35kw Get only putting 50 volts

[sfus2645]

Hi, I have a 35KW GET with a John Deere engine and a marathon generator. The pump was shut, I rebuilt it and work fine now, but it's only putting 50 to 55 volts.

 

[87cr250r]

That's usually the result of a failed voltage regulator, residual magnetism is generating the voltage. Put a load on it and it will drop to zero.

 

[sfus2645]

Any idea how to repair or replace the voltage regulator on this unit.?

 

[jamawieb]

The voltage regulator is on the back wall behind the gauges. Look in and its to the left. Its a marathon 350. You can buy an aftermarket on ebay fairly cheap.

 

[sfus2645]

I ordered a new voltage regulator and still have the same problem. Any other suggestions?

 

[Guyfang]

I would trace the Excitation from the VR to the Main gen.

 

[jamawieb]

Make sure your connections are tight on the vr. I just had a unit with a similar problem and after wiggling wires that connect to the vr it would produce correct voltage when i held them in the perfect position. Took the vr off and checked the connectors and one was about to fall off the wire. Fixed the issue after replacing the connector.

 

[Poccur]

Google flashing the field and constant excitation tests..if you are still stuck, PM me and I can help more...

 

[sfus2645]

Thank you,
I'm going to work on it, I just received a new voltage regulator

 

[Poccur]

So, how is it going? Still stuck?

 

[sfus2645]

I installed the new VR but it doesn't work either.
Maybe is something else.

 

[Poccur]

I installed the new VR but it doesn't work either.
Maybe is something else.

So assuming you have the new regulator on..and unit is turned off..

There is a test you can do which will prove to you that the generator is capable of making voltage and being stable. That will put your mind at rest that the issue is the regulator.

If you unhook F+ and F- from the regulator then carefully attach the wires you pull off to a 12 volt battery. F+ to positive, F- to negative...That removes the regulator from the circuit and pushes 12vdc down into the generator. Leave wires connected and restart engine...voltage should shoot up to around 220 VDC and be stable...Basically the battery is taking the place of the regulator and exciting the field in the generator to make voltage.
When I do this test I use wires with an inline fuse as the car battery I have for the 12volts has way too many amps for safety if the wires ground out by accident....really recommend you use fuse or circuit breaker on battery wires.
If that does not work, the problem is in the generator, if it does work you have now flashed the field at the same time as proving it functional.
Reconnect F+ and F- and set the voltage and frequency to 208V and 60Hz..

Just be super careful not to accidently short out the battery when attaching to generator wiring...just remember to push the 12 voltage into the gen, not into the regulator

Poccur

 

[sfus2645]

Thank you very much
I will try the test tomorrow.