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I may have to try this on my busted Roomba

April 18, 2007 on 2:50 pm | In Needs more info |

My roomba lost a fight with a protest my cat made in the corner. The roomba now only goes backwards. I may have to try this fix for the roomba circle dance.

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So it worked.

Had to google for some how-to on dismantling a Roomba (and couldn’t find one for the plain Roomba Discovery that I have). After the obvious task of removing all the visible screws on the bottom of the main body, the ones holding the front bumper skirt on, and two deeper in the wheel wells, it’s pretty straight forward.

Pop the front skirt off (it’s friction fit held in place by the screw posts from the screws and two clips on the edges), unseat the IR sensor cable, and set it aside. After that, pop off the top, unseat the buttons cable, and set that aside. You’re left with a topless roomba and the task of getting the wheel covers off so that you can get at the tachometer IR diode and IR sensor in the wheels. Here’s the problem. One of the screws isn’t reachable on some models because of the exterior “fender” portion of the body. Some newer roombas have a removable fender, some don’t. Some howtos suggest drilling a hole but I found it just as easy to remove the wheel. From the bottom of the roomba the bottoms of two screws are visible next to each wheel. The heads are at the top, under the lid. You have to remove these two screws at which point a plastic block holding the wheel assembly into the base will fall out. Once both of these blocks are removed you can push the wheel up out of the wheel well and get at the fourth wheel cover screw. Remove the wheel cover (carefully note how the wires route along the wheel cover edge - this is important as they’ll rub against the drive belt if they’re out of position), remove the drive belt, and remove the spoked wheel. It is on a plastic axle that rests inside a planetary ring gear assembly inside the wheel. Near as I can tell these are all trapped gears so you don’t have to worry about anything inside the wheel slipping out of position when you remove the tachometer gear. Clean the two translucent probes (one’s an emitter, the other’s a sensor - same as in a mechanical ball mouse) and reassemble.

After running through this, my busted roomba drives straight. Now all I need is to replace the brushes that were destroyed in the fight with the cat dropping and get a new battery (the original has since worn out in the new roomba and the new roomba has its original battery). Or perhaps just rebuild the old battery.

Comment by suboptimal — May 19, 2007 #
Six screws on the bottom, at the back, three on either side of the dust bin:

Two screws, one on either side of the battery bay - battery removal required:

One screw on each side, just forward of the wheel mount

Bumper screws - 1 of 4

Bumper screws - 2 of 4

Bumper screws - 3 of 4

Bumper screws - 4 of 4

After all four bumper screws are removed, flex the gray bumper skin until the catch on the bumper skin comes off of the black under structure and lift the bumper. Keep it close to the body of the Roomba as there is one wire bundle connection to the base that can be disconnected after the bumper is lifted.

Two screws, one either side, in the depth of the brush carriage on the forward edge.

Lift the white body skin, again not too far as there is a wire assembly connected to the base

Two screws for each wheel mount

Four screws on each wheel cover. As you remove the cover take careful notice of where the wiring is routed between the structure of the wheel and the edge of the wheel cover.

With the wheel cover removed, remove the drive belt and pull out the tachometer pinwheel

And now the goal - the exposed tachometer IR emitter

Debris will get caught here and disrupt the tachometer IR sensor’s read of the IR emitter signal through the tachometer pinwheel

Clear the debris, put the pinwheel back, put the drive belt back, put the cover back on the wheel being careful to route the wires around the outside of the guard that keeps the wires from being destroyed by the drive belt, rotate it back into position with the wheel mounts, then put the skins back on and reseat all the screws.

Comment by suboptimal — August 18, 2008 #

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