The Energy Cannon were a weapon in the animated series The New Adventures of He-Man.
The Energy Cannon was a weapon that the Evil Mutants found on the junk filled Carrus Sector Asteroid, apparently left behind there by a higly advanced alien race. Quakke failed to get the Cannon to fire, activating an ejector seat instead while the control panel short circuited.
Skeletor came up with a plan to kidnap the Scientists of Primus and force them to get all the old technology operational. Krex and Meldoc worked on the Energy Cannon, but instead of getting it to work, they sabotaged it so that when Skeletor tried to fire the cannon at He-Man and the scientists, the entire machine exploded instead.
After escaping in the Starship Eternia, Krex identified the weaponry as being 'Sagillian' devices.