Whats the best way to remove a circuit encased in resin

[jpoopdog]

I have a bunch of these kinds of ignitors https://www.sparkfun.com/products/retired/11218

not literally those, but probably made with the same parts, same manufacturer, and so fourth.

today i realized 4 i bought were dead. they work but only produce some 1kv or so, the input however is about the same.

It happens allot, a huge flaw in these things is that the input wires usually have resin on them which, either chemically, mechanically, or both, brittles them making them fall off right at the base, so difficult to resolder on. Also, they overheat and fry quite quickly due to the incredibly poor heat conductivity.

What i want to do, is get the circuit out of that resin, so i can replace the transistor, or just extract the transformer at least which is all i need to build my own setup for one that runs constantly, for producing ozone which these things are apparently capable of doing.

Also i want to see what it all looks like in there too. i understand of course that without an insulator it would be impossible to use these transformers in open air.


So, what do i do to get the resin away?
Understand im not doing this explicitly for making ozone, or anything i should be advised to just "go and buy it", if thats your recomendation, or anything other than an honest answer or advice for extracting the circuitry, then lets pretend that this is a scenario in which it is impossible. I spent allot of time playing with these and reselling them too, im genuinely curious about the inner workings.

One more thing to clarify, this resin is most likely there to stop the transformer inside shorting on itself or damaging the other components, its high voltage insulative resin, if anyone knows what its composed of and how to get rid of it.

At very least i want to be able to extract the transformer and look at the oscillator, though i think its likely just a simple flyback setup modulated like disposeable cameras are, with a center coil for measuring flux or something i cant remember.

 

[jpanhalt]

These questions are not infrequent, and they always come down to finding out what the resin is. Is it hot melt, epoxy, RTV silicone, polyester, acrylic, a mixture or inorganic+binder, and so forth.

Can you describe the potting compound? Have you tired any solvents on it? Heat? Is it brittle? Rubbery? What color? If you burn a chip, what does it smell like?

Bottom line for most of these inquiries is physically removing the potting with a chisel and/or grinder.

John

 

[Colin]

I use paint remover.

 

[dr pepper]

To be honest it probably isnt worth the effort, I've unpotted the odd circuit, you can buy expensive chemic for doing it, or as I found on one item you can use a hot air gun and a craft knife to peel the mank off, this will only work on certain compounds.

 

[tomizett]

Heat and scraping is certainly worth a try, given how cheap and easy it is. As Dr Pepper says, it works quite well with certain compounds, even ones that seem quite hard and brittle at room temperature.

 

[ronsimpson]

You are planning on re-potting the thing I hope. It will not work sitting in air. (maybe)

 

[Mikebits]

You are planning on re-potting the thing I hope. It will not work sitting in air. (maybe)

You think it will zip-zap, and snap, crackle, pop?

 

[ronsimpson]

We used to make flyback transformers (7 to 30kV depending on size). Potting is one of the secrets to keeping them working for years. We had to pot them in a vacuum to get the air bubbles out of the compound.

 

[jpoopdog]

It would honestly be enough for me to just find the transformer inputs, snap the rest off and leave as is, control it myself.

I hadnt thought about heating the thing to like 200 degrees then trying to pick it apart, i just asumed i would have to melt it away. Thats a good idea if it breaks away differently under heat

 

[dr pepper]

At the risk of sounding a smart pants let me just say if you get a ferrite core transformer hot enough to melt solder you have probably exceeded its curie point and massively changed its specs, resulting in a bang when you apply power again.
Be carefull with the heat.