Got it apart to have a look and its ugly...

16 blown FETS , the drive circuits, and even melted board traces.It doesn't get worse than this.This is going to be about 60-70 dollars in parts and a awful lot of time. Back in 2006-2007 this was a 1300.00 dollar inverter, I got it for 999 on sale back then.....its worth it to me to fix it up and then keep it as a spare. I will order in the parts then this will be a next winter repair project, in the mean time I will keep looking for a new one.

Well after a day of researching whats on the market, I am very impressed by how much more affordable everything is and how much better the performance is.
One product has stood out, with design performance that's unmatched and that's a AIMs inverter. Their 2000watt pure sine (also a 3000watt model), high freq inverter aimed at the industrial mobile market looks like a dream come true, I suspect this one is going to find its way to my place.
http://www.theinverterstore.com/2000-watt-pure-sine-inverter.html

Look at the specs on that unit!! The lowest idle draw I have seen on any pure sign wave inverter, and serious thinking went into the design in order to get 95% efficiency in the 0 to 666.66 watt range (one third of 2000), thats where you want your max efficiency band if running off batteries. The input range is a full 7 volts before shut down, 6 volts rapid fluctuation with output regulation at 3 %, and this unit will operate at full load to 176 degrees F. It has a 4000 watt surge capability, thats 1000 more than my last inverter! and its half the price of my 10 year old one, on sale for 499.00 right now. I don't understand their marketing department though, its clearly built for rougher environments, humidity, temp, vibration like in trucking fleets and Ambulances, but they did not get it certified to UL 458 standards that a fleet purchaser would likely look to see before ordering...I don't care but I think it will hurt their sales into such markets if they don't, they should be pushing this to the off grid market...So this is the front runner that I am considering so far..They do have this type in a 3000 watt continuous with 6000 watt surge but I have found I have no need for one that large, though it would be nice to have a little more head room....I could be running my maxstar 150 burning rods in the garage while the dishwasher is running with the 3000 watt unit...I will have to give this more thought...

The low freq inverters have come way down in price as well, and if everything was equal I would be buying low freq, but things are not equal, http://www.theinverterstore.com/2000-watt-pure-sine-inverter-charger.html This looks like a great unit, great price, and I am thinking about it, 2000 watts cont, with 6000 surge for 20 seconds, it sounds great but the damn idle current is more than I want, over 3 times that high freq unit (.7 amps) I have my eye on.(28 watts/12nom=2.3 amps at idle!!)
And just for funzies have a look at this monster... http://www.theinverterstore.com/4000-watt-pure-sine-inverter-charger-120-240-vac-60-hz-charges-with-120-vac.html

This is a split phase inverter so you have 120/240...A great powerfull unit, and just what solar installers like to sell....but this is also a example of why I try to stay at 120 volts only, and advise others to get rid of 240 volt loads or dedicate them to a generator...look under the spec tab....idle current (just turned on) is 50 WATTS!! doesn't sound like much does it, but that adds up in 24 hrs that's 1.2 kwhrs a day! its drawing 4.2 amps just turned on! That's 100 amphrs a day just to power up the inverter only! That's 6 times more power than that 120 volt high freq unit I am thinking about buying...In Alberta with our great long sunny days through the summer you can get away with that kind of draw but come winter when batteries rule, that can kill you power wise. Because you usually design your system for the worst conditions like winter, if you wanted enough battery capacity just to carry this inverter only for one sunless winter day you would need to dedicate 4 T105s (assuming 25% discharge ony) to running it.
If you live on batteries, idle current, or low power draw is the most important thing to look for.

I pulled the trigger and a new inverter should be here in 10 -12 days.... same manufacturer as my last one...nothing wrong with my last one, its failure was directly attributable to it owner, who modified it and then used it harder than it ever should have been used. This time I will behave myself and use it only for normal household stuff ....no more driving 1700 watt 16 inch diameter abrasive chop saw blades for cutting steel, or for air compressors , or running hydraulic log splitters, or hardest of all welders (120 volt stick and mig) The price has come down, I spent 500, and change. Not bad for a inverter in pure sign with a idle draw of .8 amps dc, or 10watt idle draw, that will run my whole house just fine. For those other items I will be picking up a second inverter from a fellow on my way down to olds to pick up my seed potatos, a 3000 watt mod sine, with 5000 watt surge. Brand new in the box for 200.00. This one is the one that will drive my heavy nasty loads, like welders and chop saws. So I will be all set up again with a heir and a spare. As much as I loved those low freq inverters especially the MAGNA SINE ones. The cost for me is too high and the idle currents they draw is just to much (for me).....My cost will be 700 and change for two units. Not to bad I think.

In reviewing specs on inverters, and reading reviews I came across this guy.. https://www.youtube.com/watch?v=IZac687CKAY&t=559s
It a four part review of 12 inverters he owns and has used..his evaluations seem bang on to me..The link I gave is where he is reviewing my all time favorite inverter (even though its mod sine). If you have a interest in the topic start at his part 1 review and watch them all, he points out lots of little things to look for in inverters and consider.

A add appeared on kijiji yesterday for a Go Power 3000 watt pure sign inverter. http://gpelectric.com/products/3000-watt-pure-sine-wave-inverter From the pictures on Kijiji it looked pretty beat up and dirty, but these things have a list price of 2000.00 dollars and I don't think I have ever seen a sale price less than 1600.00. The asking price was 175.00. So off to the big city I went. A business owned it, they let me test it, and this is another good reason to have a kilowatt meter, I could plug it into the inverter and check output freq and current as I tested tools with it. It ran everything so I handed over the cash, I didn't try to dicker around on price.
I have a good idea why they sold it, I suspect after a bit of use the unit would overheat and shut down, Shutdown cause it was so dirty inside! I suspect no one there could be bothered to blow it out so the boss said get rid of it...just what I suspect...anyway I already have it on my healing bench, knocked apart and ready for a good cleaning!! here is a picture, and look how dirty it is inside, unbelievable! The bottom of the case should be yellow but its black with dirt!

I think I just got myself a nice 3000 watt sign wave, with 6000 watt surge, inverter for a real good price! Just need to clean it up

Looks like you lucked out! Things are perceived as disposable, especially when owned by somebody else (company).

I feel lucky, but I still need to run it for a good bit just to make sure there are no problems. The pure sign inverter I ordered is in transit, I will be picking up a 3000 watt mod sine Tuesday so I have gone from being inverter poor, to inverter wealthy.

I have been using this Canadian tire 3000 watt inverter that was loaned to me for a week now...Let me first say this has run everything in my home.You can look up youtube vids of guys running 2700 watt heater and lighting loads to it....it does work. If you are someone who is worried about power failures, and if your cheap like me... I just have to say why don't you have one? Get on kijij, craigslist and sites local to you. These can be found new when on sale for 200.00 dollars...or on the used sites for 80 dollars to 150 dollars, right now you can find them all over Alberta in that price range. I know cause I just checked...no excuse not to have one...The 80 dollar one is in Red Deer...It can save your bacon in a power failure I am not kidding, hook it right to your car battery and run the a power cord right to your freezer....get it...save your bacon.

Now having said that.....And even after saying if you don't have one, get one....For those with finer tastes in power, and a little more wallet capacity.. I am going to say what a piece of crap, compared to previous models from Canadian tire...I don't think I have ever used such a high capacity inverter with such poor load regulation...there are better models out there. Its not just load regulation that's poor, this model has a little fan that's always running....it wont bother you the first day maybe not the second but after that it will....its annoying....
The voltage display is off by .2 volts, The wattage rating is off too ( a little). I am not going to miss this one when I give it back. I will post a pick of one of the mod signs I do like ( more than this one) when I pick it up but they do cost about 100 more on the used market, so 200 to 300 range.

So when I finally went to Penhold to get my potatoes I missed out on that inverter I was going to buy, a guy got there just hours before me...oh well, I went back to Kijiji and bingo I found another good one...130 dollars it cost me.

Yes, that's the same as the two I lost in the fire. They don't makem like this anymore. Some of you might wonder why would he would want a mod sine inverter when he already has a pure sign, and the answer is, this is a really good mod sine inverter, there dirt cheap to have as a back up, or back up for your back up, the build quality is outstanding internally, and very easy to fix if something goes wrong, not that I have ever heard of a failure of one of these. I opened this one up to check it out, and I will show you why I like this one so much. Test question at the end.

First look at that picture above, the thing is massive, and heavy...no plastic in the case at all, its completely metal, its its own emp cage, and that means no interference with your radio or tv. It is able to dissipate any heat through those ribs on the exterior very easily.

Here is the centerfold....

Just look at the picture....and I will narrate for you....your looking down onto one of the two boards in this unit....This would I suspect be called the main board, and the one that does the heavy lifting....the first thing you should notice is the relatively fewer parts on this board as compared with a sine wave inverter, in fact way fewer....fewer parts makes for fewer things to fail. Imagine the black and red wires out of the way and then you can picture just how few components there are. Its so well laid out that just by looking at it we can figure out how it works and what each part does.... Note that there are 3 main sections that are identical on this board, each with a transformer (yellow thingy) note how the middle section has been rotated 180 degrees with respect to the two end sections. If you had just looked quickly at it you might have missed that the sections were identical and not caught that the middle section was the same just rotated.
I have a theory why the designer did this,and he didn't have to, just my theory I may be wrong but we know that the transformers need to be pulsed( switched on/off) that means (as they do now days) fets are being switch on and off very quickly, if everything was orientated the same way then all the fets would be mounted on the same side of the aluminium case ( lower side in this pic) But by switching the middle section around one group of fets can be mounted on the other side of the case, thus keeping all the fets cooler by increasing the surface area that they can dissipate their heat into. Its just a little detail but it shows some good thinking went into the design.
What else can you see?....note the 3 groups of 6 capacitors, note that each group is at the end of the transformer that has the big heavy silver straps, they need to be heavy straps because that end of the transformer must handle the heavy current from the battery, so we have identified the primary side of the transformer, and identified the input capacitors...all just by looking. Now because the picture is shrunk you might not be able to see this but just by looking I can see that all the primaries of the 3 transformers are in parallel...So this leads us to the thought that if they are in parallel then each transformer carries one third of the load...its rated as a 3000 watt inverter so at full load each of the three sections must be able to handle 1000 watts, seems like a reasonable conclusion ...right? of course.

Now look at this...we can see that each transformer has 4, 30 amp fuses in parallel protecting the primary side....what can we deduce from this...

Well each transformer can take 4x30= 120 amps steady before a fuse (all 4 at once) blows, that means because there are 3 transformers sharing the load then the inverter can draw 360 amps steady state without blowing a fuse, and that means its reasonable to assume this unit can be considered to be a (360 x 12 volts) 4320 watt surge unit, its actually more because those fuses are slow(er) blow fuses, but we are just reaching reasonable conclusions from what we can observe at this point not looking for technicalities.

( just back to add that I found the manual on line and they rate this unit as a 5000 watt surge)

Note that the transformers are not just soldered to the board but actually are also siliconed in place, you can see the white silicone under that middle transformer, and my pictures don't show it but the capacitors had hot melt glue put on them then they were placed on the board and soldered in....again good build practices.

MORE LATER

I didn't notice any SMD components in there at all...very few components at all actually! This is going to be easy to stock spare parts for it.
Nice grab.

There is a couple smd parts, a few passive components in the control section That I circled and identified as #6... the build quality is so well thought out...note how far away the capacitors are mounted from the transformer, This distance must be three fingers wide, these caps will never be stressed with heat from the transformer, or the fets, now days they pack everything in like sardiens. I think this was designed roughly mid 90s? I am only quessing...I know I first used this model roughly around 2000, to run tools off a truck. The design hints to a engineer who had real world experience in making a good product. also by moving the control section away from the fets, you "almost" guarantee you wont get a cascade failure back through the drive circuits if a fet lets go. Unlike in my inverter that failed in the first or second picture in this thread and the DC arc from the fet reached out and cooked everything it touched in front of it .

I circled what I think are the major groups in the power circuit...number one is just a large input cap bank, 2 is where the 4 fets are fired in parallel to switch the 12 volts to the primary of the transformer, 3 is the transformer that takes the now pulsing 12 volts and turns it into roughly 150 volts (peak) AC, that voltage is fed to the two diodes marked as #4, that change the AC to DC, and capacitor # 5 filters out the ripple. Thats pretty much all this board does and its so well laid out that this is all self evident, The output of each of the 3 sections is combined right at that capacitor in section #5, and then this voltage, lets say its 150 volts DC, I am only quessing, is fed to the second board on the white and black wires that I drew arrows on.

I think I was to quick to say the fuses were to protect the transformer, I don't believe that transformer could be damaged, rather I now think they are there to blow if something goes wrong with the fets, 4 fets, and four fuses, makes more since, but I am not going to open it up again to check further. I would bet those are 30 amp Fets if I am right. Also note how far apart each group of 4 fets are from each other I suspect if a fet failed, on the primary side of the transformer, at worst you would lose up to the four fets in the failed section but not more, and none from another section.

I will look at that 2nd board Saturday.

I should mention this inverter also happens to be code approved for hard wiring into your home, for those who care about such things, I don't myself.

As per the code,

The inverter must be a certified product. CSA 22.2 107.1 IEC62109-1-2 (coming soon)

looky at the picture, right on the back is the csa number and the stamp

This is the only other board in the unit, and as we can read on it, it says DC to AC board, how thought full of them to tell us. All this board is doing is flipping the polarity of the DC back and forth 60 times a second to make AC (or is it 120 times?). If I am not mistaken that is nothing more than a classic H bridge.
4 control fet groups (groups of two) on the heat sinks. And look at the gate lead resistors, strung way out there........like they are approaching something dangerous, that could bite them. Lots of room there so if a fet lets go the damage doesn't propagate. I like it. And the center section of the board isn't populated on the left hand side, as I suspect this was a generic board used in 240 50 cycle units and 24 vdc units, so they only populated the section needed for 120 volt 60 cycle....so much room and space on these boards I could park a bus on them.

My new sine wave inverter that I ordered.....defective right out of the box...I have to send it back...think I will crack it open first to have a peak inside. I will run my house on the above unit while I wait for my replacement one to come.

Always great to read your posts on machines, electronics and all. I have nothing useful to contribute on these topics, and I assume this is the case of many hence the few replies, but the posts are well done and I'm learning lots. Thanks again.