Hello
I've received, for free, a defective Motomaster Eliminator 1750 watt power inverter. The circuit use a SG3525. It seem to be made by Xantrex and I can not find any schematic of this inverter.
Four of the IRF640 output mosfets are burned.
I presume that those four mosfets was connected in parallel, and one mosfet did goes unbalanced and have to much load and burned, after that the 3 others get all the load and burned ?
I can replaced the 4 burned mosfet, but I was thinking to put a .1 ohm resistor on each source terminal of all the 16 output mosfet for a better current sharing between all those mosfet, is it a good ideas ?
Thank
Bye
Gaetan
I've received, for free, a defective Motomaster Eliminator 1750 watt power inverter. The circuit use a SG3525. It seem to be made by Xantrex and I can not find any schematic of this inverter.
Four of the IRF640 output mosfets are burned.
I presume that those four mosfets was connected in parallel, and one mosfet did goes unbalanced and have to much load and burned, after that the 3 others get all the load and burned ?
I can replaced the 4 burned mosfet, but I was thinking to put a .1 ohm resistor on each source terminal of all the 16 output mosfet for a better current sharing between all those mosfet, is it a good ideas ?
Thank
Bye
Gaetan
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Attachments
Do not try to reengineer it without understanding it first.
Power the inverter with a current limited supply for initial testing. If nothing else, connect a car light bulb in series. Make sure none of the components are heating up.
It is possible that another component is bad which caused the MOSFETs to burn out, but it can also be caused by an overload, incorrect input voltage, or overheating.
Power the inverter with a current limited supply for initial testing. If nothing else, connect a car light bulb in series. Make sure none of the components are heating up.
It is possible that another component is bad which caused the MOSFETs to burn out, but it can also be caused by an overload, incorrect input voltage, or overheating.
This looks like a quasi-sine inverter and these blow quite easily because they always have trouble with big inrush currents and very reactive loads like motors. In most cases the MOSFET drive circuit is too simple to suffer damage and replacing the MOSFET is enough.
You should check that the drive circuit works and that the rest of the MOSFET are not damaged, though.
You should check that the drive circuit works and that the rest of the MOSFET are not damaged, though.
My dear friend you've not told us the details about the input transistors since from my view it seems to be employing smps and also informatio about those other ic's beeing shown in your photo.
Thus try to give adetailled information of other components.
Thus try to give adetailled information of other components.
Hello
It's a modified sinewave inverter, here is an image with all Ic numbers.
Thank
Bye
Gaetan
It's a modified sinewave inverter, here is an image with all Ic numbers.
Thank
Bye
Gaetan
An externally hosted image should be here but it was not working when we last tested it.
Hello
I have talk to the guy who did have this inverter before me. He told me that, by error, he plug a live 120 volt ac wire into the output plug of the inverter.
Thank
Bye
Gaetan
I have talk to the guy who did have this inverter before me. He told me that, by error, he plug a live 120 volt ac wire into the output plug of the inverter.
Thank
Bye
Gaetan
That's pretty hard to do "by error"....
Because that would require an extension cord with male plugs on both ends. What was he trying to do, hook up a solar or wind generator to the house electrical system? If that's what he's thinking, it needs to be a true sinewave inverter and synchronized to the power line. Otherwise, BANG!!!! Ought to thank his lucky stars that he just blew a couple hexfets.
Because that would require an extension cord with male plugs on both ends. What was he trying to do, hook up a solar or wind generator to the house electrical system? If that's what he's thinking, it needs to be a true sinewave inverter and synchronized to the power line. Otherwise, BANG!!!! Ought to thank his lucky stars that he just blew a couple hexfets.
I think he was trying to make a large UPS with the inverter. With his dangerously limited engineering skills, he probably thought that by connecting two sources in parallel, he can lose one and still have the load powered. Of course, although that will work to an extent with certain DC sources, it generally won't work with AC.
Hello
The first time I ask the guy it was quite short answer, so today I did phone again Robert, the guy who burn this inverter, he told me that he was using it in a big fifth-weel RV for camping, normally he do unplug the inverter from the 120volt system of the RV , before connecting the RV to the 120volt system of the camping.
He just forgot to unplug the inverter wen he did plug the RV to the 120volt system of the camping.
So it was just a plain forgetfulness from the guy.
I presume and hope that only the mosfet are burned, so soon I can have some IRF640, I will replace them.
Thank
Bye
Gaetan
The first time I ask the guy it was quite short answer, so today I did phone again Robert, the guy who burn this inverter, he told me that he was using it in a big fifth-weel RV for camping, normally he do unplug the inverter from the 120volt system of the RV , before connecting the RV to the 120volt system of the camping.
He just forgot to unplug the inverter wen he did plug the RV to the 120volt system of the camping.
So it was just a plain forgetfulness from the guy.
I presume and hope that only the mosfet are burned, so soon I can have some IRF640, I will replace them.
Thank
Bye
Gaetan
Remove the bad MOSFETs and try to run it. You should be able to measure about 170v on some of the large capacitors inside it.
There are 200V MOSFET with much lower Rds-on and similar gate charge, like IRFB4227, that could make the inverter far more rugged.
Not trying to thread jack but...
I had one of these units a couple of years ago. It was connected to a marine deep cycle and I used it as a "generator" for places without power at work. Unfortunately, some upstanding citizen stole it from me. I miss it.
Is it feasible to build a comparable unit for less than the $300 they cost here?
I had one of these units a couple of years ago. It was connected to a marine deep cycle and I used it as a "generator" for places without power at work. Unfortunately, some upstanding citizen stole it from me. I miss it.
Is it feasible to build a comparable unit for less than the $300 they cost here?
Yes. But it takes experience to make one that works reliably.
One of my friends is doing something similar. Just not exactly to save money - he's making a DC/DC converter that accepts 24v from a hybrid bike and outputs 340v to run various electronics. Although it probably would in fact cost less than a 12v inverter of the same wattage rating. (He's using transformers out of old PC power supplies, apparently without any modifications.)
One of my friends is doing something similar. Just not exactly to save money - he's making a DC/DC converter that accepts 24v from a hybrid bike and outputs 340v to run various electronics. Although it probably would in fact cost less than a 12v inverter of the same wattage rating. (He's using transformers out of old PC power supplies, apparently without any modifications.)
star882 said:
That's where you folks come in. 😀
I'm not necessarily looking for cheaper. I have some parts and meager skills to draw upon and would be doing it for the same reason I do any of the things I do - I like it.
MJL21193 said:
Hello
Here is a link to a modified sine 2500watt inverter.
http://www.diyaudio.com/forums/showthread.php?postid=1168405#post1168405
It seem to be not too difficult to made.
Bye
Gaetan
This inverter looks like the one I have repaired some time back, please for economic point, remove all o/p transistors, power the system; if you have a c.r.o,test for pulses to the gates of irf 640. probably you should be in a position to get rectangular pulses of magnitude greater than 4volts and 7.5volts and same should apply when using a digital multimeter.
If not available then try to replace the pwm ic and even the quad NAND gate till you all the gates give the o/p that is symetrical.
If not available then try to replace the pwm ic and even the quad NAND gate till you all the gates give the o/p that is symetrical.
MJL21193 said:
Keep looking on ebay often. xantrex sells a lot of 'B' stock units to and through various dealers.
I managed to pickup a brand new 3000 watt xantrex unit for $100. The same one that is at Canadian Tire and labeled as a 'MotoMaster' unit. They have it for $499 ($599?). I like $100 -- much better.
Every now and then you can grab a prosine unit, maybe one of the 2kw or 3kw -true sine- units for a few hundred$, as the owners have no idea what they have in their hands-- or if it even works.
I saw a prosine 2.5 (2500watt continuous, 5kw peak draw) true sine unit like that go for $248US a few months back. You should be able to find what you want if you search smartly..and take about a week to do some 'fishing'. The prosine units originally sold for over $2,000US. The Prosine units are nice as they have auto-switch and auto battery charge in some models. They are older models..but with some new caps (if one feels it is necessary) they could last another 10 years, easy.
I think one is better off buying one of these units in 'unknown' condition off of fleabay and then fixing if necessary, rather than engineering a modified sine unit that has not much in the way of refinement vs that of the Prosine units.
Yep. I just checked on flebay, in past auctions. A Prosine 1800 (true sine and 2x surge headroom) just sold for $200.
Yah just have to be patient and wait for the right prey to walk by.....
Edit: a Prosine 2500 (5000 surge) JUST sold for $135! that's a $2500 unit. holy7 smokes!! (autoswitch, charger and everything on that puppy!)
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