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Alternator dead short


richp

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I have a Simp. 7014s with Briggs 16hp that I put a new alternator on. This is the duel circuit type under fylwheel that has two wires that come out from behind flywheel housing. One wire is a/c for lights and other is dc for charging. When I touch the dc wire to hot side of solonoid it has a low voltage spark, or short (motor not running). Any ideas what is wrong? I am puzzled.
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Hi, Sounds like either the rectifier is shorted or the battery got installed backwards. If the battery got connected backwards there is a good chance the rectifier is shorted because of it, if it was connected for very long. If the alternator is brand new, there is a slim chance the rectifier got installed backwards or the diode got labeled wrong, though this would be very rare. To check the diode, WITH THE BATTERY DISCONNECTED, take an ohmmeter and check the resistance from the alternator DC lead to ground, then reverse the leads from the meter and recheck it. If the resistance is low one way and high the other way the diode is probably OK. Let us know what you find, and we can go from there. Good luck, Al Eden
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Thanks for the response Al. With ohmeter on the dc lead and ground it reads 0.00 for both ways. Where is the rectifier? All I have is the alternator ring and the two wires coming out. Is it internal to the Alt? Also, I am getting about 8 volts out of the ac wire at idle but nothing out of the dc wire.
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Rich, Does the tractor engine have a little bracket by the starter with a fuseholder like socket and a wire through the cap. If it does there is supposed to be a diode and not a fuse in there. The diode is replaceable and available from Briggs as a separate part. One end has like a flat head rivet crimped on and the has a little sleeve to crimp or solder the wire to. If it has this socket, a lot of people put a fuse in it and if they put too large of one in it, it burns up the stator. Al
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Your right Al. Here's what I did wrong. I noticed the new alt. had a white plug on the end and the old had the bracket and what I thought was a fuse holder. I looked real close at the Briggs repair manual and noticed the diode inline with plug end. I had cut off the white plug and soldered on the old wires eliminating the diode. Previous owner had gutted the diode holder and ran wire through the holder with a crimp on spade terminal. My guess is the old Alt. is still good. Well I learned something new. Thanks Al.
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