Following on the heels of the highly acclaimed Mini 3 Pro,
DJI’s sub-$500 Mini 3 aims for most of the same features of the Pro for $200 less.
The compromise? A lower resolution camera, no obstacle avoidance system,
and the OcuSync 2.0 protocol in place of the newer OcuSync 3.0 protocol.
If you didn’t understand any of that, then chances are you’re not missing much,
because for the casual flier it means you lose obstacle avoidance and you save $200.
Hardware differences aside, one thing is certain with drones: you’re going to crash.
And when you do, you’ll want to be able to fix your drone ASAP so you can get back in the air.
Thanks to Creative Electron for the awesome xrays!
Let’s get this teardown started and take out the battery to have a look inside. As
the most commonly damaged components, the eight rotor blades are easily removed with a Phillips
head driver, if only motor arms were this easy to replace. And in case you’re wondering, the blades
are one of the few parts you can buy directly from DJI but good luck finding them in stock.
There’s a total of 6 screws on the underside of this drone. When you’re
aiming for less than 250 g, every single part must justify its presence so it’s
no surprise to see fewer metal screws and lots of light, but stubborn plastic clips.
Removing the top cover reveals the GPS board stabilized on rubber pillars. This glued up
section houses a 6-axis MEMS accelerometer, gyroscope, and a pressure and temperature sensor.
The spudger makes short work of the rubber grommets, oh and glue—a
lightweight solution to micro-vibrations, something we'll be seeing more of.
With the camera cable away, a single screw is all that’s left securing the
heatsink revealing the lower sensor assembly connector, the motor control board connector,
RF antennas leading to the tips of the motor arms,
and a single screw that wouldn’t budge without a bit of emotional support from the battery pack.
The mainboard is free allowing us a closer look at the meat and potatoes of the Mini 3.
This shiny fella here is a Synaptics 5G, WiFi, Bluetooth, and FM receiver IC. That sits alongside
256MB of Toshiba flash memory, 256MB of DDR3L, and an 32-bit ARM Cortex M7 clocked at 600 MHz.
On the reverse side we have a 32-bit ARM Cortex M4 and another 256MB of DDR3L.
Also the Ambarella H22 SoC running a quad core ARM Cortex A53 clocked
at 1 GHz together with everything else you’d need to stream at 4K resolution.
And if you happen to stream yourself into a tree, perhaps the most expensive repair you’ll ever need
to perform will be a camera assembly replacement, though if you’re lucky you might only ever need to
replace these rubber gimbals. A pain to remove and an even bigger pain to replace, they’re still a
sight cheaper than a camera assembly. The process is relatively straightforward if somewhat fiddly.
Another common repair, the motor arms, are susceptible to breaking as they’re
often the point of impact in a collision. Unfortunately, the cables running through
the arms are soldered to the PCB, probably to keep a stable connection and keep this thing compact.
The PCB holding all eight solder connections is secured by three screws and would ideally
be a tad easier to access. I ended up removing the bottom cover and the IR
assembly to get at that board. If you’re looking for a repairable drone, be warned,
everything is packed in tight and definitely needs a certain amount of patience to disassemble.
Following up on that housing, the lower sensor assembly consists of an IR emitter and a receiver,
plus a camera. This assembly, working alongside the GPS and MEMS sensors,
is responsible for keeping the drone level in flight.
All this sits on its very own dedicated bracket held down by
another four screws. Disconnecting the motor arm LED cables finally allows me
to wiggle the motor controller PCB free to take a closer look at it.
All the drone motors hook up to this board which acts as the motor controller,
driven by yet another 32-bit ARM Cortex M4 SoC.
And what’s this little guy hiding in the corner here? That’s a 3-axis magnetometer capable of a
heading accuracy of 0.5°. That means the drone can find true north to within half
a degree of accuracy. By comparison, I got lost in central Glasgow for two hours once.
All in all, your average drone enthusiast would probably find this device to be fairly
repairable if you could actually find the parts. Rummaging through eBay listings
for broken drones that may or may not have working replacement parts can be expensive.
And if you want repairability, custom drones are still going to be your best bet.