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How to: Phantom 4 gimbal yaw and flex cable replacement
4059 14 2018-1-29
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djiuser_iGJqCoTNTQSa
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United States
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I wanted to shed some light on this subject, after searching and realizing the entire lack of material on this subject. I bought a P4 to fix the gimbal arm, which in itself should have been simple. There are videos that show you the entire step-by-step process. What they don’t show is the steps for what to do when things go wrong, so I will highlight what went wrong and what I did.
  


   
Yaw arm replacement tutorial:
  
Motor cap swap:
Gimbal flex cable replacement:
  


   
On the yaw arm, I got all the way to removing the yaw motor when I ran into issues. The screws are recessed, they’re small, they’re shallow, and they’re soft. I only use quality Craftsman or Snap-On tools, but these screws were beyond stubborn and ended up stripping. In hindsight, I would probably use a grinder and  a drill to  just grind down the arm until I could use a deemed to cut a notch in the screw and remove it, but I thought I could drill it out enough to remove it and use vice-grips. Nope, they’re recessed and the heads of the screws prevent drilling. They’re also too small to use a reverse thread on.

Yaw motor replacement section:

  
This resulted in me having to buy a replacement yaw motor. However, because the yaw motors are  calibrated, buying a new one may causes issues where your gimbal will yaw back and forth or just point the wrong direction. This is not a guarantee that all new motors will do this, as some will work just fine. There are two options for this issue: have a DJI authorized center calibrate it, or swap the motor cap. I chose the latter, because it’s free. Also, the best part of this method is that it means you don't have to care if the motor you buy is the old or new style yaw motor (yes, there are two yaw motor caps and their mounting plates are different. The base of the motor is the same). See the second YouTube link for how to do it. If you do the former, you can ignore this next section and just install the motor. Alternatively, you can just install it and hope for the best, but that means disassembly if it doesn't work. The following took me about 8 minutes total, having never done it before and creating my own method as I went.
I made a few revisions to the method in the video: when pressing out the motor pin, the initial blow takes the most force and you can damage the cap by constantly banging it. Instead, I used a bench vise, a 7mm socket, and a T5 Torx bit. Putting the 7mm on the bottom of the motor and the torx bit on the pin allows you to efficiently press out the pin just the right amount. When pressing it back in, place the back of the Motor o on the vice clamp and place a 7mm docket on the front bearing. Verify that your socket is pressing against the outer rim of the bearing and not on the seal. I do it this way because tapping it from the bottom with a hammer can press out the upper bearing. Be aware that this takes almost no force to reseat the pin. Once the pin is reseated, just stick the motor cap on top, put the 7mm socket on top of the motor cap, the pin against the vise, and press the cap in until the pin is flush with the top of the motor cap. That’s it, you’re done.
I bought the yaw motor on Amazon, but there are some "new" ones on eBay. If they come to your door with threadlock in the threads, this means they're used. I have no idea if the ones on Amazon are used,so make sure to check the threads of the motor cap and the base. I also bought the DJI Phantom 4 screw kit on Amazon. However, you can probably buy one of those 500 piece laptop screw kits, instead, as the DJI screw set only has 4 motor screws. This means that if you need to replace two motors, or you lose more than 4 screws, you get to spend another $13 on a second screw kit. The motor screws for both the yaw and the roll motor are M2 x 2.8mm, but a M2 x 3mm might be fine, just verify that you don't bottom out the screw.

Flex cable section:
  

If you have to replace the cable, mine tore, I ended up getting the one from Fstop Lab because it included the yaw arm and the flex cable. It's on Amazon. Because I was replacing the yaw arm, this became tremendously simple. Even if you are not, the third video shows how to do it. The biggest issues I ran into was that I accidently mounted the roll arm upside down, which will cause some very severe gimbal motor overload issues. Also, it's a pain to stick each connector in and bending the new flex cable requires extreme delicacy, because it will tear if you are not careful.
Tips:
  • Each connector on the flex cable itself has a white line that indicates how far you need to insert it. Ironically, not all of them insert the same depth. Some will insert such that the white line is completely inside the board connector, others will just reach the edge of the connector. A good rule of thumb is that your cable's white line should, at a minimum, be even with the end of the female connector portion on the board. If it's not, you need to push it in more. I also tried tweezers for the tight spots, but that was useless.
  • Take pictures of how the cable was oriented if you're prone to forgetting.
  • Start at the camera's board itself. Work away from there, sticking on each section at a time.
  • Plug in each connector and route the cable before you start peeling off the adhesive cover. This will allow you to bend the cable without compromising the adhesive.
  • Keep the old cable next to you as a template for how each section was bent.
  • Push the cable as far away from the camera as possible.  The tolerances are VERY tight, and the camera touching the flex cable will cause gimbal errors
  • Firmly press the adhesive down, to prevent it from peeling up.

And, that's all I can think of, for now. Feel free to ask questions.

2018-1-29
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Mike Davies
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Flight distance : 1288885 ft
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2018-5-6
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Mike Davies
lvl.3
Flight distance : 1288885 ft
United States
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Hi Ted, is this what you meant by scratches in the sensors???
2018-5-6
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Mike Davies
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Mike Davies Posted at 2018-5-6 08:23
Hi Ted, is this what you meant by scratches in the sensors???[view_image]

2018-5-6
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djiuser_iGJqCoTNTQSa
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Yes, that looks like damage to the sensor.
2018-5-6
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Mike Davies
lvl.3
Flight distance : 1288885 ft
United States
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"DO NOT BUY YAW MOTOR PARTS OFF OF AN EBAYER FROM MONTCLAIR, CALIFORNIA"...."THEY HAVE MULTIPLE DIFFERENT NAMES ON EBAY"THEY ARE ADVERTISED AS NEW BUT I RECEIVED ONE TODAY THAT HAD ONE OF THE SENSORS MISSING.
2018-5-9
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Mike Davies
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United States
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Mike Davies Posted at 2018-5-9 08:50
"DO NOT BUY YAW MOTOR PARTS OFF OF AN EBAYER FROM MONTCLAIR, CALIFORNIA"...."THEY HAVE MULTIPLE DIFFERENT NAMES ON EBAY"THEY ARE ADVERTISED AS NEW BUT I RECEIVED ONE TODAY THAT HAD ONE OF THE SENSORS MISSING.

ALSO, THEY ADVERTISE AS "NEW" BUT DOWN IN THE DESCRIPTION IT SAYS "95% NEW"... BIG BUMMER!
2018-5-9
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part-time
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Mike Davies Posted at 2018-5-9 08:52
ALSO, THEY ADVERTISE AS "NEW" BUT DOWN IN THE DESCRIPTION IT SAYS "95% NEW"... BIG BUMMER!

Thanks for the advice!
2018-5-9
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part-time
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Great information.   I Love this Forum...      Thanks for your time and dedication dude.....
2018-5-9
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djiuser_iGJqCoTNTQSa
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Hence my warning: I had a feeling that they were pulling motors off used drones without ever inspecting them.
2018-5-9
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Mike Davies
lvl.3
Flight distance : 1288885 ft
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Buying P4P Yaw motor from a new U.S. source that seems to be reputable, I will keep the forum updated on my results.
2018-5-16
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Mike Davies
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part-time Posted at 2018-5-9 10:29
Thanks for the advice!

No problem
2018-5-16
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Funbobby
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Flight distance : 76811 ft
Canada
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Thanks for all the info! I first tried just installing the new yaw motor, which didn't work.  The camera still just wanders back and forth randomly.  So I took it all apart again and changed back to the old motor base(rotor) with the new yaw motor stator.  It still didn't work, possibly because there was a small chunk of the magnetic material in the rotor missing. Likely due to contacting the sensor during impact.   Now the big question is, how do I calibrate the new yaw motor to be compatible with the existing gimbal electronics?
2019-2-6
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Just_nick
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Funbobby Posted at 2-6 21:07
Thanks for all the info! I first tried just installing the new yaw motor, which didn't work.  The camera still just wanders back and forth randomly.  So I took it all apart again and changed back to the old motor base(rotor) with the new yaw motor stator.  It still didn't work, possibly because there was a small chunk of the magnetic material in the rotor missing. Likely due to contacting the sensor during impact.   Now the big question is, how do I calibrate the new yaw motor to be compatible with the existing gimbal electronics?

You need to use the base from the new motor and the cap from the original motor. The purpose is that you get new sensors, and the sensors are irrelevant because they are always positioned the same way. It's the cap that is what the board is calibrated to, which is why you use the new base and old cap.
If it doesn't work like that, your new motor may be defective.
2019-2-8
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onehungrydog
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Flight distance : 610164 ft
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Hey guys, I know I'm a little late to the show here, but it seems the best place to start as I have not seen this specific problem.

I had a little accident where from what I gather, the yaw motor was ripped apart. From what I am guessing, it looks like a little clip holding it together was broken. I can actually snap it back into place and even flew with it like that, but now I'm getting "gimbal overload" warnings and obviously I want to fix it anyways.

I do have DJI refresh and have used it with good results, but I am guessing that this repair might be done for under $100 and would like to save the refresh for something more catastrophic.;) It looks like I just need to purchase the yaw motor?Also, I don't own a vice but would probably pick one up if there is no other way.

Thanks for any and all input.
2019-6-15
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