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Hank F.
Hank F., Technician
Category: Small Engine
Satisfied Customers: 14435
Experience:  Certified on Onan and Generac generators
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I have a dayton mod. 3w736c 4000w generator and blew a capacitor.

Customer Question

I have a dayton mod. 3w736c 4000w generator and blew a capacitor. Every thing else checks ok. I replaced capacitor but still will not generate, do i need to flash the field?
If I do, what voltage and main winding or cap. windings?
Submitted: 6 years ago.
Category: Small Engine
Expert:  Hank F. replied 6 years ago.


Yes, you may have to flash the field.

Here is the simplest way to do it.


1. Remove the spark plug wire.

2. Obtain an old extension cord that you can cut one end off, or an old power cord from an appliance (you will need the male end).

3. Note how on the receptacle, one slot is longer than the other. This longer slot is the negative slot. It is critical that you get it hooked up correctly.

4. Determine which wire of the cord will go to the negative slot.

5. Connect the negative wire to the negative terminal of a 12V battery.

6. Connect the positive wire to the positive terminal of the battery.

7. Plug the cord into the receptacle and pull the starter cord 6-8 times.

8. Immediately unplug the cord. DO NOT LEAVE THE CORD PLUGGED IN FOR MORE THAN 6 OR 8 SECONDS.

9. Disconnect the wires from the battery.

10. Reconnect the spark plug wire and see if the set is now producing electricity.


Hank F. and 3 other Small Engine Specialists are ready to help you
Customer: replied 6 years ago.

This did not work. The generator is 120/240 volts and this is only flashing haif the field. Do I need to use the 240 volt outlet and flash the entire field?

Expert:  Hank F. replied 6 years ago.

There is only 1 field. There is no way to only flash half of it.


There are only 4 things that will cause this set to not produce electricity:

1. Loss of residual magnetism. This is what flashing the field fixes. There is another way to flash the field, if you want to try it. Simply apply 12V across the terminals of the capacitor for 2-3 seconds.

2. Bad rectifier (diodes). Testing them is simple, but I would need you to get a picture of them so I can determine which type they are.

3. Open winding in the rotor (field winding). This can be tested with an ohmmeter.

4. Open winding in the stator.


To test the field winding, disconnect one lead coming off the rotor. Set your meter to ohms and place one lead against each rotor lead. What is the resistance?


To test the main windings, disconnect the 4 large leads that come out of the stator.

There will be 1 ground, 1 neutral and 2 hots.

Set your meter to ohms.

Test across the following wires:

Neutral to hot 1.

Neutral to hot 2.

Neutral to generator frame.

Hot 1 to hot 2.

Hot 1 to generator frame.


What are the resistances of all of these?


Expert:  Hank F. replied 6 years ago.

Were you able to do the tests yet?


Expert:  Hank F. replied 6 years ago.

I'm glad you got it going, but it should not have taken that long to flash the capacitor. 2 to 3 seconds should have been plenty of time.


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