generator trouble

[jimkate]

We left our coach unattended for short time with the Onan 6500 propane generator running and one roof air conditioner running. When we returned, it was quiet. The generator was not running, and of course the roof air conditioner was also not running.

The generator restarted as normal, however the generator would not connect and produce any power. I checked the 30 amp breakers and the 10 amp fuse on the generator. I checked the breakers in the panel box at the back of the coach. I checked the fuses in the front run box. I couldn't find the problem, so we enjoyed a very hot outing this weekend.

Any ideas? First, why the generator stopped running in the first place? Second, why upon start up it won't connect and product any power?

[wa8yxm]

Onan generators self monitor and shut down if they are not putting out volts, or enough of them.

I assume you did check the breakers on the generator. Right, If not that's step one.

2: I would grab ye-old multimeter and start looking for voltage, Start with the GENERATOR terminals on the Auto Transfer switch, See if there is any output. No output, then move to the Generator output terminals, Same thing have re-check the breakers and after that.. Spend money, lots of it.

IF you find voltage in any of the above tests. post and we will continue.

[jimkate]

We fooled with it today. The Onan will start up and run, but will produce absolutely no electricity. Checked the brushes, current on the slip rings, wire connections, etc. Came to the conclusion that the voltage regulator is the culprit.

Onan in Canada don't have the voltage regulator, and want $583.00 to get one from the U.S.A., and it will take two weeks to get.

I checked on the internet, and various vendors offer an aftermarket voltage regulator for about $160.00, so tomorrow morning I'll get one ordered and on the way to me.

In a few days, when I receive the new voltage regulator, I'll install it and post the results.

[allegro5]

Hi Jim and members, I also have the Propane 6.5 Onan on my 96 Dynasty. Had the sme deal, runs real nice and no elect. Had a Mechanic check it! He feels it is the Voltage Regulator! I sent for one at Flight Systems ant its $225. Model 300-50826. It should arrive todat. You can Google that company and there is a Complete Manual ! It says to > Checking the Roror DC resistance is very important before installing a new Regulator! This is your best chance to find out if there is a problem that caused the last VR to Fail! Unplug the VR and Measure the resistance between Pins 9 and 10 on the 12 pin plug that goes to the VR. It should be between 23 and 28 OHMS! A reading much less than 23 indicates a Partial Short in the Rotor Areading much higher than 28 indicates a problem with the Brushes, slip rings or a bad connection. The most probable problem is dirtyor oxidized slip rings, so check them first! Clean if necessary!> That being said,( Coppied) where and how do I find the slip rings and brushes? Excuse my spelling! allegro5 greatallegro5@aol.com

[jimkate]

Bill,

If you remove your air filter (a square plastic box held on with one bolt), that will allow you to remove the small square plastic cover plate from the top of the generator housing. Then you will see the white plastic brush holder with two brushes in it. You can unfasten the brush holder wires, and remove the brush holder unit. Then you can look at the slip rings on the armature that the brushes push up against. If you tape a little scotchbrite on a stick, you can use it to gently polish the slip rings while the engine is running.

If you do that, and the tests you are talking about show that
everything is OK, the generator should work like a dream.

Once put back together, it is important to make sure that the engine is running smoothly, not surging, and the engine RPM is correct. It should run at 1800 RPM under load.

[allegro5]

Jim, I wrote all that down, thanks again! Allegro5. Ps, did you say the name of the Company where you ordered the Regulator? The Onan dealer in Mass. wanted $398 and would not tell me the Part numbers! As I said, I got one and loads of info at Flight Systems! You even did better!

[jimkate]

Bill,

I ordered my regulator from Advanced Service and Parts.
Generator parts, Generac, Kohler, Onan | Kim Hotstart heaters, Sensaphone, Freeze Alarm, LG / LS contactors

The voltage regulator was 169.00.

The folks there are VERY knowledgeable, very helpful, and with the regulator they supply a complete instruction manual for tuning up the generator for maximum performance. They specialize in all parts for our generators. I will definitely call them again.

Cummins-Onan here in Canada wanted 583.00 for that regulator, and had no stock. They wanted 15% to order one in for me. I thought that was a fine example of wonderful, caring service. So I went elsewhere.

[jimkate]

The generator is fixed. I learned something. The voltage regulator burnt out, that's why the generator quit working. However, the voltage regulator burnt out because the generator slip rings had oxidized badly enough that the brushes weren't making good electrical contact with them. Cleaned the slip rings with Scotchbrite, made sure the voltage was right at the brushes, installed the new voltage regulator, and a-w-a-y we go!

The generator now runs very well. I now realize this problem has been developing for quite some time.

Lesson - keep those slip rings clean!

[BigSkyBob]

Jim, I'm curious if you exercise your generator on a regular basis. With slip rings being copper, I suppose they will oxidize eventually no matter what unless it's used under load daily.

[jimkate]

BigSkyBob,

I use my generator a lot. However, I'm not the original owner. I bought this unit in the fall of 2008, and I've never been happy with the way the generator runs. Now it seems that it's going to be OK. Possibly the slip rings were already badly tarnished when I got the unit. If I had known that, I would have cleaned the slip rings then, which probably would have saved me a lot of aggravation, and would have prevented having to replace the voltage regulator. I count myself fortunate that there was no more damage than that.

[Jimmy F]

Well my generator, which is the same as Jim's, is working good, but for the time it takes, and given the trouble Jim has had, I think I will give those slip rings a bit of a polish... just to be sure!


Jimmy

[jimkate]

One thing puzzling me. At the volt meter above the door.

On shore power it reads accurately, whatever the line voltage coming in is,
that's what the volt meter reads.

On generator power, the volt meter has always wandered between 108 and 115 volts. Now that the generator is working better, the volt meter now wanders between 110 and 112 volts. However, at the junction box right at the generator, the lines test at a very steady 119.8 Volts.

I figure that it's losing about 8 volts somewhere between the generator and the voltmeter.


Should I be concerned about this?

[Jimmy F]

Jim

Okay I had time to work on mine today and here is what I found. The slip rings didn't look too bad but I gave them a clean with a Scotchbrite pad regardless.

On shore power my gauge above the door is steady as well.
On generator power it bounces between 110 and 120 volts and yet...

At the junction box at the front by the generator, with my digital meter it moves between 121 and 122 volts.
At an outlet in the kitchen with my digital meter it moves between 121 and 122 volts.
With my good old analogue needle type multimeter it is rock solid at 125 volts at the kitchen counter outlet. Never did check at the front with my analogue meter, however;

I then pulled out the panel above the door and put the multimeter directly on the connections going to the permanent voltage gauge that bounces.
With my digital multimeter it bounces between 121 & 122 volts.
With my analogue multimeter it reads steady at 125 volts.

Now it could be that the digital multimeter is too sensitive and/or the analog meter isn't sensitive enough...I don't know, but I do know that the power isn’t fluctuating as wildly as the Monaco voltage gauge would suggest.

Jimmy

[jimkate]

Jimmy,

Thanks. This would indicate to me that there must be some kind of fluctuation in the generator output that the Monaco volt gauge has trouble reading, so it fluctuates. Only thing that makes sense to me.