So, my fender 100 dsp has been cutting in and out.  It does this constantly if i try to play even slightly loud.  if i hit it, the sound will come back on.  WHen the sound cuts out i can still hear a hum but absolutely nothing from the guitar.  Ive tried multiple guitars  so i know that is not the problem.  i even detached the circuit board and control panel from the casing and when i hit that i get the same result so i know its not the speaker.  HELP!