repairing 360 s6 vacume cleaner robot with stuck radar

[Matthieu vK]

Hello,

I got my hands on a 2e hand 360 s6 vacuuming robot i wish to repair.

Unfortunately, a common (and mine) problem is that the radar, used for navigation is not working.
a second unfortunate thing is these problems seem to have many different causes, from dirty lens, to stuck hairs so it can't move, to broken down radar module to a faulty PWM (mosfet?).

the issue I am dealing with is what I believe to be a faulty PWM.
I have come to this conclusion as this seems to be an issue that others have dealt with also, but I have not found anyone with a solution. so this topic might help others too!
The previous owner replaced the radar module completely and still had the same issue afterward, so no improvement there.
This is basically when he gave up repair attempts and I took over hoping I could manage, also I tend not give up quickly.

the entire assembly consists of basically 3 pcb's
1) main board that ofcourse controls the main functions
2) board that controls the rotation of the radar module (and also has the light detection sensor on it !?)
3) board that controls the radar function itself.

I will add pictures of the 1) (part thereof) and 2)

what have I done so far:

1) Checked that the module spins freely, so there is no mechanical obstruction

2) tested the electromotor.. by putting power directly on the two motor terminals bypassing the pcb, and the motor (and radar spun freely. so nothing seems to be wrong there.

3) I put power (5V) on the PCB at the point where normally the PWM wires come in, so i connected 5V and ground to an external power source. obviously, the radar would not spin..
but when tapping the 5V plus to the PWM pin, it did (ofcourse only when tapping)

4) watched plenty of youtube videos' trying to find people with similar issues and see how they get things solved. Unfortunately, I found only 1 video, (a german one) that fit that description.
https://www.youtube.com/watch?v=9zS4iptAZIQ&t=1485s,

but, well let's say his way of working wouldn't be mine, also.. apparently the day after the repair, the thing failed him again, also his board that controls the rotation is different than mine.
basically he replace / upgrade / parallel attached an mosfet, but i can't seem to find any mosfet on my board at all, so nothing to replace,

my next step is to take the radar module as it is and connect it to an arduino and use that to rotate the module by code, this should be fairly easy. just will be a while before I can get around to that.

The second next step is to test the PWM output of the mainboard and see if there is any PWM signal at all, I expect this to be more complicated as it sound as
1) I never seen it function normally) and
2) I don't know if it does when connecting when the thing when disassembled, or if some safety measure is in place to stop it from working anyway.

if the issue is mainboard and not radar module related, I can easily order a new board. but this would be a waste if the issue is not in the mainboard and / or there is something wrong with the radar module that causes the mainboard to damage.
also replacing a few components is cheaper and gives more satisfaction in the end.

any part on the rotating boards, that could've been a mosfet
u6: xkt 412
u5 : xkt 335
u14: 393a BQL
u16: 662K

there is no part, on the mainboard parts there that I believe to be a mosfet (functional / non functional), I specifically tested
q13, q15, q22.

any suggestions here would be highly appreciated.

I have tried to be as concise as possible, if I missed something, please ask for it and I will answer asap.

[CapLeaker]

I've got a an Roborock S5 that has the rotating lidar. A few years ago, the robot vacuum would go a couple of meters then shut down with some sort of error which I can't remember anymore. The lidar on mine wasn't stuck solid, rather the top bearing on the motor dry.
What cured mine: I disassembled the lidar unit and took the motor out, I took the motor apart as far as I could and cleaned it with IPA. Then I lubed the motor up with some fresh quality oil that doesn't gum up an let it run on my bench power supply. Repeating this step lubing and running for a total of 20 mins. Then I put the ole Roborock S5 back together and the problem never came back.

Checking the motor that it spins, may not be an indicator that the lidar works, because it needs to run the lidar at a certain speed. If the motor spins but draws too much current, the robot should shut down.

As I understand it, your case the motor spins on a PSU, but you don't get any power from the main board to the lidar to make it spin when connected to the robot? First I'd grease / oil the top and bottom bearing of the motor on the lidar. Watch the current consumption on the bench PSU. If the current consumption is lower after lubing the motor, there was a problem and would show sooner or later. Then you got to put the robot semi back together and see what it does. Like I said, mine ran like a meter or two before shutting down. If the lidar doesn't want to spin on the robot, well I guess you have to figure out why there is no power going to the lidar unit.

upload some pics of the whole robot.

[Matthieu vK]

CapLeaker
thank you so much for your reply!

I completely agree with you that the issue of bad lubrication of the bearing can be essential.
I had the feeling that the Lidar unit was replaced, so I checked it with the seller and it is indeed the new one.
Therefor this unit still has proper lubriation (for now)
According to the seller, it's an original part with the same partnr. but I believe many parts are available from different manufacturers,
sed in different vacuum cleaner models that do the same job. All that is sent back is a UART signal anyway (with info on the measured distance of measured by the lidar and the rotation speed)
o I believe this to be of no real importance for this repair at the moment.

On the other hand, I finally did manage to find the mosfet (partnr O7, can't believe how I missed that)
I had no stable reading between the drain and source, it kept fluctuating between a reading and no reading.
So I believe that this part is faulty for this new Lidar unit, I took it off to test of board. but unfortunately, it broke into two pieces !?
Mainly my fault I believe, But it could also be that the unit had indeed a real issue.

so if the original unit had dried up, and the new unit had a faulty mosfet, this would both give similar effects.

Additionally, the previous owner did home 'repairs ' and I believe that a short might have been created. Just not sure if this is a cause / or a effect (and a different cause)
So I am still trying to get an answer on this question, could help me sorting things out.

I also believe that the previous owner might have swapped RX and TX, this would've given the effect of no communication between the boards of course, and therefor also no rotation.

so next steps...
1) wait for the mosfets to arrive, test and replace them.
2) test the Voltage out of the mainboard and verify Rx Tx connection and uart signals to verify the mainboard is still functional for the lidar control part.
3) pre-lubricate the motor and bearings of the unit for longer lively

Unfortunately there is a waiting time for the mosfets' so here hold my workings on this unit for the moment untit they arrive.
I will post back afterward, to keep this thread up to date.

Kind greats

Matthieu