You may already know but their are 3 different power supply's used in Dragon's Lair. Either will work.
National Power Supply
Data Power Supply
Condor Power Supply
The one that looks like a tank is in my game. No mater which one you get, take the board off and re solder any cold solder joints on the board. Mine had cold solder joints and it caused the power supply to catch on fire, real flames. It was a good thing I was looking at it when it went up in smoke. It was however repairable and still working. Mark Spaeth(Hudson Arcade) also at one time made a switcher power supply for Dragon's Lair but I don't think they are listed on his site so he might not have any but someone might have one.