JR DMSS—important hints!

This issue should be solved by using the latest TX firmware from JR Website now.

If still using a old TX firmware follow the steps below.

During IRCHA 2012 we had several pilots out there with some Governor issues on electric helis. They all had in common:

  • all were using JR radios with DMSS
  • all recievers were connected to VBar with standard patch cables and configured as standard recievers in VBar.
  • the had unwanted motor shutdowns in flight, the pilot does not touch any switch
  • in the log is always a "governor off" and "governor on" (could be vice versa too) at the right time, possibly with a "signal out of range" too.
  • at the end some ESC could be damaged too

So ... we tested several things and it seems to be that the reciever gives a valid "motor off" signal (-100 % in VBar) to our RPM preset / AUX input channel. VBar turns the motor off, and in the same second we will get a "motor on" (valid RPM as set on TX form 0-100 %) again. The motor is electrically off but still turning, and the ESC now tries to commutate new for a start into the still-rotating motor and its magnetic fields ... and maybe damaged too.

After all it is definitely a issue with the JR radios and not a VBar issue. We talked to JR and showed them what happens here. They will surely work on it but it will take some time. We also don't know if other functions will be effected too. If the signals are in a valid range on each function we have no chance to notice this. Only the governor event log entries with the motor on/off pointed us to the right direction.

Anyway, we have a solution for the governor to avoid this motor shutdown in flight. We use the expert mode with bankswitch because a bankswitch waits a few milliseconds more for a constant bankswitch signal and a short wrong signal wont have such a effect like using the RPM preset from TX.

Click here for the Description how to do this

Have fun now! - Please check the log after some flights to be sure other channels don't have any signals out of their range. Whenever valid (but not caused from the Pilot) signals will be there we have no chance to make this visible.