Onan 4000 producing 145 AC Volts!

[California_Boon]

MY 1989 Fleetwood with the Onan 4000 (of that era) have worked flawlessly for over 600 hours. Sometime in the past couple trips the ancient power convertor started making odd noises. I checked ac voltage output while the generator was running with a dvm, and it was producing 145 volts.

Not sure why suddenly this would happen, but things do fall out of calibration or wear out. As I was dry camping in the desert, I adjusted the rpm's down to bring the output back to about 125 volts.

My fear is that the frequency may have correspondingly dropped from 60 Hz with this change.

When I returned home, I ordered a new power convertor to replace the old Magnatek from Progressive--and I've made an appt at the local Cummins (Onan) shop for calibration of the generator.

Just wondering if this is something anyone else has experienced? Do generators have voltage regulators that go out??

Thanks in advance.

[jolooote]

American equipment does not like 50 Hz.

[California_Boon]

Chris Bryant wrote:
Do yourself a favor and buy a Kill-a-watt meter and keep it plugged in- it reads both voltage and frequency.

I did Chris! Thanks for the suggestion. This tool validated my concern--in that turning down the governor to bring the voltage level down to 120 VAC, also reduced the frequency (Hz) from 60 to 50!

[California_Boon]

Update:
Had the unit tested/serviced at Onan, they discovered a faulty voltage regulator PC board (I suspected that would be the problem). The good news was they had it in stock (the genny is 25 years old)--the bad news was it cost $384! With some labor on top, drove home 90 minutes later $500 lighter in my wallet.

Upon arriving home, I spent another hour replacing the pathetic Magnatek power converter with a new Progressive Dynamics 4645 (that I had purchased a week previous in anticipation of getting the genny fixed). It was pretty straight forward, and was a slide-in replacement. I'm sure it will make a huge difference with battery charging alone.

The physical difference in electronics inside the old and the new was startling. The Magnatek looked a 7th grade electronic experiment...

Thanks again for your comments and suggestions.

[Chris_Bryant]

Do yourself a favor and buy a Kill-a-watt meter and keep it plugged in- it reads both voltage and frequency.

[California_Boon]

Thanks to all of you who have replied. You've provided some really good info as usual!

[MEXICOWANDERER]

Two clocks
One analog with second hand that sweeps without clicks
The othet a digital watch or clock battery powered.

Plug in analog clock run generator for 10-minutes.
Slow analog clock increase engine speed or verse visa.

Of course newer multimeters have Hz function which is faster.

ALWAYS keep governor linkage lubed. 40 weight motor oil works good. WD40 is useless.

[dougrainer]

Your model the engine RPM must be 1800. Lower and it will produce lower voltage, Higher and it will produce high voltage. You need a Frequency meter and need to have the GOVERNOR adjusted. There is NO speed screw on your model. There IS an idle screw, but that screw does NOT engage at all as long as the Carb is set up correctly. The idle screw just keeps the engine from slowing down and the usual voltage when the idle screw hits the carb stop, I believe is 90 volts. The NO load voltage on your model is 126 to 132 volts. At that range your Freq will be 60 htz. Doug

[j-d]

The flightsystems site has some interesting ONAN troubleshooting.

[ksg5000]

Your Onan 4000 Emerald Plus puts out voltage in direct proportion to the engine revolutions .. just need to adjust the speed screw - might also consider checking to insure that all the linkage is lubed and not stucked.

[time2roll]

Can't help with the generator but 145 volts demonstrates the utility of having a Progressive Industries EMS with voltage protection.

PD converter will be like a rocket compared to the MT.