Roomba 5xx main brush motor not active / help for workaround

Problem description
my roomba 555 has this issue: main brushes don’t turn when in cleaning mode. They always did and now they don’t (without exceptions).
What I checked already:

]the motor and the related mechanics are OK (how I checked that: attached 12V to the two pins at the brush module and the brushes turned nicely, continously, as I wished they did when its mounted)/:m]
]the side brush works absolutely fine/:m]
]the side brush module receives ~14.4V (corresponds to battery voltage) (how I checked that: I started the robot’s clean mode attaching a multimeter instead of the side brush module to the connectors)/:m]
]the main brush motor receives only 2.33V ! (how I checked that: I started the robot’s clean mode attaching a multimeter to the two rightmost pins of the main brush module connector. These pins lead directy to the motor when the module is installed)/:m]

Proposed solution:
A: debug the circuit board (probably too difficult)
B: send back to iRobot (too old for warranty; probably too expensive for me)
C: use a relais with this simple logic:

IF the side brush runs -> I also want the main brush to run.
The side brush runs with 14.4V. I will connect it in parallel with the control circuit of the relais. Once active, the relais will connect the battery power to the main brush motor.

[size=4]MY QUESTION:
[/size]
[size=4]is 14.4V the correct voltage for this motor? [/size][size=4]Since the board offers only 2.33V now, the correct voltage could have been 5V, 9V or 12V…
[/size]

related, but different (other forum users’) problems:
there, the motor was broken (no response at 9V): roomba-500-series-brush-deck-module-problem-t10226#p105747
there, the motor worked (tested with 5V) as in my case but it also >>sometimes<< worked when installed properly: roomba-563-main-brushes-not-spinning-t12647#p116316

related information:
How to replace this motor (very user friendly): robotshop.com/blog/en/chapte … ent-219613
The relais I bought (2$): conrad.de/de/printrelais-12 … 03611.html
Current of the brush motor: 200-500 mA run (1250-1400 stall), see “Roomba 500 Series Service Manual” at page 46
Different robot model and motor (a fan?) but details on how to debug a roomba circuit board. Maybe someone can transfer *that *knowledge to the brush motor problem: robotreviews.com/chat/viewto … =1&t=16345

Hi,

It probably means the motor controller for the main brush motor is defective, as it doesn’t receive more than 2.33V, while it should receive around 12V.

We wouldn’t suggest you to use the voltage from the side brush motor, as the motor controller possibly couldn’t handle the brush motor load that you will put on it.

We would simply suggest you to replace the Cleaning Head Module for a new one, to make sure you don’t damage the motherboard itself. Unfortunately, we do not sell any CHM replacement, but you can easily find one on the manufacturer’s website.