Velocity, thanks for the hint
Doing some research, there is a difference how Hobbywing V4 sends signal than they did befor with v3 and others ESC do.
Has to do with Open Collector output as required by usual FBL, but V4 sources with high impedance output, which sometimes workes and sometimes not, due to different Voltage levels.
Have you tried to change BEC Voltage level? This might help...
http://www.helifreak.com/showthread.php?t=744062 See Post #16
Vortex Beast VStabi all got challenges with HW V4.
http://www.helifreak.com/showthread.php?t=727317Solution:
1) use external phase sensor
2) If you got right skills, use impedance changer, like a NPN transistor to rebuild open Collector, but I strongly suggest to use at least a 1k Series Resistor in front of Basis Pin.
RPM Signal to Resistor 10k and this to Transistor Base PIN / Emitter PIN to Ground / Collector PIN to FBL Phase PIN
http://www.helifreak.com/showthread.php?t=744062If I had a HW V4 at hand I would test the NPN Transistor, maybe someone can test it.
Maybe Tomas can comment......