400 Roomba problems with circuitry?

[newmom]

I posted yesterday but my message seems to have vanished when the system came back up, so will see if anyone out there has some information for me on this problem.

Some time ago, I posted about some unusual behavior I was seeing in a 400 Roomba. The behavior was that it was a perfectly functioning robot that I changed speaker in to find that it no longer worked no matter what I did. I put a brand new cover on it at the same time and it was ready to go. After this change, I was no longer able to get this robot to go into diagnostics, or to start. When I would click on the CLEAN button, it would show two small green lights, one in the center and one to the right. I questioned at the time whether I had gotten it stuck in diagnostics, but that was not the case. The other strange thing was that it made a one BEEP sound, when I pushed the CLEAN button, not an ehhh, even though the bumper was not on, which was unusual as you know. Okay, so I never was able to fix that Burgundy, robot. There were suggestions at that time that I followed, but nothing brought this wretched thing back into functioning status.

A month or so later, I had an identical problem, same model, all I did was change the burgundy cover. What the heck? Another robot that was functioning perfectly, ruined?

So yesterday, I had another 400 which worked perfectly but it was white and I hated the white color so I decided as long as I had these two burgundy robots that I couldn't repair, I would switch out the covers so I would have a burgundy robot as opposed to a white one. Well, as you probably have guessed, the same thing happened, so I thought Bummer but good because now I know it is the cover, but when I replaced the white cover, I found that now the white one, still displayed the identical behavior, restoring it with it's own cover, wasn't going to help.

I was able to get a hold of Vic yesterday (thank God as I was pulling my hair out) and I asked him if he thought the NEW burgunday cover was "ruining" my PCB and he concluded that that was probably right. He suggested I take a close look at the wiring in the shell which I have since done but I can't see any problems (even when using a magnifying glass). I still beleive the problem is there however.

So, does anyone have any further comments or advise and is anyone able to explain how this might have happened and if there is any likelihood at all, the the PCB (now there are 3 of them) have any hope of being restored.

[mfortuna]

Do the two different covers have different switches and LEDs? It's possible the wiring is different on the covers and the corresponding main board circuitry is different. The cover may have shorted a cpu signal directly to a voltage. Reading of the switches uses a CPU pin configured as an input. If the signal was configured as an output for a while and it was shorted to a voltage it could destroy the circuit.

[newmom]

Hi Mike and thankis for reading my post. Well the three Roombas are the basic one button 400 model. They are all identical with the exception that one was white. At least one of the two new Burgundy shells seems to have caused the problem, but short of putting that shell on another functioning robot I am unable to conclusively test my theory, and I am not willing to ruin another PCB if that is indeed what I have done.

[mfortuna]

If you have an ohmeter you could try comparing the three shells to each other. With a little work you can identify the switches and LEDs. It does seem like one of your burgandy shells will be different.

[newmom]

I will do that (or I should say, my husband will do it.) Is there any hope for my three damaged PCBs? Is there any way to determine, what part of the PCB, the damages occured to?

[TechGuy]

Are the ruined Roombas accept commands from a Roomba remote?

[mfortuna]

I will do that (or I should say, my husband will do it.) Is there any hope for my three damaged PCBs? Is there any way to determine, what part of the PCB, the damages occured to?

I did not look at Gordon's schematics. If you did damage the circuit the reads switches it could be the MCU is damaged which trashes the whole board basically.

Techguy has a great point about the remote. What happens when you try to use it to start a mission?

[newmom]

What a great question. Hurray, yes, it works with the remote. Thanks. Now what does that mean other than we know that something works. I bet you can give me more insight into the problem now?? Thanks so much!

[newmom]

Interestingly enough, the first time I tried the remote, it made the same Dreadful one beep. But when I tired it the second time, BINGO, that starting (music to my ears) tune. Now I am one to be hopeful, so my thought is, maybe it is fixed now

[newmom]

Well, now trying it with the regular Clean button, it no longer makes that one beep, nor does it show the two green lights, so I thought for sure all was lost, but tried it with the remote once more and it still works with the remote.

[newmom]

One more thing that may be important, when I use the remote to start it, and clean, there is no light now at the clean button. I have never used the remote before, so I don't know if the green light should be on as it is when you start it manually, but I am guessing it should be on?

[vic7767]

Yes, it should go on when the I'm cleaning tune is played.

[newmom]

Yes, it should go on when the I'm cleaning tune is played.

Well the robot goes just like always but it doesn't start in a spiral. It is just that the light on the clean button is not lit, which I thought was curious.

[TechGuy]

There is something wrong with the control panel on the burgundy top case. Open the control panel. Remove the flex metal contacts. Clean them with rubbing alcohol. Clean the circuit areas where the contacts sit. Put the contacts back onto the circuit board. Cover the contacts with scotch tape to keep them from moving around. Make sure that the tape covers the contact completely to prevent dirt from getting between the contacts and the circuit board.

Don't use the burgundy top on the white Roomba because it has more buttons than the burgundy.

Please report the results.

[newmom]

Thanks Tech Guy. The white Roomba and the Burgundy one, are both one button 400s. They look identical except for color. I have taken the the black cover off of the underside of the shell, the one I think is causing the problem and the contacts all looked good, but I still believe it is this bad cover that caused the problems. The thing is that no matter which cover I put on any of the three of these "ruined? " robots, they no longer work except with the remote. The white cover, will work on another robot, but no cover will work on any of the robots that had that "bad" cover on it. That cover did something to the PCB I believe.

[newmom]

Well, I am adding to this problem with another 400, same behavior.

Now I have a DIFFERENT Burgundy Roomba which was working fine. Took it apart for regular maintenance; Re assembled. Identical behavior as the other three I have written about earlier in this thread. It has the same two green lights now on the clean button. It will no longer start up when I hit the clean button. It will operate with the remote. This is the same shell it had on and the same bumper, but it no longer works. This is the fourth identical problem on four different 400 robots, (not just 400 series, but 400 models) I looked at Gordon's schematic diagrams, but I just don't have enough background to really understand them. I am really surprised as often as this has happened to me that there is no one who hasn't run into this problem. I ask one more time for any further suggestions.

[vic7767]

Have you removed the button assembly and cleaned the contact membrane surface ?

[newmom]

I didn't do that this time, but I did try it with a completely different model 400 cover and had the same result.