Yes sir...A little background...I work for a company which is also a DoD Contractor and while I'm in Michigan, these US Army owned Generators are in Japan, so getting to the cause of problems has been difficult...None of the original crew remains on site, so background is less than reliable, but I am also told these worked correctly during day usage, for a couple of weeks...Then would immediately display the Under Voltage Fault light, upon start up...I too was puzzled with both of these having the same faults, while initially having and electrician perform basic troubleshooting steps, that I was directing over the phone...Only two common "pilot error" operator mistakes were revealed while discussing background,
1.) when I had him send photo's, I saw that the Neutral and A Phase Cables were mixed up on the Output Terminal Board (this could have made a real mess if hit with a big load!)...and
2.) He revealed that when attempting to "jump" due to start a low battery, they likely put cables in parallel, instead of series...thereby likely running 36-38 VDC through DC system...
Not successfully solving the problems over the phone (electrician was not very cooperative and may have been the one that mixed output cables too), I took the long trip (Japan) to visit these Generators personally (had other business at site), but only had a short time (1/2 Day) to troubleshoot, and very few tools at site...So having inspected and seeing/smelling no burnt cables from Stator to Reconnection Panel, then to TB2, when I tested the output values and noted the low VAC values, it was at the Output Terminal Board (where it matters most), while running in Battle Short, because the Circuit Interrupter wouldn't hold otherwise due to the Low Voltage Fault. (and see that I have the L-L and L-N values reversed in my original post)
As stated originally too, both of these units have been in a pretty wet/humid environment, for quite some time, and therefore display appreciable corrosion/electrolysis at terminations...Neither VAC Meter, or Frequency Meter (Hertz) work correctly, but I was able to measure at Hz AVR and verify correct RPM's from engine, and adjust same up and down, with Frequency Adjust Potentiometers, on both units...And incidental to your kind response, the Frequency Transducer in not mentioned in the Troubleshooting guide for either No or Low Voltage Output...so I didn't test it.
So I've recommended that the Contractor try to wash their hands of these, should never have accpted responsibility in the first place...And owning unit should send to Depot for re-set...but the "client" wants a ECOD/R...and being that I wasn't able to definitively isolate the problems (feeling rather defeated), I have to take the "shotgun approach" with parts...IE buy and replace all possible culprits...
I did run NSN's through Google the other day, and had just two vendors pop that allowed me to submit RFQ's...One seemed to specialize in AC Alternator parts, and the other with such as the Voltage Potential Transformer and AVR...And unfortunately one of these vendors (wbparts.com) just replied back with a strange response, asking "How soon do you need parts?" and "what is your target price?"...So I guess I should prepare to be disappointed more, to learn that there appears to be no reliable parts source for these?
Sigh...