Grundfos Pump On Xantrex Modified Sine Inverter?

This sounds very strange. Send me an e-mail with more details at va7rv AT hotmail.com

Officially Xantrex has the position of Note: In order to protect our intellectual property, Xantrex does not release schematics, part lists or wiring diagrams to the public. Xantrex does not sell internal parts to the public. If you need an internal part replaced, your inverter will need to be serviced by an Authorized Service Center or at the Xantrex factory.

So your options are to ship it to an authorized Xantrex repair depot, or reapair it based on electrical knowledge in general

If you decide the latter approach, you have to see if there are any IC's or other semiconductors you can identify. If they are true sine wave inverters- the wave form genesis is what counts- you will have to locate the low frequency oscillator, if it will power up and you have an oscilliscope. you can see if the waveform genesis is a square wave originally, triangle wave or a sine wave. essentially move through the traces to see where the signal goes away. your failure point will be close.

If the original waveform is sine wave, applying class A, AB or B audio amplifier principles should allow you to effect repair.

If the original waveform was square wave or triangle wave- the wave form is shaped by an LC network. Depending on what sized Capacitors and inductors are inside of the cabinet will determine where the sinewave form was achieved. If they are physically small, the waveform was shaped off the Pulse Width modulation circuit, audio amplifier principles should apply in the circuit trace and troubleshooting with the scope.

if they are physically large- the waveform is shaped at the output device(s) Usually an IGBT or power darlington..

If you are working with a modified sine wave inverter, the principles and block diagram is similar to a Class D audio amplifier or a crude AM transmitter with none of the pass filters (oversimplification perhaps)

this ought to be either enough of a start or enough of an outline for you to determine how you want to proceed.

Are you using a true-RMS voltmeter to measure the DR's output? The DR's output is modified sine wave, and a cheap average reading AC voltmeter will give you a reading of 90 volts or so. Alternately, if you have an oscilloscope, you can verify that the modified sine wave is around 170V peak to peak. It should alternate in segments of -170, 0, +170, 0... The duty cycle and peak voltages will vary with the inverter load.
- Tom, Sun Electronics International, Miami, FL

Hi,

You could buy the control board from :-

http://cgi.ebay.com/Xantrex-Inverter-Repair-Board-DR3624-Control-Board-/260652658387?pt=LH_DefaultDomain_0

I hope i have been helpful.

Thank you!!

The output of this inverter (and most others) is a modified sine wave, which isn't quite the same as a true sine wave - like you get from a wall outlet. Unfortunately, most transformers (which is essentially what your laptop power-supply is) require a true sine-wave. Your inverter will work fine for many other 110V applications. You can buy an inverter with a true sine-wave output, but they are more expensive.

I highly suggest you invest in a good quality inverter. For most equipment either pure or modified sine wave is fine. I would suggest you install a line conditioner after a UPS for any computer products. The line conditioner stabilizes the voltage much more closely than a UPS will.
As far as building your own, I've taken apart a lot of UPS models which have a DC-AC converter in them and they are filled with lots of heavy heat sinks, transistors, resistors, capacitors, etc. You can usually find these very cheap since the batteries die but the converter is fine. Check the input voltage of the original unit and start from there to make one easily that has everything already assembled with minor modifications.

What kind of inverter is it and what kind of meter are you using to check the voltage with? If the inverter puts out modified sine wave, you have to use a true rms volt meter to accurately check the voltage with. A non rms volt meter will show a low reading.

The rms voltage is what counts, because it tells how much power the output will deliver to a resistive load. Inexpensive multimeters on their AC ranges are usually average-responding rms-calibrated meters. This means they measure the average of the absolute value of the AC component of the signal, and display that average multiplied by about 1.11 (actually, pi over sqrt(8)), the ratio of rms to average value for a pure sine wave. That way, the meter will give the right rms reading for a sine wave.

If the signal is a square wave, where the average and rms values are equal, the average-responding meter will read 11% too high.

Many inverters put out a modified sine wave (MSW), which sits at zero for a while, goes to a constant positive level for a while, goes back to zero for a while, and goes to a constant negative level for a while to complete the cycle. The positive and negative parts of the signal have the same magnitude and duration.

The rms and average values of an MSW depend on its duty cycle D, the fraction of a cycle for which the signal is not at zero. In a well-designed inverter, the duty cycle will be adjusted when the DC input voltage goes up and down to maintain the nominal rms output voltage. If we use peak voltage Vp to mean the magnitude of the positive and negative voltages the signal goes to, then Vavg for an MSW is equal to Vp times D, and Vrms is equal to Vp times the square root of D.

The duty cycle for which an MSW will have the same rms to average ratio as a sine wave is 8 over pi squared, or 81%. For any duty cycle less than this, an average-responding meter will read a lower voltage than the inverter rms output, and for a duty cycle higher than this, the meter will read too high.

If your MSW inverter is putting out 120 volts rms and its duty cycle varies from 50% to 75%, the meter reading will vary from 94 volts to 115 volts. I avoid the problem by using a Radio Shack 22-174B true rms digital multimeter.

Not to worry. First thing is you are probably not using a true RMS volt meter. You are reading an average voltage of peak. You have a sine wave inverter. The RV 2012 has a peak of 164 volts. I could go into much more tech detail but may confuse you. If you want to learn more her is a link from my dealer tech sheets. Also if you have checked voltage in a float state it will read high.
Hope this helps you
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Jerry

http://www.xantrex.com/web/id/325/DocServe.aspx

I'm not sure what the application is but I will offer the following. As a retired electronics engineer i can say for sure that a true sine wave does not have any harmonics in it. A modified sine wave will have some harmonics and other what I would call " trash content" depending on how it is modified.

Loringh