Help - Vacuum stall? error code 3 - Roomba Discovery 4225

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Help - Vacuum stall? error code 3 - Roomba Discovery 4225

Postby tealiemonster » August 3rd, 2008, 6:57 am

I have a Roomba Scheduler model 4225 (basically a 4220 Discovery) who has been very faithful for 1.5 years.

He is now erroring out at random amounts of time into his cleaning route somewhere between 5 and 15 minutes after he has begun cleaning (no notable noises or anything). My house is wood floors, with a few small 4'x6' area carpets (short fibered.) The erroring is not consistently occuring on the wood nor carpet.
It is an Uh-Oh followed by 3 beeps. The error codes listed for the 400 roomba, series 4220, on says 3 beeps is a Vacuum Stall.

I have done some internet research, so here is where I am at:

I am past warranty so I went ahead removed the casings and did a very thorough all-over cleaning, mostly with my aircompressor, vacuum and soft dry toothbrush.

I also ran the diagnostic-test, with no notable issues. During test 13, VACUUM-IMPELLER-MOTOR CHECK, I got good, powerful airflow.

I then took apart the vacuum bin and did a detailed cleaning, removed all grit and dust, wiped down all the plastic pieces, went over the electrical contacts with a fine grade sandpaper, and WD40'd the vacuum motor's "drive shaft" (it looked like the best lube option; it appears I can't disconnect from the little fan without breaking it).

So here I am. Any advice, opinions or comments are appreciated!
Buy a new impeller motor assembly (with circuit board) on or not? It'll sit forever on full airflow in the daignostic test so I seriously doubt it's the motor, but maybe something on the circuit board failed?

Plus I am at a remote military installation outside the US and anything shipped from the US usually takes 1-2 months to get here. So if I can try something else, I am game!
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Joined: August 3rd, 2008, 6:16 am

Re: Help - Vacuum stall? error code 3 - Roomba Discovery 422

Postby Gordon » August 3rd, 2008, 12:52 pm

tealiemonster wrote:I have a Roomba... 4220 ... is now erroring out at random amounts of time into his cleaning route somewhere between 5 and 15 minutes after he has begun cleaning...
Some time ago, I published a schematic diagram of the vac-motor-driver circuit in this thread.

The interesting feature about vac-motor's power controller is: Analog motor-current data are shipped directly to Roomba's (4XXX Roombas) MCU (while most of the other motor-drivers use a local comparator device which only sends warning of a hi-limit exceedance to the micro controller unit. Schematic_8, in the same thread, shows a typical LM339 comparator section).

The MCU is then able to notice whether the vac-motor is *struggling*, for example, due to a dry or sticky shaft bearing -- in which case motor-current will *increase*; OR, if air-flow past the impeller is smaller than expected (due to some sort of blockage -- say, clogged filter), in which case motor-current will *decrease*, and the shaft will run faster.

Your Roomba is providing a good flush of air, hence, I suspect the error it is reporting is due to a mechanical over-load condition (current becomes too high after some interval of running).

WD40 is OK for a first effort -- it could relieve a *sticky* bronze-bearing condition, but WD40 is a lousy (long term) lubricant. Your Roomba may benefit by adding a single drop of sewing-machine oil (mineral-oil, 3-In-One oil) to each of its shaft-bearings.

Of course, one bearing is inaccessible until the impeller is out of the way, and you did express reasonable concern about the task of removing the impeller. Impeller removal can be done by using proper tools and tactics. I show those items in this old thread.

Surely, there is a machine-shop, or instrument-shop on base that could help you with the press-out / press-on operations.
Robot Master
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Location: Santa Ynez, CA USA

Postby tealiemonster » August 4th, 2008, 8:28 am

Thank you! your advice was very appreciated. :lol: It also gave me the extra confidence I needed to attempt that impeller removal. :?

I put the motor on a kitchen towel and had my husband hold the shaft with steady moderate pressure using a watch repair tool, while I gently rocked the impeller upward from the right next to the shaft base with a flathead. I was super cautious so it took a minute; but it came off!

You were right; there was some slight buildup of grime by the washer. I used the clipper oil from my husband beard clippers and wiped off the grime. Even though the other end had a plastic washer I went ahead and added a slightly drop there too. Then I dusted out the motor with my pancake air-compressor. After wiping down all the plastic again I put the vacuum bin back together.

Roomba seems quite happy on his 30 minute test run! hope it lasts!

Even though I don't read schematics the explaination and the links helped me understand the "overload fault" :D

Thanks again. I can't tell you how much I appreciate your expertise!
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Joined: August 3rd, 2008, 6:16 am

Re: Help - Vacuum stall? error code 3 - Roomba Discovery 422

Postby quartknee_b » June 5th, 2018, 6:07 pm

my original roomba 400 series was stalling out, so i checked out this thread and this worked:
Postby Gordon » August 3rd, 2008, 12:52 pm
and removing the impeller wasnt even that difficult.
thanks everybody!
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Joined: June 5th, 2018, 6:02 pm

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