Onan 6.5NH 3CR 16604P - Bridge Rectifier

[xengineer]

I have this genset (Onan 6.5NH 3CR 16604P) in my '82 Excella 28' Airstream.

While exercising the genset Thursday, it quit produing AC. No circuit breakers were tripped in the service box inside the motorhome.. All circuits and equipment on them work normally connected to shore power.

I have experience with an Onan 6KW genset (NH 9000 "Powerdrawer"). When the AC output ceases on this model, replacement of the bridge rectifier, a ten minute job, frequently solves the problem. Does this apply to the Onan 6.5NH 3CR 16604P? Does it even have a bridge rectifier? If so, where is it located?

I have only the operating/maintenance documentation provided by Airstream at time of delivery... It includes no guidance on servicing the AC generator.

I have all of the manuals on the Onan 6KW NH9000. It does not appear, however, that they can be used to troubleshoot the AC on the 6.5KW unit.

Thanks for any counsel owners may be able to provide.

Fred Hudspeth (AKA "xengineer")
I982 Airstream Excella 28'Motorhome - Cooper Landing, Alaska
1978 GMC Royale 26'Motorhome (remanufactured) - Tyler, TX

[xengineer]

Further to my inquiry, the gen set has been used sparingly at only 176 hours. I have, however, done all maintenance at specified intervals.

Fred Hudspeth (AKA "xengineer")
I982 Airstream Excella 28'Motorhome - Cooper Landing, Alaska
1978 GMC Royale 26'Motorhome (remanufactured) - Tyler, TX

[345bill]

Just in case you haven't already, try here: www.cumminsonan.com

[bkahler]

Fred,

Check out Onan Generators - SmokStak and do some searches on your model number. There are a lot of good knowledgeable people on smokstak and have helped me out a bunch over the years. Many of them have copies of just about any Onan genset made.

Hope this helps.

Brad

[xengineer]

I went to SmokStak as Brad suggested. David C.on that forum provided scans of the Operator and parts manuals. Here is my reply to him:

For David C.

David,

Thanks much for the scans of the Operators and Parts manuals you provided. Problem solved.

On the last page of the Onan Operators Manual, there is a wiring diagram. It shows a circuit breaker in the control box. I finally found that breaker on the machine. It is in a very inconspicuous place on the control box between the engine and generator. It is behind the hour meter on the side of box out of sight from the front. There is no mention of this circuit breaker anywhere in the text of the manual. I had the Operators Manual but did not notice that circuit breaker on the wiring diagram until I studied your scans.

The breaker is marked 30 amps and it was tripped. There is a reset switch just above it. I reset the breaker and started the genset with no load. The AC output of the genset was then back to normal. It also carried loads of less than 30 amps total normally.

The genset is in a '82 Airstream Excella 28' motorhome. This is first time that breaker has tripped in the 15 years I have owned the motorhome. In chasing the circuits from the genset, I found that the 30 amp breaker is on the circuit that supplies 120VAC to the front overhead air conditioner and other "house" loads. The rear air conditioner is on a separate circuit from the generator. There is, however, no breaker at the genset for this circuit. When I was exercising the genset last Thursday, I inadvertently put more than a 30 amp load on the house circuit, causing the 30 amp breaker at the genset to trip.

None of this is covered in the Onan and Airstream manuals provided with the motorhome at time of original delivery. Fortunately, the prior owner left the manuals in the motorhome when I bought it.

I am filing the PDFs, especially the parts manual, you sent for future reference.

Again, thanks much.

Fred Hudspeth

PS - and thanks also to others who provided input on this issue.

[bkahler]

Fred, glad to hear you got your problem solved .

Its amazing how few hours these generators have for as old as they are. The Onan I'm getting ready to install in our 310 only has about 270 hours on it and its out of an 86 345.

Brad