Onan QD7500 Inverter

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.
See posts with no answers
Section 10 of the Onan 7500 service manual is titled "Controller-Inverter Service and that is the module they are talking about. Inverter and control circuits, all in one box. "service" is diagnosis of problems, followed by "replace".  I'm sure there are things inside that a competent tech could repair, but high tech labor is expensive and they don't sell sub-assemblies anyway. If something inside is obviously burned out, most any electronics tech could solder in a new component, but whole boards are probably not available for swaps.
 
I just got the whole inverter out this morning.

After removing about a million screws and finding a way inside part of it, I find a board with a severely burned section over an inch long and about a half inch wide -- several electrical components are involved.
Therefore I am considering the board as "Toast/Dead"
The board has a number -- 300-5030, which I have searched for with no luck other than finding one that sold a few years ago from an inverter that someone took apart.

I will continue to search for that, but am skeptic I will find one.

At the very least it does confirm to me that the problem is the "controller/inverter" and not something else.
I would hate to spend hundreds of dollars. put in a part and not have that the problem.

Still pursuing a used Inverter if the price is right -- otherwise it will be a new one.

thx -- Dale


 
Update == I purchased a used one on ebay ===waited about three weeks, asking recently for shipping info from seller.
Just got a reply that generally says -- "Gee,  I have been sick and on vacation and hope to get to my place to get it shipped next week"  what BS
-- so it has not even shipped yet -- NOT HAPPY about that.

Here is the interesting part.
I filed a complaint with Ebay -- they got involved, and in a little more than a day the full amount, including shipping, has been credited to my PAYPAL account.
I assume they will either communicate with seller or write it off.  It was about $950.

My next step will be to do what I thought about initially -- buy a new one from CumminsOnan --
I plan to call them tomorrow as I really need this installed within about a week or so, when I go on a four day trip to Sebring Raceway

Will keep this updated.  thx Dale
 
Yes Gary === they are not cheap
Cummins Power South has them for $1599.
I will go over to them today and order it locally so the shipping is free to get it from their Orlando warehouse, and pick it up 10 minutes from me.
I will have to pay Florida Sales Tax in any case.

Another interesting thing is I have seen several listed on Ebay as new -- for $1899
Why would you pay more on Ebay than you can from the dealer.
I am starting to see that more on Ebay -- I guess people just don't do any research and assume the Ebay is the cheapest.
it might have been at one time. but it is not always today.

thx Dale
 
I had mine done at Rocky Mountain Cummins Las Vegas five years ago when the labor rate was $116.00 per. It included teardown, inspection, replacement of the inverter, and reassembly.. I reinstalled it in the motorhome and its been great since with 2300 hours on it.>>>Dan
 
my Inverter should be here tomorrow -- one day after being ordered.

Here is my question.

There are six wires leading out of the INVERTER to the actual Generator coils

There are TWO RED. TWO WHITE, and TWO BLACK
the inverter ends are all female connector ends with no specific markings.

I assume each set goes to an area of the generator coils.
I see no way to establish any polarity on these connections to ensure each red goes to the proper red on the generator.
Therefore I am assuming that polarity is not important on these.
Meaning -- just connect the reds on the Inverter to the reds on the generator,  whites to whites, and blacks to blacks.

any thoughts by knowledgeable electrical people 

thx --- Dale
 
I found my answer after thinking and researching some more.
Yes - it would make a different if the two reds were switched --etc

Looking closely at the wiring diagram, and then the wires, each one is separately labeled in print on the wire
they are labeled as T1-1, T1-2, T1-3. T2-1, T2-2, AND T2-3. on wires leading to the windings of the stator, and are also marked like that on the Inverter

Problem solved -- just match the wire labels.

thx
 
 
There are actually two inverters, T1 & T2, so you have two sets of three leads. You definitely don't want to mix the two sets, but within a set  the colors should match up with the 1-2-3 labels. The inverters get their DC power direct from the stator/armature and produce 120v for the genset output (2 hots and one neutral).
 
yes Gary --- I looked at schematic of two stator Y connections --so had decided exact wiring was very important.

I picked up the Inverter from Cummins yesterday and installed it today.
Took about 3-4 hours total. All wires matched no issues.
Started right up on the first push of rocker switch.
Check it for leaks/fluid levels/put covers on, and ran under a load for two hours.
No issues at all ---

I am glad that Saga had ended
 
Hello Dave,

I have a similar problem with my ONAN 7500.  I have also pulled out the ton of screws and gotten to the top board - where I found a smoked spot on the housing and the top of a capacitor burned off.  It seem quite isolated, nothing else seems damaged, just a little solder splatter from the capacitor.  Do you have a picture of the board that you had the problem with?  I am wondering if it is the same spot (top of the board between the two connectors and slightly aft.

Best,
Steve
 
I don't have a picture, and I just took to old Inverter to the electronic recycling center yesterday.
However -- I do did look at the board again before i recycled it.
The burned area was between the connectors and in an area about two inches long, parallel to the wires coming into the connectors.
There were several resisters and capacitors fried.
It does sound like the same area.

good luck with your simple component replacement.

As I mentioned I ended up getting the Inverter directly from Cummins/Onan, for about $1500.

I recently ran mine a lot for five days of no utilities when at a sports car race -- no issues at all.

talk care --- Dale
 
Hi Dale,

I did repair the visible damage, but the same results - error 13 and the output voltage is just 70VAC prior to the automatic shutdown.  I am probably going to have to get the new inverter/controller from Cummins/Onan - they are giving me a quote of $1,599 - ouch!

There is a pure sine wave inverter in the system - I wonder if any of that can be salvaged.

Best, Steve
 
Hello! I need to replace the big transformer inside the controller/inverter. Anyone have an old controller/inverter they wouldn't mind parting out? Part# P/I 2255-00, 0315-0820. It is held in by two torx screws.
Alan
 
I am opening my old thread to see if anyone has any new comment,
particularly about sourcing parts -- Onan 300-6058-02  INVERTER/CONTROLLER

My Generator died again at the start of the same trip as last year.
I am not sure it is the inverter/controller but I am getting the same symptoms.

One year and back to this again.

thx Dale

 
I decided to take the RV to Cummins Coach Care (20 minutes from me) since they are nearby and that is where I bought inverter.
Am having them just diagnose "no start" at this point.

I took in all reciepts for purchase of other inverter.
Got the feeling they thought that if it was the inverter it would be covered.
Warranty is one year or 100 hours -- neither of which I have exceeded.

We will see === thx Dale
 
Well to close this saga the second time --(I Hope)

I had the Onan Generator worked on at Cummins Power South (Riviera Beach FL address) a Coach Care Facility.
They diagnosed the "No power/No Start" as a loose wire inside the Generator cover connections.
They charged ONE HOUR for diagnosis/repair and also said they replaced some missing bolts from the cover, and test ran the generator for one hour.
Total bill with Tax -- $159.
Not bad -- good to see they were honest about the repair.
That is the second time I have had work there and I have been satisfied both times.
They have about 6-8 RV's in there at this time, and said they do a lot of seasonal work just before people head North with their RV.
Highly recommended. 

I just ran the Generator for another hour under load when I got it home.

I hope this says fixed --- thx Dale

 
I'd like to reopen this. I see Steve talking about error 13 and 70VAC which is logical, I'm getting 146VAC and error 13 which is confusing. Still sounds like I will have to replace the controller thing, just maybe someone can clarify why I'm getting undervoltage error on high voltage on high voltage output
 
You must log in or register to reply here.

Latest posts

Members online

Total: 844 (members: 28, guests: 816)

Forum statistics

Threads
131,965
Posts
1,388,335
Members
137,718
Latest member
urnwholesaler
Back
Top Bottom