MEP-002A Sudden Hertz Drop

[ctucker3]

I was using my MEP-002A generator the other day, at 60 Hz, and the Hz meter dropped all the way to the left to 55 Hz and was audibly running slower. When I went over to check out what had happened, I could smell that something was burnt in the generator. I was running it in the 120/240 V mode, using the 120V convenience outlets, and was putting a load (a circular saw) on it every 10-20 minutes over the course of a couple of hours before the Hz drop occurred.

A little extra information. I can still start it up, but the Hz meter stays all the way to the left, even when attempting to raise the Hz with the adjustment knob.

Does anyone have any recommendations of troubleshooting steps to take to see what happened? Or does anyone have any idea of what could have happened?

[GMG]

Hz is directly proportional to engine speed. Have you checked the convenience outlet with a multi-meter to rule out a bad meter? If not, do so. There is a fuse on the convenience outlet that you should check as well. You didn’t say whether you can still use the convenience outlet.

[ctucker3]

Just checked it with a multi-meter, the convenience outlet is outputting 60 Hz, but only 2V. The Hz meter on the generator is still all the way to left though. The convenience outlet breaker is not tripped either.

Also, I opened up the electrical side panel, and can smell that the burning smell was something electrical in there. I can’t find any burnt areas from a shortage in there though.

Also, not sure if this detail matters, but, all the symptoms are the same when running on the 120V mode and the 120/240 mode.

So, it seems like the engine is good, and that it is something with the electrical components?

[GMG]

Voltage regulator issue, most likely from idling unit below 1800 rpm. These units must be run at 1800 rpm (=60Hz).

[ctucker3]

Hrmm, strange, I always run the generator at 60Hz from start up as you recommend on your site, so I do not think that would be the cause. Are there any other common causes of the voltage regulator panel breaking?

I think I found the issue. I opened up the control box and took a look at the voltage regulator on the left side and found that component C11, line 17 of the voltage regulator board was fried and had bubbled out the side of it. In Figure 6-4 of this manual,

https://media.greenmountaingenerators.com/wp-content/uploads/2012/10/02032832/MEP-002A-Intermediate-and-Depot-Level-Maintenance-Manual-TM-5-6115-584-34.pdf

you can see that in the DC voltage test, this component is part of the circuit that you test.

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