Anybody ever disassembled a laminated core transformer?

Has anybody actually ever done this? Is is necessary to dissolve the varnish or lacquer? And is it possible to put it back together again? Thanks.

jwriter said:

Has anybody actually ever done this?

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Yes, several times.

jwriter said:

And is it possible to put it back together again?

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Yes, and they worked fine.

jwriter said:

Is is necessary to dissolve the varnish or lacquer?

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Now that is a bit more tricky!
If it is a really thick coating of varnish, or the transformer has been "vacuum impregnated" which gets the varnish between the laminations, then you are on your own.
As Dirty Harry said: "A man has got to know his limitations"

JimB

Maybe it would be easier to wind my own. Is there a common source of iron laminations and bobbins to fit?

jwriter said:

Maybe it would be easier to wind my own. Is there a common source of iron laminations and bobbins to fit?

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What's your actual goal? There are transformer houses that will do a custom wind at a cost. There are custom laminations houses like this one that will manufacture lams and assemble them to your specifications but I doubt they would make a single set. That being just a single example.

Ron

Hello jwriter.

Have I dismantled laminated core transformers? - Yes, more times than I can remember. - But I did it when I was a kid: I only wanted the wire, so there was no need to re-assemble anything.

Why not have a look at this page which is intended to teach you how to "roll your own":

https://ludens.cl/Electron/trafos/trafos.html

Ferroxcube make transformer parts:

https://www.ferroxcube.com/

- However, I really do not rate their customer service: A few months ago I had cause to consider seriously winding a transformer myself. I contacted that company in writing and they didn't bother to reply.

Farnell sell coil formers and maybe other parts:

https://uk.farnell.com/jsp/search/b...tt=transformer+cores&Ntx=mode+matchallpartial

Good luck.

Analogue.

Depending on what size of custom transformer you need micro wave oven transformers and HID type lamp ballasts(Mercury Vapor, Metal halide, High Pressure Sodium, and Low Pressure Sodium) are by far the most versatile and easiest to come by cheaply and take apart and put back together with minimal effort.

The HID ballasts come in sizes from around 35 VA to 1500 VA with 100 - 1000 Va being the most common and are usually two or three piece cores held to together by simple welds along the seams that are easily cut with a hacksaw or small cutoff wheel in a grinder. The best part is they can be put back together with nothing more than a thin coating of JB weld between the seams!

Motor rewind shops are a good source of wire. Motor wire has a harsh environment with vibration, heat, dust, and often high humidity and chemical vapors.

As Dirty Harry said: "A man has got to know his laminations"

colin55 said:

As Dirty Harry said: "A man has got to know his laminations"

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I know what you are thinking punk, "Did he put six turns, or only five?"

JimB

tcmtech said:

Depending on what size of custom transformer you need micro wave oven transformers

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MWO transformers are normally welded across the laminations.

JimB said:

If it is a really thick coating of varnish, or the transformer has been "vacuum impregnated" which gets the varnish between the laminations, then you are on your own.
As Dirty Harry said: "A man has got to know his limitations"

JimB

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That varnish is specifically made to resist solvents since finished boards often get sent through a hot vapor flux stripper process. Taking apart finsished transformers is a royal pain and usually the wire is destroyed in the process. I have saved the bobbins and cores and rewound them with new wire.

Analogue Robot said:

Why not have a look at this page which is intended to teach you how to "roll your own":

https://ludens.cl/Electron/trafos/trafos.html

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Thanks for that link, really good stuff. I spent a good bit of time reading his autopsy and subsequent re-engineering of a blown inverter too. That was a great read.

https://ludens.cl/Electron/chinverter/chinverter.html

gabeNC said:

Thanks for that link, really good stuff. I spent a good bit of time reading his autopsy and subsequent re-engineering of a blown inverter too. That was a great read.

https://ludens.cl/Electron/chinverter/chinverter.html

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Hi gabeNC, That guy has a lot of interesting projects on his page, doesn't he: Apparently, he's had some of his designs published in magazines.

Analogue.

I don't have any trouble putting laminations back together. If you want to remove old varnisk soak the laminations for 24 hours in Acetone. Be sure to keep a lid on the container so the acetone does not evaporate away. Pull the laminations out of the acetone wipe them dry they will usually be clean if not soak them longer. The varnish is there to keep the laminations from buzzing and making lots of noise. If you go to a motor rewind shop they have the special fiberglass tape needed to put the transformer together for about $5 per roll. Motor repair shops have wire and other things too. I often use cerial box cardboard in my transformers it saves money. Paint each layer with varnish as you wind it after it is all assembled paint it with varinsh and let it dry 24 hours then bake it in the kitchen oven 150 degrees for 1 hour then 250 for 1 hour. You don't have to bake it that only speeds up the drying varnish down deep inside. It is usually good to put varnish on all the windings because if they vibrate it will rub off the enamel coating then they short out. When I was in high school I had a part time job working at Meisners they made transformers. Anytime a transformer tested bad they threw it in the trash so I took home a lot of transformers. I had a good supply of transformers that was 1967 and I still have a few transformers.