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Need electrical diagram/testing procedure Tecumseh 4HP model OVRM120

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WilsonJackForum
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2016/07/01 09:50:57 (permalink)
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Need electrical diagram/testing procedure Tecumseh 4HP model OVRM120

Spec is: 22065H,  EN-STPXS.1951AA
It is a 4HP vertical engine and need electrical diagram to troubleshot. It is very unusual for me since it has something like a normal ignition coil but attached to this coil is another single coil heavier copper wound with one end to ground and the other to a small capacitor that goes out with a green wire under the flywheel.
Any assistance to locate a diagram or a test procedure to determine if the coils is bad is appreciated.
Ignition coil secondary reads 2,300 ohms and primary in  the range of 150 ohms.
I can post a picture of the coil if this would help.
 
Thanks, Wilson
Valentin31000@cs.com
 
post edited by WilsonJackForum - 2016/07/07 08:34:54

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    Mikel1
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    Re: Need electrical diagram/testing procedure Tecumseh 4H model OVRM120 2016/07/01 14:13:59 (permalink)
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    Looking up your model, only shows the solid state ignition. I take it your not getting a spark?
    Feel free to add pictures if you'd like.
    WilsonJackForum
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    Re: Need electrical diagram/testing procedure Tecumseh 4H model OVRM120 2016/07/01 17:35:08 (permalink)
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    Mikel1
    Looking up your model, only shows the solid state ignition. I take it your not getting a spark?
    Feel free to add pictures if you'd like.



    I attached 2 pictures and my best guess is that the red coil attached with 2 screws is just to charge batteries that probably this lawnmower originally had. The lawnmower was a Troybilt with a engine cover that said 7 HP but when I removed the cover I found a 4HP engine Tecumseh Model:nOVRM120. The engine has electric started but I do not know if need 120 Volts A/C or 12 Volts DC to start. Most of this has been cannibalized by someone. Now the engine will not start because it has NO spark. The plug for the electric starter is a "polarized", meaning that the electricity to the starter may need to be 12 Volts A/C but no sure. I need to find that out too, but I cannot find a repair manual or specs to the Tecumseh engine.
    I checked ohms at the coil and found this:
    1- Between high side to spark plug and ground= 2,800 ohms, so I assume this is the secondary winding.
    2- Between the connector tab as seeing in the attached picture and ground= 390 ohms, so I assume is the primary winding.
    3- Between  high side to spark plug and tab connector at the coil= 3, 200 ohms
    The last reading makes sense since the primary winding and secondary winding are in series with the measuring set up since 2,800 + 390 is approx. 3,200 ohms.
     
    Now I do not know if this engine utilizes "Points" to produce the spark and cannot get the flywheel of until I fabricate and adapter. If this engine has "points" I would assume the problem is bad contacts.
    Lastly, I saw the "additional" winding with heavier coil copper wire could be just a "charging" system since the coil has one end to ground and the other to a capacitor with a diode in parallel with the capacitor which makes it a 1/2 wave rectifier which is a "charging system".
    Anyone with some suggestions?
    Thanks, Wilson
    It seems that I could not understand how to upload the pictures from my computer or something it is not working right. I am a new member.
     
     
    WilsonJackForum
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    Re: Need electrical diagram/testing procedure Tecumseh 4H model OVRM120 2016/07/01 17:49:51 (permalink)
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    It seems the pictures uploaded now.
    Wilson
    Mikel1
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    Re: Need electrical diagram/testing procedure Tecumseh 4H model OVRM120 2016/07/01 22:48:50 (permalink)
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    Don't see any pictures.
    Both of these are for your model.
    Picture of alternator coil-
    https://www.partstree.com/parts/tecumseh/parts/36952/
     
    Starter 12V-
    https://www.jackssmallengines.com/jacks-parts-lookup/part/tecumseh/37753
     
    WilsonJackForum
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    Re: Need electrical diagram/testing procedure Tecumseh 4H model OVRM120 2016/07/07 08:33:45 (permalink)
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    Thanks, Does this engine uses points?  (to open/close the primary of the ignition coil or is just electronically fired?
    But if it is electronic, where is the physical circuit for the electronic components?
    Thanks, I just made the adapter to pull the flywheel and will check of there are points by the crankshaft, unless I hear before that the firing is without points.
    Mikel1
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    Re: Need electrical diagram/testing procedure Tecumseh 4H model OVRM120 2016/07/07 13:43:17 (permalink)
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    This is the only ignition coil I see for your model. Picture in link
    https://www.partstree.com/parts/tecumseh/parts/34443d/
     
    From Tecumseh service manual- OVRM= Overhead Valve Vertical Rotary Mower
    "Overhead valve 4 cycle Tecumseh engines use solid state capacitor discharge modules to provide high voltage to fire the spark plug. This is an all electronic ignition system with all the components located outside the flywheel. The solid state module is a complete unit that
    includes the laminations and spark plug wire."
    WilsonJackForum
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    Re: Need electrical diagram/testing procedure Tecumseh 4H model OVRM120 2016/07/18 08:13:15 (permalink)
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    Mike1: Is the ignition coil you suggested above the ONLY element that generates the spark when the flywheel/magnets rotate, or it the "alternator coil" also involved in generating the spark?
    Is the "Alternator Coil" utilized just to charge a auxiliary battery or Capacitor involved inf the CDI ignition system?
    Thanks, Wilson
    Mikel1
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    Re: Need electrical diagram/testing procedure Tecumseh 4H model OVRM120 2016/07/19 19:37:23 (permalink)
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    Yes, that is correct on the first part. Alternator coil is for charging battery in this application.
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