generator repair?

Question

My generator has needed to be "demagnatized" twice in the last several years. While inexpensive, it is inconvenient to take to the repair place. Is this a service I can perform, and how would I go about learning how to do that?

The problem was the engine would run but we got not electricity from the outlets.

Answer 1

Sounds like the rotor had to be remagnetized, not demagnetized... If left for extended periods without use, sometimes the residual magnetism of the rotor can weaken. If this happens the engine will run but the output coils will not produce any voltage.

If this is the case you can sometimes restore it to operating condition quite easily. You need to "flash the field" to restore residual magnetism.

Shut off the engine and remove any cords from the generator. Plug in a cord with bare wires on the other end to one of the 120VAC outlets. Connect one end of the cord to a car battery. Very quickly touch the other wire to the other battery terminal. Do not leave it there longer than to create a few sparks or you may destroy the windings. If this doesn't work there is another technique which is a bit more tricky and potentially dangerous if not done properly.

I've seen a small tool for doing this on eBay. I'll try to find a link later...

Start the engine and apply a small load to see if it is working again. You should run the generator every month or so with a load attached to ensure everything is working as it should. No point having a generator if it won't work when needed.

Have a look through my generator page for other safety and operating ideas.

http://members.rennlist.org/warren/generator.html

There are some other scary techniques for doing this as well...
Do a web search for restore residual magnetism

Answer 2

What they are most likely doing is re-magnetize. The generator relies on a small amount of magnetism to remain in the iron called residual magnetism. A current is produced when a magnet passes a coil. Once the process is started the dc coils have power to become an electro magnet and produce the main power.

Sometimes this residual magnetism is lost but very rarely and there must be something else wrong for this to happen unless you are dropping the thing. Most likely the people you are taking it to don't know what else to do,so they simply get it going again.

Generators vary in design (brush or brushless etc) but basically all the people are doing is applying a battery to the dc coils. This can be done with the engine stopped using a good battery such as a car battery. Be aware there will be a spark when the connection is made and broken so be sure these sparks cannot ignite the hydrogen gas produced by car batteries. Also the coil will produce a back emf much higher than the battery voltage when the connection is broken so avoid direct contact or you may get shocked slightly. the voltage will make the coils into a electro magnet, hopefully leaving a residual in the iron afterwards

I have never heard of connecting the battery to the ac winding to do this as in the previous answer plaese let me know if this works without damaging anything

Answer 3

Pour a small amount of gasoline into a spray bottle such as a used shower spray bottle (be sure to clean all of the contents from the bottle first). Remove spark plug, spray three or four good sprays of gas into the spark plug hole and replace plug quickly. Pull starter rope, It should start for a few seconds until the gas is burnt up. If it does start and does not continue to run. You will have to remove fuel line going to carburetor and let gas drain into container. If this is old gas would discard. Now remove carb. clean and replace parts it needed. Reassemble, squirt a little gas in spark plug hole as before, pull starter cord and it should start and run...

Answer 4

Sounds to me like someone is blowing smoke up your a$$. I've never heard of such a thing!