Rewinding a shorted SMPS transformer
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From: Jim Flanagan on 17 Feb 2010 17:24 I have a defective SMPS transformer which I cannot replace and am contemplating rewinding the primary which has shorted internally. I've rewound 60Hz power transformers in the past with no problems. What are some pitfalls that I might run into when attempting this. Any help is appreciated. Thanks Jim
From: Tim Williams on 17 Feb 2010 17:32 "Jim Flanagan" <jflan(a)tampabay.rr.com> wrote in message news:4b7c6cae$0$4979$9a6e19ea(a)unlimited.newshosting.com... > I have a defective SMPS transformer which I cannot replace and > am contemplating rewinding the primary which has shorted > internally. I've rewound 60Hz power transformers in the past with > no problems. What are some pitfalls that I might run into when > attempting this. Not much problem with it, I do it simply as another part of prototyping. http://webpages.charter.net/dawill/Images/RegBO1.jpg Since you've already made transformers, I don't really have anything else to say. Insulation, wire size, all that stuff applies the same. Just avoid big fat wire, since it gathers eddy currents just the same as non-laminated iron does at LF. Multistrand and litz are wonderful things. As far as taking things apart, use heat to soften up the varnish. Even so, cracks are common, which is why I say this: "Superglue is an integral part of disassembling ferrite cores." Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
From: D Yuniskis on 17 Feb 2010 17:44 Jim Flanagan wrote: > I have a defective SMPS transformer which I cannot replace and > am contemplating rewinding the primary which has shorted > internally. I've rewound 60Hz power transformers in the past with > no problems. What are some pitfalls that I might run into when > attempting this. Are the "coils" physically separate? Do you know if they were wound bifilar? Ferrites are more brittle than the iron cores you are used to with "60Hz power transformers"...
From: Robert Baer on 17 Feb 2010 22:38 Jim Flanagan wrote: > I have a defective SMPS transformer which I cannot replace and > am contemplating rewinding the primary which has shorted > internally. I've rewound 60Hz power transformers in the past with > no problems. What are some pitfalls that I might run into when > attempting this. > > Any help is appreciated. > Thanks > Jim Just like one might do with power transformers: count the turns as you take them off, measure wire size and replace. Pitfalls: getting the damn thing apart without breaking - since it is that critical you will discover that no solvent in the world (save H2O which will dissolve everything) will get that damn lacquer / paint / epoxy off because it is all three and more insoluble than the core itself. Been there.
From: Robert Baer on 17 Feb 2010 22:39
D Yuniskis wrote: > Jim Flanagan wrote: >> I have a defective SMPS transformer which I cannot replace and >> am contemplating rewinding the primary which has shorted >> internally. I've rewound 60Hz power transformers in the past with >> no problems. What are some pitfalls that I might run into when >> attempting this. > > Are the "coils" physically separate? Do you know if they were > wound bifilar? Ferrites are more brittle than the iron cores > you are used to with "60Hz power transformers"... yeah...a LOT more brittle. |