Blinking Dirt Detect Light

dave w · Post by **dave w** » May 26th, 2008, 8:14 pm

Howdy!
I'm having an odd problem with a Scheduler. After several minutes of cleaning the Dirt Detect light will start blinking and not quit until Scheduler finally returns to charging base. When the light starts blinking, Scheduler does not go into the dirt detect dance but continues to clean normally. All motors are running and the diagnostic mode shows nothing unusual. This started after I replaced the speaker in Scheduler and used the opportunity thoroughly clean inside. I have since "recracked" the case and reseated all connectors on the motherboard, but Scheduler still blinks blue.

Anyone know what it is trying to tell me?

Thanks much!!

vic7767 · Post by **vic7767** » May 26th, 2008, 10:06 pm

Send your Roomba on a cleaning mission without the large brush installed. Does the Dirt Detect still get triggered ?

fancyfreewv · Post by **fancyfreewv** » May 27th, 2008, 11:15 am

The dirt detect sensor is that round flat shiny piece on the base of the deck. Under both brushes. I always wipe mine with a damp cloth during cleaning.

It is not an optical sensor but a sonic one - when sand or grit hits it as the brushes spin, it turns on the blue light.

If it's dirty (or as Vic says the bristle brush is hitting it in some way) it would cause it to hear and keep the light turned on.

Either that or you live on the beach and have a lot of sand in your house.

Gordon · Post by **Gordon** » May 27th, 2008, 4:24 pm

Pay attention folks, dave w has supplied this critical piece of information:

dave w wrote:When the light starts blinking, Scheduler does not go into the dirt detect dance but continues to clean normally.

I can't imagine why the Disco would do that!

Gravity · Post by **Gravity** » May 27th, 2008, 4:52 pm

When the dirt detect light goes on, and stays on for an extended period, the bot will ignore the sensor, and the light starts blinking.

I once got a piece of cellophane wrapped around the bristle brush and was continually hitting the sensor. After about a minute the light started flashing and it stopped the dirt detect dance.

dave w · Post by **dave w** » May 27th, 2008, 9:19 pm

Gordon, thanks for reiterating that. It did seem to get lost.
Gravity may be on to something. I have not actually seen Scheduler the moment the Dirt Detect light comes on. Only that I have started Scheduler normally and come back in a few minutes to find the Detect light blinking away, but Scheduler is moving in straight lines as normal. I clean Scheduler with a shop vac after every run and this includes removing the brushes and vacumming the surface of the tranducer. So if it is a tranducer problem, it is nothing obvious. I had not thought of testing without the bristle brush so I have some avenues for troubleshooting.
So THANKS! to all.

BTW one last question to any of you Reverse Engineers.

A few weeks ago the vacuum motor in our Red quit. I traced it to an open driver transister and replaced with a standard 2N2222 (actually a Motorola M9570 which is an "in house" general purpose NPN in a TO92 package). The new driver blew within a week (Red is used daily for one hour in the morning and one hour in the evening). How much current does a free wheeling (clean, no hair, dirt, etc binding the fan) Roomba vacuum motor draw?

Thank very much!

vic7767 · Post by **vic7767** » May 27th, 2008, 9:43 pm

I tested a Roomba Red vacuum and at 16 volts the motor pulls .24 amps.

dave w · Post by **dave w** » May 28th, 2008, 6:27 pm

Vic7767

GREAT!!

Thank you very much for your help! Your data says my 200mw junk box replacement transister just didn't have the ooomph necessary. I'm surprised it lasted as long as it did. A trip to Radio Shark is in order.
Very much appreciate your time!