i'm sure it's some kind of a voltage drop problem, b/c i've never had any other issues with the dx-7. i also dont think it's a signal problem b/c if the receiver loses signal from the radio, the servos will just go into "fail-safe" which is the neutral positions (established when you bind the system), correct? but i crashed b/c it DID NOT go into neutral. instead the servos got "stuck" at the last input position (which caused it continue to roll until hitting the ground).
Nope, the failsafe on the DX7 doesn't go to set positions (except for the throttle), it holds the last command.