How to test ESC board? (Q500 4K)

Discussion in 'Help' started by Jay K MacGill, May 12, 2019.

  1. Jay K MacGill

    Jay K MacGill Member

    May 12, 2019
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    Hey guys, I crashed my q500 4k (long hard fall onto concrete). GUI shows 2 motors failed on startup, not sure how to determine if it's the motors that failed or the ECS boards.

    I've seen some esc testing videos where continuity was probed for on the power in and power out (to motor) terminals of the esc board.

    I'd like to determine what's failed before ordering replacement motors or esc boards. I took a pic of of the queationable boards, but no apparent defects/damage seen. Let me know if anything sticks out in the pic that I may have missed.
     

    Attached Files:

  2. Jay K MacGill

    Jay K MacGill Member

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    Motors dont appear to have visible damage that would be obvious defects. They both feel fine when turning.
     
  3. WTFDproject

    WTFDproject Active Member
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    All three pictures appear to be the ESC for motor #2. The pictures only show one side of the board. Can you upload a picture from the other side?

    I can see the ESC connector is unplugged. Did you unplug it for the picture, or was it unplugged from the event?

    Have you replaced the air-frame? Or had the ESCs out for any reason? IF so, did you re-do motor re-assignment?

    Motor reassignment might help anyway. even if nothing has been disconnected.
     
  4. Jay K MacGill

    Jay K MacGill Member

    May 12, 2019
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    #4 Jay K MacGill, May 12, 2019
    Last edited: May 12, 2019
    Great questions, see clarifications below.

    -These were pics from motor 2, I haven't photographed the other problematic one yet. (Motor 3).

    - Both the remaining functional motors (GUI checked/passed) and problematic motors physically turn and feel the same. No noticable weird sounds, grinds or resistence outside normal.

    - I'll get the underside pics of motor 2's board when I get back home (hour ish). Will get motor 3's uploaded as well.

    - I unplugged everything to access the board/photograph it. All wires/plugs were plugged in as they came from factory just before these pics were taken.

    - No previous modiciations to motors or frame... all OEM.

    - Hard crash, failed to initialize, GUI speeds tests showed errors in 2 & 3.
     
  5. Jay K MacGill

    Jay K MacGill Member

    May 12, 2019
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    Underside Motor 2 board.
     

    Attached Files:

  6. WTFDproject

    WTFDproject Active Member
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    I'm thinking if the crash was not hard enough to break the air frame, it is not likely to have jarred the ESC chips. Can you upload the flightlog directory from the ST10 SD Card? I would like to look at the data to see if the ESCs failed while still in flight.
    How much can you tell me about what caused the crash? I.e.., was it a "fall out of the sky" scenario?

    Look at the circled item in the photo. It looks like a blown mosfet. See if the residue is melted plastic or just some stray black sealant. marked.jpg
     
  7. Jay K MacGill

    Jay K MacGill Member

    May 12, 2019
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    Motor 3 board, top
     

    Attached Files:

  8. Jay K MacGill

    Jay K MacGill Member

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    Motor 3 board, underside
     

    Attached Files:

  9. Jay K MacGill

    Jay K MacGill Member

    May 12, 2019
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    Got to close to a palm tree and impacted the big leaf / definitely my fault.

    Pics attached of that particularly fet, looks just like a dash of stray sealant from the nearby component with a gob of the same sealant. Not melted looking. Best I could with pics focused on that spot attached.

    I'll get the telemetry ready tomorrow.
     

    Attached Files:

  10. WTFDproject

    WTFDproject Active Member
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    I see no other obvious problems with either ESC. The telemetry MIGHT give us a clue.

    Did you try to do motor/esc ASSIGNMENT in the GUI, or just motor test?

    The larger chip with the blue paint marker is the main chip on the esc. It sequences the six mosfets to produce the pattern needed by the motor. It is a common failure point, but never shows visible damage. Damage, if visible at all, is normally only visible on the mosfets. That leads many to change out the mosfets, just to have them blow again.

    The main question is "Why two". First thing is to think of it as something common to both, but haven't figured out what it might be. Maybe the two rear props happened to hit at exactly the same time?

    It might be worth moving one of the front escs to a rear motor, and then do a motor test to see if it will run. (front and rear escs are identical except the red/white led wire color). If you move esc#1 to esc#2, you will still have to tell the GUI to start #1. It won't know you moved the esc, and it's still coded for the #1 position.
     
  11. Jay K MacGill

    Jay K MacGill Member

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    Will look into this tomorrow. Great info, thanks.
     
  12. Jay K MacGill

    Jay K MacGill Member

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    I had done the ESC ID Assignment (enable testing, props off etc.).

    1) front left good
    2) rear left good
    3) I turn it, it doesn't sense and fails.
    4) never make it to 4...

    Error says 2 and 3 failed... but the picture on screen shows front right and rear right as red cicles/bad.

    Is that the correct position for those numbered motors? Had bought this bird used, prev. oner mentioned some crashes..
     
  13. WTFDproject

    WTFDproject Active Member
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    I had some bad ESCs on a Q500 that went into salt water. I remember the GUI had problems knowing which ESC was which. When the bad ESCs were replaced and assigned, everything went back normal.

    Another possibility is that the numbers reported in the error messages are a "legacy failure". The Q500 GUI is the direct descendant of the 350QX GUI. On the 350QX, the motors were numbered clockwise, meaning 2 and 3 were the right side motors, instead of 3 and 4. I wonder if someone missed the numbering in the error message when upgrading the program, and left a confusion factor?

    The fact that 1 and 2 assigned normally hints that the real culprit is either 3, 4 or both. The fact that motors 1 and 4 ran when you did the GUI run test suggests 4 may also be good. None is certain, considering the discrepancy in what the GUI is reporting.
    I can't remember if the telemetry data will specify which motors failed, but maybe so. The good thing is that it is becoming fairly clear that the issue is ESCs. Not the easiest thing to replace, but at least it can be done at home, and not have to send to a repair center.
    Best guess at the moment is two new ESCs, but maybe only one, and maybe three. (I doubt 3). Right now the only esc that is NOT showing bad anywhere is #1.
     
  14. Jay K MacGill

    Jay K MacGill Member

    May 12, 2019
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    That makes sense if they're numbered clockwise. The order of which the GUI had me physically turn the motors went 1) front left; 2) rear left; 3) rear right (fail)...I assumed that was 1/2/3/4 etc, but maybe not.

    I'll have time tonight after work to mess with it. I don't mind at home soldering/maintenance.Just want to make the most of my time and money and not run in circles
     
  15. WTFDproject

    WTFDproject Active Member
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    That is the correct order for the Q500.
    I'm old. I go the way of spending time first, then money as last option. If you can swap ESCs around you may be able to narrow down how many new ESCs you have to find. When swapping around, remember you have to tell click the Gui spot for the ESCs original location to get it to respond.
     
  16. Jay K MacGill

    Jay K MacGill Member

    May 12, 2019
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    I'm considering snipping the wires needing and putting butt connectors on to avoid soldering. THis way I can swap around the parts needed with minimal soldering? Is there any disadvantage to this assuming I can make the connectors fit? If so I may just move the parts around and use butt connectors until I find out what's what and then solder the final order it needs to be.
     
  17. Jay K MacGill

    Jay K MacGill Member

    May 12, 2019
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    If you're free later I'd love to get you on the phone and pick your brain for a minute before I crack open the bird and move stuff around. Feel free to PM me with a time convenient for you.
     
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