Excuse this off topic post but I don’t know where else to ask and the technical knowledge on this forum may be able to help. I have a 12V. wall wart (NEC AD-400) that has not been used for several months due to damaged insulation. I decided to fix the damage and step one was to check that it still worked so I wouldn’t waste my time. Before I plugged it in I connected my meter to the output and got 15V. After sever days it still reads 15V. and has not yet been plugged into the AC. How can this be?
