# Generator Questions



## RKDOC (Jun 20, 2006)

A man brought me a Dayton Generator. Model 4ZZ18 serial # 112999N 232837. He said it just quit producing power. The engine runs great and at proper speed (3600rpm). I have worked on the engines of generators before, but this is the first on the electrical side of the generator. I purchased a manual that covered Dayton generator but it does not cover this particular model. I also have the Briggs Generator service guide.

I have tested the rotor and it tests good. I have tested the circuit breakers and they test good. I have checked for loose or broken wires, none found. I checked the brushes, they are good. I would like to test the rectifier, however my service manuals show how to test a 3 terminal rectifier but mine is a 4 terminal type. Does anyone know how to test a 4 terminal rectifer?

In my briggs manual it talks about testing the stator. To do so it tells me to remove the red and the blue wires from the rectifier and test for continuity. Problem is there are 2 blue wires, how do I know which blue wire to remove and check? It talks about Checking the "excitation" wires to the stator. How do I know which wires are the "excitation" wires to the stator? Is there any other things I should be checking? Or ideas of what would cause the generator to just quit?

I am sorry for the rambling of this post, but I am trying to figure out the electrcal part of the generator. Thanks for all your help and the help many of you have given in the past, it is greatly appreciated.


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## newz7151 (Oct 15, 2006)

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## RKDOC (Jun 20, 2006)

newz7151, I did see your post about Graingers. They cannot get me a service manual. This generator is older and many parts are not available through Graingers. I am hoping to be able to pinpoint what is wrong then get the parts from an electrical outlet somwhere.

Thanks for the reply.


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## Propbuster48060 (Sep 29, 2007)

I don't know if you have gotten an answer yet , but I may be able to help. The 4 terminal rectifier (Full wave Bridge) is 4 diodes connected in a anode to anode / cathode to cathode configuration. you should be able to pull it out of the circuit (mark all wires first) and use an ohm meter to check it out. Do you have an ohm meter? A diode only really conducts in 1 direction so put the ohm meter on X100 and looking at the bridge rectifier 2 of the pronges should be labled AC, and the other 2 should have a + & -. Place the black lead on 1 of the AC prongs, and the red lead on the other, you will may get a reading, if you don't reverse the leads. If you still don't get a reading the bridge is open. If you get a reading 1 way but not the other, that 1/2 of the bridge is okay, now test the + & - prongs the same way. Some generators after sitting for as while will lose the residual magnetic field in the rotor, it may be reastablished by taking a standard 9 vdc radio battery and observing polarity jumping power to the brushes. A wire can be attached to the brush leads again observing polarity and momentarily attaching the battery to the leads this will induce/ magnetize the winding and it may start to produce power again. If your unsure of what I'm talking about you better take it to a qualified repairman


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