[SMCARA] Pure sine wave inverters

[Jim Wieldt]

Hoping to find someone who can enlighten me on the pure sine wave inverter if not certain features of consumer electronics.  

I have two inverters, a modified sine wave and a pure sine wave.  Not sure why they call one modified as I am led to believe that it is as square a wave as they get.   The pure sine wave had been attested to be really true to the form by Amazon purchasers feedback; one claimed he had had it on an oscilloscope.  It is a 1000 watt (2000 watt surge) MicroSolar unit that wasn't all that expensive compared to others on the market which looks to be centered on the solar power business.  I am into these things as a means of getting through our frequent power outages more comfortably and have tired of candles and kerosene lamps after I have shut down my propane powered generator for the night.  

My surprise came when I tried to power up some of my stuff.  Power source is a new group 75 battery from Advanced Auto Parts.  A flat screen Coby worked beautifully on it but not so with my Magnavox DVD/VHS player.  It never powered up and when I put it back on wall power, it still wouldn't until several minutes later and then it was normal operation again.  I repeated this several times with and without anything in it to launch and play.   It was like an internal thermal fuse tripped and later reset.  I tried another DVD/VHS player and it played sometimes but not often.  More often when it was interfaced with a power strip.  I think that a curious thing about all three devices is that they take some power even when turned off.  The TV I am absolutely sure of that and one of the players as well. Possibly that is how they remember where to resume on a DVD being played and staying warm to come up quickly.  

The only physical interface difference is that the Coby TV had a three prong grounding plug and the players had a two prong polarized.  The power strip also had a three prong ground plug.   All of this makes me think that it is a grounding thing but my inverter doesn't have a ground provision per se.   

I made an inquiry to an online inverter store and all I got was that none of their inverters ever did that.  

Naturally I have become reluctant to plug anything of value into it until I find the key to success.

Along this line, can anyone recommend a good value oscilloscope for relatively low $$$ ?

Regards, Jim Wieldt  KC3FHS.