USAF FL-1D No output power

[oldtruck51]

Picked up floodlight genset but it has no output power. I have flashed field and restarted, no change. When I leave field flashed with 12v and start unit I get 108-110v to outlet plugs. Reattach field wires to Voltage regulator and start, still no output power. Replaced voltage regulator, same problem. I pulled generator apart and had bridge rectifiers replaced. Put back together and exact same issue. I'm wondering has the rotor been damaged that it is unable to hold residual magnetism? Exciter and stator tested, no apparent problems. Has anyone else had this problem?
Any help would be appreciated.
Thanks.

 

[Guyfang]

You need to measure at F1 and F2 wires, for voltage when you start up the engine. The Main Gen needs Initial Excitation, before it can produce power. So check that first to see it it is in fact happening.

 

[oldtruck51]

Measured between F1 and F2 varies between 0 and 2vdc
When I remove F1 and F2 from voltage regulator and put 12vdc to them, I get 207vac between the other wires (Phase to Phase) on the voltage regulator, 102 vac to ground (phase to ground).

 

[Guyfang]

Sounds like the VR is not sending exciter voltage to the Main gen. Is there a schematic on the door of the light set?

 

[oldtruck51]

Here's the one from the manual. Without flashing the field I get 4.5 to 6vac at terminal 3 and 4 on the voltage regulator. When I flash F- and F+ I get 207vac at those same terminals. I've replaced the voltage regulator but get the same results.

 

[Guyfang]

Is 4.5 to 6vac That's inductive voltage. To flash the fields you need to see on those two wires DC voltage. That's F1 & F2 function. To give the initial excitation voltage. Un-hook the wires to terminals 3&4. Hook up the DMM to them, to measure DCV. Try and start the set. Do you get any DCV? Is the 5amp breaker good?

 

[oldtruck51]

Wanted to thank you for the info. After trouble shooting further I found the new AVR I bought had no output voltage, replaced fuse and still no output power. Not sure if it was bad when I got it or was just too complicated for this unit. I purchased an SE350 AVR off of amazon and installed it and low and behold I got power. Unit is working like a charm. Thanks again.