Resetting the Magnum Inverter

Yesterday, all my troubles seemed so far away. After spending five hours to resolve a problem that only required the press of a button.

Such is the state of the technology within our coaches. Documentation is either missing or incomplete. And that was the case in dealing with our inverter issue.

After the “AC Overload” issue happened, I immediately referenced the manual that came with the Magnum inverter. Nothing to be found there on an AC Overload. I called Magnum. They were closed and they would not be open for another 4 hours.

I consulted my good friend, Google. There were so many people that had run into issues with their inverter. Although I did not find a specific reference to our situation, a consistent theme around resetting the inverter as a potential solution emerged.

I consulted the manual again. Here is what it said:

4.4 Performing an Inverter Reset
Certain faults require that the inverter be reset. To perform an inverter reset (also known as a soft reset), press and hold the Power ON/OFF button (see Figure 4-1) for approximately fifteen (15) seconds until the Charging/Inverting Status LED comes on and flashes rapidly. Once the rapid flashing has begun, release the Power ON/OFF button. The Status LED will go off after the button is released.

“Certain faults”? They might be certain but they are not documented in the manual. Perhaps our AC Overload was one of those certain faults? I decided to perform the inverter reset.

Our Magnum inverter is located in the basement of our coach. It is mounted, upside down, between the main support rails of the chassis, in one of our slide out bays. The only way to get in there is to empty out the contents of the slide out and go in, back down, and attempt to work in a highly constricted area. I could barely get my hand into this area of the inverter. Newmar: why oh why did you put the inverter in this location?

It turns out that the reset process may require another button to be pressed. I did not find that out until 5 hours later. It cost me roughly $200 USD to learn that lesson.

I had little recourse but to bring in a mobile RV technician.

He followed all the same steps that I had already performed.

His conclusion? A bad inverter.

My suggestion? Let’s get Magnum on the line and make sure that we haven’t missed anything.

We called them and when we finally got Magnum support on the call, they told us about a second button on the unit. This one, an AC Input Circuit Breaker, marked number 16 in the manual:

When I had first reset the inverter, I had seen this knob sticking out on the other side of the unit. The markings were similar, CB INPUT 30A. It never crossed my mind that I needed to press that button. There is nothing documented in the manual about this circuit breaker. There is nothing to indicate that it needs be reset.

If I had pressed this button, it would have restored the functionality of our inverter immediately.

There are some steps to troubleshoot the inverter problem that I haven’t covered. They involve using a voltmeter to confirm DC power to the inverter and to confirm AC power from the circuit breaker box down to the inverter. I also reset the main controller by unplugging and replugging that component.

When the inverter sensed an AC overload, it somehow lost its way and it needed a reboot including a reset of the 30 Amp circuit breaker. Turns out that there are two circuit breakers for this system. One in the main fuse box and one on the inverter.

To resolve our issue required two button presses. One to reset the AC Input Circuit Breaker on the unit and the other to reset the inverter.

What was the root cause of the issue? I do not know. What created the AC overload issue to occur was the simultaneous use of a Microwave, kettle and toaster being run off the same 15 Amp circuit. That action should only have tripped a circuit breaker. I have no idea why or how it wound up causing an AC overload issue on the inverter.

If something like this happens to you, check with Magnum first. Your inverter may be fine.

Our inverter was fine and everything is now operating as before.

We won’t be running the microwave oven with the kettle and the toaster at the same time on the same circuit in the future.

I will be happy not to see an AC Overload issue again.

6 replies
  1. Bill Cooper
    Bill Cooper says:

    We just had the exact same issue. Ours was an electric skillet, toaster and microwave. Fortunately we found the reset button with other Tiffin owners. I too do not understand why the circuit breaker didn’t just pop

    • Rick
      Rick says:

      This article just saved our life and hours of frustration! Same deal…microwave, coffee pot, and toaster at the same time. Been living off of battery the entire day and didn’t know the inverter was disabled. The reset button did nothing alone!

  2. Darren Lehne
    Darren Lehne says:

    Thanks for posting gang!…This happened to me Friday and have been scratching my head for two days! Hopefully i can cancel the service call when I get back to the lake!

  3. Alex
    Alex says:

    Thanks for posting this! It happened to me as well, and I was able to fix things within the same day by following your instructions. Great post!

  4. MaeJune
    MaeJune says:

    Are the buttons labeled 15-17 on the top if the inverter? If so that would explain why it’s mounted up-side-down.
    Our Dynamax is mounted up-side-down as well.

  5. Larry Janacek
    Larry Janacek says:

    I may have the same problem and will be going out to check it shortly. I have a Magnum ME2012-20B inverter/charger which per the manual looks as if it has the same CB, 16 & 17 as you have shown above. This is in my 2017 Thor Palazzo 33. When driving I am not getting AC power to my refrigerator, but I do get it when plugged in and with the generator running.
    I do have another issue that may or may not be related and maybe someone can answer. I just had to replace all four of my 6 volt batteries. I have been out in the desert for 4 months and did not check the water in the batteries and suppose that may have caused them to go bad. The mechanic that replaced them said that I am getting a battery charge from the inverter with the generator running and when connected to ground power, however I am not getting a charge with the engine running. Do you know if there is an external relay, or something in the inverter/charger that is preventing the charge? I can’t seem to find any info in the Magnum manual that references that.


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