [Email]  
  • Starting Circuit Question for the Experienced Guys
  • I have an 841 converted to 12v. It starts up usually as I release the starter button. I assume it is the surge of voltage from releasing the engaged starter. I watched a short video on You Tube, https://www.youtube.com/watch?v=PCs5gAZBbxU, that shows a diagram where an extra wire is run either to the output side of the resistor or to the plus side of coil to supply more power to coil during the cranking of the starter and shuts off when the key is released from the start position. I ran a wire according to the diagram and the tractor starts immediately but as soon as I release the starter button it dies. It looks like he is displaying an ignition switch with a start/release position.

    My question is, do you think this will work on a tractor and, if so, how should it be wired assuming a starter button and an on/off ignition switch?

    Bob in KS    Posted 11-22-2020 at 12:10:45 [URL] [DELETE]        [Reply] [Email]  
  • Re: Starting Circuit Question for the Experienced Guys
  • "I have an 841 converted to 12v. It starts up usually as I release the starter button."

    I suspect that you have too much resistance in the coil circuit. Many 12 volt conversions are done with a kit that comes with an external resistor for the coil. Many times this resistor is installed in addition to a direct 12 volt no resistor required coil, or the resistor in the kit is too high an ohm value.

    A quick check would be to put a jumper wire across the resistor. If it starts easier you know the resistance is the problem.

    Check the resistance across the + and - primary terminals of the coil. If the resistance is near 3 ohms you have a direct 12 volt coil and need to remove any extra resistors.

    If the coil is 1 1/2 ohms it is a 6 volt coil and needs an added 1 1/2 ohm resistor for 12 volt system If this is your case, check the resistance of the resistor and if it is significantly greater than 1 1/2 ohms, replace it.

    Your tractor on 6 volts did not have the bypass, it should not need it now. Something with your bypass is not wired correctly.

    I have an 8N with side mount distributor that had same problem as yours when I got it. It had a direct 12 volt coil plus the kit resistor that measured over 5 ohms. I removed the resistor and it now starts like it should.

    Jerry    Posted 11-22-2020 at 13:42:52 [URL] [DELETE]        [Reply] [Email]  
  • Re: Starting Circuit Question for the Experienced Guys
  • Thanks for the responses. My resistor measures 1.5 ohms. The primary coil measurement is appx 1.5, secondary is 9800. This is a 12V coil that specifies an external resistor. With points closed, I am getting 12V in to the resistor and 7V out. My assumption is that even with everything at the proper level for normal operation, the voltage drop during cranking could be overcome with the extra circuit.

    mhb@ufe    Posted 11-22-2020 at 11:57:13 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Starting Circuit Question for the Experienced Guys
  • You shouldn't need a bypass wire for that system. When you converted it to 12 volts did you install a 12 volt coil? If you have a 12 volt coil you don't need the resistor. The resistor is only used with a 6 volt coil. Many of the conversion kits come with a 12 volt coil and a resistor which doesn't make sense.


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