[BrianG]

Well, hooking the MMM to the link cable tells you the brains are ok as long as they are getting an external power source (via the link). When running, the BEC powers the brains and external servos. Well, if the BEC is bad, both the servos/receiver and the brains won't get the power. So, backfeeding an external BEC voltage INTO the MMM (as well as to the servos) "should" power the brains too. That is unless the MMM BEC FET isn't shunting battery voltage to the output (similar to the CCBEC has been reported to do).

Basically, just hook an external BEC but don't remove the red wire in the throttle cable. However, before you do this, I would measure the output voltage of the MMM BEC to make sure the output is in fact 0v (or close to it). If not, DO NOT do the backfeeding thing. Also, keep an eye on the external UBEC temps. If it gets hot then the MMM BEC is causing more issues.