Powermate series 54 4000 W generator puts out electircity for about 2 ro 3 minutes then no electricity. Starts and runs fine; puts out electricity for about 2 to 3 minutes then no electricity. let cool, restart , get power for a minute. voltage on field(brush terminals) goes to zero when output stops. repeatable. brushes look ok. If cool maybe get a minute or two longer. Capacitor and diodes checked OK ( when cool).

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Hello Tombr,
You should buy a can of "freeze spray" and while the unit is running, and the output is at zero, spray the diodes to cool them off 1 by 1. The 1 that you last sprayed when the power returns is most likely the problem part, and needs to be replaced. You could replace all 4 diodes at once to be sure the problem doesn't return. The caps could be at fault and you can spray them also, but they most likely won't cause the issue you are having!
Good Luck!
Rich Lilja
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