Problem with inverter

[mettleramiel]

Ok guys, today there was a severe thunderstorm in my area. Now, the house was not struck, but immediatly after the storm, I tried to turn on my Sima SPV-10 100watt inverter and noticed a serious problem. It turns on fine, all the lights go on (except the warning ones), the remote switch still works, the fan will turn on but no AC is coming out of it. I opened her up and can't see any blown caps or other obvious damage, however, I did notice that some of the fets have a copper look to them whereas a couple other ones had more of an aluminum colour to them. Perhaps some of these are blown? Here is a blurry pic to help

Any other ideas would be apreciated. Oh yeah, the inverter was not turned on during the storm. Perhaps it's not related, but I thought it seemed to be a little too coincidental. Thanks for the help, people.

[ghurd]

Are the different colors different part numbers?

Some have 2 kinds of fets which could account for 2 colors.

The four TO-220s on the left have 2 legs, maybe Schottky diodes, maybe more chance of them being ruined by high voltage?

Not that any of it helps.

G-

[mettleramiel]

Oh, damn you're right. They have completly different numbers on them.

[GeeMac]

Good Gawd man!! It was and EMP!!

[Flux]

Unless you know enough about electronics to break into the circuit and find the point of failure you might as well bin it.

If you have some knowledge then you should be able to see if the dc converter is running, check for the high voltage dc buss and if that is present you have a fault in the ac bridge circuit.

Without knowledge and circuits its likely to be a fruitless task.

Flux

[dnix71]

That looked kind of large for a 100 watt inverter. I Googled the model and it says 1000 watts with soft start.

http://www.zalmar.com/detail-Misc-Sima-STP_1000.htm

Maybe it's the soft start circuit that went bad. The link I posted has one for $115 plus shipping.

[dnix71]

And here is the model that superceded it for $122

http://www.powersystemsdirect.com/Sima/1000_Watt_12V_Titanium_Plus_Power_Inverter_STP-1000_1386.php

[Opera House]

I buy defective inverters and repair them.  Usually when the output shorts, they go into a safe shutdown.  Here is an easy way to check the FETs.  Use a digital ohm meter and measure resistance between the two outside legs of the FET.  Under a couple ohms is a defective FET.  These generally have about a 100 ohm resistor isolating the gates of parallel FETs.  The gate almost always shorts in a failure.  In the H bridge output, the defective FET can be just wiggled till the leads break.  Generally two fail at a time.  You can now use this no solder repair at half the rated power.  Failure on the multiple boost inverters can be trickier.  A short on these FETs can often take out the gate driver transistors.