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What are the possible reasons for gimbal problem(s) ?

Discussion in 'Phantom 2 Vision + Help' started by Monkeyleg, May 15, 2015.

  1. Monkeyleg

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    I'm trying to find out all of the possible causes for a P2V+ having the "gimbal dance" problem. My camera works just fine, so here are issues I know of:

    1. faulty flex cable
    2. pitch shaft and potentiometer not correctly aligned on pitch circuit board
    3. loose pitch shaft
    4. burned out pitch board
    5. burned out tilt board

    What other possible causes are there that you're aware of?

    Thanks for any replies.
     
  2. Advexure

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    Not exactly answering your original question or adding anything more but I will comment that #2, is the most common problem we see amongst fluttering gimbals.
     
  3. Monkeyleg

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    Thanks. I had that and fixed it, but that didn't seem to solve the problem. I have a cable set on the way, including flex ribbon was well as the three cables to the gimbal base (or whatever that box is called). I'm just wondering how much money can be thrown down a hole before the problem is found.
     
  4. Monkeyleg

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    I found another post on this forum by a person who sounded like an authority on the subject. This is what he listed as the possible reasons for the gimbal dance:

    1. faulty flex cable
    2. pitch shaft and potentiometer not correctly aligned on pitch control board
    3. pitch potentiometer cracked or otherwise damaged, or yaw potentiometer in main control board
    4. loose and/or pitch shaft
    5. defective pitch control board
    6. defective control tilt board
    7. defective camera control board
    8. Bent parts (y bracket, etc).

    Is there anything else? Can the main control board for the gimbal be damage in a crash?
     
  5. RichWest

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    I think you're on the right path to a resolve, reading other posts with similar symptoms. Typical issues, after a crash, would be the flex-ribbon and/or gray cables to the gimbal.

    I think @hunch is your best resource for all things P2V+ gimbal issues. Dare I say an expert on the subject.
     
  6. jiminyfixit

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    I have been repairing these buggers for some time now and I'm constantly surprised at the causes for "gimbal dance". The best way to check for your particular problem is to have a perfect working test camera. Unfortunately, not everybody does. I have found the "pitch" circuit board to be the main offender. Not sure exactly what is wrong with it, (doesn't really matter), but I know when I put a good circuit board in, it works fine. I have over a dozen bad pitch boards. The "roll" circuit boards are the most robust. Every bad camera I have parted out has a good roll circuit board. The pitch shaft and motor are pretty robust, except for the obvious broken shaft. I did, however, recently replace a camera module and the "dance" went away. That was a new one for me. The other culprit is the "roll" motor separation from its bracket. If it is the slight bit loose, it will cause problems. If they are separated, inspect the condition of the black magnetic ring in the bracket. I have been able to use ones with slight scratches, but not with deep gouges. Fragments of this ring, getting into the windings, can also cause problems. Use an air hose to blow out particles and then use silly putty to pick up left over filings.
    I posted the complete procedure for re-attaching the motor to the bracket, but I can't place where I posted it. Having been a machinist, I came up with a mechanical means of firmly reattaching the motor, WITHOUT super glue or epoxy.

    The other culprit is the main circuit board where the "yaw" arm enters the upper housing. I have seen tiny chip resistors wiped off the board because the yaw arm dug into the cover plate, from a hard crash. You'll need to buy a used/damaged camera, and take a chance that the main circuit board is OK, IF you know that is the problem. Also, be very careful when "unlocking" any of the circuit board cable locks. Those tiny black plastic bars that when flipped down, secure the ribbon tightly in their connectors. I recently received a used camera that had EVERY lock removed with a screwdriver. :{

    AND, believe it or not, I have had, what looks to be good, ribbon cables that caused the problem. Here again, having a perfect, working camera, can solve these issues. BEWARE of some of the Chinese ribbon cables. They are counterfeit and the seller realizes, that when installed, and the camera still doesn't work, that you will think it is another component that is the culprit. I bought 10 from amethyst.e, tested 3, they didn't work, put the old one back in, and it worked fine. Most people won't go to the trouble of sending one ribbon cable back to China.

    Here is yet another problem with a fussy gimbal. The reason I came to this site today. Two perfectly good, working cameras started doing the same thing. Poor roll gimbal response. When I tilt the quad, the gimbal starts to work like a gimbal, but then it freezes and moves with the quad. Not a gimbal at this point. I believe it has something to do with my test quad, either internally, (Naza), or the wiring/connectors. I WILL find out what is wrong, TODAY.

    Hope this helps.

    Cheers,
    Jim
     
  7. h4v0c6

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    #7 h4v0c6, May 17, 2015
    Last edited: May 17, 2015
  8. jiminyfixit

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  9. Monkeyleg

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    Thanks for the detailed reply, Jim. I spent today going through the gimbal and making some changes. The ribbon wasn't ripped, but there were some funky areas where the previous owner (the one who crashed it) had tried to fix it. So I replaced the cable. I checked the gray cables going to the gimbal main board to make sure there were no breaks or broken connectors. I measured the pitch motor potentiometer, and it was right on at 3.2 ohms. I had already glued the pitch motor shaft into the cover after checking it for straightness. I measure the gap on the motor, and it was within .001" or .002" all the way around.

    I'm going to be getting a Vision + V3 on Tuesday. If they use the same boards, I'll try swapping out the pitch and roll boards and see if the problem goes away.

    h4v0c6, my gimbal dance is the typical one with the camera flopping around and then winding up pointing at the ground. There's no grinding noise as there is in your video. You camera is stable on the Z axis, which seems unusual.
     
  10. Monkeyleg

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    Wait. Jim, did you say that the pitch motor board is the most frequent culprit? Pitch being the up/down tilt of the camera?

    I confuse roll and pitch. The roll potentiometer and leveling seem to be the most common fixes on Youtube.
     
    #10 Monkeyleg, May 18, 2015
    Last edited: May 18, 2015
  11. h4v0c6

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    It's amazing how much hair you can loose over a loose screw! Tightened it up and I was back in business.
     
  12. jiminyfixit

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    Nicely done! I've done the same thing more times than I want to admit. In a big fat hurry to see if my repairs worked. :}
     
  13. jiminyfixit

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    Yes. The pitch motor circuit board seems to be the primary culprit. I was amazed after the first time I discovered this and repeated the fix many more times. Pitch circuit board issues include; semi twitchy, beeps with no function, unstable but no dancing, and hot motor with error message.The strange thing is that the "roll" circuit board gets small white marks on one of the chips. I was told they were "burn" marks, and were no good, but, found out from testing, they don't seem to alter the function of the board. Fortunately, I didn't throw them away. The pitch boards fail without any obvious "burn" marks. I'm not an electronics engineer, so I have no idea why they go bad. I watched the video of the guy who put the roll motor back in the bracket, adjusted the "horizon" and it worked. He was lucky. The only problem with that fix, is that it is temporary. One bump and it's "dancing" again. The motor needs a tight fit in the bracket to be reliable. Overall, I have found the sophisticated electronics in these cameras present challenges, as one circuit can adversely effect another, or remedy another.

    When I first got into repairing these camera, I went to Google to see diagrams of pitch, roll and yaw, to get it in my mind which was which. Nothing like a diagram to paint a mental picture.
     
  14. jiminyfixit

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    I have a customer sending me a V3 to compare components and possibly repair. We know the camera module is different, but not sure about the rest of the gimbal.

    I have developed a method of mechanically securing the roll motor to its bracket, WITHOUT super glue or epoxy. I can post if anybody is interested, as it is fairly detailed and exacting. In my younger days, I was a plastics cavity mold maker, (glorified machinist), and got quit comfortable working in .002 of an inch all day long, and learned many tricks of the trade, that I am just now benefiting from.

    Still curious if anybody has experienced the new problem I described in the above post. I replaced the Naza unit and I still get the same weird gimbal problem in two good cameras. VERY frustrating as it is my test quad. :{
     
  15. Jose0711

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    I recently purchased a P2V+ from a friend but noticed that the gimbal was giving an error at start up but the error disappeared later. The gimbal seemed to do fine once the P2 was flying but a little later it started to do some turning and twisting on its own. I'm new to the P2V+ and didn't notice that one of the lower screws on the back of the unit that connects the gimbal and camera to the P2 was missing its lower right screw. (I read in earlier posts that the bottom two screws are longer than the top screw.) Was wondering if the missing screw could cause the gimbal issues? Does anyone know where I can buy that particular screw for the gimbal? Thanks.
     
  16. jiminyfixit

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    Can you send a photo of exactly where you are missing a screw? I will put one in the mail for you gratis, as I have a LOT of extra screws. As far as the twisting and turning, it's difficult to know exactly what the problem is, because we don't know if the previous owner messed with the camera/gimbal. Check all screws and the set screw on the yaw arm to see if they are tight. Make sure the wiring connectors are firmly in their sockets.
     
  17. Jose0711

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    Thanks for the offer on the screw, but I did find the screw....luckily enough for me it was in the P2's carrying case. However, I would like to get the glitch in the gimbal fixed. Does anyone know how much it would cost to fix the camera/gimbal? I don't want to replace it though. I went to quad place in the local area and they told me that, for gimbals, they just replace them and don't fix them since only DJI has "special tools" that realigns the gimbal. Thanks.
     
  18. Jose0711

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    It looks like I missed a second missing screw. I couldn't find this one though. Does anyone know where I can get one of these screws? It belongs on the gimbal, I have attached a picture of the missing screw. Thanks.
    2015-05-21 18.36.52.jpg
     
  19. JJM

    JJM

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    Did you ever find a solution to this? I'm having a similar issue.
     
  20. burlbark

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    It could be the roll shaft motor or its a potentiometer value to far out of tolerance. Its a fairly easy and common fix that will require a complete disassemble and potentiometer replacement.

    Jeremy