Need diagnostic help on 550

Botchaser · Joined: 20 Dec 2005 Posts: 9 Location: Twin Cities, MN

Read the FAQ.s, Wiki and searched but am not finding the answers to my problem.

I recently (2-3 months) bought a new Roomba 550 and yes I did so from Ebay. :( The unit started it's demise by intermittently failing to run in a straight line. It would curve or arc to the left. It did not happen often and would self correct. Also the last two runs, I came home to find the unit just stopped somewhere in the kitchen, no lights at all. I just assumed he ran out of power and couldn't find home base but today the left wheel is completely inoperative. There are no beeps or lights. From the FAQ's, it appears there is no diagnostic mode to put the machine in like my old Discovery? Am I possible looking at a bad wheel module? If so, where would be the best place to purchase a replacement?

If this has been discussed many times previously, I apologies and would appreciate a redirect to the thread.

vic7767 · Joined: 14 Jan 2006 Posts: 3270 Location: Louisiana

There is a diagnostic mode that you can place the 5XX models into but it requires a Create Comm cable or Rootooth interface connection to the SCI port on your Roomba. In the description of the drive wheel not running I don't believe the diagnostic program will add any info for you. You can place the Roomba into the demo mode and obtain the same info.

THe drive motor failure is a high runner failure on the 5XX models. Since you got it on ebay I guess you are saying there is no warranty. If so you can order a drive wheel module from Chris at RoombaExchange.com and replace the one that is failing.

You might want to try a system reset and see if that resolves your issue.

Botchaser · Joined: 20 Dec 2005 Posts: 9 Location: Twin Cities, MN

Before ordering a new wheel, just wanted to add that I took the wheel out and applied power to it using a 9v battery and the wheel did turn very slowly. Took it apart and blew it out with compressed air but it wasn't dirty inside. Replaced the wheel and same problem exists. Also the wheel is inoperative in the demo mode so I guess a new wheel module is in store for me. How do you do the system reset? Is it as I suspect that you remove the battery and press the power/start button? If so, when I had it apart, I did this and held the button for 30 seconds.

Thanks for your help.

vic7767 · Joined: 14 Jan 2006 Posts: 3270 Location: Louisiana

Pulling out the battery and pressing the clean button is one of two ways to perform a reset on your 5XX model Roomba. The second way is to press down both the spot and dock buttons at the same time for 10 seconds, release the buttons and listen for the reset tune to play. Your drive motor may be suffering from a cold solder joint. If you are handy with a soldering iron you can attempt to reflow the leads on the motor.

Gordon · Posted: June 14, 2008, 7:09 am Post subject:

Botchaser wrote: Before ordering a new wheel, ... I took the wheel out and applied power to it using a 9v battery and the wheel did turn very slowly. ...{however} the wheel is inoperative in the demo mode so I guess a new wheel module is in store for me. ... I think your guess is premature!

Use of a 9V-battery to power Roomba motors is only a test for indication of life!

A 9V-battery is simply too weak to run any Roomba motor up to speed --- IOW, you should expect slow running. That battery's voltage is at least three or four volts too low, and its not meant to deliver a third of an amp into a load! 9V-battery details are here:
http://en.wikipedia.org/wiki/Battery_%28electricity%29#Battery_capacity_and_discharging
... translation on request.

The data you have in front of you, right now, points to a fault in the wheel's driver-circuit (a main-elex problem!).

I think it would be prudent for you to remove the operable wheel-assembly and run its motor with the same 9V battery. See if that wheel runs at about the same rate as the suspect does. If that pans out, you need a robot transplant, not a wheel-module.