Roomba CHM (Brush Deck) Motor “Repair”

Just a quick post, but the other day, my Roomba proceeded to suck up a baby wipe (that my son had apparently left somewhere randomly and I didn’t see while picking up the main floor before bed), and the brushes jammed up enough that it didn’t trigger the “clean brush” warning, but probably overheated the Cleaning Head Module (CHM) motor (see picture). After removal, the brushes refused to run. Spinning the brushes manually was easy, so it wasn’t physically seized. Unfortunately, replacing the motor (eBay) is basically the same price as buying a whole new CHM. Checking the electrical resistance on the motor was about 8ohms. Not too bad, but, I’ve never cleaned the motor, so I gave it a few good squirts of DeoxIT, and spun it a while. Checked the resistance again, and it was 22k ohms. Huh. Hooked it up to my bench PSU at 9V, and powered it up. Nothing. Crap.

So, I gave it another spray of DeoxIt, spun it a few more times, and let it sit for a few minutes (let the solvent evaporate). Now it read 2 ohms. Cool. Powered it up, and it spun very well. Ramped the voltage up to 12V and it was drawing 160mA. Cool. Let it run for a few minutes, and put the CHM back together. Tested again, and it worked.

Reinstalled in Roomba and let it run. The CHM worked great for about 30 minutes, then stopped again. Removed the dust pin, and saw it wasn’t spinning (actually, it would start to spin then stop). Spinning the brushes by hand wouldn’t get them going either. =/ Crap crap. Figuring I had nothing left to lose, I gave it another DeoxIT spray, and then blew it out real well with my air compressor. Quite a bit of DeoxIT blew out of the motor, and all of it very black. Hmmm… I kept blowing it out until nothing else would blow out (I probably could keep spraying it out too, but no sense in doing that). Plugged it back into the Roomba, and the brushes fired right up. Huh. Let the unit run for 2 hours (told it to Dock, then unplugged the Dock), and the Brushes ran the whole time. Also ran for however long it’s normal 1am cleaning cycle is. So, must have just been dust/grime. So, I guess one more thing to add to the maintenance of the Roomba is a good compressed air cleaning of the CHM motor. Though maybe the Aerovac upgrade will help with this in general since it actually sucks air through the CHM.