I don't know if this is normal, but I noticed this strange behavior with two of my Futaba 2.4G receivers R617FS (7ch) and R6004FF(4ch micro) consistently with Futaba 3004 and Tower-Pro SG90 micro servos.
this is what happens: If I keep the Tx off and cycle Switch-On-Off the Rx switch harness, with every ON, the servo travels to one of the end monotonically, unless it reaches the extreme. After that, it makes a 'Click' sound (poor gears grinding) with subsequent Off->On, but wont move. If I switch on the Tc, the Servo immediately goes to center position.
This really scared shit out of me. Is this normal ? I mean it can really damage you Servos ? This behavior actually caused to dismantle my glued Servo from the 'Foam' mount as I had put the Arm with the wrong (spuriously traveled) servo pinon position.
On the side note(may be wrong place), I have noticed my Tower-Pro SG9 (9 gram) micro servos doesn't fit the Arm in exactly 90 degree to the servo case. The Arm fits the pinion making at least 15-20 degree angle which I need to trim with at least 30% bias, loosing the throws by as much as 30%!! Is this again a normal stuff or just the cheapness of these Chinese clones ? One can live with them, but its nice to build a plane which has all the surfaces in right places without trimming, and you leave the trimming for those 'in-visible' artifacts.
-Ujjwal