Is your Roomba 400 not charging? When you plug it in, does it light up but when you press the button you get no response? Here's the disassembly guide as well as a guide to fixing the U2/U4 Problem. This will also give you a chance to clean out all the Dust that builds up inside, you could clean out the inside of the brushdeck and preform the sealed bearings mod, and much more. In addition, once you open it up, you can see and clean all of the dust balls inside. Literally, the inside is usually PACKED with dust. That dust is harmful to the Roombas in many ways.

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Step 1: Intro to Disassembly

All Bumper and Cover retaining screws must be removed before attempting dismount of either subassembly. The two subassemblies must mechanically disengage Chassis fittings as a set; at least for the first few millimeters of movement. Steps in HoB apply to the following Discovery models, in which the Handle is mounted on the Bumper and interleaves with the Cover: Roomba-Discovery, #4210Roomba-Discovery Replacement, #4211 Roomba-Discovery SE, #4220Roomba-Scheduler, #4230 Note: We have not had hands-on experience with the Discovery SE, or Scheduler models, but those bots are considered mechanically identical to the #4210 Discovery, which is known to reward owners when the HoB process is used. Models #4210 and #4220 that were produced prior to, roughly, mid-2005, came with some removable parts that are called "Fender Skirts" in these documents. It can be useful for an owner to recognize whether his Roomba has Fender Skirts, because their presence provides much easier access to the drive-wheels; and also explains why two very long screws are used just forward of the drive- wheels. The image below has pointers to the joint features which indicate presence of a Skirt. A Fender-Skirt is a removable panel which spans the distance between those joints. Roomba-owners who purchased either of these Discovery models after mid-2005 should inspect the left and right sides of their bot to see if "Fender Skirts" exist on their particular unit. If no Skirt-joints are visible, no Skirts exist on that Roomba.
<p>Just purchased in Ali Express as well! will let you know once it was fixed :)</p>
<p>Hi, does the parts from Aliexpress fix the charging problem? Thanks</p><p>Nguyen</p>
<p>Didnt work for me unfortunately, but feel free to try for yourself</p>
<p>Thanks, I'll try anyway. Still waiting for the mosfets from aliexpress</p>
<p>Where exactly are the both mosfets located</p>
My roomba would not charge, it would slowly blink red while charging and then green after many hours. I unplug and try to turn on and get nothing. Plug it back it and get the same slow red pulse as if i never chargwd it. Anyway, i did exactly as this post said and i also took the advice of jasontaylor71 and upgraded both mosfets. You dont have to completly remove the board. Just enough to get at the 2 mosfets. Reassembled and it works perfectly. I almost threw my roomba in the trash but tried this fix for $7(ordered 3 just in case). Fun little project. THANKS!
<p>Thanks to JasonTaylor71 the parts from </p><p><a href="http://www.aliexpress.com/snapshot/6813300145.html?orderId=68433872188537" rel="nofollow">http://www.aliexpress.com/snapshot/6813300145.html...</a></p><p>Worked great. It was a small pain to get the board out; however very worth it. </p><p>Carlos Leon</p>
<p>Regarding step #9 only (the charger circuit repair), I'd recommend upgrading both of the failed mosfets. ss_star9 sells a set of Diodes Incorporated ZXMP7A17GTA P-ch 70V 3.7A SOT-223 for $3.32 including shipping. Current webpage is <a href="http://www.ebay.com/itm/301534034343" rel="nofollow"> http://www.ebay.com/itm/301534034343 </a> . (Mouser charges a lot for shipping so their cost is not only $3 for two STN3PF06.) The old parts could handle only 2.5A. <br>I hope this helps anyone doing this repair.<br>Cheers,<br>Jason Arthur Taylor<br>jasontaylor.us</p>
What's going on between step 8 and step 9? After step 8 there's still about 30 connections of wires, springs, mounts, etc to the main board.
I have a roomba 400 that the beater bar/brush assembly runs constantly. Pressing the CLEAN buttonturns the unit on and it goes through the cleaning motions but depressing it again to turn the unit off turns off everything except the beater bar/brush assembly. Suspect a shorted driver chip or transistor. Are there schematics available for these older model Roombas and if so where? Thank you.
great video for others having problems with charging circuit <br>i use Gordons schematic alot for repairs and upgrades <br>i have alot of roomba's for different robot designs i am testing <br>like TURTLEBOT using ROS software,and SERVERBOT design and yours <br>i like it better then my IROBOT CREATE,its low cost,plenty of room once you remove the vacuum parts and can handle up to 35 lb carring load

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