PH4 gimbal yaw motor solved?

[madius]

Hi everyone,

after trying many things, researching, reverse engineering and a lot of headaches, I think I'm close to solve the yaw motor orientation problem of the phantom 4 gimbals.


Introduction

when we change the yaw motor of a phantom 4 gimbal (whether STD, PRO or V2) it is usually not pointing forward centered.
there are many posts that talk about this issue, but I don't think anyone has found a solution at the time of writing (Oct 24).


How does it work?

the motor is a brushless type and has two hall type sensors located in the pcb flex of its stator.
The signals of these sensors are connected to the ESC board through the flex of the motor.
The Roll motor works in the same way (it never fails), and serves to measure and compare the signals when the system is operating correctly.
In the forums there is a theory that the gimbal control reads both signals and moves the motor until both are the same, i.e. they have the same voltage value, that way it “should” be centered pointing forward.


Testing and research

I found the signals coming from the hall sensors (both yaw and roll) in testpoints on the ESC board.

After soldered wires and measured them with an oscilloscope, I check on one drone that works fine and on another with the problem.
I have measured sensors voltages of drones that are working and when the camera is centered facing forward, the values between each sensor are different.
In the same way you can measure this behavior in the ROLL motor.


Modification

I built a resistive divider to interrupt the signal between the sensor and the microcontroller that reads the value.
That with Y1 and Y2.

I spent hours playing with both presets and testing combinations.
Once I managed to improve the angle, I measured the value of the presets and replaced it with fixed 0402 resistors and placed them in the ESC pcb.

conclusions

Although I managed to move it a few degrees and it was operative, I could not get it centered.
Clearly it is not the definitive solution, but I wanted to share it with you and hear your opinions.


thanks for reading

 

[Capt KO]

If you reuse the outer shell of the original yaw motor during replacement, the camera will always face forward upon completion. Watch the youtube video by our very own @Droneted explaining the how-to steps in detail. I've done it several times already on various P4 models with 100% success.

 

[madius]

If you reuse the outer shell of the original yaw motor during replacement, the camera will always face forward upon completion. Watch the youtube video by our very own @Droneted explaining the how-to steps in detail. I've done it several times already on various P4 models with 100% success.

Hi Capt,
I know that, and that's the way I usually repair them, but there are times when you don't have the original bell or it's damaged and you have to replace it.

 

[Droneted]

Hi Capt,
I know that, and that's the way I usually repair them, but there are times when you don't have the original bell or it's damaged and you have to replace it.

Most of us repair guys hang onto the casings so we have a pile of casings to try. I have about a hundred. There are about 5 or 6 different magnet positions. Somewhat easy to identify the one needed.

 

[madius]

Most of us repair guys hang onto the casings so we have a pile of casings to try. I have about a hundred. There are about 5 or 6 different magnet positions. Somewhat easy to identify the one needed.

Hi Droneted, I have 26 differents bells, and I keep accumulating, and I usually try them when I don't have the original bell of the drone.
Anyway, there are times when you don't manage to solve the problem.

 

[Droneted]

Hi Droneted, I have 26 differents bells, and I keep accumulating, and I usually try them when I don't have the original bell of the drone.
Anyway, there are times when you don't manage to solve the problem.

Do u use a compass to identify the magnet location

 

[Falkon]

Do u use a compass to identify the magnet location

Of course not! It's crude and doesn't guarantee success. There are modern methods. Magnetic film for visualization. Take your pick.

 

[Droneted]

Of course not! It's crude and doesn't guarantee success. There are modern methods. Magnetic film for visualization. Take your pick.

You mean my Boy Scout compass is crude and not accurate? Heaven forbid.
I advise using it because it is easy to get. I do like your suggestion and will order one today. Most do it yourself guys and gals don’t have access to such modern tools. Boy Scout compass is the easiest to get locally. At my age ( 81) I go with easy

 

[Droneted]

You mean my Boy Scout compass is crude and not accurate? Heaven forbid.
I advise using it because it is easy to get. I do like your suggestion and will order one today. Most do it yourself guys and gals don’t have access to such modern tools. Boy Scout compass is the easiest to get locally. At my age ( 81) I go with easy

I have the film on order and will repost after I try it out. He is right about the compass being crude. It only gets you somewhat close. Still some trial and error involved. I am working on one right now that points left. It is so far out that using a casing where the magnet is all the way to the right only get it near center but not close enough.

 

[Droneted]

I have the film on order and will repost after I try it out. He is right about the compass being crude. It only gets you somewhat close. Still some trial and error involved. I am working on one right now that points left. It is so far out that using a casing where the magnet is all the way to the right only get it near center but not close enoug

Ok I have the film. Trying to figure out how to use it. It shows 8 magnetic locations. They are slightly different on each casing. I assume half are positive and half negative. Using a Boy Scout compass only shows half of these. I assume the half I see are either positive or negative. Not being a that smart I am not sure how to process this. There are a lot of instances where the yaw casing is missing or was replaced with the wrong one and I have to figure out what casing is needed to move the yaw left or right in order to center it.
Anyone out there with the knowledge to help?