inverter repair

attempting to repair 3 identical inverters, anyone with mosfet know how please chime in, samwin sw640 mosfet,trying to do this cheap,trial and error,so do i have to use that mosfet or is their another one that will work,i can buy ten on amazon for 23$ 69$ for three inverters,1000w modified inverter,hope you can help

most all mosfets take the same trigger volts/amps, the main difference is in the max current/volt rating
thru the collector -emitter and of course the mounting style.
the problem with cheap mosfets is well... their cheep! un trustworthy etc

jjww said:

most all mosfets take the same trigger volts/amps, the main difference is in the max current/volt rating
thru the collector -emitter and of course the mounting style

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can you recomend a replacement,some are really cheap

this one i cant find

fire hazard said:

this one i cant find

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The trademark is Alpha & Omega Semiconductor, aosmd.com.



Send the picture to them for identification. Full part numbers are rarely printed on the parts these days.

My brief search suggests it is an AOT400, datasheet attached. That part is obsolete, though these folks have some surplus stock:


Be aware that MOSFET failures are very rarely the MOSFET itself. Something else in the circuit can cause MOSFETs to fail. Also, when a MOSFET fails, it usually fails shorted and often sends damaging voltage out its gate pin which blows up the MOSFET driver. Fixing these sorts of things can be a frustrating exercise where you find a blown MOSFET, think that's the problem, replace it, and it goes poof on power up due to other faults.

Mike C.

mciholas said:

The trademark is Alpha & Omega Semiconductor, aosmd.com.

View attachment 215552

Send the picture to them for identification. Full part numbers are rarely printed on the parts these days.

My brief search suggests it is an AOT400, datasheet attached. That part is obsolete, though these folks have some surplus stock:

Electronic Component Distributor | Quest Components

Electronic components distributor with large in stock inventory. Over 130 manufacturers with electronic components added daily. In stock items ship same day.

www.questcomp.com

Be aware that MOSFET failures are very rarely the MOSFET itself. Something else in the circuit can cause MOSFETs to fail. Also, when a MOSFET fails, it usually fails shorted and often sends damaging voltage out its gate pin which blows up the MOSFET driver. Fixing these sorts of things can be a frustrating exercise where you find a blown MOSFET, think that's the problem, replace it, and it goes poof on power up due to other faults.

Mike C.

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yep, like a dog chasing its tail if you don't figure out what casued it to pop in the first place, and then change everything damaged up and downstream of the popped mosfet.

I, a true menonite, or possibly Amish, tried to repair an older class a car amplifier one time... blew up more shit on the board first time i fired it up then was damaged to begin with...

it was backfeed from the moes ats that killed three inverters,expensive lesson,ok thanks for the help

pretty sure you need a 500+ volt mosfet for any 220 volt inverter, also need to guess (estimate!) amperage per mosfet soooo..
what is rating of inveerter/ number of mosfets in parallel plus a safety margin
samwin is only 200v the other one listed is only 75v both would fail

yeah thats what is in it 1000w 110v inverter,just thought i could fix it cheaper if at all,turn it on no load it just beeps intermitten

With all mosfet repalement, there is a need to chek components around. As mosfet is damaged it allows current to flow in any direction. It is important to validady keying signals and passive elements around it.
I will recommend googling some videos so the new mosfet life will not be in danger.
I attached a service manual that I was using fixing my inverter (your will be different), check with procedure 2.2.6 as there are steps that allow to validate elements.

wow that manual scared me lol,i have three inverters so extra parts,start checking mosfets tomorrow ,its a long road ahead,time consuming forsure, thanks for the input

profesor79 said:

I attached a service manual that I was using fixing my inverter (your will be different), check with procedure 2.2.6 as there are steps that allow to validate elements.

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That's very surprising to see something as detailed as they have provided. Only thing missing is an actual circuit diagram. Certainly very helpful for anyone working on that particular inverter.

fire hazard said:

wow that manual scared me lol,i have three inverters so extra parts,start checking mosfets tomorrow ,its a long road ahead,time consuming forsure, thanks for the input

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Unless I've missed it, you still haven't said what brand and what model your inverters are. A link to a sales page or spec sheet would be helpful.

If you can get one of them going, you can fix all three. As a full time electronics tech, I wouldn't recommend trying to use a cheaper mosfet until you get one going with the original ones. You may get away with it ... but if you choose one with one spec outside of what's needed ... you may find it won't run or keeps blowing up.

As mentioned above, you likely will need to replace driver ICs and probably gate resistors as well ... but that's not particularly difficult or expensive either. The main risk is that if you don't find and replace all the crook parts before you turn it back on ... your new bits will likely fail as well.

Thats a nice manual. I don't usually use any. I used to buy broken inverters cheap, now everyone thinks they can repair them and the prices have increased. Parts are a real issue because there are so many fakes out there. I test the ones I get for breakdown voltage, gate capacitance and on resistance. Most FET are pretty generic though lately there are more high performance ones.

Surface mount devices are not for the beginner. Boards have so little copper these days.

efficientPV said:

Surface mount devices are not for the beginner. Boards have so little copper these days.

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Especially including PB free soldering on large surfaces near mosfets. Most "home" soldering unitcs can't deal with it.
this guy has a lot interesting videos regarding inverter repair/diagnostics: https://invidious.fdn.fr/watch?v=_-GNPwH83rY