Asked — Edited

Roomba Discovery 4200 Series?

Hello,

I'm in the process of cleaning up my shop and I came across this Roomba that was given to me a while ago, the guy who gave it to me said that he had bought 2 new battery packs for it, it would charge the first time, then after that it wouldn't charge the battery anymore.

So I started taking it apart this morning and man what a mess this thing is. It sounds like it was overcharging batteries to me, but has anyone else run into this with the roomba 4200 series?

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#1  

Mine worked fine until it fell off of the workbench. I picked it up for $4 at Goodwill. But, it seems to be weak. Could be the battery. I put 10 lbs on it and it had trouble moving. Of course that was after it fell off of the workbench.

It was a nice little unit. I liked the color of it.

Just my 2 Cents.

#2  

I was thinking that, but two new replacement batteries doing the same thing makes me wonder if it's not something else.. Have to get it cleaned up first..

#3  

After googling around for a while I found that there was a common issue with the discovery roomba, mosfets U2 and U4 were known to fail internally, looks like they cost $1.00 each through digikey...

#4  

There are several MOSFET replacements that can be installed on the Roomba PCB. The MOSFETs are SMDs SOT-223 style. There is also a much heftier TO-220 MOSFET that can be installed using some 26 gauge wire so that the devices can be re-located within the Roomba because they won't fit in the original location. More info can be found here: http://vic7767.com/

#5  

@Robot-Doc - nice find! I'd rather replace the SMDs with the TO-220's myself, I actually have a bunch of mosfet's, but they might be a little 'much', they are 60V 30A.