Reviving an aged A*32u4 Micro...for reals

I think I need a recommendation on how to revive an old 32u4micro. Like dropping it in a ultrasonic cleaner or something…can they be?

These are great little boards, and have been in constant use…outdoors. Currently have two deployed. So, there is a bit of corrosion around the usb connector. Frequently they do not show in Device Manager. However, I can still somehow upload new code to them. Maybe it requires a double tap on RST to get the ports switched over for upload. Sometimes not. There is no real consistent symptom I can nail down.

Re-installed Pololu 32u4 board drivers and the likes, tried a variety of cables, and then I found a couple boards still sealed in pink. Plugged them in and no problem, there’s the BLINK. Hehehe.

So, I think there’s fouling in the USB connector on the board. What methods of cleaning will these boards tolerate? Soaking in soapy water? Some other household cleaner? Other suggestions?

I don’t really have an ultrasonic cleaner, but kinda wish I had if this is recommended.

Thank you for taking an interest in this topic.

Hello, Mark.

Using an ultrasonic cleaner seems like a good way to clean electronics like these, but we do not have any direct experience with them. If you go that route, it will be especially important to ensure your parts completely dry before you try and use them again, and because of the risk of corrosion and damage from remaining liquid, we generally recommend against other cleaning strategies that involve completely immersing boards.

Alternatively, some manual effort combined with compressed air and isopropyl alcohol (applied carefully using cotton swabs or lint-free cloths) can go a long way. There is a lot more useful advice available on the internet than is practical to cover in one post, so here are a few quick results I found that all seem to have good recommendations:

For future projects where you plan on using electronics outdoors (or in other less than ideal environments), you might consider applying a conformal coating to help protect it from the elements.

By the way, if the USB connectors are no longer reliable on your A-Stars, or if they are consistently the first failure point in your application, and you want to continue using them, you might consider using an AVR programmer to program the board through its ISP headers.

Also, just out of curiosity, can you tell us how long your A-stars were operating outdoors for before you started noticing issues? What kind of environment have they been exposed to?

- Patrick

Hey Patrick, thank you so much! Yikes, I should have done my own research first. Other than thinking scrubbing the USB ports with alcohol, maybe the rest of the board too. Lint free is the trick as that’s prolly what clogging the port up. Get plenty small paintbrushes around here.

There’s my excuse for getting some drying N2.

Typically wired up the SPI, for use with nRF24 transceivers, and those pins are off 0.1" layout. I just go for what is convenient for me. No complaint.

In a tropical environment, typically sealed having thru-hulls of cable glands or RTVd, since 2014. Again, no complaint. Have a reason here for going to 328PB Micros, rotating some gear, retiring some. Am in the southern lee of Pololu Valley, so wet, yeah, wet.

Kinda psyched now, can make this a decennial board swap out.

Thanks again Patrick! Will review the links you provided. Will post up with positive progress. I get about ten of these going look at. Shoots, why I like this particular board is because it has a wide operating voltage range so can directly supply from a 12V PV charge controller.

A hui hou!


That’s great! I am glad to hear it’s been working well for you all that time. It’s pretty dry here on the 9th island, so we don’t get many opportunities to test how well our products work in high humidity settings. It’s nice to get that point of reference!

By the way, if you feel like sharing, there are several people here who’d love to see pictures of your gear in action.

- Patrick