7 out of 8 start

Discussion in 'Cinestar 8' started by Scott Strimple, Nov 10, 2013.

  1. Scott Strimple

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    Just pulled out the c8 for a shoot ... Had flown it less than a week ago... No issues.
    Today on set ... Calibrate compass... Power cycle and all 8 motors respond ... Wait for GPS light to flash ...Arm BL...
    And motor 7 no spin... Infact the other motors simply idle with no acceleration ( which clearly I would not want at this point anyhow)... Is there something simple I'm missing here? Havnt had time to pull the GPX file yet. Thanks
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    That's usually a sign that either (a) you don't have enough GPS satellites and a GPS lock, or (b) there's no microSD card in the Navigation Control board) or (c) there's a serious compass error and you need to calibrate.

    There may be other causes, but those are the ones that come to mind.

    Andy.
     
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  3. Steve Overstreet

    Steve Overstreet New Member

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    I have had that happen and found that by simply disconnecting power and reconnection it cleared the system and allowed me to fly. Some times it took 2 or three times. The best i can guess is that the system wasn't completely initialized before i attempted to start the motors.
     
  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Scott: are you using the Motor Safety Switch logic in MK Tool (whereby a physical switch on the Tx needs to be in the correct position to start?) Just going through some of the other possible causes.

    Also, were you flying in high humidity (that might result in one of the BL-Ctrl's MOSFETs having a problem)?

    With the copter powered up can you connect up MK Tool either via USB cable or via Xbee/Bluetooth, and see what the status of the MK avionics is? (NOTE: Be extremely careful if you leave the props on while doing this!)

    If you can see underneath the power distribution board, all the BL-Ctrl should be showing a green LED. Might be worth checking just in case you've lost a BL-Ctrl.

    Also, when you first power up, what do you hear in the way of chirps from the motors, and beeps from the Flight Control board, please?

    Sorry about the Spanish Inquisition. ("Noooobody expects the Spanish Inquisition....")

    Andy.
     
  5. Shaun Stanton

    Shaun Stanton Active Member

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    Sounds like a BL going out. Although its odd that it spins on initial power up. I had a BL failure little more than a year ago. Went to start up one day, and only 7 motors chirped. When I went to start it 7 motor spun, but the system is desiged not to let it go above idle if there is an issue like andy mentioned above, or there is a detected failure in the BL' system.

    My issue was that the BL went off line and was no longer being recognized by the FC. The solution was to reflow the solder on the addressing pads. Unfortunately that did not fix it so I ended up buying whole new PDB. Your sounds different though. The best thing to do is plug in the copter with LiPo and connect up copter tools to see if there is an error code on that BL.
     
  6. Brad Meier

    Brad Meier Active Member
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    Have a look at MKtools to see if that BL CNTL temp is way off. Ive have temp sensors go bad a few times.. won't start.
     
  7. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Steve:
    What may actually be happening is that the GPS hasn't achieved a 3D lock, or locked on to the minimum of satellites that you've got specified via MK Tool (typically 6). By power cycling the avionics, you're allowing for more time for the GPS to lock on.

    Certainly, if you don't have the minimum number and haven't got a fix it will allow a motor start, but you will not be able to throttle up.

    The last time I had this happen to me was even more bizarre. I was on a shoot out in the Alvord Desert in south eastern Oregon, right out in the boonies and on the Alvord Lake playa (more or less in the middle, so five miles of playa in every direction, with wall to wall sky view). The GPS unit acquired 16 satellites (normally I might get 8 - 12), but it could not get a 3D lock. I waited for 30 minutes. Tried again. Same result. I changed to a backup GPS unit. Same result. I even called Gary on voice to see if he could see anything unusual going on (I checked n3kl.org for solar weather using my iPhone).

    Then I tried one more time before having to tell the producer we weren't flying that day. And it worked.

    I checked GPX files for the previous two days. 16 satellites, got a lock within a minute. The days after, 16 satellites. Lock within a minute.

    I think little green men or the USA gub'mint might have been involved. :)

    Andy.
     
  8. Scott Strimple

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    Thanks guys! I tested the C8 again ... This time back at my studio. It all worked fine. The only thing I did different was to re rack the micro SD card in the navi board.
     
  9. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Scott: For what it's worth, I carefully insert the microSD in the NC board, and then put some white PVC tape around the edge, sticking it to the underside of the NC board, around the microSD card, and on to the top surface of the NC card. Don't put the tape around too tightly otherwise it starts the unlatching movement which is a Bad Thing!

    If I center punch the planet with the copter, I want to be able to find the flight data recorder! :)

    Andy
     
  10. Scott Strimple

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    Thx Andy I just started that very process.
     
  11. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Please keep us posted if you see any wackiness with the avionics, Scott.
    We may not all be flying the same ship, but I suspect we're all in the same boat. :)

    Andy.
     

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