Reassembling my Roomba

My Roomba was acting a little quirky. A simple dusting with compressed air more than likely would've sufficed but I was curious.

Digging around this forum, I found this post pointing to this page which gave me the basics I needed to get started.

In retrospect... I probably should've taken notes on what screws go where... I didn't realize there would be so many of such an assortment.

Except for a wire I accidently ripped from its motor solder point that needs to be resoldered (its still working fine), I think I somehow managed to get it all back together (well... almost... but confidence is high - jkp/18mar2006). These scans were made on my flatbed scanner. I had to brighten them a bit. The originals are available here. My adjusted images are here and the reduced size images used below are here. You may be able to generate clearer images from the originals by playing with the gamma, brightness and contrast. Click images for my "brightened" full size scans.

This shows the main chassis, the agitator (brush roller) motor and the power switch/recharge plug. On the main chassis there are three switch sensors: one for each wheel (two sides and nose) that activate when the wheel goes all the way down. These are all tied together and used to turn the unit off when it is picked up. The grey wire goes to the speaker mounted on the chassis. The power switch includes three leads to the battery (+/-/charge?).
This shows the vacuum impeller, housing and motor, the attached twirler (side spinning brush) motor, the front sensor array/bumper and the motherboard.

One nice thing about the layout of the motherboard is that it is almost impossible to plug a wire into the wrong place.

On each end of the motherboard is a wedge shaped channel to guide the sensor struts from the front sensor/bumper (below) precisely into place when depressed. There is an optical emittor/receptor pair mounted on each side of the wedge used to detect a hole placed in the front sensor strut (the light gets through only when the bumper is fully extended on that side).

These are the two wheels (with motors), some molding that serves to hold the rubber strip near the dust bin, some more molding that serves to hold that molding and the vacuum assemply down and two mounting "brush brackets".

One brush bracket contains the stationary "sweeper" brush on one side (brush removed from bracket in this picture). The other brush bracket contains the housing for the twirler motor (previous picture) and twirler brush. Both brackets have springs which connect to the wheels to help force them down.

These two brush brackets (two screws each) are the first thing to remove if you want to take off the front sensor array/bumper. The vertical post for the motor springs also serve to keep the front bumper sensor struts in the slots and wedge for them in the motherboard.

Both wheels contain an optical encoder wheel with an emitter/receptor for velocity detection (to make sure the wheels are turning when the motors have power).

The stuff on the left is misc stuff most Roomba owners are familiar with -- the side brush, the agitator brush and roller, a wire cage to hold them in the unit and the vacuum impeller dust catcher cover.

As to the other stuff... the springs are used to keep the front bumper extended. The other thing is a "slip clutch" which should allow the driveshaft to slip if put under extreme force (ideally, to prevent damage to the gears/motors).

The image to the right is the inside cover of the top. There are better pictures at the page mentioned above

Here we have all kinds of goodies. Some five different types of screws and lots of little plastic pieces. Included in the baggie is a spring used to hold the recharge (white) wire/terminal firmly against the battery.

As for the little plastic bits... from left to right, top to bottom...

  • 4 brackets used to secure the two wheels in place
  • twirler brush compartment cover
  • a bit of ducting leading to the dust bin
  • one of two motherboard top corner mounting/retaining bracket (black/far left)
  • front bumper strut/spring retaining bracket (black)
  • vacuum motor mounting bracket cover (black/far left)
  • agitator brush/roller holder (right/grey)
  • spinner brush (far left)
  • center motherboard retainer bracket (center/grey)
  • 2 brackets for securing vacuum/dustbin assembly in main chassis (right/black)
  • the retaining bracket for the batter terminals (lower right/black)
  • spinner motor mounting bracket cover (bottom lower right/black)
Missing are:
  • the one of the two top corner motherboard retaining brackets
  • the misc bits in the bag of gears below
The battery and the vacuum assembly stripped of everything but the rubber strip (near the dust bin).
The gears and casing of the agitator brush/roller drive. The darker region is a scan of the side of the vacuum assembly (hard to see). The thing with two hoops is a agitator brush/roller. The big thing is the side cover for the vacuum assembly (with gear pins). The other, single-hooped thing with the inward curving side is a mounting bracket for the agitator motor assembly.

They were greased, thus the bag before throwing them on the scanner.

This is the front sensor array/bumper.

On the left, I've removed the sensor array from the front bumper. Note the struts (gray) with the wedge and the hole for the optical "bumper depressed" sensors on each end of the motherboard. The wires remaining attached to the front bumper go to the infrared "virtual wall" detector on the top. The two small black pieces (towards bottom) were used to hold the side wall detector in the front bumper.

On the right, is a clearer view of the sensor array. Also shown are the emitter/collectors from the disassembled side wall sensor.

This is one of the wheels further dissassembled.
OK... now that we have a lots of little pieces... how do we put it back together again???

On the left, I've reassembled the wheels and put one into place. Probably the trickiest part of this whole drill was getting the wheels in and out of their wheel wells. I had to loosen the motor from its mounting, wiggle, twist, shove and shout. As you can see... in the process... I've ripped one of the wires (red) out of its mounting to the wheel motor. Also in this image is the battery terminal retainer bracket (next to the yellow wire on the right side of the picture).

On the right, is the top of the partially reassembled vacuum assembly. The motor to the side is the twirler motor. The string gets attached to the main chassis (center motherboard mounting bracket) when the assembly is placed into the chassis to allow some restricted rotation of the motor.

On the left, after installing both wheels the next step in installing the motherboard. At this point, only the top center motherboard retaining clip is installed.

On the right, after reassembling the front sensor array/bumper (so it is back to looking like pictures 2a and 2b above), slide the optical sensor struts in each end of the motherboard. Then, slide the two members of the support suspension over the two posts for them. Place a bumper extender spring on top of each post and then secure with the front bumper strut/spring retaining bracket (see above).

Once the front bumper sensor struts are inserted in their slots in the motherboard, you can install the corner motherboard retaining brackets. Here, I've installed the one that holds the static/sweeper brush (top). You can see where I've attached the spring that holds the wheels down. The other corner retaining bracket involves putting the twirler motor (attached to vacuum assembly) back in its housing and is shown in the middle uninstalled.

Leftover is 4 screws, 2 retaining brackets for the vacuum assembly and a bit of plastic that I found late in the process near the disassembly area (my couch and cluttered coffee table). Two screws are for the remaining corner motherboard retaining bracket and the other two are for the vacuum assembly brackets, so at least I ended up with the right number of screws even if they don't exactly pair up. Hopefully the plastic bit was from something else (???).

At this point, the twirler motor can be inserted in its corner motherboard retaing bracket and that bracket can be installed. Two screws more and the vacuum assembly drops in. Plug in the motors and tie off the string on the agitator motor (it goes up to the center motherboard retaining bracket) and that's about it. Stick a screwdriver between pins 9 and 10 of the top cover connector and verify operation. Then replace the top cover.

Given what I learned, here's some basic instructions on how to access certain components.

Last updated March 21th, 2006 - Jack Perdue / j-perdue at tamu dot edu