Cleaning PCB Soldering Residue

The lovely clear plastic Shruthi-1 enclosure has made me self-conscious about the state of the back of my SMR-4 circuit board, since it will potentially be visible. There is whitish residue from soldering all over it. Anyone know of a good method/substance to remove this?


It might depend on the flux in your solder. I tried some Servisol flux remover and it worked to some extent - it did not really remove the flux, it sort of spread it all over the PCB and turned it into a greasy mess.

Ah, it’s the flux from the solder- was wondering what it was. I have some isopropyl alcohol I bought years ago to clean tape heads. I may try that.

Thanks for the tip.


Pretty sure alcohol turns to water after a couple of years. I know peroxide does. Either way it should work. I just pop the stuff off with my thumbnail.

I wouldn’t be so worried if it weren’t for the transparent case. Maybe the solution is to get a non-transparent case…


nobody sees it on the bottom side . . . . but i can make a black bottom panel for you :wink:

I’D see it…
I was actually thinking of spraying the inside of the case with white paint. Thought that might look nice, as you’d be able to see through the thickness of the acrylic to the opaque paint layer below. I’d want to have a spare case to experiment on though, and the Mutable Instruments shop seems to have sold out of them again (that didn’t take long…).


the good thing in having a spare case is that it can be filled later!

That’s true. If I’m convinced that the other filter boards sound significantly different to the SMR-4, I’d be tempted to make up some more with different filters. I might make one of the IR3109 ones anyway, as I had an SH-101 for a while, and really loved the filter on that. I’ve also noticed some talk on the forum about a possible future MS-20 clone filter. I’d definitely be interested in that, should it materialise.


I too got a very sticky, greasy mess when trying to remove the flux residue. I found that several applications of a solvent with the use of an old toothbrush in between applications, along with holding the board in a vertical position allowing the solvent to run off, helped a lot.

+1 for MS-20 filter clone :slight_smile:

I just use organic based flux that rinses off with water.