The replacement flight controller came in so I could follow up on the repairs from last time, where I realized I had two bad ESC’s after finishing the rebuild. When flashing my new replacement for the replacement flight controller, I noticed that there were two firmware targets that were very similar: MATEKF411 and MATEKF411RX. I had picked the RX version thinking that was for FC’s with built-in receivers. I’m not sure that’s what the RX means in this case as there’s also an SE target. It doesn’t matter anyway since these FC’s don’t have built-in receivers, I was confusing it with the flight controller that I had recently used on my whoop build.

So for the new flight controller I smartly used the correct firmware, the MATEKF411 version, and the new board tested out fine both in Betaflight and BLHeli. All the ESC’s were recognized and I even plugged in motors and made sure they all spun up. Then I had the thought that maybe the problem with my other FC was because of the wrong firmware. So I plugged that in and flashed the same firmware on that, and checked in BLHeli and all four ESCs were recognized. The board and ESCs were fine all along, I just had the wrong firmware loaded so the resource mapping was incorrect. I’m honestly surprised that it worked at all but I’m guessing that the major difference between the two models is the pin assignments on the main chip. I’m glad I didn’t brick it or burn anything out.

I honestly wasn’t expecting to prove out my comment from last week so soon, but there really is always something new to learn in this hobby.

Now I had two working flight controllers. One was all soldered up and just needed to be remounted on the carbon fiber frame, I even had some extra foam to use since I’d torn off the foam padding that was originally stuck on figuring I wouldn’t need it. The other FC was better designed for a toothpick style frame with it’s sideways mounted USB and motor plugs, but it would have to be soldered to the receiver and video transmitter. So I had to decide on which way to go. While I really liked the design on the new board, I decided to use the other one since it was already soldered and just needed to be mounted. I’d save the new flight controller for when I busted the current one or decided to build a new quadcopter.

I remounted the flight controller and other electronics on the frame, and got the quad rebuilt in time for a little test flight one evening when there was decent weather. The first battery went well. For the second one I bumped the video transmitter power up from 25mW to 200mW, which gives me a better picture when I have obstacles between me and the quad. After making that change the video started to go to snow and then cut out whenever I would throttle up. I was not happy. I’d only got one flight in before a new problem had popped up.

So the next two nights I spent a lot of time troubleshooting the problem. I checked solder joints. I looked for damage to wires and electronics. I tried with the canopy off so the VTX was hanging loose from the flight controller, and noticed that it worked better that way, so I tried a different set of screws and standoffs to have the canopy sit higher off of the flight controller but that didn’t work either. I tried replacing the wires on the VTX harness. I tried direct soldering the wires from the flight controller to the video transmitter. Nothing worked and eventually I’d run out of ideas to try. The problem seemed to be getting worse too as it was a now having issues when the VTX was loose, and started to cut out completely until I restarted it. So I gave up and swapped out the video transmitter for a new one. I’d bought two the last time I needed to replace it, so I already had a spare.

After getting the new video transmitter installed everything worked perfectly. I’m not sure what caused the last one to fail. Possibly I messed up something when soldering, either the board got too hot or I bumped something. I don’t think so, since I normally notice those things. It might just have been cumulative damaged from crashes and just vibration form flying that finally stopped it from working. There’s no way for me to know, and it’s one of the hardest things for me to deal with in this hobby, not being able to determine exactly what happened and why.

We had cold but sunny weather on Sunday, so I was able to get get out and fly my yard for a full six packs before my fingers got too cold. I didn’t have any more trouble with the quad. Finally.

I’ve been very happy so far with the all of the flight controllers, canopy, motors, and frames that I’ve bought from BetaFPV but I think I’m done with their A01 VTX’s. I’m on my third one for a quad that I’ve had for about seven months, and it seem like they should last longer than that. So I’m looking at some other manufacturers for alternatives to switch to when this one dies. Or maybe I’ll find that a couple of months is just about as long as these last. Or I’ll get a surprise and this one will end up lasting for a year.

Repairs Revisited
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