Removing potting compound to allow repair

[perdrix]

I've got a chinesium DC-DC converter 12V to 18V 8A.

It's one of these: https://www.ebay.co.uk/itm/165145242820 and is potted with a very solid black potting compound.

This the second replacement that I've purchased because the originals failed (after > 1year).

Next time if it fails I would like to try to repair, but removing the potting is problematic.

Any suggestions on how to remove the potting compound without damaging what's inside...

Thanks
David

[cybermaus]

On another post, someone suggested soaking in acetone rather then IPA
I have not tried it myself though.

Also, if you already have two broken ones, why wait for the 3rd one to fail. Open one preemptively.

Though of course the suggestion of chemicals into the environments is a valid one.
What is more circular: Using chemicals to fix one, or allow the Chinese to waste resources to build yet another one?

[jonpaul]

Chinese wall PSU are the cheapest , poor specs, bad reliability 


Surprised they last a year.

Depotting is difficult, may be hazardous and the units are not useable afterwards.

Suggest to buy a quality PSU from a supplier with a warranty and support and no0t Chinese junk

Jon

[PartialDischarge]

Basically there are 2 that could help: gasoline or butanone aka mek.

[ESTechnical]

Hi,

We have had some success with removing potting with paint strippers that contain dichloromethane or methyl ethyl ketone. Try Paint Panther or Power Strip. Also, silicone remover gel contains MEK, so that might work too.

Be aware that this will also strip soft PVC cable insulation, the epoxy coating of some capacitors etc. Most SMT parts survive completely unscathed but dipped capacitors will probably turn gooey!

An ultrasound cleaner and acetone (outside!) may also help clean it up.

Good luck!

[Martin Miranda]

heat it with a hot air station. then dig out the epoxy potting. it's slow but just options to skin a cat. 

[perdrix]

Suggest to buy a quality PSU from a supplier with a warranty and support and no0t Chinese junk

Jon

Well if I could find a good one with that specification ... Pointers gratefully accepted.

[ESTechnical]

https://www.ebay.co.uk/itm/174696916905

Is this more suitable? Certainly an easier task to fix if it breaks haha

[cybermaus]

Personally, I really rather have a potted and encased one if I were to mount it in my vehicle

Though one that does not break, so the 20 Amps may be a good idea.
Which reminds me: You are giving the 8Amp one proper cooling? Its not like you buy one with integrated heat sink, and then stuff it between the padding of two seats without air or metal? If you run them hot they will indeed no last long. Solid connection to metal on one side, open air on the other.

[perdrix]

In real use for my application the current draw is below 1A most of the time with very occasional peaks of up to 5A for short durations, so 8A rating seems reasonable.

The module always ran cool.

D.

[abdulbadii]

Do hot air gun at least 153 ^oC and immediately slowly chipping away the glassed compound. It'd be time consuming true, Imho no way else