Motor fails in flight

Discussion in 'Cinestar 8' started by Michael Koff, Apr 22, 2014.

  1. Michael Koff

    Michael Koff Member

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    been flying almost daily, no issues, motor failed in flight today, on first flight about 2 minutes in. I recovered and landed, pulled the boom and motor off, replaced motor and still not working....it jitters and tries to turn, but never successfully rotates....not sure where to go from here as far as troubleshooting and replacing the needed components. I GREATLY appreciate any help from the more experienced users...
    Thanks.
     
  2. Steve Maller

    Steve Maller UAV Grief Counselor

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    Glad you got her back in one piece. Three cheers for redundancy!
    As far as your copter goes, it's quite likely that the problem is with your ESC or brushless controller, not the motor itself. What kind of copter do you have, and with what electronics package?
    If it's a Mikrokopter-based ship, the MK-Tool software should give you a good indication of what's wrong.
     
  3. Michael Koff

    Michael Koff Member

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    Hi Steve,
    Its a Cinestar 8, with MK electronics. Embarassed to have to ask, but whats the process of finding the issue via MK-tool? I've got the program installed on PC, just have never used it (never have had any issues)...
     
  4. Steve Maller

    Steve Maller UAV Grief Counselor

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    Well, this is a perfect opportunity to familiarize yourself with it.
    I'd suggest purchasing Andy Johnson-Laird's excellent DVD (available for download, too) about MK_TOOL: http://rathergoodguides.com/dvds/mk-tool.html
    If you have a 4S (16V) system, then it's likely that Quadrocopter can repair your power distribution board. If you have a newer "heavy lift" system with the 6S power board, that's not repairable, AFAIK.
    But you really need to invest some time in learning about the copter. There's a wealth of information available if you know how/where to look.
     
  5. Michael Koff

    Michael Koff Member

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    Steve,
    Its 4S, I will order the DVD tonight...hate having to send it back, QC just did a bunch of stuff to it and it took 6 weeks longer than they said it would. This is why I'm trying to locate the issue, order the part, and hopefully replace myself...
     
  6. Steve Maller

    Steve Maller UAV Grief Counselor

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  7. Michael Koff

    Michael Koff Member

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    Thanks Steve,
    Its just the question on if thats the problem...I will plug into MKtool and see if anything pops up, but until I watch these videos, I wouldn't even know where to look...all I know at this point is its not the motor itself. Kind of strikes down the confidence level, as there was no warning...not sure if there is a way to test all BL modules before flight...? I'm sure I'll gain a plethora of knowledge from the vids.
     
  8. Dan Walker

    Dan Walker Member

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    Michael, there's plenty of info on the MK web site describing how to use the MKUSB - though you should definitely get the videos!
    So once you plug the MKUSB to the Flight Control and open up MKTool - then MKTool should give you a series of green lights (bottom center) unless there's an error - then you'll see one or more red lights.
     
  9. Ozkan Erden

    Ozkan Erden Distributor

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    Michael:

    * On your telemetry screen of the transmitter, do you get any error like "BL Missing?".
    * I believe one of your BL Controller gone bad. That happens. If that's the issue, desoldering them can be kind of pain if you don't have any soldering experience.

    To understand if there is a problem with a BL Ctrl, power your copter and check the lights of each BL Ctrls.
     
  10. Shaun Stanton

    Shaun Stanton Active Member

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    In order to test the copter through K-tools. You need to plug in the copter to your PC using a FTDI chip called the MK-USB. It blugs into the Debug port on the NAV board using a 10 pin ribbon cable. Turn on the copter and open Kopter tools. Once this is done you should get a status screen that gives you a box for the FC, NAV GPS and BL controllers. If the system detects a problem it will give you a BL error and the Box will be red. Status screen that will give you an error code for the BL. My guess is that it is a faulty BL, probably a bad MOSFET and the motor is not getting a good signal from of the phases. Its jittering probably because its only getting 2/3's of the three phase AC signal..

    De-soldering them without a real good De-solderer iron is almost impossible and you risk de-laminating the board. You most likely will need to send it to QC or find a shop that has the proper equipment to do it.
     
  11. Michael Koff

    Michael Koff Member

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    Thanks for all the input. I have hooked up the copter to Kopter tool, and the middle window shows no problems or errors, everything is green with status good.
    As far as "To understand if there is a problem with a BL Ctrl, power your copter and check the lights of each BL Ctrls.:, I believe where each motor lead plugs into board there is a green light...I assume this is what Ozkan is explaining? If so, there is a green light on the lead that failed...
    Also worth mentioning, when I start up copter at this point, and the failed motor stutters and never gets going, I'm unable to throttle up...as I push throttle up, the 7 working motors immediately come down to idle...not sure if this is useful...
    Also, what program do you all use to read the GPX files? I pulled the card to look at the log (also my first time doing this), but the PC won't open the file...
    Thanks y'all.
     
  12. Dan Walker

    Dan Walker Member

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    Being a newbie at this stuff myself, I might break out the magnifying glass and check the failed ESC for bad solder joins on the motor pigtails. A small crack in the solder join could lead to a failure of the motor to fully spin up, while still allowing the i2c bus to report no errors.
     
  13. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Michael: Do a Google search for MK_GPXTOOL for reading the GPX files. As Steve pointed out, I have made a video of how to use MK_GPXTOOL (as well as MK Tool).

    You may have an interlock set that prevents the motors from throttling up unless you have a good GPS fix (blue light blinking on GPS board top surface).

    Have you removed the props from all the motors -- you *really* don't want to be messing with motor starts, BL-Ctrls etc. with the props on as it is extremely dangerous to work near those rotating steak knives.

    Andy
     
  14. Steve Maller

    Steve Maller UAV Grief Counselor

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  15. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    If I'm not mistaken, the BL-Ctrls actually use electrical data from the motors as part of their control process. So the BL-Ctrl's run a self-test and then chirp the motors to say everything is OK.

    Michael: during that self-test do you hear all the motors chirp (and twitch slightly)?

    Andy.
     
  16. Michael Koff

    Michael Koff Member

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    Yes, I used common sense and took the props off :p
    I have every intention of downloading the videos...in fact I should have internet long enough to start the download tonight...
     
  17. Michael Koff

    Michael Koff Member

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    hmmm, thats a good question Andy...I know 7 of 8 chirped, but I need to plug it back into confirm whether or not the failed motor chirps. Unfortunately I will not be in front of it for a couple days as I'm on location in BFE...may phone in the wife (who is scared as hell to even touch the thing) to have her plug it in to see if it chirps...
     
  18. Shaun Stanton

    Shaun Stanton Active Member

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    That's a safety feature with MK. That means the system is detecting an fault, for some reason it is failing to report it to K-tools. When there is failed BL or other critical system the FC will not let you throttle up for safety.

    Do you have a Micro SD card in your Nav board? If so upload a the latest GPX file that was during the flight where it failed. Might find the culprit. There will be a date on the file.
     
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  19. Michael Koff

    Michael Koff Member

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    So last week after hearing your feedback, I sent the PDB back to QC for diagnosis. Turns out ESC #4 and ESC #6 were both bad, with "white smoke" coming from ESC #7. At their recommendation, I replaced the whole PDB. Just got it back and put copter back together...now I have a small issue again I'm trying to figure out...on startup, the copter spins left...as if I have the rudder full stick. After I let it spin for bout 20-30 seconds, the motors idle down a little and it comes to a stop. This is all without me touching the radio. Once I spool up motors, it spins again. When bringing motors up, I hear/see the motor speed changes for yaw and pitch, and right rudder, but when I hit left rudder, there is no audible difference in motor speeds. I'm hoping this is an easy fix?? I checked all motor leads, I have everything plugged in correctly, assuming QC didn't mistake any of their color-coded ESC leads on the PDB. Also, maybe worth noting, when plugging in the battery, the motors arm with one out of order...upon plugging in battery, they arm:
    motor 1
    motor 7
    motor 8
    motor 6, 5, 4, 3, 2, 1
    Seems like 7 and 8 are switched, but I don't know if this maters, and I am positive the motors are connected to the right PDB leads.

    Any ideas on how to get this baby flying again?
     
  20. Dave King

    Dave King Well-Known Member

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    Michael the odd motors should be spinning clock wise and the even motors should be spinning counter clockwise. If you have any motors not spinning correctly reverse the blue and red wires if you color coded them. Once you connect back up try it again with the motor test one at a time until you know for sure that its good. Also I would check your servo trims in your radio. If your using a MX20 go to servo display and make sure that channels 1 through 4 are 0. Adjust the little rocker switches on the radio until they show 0. I always look at my servo display menu as the last check before I start the copter. If these trims are off your throttle can be higher at idle, your yaw could be off, as good be your roll and forward/back controls. It's imperative that the trims are zero'd out or your copter can take off in all sorts of directions and go out of control as soon as it gets off the ground. As Andy Johnson Laird once said "Ask me how I know".
     

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