A few weeks ago my iRobot Roomba started spinning in circles and failing with a 9-beep error. This error is related to the two bumper sensors located at 10 and 2 o’clock. In some cases there might simply be debris behind the bumper interfering with the sensors. I ruled this out with a disassembly and clean.
If your unit is under warranty you would likely be sent a replacement unit for this case, but that being said, mine was not. Plus I was secretly looking forward to a full disassembly.
I followed a combination of instructions I found on the net to diagnose and replace the faulty part.
The problem is caused by one or two faulty “Bumper Articulating Arm Optical Sensors” in your robot. These sensors consist of a plastic arm that swings between two IR sensors. My readings on the working sensor showed a range of 0-5 volts.
The first sensor I tested functioned correctly switching between 0 and 5 volts. The second sensor was fixed at 0v. I had read about shorting out the IR to half blind your Roomba but I was not in the mood to solder fragile wires. With that said, I managed to find a replacement part from Protech Robots.
A week and a bit later (the item was shipped USPS ground) my part arrived and it was time to put Roomba back together again.
Here comes the trickiest of the parts. You need to follow all of the wires from the sensors to the connector located in the bottom right of this photo, ignoring the white wire that connects the two sensors together. Carefully remove any material securing the cables together. I highly suggest you draw a visual of the connector and keep track of the individual wires as you remove them. To remove the individual wires from the connector you need to gently lift up the plastic the secures the wire, and pull at the same time. I used a small paper clip to lift the plastic.
Once the connector is reassembled the rest of the steps are just the re-assembly of the robot and testing.