Rising from Ashes

When last we left our heroes …

Flying a drone was always about photography. Years ago, I built the huge hexa-copter, we had dubbed Dragonfly, its purpose was to carry the miniaturized but still kind of heavy Fuji X-M1 camera. Including the battery and the 27mm F/2.8 lens, the payload for the drone was 407 grams. The camera featured an APS-C-sized 16-megapixel image sensor (23.60mm x 15.60mm).

While looking impressive on the ground and even more so in the sky, without a gimbal stabilizing the camera, this setup produced only a few usable results. Adding a gimbal and still keeping the weight of the payload reasonable meant sacrificing the quality of the camera. A 3D gimbal combined with the 12-megapixel GoPro HERO 4 (sensor 1/2.3″) weighed just 254 grams and could be flown by a nimbler copter, like those we had dubbed Phoenix, Icarus, or Titan.

Tom took the Titan to Washington when he left for the big city on Puget Sound in the Pacific Northwest, but I don’t think he ever had it fly there. I sold the Icarus with all the batteries, controller, etc., before leaving Ramona for Sedona, Arizona.

Times have changed dramatically as they always do

After not having flown a drone for more than two years, I did not build but bought a drone. The tiny DJI Mini 2 is probably more capable than the drones talked about above. The whole setup weighs less than the 3D gimbal with the GoPro camera. It features a 3-axis motorized gimbal and the 12-megapixel camera (sensor 1/2.3″ 6.17 x 4.55mm) delivers 4K/30fps video. The drone, including a gimbal, camera, and battery, weighs a little under 250 grams.

 

DJI Mini 2

  • Takeoff Weight < 249 g
  • Dimensions
    • Folded: 138×81×58 mm (L×W×H)
    • Unfolded: 159×203×56 mm (L×W×H)
    • Unfolded (with propellers): 245×289×56 mm (L×W×H)
    • Diagonal Distance: 213 mm
  • Max Ascent Speed: 5 m/s
  • Max Descent Speed: 3.5 m/s
  • Max Speed (near sea level, no wind): 16 m/s
  • Max Service Ceiling Above Sea Level: 4000 m
  • Max Flight Time: 31 mins (measured while flying at 4.7 m/s in windless conditions)

Sensor

  • 1/2.3” CMOS
  • Effective Pixels: 12 MP

Lens

    • FOV: 83°
    • 35 mm format equivalent: 24 mm
    • Aperture: f/2.8
    • Focus range: 1 m to ∞
  •     Shutter Speed
    • Electronic Shutter: 4-1/8000 s
  •     Max Image Size
    • 4:3: 4000×3000
  •     Video Resolution
    • 4K: 3840×2160 @ 24/25/30fps
    • 2.7K: 2720×1530 @ 24/25/30/48/50/60fps

Image-Sensor Sizes Comparison Chart

Image Sensor Sizes

The DJI Mini’s image sensor is probably just a little bit better than what’s in a decent smartphone (e.g. iPhone 12 Pro Max’s ultra-wide sensor : 12 MP 1/3.6″, f/2.4-aperture lens) but as we’ve all learned, the best camera is the one you have with you.

If the a single image doesn’t provide enough resolution, stitching together panoramas can create useful results.


DJI Mini 2 Power system error Code: 30210

It was rather windy for days, not good to fly, and when the wind finally dyed down and I wanted to launch the done, this error code appeared:


Preflight Check – – – Unable to Take Off
Power system hardware error. Restart aircraft  (Code: 30210)

Looking for help on message boards like MavicPilots, I discovered that this error message is not all that uncommon and usually means that the ESC board needs to be replaced.

DJI Mini 2 ESC and Power Circuit Board

This board contains all four electronic speed controllers and connects to the motors with three wires each. The ESC board connects to the main board (which is located underneath the battery compartment) with a flex cable and also to the pretty much useless front LED. The ESC board can be found on eBay for about $30.

DJI Mini 2 ESC board

Unfortunately, replacing the ESC board didn’t change a thing and the error code 30210 remained.

Before ordering and replacing the board, I concluded the motors were fine. I had carefully and meticulously cleaned the motors. All four motors were able to spin freely and showed the common brief back and forth movement when the Mini2 was powered on.

DJI Mini 2 Motors

I didn’t want to accept that the DJI Mini 2 had turned into a brick and therefore ordered a motor on Amazon. Since a motor cannot be order separately, only as full motor arm replacement, I order the cheapest arm I could find ($23.90).

It’s rather easy to remove/replace motors on the arms. Since the front arms also contain the antennas, I started with the replacement of the rear right motor: removing the original motor with the one I got from Amazon.
Turing on the controller and powering the DJI Mini 2 …

Preflight Check – – – Unable to Take Off
Power system hardware error. Restart aircraft  (Code: 30210)

Assuming that the original rear right motor wasn’t the issue. I used it, replacing the rear left motor.

Turing on the controller and powering the DJI Mini 2 …

Preflight Check – – – Normal

Final preparation before take-off

What all this means is that the rear left motor turned bad somehow. Replacing it was not easy, but not all that hard either. What was hard however, was to discover which component needed to be replaced and ever since DJI started encrypting the hardware log-files, this process got a lot harder.

I made sure the 12 solder joints on the ESC board looked solid, added a few drops of hot clue to secure the flex cable connecter, and tidied up everything, before re-attaching the top cover. No I didn’t ..

Well, I did do all these things, but only after doing several short take-off – hover – land tests in the driveway. Currently, the DJI Mini 2 works nicely and I don’t see it behaving differently than before the ESC board and motor replacement. Here is an evening/night shot, also exposing the shortcomings of the small sensor, i.e. low light performance.