alapon77 Posted July 3, 2021 Share Posted July 3, 2021 Hi. I'm attempting to repair my brother's KS16s after it died on him in the field doing some steep trails. He got it working again after a couple days wait, but had some red LED patterns (a fault code, I assume). It only worked in Beginner mode AND it only goes a fee feet before powering off while riding (yikes!). I took it to my workbench and examined the motherboard and found no damage or burns anywhere except the positive leg of the larger capacitor. The leg was disconnected and showed a little burn residue. The capacitor itself didn't appear 'swollen' or blown so I assumed it was still good. I re-soldered the leg (and may have accidentally shorted it in the process) and turned it back on and the thing went from 0 to 25mph in under a second! It literally jumped up and did a somersault. https://photos.app.goo.gl/K1imWDH6Y2cRdnin9 Assuming the capacitor may be the culprit, I ordered a new one on eBay (upgrading from 80v to 100v). Misjuding the polarity of the capacitor (don't ask... I know now), I temporarily connected the new capacitor with alligator clips (in reverse) to test and unsurprisingly when I connected the battery pack to the power supply harness, I arc'd that connection with a nice little short. Not knowing if the capacitor was damaged or not, after learning what I'd done, I corrected the polarity and reconnected everything. Turned on the EUC and it did the same somersault again. I've since ordered another capacitor but haven't installed yet. Do any of you have any thoughts on this? Does it sound like a capacitor issue or is this a classic symptom of something else? Alan 1 Quote Link to comment Share on other sites More sharing options...
mrelwood Posted July 3, 2021 Share Posted July 3, 2021 (edited) The role of the capacitor is only to provide power quicker than the battery pack can, for bumps and such. All the symptoms you describe are from something else completely. Did you have the mainboard tightly secured in its place when powering up the wheel? The gyroscope is located on the mainboard, so for the wheel to function the board must be properly installed. I would strongly suggest replacing the whole mainboard if you don’t have expert level experience in repairing EUCs, it’s your brother’s butt on the line after all. Edited July 3, 2021 by mrelwood 1 Quote Link to comment Share on other sites More sharing options...
Chriull Posted July 3, 2021 Share Posted July 3, 2021 7 hours ago, alapon77 said: He got it working again after a couple days wait, but had some red LED patterns (a fault code, I assume). He remembers which code? Although the 4? different codes do not tell too much:( 7 hours ago, alapon77 said: It only worked in Beginner mode AND it only goes a fee feet before powering off while riding (yikes!). I had the same thing with an ks16c, the predecessor. It felt like riding in soft mode but rode "normal" beside this until the fuse burnt at an incline. But inbetween motor driver/firmware changed a lot abd the 16s is a much stronger wheel. 7 hours ago, alapon77 said: took it to my workbench and examined the motherboard and found no damage or burns anywhere except the positive leg of the larger capacitor. You did check _all_ the mosfets?! They are "hidden' between the pcb and the aluminium. Can not really imagine how a fried mosfet could cause such a behaviour . But maybe a not 100% dead one? 8 hours ago, alapon77 said: https://photos.app.goo.gl/K1imWDH6Y2cRdnin9 Poor EUC Seems somehow like the gyro delivers wrong data, or the motor wires are mixed up (motor turning wrong way around) - but i'd assume you did not touch them So if the board and all connectors were properly fitted again and no (important) wires pinched the best way seems to go with a new board... 1 Quote Link to comment Share on other sites More sharing options...
alapon77 Posted July 5, 2021 Author Share Posted July 5, 2021 Thank you all very much for your responses! I apologize for just now replying. For some reason I was waiting on a notification when responses come up. Will review your responses more closely, so again, thank you! Happy Fourth! 🇺🇸 Quote Link to comment Share on other sites More sharing options...
alapon77 Posted July 20, 2021 Author Share Posted July 20, 2021 UPDATE: Just so this can be entered into the Knowledge Base, I've resolved the issue. I went ahead and replaced both electrolytic capacitors since the terminal legs were burned and severed. To my dismay, this did not resolve the issue so before telling my brother he's going to have to fork over more than $200 for a new board, I took one last look at the Horizontal Calibration function in the KS app. It didn't work last time, but wouldn't you know it... after a couple of attempts, the wheel finally went back to behaving like normal again. So there it is. Serendipitously, I'm glad I didn't discover that right off the bat because I wouldn't have discovered the two capacitors needing replacing. Thanks again for your tips with helping get this resolved! Alan 1 Quote Link to comment Share on other sites More sharing options...
mrelwood Posted July 21, 2021 Share Posted July 21, 2021 (edited) 12 hours ago, alapon77 said: I'm glad I didn't discover that right off the bat because I wouldn't have discovered the two capacitors needing replacing. Yes, you would’ve… The hunt wouldn’t have stopped there. The wheel would’ve still behaved like it did before, with soft balancing and cutting out while asking for power. But I’m glad to hear that the old faithful now works! Although, I would do a few stress tests before going on a ride myself. It is still possible that something else has also burned on the board, but which would only cause problems under a high load or high speed. Edited July 21, 2021 by mrelwood 1 Quote Link to comment Share on other sites More sharing options...
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