BEC voltage fluctuating -> reboot

[jstjern]

Just put together my mini, and during earlier assembly and testing I had the tail servo unplugged, so did not notice:

– When the servo is plugged in and idle, everything is at 5.0V, but the smallest fluctuation will have the BEC voltage fluctuating between 4-7V, verified by telemetry and a multimeter. No prob without servo, but same issue with a Multiplex Tiger Digi4 (45g slower digi servo, just for testing). I resoldered all pads on the LM2940 and the caps, but same thing. The board will reboot regularly during fluctuations.

– The other odd thing – when despite this trying to reduce the range of the yaw servo in the clearflight app, as per the video, the range is strange. Min is only a few hundreds, max 23400 or something and mid=0. Trying to change these and press save, does not save anything. Other settings are saved. Bewildered…

Any thoughts?
Jonas

[LeoTheHuman]

There are some problems with servo tab in current CF configurator. Feel free to study and use “servo” CLI command.

[Terje]

And by study is meant:

The syntax is in CLI is:

servo [ENTER] gives you the current values.

Setting new value:

servo 5 1100 1900 1500 90 90 100 -1

Where 5 is the servo (default)
1100 is the minimum value
1900 is the maximum value
1500 is the midpoint.
-1 is the normal direction (default – as opposed to reversed)

Remember to write “save” and press [ENTER] to save values.

You probably only need to tinker with the midpoint (1500) value if you are following @Davids video.

[jstjern]

Thanks for the cli tip.
Either a faulty tantalum on the regulator output or a zipped LM2940 methinks… Waiting for David’s comments, will bypass with separate bec for now to get in the air…

Jonas

[jstjern]

The LM2940-5 was faulty. It works normally now. Thanks, David, for the excellent customer service!
Jonas

[Matthew]

Since we are on the topic, why does the servo command user ‘servo 5’ when the servo is plugged into servo 1 output? This differs with what I found in the Cleanflight docs. (Perhaps this is related to the issues with Cleanflight configurator on the servo tab)

Additionally, what are the fourth and fifth values in that command (the 90s)? I wasn’t able to find documentation for that anywhere.
servo 5 1100 1900 1500 90 90 100 -1

[Author]

Posts