@marcan This reminds me of one of my French lessons where our teacher used to play back tapes with French dialogues he recorded off the TV at home.
Once during a break we wrapped one connector of the power plug with transparent tape.
Problem fixed.
@cgudrian @marcan Ah, techie tricks on teachers. This one took two weeks. We had an old-fashioned class room with glass in the door and brass door knobs. Week 1 smeared the doorknob with transparent glue (Bostik) and enjoyed teacher's expression through the glass. Week 2 teacher arrives, grins through the glass at us and carefully touches the doorknob with a finger tip. By the time he picked himself off the floor the HUGE and thoroughly charged capacitor had disappeared.