Irobot 780 - dirt is stuck on the brushes

[iroombaIL]

hi,
i own the irobot roomba 780 model for just over a year now and lately it hasn't been working correctly and what i mean is this:
it goes around the house scooping up the dirt and everythign just right but when it stops i turn it over i see that all the dirt is stuck between the 2 brushes and hasn't moved in to the trash bin,
i should mention that i clean it periodically every 2 weeks including changing the filters and cleaning the brushes
i already replaced the brushes with a new set same goes for the air filters and stil lthe problem persists...

[vic7767]

Your description indicates that the brushes are not turning. Can you turn the brushes by hand ? Are they difficult to turn ? Remove the dust bin and send the Roomba on a clean run. Through the dust bin opening can you see the brushes turning ? If not try replacing the CHM.

[iroombaIL]

thanks for the reply....
1. the brushes are turning by hand;
2. i tried running it without the bin but i think some mechanism is preventing from running without the bin
3. what is the CHM?

[iroombaIL]

Your description indicates that the brushes are not turning. Can you turn the brushes by hand ? Are they difficult to turn ? Remove the dust bin and send the Roomba on a clean run. Through the dust bin opening can you see the brushes turning ? If not try replacing the CHM.

Hi,
i checked now,
the brushes are turning without the bin attached,

[vic7767]

what is the CHM?

The CHM is the Cleaning Head Module and contains the brush deck. The two rotating brushes should lift and send debris into the dust bin. The brush motor may not be able to spin the brushes correctly and at the correct RPM. One other part to check is the dust bin, make sure the dust bin motor is working. It helps pull debris into the bin.

[iroombaIL]

actually now it's working great now that i've run without the bin it works great

[Lacheby]

I upgraded to new blue CHM and AeroVac bin on my 560. I now also have the dust stuck between the brushes. I have tried 2 each of the bins and the CHMs to eliminate individual faulty part issues, (unless extremely unlucky). I ran Roomba without the bin and I can see that the brushes aren't turning. I can feel the air coming out of the AeroVac bin so assume that IS working. What to try next? I have limited testing, soldering experience, but I have a neighbor I can ask if necessary. Roomba worked well before I upgraded and unfortunately I threw the old parts away before checking if new parts worked. I had completely dismantled and cleaned all the way down to the PCB at time of installing new parts. Is there anything that I could have left disconnected, put back incorrectly that I could check?

[vic7767]

The CHM has a paddleboard that plugs directly into the main circuit board. You might remove the CHM and make a visual check that the paddleboard connector is not damaged or full of debris. You might consider running the Built in Tests to see if the brush deck motor will activate. You might try testing just the brush deck motor using a set of test leads and a battery rated at least 9 vdc.

[TechGuy]

Lacheby,

Remove the dust bin. Send your Roomba on a mission and look from behind. Is the brushes rotating?

[Lacheby]

I have read about the built in tests on other posts, can you direct me to to how I do them. Already done a visual and nothing obvious

[vic7767]

go to either website in my signature and use the contact me form to send me a message, then I can send you the procedure.

[FIN-Cole]

Hi,
I had the same problem with Roomba 780 which is now 13 years old.

Main brush does not spin. Cleaned up what ever I can, but no help.

Finally took the Main brush motor out and removed parts of it (screws, sprockets) and put the motor as near powerful vacuum cleaner as I could.

As the motor is not brushless, it creates coal dust inside the motor, which causes a small short circuit.

By spinnin the motor by hand back and forth, vacuuming again and again about 2 minutes, then offered 12 VDC from car batteru charger - and now it works again. Put parts back and iRobot 780 runs like new.

This procedure took all together about 15 minutes.

If that does not help, you need to solder off the end where the electricity cables come, take out the rotor and clean up the collector inside / on axle carefully, solder parts back and assemble again. This takes bit more time on top of mentioned 15 minutes but probably another half an hour.

Good luck.