Who's up for a challenge? Diagnosing P4P v2 gimbal issues

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Hello folks.

Here's the good news: I got some great shots.

The bad news: My P4P v2 got pretty beaten up.

This challenge is for those with some experience diagnosing and repairing these drones and, specifically, the gimbals.

I've got it back to full flight capabilities with the exception of a rear sensor that needs to shift slightly to sit properly in its opening.

The challenge now is to diagnose the gimbal problem(s) based on the following symptoms:
  • The gimbal yaw arm is bent (see the images). That's an easy one (although getting a replacement that's been manufactured with the slightest quality control may not be so easy). BUT, weirdly enough, the camera is tracking the horizon and the video is smooth (see the test flight video).
  • The gimbal autocalibration thinks it's calibrating successfully, however it only pitches the camera up and down then sits there for the rest of the calibration without moving the roll and yaw motors.
  • When fired up, the gimbal occasionally makes an unhappy sound, pitches the camera up and down, then settles into a proper leveled position (see--and listen to--the video of startup).
  • With the power on, the camera keeps itself in the proper position, snapping back to center after being moved in all three directions (startup video)
  • BUT, two other issues are occurring:
    • You will note in the video that when the camera is rolled to the left far enough, I get an ugly grinding noise. In flight, the drone would rarely roll that much except perhaps during a significant course correction at high speeds in sport mode. But, still, there's a problem there.
    • Also, note that when the camera is pitched downward, it snaps back to level, but when it is pitched upward it snaps into a slight downward tilt and stays there until the power is cycled off then on again.



I've done an ICU calibration, gimbal and compass calibration. I'm not getting any errors (other than the backward vision sensor calibration failure).

I understand that the yaw motor is usually the first to be impacted in a crash but it seems OK. But it is not being activated during calibration.
The roll motor seems to function under normal flight conditions even though it's not being activated during calibration, but it would seem it's taken some damage.
The pitch motor seems to be working but what is the deal with the slightly downward angle after pushing it upward (but not downward)? Electronic speed controller? Something else?

None of these parts are easy to find--if I don't want to take my chances waiting a month or two for a part that may or may not actually work. So would you be replacing the roll motor, pitch motor, yaw arm, ESC? None of the above? All of the above?

Maybe it's all working fine but my drone is mad at me for letting a tree beat it up, in which case I'll talk to it nicely until it comes around. I'm guessing that won't prove successful, so any advice would be greatly appreciated.
 

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With the visible damage at the the point where the landing legs connect, I would question whether all that would effect the antenna and compass operation.
Hope you get it solved.
 

Capt KO

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For a start, Replace bent arm and most likely the ribbon cable (with oem only). Ribbon is damaged easily in a crash. These parts are inexpensive, available, and may be enough. Then can you diagnose the rest, if needed.
Good luck
 
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For a start, Replace bent arm and most likely the ribbon cable (with oem only). Ribbon is damaged easily in a crash. These parts are inexpensive, available, and may be enough. Then can you diagnose the rest, if needed.
Good luck
Thanks. Good point about the cable. The connections all look good but the cable could still be damaged.
 
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With the visible damage at the the point where the landing legs connect, I would question whether all that would effect the antenna and compass operation.
Hope you get it solved.
Thanks for that. I questioned that, too. There was a bit of pinching and one of the compass wires was damaged. I repaired that. Then tested and both the antenna and compass seem to be working properly. I'll be replacing both landing skids as well.
 
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I may be incorrect.
but if we are going by the attached pictures, there is no way that gimbal is going to process correctly with the arm bent like that.
That's the weird thing...I would have expected that too, but the video seems smooth, the horizon stays level, pitch control dial is working.
 

Droneted

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Hi this is Droneted. If I were working on it the first thing I would do is check the Hall sensors. The yaw hall sensors are hard to see. I use a jewelers loop to see them. You usually have to remove the yaw motor and take the drum off. I have a YouTube video that will show you how. I am in Mexico today but will be back tomorrow. Email me some photos and I will help you.
[email protected]
 
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That's the weird thing...I would have expected that too, but the video seems smooth, the horizon stays level, pitch control dial is working.
I have found that, while the yaw is usually the culprit, that the pitch motor has a lot of effect over proper gimbal function. I have had the pitch do exactly what you are describing even after a yaw motor replacement. I would bet your pitch motor has a lot of wire coating melt on the copper wires. If gimbal motors are forced into an unnatural position, like in a soft crash, and allowed to stay that way for a few minutes, the motors overheat, hence, coating melt. Follow Teds' YouTube video & take the drum off the pitch motor and inspect the wiring. Keep in mind that the wires did not have a fillet type of gloss to them when they were new.
 
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Hi this is Droneted. If I were working on it the first thing I would do is check the Hall sensors. The yaw hall sensors are hard to see. I use a jewelers loop to see them. You usually have to remove the yaw motor and take the drum off. I have a YouTube video that will show you how. I am in Mexico today but will be back tomorrow. Email me some photos and I will help you.
[email protected]
Hi Droneted.
Hi this is Droneted. If I were working on it the first thing I would do is check the Hall sensors. The yaw hall sensors are hard to see. I use a jewelers loop to see them. You usually have to remove the yaw motor and take the drum off. I have a YouTube video that will show you how. I am in Mexico today but will be back tomorrow. Email me some photos and I will help you.
[email protected]
Sounds good. I’ll do that, thanks.
 
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I have found that, while the yaw is usually the culprit, that the pitch motor has a lot of effect over proper gimbal function. I have had the pitch do exactly what you are describing even after a yaw motor replacement. I would bet your pitch motor has a lot of wire coating melt on the copper wires. If gimbal motors are forced into an unnatural position, like in a soft crash, and allowed to stay that way for a few minutes, the motors overheat, hence, coating melt. Follow Teds' YouTube video & take the drum off the pitch motor and inspect the wiring. Keep in mind that the wires did not have a fillet type of gloss to them when they were new.
Thanks for that suggestion. Good tip to look for signs of overheating.

I think I’ll (carefully) have a look at all three gimbal motors’ sensors. The roll motor is the one that grinds a bit, the pitch motor returns to a downward angle if pushed up but will reset to center if I use the gimbal down/up button, and the yaw motor, well, it’s the yaw motor so it probably hasn’t made it through this undamaged.
 
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So, does anyone have a trusted source for gimbal motors? Had any luck with a specific vendor? From what I’ve been reading, it’s a bit of a roll of the dice whether I’ll get one that actually works from the eBay/Amazon vendors.
 
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I just bought 2 yaw motors for Phantom 3 from eBay vendors wfyb (US) and zhengzhengstore (HK). Both yaw motors were good. Took about 3 weeks for shipping.
 

Droneted

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I am back from my vacation. I have read through this post again. It can have a bent yaw arm and still work smoothly. In that case just replace the Yaw arm and maybe the ribbon cable. Only use an OEM ribbon.
 
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I would be glad to help if you explain what is going on with it.
Hi sir
My drone met a crash recently into power lines. Drone survived to hover after crash.
But body, yaw motor and landing gears were damaged.
Yaw motor was in half hanging position when i landed the drone.
Flex cable and yaw arm was intact but when i changed yaw motor reassembled the drone
And
When fired up, the gimbal occasionally makes an unhappy sound, pitches the camera up and down, then settles into a proper leveled position.

I did 14-15 test flights. I heard the unusual sound 5-6 times.

Another issue is

Drone fell down twice in 14 test flights on ots own
Showing motor failure
But jn rest 12 flights it flew normally
No error is recorded in flight logs
 
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I just bought 2 yaw motors for Phantom 3 from eBay vendors wfyb (US) and zhengzhengstore (HK). Both yaw motors were good. Took about 3 weeks for shipping.
Thanks for that tip. I'll be having a look at the motor sensors this evening and look into those vendors if necessary.
 

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