Brushless generator not producing any power

Somewhat tangentially to my other construction videos, I needed to diagnose and repair my brushless generator this week. Here is how that was done.

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Brushless alternators use a capacitor to introduce a charge into the windings. This gets them excited so the alternator will produce electricity. When my engine RPM surged, it surged the alternator and the capacitor blew to protect all the electronics downstream…
If the alternator is working, it produces a ~5 volt difference (plus or minus a volt or 2) across the capacitor. So, I just had to check the AC Voltage with my multimeter. It turned out the voltage was OK.

By process of elimination, I decided to order a new capacitor.
My original was covered with a layer of rust, so I couldn’t read the specifics. I checked the internet to find the right one for my generator, a 40µF, 370VAC generator capacitor. The genuine PorterCable part costs 60$. Now that I knew the specific properties, I was able to search based on that and found a Genteq knockoff that only cost 16$ with delivery. It claimed to be just as long lasting (60,000 hours), and like the much more expensive OEM product, it is also “self-extinguishing” so I won’t die in a terrifying fireball if it fails.

Its physical dimensions are a little different, but it fit. And more importantly, my generator works again.
Now my generator can do its job and give me electricity on my jobsite.