I’ve written previously about the iRobot Roomba automatic vacuum cleaner that I bought in November 2006. I’ve had it replaced once (broken speaker) and repaired once (dead battery) within its two year warranty.

Recently the Roomba stopped working again. Yesterday I did some diagnostics and it turned out that the right outer cliff sensor wasn’t working properly. The infra-red detector was working (it reacted to the beam from a virtual wall), but the emitter wasn’t… emitting. I could tell by looking through my digital camera, which picks up infra-red light.

IR diodes

I didn’t want to buy a new Roomba, since they’re quite expensive. And the problem annoyed me since I don’t even need a cliff sensor. I live in a one floor apartment.

The warranty period had passed last year, so I took out a screwdriver and opened up the front bumper. There I could disassemble the cliff sensor. At first I thought that I could short the circuit and make it work that way, but it didn’t seem to work. What I ended up doing was to take apart both the outer cliff sensors (the front ones had some glue or whatever on them) and tie together the left emitter with both the left and right detector, making the Roomba think that its sides are on the floor all the time.

And voilĂ ! It runs like a charm again!

Fixed Roomba

It’s not very elegant, but it was easy to do. I hardly know anything about electronics, so I’m very proud of myself right now :lol:

One thing I noticed though, is that the Roomba is far noisier on wooden floors than on plastic carpet like I had in my old apartment.