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  1. F

    Sempu wanted

    No problem there. I'm the one who pointed out that the Sempu may overload the 10V supply from a CA and should instead be powered from a higher voltage, like full battery if that is within the 60V rating. The failure was "operator error".
  2. F

    Sempu wanted

    My fault. I foolishly coasted down our hill with my battery disconnect open. When I engaged regen braking (which I love!), the voltage went through the roof. The controller survived but the Sempu did not. I'll avoid that maneuver in the future, but will also add a resistor and TVS to the...
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    Sempu wanted

    Thanks! I've got one on order now. I'm glad that they are still available. This type of sensor seems like an endangered species, so if it works like the original one, I'll buy a spare.
  4. F

    Sempu wanted

    My Sempu is toast, and I'd like to replace it with same if I can find one. It is the T2 model, for 68mm bottom bracket, width = 115 mm, 1.37" - 24 thread. Anybody got one kicking around? Thanks!
  5. F

    Denver commuter e-bike

    A sad end to a good project. Take heart. Don't give up! Once you get past this problem, it will be a great bike. This same Sempu BB, bought from Grin a couple months ago is working well for me, and seems like the best torque sensor going right now. Again, if Grin does not want your broken...
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    Denver commuter e-bike

    Well, game over I guess, unless you want to open the CA3 and try to troubleshoot/fix it. There are several hints and suggestions for doing that, mostly buried in the long "Cycle Analyst V3 Preview..." thread. There must be a connection between the Sempu failing and the CA3 doing so a bit...
  7. F

    Denver commuter e-bike

    Well, time for troubleshooting, huh? One simple thing to try is to unplug the Sempu PAS connector - it is powered by the 10V rail of the CA3. Maybe the failed Sempu is dragging down the 10V supply. Unplug it and see if the CA3 comes to life. Pure guesswork, but easy to try. Assuming that...
  8. F

    Denver commuter e-bike

    Thanks. I was curious in part whether the Sempu BB had broken mechanically (broken spindle = crashed bike, usually). I'm also interested in the Sempu electronics. Awhile back I posted some measurements and asked if anyone knows how they work. No response to that, although I bet someone in...
  9. F

    Denver commuter e-bike

    You broke a new Sempu? How? What broke?
  10. F

    Cycle Analyst V3 preview and first beta release

    Well, that's some good troubleshooting. The display reading B+ minus 12V is an especially good clue. I suspect that your connector short blew out a board trace or via among the the grounds, so now "ground" is not all at the same voltage. Try measuring resistance among the various "G" pads...
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    Cycle Analyst V3 preview and first beta release

    Hard to say what is going on, but it sounds like more damage has been done since you posted video of the splash screen coming on. It may be that the 5 Volt regulator is blown now, and maybe even the microcontroller. The micro is about the only part you can't fix yourself. If you can see signs...
  12. F

    Cycle Analyst V3 preview and first beta release

    We need to clarify how to do this test. The LED backlight for the display is connected between LED+ and LED- and has a normal operating voltage of about 3 Volts, so if you applied 12 VDC between those pins, it would just make the LED light up, and maybe damage it. Justin's original...
  13. F

    Cycle Analyst V3 preview and first beta release

    Yes, that's right, thanks for the correction. I edited it above. And about your question on the board coating, yes, that feels like a silicone based conformal coating. It would be nice to coat over your repair, but I don't know what kind to use or where to get it. I left it open on mine, but...
  14. F

    Cycle Analyst V3 preview and first beta release

    Trash can?! You wouldn't throw this little jewel in the trash, would you? You can fix it. It probably has a damaged regulator FET, Q1. See posts above for how to test and replace. There may be other damage, too. The brief turn on, then off may be the polyswitch re-settable fuse acting (the...
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    Cycle Analyst V3 preview and first beta release

    Good going! That's the hard part. Clean the old solder off the pads with desolder braid so the new part will lie flat, and clean the whole area with a Q tip + alcohol. You want a little fresh solder + flux on the big pad. Put the new part on there and heat the tab until the solder reflows...
  16. F

    Cycle Analyst V3 preview and first beta release

    I'm the new guy here, and I think it would be good to let Justin and the other experts weigh in before we arrive at the best way to power the Sempu bottom bracket. But offhand, I'd say don't tap your battery pack, except maybe as a temporary measure until you get something better going. DC/DC...
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    Cycle Analyst V3 preview and first beta release

    I can answer this because I repaired one with this problem. The Zener diode Z1 should not get hot. If it does, it is likely because the regulator FET Q1 is damaged. Measure resistance between the two legs of Q1. Should be 150 kOhm - if it is a lot less than that it is because the gate of Q1...
  18. F

    Cycle Analyst V3 preview and first beta release

    Hello Justin and all, I measured the Sempu current draw on the bench with a variable lab power supply; voltage and current measured with Fluke 27 DVMs. I'm pretty sure the unit is healthy and that this is typical operation. It goes to sleep after 10 minutes and wakes up with slight rotation of...
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    Cycle Analyst V3 preview and first beta release

    This is my first post, but I've been reading and learning here for awhile. Real good stuff here! I'm just a basement tinkerer here in bike-friendly Fairfax, Ca. I've been building up and riding a rear wheel drive conversion: old 1980's Jamis frame, a used ebikekit hub motor, 36V battery pack...
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