Microwave Oven Transformer Rewind

Tonight I finished replacing the secondary windings on a 600 watt microwave transformer. I removed this transformer from a pretty small, newer model microwave that no longer worked.



Microwave transformers step up voltage from 120 volts to voltages in the thousands. This particular one was going up to around 3000 volts. I wanted to rewind this transformer to a low voltage so that I could draw a large number of amps from it.

I removed the old windings by grinding and cutting with various power tools. It was harder than I anticipated because of the way the windings were oriented on the transformer. There is a bracket on the bottom that kept getting in the way so I couldn't really use a hack saw like I wanted. After I cut them on both sides, I used a hammer and chisel to push some of the wires through the openings. I also used the pliers quite a bit to pull some of them out.


I enventually got them all out with out damaging the primary windings and was ready to put new ones on.



For the new windings I used 6 guage stranded wire that I had lying around. This was a lot of work because the openings were pretty small on this transformer. I basically just jammed them in there anyway I could. I used a pliers to try and bend the wires so they would make sharper turns and thus take up less room in the openings. I didn't have too much luck with this however. Since there was only room for two rows of wire, I just kind of pout the first row in and then forced the second row in by brute force. It wasn't easy but I got about 5 turns on.





When I was done I gave it 120 volts on the primary and checked the voltage produced on the secondary. I got a little over 4 volts. I'm not sure if that would be enough to build a welder with, but at least I proved the concept.

Since this transformer is rated for 600 watts, I should be able to pull around 150 amps from it at 4 volts. 600w / 4v = 15a

I'm not sure what I will use this one for yet. I may build a welder with it but it depends on how many more microwaves I get that have 600 watt transformers in them. I think I would need about 4 of them to build a welder.

This morning I sent an ad into the local classifieds paper saying that I am looking for dead microwaves, so we will see what I get.

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