CM69502
 I have just purchased a Generac 25kw (I believe to be model 52120) 2.5L Ford motor which was sitting for a while and has a 067680 voltage regulator. The generator started right up and runs good, very low voltage and only sense light on. After measuring the 1-4 at 1TB the resistance was high. So the slip rings were clean, brushes looked good and holders cleaned, the unit now has 9 ohms. After running it, excitation light is on, but seem a little dim with no red light and output at the main breaker is 45VAC. I've read a lot of posts like this and verified voltage regulator switches and connections. Voltage out of field boost is 5VDC at TB1. If the lead is disconnected at TB1 field boost is 12.5. I've jumped battery voltage to terminal 4, which make all three lights come on bright on voltage regulator, but only 126VAC at the main output breaker and as soon as its removed the voltage drops to 45VAC again. I've done a lot of checks per the diagnostic manual I have, but I can't seem to find a diagnostic manual for this specific model. Any thoughts on the low voltage output? I figure the field boost kit may be a good idea from reading on this forum. Thank you so much!
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78buckshot
Welcome to the forum. Have you measured battery voltage while the unit is running? have you adjusted the voltage regulator while the jumper is connected?
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78buckshot
More to check, do you have a means of checking frequency while its running, the controller can be set up for different freq. and low speed exercise so if you can get a reading we can continue.
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CM69502
Thank you!  The battery voltage while running is 13.5V (brand new battery) battery charger is working also. I haven't touched any adjustments on the VR. I have set the exercise and noted the low speed. I'm not sure of the manual engine speed but its higher than exercise speed. The unit was tested and working before removal I was told. I do have a meter to check frequency and can do so afternoon. I appreciate your thoughts.
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78buckshot
If it's running at a higher speed than the low speed exercise then I would say it's good, the board can be set up for 50hz. or 60hz. So in manual run you should see 60hz and then try to adjust the voltage on the regulator to see if it responds to adjustment, we'll go from there. That model will run at 1800 RPM in high speed.
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Peddler
From what it sounds you are not getting anything out of the DPE winding.  Without a SN I can't research it but it could be an open or failed DPE breaker or an open thermal in the DPE winding.  The wire #6 & #2 come from the stator and bring unregulated AC voltage to power the voltage regulator.  The #2 wire changes to #162 after it passes through the CB2 DPE breaker which could be the problem,  Check for AC on #162 and # 6 at the voltage regulator while jumping 12 VDC to #4.  Report back. 
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CM69502
Thank you for the comments. I was able to check the Freq and its right at 60hz, RPM is at 1800RPM higher than exercise. While it was running, with green and yellow lights on VR, I manipulated the VR orange plug and the red light came on with 240V at the main breaker now. I shut it off and restarted and all the lights came on by their self. I've ordered a replacement orange plug and waiting for it arrive. I'll update once its replaced. Any ideas on a diagnostic manual for this model? Unfortunately the tag is damaged and I can't read the S/N. Is it located any where else? Thank you!
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78buckshot
If you want to take some pictures of the controls and cabinet and post them we might be able to recommend a manual.
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