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cncman08

ac 720 voltage regulator

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cncman08

Last weekend when I was mowing with the 720 I stop to fill with gas and noticed the battery bubbled over. I put the meter on the battery terminals after I restarted it and got 16.6 vdc at about half throttle. I have read the trouble shooting guide for the onan charging system, but before I start the trouble shooting I am wondering if these are the correct parts. Or if any one knows anything about them they look like something the previous owner did. The only place I can find them is onanparts. It also looks like they have been moved for easier access.

IMG_20150514_170114.jpg

IMG_20150514_170048.jpg

IMG_20150514_170114.jpg.bb028a3daed67201c152ad0689457841.jpg

IMG_20150514_170048.jpg.b546dbf0a0deed5ecf9ccbcc49282415.jpg

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midnightpumpkin

The rectifier and regulator MUST be well grounded. Are those nylon screws and nuts by any chance???

The modified mounting should be ok as long as they are grounded.

It may be a bad wire connection, the 16.6 volts sounds like either the regulator base is not ground or the red wire from the regulator is somehow not connected to the stator windings.

Here is a link to a troubleshooting guide by the late Al Eden.

http://www.simpletractors.com/club2/portal_External.asp?LinkID=150&LinkName=Troubleshooting%20Onan%20Charging%20Systems&CatID=30&CatTitle=Electrical&URL=http://www.simpletractors.com/club2/topic.asp?ARCHIVE=true&topic_id=514

Good luck

John U

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cncman08

They are nylon nuts. The one that is the rectifier has separated from the base. It still seems to be sealed and kind of just hangs there. And the other one has two wires that is the regulator? I did read in the trouble shooting guide that the regulator needed to be grounded and wondered why they had used nylon bolts. Are these original parts? Does it need to be grounded? Why would have the previous owner secured these with nylon screws.

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midnightpumpkin

You can epoxy the rectifier back to it's baseplate. Here is a picture of how I have been mounting the rectifer/regulator assemblies to make them accessable.

DSCN2885.JPG

Again, The regulator will not work if it's baseplate is not grounded.

DSCN2885.JPG.d0598e88ccd90b029d1397d5ccabd18a.JPG

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cncman08

Alright I checked the regulator as described in the trouble shooting guide. It had no deflection (leakage) when doing the red wire to base either way with the leads. The black wire had no deflection with the leads one way and readings between 3.0 and 12.0 the other. This is with a fluke 73 meter. I hooked the regulator back up and started. Now I am seeing readings between 16 and 20 vdc. I then grounded the base of the regulator to the ground terminal on the battery with jumper cables and recheck the voltage. Now it is reading 14.0 vdc. I will ground the regulator and hook up the multi meter when I mow next time so I can monitor the voltage until I am certain it's good. As of now it seems like I have it figured out. I cant believe that I am just catching this problem now. It has been like this for the last six years that I have owned the allis.

Thanks for the help midnightpumpkin

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midnightpumpkin

I would say that the regulator was making contact with the shroud in spite of the nylon screws. Over time it probably built up a film of oil and dirt enough that it lost contact.

John U

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cncman08

John I don't believe my regulator was ever grounded. It has plastic nuts between it and the shroud. The previous owner gave specific instructions to never let it and the rectifier to touch any metal. I guess he was wrong. The battery never seemed to hold a good charge a just figured it was a old battery. Hopefully since I just put a new battery in I can just refill what boiled out and it will be good. Where are the regulator and rectifier normally mounted? Under the flywheel?

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720nut

Mine are on the right side frame just under the flywheel, very difficult to get at. John like your idea both of mine are going to get that fix thanksdOdMan I've learned so much about these tractor in just a short time I've been a member thanks to all. goes to show you don't know it all

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midnightpumpkin
quote:Originally posted by cncman08

They are mounted to the shroud on the right side of the engine.

IMG_20150514_171458.jpg


id="quote">
id="quote">They were mounted in the 6 holes in the frame behind the steering link. The parts were mounted on the inside of the frame to make it easy to get to them (NOT).John U

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rmjens123

I am having charging problems also. I have a 9020 I bought 1 yr ago. Stator was unplugged. Ran test procedure and found bad rectifier. Replaced with one for Onan P motors. (regulator/ rectifier). Wired it as 2 black to ac, red to other ac 2 white to battery. Still not charging. Ran test procedure again and found stator was bad. Funding issue had me using all mowing season with it like this. I acquired a used stator. It outputs 16.4-17.2 volts a/c. Only Have1.6 volt d/c at battery output. Did I wire it wrong? Damage Reg/Rec using it this way? I added an extra ground to Reg/Rec. I too mounted mine on frame in front of motor. I am NEW here. Love this site. Trying to learn how yo use it. I am older and not up on these new fangled gadgets called computers. Hope posted this in the right place. Any help from such knowledgeable guys would be helpful more than words can say. I was a J D guy, but having discovered Powermax. There is no going back. MAX 9020

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