Best posts made by vulkito

@ando Hi there! I had to replace that same capacitor. it is a 1uF 2012 package and I used a 10V rating. You can buy them in Newark

https://www.newark.com/kemet/c0805c105k8ractu/ceramic-capacitor-1uf-10v-x7r/dp/64K2894?st=2012 1f capacitor 10v

Hi all! I´m new to this forum and new to the onewheel world! I just got a faulty XR (very bad condition) and I´m trying to resurrect it... which looks challenging at this point. I saw that there is a high level of tech knowledge here, so I wanted to see if you could help me on this:

HW: 4212 (lucky me)
SYMPTOMS: Error 16; battery not charging.
FIRST GUESS: BMS fried

Upon opening up the battery box, I see C11 missing, which is a 1uF capacitor. I also assume that the voltage should be for the cell, which should be 4.5V (I saw on other designs that the voltage covers the total voltage of the entire battery pack -63V-). If my assumption is correct, I would go for a 1uF 10V ceramic capacitor.
I checked RS-485 comms. Resistance appears to be OK (121 ohm between terminals). However there is continuity between terminal 5 (GND) and 8 (Vcc) in the SN65HVD1786. Looks like it is fried and has to be replaced. C33 it is also shorted and has to be replaced (100 nF - 220 nF 6V ceramic capacitor)
I also checked the PIC to see the status of it, since it is the driver of the comms. Terminals 16 (Vss) and 17 (Vdd) are shorted. BUT I didn´t check yet if it is due to the capacitors installed between these pins (C34 and C35 which I honestly don´t know the value) OR to a short on the PIC internals. If I decide to replace the PIC I would have to program it with a firmware... which I do not have. Those capacitors are installed between Vdd and Vss. Difficult to see the traces, but I assume it by the position and continuity.
On the controller side, SN65HVD1786 is good and R=121 Ohm (at least something good). I assume the controller side is OK.

So at this point I don´t know how far should I go with this because I have some limitations (never soldered SMD, BMS PIC Firmware missing). I have some questions to see if you could give me a hand...

1.- Does anybody know if the firmware for BMS 2110 pcb is available? or any custom firmware to flash? (I can program PICs, that should not be a problem, but I do not have any .hex)
2.- Has anybody tried to flash the PIC of a 4212 BMS with an older BMS PCB? (i.e. 4209)
3.- (this is the tough one) Does anybody know the value of the C34 and C35 capacitors? Are installed between Vss and Vdd of the BMS PIC ucontroller, and are REALLY tiny. I cannot find information about them.

Besides that, the XR has most of the screws missing, no bumpers or fender. I guess I will spend some time on this one...

Thank you guys!!!

Replaced max ic, installed missing capacitor. E16 is gone! Which means that max ic and pic are supposed to be ok.
However, the OW only stays on when plugged. As soon as i unplug the charger it turns off. I see that the area on the top of the balancing connector gets hot, but that’s a bunch of resistors mostly…

I saw some questions in regards with how to identify the part when working with SMD components. Yes, it´s a pain in the neck; manufacturers do not have space enough for all the letters/numbers on the part itself, so they put a very "random" reference and we just deal with it.

No worries, everything has a solution except death (as of today). To identify the SMD part just follow the next steps:

1.- Identify the SMD component that is faulty.
2.- Identify the reference on the silk screen.
3.- Grab a cold can of your favourite soda/beer.
4.- Identify the package the component has (SOT-XXX). This could help: https://en.wikipedia.org/wiki/Small-outline_transistor
5.- Now go to https://smd.yooneed.one/
6.- Click on the button with the same two first digits of the reference identified in (2)
7.- Search for the entire reference on the list. It will most likely have several options for the same reference. Here is when you have to use the information of (4), since there are not many options for the same package.
8.- Once identified, just drink the can you got in (3).
9.- (OPTIONAL) put on your shades. Now you will feel cool AF; you cracked the code xDDDD.

EDIT: SIZES
When searching for replacements, it is important to take into account the size of the component since one component for an specific value con be manufactured in different sizes (i.e. capacitors).

This chart can be handy:

https://www.topline.tv/sizechart.html

I know that we will see exceptions (everything has at least one exception), but it is a good start. I hope it helps!!!

@lia thank! Well, for the cells voltage… didn’t measure -_-u. It was only to see the voltage for the capacitor; somewhere bigger than 4.5 should be fine.

To be honest… i don’t know what happened to this board, the previous owner opened it and i don’t know what was done… but it’s a disaster. After all these issues i was expecting a “lucifer was here” on the back of the board. Once i arrive home i will take a picture of the board. I think that if this bms pcb is the same as an older one i could get the fw and flash it. But, as you say (and nkotb knew) step by step. I’ll start with the rs-485 replacement and i will also desolder the capacitors to see if it is on the pic or not.

@sirgu thank you! I hope so… it is my opportunity to finally have my one wheel! Hahaha

bms 2110 here is the bms board. For the record xd

@lemur i hve a couple of pics in my cart already hehehe. But now the question would be if i can install a new pic (flashed with an old firmware revision) and would work (+owie). I would say that the hardware at logic level is the same (but i do not have a board to compare). If this is the case i can search for a 4209 firmwware and test. The bms is already out, soooo i guess there is nothing to lose xD

@lemur i can see them on the link. Does it guve you any kind of error?

Ok, some news:
C33, c34 and c35 are ok. Removed from the pcb to try to isolate the short with no luck (at least i measured the cap values).
I desoldered gnd from the 1786 and looks like that this one is not shorted either. I still have a short between gnd and vcc, so either the pic is shorted or i think i should go to the voltage regulator (which i have to look for on the power area). This sounds promising… (i’m starting to lose faith…)

Ok, after injecting V to the rail with my power supply the limitation was triggered and nothing was hot. I connected everything back (batt and controller) and turned the ow on. Error 16 came up and the max was really hot compared to the rest of the components. I guess we got the culprit. Now we’ll see how the replacement goes. I’ll keep you posted!

@lia was the max battery management chip (max 14921). I wasn’t expecting that…

I reveived the parts! I’ll get to work tonight. Finger crossed!!!

@lia correct; once the charger is unplugged the ow does not turn on. Which i’m still thinking why could this be possible. The only thing i can think of is that the bms is not allowing the voltage to pass to the controller for some reason (which should be related with comms i think… but that’s a noob assumption xD)

And i’m actually stuck on the ics from the upper side of the balancing connector (i want to check them since there is a lot of heat in there). The only thing i can see on the silk screen is M8t, which if i search looks like it is a sOT-23 and these ones have 6 pins, so it is not the same thing. I saw one that has 6 pins but it is a 9V voltage regulator, which i think it is not the same one. Finally i found a 2N7002PS which has M8% marking (% for the manufacturer site code) and is a 60V,320mA Mosfet. This one could be an option but i’m kind of guessing here. Any ideas out there? If it is a mosfet the pins should be grouped (3-2-1 maybe?) i should take a look to that… but tomorrow; time to go to bed xD

I actualli saw a post about M8t … hahahaha viva la search!!

@lemur thanks! Actually error 16 is gone (hopefully for good!). Now the board only stays on when plugged.

Taking into account that what i´m experiencing now are power issues i decided to not to plug the board again for now (I don´t know if i can burn any other thing) and take a look into the main MOSFETs. SO:

On the left side we have the 240N10F7 and looks good. But on the left side I found what apparently is a 20N08N5 MOSFET that is gone. I took a look into the resistance and are pretty low:

D-G: 2.4k
D-S: 0.2
G-S: 2.4k
S-D: 0.2
G-D: 2.4k
S-G: 2.4k

With these low values I thought that maybe I turned on the MOSFET when measuring on the gate because I have the same resistance between D-S and between S-D, but I put the negative of the multimeter on it to try to turn it off (just in case) and the values are still the same as above. In any case the rest of the values are also pretty low I think; G-S and D-G should be on the MOhms and are 2.4kOhm. I´m not still confident because when I plugged the OW the other day i didn´t feel any of the MOSFETs getting hot and a short as I´m seeing now could turn that component into a frying pan. I should have the short elsewhere.

On the other hand this maybe could explain those power issues. I´ll keep checking things and once checked i will connect everything and short the blue-black wires on the connector and also will measure voltage values on the MOSFETs.

I made it. Heat, flux, more heat, more flux… more heat… and more everything. That was a hell of a mosfet. The solder these guys used is hard to melt, even when cleaning the pads. Well… another month to receive the parts 🥲

@lemur yeah… one of the legs lifted up a little bit the pad, so this week i’ll have to fix it with some uv resin. I checked the components next to it because i was concerned i destroyed them with all that amount of heat. Looks like those are ok, but… let’s see when the part arrive. This is taking its time xD

@loaffette LOL
I thought on the wire but then i remembered all the problems i had in the past with vibrations on things that move and i will try to repair the pad with epoxy and copper. If it doesn’t move i don’t have to worry. On motherboards that are usually static there is no problem, but i’ve seen broken cables just due to vibrations, which is a pain