Roomba 866 error 2

[koeso]

Hi all,

I've got a strange thing going on with my Roomba 866. After cleaning the brush/roller unit and exchanging the rollers I regularly get an error 2 after only a couple of minutes of cleaning. And for a reason - the rollers are blocked by dust bunnies, hair and so on. But no idea why it does this. It still seems to vacuum (at least there's air blowing out of the "exhaust"). Has anyone else ever experienced anything like this? Couldn't find anything with the forum/group search.
Thanks in advance.

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[a1robotrepair]

Are you using OEM extractors and are they installed correctly?
Is the seal between the extractor module and the bin good?
Have you changed the bin filter?
Error 2 is over current on the extractor module.
Aftermarket extractors are usually not a good fit.

[koeso]

Thanks for your reply.
I'll have to check those things. Not sure if I used OEM extractors as they've been ordered and delivered quite some time ago. Filter is new, though and seal is looking fine.

[Teilchen]

Hi, I am new here and a quick search on this forum didn’t give any useful results except this one, and it seems it is also pretty new.
I have bought an used Roomba 886 with the Error 2 Problem. The previous user has already tried to replace the extractors cage with original replacement part. However, roomba throws an Error 2 occasionally, stopping its work.

The brushes are obviously clean, I went even further and removed the module completely along with the vacuum bin. It seems this did not disturb the robot at all, it went on with ‘cleaning’ as if everything was running as expected. However, after some minutes it came up with an Error 2 again, although no extractor module was installed.

I have tested both modules (I have the old one with me) on an external power source, they seem to be running smooth with a very little current draw, something below 1A (I can measure again if it is important). And a stall current of 5A if I would hold the brushes. The gears seem to be intakt, since rollers are rotating without any mechanical issues on both modules.

I am not sure if it is a software or a hardware issue, but I am more tending towards a main board failure. Does anyone know what I should check, or is it something that we usually do not mess around? I have some experience and all the necessary equipment at work to be able to replace an SMD component.
Is there something else I should try?

[Teilchen]

It seems I forgot to mention that the blue anti-tangle LED is lid and flashing all the time.
I did some more tests by removing the side- and main brushes completely. Again roomba was thinking everything is set, and started its movement. The anti-tangle LED was on as always and after some time roomba stopped with the error 2 again.
If this is some sort of current sensing issue, as it was proposed a couple of posts back, does anyone know which components are responsible for it?
Can anyone point me a direction where to search?
Thanks!

[a1robotrepair]

Link to links for Roomba troubleshooting:
http://www.robotreviews.com/chat/viewtopic.php?f=4&t=19533

[Teilchen]

Thanks for the links, I did check those but couldn’t find a similar case. It seems unbelievable that I have got such a seldom problem.
Is it a normal behavior that roomba continues movement even though CHM, Side Brush and Vacuum Bin are all removed. And that Anti-Tangle led is blinking? I find it strange to be able to detect an over current, but run OK with no components installed.
I have found a ‘Print Currents’ feature, it seems my roomba doesn’t consume more then 2A when running. What are the normal values?
I have found a lot of info on H-Bringe repair, but very little on the current sensing circuits, or general information what the limits are. Any tips someone?

[vic7767]

The operational current (Min and Max) for each motor is provided via the SCI port during the Built in Test diagnostics. In your case it may provide false values if indeed the current sensor is defective.

Here is an example of the brush motor info from a 980.

factory-test 16 main-brush
not (main-brush-motor-stall?) PASS
(roller-main-brush-current-ok?) mA -379 min -100 max -500 mV 16337 degrees-C 34 PASS
not (main-brush-motor-stall?) PASS
(roller-main-brush-current-ok?) mA -339 min -100 max -500 mV 16337 degrees-C 34 PASS
not (main-brush-motor-stall?) PASS
wait: (main-brush-motor-stall?)
(main-brush-motor-stall?) PASS
(main-brush-stall-current-ok?) mA -1365 min -1250 max -1470 mV 16309 degrees-C 34 PASS
(main-brush-motor-stall?) PASS
wait: (not (main-brush-motor-stall?))

[Teilchen]

Thanks for the info, I am going to try these tests out.

[koeso]

Hi again,

Unfortunately I've not been ankle to look into this for some time but now I was able to resume where I left.

I don't think my problem was brush related either.

@Teilchen, did you resolve your issue? Without having run any voltage tests myself, it seems like our problems are similar.

[Teilchen]

Ok, it has been a while... but I had some time to tinker around with my roomba just recently. BIT Test shows that the Main brush draws just a tad too much current: 630mA, with the Limit set at 500mA. This makes roomba think the main brush is stalled.
Again, I have a genue (and new) brush unit. In fact I have already tried two.
A bench test shows, that the brush actually draws only about 300mA (Using a lab power supply).
So I guess the current sensing unit for the main brush on the roomba main board reads a bit wrong. Any idea how to solve this? Or how to trick the roomba out to think it is all good? Can somebody point where the current sensing circuit is placed?
Thanks!
P.S. it seems I forgot to mention, that the main brush seems to be constantly on, I mean when the roomba is awake. If the robot is sleeping, all everything is off obviously, but as soon as I press a clean button, the main brush turned on, even if the robot is not moving
This is my only roomba, so I do not know if this is normal...
So my point is, perhaps the main brush mosfet is dead in the open state? Does anybody know which component is it?