i have a digitech distortion pedal..plugged into my amp and guitar it works fine for the first 5 mins then the sound stops and i get like a cutting sound going on/off very rapidly...!?!?! weird i know

now i tried re-reading both manuals for amp and pedal in case theres some mono / stereo stuff in the way although the manuals werent any help..

i have a marshal avt 100... and im not using the ac adapter for the pedal cus i need to buy one...could that be the problem ? inbalance of voltage...