Roomba 650 right wheel turns only backwards

The very latest news and updates for the iRobot Roomba robotic vacuum, the Scooba Robotic Washer and the Dirt Dog workshop sweeper. All discussion and troubleshooting questions go here.

Roomba 650 right wheel turns only backwards

Postby 170watt » July 4th, 2018, 10:15 am

I bought a defective Roomba 650 that showed Err3 message. However, once I got home, I realized I’ve got a Roomba with more issues. I noticed that the unit turns/circles only one direction.
I performed a few BITs and noticed that the side brush (#19) does not work as well, and also test #13 (right wheel) had also issues – the right wheel turns backwards, instead of forward! The other wheel/brush tests seemed OK. Also, the bumpers tests are OK.
Anyway, I cleaned the board, and the Err3 went away, seems to charge the battery – although after charging stops, instead of full green, the start button turns off (when I remove the unit from the charge base, it turns green. Go figure!)
Anyway, I also performed a quick/superficial examination of the N3018SD MOSFETs and noticed that one of these, corresponding to the side brush didn’t seem OK, so that may explain why the side brush isn’t moving at all.
I replaced the right wheel module (from another Roomba) and the right wheel continued to turn only backwards, so the issue is with the main board.
Any suggestion as to what may cause the right wheel turn only backwards? Could be the H bridge, or something MCU related?

(Note: This newer MOSFET H bridge arrangement on the 600 series is new to me, I was used with the older BJT transistors, it was more straightforward, when it comes to troubleshooting. Is there a place in the forum where this is discussed? Or even schematics?).
170watt
 
Posts: 14
Joined: July 11th, 2017, 12:53 pm

Re: Roomba 650 right wheel turns only backwards

Postby a1robotrepair » July 5th, 2018, 8:07 am

The 650 circuit has 2 versions,
2012 through 2015,
and the later 2015 and up.
For both, BIT 11 will tell you which battery sensor circuit, circuits have failed.
For the earlier versions, go to this post and read under R3 the links to the posts you need to troubleshoot your 650.
http://www.robotreviews.com/chat/viewtopic.php?f=4&t=19533
Fix CE3 first. Without charging the bot is worthless.
Wheel module next.
The front brush is either the s8550, s8050 H-Bridge transistors or a Vbat, GND Trace to the emitters of those transistors, most of the time.

For the later 650 board, it is a mixture of the early R3 boards and the 700/800 series boards.
Roses are red Violets are blue Poems are hard Flowers and Chocolate
http://www.daycounter.com/Calculators/
a1robotrepair
Robot Master
 
Posts: 945
Joined: October 14th, 2013, 8:40 am

Re: Roomba 650 right wheel turns only backwards

Postby 170watt » July 5th, 2018, 8:38 am

Thanks so much for your answers!
The Err3 was resolved just by cleaning the board with isopropyl alcohol.
Unfortunately this Roomba has a 2015 PCB. It has a pair of DMN3018SSD (30v dual n-channel enhancement mode MOSFET) for each bridge, and one DRV8701 (DC Motor Full-Bridge Gate Driver).
I could try replacing the MOSFETs, but – assuming that the drivers are at fault - I have a problem with, as I can’t find these on eBay.
My question however, is this: since during the #13 BIT – where the wheel is supposed to turn forward – the right wheel turns the other way around (backwards) – is this indicative of anything? I mean if no turn, I would think it’s the H bridge problem. But backwards? Could that be explained by malfunctioning driver?
By the way, the area look nice and clean, no traces of burnt components.
(For the second issue, the side brush not moving – I think that the MOSFETs are the issue.)
IMG_0059.jpg
170watt
 
Posts: 14
Joined: July 11th, 2017, 12:53 pm

Re: Roomba 650 right wheel turns only backwards

Postby a1robotrepair » July 5th, 2018, 9:12 pm

The full bridge gate driver makes trouble shooting the circuit easier.
DRV8701 datasheet http://www.ti.com/lit/ds/symlink/drv8701.pdf#page14
I noticed on page 13 that all the FETs are N-channel in the functional diagram.
The drawing you seek.
What are the markings on the FETs?

Your pic was good enough to tell. 3018 dual n-channel mosfet.
Like this one: https://www.mouser.com/datasheet/2/115/DMN3018SSD-278014.pdf
Roses are red Violets are blue Poems are hard Flowers and Chocolate
http://www.daycounter.com/Calculators/
a1robotrepair
Robot Master
 
Posts: 945
Joined: October 14th, 2013, 8:40 am

Re: Roomba 650 right wheel turns only backwards

Postby 170watt » July 6th, 2018, 8:44 am

OK, thanks for the documentation and suggestions!
170watt
 
Posts: 14
Joined: July 11th, 2017, 12:53 pm


Return to iRobot Roomba and Scooba Chat

Who is online

Users browsing this forum: Chonlameth, Flole, im1kissfan, mfortuna, Miles267, RockinRay, rotorwash, sondejmarek and 316 guests