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ifrythings 21st July 2006 09:45 PM

How to dismantle transformer?
 
I'm trying to dismantle a transformer out of a PC Power supply, I read a post made my N-Channel stating to bake the xfmr at 350-400F for 30-40 minutes.

Now does this cause all the lacker to drip out of the xfmr or just softens it up?

Does this work on all xfmr's?

thanks

Dave

carvinguy 21st July 2006 10:19 PM

Dave,

When I take apart transformers, I use a heat gun and try to uniformly heat the entire transformer by moving the gun all around it until the potting stuff begins to soften. Then I carefully pull the core out of the bobbin. Whatever the stuff is (These have been xfmrs from China- I don't think it's laquer, but who knows??), it never liquifies, just softens enough to get things apart. I usually then let everything cool and scrape off as much of the potting material I can with a razor blade so it will go back together easily without interference.

I can't say if this would work on a properly potted xfmr- usually, most cheap SMPS xfmrs are just dipped in the stuff and not vacuum potted.

I'm sure heating it in the oven would work great, but I don't have access to one in my workspace. In fact, the oven would work better on larger transformers. I've only needed to dismantle xfmrs no larger than ETD-49 with the heat gun.

Matt.

lndm 22nd July 2006 12:47 AM

I would have to say it depends on the lacquer. Some (probably older types) laminations will break apart nicely (will snap and leave flakes) but should be cool for this to work best.

sawreyrw 22nd July 2006 01:08 AM

Is this really worth the trouble and potential health risk? Who knows what's in those transformers, if they are made in China? Finally, if you don't know what the core is, how can it be useful.

ifrythings 22nd July 2006 01:18 AM

hmmmm.... Oven trick didn't seem to work. I put it in there at 400F for 40 minutes, pulled it out and tried pulling the pieces apart with no luck :( .

Quote:

Finally, if you don't know what the core is, how can it be useful.
What I'm tring to do is take apart the xfmr, remove the secondary, then I want to wind a new 13.6V secondary on it. Then I have a cheap 13.6v 20A power supply thats efficent and small.

infinia 22nd July 2006 01:24 AM

ifrythings
 
Not limited to frying but even baking things now;)

ifrythings 22nd July 2006 02:44 AM

Re: ifrythings
 
Quote:

Originally posted by infinia
Not limited to frying but even baking things now;)
Indeed, now only if I can get something out of baking these then I'll be happy.:D

N-Channel 22nd July 2006 05:43 AM

Quote:

Is this really worth the trouble and potential health risk? Who knows what's in those transformers, if they are made in China? Finally, if you don't know what the core is, how can it be useful.
Most of the time, the core material is similar to the #77 or "J" ferrite material. No sense in having a wide variety of core materials if all they do is the same thing: switch large amounts of PWM Power at 33-36kHz.

I have to agree with carvinguy. While baking them for 30-40min @400F might work, using a good heat gun is that much better. Faster, too. I'm suprised I didn't think of that in my other post. :rolleyes:

Steve

infinia 22nd July 2006 06:08 AM

I used to specify for the factory to clean and then locktite (superglue) ferrite halfs together. Best bet is get ahold of a new core then crack open the old.

johnthedoctor 22nd July 2006 06:41 AM

I've looked but can't find it now, a few hours ago was reading posts re. smps supplies and it was Carlos (I think) that was talking about adding a resistor in series with the 5v zener from a pc psu. End result was 13.8v from what was the 5v rail and plenty of current.

Seems like a lot less work than rewinding the tranny. Also, some have a pot to alter the 12v rail, you just might find one of those.


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