alcatraz Posted July 25, 2022 Share Posted July 25, 2022 Hey Had a low speed cutoff on the msx84 and before I open it up I'd just like to ask what to check. Mosfets? It won't power on anymore. It was a warm day (32C?) but there weren't any alarms or tilt-back. The wheel had done 9000km already and this is the first ever issue. It had been trolleyed for 20min, and then I got on it to leave. Luckily I was checking the map so I was going slow at the time. Unluckily my phone got ejected, crap! I wonder if there was a fan malfunction and the thing somehow overheated. Doesn't the msx84 tilt-back or beep when that happens? The argument against overheating is that on a harder ride with climbing I never go over like 45C so how the hell would it overheat at low speed on a flat surface? Last time I had the wheel open was a week ago when I fixed a puncture. I saw signs of some contaminants around the trolley handle area but the board area has been clean. I haven't ridden in the rain in a couple of weeks. It's a very dry area I live in. I wonder if I perhaps pinched a cable or something? Quote Link to comment Share on other sites More sharing options...
alcatraz Posted July 26, 2022 Author Share Posted July 26, 2022 A few more details. The packs are ok and stable at 79 volts after one night. That's the same voltage they had when it cutoff. I disconnected them this morning and measured them. I could smell something "electric" when laying the wheel down, but after opening the side cover I didn't notice anything burnt. At first glance the board looks clean. I tried leaving the packs disconnected for a few minutes and reconnecting. The wheel is still dead. There was a spark when reconnecting so the caps were charging up. When disconnecting the second time I measured the caps to see their voltage. One was 40v and the othet 25v and dropping fast. I couldn't even count to 20 before they were completely discharged (on their own). I didn't press the power button or anything. So that's a clue. Also the motor spins perfectly free. Any ideas? Thanks! Quote Link to comment Share on other sites More sharing options...
alcatraz Posted July 26, 2022 Author Share Posted July 26, 2022 I contacted Gotway and they've offered to have a look at the board and perhaps fix it. I might send it to them. I was however hoping for someone to point out a simple measurement I can do with my multimeter to rule out common issues with mosfets or whatever else they've encountered. Quote Link to comment Share on other sites More sharing options...
Tawpie Posted July 26, 2022 Share Posted July 26, 2022 Without a schematic, I think you've eliminated the easily discovered problem of a MOSFET short (the motor spins freely). Your capacitor test is perhaps telling, they usually hold charge for quite a bit longer than a 20 count. I have no other ideas for you! 1 Quote Link to comment Share on other sites More sharing options...
EMA Posted July 26, 2022 Share Posted July 26, 2022 20 minutes ago, alcatraz said: I contacted Gotway and they've offered to have a look at the board and perhaps fix it. I might send it to them. I was however hoping for someone to point out a simple measurement I can do with my multimeter to rule out common issues with mosfets or whatever else they've encountered. measure volts on capacitors with the battery connected, be very carefull doing it. 1 Quote Link to comment Share on other sites More sharing options...
alcatraz Posted July 27, 2022 Author Share Posted July 27, 2022 Thanks a bunch for the confirmation and suggestion. Really appreciate it. Sending the board in will take a week at least for me to even take it out out. Two of the motor connectors are soldered to the board. It's going to be tricky to take them off without pulling the board's female banana socket off too. Two-man operation. I got the wheel with 5000km and the previous owner must have thought that to be a good idea, to solder two of them? It rode fine for 4000km after I received it so I don't think that caused the problem. Quote Link to comment Share on other sites More sharing options...
alcatraz Posted July 27, 2022 Author Share Posted July 27, 2022 15 hours ago, EMA said: measure volts on capacitors with the battery connected, be very carefull doing it. There are three capacitors. Two big and one small. They're all the battery voltage of 79.0v. I checked again and as soon as I disconnect the batteries from the board the voltage plumets. Unlike my tesla which seems to store the charge longer. Have I got a short to ground or something? Quote Link to comment Share on other sites More sharing options...
EMA Posted July 27, 2022 Share Posted July 27, 2022 4 hours ago, alcatraz said: There are three capacitors. Two big and one small. They're all the battery voltage of 79.0v. I checked again and as soon as I disconnect the batteries from the board the voltage plumets. Unlike my tesla which seems to store the charge longer. Have I got a short to ground or something? the capacitors should store the energy like your tesla, there's something wrong somewhere 1 Quote Link to comment Share on other sites More sharing options...
EMA Posted July 27, 2022 Share Posted July 27, 2022 i had a monster3 defective board that act like yours some times ago, but it was defective since the beginning, it never works 1 Quote Link to comment Share on other sites More sharing options...
alcatraz Posted July 27, 2022 Author Share Posted July 27, 2022 Thanks. 5 minutes ago, EMA said: i had a monster3 defective board that act like yours some times ago, but it was defective since the beginning, it never works Board swap fixed it? Did it malfunction again later? Quote Link to comment Share on other sites More sharing options...
EMA Posted July 27, 2022 Share Posted July 27, 2022 1 minute ago, alcatraz said: Thanks. Board swap fixed it? Did it malfunction again later? yes, swapped the board and everything was fine, i sold the wheel but it still run 1 Quote Link to comment Share on other sites More sharing options...
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