Hoverboard won't turn off

[Red Squirrel]

One of my nephews has a hoverboard (the same kind that is known to catch on fire, but I think this particular model does not have that issue, and it's also UL approved, so there's that).  At random it decided it would not turn off.  Had to open it and unplug battery, but it just goes back to that mode when you plug it back in.  So clearly something is wrong in the control board somewhere.   It does recognize the power button as it beeps when you press it, so I know it's not the button or it's circuitry but something beyond that.

Upon some googling I found some things saying it's a common issue, and that I may need to replace two transistors and some capacitors but some rather broad info and nothing specific.  I have a general idea which ones, but just figured I'd post here in case someone might actually be familiar with repairing these.  If I do replace the transistors also wondering if I should go with something with a higher rating instead of a direct replacement?  I don't want to just be slapping in the same parts if it's actually a known issue, as they'll probably just fail again right?  The transistors are in TO-220 packages so they are decently heavy duty but they arn't for the motors as there is a set of mosfets on a heat sink that serve that purpose.

I've thought of just adding a kill switch for the whole battery, as the hoverboard still works when it's stuck in that mode where it won't turn off, but then there is not really anywhere to physically place one as it would stick out somewhat.  The built in switches are recessed into the plastic but that would be kinda hard to custom make. Finding a switch that can handle 40ish volts DC at a rather high amperage may be hard too. The battery cable is what appears to be 10gauge so probably looking at close to 40 amps max so I'd probably want to rate the switch for that.

I'm leaning towards the transistors as I read but just wondering if anyone has worked on these before and has more details.

Found this video, but can't hear the guy talk but he does point towards the parts, so suppose it's something to start with.

[Tim F]

The guy in the video mentions replacing the TIP137 transistor and two of the electrolytic capacitors next to it.

[Red Squirrel]

Yeah that's what I got from it too.  Curious to hear if anyone else has ideas or has dealt with this, given these are popular enough.  If not I will start with that.

What's interesting is that it has a bit of an iddle buzzing sound, and it seems to be generated (mayb eoriginating from) the transistor.  If I touch it, it changes the tone, like my body resistence is enough to affect the transistor.  At first I thought it was a mechanical thing but touching it with plastic does nothing.

So it may be stuck partially on, or off, and me touching it affects it.   So yeah guess I can start with that. It gets fairly warm too and so does the nearby capacitor.

[Red Squirrel]

Went ahead and ordered those transistors from Amazon.  Normally I'd order from Digikey so I know I'm getting the real thing, but already had a pending amazon order so figured I'd throw them in and hope for the best.

Got some capacitors too that have a higher voltage rating. 

I'll see how it goes.  For ~$10 I figure it's worth a shot. 

[wraper]

Is it that difficult to test the transistor and other parts with multimeter to know for sure?

[Red Squirrel]

It's kinda a pain to take apart as lot of stuff is hard wired, so figured I may as well have the parts on hand when I do take it appart.  I'll test them after just to confirm but may just replace them anyway for good measure and see if it changes anything.   While I'm in there I'm also going to throw in a resistor in series with the beeper since it's way louder than it really needs to be. 

[Red Squirrel]

The transistors finally came in and I replaced both, works!  I don't know for how long though...  if this is a known issue it seems to point towards bad design, perhaps something is causing them to blow.  But we'll see. I didn't change any capacitors as I did not feel like waiting any longer, figured I'd give it a shot and it worked fine without replacing any.  When they eventually come in they can just go in my parts pins.   Next time I'm sucking it up and paying the Digikey shipping, at least then I get it within a few days unlike Amazon. Haha.

[TheSteve]

Congrats on the fix - Digikey offers overnight Fedex shipping for 8 dollars CAD.

[Red Squirrel]

Yeah I just did not want to pay $8 for such a small order.  But should have done it anyway.   Always get sucked into ordering other stuff "just in case I need it later" anyway.

[chriskyle]

hey, that's what i was searching for..i made my own hoverboard by using this guide given over internet (though it was just a starters guide) http://www.2kreviews.com/how-to-make-your-own-hoverboard/ it worked fine for few months then suddenly it stopped turning on..initially i thought it was because of battery discharge but was no the issue...now i willl try this fix and let u know..hope it work for me the same way it did for the others