I recently got a little Li-Ion charger that’s based of a SMPSU. It had the nasty habit of whining during charging though (it’s loud and annoying).
I decided to tear it apart and see if I can pot it in some epoxy. Of course best results would be if I could put the whole thing is some sorta vacuum to get rid of any voids and air bubbles. I didn’t have that handy, so I used some slow setting epoxy that’s very fluid.
Here’s the charger disassembled. The topside
And here’s the bottom, I then desoldered the little switching transformer that’s making all the noise.
Here’s that pesky transformer
I then used a little masking tape to form a crude sorta mold, keeping all the epoxy from flowing all over the place. Here I have poured in the epoxy
Here the epoxy has cured and I’ve taken the tape off. Seems to have covered everything.
I then assembled everything and tested the charger out. Glad to say a lot of the whining has been removed. I now need to put my ear up next to the charger to hear a perceptible whine.