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HoyBoy53

Regulator test

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I need to test the voltage regulator on my 1992 520H. I was told by a wheel horse mechanic that on these older Wheel Horse tractors, the regulator can go bad and charge too much power, eventually ruining the battery as well as other electrical components over time. I bought this tractor a month ago and it had a new battery in it. Per the mechanic that's a sign that something may be wrong with the regulator. Also the mechanic said, when the regulator malfunctions and over charges the system, several electrical components can be destroyed, one at a time if the problem is not corrected. No lights work on the tractor and the tach sits just under 4K at all RPMs. I just had to change the ignition module or "trigger". How do I test the power being sent through / out of the regulator?

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Use a multimeter set to the DC scale and put the red lead on the output side of the regulator and the black lead to ground. Make sure that the regulator is securely grounded. A bad ground can give you an over-voltage condition. At 3600 rpm you should be reading about 14.5 VDC. A regulator should always be tested with the battery connected.

 

If in doubt, just get a new regulator. They are inexpensive.

 

 

 

Edited by rmaynard
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With a multi-meter, on the output lug of the regulator measure the voltage while engine running from idle to WOT 11.8-13.6 volts should be a functioning range, anything less or more regulator should be replaced, you can find them on eBay and Amazon for $20 or less just not genuine Onan, Jeff.

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:WRS:            With any electrical problem the first step is to clean and tighten all electrical connections including grounds. As Bob said, if corrosion builds up between the regulator and ground overcharging will result. Simple maintenance will keep it going for decades.

29 minutes ago, HoyBoy53 said:

bought this tractor a month ago and it had a new battery in it. Per the mechanic that's a sign that something may be wrong with the regulator.

Or, could it be the battery was replaced because it was old?

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Used a multimeter on DCV to the battery with the original regulator still in the tractor. When running at about 1500 rpm the reading was 15.2 volts. Switched regulators to a spare from a 1988 and the same test showed 14.3. I think this regulator needs to be replaced. Ordered a replacement today.

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Biggest issue with any of these regulators is the chassis ground path - unless it's very clean and doesn't present any resistance it will cause the regulator to run wild since it cannot properly read the system voltage. You can test this by putting an ohm meter between the regulator case and negative battery terminal - it should read zero. Without a solid ground, I've seen several try to push the system up to over 17vdc, not good...

 

Sarge

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