out of control roomba

[robotreviews]

It probably doesn't help that they also wrote "The Scheduler Remote allows you to easily preset Virtual Wall® Schedulers to activate your home robot to clean up to seven times per week. " which really gives the false impression that you need the walls to activate the robot.

If it weren't for the fact that I had done the upgrade dozens of times and actually used the remote I would never know how it worked from that description either!

[bhylak]

Yeah, I don't actually have the remote yet. I am hoping to buy one now I know I don't have to get the walls too!!!

[theghetto]

Well guys,

I took apart the roomba again and meticulously cleaned both IR emitters and receivers on both sides of the wheel fans on both wheels. There was little to no dust or grease on them, and I used alcohol swabs.

Put it back together but it was a no go. Same behavior, and during the diagnostics, again an instant red status light during both individual wheel tests and reverse tests. Again there was no flickering of either spot or clean button during the reverse test.

Could it be both emitters are burned out or weak, or could it be the motors are worn down? Or possibly something further up the line?

[vic7767]

Gordon will probably have to pull me up out of the mud here but I remember when I did a mod on my Roomba Red and added a 500 model motor to it, there was a period of time when the lead to the motor were not connected and when I ran a test 9b neither LED would light up. When I finally got the leads on the newer motor connected correctly then both motor tach indicator LEDs worked correctly. There is some dependency between all 4 sensors. I suspect the behaviour to be similar to that of a string of lights. One lamp filament opens and the string goes off. Your probably have one defective diode in the path causing a failure of both wheel tachs.

[Gordon]

... I did a mod on my Roomba Red and added a 500 model motor to it, there was a period of time when the lead to the motor were not connected and when I ran a test 9b neither LED would light up.

With the system powered, but the motor was not, there was a 50/50 chance that a blade of the chopper was blocking the IR beam-path, which caused the test to fail.

... There is some dependency between all 4 sensors.

Yes, and with the "four" being two wheel-rotation sensors, and two bump-sensors.

I suspect the behaviour to be similar to that of a string of lights.

Yes, search for schematic3 to see the four IREDs in series. in addition, notice xstr Q1 which completes the current-path through that string upon MCU command. (I can't think of any report saying a faulty Q1 had been found).

One lamp filament opens and the string goes off. Your probably have one defective diode in the path causing a failure of both wheel tachs.

While that light-bulb concept is true, its very unlikely that an IRED will fail open-circuit! Their (GaAlAs material IREDs) failure history is one of growing dimmer with time (I have had no opportunity to measure the voltage drop across a dimmed IRED. yet I would not be surprised to find it unchanged--the current passing through simply fails to stimulate emission).

The most likely failure scenario is a broken wire associated with the wheels' IREDs (the bump-switch IREDs are wired with PCB foil traces, hence are much less damage prone by handling the hardware). theghetto should examine the BLU & BRN cable wires at both ends (at the plug connected to jacks J4 & J16, and where the wires are soldered to the IREDs' pins.

But first confirm the bump-switches to be inoperative. If they happen to function OK, we'll have to look at other failure possibilities, those strictly tied to the wheels.

[theghetto]

But first confirm the bump-switches to be inoperative. If they happen to function OK, we'll have to look at other failure possibilities, those strictly tied to the wheels.

Sorry for my ignorance, but you are saying the front bumper switches are tied to the wheel tach sensors?

If you are referring to the front bumpers, they did pass the diagnostics tests without a problem. If I understand correctly, the bumper sensors are IR beams that detect a break in the beam caused by a piece of plastic pushed by either side of the bumper yes? I didn't tear off the bumper to view the bumper sensors with my digital camera, but all three bumper positions lit up the buttons without fail.

I haven't yet torn it down again to examine the wires as you suggested, but will do that next. I just thought I'd ask for clarification before doing it again.

[Gordon]

... If I understand correctly, the bumper sensors are IR beams that detect a break in the beam caused by a piece of plastic pushed by either side of the bumper yes? ...

That is correct, however the IR-emitting half (a.k.a., IRED) of each bump-sensor is electrically connected in series, and that pair is in series with the IREDs halves of the wheel-rotation sensors. Uncaring futzing around with wheel-assembly cables could break a wire and open the series current path to make all four IREDs go dark! Your robot seems to not be bothered by that issue.

[theghetto]

That is correct, however the IR-emitting half (a.k.a., IRED) of each bump-sensor is electrically connected in series, and that pair is in series with the IREDs halves of the wheel-rotation sensors. Uncaring futzing around with wheel-assembly cables could break a wire and open the series current path to make all four IREDs go dark! Your robot seems to not be bothered by that issue.

So what should I try next? Using the diagnostics, re-verified the bumpers still work even after all my messing around with the wheels. I don't see any breaks in the wires, and I've never taken the cover off this guy until I begin troubleshooting this problem. I don't have any circuit board experience other then I've replaced some giant capacitors with giant soldering tools before. Don't own a multimeter or anything like that. How far can I go with this? Is it worthwhile to try the OSMO update using remote and cable, or would that be pointless at this time?

[vic7767]

The OSMO update to 2.1 using a Scheduler remote will not offer up any help. Some skill will be needed to follow schematics and measurements using a DMM (Digital Multi Meter) $10 at Radio Shack.

[Gordon]

...So what should I try next? Using the diagnostics, re-verified the bumpers still work ...

By knowing that the Bump Switchs function, we know their IREDs are passing current.

That same current has no choice but to pass through the Rotation-Sensors' IREDs, yet those wheel sensor systems are non-operating at present.

The causes could be: a) Both IREDs have dimmed simultaneously to output useless levels of IR radiance, b) both PTs (the detectors that act on the IREDs normal outputs) have failed, or c) a combination of (a) & (b). Its rare for simultaneous dimming to occur (I don't know of any instance), it is less likely for a PT to fail. IOW, the fault is very mysterious at this point.

I see two trouble-shooting possibilities at this time:
1) Verify whether the IREDs are emitting anything visible via digital-camera conversion. and
2) Verify whether the two PTs are responsive to illumination.

...Is it worthwhile to try the OSMO update using remote and cable, or would that be pointless at this time?

OSMO is a final tactic. Once you do it, you are stuck with it.

All I (sort of...) know about an OSMOed Roomba is when a wheel-rotation fault occurs (i.e., any one of three wheel rotation sensor fails to send usable data to the MCU (micro-processor-unit)), the MCU invokes OSMO code which overrides original navigation instructions by emulating (coarsely) wheel-drive instructions that approximately cause driving that should have occurred. Since the MCU gets no feedback from the wheel-rotation sensors, if can not "know" what is actually happening.

I prefer to not go there, so others will have to tell you (or you could search the board, or possibly find advice in the READ FIRST Sticky) which OSMO unit you should use. I doubt it will be one requiring a cable.

[bhylak]

From here, it depends how much your time is worth. If your time is valuable buy a new Roomba. If you got spare time, go ahead and keep trying!!!