Anyone Work on Neato Robotic Vacuums or Know about Lidar?

[braxton]

I have a Neato Botvac D80 series robotic vacuum with an error 3000 (problem with the lidar sensing unit). Basically, when the lidar unit starts to spin up, it doesn't reach the proper speed but spins fast and then slow and then speeds up and then slows down etc. until it errors out.
Because i have a spare working unit, I was able to track the problem to a small simple board at the base of the lidar unit.

I will attach some photos shortly.

[braxton]

A few photos:

[braxton]

The 4 wires go to the main board. Power, ground, Rx and Tx.

Where to go from here??

[budm]

Since you do have working board for comparison:
1) Do you have the oscilloscope to check Rx and Tx signals?
2) You can also check Voltages of IC U1.

[braxton]

i do not have an oscilloscope but I can try to check voltages of the one chip.

I think U1 is a Texas Instruments LM393A Dual Comparator chip.

[braxton]

I also think this defective board is somehow supposed to wirelessly power additional boards on the top side of the lidar unit, as well as wirelessly communicate with the other board(s).

See
http://blog.avrnoob.com/2015/08/neat...-1-ir.html?m=1

[braxton]

It looks like the board gets the 5V signal, which powers the U1 chip and also powers the coil. I believe the coil is used to inductively power the top board, which contains the laser etc. All seems good there.

I also notice that D4 glows red but D2 does not light up at all.
Is it supposed to?

I suspect that D2 and D4 communicate wirelessly with corresponding Rx and Tx diodes on the upper lidar board.

Is it possible that D2 is bad (how would I test it?) and if so what would be a suitable replacement?

[budm]

Originally Posted by braxton

It looks like the board gets the 5V signal, which powers the U1 chip and also powers the coil. I believe the coil is used to inductively power the top board, which contains the laser etc. All seems good there.

I also notice that D4 glows red but D2 does not light up at all.
Is it supposed to?

I suspect that D2 and D4 communicate wirelessly with corresponding Rx and Tx diodes on the upper lidar board.

Is it possible that D2 is bad (how would I test it?) and if so what would be a suitable replacement?

Well you do have working board so you can see what D4 and D2 should behave, one of them may be emitter (D4) and another one is for receiver (D2). What kind of cover is installed on top of those two diodes?
The inductor output may be connected to the white connector. Where does it goes to? LIDAR motor assembly?
Q2, 3, 5, and 6 look to be for driving LIDAR motor.
How about showing the other boards and how they are connected together?

[braxton]

This link has pics of the other top boards and likely explains everything better than I could:

http://blog.avrnoob.com/2015/09/neat...t-2-lidar.html

[braxton]

I think Q9 is bad. Can anyone help me identify it.

[budm]

Why do you think it is bad since you do not know what it is? Did you compare the readings, Voltage and junctions, to the working board?
BTW, that link in your post #9 is useless, it does not show how all the boards are connected together. I guess you are not going to provide the info as requested. Good luck, I'm out.
K38 = BSS138
https://www.diodes.com/assets/Datasheets/ds30144.pdf

[braxton]

That link (parts 1 and 2) does indeed explain the connections to all the different boards in the text. The bottom board powers the top boards wirelessly and communicates wirelessly as well.
The part is bad because it is shorted across the 2 pins on the same side (not the case on the working board)

The part in question links directly to the brown wire (which is either Rx or Tx), which in turn links to the main robot board.

[braxton]

I’ve shown the connections to the transistor/mosfet.
The pin labelled G is ground. This circuit connects to D4 which transmits or receives IR signals from the top board.

[budm]

Remove it and test it off the board to make sure.

[braxton]

Originally Posted by budm

Remove it and test it off the board to make sure.

Yes I did that already. Those two pins on the mosfet are shorted (actually 40 ohms resistance). The 3 connections on the board are not.

[budm]

The pins are Gate and Source, it may nave been damaged by static discharge. Be careful when handling MOSFET, they are easily damaged by static discharge.

[braxton]

Originally Posted by budm

The pins are Gate and Source, it may nave been damaged by static discharge. Be careful when handling MOSFET, they are easily damaged by static discharge.

Thanks for making me aware of the static sensitivity of this mosfet.