APM 2.6 Refuses to Arm - Throttle Fail Safe Problem

I have an FPV quad that I bought used that had been flying fine. I got it home and went through the setup wizard and everything seemed fine.

But it refuses to arm. I’ve been trying for 3 hours to figure out the problem and gotten nowhere. I’ve watched a half dozen videos on how to set it up, and mine is set to (what I believe to be) the correct parameters. But no matter what I try, when I try to arm it there is the following message on the flight data screen: PreArm: Check FS_THR_VALUE

So it’s clearly a problem with the fail safe settings. But for the life of me, I can’t figure out what the problem is.

With the transmitter on (JR 9503 w/Spektrum AR9020 RX), the Radio 3 value is 1123. With the TX off, the value is 965. The Fail Safe PWM is set to 970. That’s just what it’s set to now. I’ve tried many, many combinations - all with the same results.

Just to see what would happen, I disabled the failsafe. But even after doing that, it still won’t arm.

What do I have screwed up?!

Please provide tlogs and/or data flash logs to help troubleshoot your issue.

OK, stupid question (please be patient with me - I’ve been in this hobby for 25 years, but am a total noob in dealing with the APM and Mission Planner software):

How does one capture and save the log files?

copter.ardupilot.com/wiki/common … etry-logs/


Another question: I think it might be a good idea to do a factory reset on the APM since I bought it used. I did several Google searches, but have not been able to find any details except for an outdated Wiki link.

So how do I perform a factory reset on the APM 2.6?

Try writing the default values from Mission Planner. Make sure you have selected the proper platform.
I did this after chasing down various issues and it cleared up at my pre-arm issues

I found a video on the YouTubes for how to perform a reset using the CLI. Then, I cleared the model data in the TX and started the setup from scratch using the Wizard.

That seemed to do the trick. I was able to arm the APM and get the quad to fly. It’s a bit wobbly, though. So I may need to tune the gain settings.