Bay Surfer Posted August 17, 2016 Share Posted August 17, 2016 While riding off road put the Bot in a stream, flooded the Controller compartment, the wheel beeped the rest of the way out of the woods and finally turned off after getting back to home. Dried the board off, cleaned the muck and dirt off, washed with alcohol, dried again, board would turn on, beeped then turn off, phone would also connect. With controller plugged into unit wheel when turned staggers/thumps, unplugged turns smooth. Checked the MOSFETS in curcuit one is shorted out of the 6, so it seems most likely reason. Want a new board, but seems no one has one in the US, so prob it will have to come from china, by slow boat. So decided why not replace the MOSFET while waiting for fun, well the exact MOSFET I can only get like only 1000 of them, so ordered 6 of a different brand of the same Volt and Amp rating, But could not match the Ohm rating. Question can I get away just replacing one, or should I replace all of the MOSFETS. Link to comment Share on other sites More sharing options...
US69 Posted August 17, 2016 Share Posted August 17, 2016 My 2 Cents: You should replace the complete board...nothing else! Soldiering one Mosfet or even all will not be as good as needed.....You Need them all to have the same resistance, otherwise it is a question of (short) time, when the next will burn... Also you do not know if the board is not damaged more than the one mosfet....so: Nope! Dont do it! Link to comment Share on other sites More sharing options...
OliverH Posted August 17, 2016 Share Posted August 17, 2016 The motor inside could like horror with a lot oxid everywhere coming. I've seen a Firewheel which was destroyed in water (stream/ creek). Link to comment Share on other sites More sharing options...
Bay Surfer Posted August 17, 2016 Author Share Posted August 17, 2016 Pretty sure water did not get in the motor its sealed pretty good, on the other hand the controller and battery compartment are not, only the controller compartment was flooded. Yes I do want a new board, ordering one, Jake at ForwardCa is searching for one close, repairing the board is for fun!, and to say I did it. Not Jone'sen to ride I still have a E+ and a Hurtle generic to ride, But for some reason the C+ is the best wheel to ride off piste. On a side note, the controller is a 1.3 version same as a E+ by looks, but I have been told that a serial # needs to that of a C+, I think I an change that in the firmwear. Link to comment Share on other sites More sharing options...
esaj Posted August 17, 2016 Share Posted August 17, 2016 I wouldn't put too much trust on a home-refurbished board, but purely as an experiment, it'd be interesting to know if and how well the board works afterwards. At least older Ninebot -boards used 75NF75 -mosfets, don't know what the newer ones use. Anyway, 75NF75's are available in small lots for example from Aliexpress, although when buying the cheap stuff overseas, you can't actually be 100% certain that they're what the packaging says they are Ie. they could be the genuine article, factory rejects, re-stamped cheaper mosfets, used ones desoldered from some scrap or even fakes For my hobbyist-stuff, it doesn't really matter that much at least most of the time, but on a wheel that's supposed to keep you balanced it might a "bit" different matter Link to comment Share on other sites More sharing options...
Bay Surfer Posted August 17, 2016 Author Share Posted August 17, 2016 Ya Aliexpress rocks bought 6 STP120N10 for cheap with free fast shipping to the US, will see If they work. Prob replace all the Mosfets, but would be nice not to mess up all the solder joints if I don't have to. Also resealing the board after replacing the Mosfet"s is also a issue. Link to comment Share on other sites More sharing options...
OliverH Posted August 17, 2016 Share Posted August 17, 2016 1 hour ago, esaj said: I wouldn't put too much trust on a home-refurbished board, but purely as an experiment, it'd be interesting to know if and how well the board works afterwards. At least older Ninebot -boards used 75NF75 -mosfets, don't know what the newer ones use. Anyway, 75NF75's are available in small lots for example from Aliexpress, although when buying the cheap stuff overseas, you can't actually be 100% certain that they're what the packaging says they are Ie. they could be the genuine article, factory rejects, re-stamped cheaper mosfets, used ones desoldered from some scrap or even fakes For my hobbyist-stuff, it doesn't really matter that much at least most of the time, but on a wheel that's supposed to keep you balanced it might a "bit" different matter For the Firewheel I've a guy over here able to replace the MOSFETs of the Hopemotion board. Link to comment Share on other sites More sharing options...
Pagsy Posted August 17, 2016 Share Posted August 17, 2016 I would replace the whole board .. I did it on my E+ ... note that I needed a passcode to activate the new board with my serial #. it is given by ninebot only (thru email or phone call I guess ) Link to comment Share on other sites More sharing options...
lizardmech Posted August 18, 2016 Share Posted August 18, 2016 Replacing the fets may not work, they often take out anything used to drive the gate and current sense if it's not isolated. I don't think 9 bot even has proper gate driver IC so it's possible for the damage to spread all the way to the MCU PWM output pins. Depends on which fet blew and if overcurrent or BMS shut it off quick enough. Link to comment Share on other sites More sharing options...
Bay Surfer Posted August 19, 2016 Author Share Posted August 19, 2016 W'ill see, Mosfets will be here before the New controller board. But, I d'ont think the MCU was effected the controller stayed on as long as the wheel moved, plus I did get readouts of temp, voltage etc, through bluetooth. Only one MOSFET was shorted out of the 6 testing them out of circuit. If it works should be fun testing the wheel, I think the speed limiter function use may be good idea. Had to ride 2 miles at 10kph because of low battery on my E+ yesterday, that was tough! Link to comment Share on other sites More sharing options...
Bay Surfer Posted August 29, 2016 Author Share Posted August 29, 2016 Received Mosfets from China, soldered them in, put board back in. ITS ALIVE!! Wheeled for a while, speed same, tested torque up steep hill in grass got the angle warning beep, but it held in there. Well I think I may wear some safety gear till the new board arrives from China just in case. Link to comment Share on other sites More sharing options...
esaj Posted August 29, 2016 Share Posted August 29, 2016 Good job! It's also a proof that the mosfets can be (at least in some cases) be replaced and get the board back working... although how long it will work is a whole another matter Could be a day or could be a year (or less, or more, or anything in between )... Link to comment Share on other sites More sharing options...
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