Onan Emerald 3 6.5 NHE Gen set

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Deano2002

Well-known member
Joined
Apr 21, 2013
Posts
897
Location
Morris, IL.
Hi all, I just put may generator back in the motorhome after a bearing replacement on the gen end, the generator fired right up and engine runs good like it did, hasn't been started in nearly a year. Before it was reassembled I cleaned the slip rings with 220 grit paper and the scotch bright pad, brushes looked good so I left as is. I went inside the coach and noticed the 120v fridge light was flickering and the transfer switch was rattling. I checked voltage across the brushes and had 70 volts if that's a valid test. I noticed that the voltage regulator was very hot almost not able to touch. Last year I checked voltage in the coach and it was at 149 volts so defiantly there was an issue. Now the service manual says to find the number 7 pin on the voltage reg and test that to ground with a multimeter, should be 12 volts and across the brushes 10-11 volts, today there is less than a volt at the regulator and nothing at the brushes. I assume these measurements are to be taken with the generator not running correct?
 

Matt_C

Well-known member
Joined
Mar 4, 2019
Posts
479
Location
SE - Mich
Deano,
Reading the manual was a good way to start.
Most of the trouble shooting measurements are taken with the machine running, the manual should say so. I can only guess, but it would seem to me that the regulator board is in trouble.
Matt
 

Deano2002

Well-known member
Joined
Apr 21, 2013
Posts
897
Location
Morris, IL.
manual says set meter at the lowest ohm setting for shorted rotor test, probe the two slip rings, should measure no less than 10.6 ohms @ 72 degrees, mine is measuring around 19+ at 92 degrees, not sure that being that high is good or its just the temperature. Checking for grounded rotor is setting meter at highest ohms setting than test from one slip ring to rotor shaft, then the other slip ring to shaft, ohm meter doesn't move. Anything less than 1 mega ohm means rotor is grounded, my meter at the highest setting doesn't move. Is that good or bad?
 

Deano2002

Well-known member
Joined
Apr 21, 2013
Posts
897
Location
Morris, IL.
Deano,
Reading the manual was a good way to start.
Most of the trouble shooting measurements are taken with the machine running, the manual should say so. I can only guess, but it would seem to me that the regulator board is in trouble.
Matt
Manual has many test while not running, the rotor has a few as well as the stator and voltage regulator, should have done this when it was on the bench just to have had peace of mind that these two expensive components are functioning as should be. I have half a mind to pull it again but, waiting to hear from a service center if they will even want to answer my questions, usually they don't want to, they want the service. I'm not the guy to bring it in, I usually can figure things out but, takes way too long
 

Deano2002

Well-known member
Joined
Apr 21, 2013
Posts
897
Location
Morris, IL.
Deano,
Reading the manual was a good way to start.
Most of the trouble shooting measurements are taken with the machine running, the manual should say so. I can only guess, but it would seem to me that the regulator board is in trouble.
Matt
manual didn't say while running, however another test while running shows across the brushes should be around 60 volts, I was nearly 70
 
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