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Onan 30EK VR21 resistor R2 burnt


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  #1  
Old 11-23-2008, 03:05:29 AM
alexinvancouver alexinvancouver is offline
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Default Onan 30EK VR21 resistor R2 burnt

Hi every one,
I'm new here.
I got this Onan 30 EK that came with the property.
Engine starts and runs but generator doesn't work.
After removing VR I found out that resistor R2 burnt
I want to replace it but since it's burnt so badly
You wouldn't see what color stripes are.
So is there any one who knows how many Ohms it is?
Thanks in advance.
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  #2  
Old 11-23-2008, 10:38:34 AM
Jim Rankin Jim Rankin is offline
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Default Re: Onan 30EK VR21 resistor R2 burnt

It is listed as a 33 ohm 1/2 watt in the parts book I have for a larger set. Uses the same 1268 board though.
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Old 11-23-2008, 10:42:14 AM
Jim Rankin Jim Rankin is offline
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Default Re: Onan 30EK VR21 resistor R2 burnt

It's certainly possible there are other things wrong with the generator other than that one resister.

You need to measure residual voltage output, check the exciter breaker, etc.
Does it have brushes or is it brushless?
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Old 11-23-2008, 03:49:31 PM
alexinvancouver alexinvancouver is offline
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Default Re: Onan 30EK VR21 resistor R2 burnt

thank You Jim for replying.
i'm going to do some tests before replacing that board for sure.
I was told first to check resistance between F1 and F2
and yes, it has brushes.
I'm not sure how to measure residual voltage output or where the exiter breaker is, I didn't see it there.
Or You mean exciter switch?
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Old 11-23-2008, 10:54:53 PM
Jim Rankin Jim Rankin is offline
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Default Re: Onan 30EK VR21 resistor R2 burnt

Some level of AC output should be measurable from a running set, even if the exciter and regulator are totally inoperative. If not, the generator cannot start building up voltage. Measure between each line and neutral and line to line on the running set. Make sure to check that any output breaker isn't the problem by checking ahead of it as well as on the output. Some sets have an output breaker, some don't. There should be an exciter breaker on the panel of most (all?) sets with the VR21 regulator boards. It can be turned off to remove the excitation from the field or trips if excitation current is too high.

A small AC voltage which is symetrical from line to line and correct ratio of line to neutral vs line to line is a good sign that the stator is likely ok. Say you find that line-N is 4 volts (both lines) and L-L is 8 volts on a 120/240 set. That would be good. Finding L-N of 0 and 4 would be a bad sign probably. You can also measure resistance through the stator circuits and check for shorts to ground. A megohmeter is a tool especially made to check the insulation resistance for evidence of failure. You would want to isolate the exciter and regulator connections from any stator circuits before using a megohmeter.

The F+ to F- measurement is resistance through the field including the brushes and sliprings. High resistance across the field could be from stuck brushes, dirty sliprings or damaged field winding. While you're checking the field resistance also check the resistance between the field connection and the shaft of the rotor. That should be infinite. If not, check it again with the Field leads isolated from any terminal block etc so there's no chance of it being grounded through the exciter or regulator.

If you have a good stator readings with low residual voltage and also a good field resistance reading with no shorts to the frame, you probably should flash the field as a next step. You can apply DC voltage to the field from a battery either with the set stopped or running. If it's running apply the DC only for an instant and see if the AC output builds up or drops back to residual voltage levels as before. If it builds up while flashing but won't stay up, then go back to the regulator and exciter and troubleshoot. If it won't build up, there's a problem with the field or stator.

BE CAREFUL!
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Old 11-24-2008, 10:49:47 AM
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Billy J Shafer Billy J Shafer is offline
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Default Re: Onan 30EK VR21 resistor R2 burnt

Regulator failure was a common problem. They would get hotspots and fail. Not a bad unit just the way it is after hours of use. This maybe your only problem,but I would go through the checkout as Jim told you.
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Old 11-24-2008, 06:05:22 PM
alexinvancouver alexinvancouver is offline
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Default Re: Onan 30EK VR21 resistor R2 burnt

Thanks a lot guys for getting back to me.
I'm going to run those tests,
the only problem I'm facing is that property is 5 hours away
and there's a small village with no stores with
electronic components
so I got to do lots of running back and forth
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