Some devices (like laser printers and other electromechanical servo controls) need a true sinewave power source because they use phase-fired SCR control circuitry. Phase-fired controls do NOT like anything containing square waves, like the power from "modified sine wave" power inverters.
Modified Sinewave is a marketing term to "sound" like you are getting something close to a sinewave... It is actually better described as a "step wave" output waveform. The typical chinese "modified sinewave" inverter has only 2 steps which crudely satisfies only the peak and average voltage values of a sinewave. (See Hotdram's pic...)
Higher quality stepwave inverters use more and finer "steps" to more closely approximate a sine wave. Even so, without harmonic filtering, those smaller steps can still wreak havoc with some phase fired controls. Too many harmonics...

Getting a bigger modified-sine inverter is still not likely to ever satisfy your printer since it fundamentally doesn't like the taste of the power.
Your inverter can handle the watts, but can't provide a pure enough waveform for the picky load to accept it.

It will require a REAL sinewave inverter with enough "grunt" to provide pure sinewave power even at the peak load.
They aren't cheap.

 

Take a look at a few of these sites for an idea of size and prices.
http://www.roadtripamerica.com/dashb...-Inverters.htm
http://www.donrowe.com/inverters/puresine.html
http://www.samlexamerica.com/pure_si..._inverters.htm
http://www.xantrex.com/web/id/176/p/1/pt/8/product.asp

This ought to keep you occupied for a while...

K.

 

They made me write all of my citations by hand when I was in FTO and for a few months after. Once I got certified on the computer though, that was all over except for certain charges. Anyone we arrest, we still have to write them out.

While the computer is good, I have noticed that I tend not to look up as much as I normally would when on a stop, which is something I've really had to work on.