MPI Servos, Any Good?
The current MPI coreless servos are the same ones FMA was selling as their 35xx/36xx series up through early last year. I have a bunch of the FMA ones on-hand and a couple of the MPI versions.
They are strong, very fast and center quite well. I've only run them on 4 cells - never saw a need for 5.
However I've had two of these servos die in the same plane over the past couple of weeks.
The first failure was the rudder servo - it died in-air. The reason: one of the wires brroke loose of the motor. I resoldered both wires and potted them with RTV and its working fine.
The second servo was the rudder servo. This one died after a normal landing - when I walked over to retrieve the plane the elevator was in the full-up position and was nonresponsive to the TX stick. OMFG. I'm glad this one stopped working on the ground!
After a couple of minutes of sitting with the rx still on the elevator servo went zip! centered itself and worked like normal. Need I say that I didn't fly that bird again that day?
I haven't diagnosed the second failure - too busy. I suspect another broken wire, though.
Weird timing. I have recently swapped in a more powerful engine into this particular plane - perhaps there's some unusual vibration that wasn't there before.
BTW I have about a year on this particular airframe, and have never crashed it nor any of the on-board gear.
I plan to pull the remaining servos, inspect and resolder any dodgy joints then pot the wires with RTV.