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DE-potting a transformer

:: EPE Chat Zone ­:: ­Radio Bygones Message Board :: » EPE Forum Archives 2007-2009 » Archive through 13 August, 2008 » DE-potting a transformer « Previous Next »

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steerpike
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Username: steerpike

Post Number: 374
Registered: 05-2005


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Posted on Tuesday, 08 July, 2008 - 06:53 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hi all
Does anyone know of a solvent that will soften that transparent resin (I suspect it's polyester resin) that they cast transformers in?

(I need to remove a transformer from its potting box, because it's burned out, but the specially molded potting box forms an integral part of the chassis, and so the new transformer needs to go inside it.)
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neroku
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Username: neroku

Post Number: 35
Registered: 09-2007


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Posted on Tuesday, 08 July, 2008 - 09:26 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Perhaps boiling water will do.
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obiwan
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Post Number: 2304
Registered: 12-2005

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Posted on Wednesday, 09 July, 2008 - 01:34 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Heat will often soften it up. But I think you're out of luck really. If it's what I'm thinking you're talking about, it's just a matter of chipping it away. Even then you may not have much left of it.

You can sometimes soak it for a LONG TIME in solvents like acetone or something and that will soften it up. But it takes days or weeks to do so.
Do Not Hit The Fly That Lands On The Tigers Head.
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atferrari
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Post Number: 594
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Posted on Wednesday, 09 July, 2008 - 04:06 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

I recall Don Lancaster talking about that, many many times. He always said it was possible with the right chemicals. But I cannot recall if he ever mentioned them.

Give a try in his site: "tinaja" something, I think it was.
Agustín Tomás - Buenos Aires - Argentina
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zeitghost
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Post Number: 1182
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Posted on Wednesday, 09 July, 2008 - 08:49 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Boiling concentrated sulphuric acid is used in the semiconductor industry for removing epoxy packaging... however, I wouldn't recommend it for continued good health in the absence of a fume cupboard... and it'll eat your transformer anyway.

One of my colleagues used a heat gun to hack his way into a potted circuit once, but it was hard work.
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terrym
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Post Number: 617
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Posted on Wednesday, 09 July, 2008 - 09:30 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Checking Don Lancaster's site, he doesn't give any specific solvents I could find. He does say however, that the companies that make the potting compounds also sell striping solutions. Maybe try some of those companies and see what they have.

TM
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sounded_simple
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Username: sounded_simple

Post Number: 338
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Posted on Wednesday, 09 July, 2008 - 11:36 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

I found that IPA worked on some compounds.
Its very slow and still messy at the end.

Id be more inclined to look at other options.
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ecotec
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Username: ecotec

Post Number: 5
Registered: 09-2007

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Posted on Wednesday, 09 July, 2008 - 12:12 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hi Steerpike,

I used to do this a lot many years ago.......Usually I was trying to find out why something potted had failed.

You could try this:

http://www.dynaloy.com/Products/tech_data_sheets/Dynasolve%20185%20PDF.pdf

It may be similar to the liquid I used.

Don't do this indoors!
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steerpike
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Username: steerpike

Post Number: 375
Registered: 05-2005


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Posted on Wednesday, 09 July, 2008 - 02:17 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

I phoned the fibreglass dealers here ; they said dimethyl chloride should do it; so I just have to get hold of some & see.
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g6osv
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Post Number: 51
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Posted on Wednesday, 09 July, 2008 - 04:05 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Have you tried paint stripper that usually comtains dimethyl chloride.
Ian
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stylers
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Username: stylers

Post Number: 125
Registered: 04-2005

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Posted on Wednesday, 09 July, 2008 - 05:24 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

acetone usually softens the stuff up a fair bit, but you still have to chip away at it, soak again, chip away, soak again etc..
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ant
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Username: ant

Post Number: 310
Registered: 05-2006

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Posted on Wednesday, 09 July, 2008 - 10:06 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hello all,

There is a way but it's drastic - drill it out. Carefully! A pillar drill would give far more control, obviously, than a hand-held drill.

It may be possible, perhaps, to drill down alongside the transformer to give the chemicals a greater area to attack, if they're working at all.

Regards Ant
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grab
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Username: grab

Post Number: 768
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Posted on Tuesday, 15 July, 2008 - 11:22 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

IPA might work, but perhaps stout would do better - lager probably doesn't have enough of anything to do much. ;-)

Oh, not that kind of IPA, you say...?
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steerpike
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Username: steerpike

Post Number: 387
Registered: 05-2005


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Posted on Friday, 25 July, 2008 - 05:09 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Now I have acquired the Dichromethane (= methylene chloride, apparently its obsolete name).
So experiments this weekend & I'll let you know.
Unless I asphyxiate myself - rumour has it, it's quite poisonous stuff. Maybe I should save some, there are a few politicians I think deserve a dose.

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