Old 1750W Generator - No Voltage


Old 05-15-16, 09:07 PM
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Old 1750W Generator - No Voltage

Hi. I got a generator from a garage sale for $15. Seemed like a good deal, even though it had problems. Engine runs great. Starts first pull (once I figured out where the choke was). Problem is, like I was told, it produces no electricity. The guy said he thought it was the brushes, so he replaced them, but he still couldn't get it to work, that's why he was selling it. I thought maybe, from what I was read on the internet, it needed to be "flashed". I tried the drill method, and it failed. Finally, I got it to sorta work, by unplugging the two wires on the brushes that go to the rectifier and starting the engine, then hooking the wires up to a car battery. The light I had plugged in finally lit up and the multimeter quickly went up to 268 volts (only supposed to a 120 volt generator). Once I remove the battery, though, the voltage goes back down to 3 volts (at the outlet), even after I plug the rectifier back in.

Engine is a 4HP Briggs and Stratton, horizontal shaft.
Alternator says "AG-Tronics" and it's 1750 watts. Model number is faded. All I know is it is very old and I can't find much about it.


The red wires go to the coils of wire on the side (there are two) (I think this is the stator?)
Two of the white wires go to the brushes and the the third goes to the power outlet.
The thinner wire wire connects the two coils of wire together. The resistance between each coil (Red/thin white) is 3.4 Ohms (ea coil) (although it kept changing, but that was the average ohms).

Checked the diode/rectifier with an ohm meter and got ∞ between both AC terminals. 500 ohms + to AC, 500 ohms - to other AC. ∞ + to -. The 500 ohms I got depended on polarity, if I switched the leads, it would be ∞. I'm not really sure what to do next. What could be wrong with it?
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Old 05-20-16, 06:08 AM
Join Date: May 2006
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Hi, No expert here, but I believe a generator with brushes uses a voltage regulator to send voltage to the brushes, just enough to produce 120v output.
When you sent 12v to the brushes and got output would seem to indicate that the rotor and stator are probably OK. I'm not sure if you could find a replacement regulator. There are places that rebuild regulators, but it's probably not worth the money for an old small unit. Maybe look through ebay and match something up?
Good luck, Steve
Old 05-22-16, 10:37 AM
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I can't find a voltage regulator anywhere on it. I thought all generators had one, too. Although, I found a shop that works on electric motors. They said it'd only cost $25 to look at it, so I'll take it there sometime and see what they say. If it's too much to fix, I'll probably use the engine on my go-kart, since I need a new engine for that anyway. Thanks for the help, though.

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