Guardian Ultra Source 15KW Low Output Voltage

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andrepie@aol.com
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My 15 KW Guardian Ultra Source portable generator only puts out approximately 34 VAC on the 120 outlet and 68 VAC across both hots on the 220 V outlet. The 12 volt plug only puts out approximately 3 volts. The frequency is around 60Hz.

Prior to a storm I connected the generator to my house to test it. I tried my air compressor which draws about 30 amps at start, and it would not run properly. I also tried to run my dryer which ran very slowly and the lights shined dim. Prior to the issue, the generator ran well, but it sat for about 6 months, while I was deployed with my wife only starting it to run the motor. While I was testing it, I plugged in an angle grinder, and it bumped a couple of times and then stopped working.

Thanks,
Andre'
Chris
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This sounds like residual voltage to me. Does the LED on the voltage regulator light up when it's running?
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andrepie@aol.com
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All three LEDs are are lit. Red (Regulator on), Yellow (Sensing input) and Green (Starter Excitation winding output). If I disconnect R1 from the diode, and measure the excitation voltage, it is 12 volts. If I reconnect diode 1, the measured voltage drops to 3.33 volts instead of approximately 9 volts. I tested the resistor and diode, and they both test good.
Chris
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It sounds like you have the diag manual for the unit, am I assuming correctly? If so, you should go through the procedure for field flashing the rotor (Test 4) and see if voltage goes up and is normal in every place you're supposed to have it. This will tell us a lot about the condition of the rotor and stator.
Generac tech for over 12 years. I'm here to help!
"The only source of knowledge is experience" -Albert Einstein
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andrepie@aol.com
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Thanks. I have the troubleshooting manual. I will do test 4 next.
andrepie@aol.com
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Well it works now, but I don't know why. After running all the tests, I reassembled everything, rechecked the output, and it worked.

Also, I don't know which model I have, I can't find any name plate that indicates the model. All I see is the motor name plate that says Engine ident no. OE622, Displacement 992.00 CC, Serial No. 7768050

Before it started working, I did Test 4 (Fixed Excitation Test/Rotor Amp Draw):
- ACV Wires 2 & 6 = 6.5 VAC
- ACV Wires 11S and 44S = .23 VAC
- Rotor Amp Draw = 0 Amps
Does that indicate a short or ground somewhere?

Test 8 (Diode and Resistor): both tested good
Test 11 (Excitation Wiring): Both wires good
Test 12 (Brush Leads): Good
Test 13 (Brushes and Slip Rings): Good
Test 14 (Rotor Assembly): 15.88 Ohms

I went ahead and tested the stator (Test 9)
- Power Wires 11 & 22 = .17 Ohms
- Power Wires 44 & 22 = .17 Ohms
- Sensing Wires 11S & 44S = .32 Ohms
- Excitation Wires 2 & 6 = .68 Ohms
- Battery Charge Wires 66A & 77A = .25 Ohms
- Battery Charge Wires 66 & 77 = .25
andrepie@aol.com
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Figured it out. The problem came back, and I noticed the light I had plugged in started flickering when I touched the wires in the control panel. It was a bad connection in the idle control sensing circuit.
Chris
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Sorry I missed your last response! Been trying to keep up as best I can.

I'm surprised to hear that since the engine wasn't idling down? Or was it?
Generac tech for over 12 years. I'm here to help!
"The only source of knowledge is experience" -Albert Einstein
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