Saturday, 16 May 2020

Tello Motor Repair done right!

How to change a Tello Ryze Drone motor

Other instructions on the web


Before attempting the repair, I checked the web for tutorials. But found most of them pretty terrible, usually causing permanent damage or ugliness to that nice drone.
All except one from DroneZone, which I only fond after having finished the repair :-(

That is what a decent job looks like

Tools required

While not really a tool, you need a replacement motor. There are several sources on the web, but they come with small weirdnesses like gears or plugs. Like so often, I got mine from Banggood. They come in two wire lengths (71mm or 87mm), but as a wire can never be too long, I went for the 87mm, although I needed to replace a front motor, where the leads are shorter.
These motors are properly keyed, so you can't confuse the clockwise and counterclockwise motors.

Other than that, good quality precision screwdrivers are a must. Poor screwsrivers ruin the screws. I currently use both a Wowstick, and traditional hand tools, depending on the job at hand.
And of course the wonderful, regulated Mini TS80 soldering iron. The first USB iron that doesn't suck. It does not come cheap, but during the building renovations, when I had no lab space, I learned to love it and won't go back to my old Ersa iron.

Other household items include
  • a pin to peel off the gunk that seals the solder points
  • wire cutters / needle nose pliers
  • Tweezers are handy, too

Problems encountered

If you follow my video (see here), you will find that I struggled at a few points

Cracking the case open

The plastic is very thin, so go around the edges carefully with a spudger.

Removing the gunk over the solder pads

This was a pain. I tried several methods. What worked best in the end was to peel the silicone-like gunk off with a needle. No great fun.

Soldering

Desoldering needed more heat than I thought, given the delicate wires. That might have to do with the solder. I set the iron to 340 degrees centigrade. Later, when soldering the new wires to the board, the joints went dry immediately, so I replaced the solder. (Using solder wick)

Hotglue over the cable duct

Where the motor wire enters the body, there is a drop of hot-snot over the groove the wire runs it. This needs to be cleaned out.

Getting the motor out

That was not really hard. I could pull it out with my pliers, but the cable running through the motor holder gave quite a bit of resistance. So I smelled trouble getting the new wires in.
Motor arm

Putting the new motor in

The actual trouble is to get the new wires through the tiny hole in the motor arm. The trick is to bend the wires at an angle. You can see that in my video.

Final words

After the repair, I went through two freshly charged batteries. No problems. And other than in some repair videos, the drone does not look like it had been chewed up by a dog after the repair.


Friday, 15 May 2020

Benefits of using hardware encoding on an Intel HD 630 with ShotCut

CPU Power vs GPU for Video Processing

My prefered video editor
Shotcut Video Editor

Hardware

My Fujitsu Esprimo Q957 is more of an office PC than a Video editing, Coding, 
CAD or hardware experimenter's platform. But for the space it takes on my much-too-small desk, it does an amazing job in all of the above disciplines.
CPU-Z shows the GPU
So all in all, I didn't think the integrated GPU could help me getting the jobs done more quickly.

Encoding on the Intel HD Graphics 630

A near 15 minute video I currently work on, needed an unusually high number of modifications. Each with a lot of noise from the fans running at full speed.
100% CPU
This took nearly 8 minutes at an unpleasant noise level. Time to investigate alternatives...
Let's try that...
Involving the GPU is amazingly efficient. Less CPU usage and the GPU at a little over 50%, along with somewhat less noise.
CPU-wise this does not look like a massive difference, bit it is.
The best part: Videos now encode in half the time. Much better than what I had expected from an integrated "Office-PC" GPU.
Success! Less than half the time :-)

PS: Here is the link to Shotcut (free and open source)

PPS: To my amazement, the tiny Fujitsu desktop easily outperforms my relatively recent Surface Laptop 2. The benchmark only shows a little over 10% difference ( https://cpu.userbenchmark.com/Compare/Intel-Core-i5-8350U-vs-Intel-Core-i5-7500T/m388461vsm218898 ), but the system takes 6 minutes for the same job as above, even with the help of it's Intel HD 620.