I am new to this forum. I currently have a Mercury SRS w/o GPS. I built a brand new 100cc 3D airplane setup. Unfortunately, I have burned up 3 brand new HV servos with this Mercury Powerbox. During the initial setup, everything was working fine for the 1st 4 flights. On the 5th flight, I had a brand new Futaba 9177 elevator servo lock up in flight and lost the plane. I purchased a new airplane, and in this setup, I'm running Savox 2290hv servos. During the setup phase, I mounted all servos without servo arms or linkages. I powered up the Mercury powerbox and all surfaces seemed to be working well. After about 3 minutes, I noticed a sharp flash and the rudder servo burned up. I replaced the servo and powered it back up. It immediately burned up an inner aileron servo. I'm at a loss. This is the 1st time i've incurred any electrical issues with an airplane build. I have the Mercury setup in Acro Mode and voltage setup at 7.4v. I am running dual aileron servos on individual channels. Is there something in the mercury programming setup that may be causing this issue? Not sure what to do at this point. I purchased this powerbox from Chief Aircraft just this year. I have a call in with them and currently waiting for their return instructions. Any idea what may be happening? Appreciate your help!!