How to dismantle transformer?

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ifrythings

ifrythings

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Joined 2005
#1
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
 
#2
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.
 
#5
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 🙁 .

Finally, if you don't know what the core is, how can it be useful.
Click to expand...

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.
 
#8
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.
Click to expand...

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. 🙄

Steve
 
#10
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.
 
#14
Methods of removing it is to dip the whole tranny into thinner. The thinner will dilute the varnish making it easier to work with.

Also another way to liquidfy your varnish is to bake the trannies to 180-200C. At this temperature varnish will start to liquidfy and will start to flow out of the trannies(position them in a way the varnish can flow).
Also use some form of vibration while trying to remove the core will help.
I use this method when trying to remove trannies for rewind at our tranny workshop
Hope this helps
Nicholas
 
#15
If your core is a laminated type what has always worked for me is a stove element. Put in on there sometimes with a lid overtop works fine. I think boiling or water in general will corrode or damage the material. Getting the first E is the hardest and may be damaged, while its warm you can usually break or pry apart sections in no particular order. Re heat and repeat until its done. I've never wrecked the plastic bobbin either.
 
#16
ocool_15 said:
If your core is a laminated type what has always worked for me is a stove element. Put in on there sometimes with a lid overtop works fine. I think boiling or water in general will corrode or damage the material. Getting the first E is the hardest and may be damaged, while its warm you can usually break or pry apart sections in no particular order. Re heat and repeat until its done. I've never wrecked the plastic bobbin either.
Click to expand...


Heat gun on it for a few minutes and all the laminations fall out (with a small touch of the finger of course 😀 )

The transformers I'm dismanteling are ferrite. (But thanks for the suggestion for Laminated ones).

The heat gun works on the ferrite ones, but I got two apart and 3 cracked in the heating process 🙁 :bawling:
 
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